A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Discuss the Traveller RPG and its many settings
Moppy
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Moppy » Tue Feb 05, 2019 3:09 am

4,000 tons weight does not seem so far-fetched.

https://en.wikipedia.org/wiki/Beriev_Be-2500
The 'Beriev Be-2500 Neptun' (Бериев Бе-2500 Нептун) is a super heavy amphibious transport aircraft currently in design and development in the industries Beriev in Russia. The maximum takeoff weight is estimated at 2500 tons, hence its name.
https://en.wikipedia.org/wiki/Boeing_Pelican
The Boeing Pelican ULTRA (Ultra Large TRansport Aircraft) was a proposed ground effect fixed-wing aircraft under study by Boeing Phantom Works. Max. takeoff weight: 6,000,000 lb[22][12] (3,000 short tons; 2,700,000 kg; 2,700 t)
Abandoned, or under development, but real aerospace engineers considered it feasible enough to actually write it up and start work. Both designs are/were ground effect, with a supposed ability to climb to at least a few thousand meters of altitude.

I really don't have a problem with a 4,000 ton aircraft in a sci-fi setting. If it causes you a problem, remember that a brick can generate aerodynamic lift if the front is tilted up and you move it fast enough. All it has to do is deflect enough air downwards for the reaction to push it up (ignoring the the pressure differential, which is the other component of aerodynamic lift). As I've said before, the real problem is likely to be stability and control.

If "lift from reaction" ios counter-intuitive to what you have been taught in schools (they usually teach it badly), then while driving put your hand out of the window in a paddle and tilt it up. Note that your arm will be raised by the wind.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby phavoc » Tue Feb 05, 2019 4:00 am

I had a longer response to you, but it was full of snark and expressed my frustration with your responses. I have posted numerous links regarding aerospace engineering rules, how lift is determined, why wing and craft shape matter when it comes to generating lift, how the X-series of crafts only flew after being dropped from a B-52, and even links to the original engineering drawings and explanations by Martin aircraft (the people who designed the first series of lifting bodies). These guys were literally rocket scientists and aeronautical engineers. I, on the other hand ended my aeronautical engineering career after struggling with the higher levels of math. It turns out you should have mad math skillz to be an aerospace engineer.

You asked why these craft can't fly. It's very simple. I cannot make you understand these principles, or why drag matters. However I have located an educational slide series that will explain this in pretty basic detail. You can find the link here - https://www.slideshare.net/LindaJaquili ... mics-slide

You can choose to look at it, or not. You can choose to educate yourself on these basic concepts, or not. It's not hard to understand why the shape of the craft and their mass preclude them doing anything but gaining a little lift while descending from orbit at high velocities. It's not hard to understand why their wing surface is insufficient to generate appreciable lift at slow speeds.

One thing, that is indeed very hard, is to find a real-world example of an aircraft that masses 6,000 tons and can fly. They don't exist in reality. I'm not sure it's even practical, but if it were the wings would be massively large. Using the MGT core book, as I did, I cited the approximate width of the Type-R wing surface. I also provided other measurements (by the way, in Traveller a deck is considered 3m tall. So the double height cargo hold is 6m tall internally and total craft height would be 9m(ish)). With huge amounts of power and enough wing space you could indeed make a very heavy craft fly with wings. The Type-R being debated has neither of those. We don't even have a good idea of the thrust capability other than some back of the envelope guesswork.

So I challenge you to prove why it can. Learn how wings and thrust and lift and drag all go together. Come up with the most advantageous AOA that you can for that wing. Hell, even estimate it to be like a true aircraft wing and now how it is in the illustrations. Give yourself the best lift coefficient that you can. But keep the mass at 4,000 tons and wing space no wider than 27m. Show me it can generate enough lift to do something. You've already guessed at the thrust, so you know the maximum. Even assume zero drag. Run the equation and show that it's possible.

The basic maxims of flight - if your Thrust > Drag and Lift > Weight you will fly. Otherwise you don't get off the ground from lift generated by your wings. The Type-R, based upon any of the illustrations, has a huge ton of drag and a very non-aerodynamic wing design with the massive flattened wing roots.

I am comfortable that science and flight theory are on my side. A simple cursory review will show that to be a true statement. I do not believe you can say the same for your argument.

You can accept it or not (though clearly I believe you are in the latter category). As far as I can tell you simply want it not to be and you are working mightily as justifying why it can't.

Just FYI, I will no longer be trying to quote you, or responding to your quotes in the way you do. That is no different than people quoting scripture for their own purposes when the passage, taken as a whole says something entirely different. It is a disingenious way to debate in a text format and is not illustrative of the points being debated. Based on your responses here and elsewhere I know that you probably won't stop for that very reason.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby phavoc » Tue Feb 05, 2019 4:16 am

Moppy wrote:
Tue Feb 05, 2019 3:09 am
4,000 tons weight does not seem so far-fetched.

https://en.wikipedia.org/wiki/Beriev_Be-2500
The 'Beriev Be-2500 Neptun' (Бериев Бе-2500 Нептун) is a super heavy amphibious transport aircraft currently in design and development in the industries Beriev in Russia. The maximum takeoff weight is estimated at 2500 tons, hence its name.
https://en.wikipedia.org/wiki/Boeing_Pelican
The Boeing Pelican ULTRA (Ultra Large TRansport Aircraft) was a proposed ground effect fixed-wing aircraft under study by Boeing Phantom Works. Max. takeoff weight: 6,000,000 lb[22][12] (3,000 short tons; 2,700,000 kg; 2,700 t)
Abandoned, or under development, but real aerospace engineers considered it feasible enough to actually write it up and start work. Both designs are/were ground effect, with a supposed ability to climb to at least a few thousand meters of altitude.

I really don't have a problem with a 4,000 ton aircraft in a sci-fi setting. If it causes you a problem, remember that a brick can generate aerodynamic lift if the front is tilted up and you move it fast enough. All it has to do is deflect enough air downwards for the reaction to push it up (ignoring the the pressure differential, which is the other component of aerodynamic lift). As I've said before, the real problem is likely to be stability and control.

If "lift from reaction" ios counter-intuitive to what you have been taught in schools (they usually teach it badly), then while driving put your hand out of the window in a paddle and tilt it up. Note that your arm will be raised by the wind.
The Pelican's wing would would be 152m from wingtip to wingtip, with a total wing surface area of 4,000 sq meters. Using the Wing-in-Ground effect the width of the wing is 259m (effective, not actual). Blended wing aircraft have been created by NASA at scale level and seem quite promising. Though I'm not sure how many people might like a 10-row seating width at the planes widest.

Indeed a brick can generate lift. At high enough velocity nearly any object can. However, like a brick, when it slows down it drops like a brick. As long as one never wants to take off or land there is no issue. The problem being that generally speaking most captains who want to land on a planet will want to slow down to a stop, get out and stretch their legs a bit, and then take off again.
Your brick would have a slight problem doing that.

As to your hand out the window, that's very true. Try this - accelerate to 50mph and put a balsa wood aircraft out the window. Assuming it doesn't disintegrate let go. It will fly! Now do the same with the brick. It will... drop, though it will maintain the forward momentum you gave it from the car until it hits the ground and friction brings it to a halt. Now, lets change the experiment. Try to run a 50 yard dash. Time yourself, but more importantly feel how much energy it took to do that. Now tie a small parachute to yourself and give it about six feet of rope. Make the area of the chute about 3 feet in diameter. Have someone hold the chute open when you start running so that it's fully deployed. Now tell me how much different that 50 yard dash was with that chute dragging you. That's drag (resistance).
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby AnotherDilbert » Tue Feb 05, 2019 10:28 am

Moppy wrote:
The 'Beriev Be-2500 Neptun' (Бериев Бе-2500 Нептун) is a super heavy amphibious transport aircraft currently in design and development in the industries Beriev in Russia. The maximum takeoff weight is estimated at 2500 tons, hence its name.
The Boeing Pelican ULTRA (Ultra Large TRansport Aircraft) was a proposed ground effect fixed-wing aircraft under study by Boeing Phantom Works. Max. takeoff weight: 6,000,000 lb[22][12] (3,000 short tons; 2,700,000 kg; 2,700 t)
Thank you, that is very interesting. I had no idea that such heavy aircraft were even considered.

So the aerospace industry considers multi-kton aircraft aerodynamically feasible.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Moppy » Tue Feb 05, 2019 12:41 pm

phavoc wrote:
Tue Feb 05, 2019 4:16 am
I agree that how you get up to speed or stop in the first place is problematic. It's my main sticking point and requires a long runway, possibly with a ramp. As I don't like runways in my sci-fi this is the reason why I assume anti-grav in all ships. But, I can believe it's possible.

The brick tumbling when released from the car is a problem of stability & control, not lift. I am very open to advances in that since we really don't fully understand it right now, and in my lifetime I've seen many revolutionary advances in boat and aircraft shape and real-time control systems. Plus we don't even fully understand laminar airflow or turbluence either: they're currently experimenting with bumpy shark-skin like coatings to reduce drag on aircraft, and turbulence is an unsolved "millenium problem" for which a $1m prize is offered for a solution to the equations it uses.

The fact that we still need scale models in wind tunnels to design a boat or aircraft says something about our understanding. We don't need scale models of a bridge to optimise it.

I feel parachute drag is another example of a control problem, and not a thrust problem. The manevuer drive doesn't account for a ship's mass or even the presence of atmosphere (at least not in Mongoose) and seems to act as if it acted on a volume of space in vacuum. Therefore the parachute only serves to destabilise the craft (although there is maybe some limit to this, but I feel that most of their streamlined ships like the Type-R aren't too bumpy or stubby, and if they are, they have fuel scoop vents that can pass air through them).

Edited a bit for writing style and clarity.
Last edited by Moppy on Tue Feb 05, 2019 4:12 pm, edited 2 times in total.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby AnotherDilbert » Tue Feb 05, 2019 1:03 pm

phavoc wrote:
Tue Feb 05, 2019 4:00 am
I had a longer response to you, but it was full of snark and expressed my frustration with your responses.
Very will, I can try to respond to your wall of text with a wall of text on my own.

Thank you for not posting the snark. Snark rarely help convey meaning or facilitate communication.


I quote small snippets because that is how logic and maths, hence science, works. In order to draw conclusions each premiss must stand on its own merit. If any of the premisses are incorrect, then the conclusion is invalid.

Your conclusion that Traveller ships in general can't fly because (you believe) the Subbie can't fly, is an invalid conclusion, even if the premiss were true. You cannot show the general case to be true by providing an example, it is a fallacy known as faulty generalisation. en.wikipedia.org/wiki/Fallacies#Faulty_generalization


I looked at the slideshow. It, as expected, contains nothing that even hints that very large aircraft can't fly. I did contain the same lift formula that we have both quoted a few times:
Image
Basically, a heavier aircraft needs bigger wings and/or higher take off speed, to be able to take off. Or as the slide show puts it:
Image
Note that the lift coefficient (Cl) is not determined by glancing at a picture of the aircraft, but is complex enough to have to be measured, hence it can't be accurately calculated.
In the specific, no-one, not I, not you, and not the author of these slides can accurately determine the lift coefficient or flight characteristics from a picture of the Subbie.

I we can't quantify lift, we can't determine if the Subbie can fly. As you noted, aerodynamics require a lot of maths.


But drag you say. Yes, aircraft have drag that limits their speed, hence lift. Well, we have the exact same problem, we can't accurately determine drag. You are probably correct that the Subbie has a lot of drag, but it also has a lot of thrust. If we cannot quantify drag and thrust, we can't quantify practical take off speed or top speed, hence lift.


You say you are confident that science proves you right, and that a cursory examination will show this, yet you can't provide any specific details to support your position. The very cursory examination I have done fails to verify your claim.

Show us some supporting facts, and I might believe you. Show us, e.g. a wing design for a 4000 tonne Subbie that can take off and fly to space, complete with specifications and calculations, however superficial (back-of-the-envelope calculations are probably enough?).

I'm sure it's very frustrating that strangers like me will not just accept your statements, but that is not how science (or life) works. If you claim something, you have to motivate it.


You challenge me to disprove your statement. That is a fallacy known as appeal to ignorance. en.wikipedia.org/wiki/Argument_from_ignorance
You claimed Traveller ships can't possibly fly, you prove it.

I have never claimed to be able to prove that any specific aircraft can or can't fly. I'm perfectly happy to play a game without learning all the intricate details of aerodynamics, or e.g. the chemistry and biology needed to make the life-support systems work.

I can provide an example of an aircraft with an compound delta wing with a fairly thick wing root, superficially similar to the Subbies wing:
Image
Image
It flies.

Edit: For clarity; I'm not suggesting that it proves anything about the Subbie, of course.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Moppy » Tue Feb 05, 2019 4:40 pm

Image

Handley-page victor above had some REALLY fat wings. B-1B might qualify too.

The Vulcan bomber might be even fatter, but it had full body length delta wings. B-2 would qualify too if you don't need a distinct body.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Moppy » Tue Feb 05, 2019 4:55 pm

I will add the vulcan to the "fat wing club"

Image
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby phavoc » Tue Feb 05, 2019 5:22 pm

Moppy wrote:
Tue Feb 05, 2019 12:41 pm
I agree that how you get up to speed or stop in the first place is problematic. It's my main sticking point and requires a long runway, possibly with a ramp. As I don't like runways in my sci-fi this is the reason why I assume anti-grav in all ships. But, I can believe it's possible.

The brick tumbling when released from the car is a problem of stability & control, not lift. I am very open to advances in that since we really don't fully understand it right now, and in my lifetime I've seen many revolutionary advances in boat and aircraft shape and real-time control systems. Plus we don't even fully understand laminar airflow or turbluence either: they're currently experimenting with bumpy shark-skin like coatings to reduce drag on aircraft, and turbulence is an unsolved "millenium problem" for which a $1m prize is offered for a solution to the equations it uses.

The fact that we still need scale models in wind tunnels to design a boat or aircraft says something about our understanding. We don't need scale models of a bridge to optimise it.

I feel parachute drag is another example of a control problem, and not a thrust problem. The manevuer drive doesn't account for a ship's mass or even the presence of atmosphere (at least not in Mongoose) and seems to act as if it acted on a volume of space in vacuum. Therefore the parachute only serves to destabilise the craft (although there is maybe some limit to this, but I feel that most of their streamlined ships like the Type-R aren't too bumpy or stubby, and if they are, they have fuel scoop vents that can pass air through them).

Edited a bit for writing style and clarity.
The brick doesn't have to tumble. It can drop down, in an arc to reflect it's forward velocity, but the mass of the brick outweighs any lift if could generate at that speed. CAN it tumble? Sure. But it won't automatically tumble. If dropped with precision so no tumble is added it just falls down due to it's mass.

The parachute example is a very basic drag problem, not control. Why? Because the definition of drag says so. From NASA (https://www.grc.nasa.gov/www/k-12/airplane/drag1.html)

"Drag is the aerodynamic force that opposes an aircraft's motion through the air. Drag is generated by every part of the airplane (even the engines!). How is drag generated?

Drag is a mechanical force. It is generated by the interaction and contact of a solid body with a fluid (liquid or gas). It is not generated by a force field, in the sense of a gravitational field or an electromagnetic field, where one object can affect another object without being in physical contact. For drag to be generated, the solid body must be in contact with the fluid. If there is no fluid, there is no drag. Drag is generated by the difference in velocity between the solid object and the fluid. There must be motion between the object and the fluid. If there is no motion, there is no drag. It makes no difference whether the object moves through a static fluid or whether the fluid moves past a static solid object."


There is an illustration on the page that shows this as well. You can only be drag-free in a vacuum.

As far as still needing to model fluid dynamics, you are entirely right. It's hugely complex and, as you pointed out, still not fully understood. Even the math and formulas we've been using for nearly a hundred years are still being perfected. I don't recall the name of the equation, but it had been in use in aerodynamics for about 70 years and was accepted as the default norm, until better computers and understanding revealed that the math was wrong. Obviously not enough to cause planes to stop flying, but it was wrong. Much like physics or mathematics in general, as we learn more about the universe and get better tools we'll probably go back and update other bedrock theories and laws.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby phavoc » Tue Feb 05, 2019 5:25 pm

Moppy wrote:
Tue Feb 05, 2019 4:55 pm
I will add the vulcan to the "fat wing club"

Image
Aye. The UK designed some of their initial jet aircraft with the air intakes in the wings. You can add the De Haviland Comet to the list. There are some advantages to having engines in the wings:

Propulsion

The Comet was powered by two pairs of turbojet engines buried in the wings close to the fuselage. Chief designer Bishop chose the Comet's embedded-engine configuration because it avoided the drag of podded engines and allowed for a smaller fin and rudder, since the hazards of asymmetric thrust were reduced.[56] The engines were outfitted with baffles to reduce noise emissions, and extensive soundproofing was also implemented to improve passenger conditions.[57]
The Comet 4's enlarged Rolls-Royce Avon engine intakes

Placing the engines within the wings had the advantage of a reduction in the risk of foreign object damage, which could seriously damage jet engines. The low-mounted engines and good placement of service panels also made aircraft maintenance easier to perform.[58] However, the Comet's buried engine configuration increased its structural weight and complexity. Armour had to be placed around the engine cells to contain debris from any serious engine failures; also, placing the engines inside the wing required a more complicated wing structure.[59]

The Comet 1 featured 5,050 lbf (22.5 kN) de Havilland Ghost 50 Mk1 turbojet engines.[30][60] Two hydrogen peroxide-powered de Havilland Sprite booster rockets were originally intended to be installed to boost takeoff under hot and high altitude conditions from airports such as Khartoum and Nairobi.[32][61] These were tested on 30 flights, but the Ghosts alone were considered powerful enough and some airlines concluded that rocket motors were impractical.[14] Sprite fittings were retained on production aircraft.[62] Comet 1s subsequently received more powerful 5,700 lbf (25 kN) Ghost DGT3 series engines.[63]

From the Comet 2 onwards, the Ghost engines were replaced by the newer and more powerful 7,000 lbf (31 kN) Rolls-Royce Avon AJ.65 engines. To achieve optimum efficiency with the new powerplants, the air intakes were enlarged to increase mass air flow.[64] Upgraded Avon engines were introduced on the Comet 3,[64] and the Avon-powered Comet 4 was highly praised for its takeoff performance from high altitude locations such as Mexico City.[65]


Go look at Burnelli's designs. He designed lifting-body style aircraft rather than flying wings. Engineering wise they seemed to have lots of advantages over standard wing-based ones, but his designs were never widely adopted.

Notice the Type-R does NOT have air-breathing turbines that allow the air to flow through the wings. Also compare the the wing structure to the Type-R. Take a look at the F-15 (large engine inlets along the fuselage). There are more aircraft that are the same. For each of these examples the airflow is through the inlets. Type-R BLOCKS the air, thus creating more drag.

It's not a good comparison.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby phavoc » Tue Feb 05, 2019 6:50 pm

AnotherDilbert,

The aircraft that you have shown, like Moppy, are not similar to the Type-R at all. In all the examples provided the aircraft are funneling air through the inlets, to compressors, then increasing the density, adding fuel, igniting, and then generating thrust. And the wings are also designed to accommodate the airflow over the wings and other lifting surfaces. Everything on the aircraft is designed to minimize drag and to use the airflow to either generate lift or minimize drag. Baffles and other objects/designs are also utilized to use air pressure to deflect incoming air to reduce drag. Look at the air intakes on F-15, and see how they are actually away from the body somewhat. The air flows between the forward part of the air intake and the aircraft body, but the body then slopes to deflect the air up/down. The inlets themselves help channel the air inside the inlets to help with compression. If you look at all the images each of you have shared you will see something similar.

Conversely the Type-R has far more massive wing roots and the air isn't flowing through at all. Inside is the fuel skimming inlets, so in that case the design is fine (though air pressure from skimming would be an interesting problem for them solve). While in flight the vents are closed, and with the design the air does not flow like it does on an aircraft. Instead it's a blunt object, thus the amount of drag coming from the wings and off the body of the ship is huge. Combine that with the shape of the wing and you should see that the airflow both over and under the wing would be disrupted, thus greatly reducing the ability of the wing to generate lift. Disruption of the airflow negates lift, and the more thrust you push through, the greater the disruption. In spite of what "Tool Man" Tim Taylor says, more power is not the answer to all problems.

Thank you for looking at the slides. At no time have I stated a maximum size for an aircraft, nor have I argued that very large aircraft are impossible to build nor are they impossible to fly. I have continually stated the same thing - Traveller vessels have too much mass and too little lift to take off/land. "Flying" has many meanings. I can make the many-times mentioned brick "fly", but not in the same manner a A380/An-225 can. And the brick can "fly" and it can "land", but if you were to apply the same definitions to an aircraft you would expect (or hope) the flight characteristics are quite different.

As stated there (and elsewhere), CI is generally determined experimentally. Which is why aircraft modeling in wind tunnels prior assembly is so important. Once that data is known they can design the wing and other aspects. The slide show should have illustrated rather clearly the forces that affect flight. And by viewing it you should have come away with a basic understanding of how a craft generates lift and why drag is such a huge issue for an aircraft. And, as you pointed out, lift cannot be determined based upon merely looking at a craft. This is true and applicable to both of our arguments. You neglect, however, another aspect of the equation - mass. As multiple examples have pointed out, mass is a HUGE factor in determining lift. As we have both cited examples of large craft we've both cited examples of their mass. Your assertion of more thrust to offset the mass is diametrically opposed to the concept of lifting area that has been provided in the literature and illustrations. The more mass your vessel has the greater the required wing area that is necessary to generate lift.

You would like a basic illustration (again)? Here you go. Let's use the An-225. Let's round up it's mass (fully loaded) to 700 tons. It's wing area is 905 square meters and it's wing span is 88m. The Type-R is 4,000 tons. We'll round down to 5x the mass of the An-225. Let's be generous and say all other things are equal (like drag). Let's also be generous and say the available thrust reduces the lifting surface requirement to a multiple of just 2.5 of the An-225. That would mean you would need a wing area of 2,260 square meters and a potential wing span of 220m (which is getting into the range of the Pelican craft). A simple review of the deckplans provided will show that there is insufficient area on the Type-R to meet this. And this even when you add in the area between the wings as lifting surface area.

You want to assert that my views are a fallacy? This is interesting because you can't prove your statement nor can you disprove mine. If you had read what I had written you will see my point has been the same throughout - reality states the designs are unable to generate lift to fly (and by fly I mean take off and land using their own lift generation). If you had paid attention you will also see that I stated that in the absence of lift being generated aerodynamically some other mechanism would have to supply that. I have postulated CG/AG lifting to do this. You insist thrusters can be overloaded to provide the same. I have used the idea of Occam's razor to suggest that my example is the simpler more logical one. You have resisted that idea. We have both cited canon literature to show that CG is defined, and in the versions that actually mention it you will see multiple examples of this. I have specifically cited GURPS which also adds in text that provides you with calculations to determine if your vessel is able to fly on it's own lift, or if it needs additional lifting capabilities to move.

You have stated repeatedly that you prefer to keep the game simple. I would believe that my view is far simpler than yours. You want to say it adds cost and complexity. Cost is something you choose to interject into the design system, it need not be there unless you insist. As you have pointed out, the MGT system is rather vague. In this case it is to my arguments advantage and will fit without a problem. Your explanation (overloading of the drive just for the simple actions of taking off and landing) is far more complex and outside the normal realm of thinking than mine is. Add to that overloads require ENG checks and may damage the drive. In my mind this alone makes it both impractical and unrealistic. Earlier it was asked of each of us to show why our reasoning made more sense in the Pirates of Drinax treasure ship taking off from a 1.4G world with a 1G drive. My example had no logical gyrations nor did I have to cite multiple past versions to provide an explanation. Yours was, ah, rather less helpful and explanatory.

Whether you like it or not, Occam's razor is an accepted modeling tool. It's usefulness here is even more applicable because it is used more often in theoretical models than in real world ones where actual data can be used to prove or disprove a point. In this case I can only cite real world modeling and extrapolate. I would say that since Einstein, Planck, Heisenberg and other famous scientists used this to help develop their theories it's both acceptable and useful. You can, of course, choose to discard the concept and try something else. Though I would have to say there is a greater preponderence towards using my method than one you may choose.

TL;DR - Here is my proposal to be added to the rules that would settle this:
Traveller ships mass too much to generate sufficient aerodynamic lift for takeoff and landings. Therefore they must use a different method until they are able to generate sufficient velocity for their craft to generate lift on their own - assuming their hull shapes would allow for it. In order to take off and land, especially in constrained spaces, a secondary form of lift is required. Most ships will utilize some form of anti-gravity to provide them with lift, and then use their thrusters and main engine(s) for movement. This allows any craft, other than distributed, to enter an atmosphere and land at a starport (which requires the craft to have landing struts/wheels/pads installed). Ships of 10,000 Dtons or greater almost never will land on a surface, thus unless specifically designed for it are unable to do so. For spacecraft the cost of such lifting modules is considered to be included in the cost of their hull.

One paragraph that solves that neatly solves the issue. With some editing it could probably be cut down in length, or possibly more clarity added to it. Notice that by clarifying things no design or rule is broken nor are any other changes required.

I am interested in you providing an alternative solution that makes common sense and does not require any other rule set, requires no change to existing designs, and would allow for 1G ships to service worlds with greater than 1G. I believe my explanation above satisfies all of the above.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Moppy » Tue Feb 05, 2019 7:47 pm

Obviously the brick is powered. Since it's sufficiently powered and tilted up at the front, it generates lift by deflecting air downwards. It will also tumble to chaotic forces and then lose lift. Maintaining the precise angle to generate lift is problem of control. I have absolutely no idea why you think the air cannot generate enough force to provide sufificient lift, as wind storms like tornados can easily lift bricks.

Drag from parachutes don't matter. The maneuver drive ignores it. It generates the same acceleration in vacuum and in atmopshere, right? Therefore there is almst zero drag on a ship powered by that engine. Although as I said, there i obviously some limit. Parachutes will flap about and cause minute attitude shifts, hence it's a control problem to maintain your angle. The reduction of drag also means less lift, which is problematic. There's still the bernoulli effect :-)

I don't claim those planes are identical to a Type-R. Just that saying the wings of a Type-R are too fat is unsupportable. None of us knows if the Type-R shape is possible under Traveller physics. Another thing to consider for Traveller ships are waveriders and ground effect.

edit: Actually I am assuming there must be a field that covers the ship that makes the drive ignore mass and atmopshere when providing acceleration. Parachutes may work if they're outside of it.

edit: Anyway the point is, let's not get side tracked into deploying parachutes. We don't know the drag on the ship because none of us can do the calculation, it's going to be much better in the future for a number of reasons, and if you have enough engine power, almost everythign flies anyway.
phavoc wrote:
Tue Feb 05, 2019 5:22 pm
Moppy wrote:
Tue Feb 05, 2019 12:41 pm
I agree that how you get up to speed or stop in the first place is problematic. It's my main sticking point and requires a long runway, possibly with a ramp. As I don't like runways in my sci-fi this is the reason why I assume anti-grav in all ships. But, I can believe it's possible.

The brick tumbling when released from the car is a problem of stability & control, not lift. I am very open to advances in that since we really don't fully understand it right now, and in my lifetime I've seen many revolutionary advances in boat and aircraft shape and real-time control systems. Plus we don't even fully understand laminar airflow or turbluence either: they're currently experimenting with bumpy shark-skin like coatings to reduce drag on aircraft, and turbulence is an unsolved "millenium problem" for which a $1m prize is offered for a solution to the equations it uses.

The fact that we still need scale models in wind tunnels to design a boat or aircraft says something about our understanding. We don't need scale models of a bridge to optimise it.

I feel parachute drag is another example of a control problem, and not a thrust problem. The manevuer drive doesn't account for a ship's mass or even the presence of atmosphere (at least not in Mongoose) and seems to act as if it acted on a volume of space in vacuum. Therefore the parachute only serves to destabilise the craft (although there is maybe some limit to this, but I feel that most of their streamlined ships like the Type-R aren't too bumpy or stubby, and if they are, they have fuel scoop vents that can pass air through them).

Edited a bit for writing style and clarity.
The brick doesn't have to tumble. It can drop down, in an arc to reflect it's forward velocity, but the mass of the brick outweighs any lift if could generate at that speed. CAN it tumble? Sure. But it won't automatically tumble. If dropped with precision so no tumble is added it just falls down due to it's mass.

The parachute example is a very basic drag problem, not control. Why? Because the definition of drag says so. From NASA (https://www.grc.nasa.gov/www/k-12/airplane/drag1.html)

"Drag is the aerodynamic force that opposes an aircraft's motion through the air. Drag is generated by every part of the airplane (even the engines!). How is drag generated?

Drag is a mechanical force. It is generated by the interaction and contact of a solid body with a fluid (liquid or gas). It is not generated by a force field, in the sense of a gravitational field or an electromagnetic field, where one object can affect another object without being in physical contact. For drag to be generated, the solid body must be in contact with the fluid. If there is no fluid, there is no drag. Drag is generated by the difference in velocity between the solid object and the fluid. There must be motion between the object and the fluid. If there is no motion, there is no drag. It makes no difference whether the object moves through a static fluid or whether the fluid moves past a static solid object."


There is an illustration on the page that shows this as well. You can only be drag-free in a vacuum.

As far as still needing to model fluid dynamics, you are entirely right. It's hugely complex and, as you pointed out, still not fully understood. Even the math and formulas we've been using for nearly a hundred years are still being perfected. I don't recall the name of the equation, but it had been in use in aerodynamics for about 70 years and was accepted as the default norm, until better computers and understanding revealed that the math was wrong. Obviously not enough to cause planes to stop flying, but it was wrong. Much like physics or mathematics in general, as we learn more about the universe and get better tools we'll probably go back and update other bedrock theories and laws.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby phavoc » Tue Feb 05, 2019 8:54 pm

Moppy wrote:
Tue Feb 05, 2019 7:47 pm
Obviously the brick is powered. Since it's sufficiently powered and tilted up at the front, it generates lift by deflecting air downwards. It will also tumble to chaotic forces and then lose lift. Maintaining the precise angle to generate lift is problem of control. I have absolutely no idea why you think the air cannot generate enough force to provide sufificient lift, as wind storms like tornados can easily lift bricks.

Drag from parachutes don't matter. The maneuver drive ignores it. It generates the same acceleration in vacuum and in atmopshere, right? Therefore there is almst zero drag on a ship powered by that engine. Although as I said, there i obviously some limit. Parachutes will flap about and cause minute attitude shifts, hence it's a control problem to maintain your angle. The reduction of drag also means less lift, which is problematic. There's still the bernoulli effect :-)

I don't claim those planes are identical to a Type-R. Just that saying the wings of a Type-R are too fat is unsupportable. None of us knows if the Type-R shape is possible under Traveller physics. Another thing to consider for Traveller ships are waveriders and ground effect.
Umm, in my example the brick was being held by a hand in a car at 50mph. And it was an unpowered brick. Most bricks, I think, would fall within that category. As I mentioned previously (original data can be found here - https://www.researchgate.net/publicatio ... fting_Body) the lift-to-drag ratio of a brick is 0 with a glide angle of 90 degrees. The glide angle for a lifting body is 16 degrees, the space shuttle is 12 degrees. A tumbling brick wouldn't have one since it's tumbling (well, technically, it would have more than one, as it would run through a whole bunch as it tumbled, but effectively it would have none).

As has been continually cited, yes, the brick CAN generate lift - but ONLY when the forward velocity is sufficient to overcome both mass and drag. And it doesn't generate lift by deflecting air downwards, lift is generated by air pressure being different above and below couple with the speed of the air. If air is moving faster above than below then no lift can be generated. The space shuttle and the X-series lifting bodies also would adjust their angle of attack. Again, going back to the boys from NASA, click on the link here - https://www.nasa.gov/centers/johnson/pd ... 26-241.pdf - refer to page 12. You will see how the shuttle angles it's nose to take advantage of drag during the deorbiting. The X-series craft, also designed to be fly from orbit, do the same. The lift is there to offset their 'brick' status and to allow for the craft to travel farther, thus giving them more landing sites. The NASA article also gives a lot of information regarding pressure and other issues that spacecraft have to deal with deorbiting. Which is another reason why using anti-gravity is a wonderful thing - less stress, less heat, less everything when entering the atmosphere. You can essentially 'sink' to your landing spot, though air turbulence and such would probably require some powered flight in order to have more control and speed.

As to your tornado question, that's simple. Tornadoes create vortexes. They also create pressure differentials. Air pressure is something aircraft also deal with to generate lift. High pressure on the ground and lower pressure in the tornado, combined with the vortex, create lift. A tornado is very destructive thing with a helluva lot power in it. Things far heavier than a brick get picked up. I've never said air cannot generate enough force to provide lift. Please go back and re-read what I have said (and what I have quoted and cited). You will find that to be an incorrect statement.

Why do you think drag does not matter? Even if you don't want to listen to me it doesn't make your assumption wrong. Drag is a force just like lift. You can disbelieve me all day long but that won't change the science. It's not me, personally, saying that by the way.

M-drive does not ignore drag. NOTHING flying ignores drag unless there is a field surrounding the object that ignores fluid dynamics. An M-drive may be able to generate the same THRUST in both atmosphere and vacuum - however vaccum has zero drag and atmosphere has infinitely more. The greater the density the more drag there is and the more thrust you must apply to maintain your current flight envelope. Again you need not believe me personally. Do just a teeny-tiny amount of investigations and you will find this to be a true statement.

I agree that none of us know the true shape of the wing. But the illustrations provided, along with the obvious characteristics from the illustrations and how they differ so greatly from the ones you provided allow us to have an inference. While you may not want it to be true, you cannot deny how aerodynamics work. And even a cursory review of the field will support my point. I'm having a problem embedding images, but you can see from the drag curve diagram that as velocity increases so does drag - https://en.wikipedia.org/wiki/Lift-to-d ... flight.svg
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby AnotherDilbert » Wed Feb 06, 2019 1:08 pm

Directing monologue wall of text at each another obviously didn't enhance clarity. I will respond directly to what you actually wrote, in specific.

phavoc wrote: The aircraft that you have shown, like Moppy, are not similar to the Type-R at all.
AnotherDilbert wrote: For clarity; I'm not suggesting that it proves anything about the Subbie, of course.

phavoc wrote: In all the examples provided the aircraft are funneling air through the inlets, to compressors, then increasing the density, adding fuel, igniting, and then generating thrust. And the wings are also designed to accommodate the airflow over the wings and other lifting surfaces. Everything on the aircraft is designed to minimize drag and to use the airflow to either generate lift or minimize drag. Baffles and other objects/designs are also utilized to use air pressure to deflect incoming air to reduce drag. Look at the air intakes on F-15, and see how they are actually away from the body somewhat. The air flows between the forward part of the air intake and the aircraft body, but the body then slopes to deflect the air up/down. The inlets themselves help channel the air inside the inlets to help with compression. If you look at all the images each of you have shared you will see something similar.
It's good that you explain what you mean, rather than a flat statement that it can't fly, thank you.

Yes, you have stated quite a few times that you BELIEVE the Subbie is not very streamlined and does not generate very much lift, after having seen a few hand drawings of the craft. You are still completely unable to quantify how much lift and drag the airframe generates.

phavoc wrote: At no time have I stated a maximum size for an aircraft, nor have I argued that very large aircraft are impossible to build nor are they impossible to fly. I have continually stated the same thing - Traveller vessels have too much mass and too little lift to take off/land.
Then I have no idea what you mean. You appear to say that massive aircraft can potentially fly, but if Traveller is involved they can't. That is logically incoherent, so I assume you don't mean that and I'm misunderstanding you completely.

Do you mean that you believe the Subbie can't fly, and you know nothing about Traveller spacecraft in general?

Can we agree that if we design a Traveller spacecraft and draw large enough wings on it, then it could fly?

phavoc wrote: As stated there (and elsewhere), CI is generally determined experimentally. Which is why aircraft modeling in wind tunnels prior assembly is so important. Once that data is known they can design the wing and other aspects.
The lift coefficient is for the entire airframe, including the wing. The wing is not designed after Cl is measured.

As far as I know the complete design is iteratively refined in computer simulation and windtunnels, then we can measure the final Cl in some specific cases of speed, angle of attack and air temperature, hence density.

phavoc wrote: The slide show should have illustrated rather clearly the forces that affect flight. And by viewing it you should have come away with a basic understanding of how a craft generates lift and why drag is such a huge issue for an aircraft.
Yes, a very basic understanding, just as I had before this discussion started.

phavoc wrote: And, as you pointed out, lift cannot be determined based upon merely looking at a craft. This is true and applicable to both of our arguments.
Agreed.

So you agree that we don't know the actual lift of the Subbie, hence whether it can fly or not?

phavoc wrote: You neglect, however, another aspect of the equation - mass. As multiple examples have pointed out, mass is a HUGE factor in determining lift.
No, lift is an aerodynamic force, unrelated to the mass of the aircraft.

You have continuously complained when I have introduced mass and hence Newtonian mechanics into the discussion. I have no idea why you believe I want to disregard mass.

phavoc wrote: As we have both cited examples of large craft we've both cited examples of their mass. Your assertion of more thrust to offset the mass is diametrically opposed to the concept of lifting area that has been provided in the literature and illustrations. The more mass your vessel has the greater the required wing area that is necessary to generate lift.
Lift is proportional to wing area AND air flow speed squared, as we seems to have agreed before.
Thrust gives speed, as Newton explained; Speed gives lift, as aerodynamics explains.
Hence heavier aircraft need larger wings and/or higher take off speed to take off. Wing area alone is not sufficient to calculate lift.

phavoc wrote: You would like a basic illustration (again)? Here you go. Let's use the An-225. Let's round up it's mass (fully loaded) to 700 tons. It's wing area is 905 square meters and it's wing span is 88m. The Type-R is 4,000 tons. We'll round down to 5x the mass of the An-225. Let's be generous and say all other things are equal (like drag). Let's also be generous and say the available thrust reduces the lifting surface requirement to a multiple of just 2.5 of the An-225. That would mean you would need a wing area of 2,260 square meters and a potential wing span of 220m (which is getting into the range of the Pelican craft). A simple review of the deckplans provided will show that there is insufficient area on the Type-R to meet this. And this even when you add in the area between the wings as lifting surface area.
Yes, this is roughly the same back of the envelope calculation I made a few days ago.
AnotherDilbert wrote:
Mon Jan 28, 2019 7:20 am
This lets us estimate the needed wing area for a Subbie. ...
And I agree that it probably need a bigger wing than it appears to have in some illustrations. So I assume it has, since the illustrations are inexact.

The wing shape of the subsonic An-225 is completely inappropriate for the hypersonic Subbie, as I assume you know, so the wing span you calculated is irrelevant to the Subbie.

phavoc wrote: You want to assert that my views are a fallacy? This is interesting because you can't prove your statement nor can you disprove mine.
Your view can of course not be a fallacy, your specific attempts at conclusions can be.
Which specific statements would that be?

phavoc wrote: If you had read what I had written you will see my point has been the same throughout - reality states the designs are unable to generate lift to fly (and by fly I mean take off and land using their own lift generation).
Yes, you believe that some unspecified designs and the Subbie are unable to generate enough lift and are unable to prove it?

phavoc wrote: If you had paid attention you will also see that I stated that in the absence of lift being generated aerodynamically some other mechanism would have to supply that. I have postulated CG/AG lifting to do this.
Yes, that is abundantly clear.

phavoc wrote: You insist thrusters can be overloaded to provide the same.
No, I have demonstrated that Traveller canon says that M-drive thrust can be vectored. In MT that requires overloading, in Gurps and T5 it apparently does not. MgT says nothing about this.

phavoc wrote: I have used the idea of Occam's razor to suggest that my example is the simpler more logical one. You have resisted that idea.
You want to introduce extra assumptions about how ships move, and extra magical technology to make them do so. Occam would suggest these assumptions are unnecessary.

phavoc wrote: We have both cited canon literature to show that CG is defined, and in the versions that actually mention it you will see multiple examples of this. I have specifically cited GURPS which also adds in text that provides you with calculations to determine if your vessel is able to fly on it's own lift, or if it needs additional lifting capabilities to move.
Agreed, but we seem to completely disagree about how contragrav works in Traveller.

phavoc wrote: You have stated repeatedly that you prefer to keep the game simple. I would believe that my view is far simpler than yours.
And I believe that it is far simpler to keep Traveller canon and not introduce extra drive systems.

phavoc wrote: You want to say it adds cost and complexity. Cost is something you choose to interject into the design system, it need not be there unless you insist. As you have pointed out, the MGT system is rather vague. In this case it is to my arguments advantage and will fit without a problem.
AG/CG systems are specified in many Traveller design systems, including the MgT2 Vehicle system. They require volume, mass, power, and cost. I see no reason it would suddenly become free, either in cost or volume.

We disagreed about this a week ago, just restating your belief does not make it more convincing.

phavoc wrote: Your explanation (overloading of the drive just for the simple actions of taking off and landing) is far more complex and outside the normal realm of thinking than mine is.
Vectored thrust is not my explanation, it's Traveller canon.

It's so 'outside the normal realm of thinking' that is has been used for decades:
Image

phavoc wrote: Add to that overloads require ENG checks and may damage the drive. In my mind this alone makes it both impractical and unrealistic.
You have added that to the discussion, not I. In MT the drives required overload but required no rolls to hover. In Gurps the drives required no rolls.
MgTs says:
Landing at a starport requires a Routine (6+) Pilot check (1D x 10 seconds), but most pilots will take 1D minutes to perform a landing, and gain DM+2 on the task.

Misrepresenting what I have actually said does not strengthen your arguments, but rather the opposite, in my opinion.

phavoc wrote: Earlier it was asked of each of us to show why our reasoning made more sense in the Pirates of Drinax treasure ship taking off from a 1.4G world with a 1G drive. My example had no logical gyrations nor did I have to cite multiple past versions to provide an explanation. Yours was, ah, rather less helpful and explanatory.
I haven't read the source, neither do I have full specifications for the ship. I have no idea what happened in that particular case. My "less helpful" suggestion was quoting you.

phavoc wrote: Whether you like it or not, Occam's razor is an accepted modeling tool. It's usefulness here is even more applicable because it is used more often in theoretical models than in real world ones where actual data can be used to prove or disprove a point. In this case I can only cite real world modeling and extrapolate. I would say that since Einstein, Planck, Heisenberg and other famous scientists used this to help develop their theories it's both acceptable and useful. You can, of course, choose to discard the concept and try something else. Though I would have to say there is a greater preponderence towards using my method than one you may choose.
I have never questioned Occam. I question your assertion that adding extra assumptions and drive systems to change Traveller canon is the simpler explanation.

phavoc wrote: TL;DR - Here is my proposal to be added to the rules that would settle this:
Traveller ships mass too much to generate sufficient aerodynamic lift for takeoff and landings. Therefore they must use a different method until they are able to generate sufficient velocity for their craft to generate lift on their own - assuming their hull shapes would allow for it. In order to take off and land, especially in constrained spaces, a secondary form of lift is required. Most ships will utilize some form of anti-gravity to provide them with lift, and then use their thrusters and main engine(s) for movement. This allows any craft, other than distributed, to enter an atmosphere and land at a starport (which requires the craft to have landing struts/wheels/pads installed). Ships of 10,000 Dtons or greater almost never will land on a surface, thus unless specifically designed for it are unable to do so. For spacecraft the cost of such lifting modules is considered to be included in the cost of their hull.
Yes, I realise you want to change Traveller to fit your view of how ships should land. I see no need.

phavoc wrote: I am interested in you providing an alternative solution that makes common sense and does not require any other rule set, requires no change to existing designs, and would allow for 1G ships to service worlds with greater than 1G. I believe my explanation above satisfies all of the above.
And I completely disagree with your definition of common sense.

I think aircraft using wings are more common sense than magical CG drives that can ignore some consequences of gravity but not others, while having no cost or volume.

If you wish I can restate what I said in my first post in this thread:
AnotherDilbert wrote:
Sun Jan 27, 2019 8:51 am
So, how does ships take-off from hi-grav planets? Either they have wings and can fly like airplanes (cf. Subsidised Merchant) or they simply don't land (and use a highport instead).

This makes a M-2 drive very useful.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Annatar Giftbringer » Wed Feb 06, 2019 1:26 pm

n MT that requires overloading, in Gurps and T5 it apparently does not. MgT says nothing about this.
How do Gurps and T5 handle thrust vectoring?
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby AnotherDilbert » Wed Feb 06, 2019 1:39 pm

Moppy wrote:
Tue Feb 05, 2019 7:47 pm
Drag from parachutes don't matter. The maneuver drive ignores it. It generates the same acceleration in vacuum and in atmopshere, right? Therefore there is almst zero drag on a ship powered by that engine.
No, M-drives do not imply that we ignore drag, phavoc is correct. M-drives just provide thrust.

LBB2 states that Atmospheric Braking (aka drag) slows spacecraft down.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby AnotherDilbert » Wed Feb 06, 2019 1:44 pm

Annatar Giftbringer wrote: How do Gurps and T5 handle thrust vectoring?
They just state that you can vector thrust, e.g.:
Starships, p37 wrote:A maneuver drive (M-Drive) is a reactionless thruster that produces thrust without fuel or reaction mass. Each module has a vectored reactionless thruster and a power-plant slice to run it.
Starships, p40 wrote:For extra detail, a ship required to ny in an atmosphere must have enough lift to compensate for its weight. This lift can come from three different locations: the hull (via streamlining). contragravity, or vectored drives.
Starships, p40 wrote:If the CG or vectored drives can't keep it in the air and ...
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Annatar Giftbringer » Wed Feb 06, 2019 1:57 pm

Thanks!
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Condottiere » Wed Feb 06, 2019 2:00 pm

Image

Flying wing.

Image
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby phavoc » Wed Feb 06, 2019 4:20 pm

I see you are back at trying to snippet an argument to death, and, as usual, ignoring all those inconvenient things that interfere with your argument. Very well, let's blow this puppy up.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
It's good that you explain what you mean, rather than a flat statement that it can't fly, thank you.

Yes, you have stated quite a few times that you BELIEVE the Subbie is not very streamlined and does not generate very much lift, after having seen a few hand drawings of the craft. You are still completely unable to quantify how much lift and drag the airframe generates.
You have yet to provide a counter to all of the information available for the Type-R. It's mythical (unlike the things I'm providing). Unless and until you can provide engineering drawings and data from it's testing all anyone has to go by are the illustrations and the text description. Since you cannot provide any of the requested your, and mine, only source of information is the aforementioned illustrations. If you don't like the ones I've provided or referenced, please provide the baseline illustration you feel best represents the Type-R.

I have posted numerous times real, logical, and proven examples of the laws of aerodynamics, how lift is generated from craft traveling through the air. You have provided nothing of note in return. The preponderence of science and evidence firmly lies on my side. I still await a logical & reasonable rebuttal to how it can fly. Since you continue to not provide such an argument I can only assume that you neither have one nor that you believe you can present a logical one to defend your viewpoint. I need not quantify anything since you have provided nothing to substantiate your argument that it can. Your argument is one that you hear on the playground not one that should be debated between adults. Step up and prove your point - in at least SOME way.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: At no time have I stated a maximum size for an aircraft, nor have I argued that very large aircraft are impossible to build nor are they impossible to fly. I have continually stated the same thing - Traveller vessels have too much mass and too little lift to take off/land.
Then I have no idea what you mean. You appear to say that massive aircraft can potentially fly, but if Traveller is involved they can't. That is logically incoherent, so I assume you don't mean that and I'm misunderstanding you completely.

Do you mean that you believe the Subbie can't fly, and you know nothing about Traveller spacecraft in general?

Can we agree that if we design a Traveller spacecraft and draw large enough wings on it, then it could fly?
I cannot be held responsible for your continued feigned ignorance when you encounter something you don't like. If you cannot comprehend the meaning behind those two sentences then I suggest you exit this debate for you are unable to respond in a cogent manner.
1) Traveller ships are heavy.
2) Aeronautical lift requires surface area.
3) Traveller ships have very little lifting surface area when compared to their mass.
4) The heavier something is, the more lifting surface it requires.
5) All objects have drag in a fluid environment.
6) The faster you go the more drag you create. Infinite thrust creates infinite drag.
7) Fluid environments include air and water.
8) To generate lift you have to go fast.
9) The laws of aerodynamics are applicable to Traveller ships.
10) At all times I have continually maintained the same stance - Traveller ships have to much mass and too little surface area to generate enough lift to takeoff or land using aerodynamics.
11) There is no theoretical upper limit on how big or how heavy a craft can be to fly like an airplane.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: As stated there (and elsewhere), CI is generally determined experimentally. Which is why aircraft modeling in wind tunnels prior assembly is so important. Once that data is known they can design the wing and other aspects.
The lift coefficient is for the entire airframe, including the wing. The wing is not designed after Cl is measured.

As far as I know the complete design is iteratively refined in computer simulation and windtunnels, then we can measure the final Cl in some specific cases of speed, angle of attack and air temperature, hence density.
Very good. That's a factual statement. The ENTIRE aero-structure is tested. So in this case we'd have to include the very non-aerodynamic nose of the Type-R, the increased drag resulting from the inset windows, the increased drag from the launch on top, the drag created from the rear. All of the craft will produce potential lift and drag. As you can see (if you will look), the amount of lift generated from an airliners body is insignificant when compared to what is generated with the lifting surfaces (wings and tail, assuming we are using commercial aircraft and not modern military ones).

This, however, has nothing to do with the Type-R being unable to generate enough lift aerodynamically to takeoff or land.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: The slide show should have illustrated rather clearly the forces that affect flight. And by viewing it you should have come away with a basic understanding of how a craft generates lift and why drag is such a huge issue for an aircraft.
Yes, a very basic understanding, just as I had before this discussion started.
I find that to be a curious statement. If, as you claim, you already had a very basic understanding, you have not shown it in your responses when concepts like lift and drag have been mentioned. Again, this response is not necessary to prove/disprove the ability of the Type-R to generate lift to takeoff/land with it's lifting surfaces.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: And, as you pointed out, lift cannot be determined based upon merely looking at a craft. This is true and applicable to both of our arguments.
Agreed.

So you agree that we don't know the actual lift of the Subbie, hence whether it can fly or not?
I agree that the exact amount of lift is not determinable without having all the necessary information to plug into the formula. However you fail to acknowledge any of the other aspects of this view. Neither of us will be able to produce data to generate a somewhat accurate estimate of the lift generated by the hull. That is an agreed upon issue. Nevertheless, the preponderance of evidence as provided illustrates why the Type-R is unable to do so. You have continually refused to acknowledge this and provided nothing to rebut it. Using actual physical laws and applying them to an object such as the Type-R (as provided by copious illustrations - including the original ship) show us that the design will generate massive amounts of drag. It was you who wanted to used 4,000 tons for the mass of the Type-R. Applying that mass to how wings work is easy. As you have proven elsewhere you are able to solve for missing information (your Newton equations). You should know that you can simply toss out the CI portion and use base numbers. And that basic equation will state that the wing area (even giving you perfect lift for the entire underbody with zero drag) is insufficent to generate enough lift to takeoff or land. It is your refusal to accept common sense and logic that is the barrier.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: You neglect, however, another aspect of the equation - mass. As multiple examples have pointed out, mass is a HUGE factor in determining lift.
No, lift is an aerodynamic force, unrelated to the mass of the aircraft.

You have continuously complained when I have introduced mass and hence Newtonian mechanics into the discussion. I have no idea why you believe I want to disregard mass.
Sigh.... And there you were saying you had a basic understanding. So either you lied upthread or you are lying here, or you lied upthread and you are professing true ignorance here. I have stated, repeatedly, that aerodynamic equations are MORE than simple newtonian ones. Since you apparently can't pay attention to a mass of text I have restated that here. I am sure you will ignore it again because, like Al Gore pointed out, it's an inconvenient truth. You said (now I doubt it) that you went through the slide show. It was rather long, but aerodynamics is complicated so it has to be. In that slide show mass is one of the items mentioned. The mass of the object flying determines how much lift is required to keep it flying. For someone who has such an attraction to Newton I fail to see how you cannot grasp such a simple concept. If Newton can grasp it, and you are able to parrot it back, how can you profess the view of a failure to understand the mass and lift are connected for aircraft?

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: As we have both cited examples of large craft we've both cited examples of their mass. Your assertion of more thrust to offset the mass is diametrically opposed to the concept of lifting area that has been provided in the literature and illustrations. The more mass your vessel has the greater the required wing area that is necessary to generate lift.
Lift is proportional to wing area AND air flow speed squared, as we seems to have agreed before.
Thrust gives speed, as Newton explained; Speed gives lift, as aerodynamics explains.
Hence heavier aircraft need larger wings and/or higher take off speed to take off. Wing area alone is not sufficient to calculate lift.
Yes. And all objects have drag. Drag is the direct counter to thrust. As aerodynamics explains you cannot bully your way through the laws of physics. Newton explains that, too. How can you profess an understanding of physics, especially newtonian ones, and not grasp the basics of aerodynamics? I am at a loss to try to balance these two opposing viewpoints.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: You would like a basic illustration (again)? Here you go. Let's use the An-225. Let's round up it's mass (fully loaded) to 700 tons. It's wing area is 905 square meters and it's wing span is 88m. The Type-R is 4,000 tons. We'll round down to 5x the mass of the An-225. Let's be generous and say all other things are equal (like drag). Let's also be generous and say the available thrust reduces the lifting surface requirement to a multiple of just 2.5 of the An-225. That would mean you would need a wing area of 2,260 square meters and a potential wing span of 220m (which is getting into the range of the Pelican craft). A simple review of the deckplans provided will show that there is insufficient area on the Type-R to meet this. And this even when you add in the area between the wings as lifting surface area.
Yes, this is roughly the same back of the envelope calculation I made a few days ago.
AnotherDilbert wrote:
Mon Jan 28, 2019 7:20 am
This lets us estimate the needed wing area for a Subbie. ...
And I agree that it probably need a bigger wing than it appears to have in some illustrations. So I assume it has, since the illustrations are inexact.

The wing shape of the subsonic An-225 is completely inappropriate for the hypersonic Subbie, as I assume you know, so the wing span you calculated is irrelevant to the Subbie.]
First off, show me how the Type-R can go hypersonic (which is 5x the speed of sound or approximately 3,800mph or 1,700 meters/second). Please oh please explain that to me in aerodynamic terms. And, as you like to say, provide proof. I'd settle just to see the gyrations you will go through to explain how you can push an object through an atmosphere at that speed with just the nose of the Type-R. Please show me a hypersonic vehicle that has any similar designs (excluding objects that fall from space. All manned craft that humanity has put in orbit have fallen from the sky at hypersonic speeds. Type-R has to go UP, too).

Secondly, in order to get hypersonic (starting from the ground) you must first get to subsonic. As an aircraft it needs enough speed to generate the lift that is possible from a lifting surface.

Thirdly, I see you are studiously avoiding acknowledging the fact that the Type-R has insufficient lifting surface to generate lift according to science. You want to confuse your failure to prove your point by trying to make it to be a "illustrations are inexact". And you failed to acknowledge that the deckplans (which are relatively exact) clearly provide an estimated size for the wing. Even spotting you the 20% that the deckplans get to play with, your argument shows your point is a false one. The original illustration and deckplans from CT have not appreciably changed. So either the original creator and illustrator are wrong and you are right, or you are wrong and they are right.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: If you had read what I had written you will see my point has been the same throughout - reality states the designs are unable to generate lift to fly (and by fly I mean take off and land using their own lift generation).
Yes, you believe that some unspecified designs and the Subbie are unable to generate enough lift and are unable to prove it?
Nope. If by 'unspecified' designs you mean all of the actual real-world designs I have cited, you are incorrect (again). I have illustrated that using aeronautical laws (which do not change regardless of the time frame) the Type-R is too heavy to generate enough lift utilzing it's wings to fly like an aircraft. You have yet to disprove any of that. Your argument has continually hinged upon, well, nothing. I have time and time again cited how aeronautics works and how the Type-R (using all available provided data) cannot follow the laws of physics to match the book description. You simply don't like that.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: You insist thrusters can be overloaded to provide the same.
No, I have demonstrated that Traveller canon says that M-drive thrust can be vectored. In MT that requires overloading, in Gurps and T5 it apparently does not. MgT says nothing about this.
And you have clearly selected bits and pieces of various canon articles while avoiding the other bits and pieces of canon that dispute your same position. You have demonstrated continuosly that you are willing to selectively ignore anything that disagrees with your viewpoint. And you have demonstrated that you are willing to snippet things out of context, from canon literature no less, in an attempt to prove your point. But you have been caught time and again misrepresenting yourself and canon.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: I have used the idea of Occam's razor to suggest that my example is the simpler more logical one. You have resisted that idea.
You want to introduce extra assumptions about how ships move, and extra magical technology to make them do so. Occam would suggest these assumptions are unnecessary.
It's not an extra assumption at all. As you have previously stated, MGT is very unclear and high-level, hence your desire to pull selected quotes from multiple previous iterations. By the very definition it's not an "extra" assumption. I am using Occam's razor correctly. If anti-grav is magical, then canon literature, in all variations, also references the magic. Vehicles use anti-grav, personal harnesses use anti-grave. Oh, wait! Now I get it! Those people who used anti-grave were flung off the faces of all the planets when they activated the devices! Ah! Now I understand your viewpoint! The magical technology has magically erased itself from existence!

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: We have both cited canon literature to show that CG is defined, and in the versions that actually mention it you will see multiple examples of this. I have specifically cited GURPS which also adds in text that provides you with calculations to determine if your vessel is able to fly on it's own lift, or if it needs additional lifting capabilities to move.
Agreed, but we seem to completely disagree about how contragrav works in Traveller.
I don't seem to have a problem, but you apparently do. Somehow you think that a vessel activating it's anti-grav or CG would be magically flung off the planet, or perhaps finding itself drifting away. Yet, again magically, a vehicle utilzing the same technology has none of these problems. And, also apparently magically, your viewpoint of how it works doesn't seem to be referenced, nor user warning plastered anywhere about the dangers of turning on an anti-gravity device. Somehow everyone else seems to be able to grasp the concept and fit it within the gaming universe. Your view seems to be unique to yourself.

I am comfortable in continuing to disagree with your views.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: You have stated repeatedly that you prefer to keep the game simple. I would believe that my view is far simpler than yours.
And I believe that it is far simpler to keep Traveller canon and not introduce extra drive systems.
Your selective memory and quoting is showing up again. You've already acknowledged multiple versions of canon Traveller that state AG/CG lifting is present. You have already acknowledged that MGT is very vague about many things, thus your need to quote across multiple editions. And, by the above, you have already agreed that these are not extra drive systems. To wit, you've already agreed they are present and canon. You simply don't want to admit your argument is not holding up.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: You want to say it adds cost and complexity. Cost is something you choose to interject into the design system, it need not be there unless you insist. As you have pointed out, the MGT system is rather vague. In this case it is to my arguments advantage and will fit without a problem.
AG/CG systems are specified in many Traveller design systems, including the MgT2 Vehicle system. They require volume, mass, power, and cost. I see no reason it would suddenly become free, either in cost or volume.

We disagreed about this a week ago, just restating your belief does not make it more convincing.
You have yet to show what is included in the base cost for the hull. As you said, in other system, where they are stated, the majority of ships have them (that plan to land on planets at least). And, as you stated, MGT doesn't mention them. The design systems that have them provide for them in the stated designs. Your reference to the vehicle design system is disingenious since we are not talking about starships. The vehicle design system also reference wheeled and tracked propulsion. It references many things that don't exists in the starship system, and vice versa.

Lifesupport takes volume, power, mass and cost. Though didn't you say that mass is of no consequence in MGT, it's all volume based? So mass is out of the discussion and it never should have been referenced (another non-sequitur). I believe MGT just lumps all ships systems into a Power bucket. If you want to split it out, how much is allocated to the inertial compensator? How much to the lighting? How much to... My way is far simpler - it's there and it's a system that is only needed for planetary activities. All ships have more than enough power for this even under the amorphous design system.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: Your explanation (overloading of the drive just for the simple actions of taking off and landing) is far more complex and outside the normal realm of thinking than mine is.
Vectored thrust is not my explanation, it's Traveller canon.
Ships having CG for lift is not my explanation. It's Traveller canon.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
It's so 'outside the normal realm of thinking' that is has been used for decades:
Amazingly your Harrier jump jet is pictured flies according the previously cited laws of aerodynamics. Unless this image, too, is not correctly representing the Harrier. Since you are questioning all the of the Type-R imagery I think it's probably safer to say that all images are suspect, ergo they shouldn't be used because they may be suspect.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: Add to that overloads require ENG checks and may damage the drive. In my mind this alone makes it both impractical and unrealistic.
You have added that to the discussion, not I. In MT the drives required overload but required no rolls to hover. In Gurps the drives required no rolls.
MgTs says:
Landing at a starport requires a Routine (6+) Pilot check (1D x 10 seconds), but most pilots will take 1D minutes to perform a landing, and gain DM+2 on the task.

Misrepresenting what I have actually said does not strengthen your arguments, but rather the opposite, in my opinion.
Where is that happening? Quoting the rules is somehow misrepresenting what you said? In your zeal to misrepresent the rules you fail to add in those rules that weaken your argument. If you do not want the rules used (correctly) against you then I suggest you stop quoting rules. And, by the way, you have added tons of non-sequitur issues to this. If you don't like it, stop doing it.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: Earlier it was asked of each of us to show why our reasoning made more sense in the Pirates of Drinax treasure ship taking off from a 1.4G world with a 1G drive. My example had no logical gyrations nor did I have to cite multiple past versions to provide an explanation. Yours was, ah, rather less helpful and explanatory.
I haven't read the source, neither do I have full specifications for the ship. I have no idea what happened in that particular case. My "less helpful" suggestion was quoting you.
What source is there to read? The question was rather clear. The source was the question. The ship has 1G drives, the planetary gravity is 1.4. What other specifications are there to be provided? Whether it was Pirates of Drinax or some random planet in the Traveller universe the question remains the same. And, once again, you failed to provide an answer. Instead you seek to deflect the issue and make vague reasons on why you cannot, using your interpretation of the rules, answer it. All of this is a classic sign your argument cannot be relied upon to provide a valid answer.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: Whether you like it or not, Occam's razor is an accepted modeling tool. It's usefulness here is even more applicable because it is used more often in theoretical models than in real world ones where actual data can be used to prove or disprove a point. In this case I can only cite real world modeling and extrapolate. I would say that since Einstein, Planck, Heisenberg and other famous scientists used this to help develop their theories it's both acceptable and useful. You can, of course, choose to discard the concept and try something else. Though I would have to say there is a greater preponderence towards using my method than one you may choose.
I have never questioned Occam. I question your assertion that adding extra assumptions and drive systems to change Traveller canon is the simpler explanation.
Wow. Talk about conceptual twisting. You can't even accept the definition of what Occam's razor is. Not only that but you try to deflect by using a logical fallacy. Traveller canon is not being changed at all. For one things CG lift IS canon. Your fallacy is attempting to equate all of Traveller canon into a single set, which is of itself a fallacy because each version is it's own canon. To the best of my knowledge, if you want to use the word 'canon' then only T5 and MGT are canon because accepted canon includes only those versions currently in print. Or, if you want a more expansive definition, canon would be restricted specifically to each version, thus canon cannot be across multiple versions. Pick one definition and stick with it.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: TL;DR - Here is my proposal to be added to the rules that would settle this:
Traveller ships mass too much to generate sufficient aerodynamic lift for takeoff and landings. Therefore they must use a different method until they are able to generate sufficient velocity for their craft to generate lift on their own - assuming their hull shapes would allow for it. In order to take off and land, especially in constrained spaces, a secondary form of lift is required. Most ships will utilize some form of anti-gravity to provide them with lift, and then use their thrusters and main engine(s) for movement. This allows any craft, other than distributed, to enter an atmosphere and land at a starport (which requires the craft to have landing struts/wheels/pads installed). Ships of 10,000 Dtons or greater almost never will land on a surface, thus unless specifically designed for it are unable to do so. For spacecraft the cost of such lifting modules is considered to be included in the cost of their hull.
Yes, I realise you want to change Traveller to fit your view of how ships should land. I see no need.[/quoote]

It changes nothing. Unless you are conflating change with clarification. That's entirely possible. As you have agreed to, it's not changing Traveller at all. Some versions specifically call it out, others (such as MGT) say nothing about it. Ergo it's not change using MGT, it's clarification.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
phavoc wrote: I am interested in you providing an alternative solution that makes common sense and does not require any other rule set, requires no change to existing designs, and would allow for 1G ships to service worlds with greater than 1G. I believe my explanation above satisfies all of the above.
And I completely disagree with your definition of common sense.
I expect no less from you. In fact I now expect it.

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
I think aircraft using wings are more common sense than magical CG drives that can ignore some consequences of gravity but not others, while having no cost or volume.
Again, a reference to magic. When did the space orks and angry fairies start sprinkling magic in your set of rules, let alone with your sophmoric attempts at "logic"? Here you talk about aircraft using wings as common sense... yet you refuse to accept aeronautical laws that govern how they work. It is only you who speaks of magical CG drives. I've never argued for AG/CG drives, that's purely you boyo! My statements have been exclusively centered around CG/AG to provide lift. You have hysterically argued about people being flung off the planet (which vaguely reminds me of how people spoke of flight before they understood it. Silly ignorant people!). You cannot seem to grasp the basic concept that CG lift in a starship would perform no differently than what a vehicle does, or a person in a AG harness. Unless those people are magically flung off the planet, too. As to cost/volume, cost is already there with no defined list of what you spending on in a "hull", and volume is already an amorphous blob that it has no bearing. If you are so concerned about volume, tell me how ships get landing gear when it's not defined? How much do they cost? What is their volume?? Oh, wait, it's not defined and of no consequence since it's assumed to be part the cost of the "hull". Funny how common sense works...

AnotherDilbert wrote:
Wed Feb 06, 2019 1:08 pm
If you wish I can restate what I said in my first post in this thread:

So, how does ships take-off from hi-grav planets? Either they have wings and can fly like airplanes (cf. Subsidised Merchant) or they simply don't land (and use a highport instead).

This makes a M-2 drive very useful.
Hrm... since the argument has centered around the Type-R with it's 1G drive, AND since Type-R DOES land (unless you are going to try and argue they don't land), I would say your statement remains false. You claim to have a basic understanding of aeronautics so you should be able to understand the Type-R has insufficient lifting area to fly like an airplane. Unless you want to also reject all of that and just spew crap out.

The Drinax treasure ship is in canon material. It has a 1G drive, and no wings. It takes off and lands on a 1.4G planet. Take your rule and make that work. Oh, wait, according to your rule it can't land, but canon says it does. According to your rule it uses a highport instead, but canon again says it lands.

Seems canon is right and you are wrong.

For this post I left the snark = on because I feel it's warranted. For someone who posts some really good articles and thoughts your ignorance act is wearing thin. You aren't as ignorant as you are feigning to be. Why you are choosing to act like that I haven't a clue, though I have a suspicion. Based upon what you have written here and elsewhere I know you grasp these basic concepts when you claim you don't. You can do better than this. As long as you want to play that game the snark will remain in full force. If you grow tired of it you can, of course, abandon the discussion.
Last edited by phavoc on Wed Feb 06, 2019 5:16 pm, edited 1 time in total.

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