Suggestion, Super-streamlined, and Lifting hulls.

Discuss the Traveller RPG and its many settings
wbnc
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Re: Suggestion, Super-streamlined, and Lifting hulls.

Postby wbnc » Fri Dec 18, 2015 11:13 pm

phavoc wrote:The issue is going to be weight. Lift is possible, but you can also mass more than the lift you get, thus you have none.

Starships have armor hull plating, thus they will mass much more than the shuttle at a mere 82 tons. Because they use antigravity they have no need to use lightweight materials.
lifting bodies/aircraft are surprisingly powerful at keeping an object in the air..getting it off the ground is the real pain. the real limit on how heavy an aircraft can be is the takeoff weight... once it's got a running start say, dropping form orbit the aerodynamic forces have incredible power.

I dont see starships using lift only for sustained flight, but it would be a huge boost to be able to use aerodynamic forces in addition to your grav systems..the rules dont allow for reduced fuel consumption by powering back..but it would be an option if you could use your drives only for forward propulsion and natures own rules for lift.

only in an emergency do I see a starship depending on aerodynamic lift alone...it would be a very steep glide slope as I've said...but a bit of control and lift is better than none.....I can assure the landing will be, as my uncle says, " rough as a five miles of bad road"..literally.
phavoc
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Re: Suggestion, Super-streamlined, and Lifting hulls.

Postby phavoc » Sat Dec 19, 2015 12:55 pm

It seems like a huge design and cost burden for something that should be relatively rare. With anti grav you would be better off installing a one time emergency system that kicks in right before impact that would halt the downward angle and let the ship "land" before burning out.

It should have at least the same likelihood of helping get a ship down safely as a lifting body without the additional design costs of modifying your hull. Plus it would not have to worry about atmosphere density - the lift we are talking about would require one st least as dense as ours, and it wouldn't work in thin ones because of density being gone to provide lift.

As far as battle damage taking out the system, the lifting body would have the same problem. Too many holes increases drag and eliminates it's ability to sustain itself in the air. Not to mention with the control surfaces it can't maneuver or may even get into a spin, also making it impossible to generate lift.
wbnc
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Re: Suggestion, Super-streamlined, and Lifting hulls.

Postby wbnc » Sat Dec 19, 2015 7:25 pm

phavoc wrote:It seems like a huge design and cost burden for something that should be relatively rare. With anti grav you would be better off installing a one time emergency system that kicks in right before impact that would halt the downward angle and let the ship "land" before burning out.

It should have at least the same likelihood of helping get a ship down safely as a lifting body without the additional design costs of modifying your hull. Plus it would not have to worry about atmosphere density - the lift we are talking about would require one st least as dense as ours, and it wouldn't work in thin ones because of density being gone to provide lift.

As far as battle damage taking out the system, the lifting body would have the same problem. Too many holes increases drag and eliminates it's ability to sustain itself in the air. Not to mention with the control surfaces it can't maneuver or may even get into a spin, also making it impossible to generate lift.

the cast and expense could be covered with the streamlined option, buy it twice..the volume not such a huge deal...not if you aren't using spindly little wrings that cant even be used as fuel tanks.

as for atmospheric density...aircraft routinely fly at altitudes where the air is so thin a human is unconscious in seconds.

I'm not saying it would be without drawback mind you. and definitely not for every ship..but lifting hulls might be an option that might be employed regularly enough to make it an option designers keep around on the shelf for when someone wants it...

after all they still build seaplanes,flying boats, and pontoon attachments....as far as being widely practivcal flying boats had that train left the station decades ago.
Tenacious-Techhunter
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Re: Suggestion, Super-streamlined, and Lifting hulls.

Postby Tenacious-Techhunter » Mon Dec 21, 2015 3:30 am

Puddlejumpers are very important in places like Alaska and Africa; they are still made for good reason.
wbnc
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Re: Suggestion, Super-streamlined, and Lifting hulls.

Postby wbnc » Mon Dec 21, 2015 3:39 am

Tenacious-Techhunter wrote:Puddlejumpers are very important in places like Alaska and Africa; they are still made for good reason.
a case of local conditions requiring a type of craft outside the normal type/design.The puddle jumper is not a major commercial aircraft..but where it is useful, there is not much around to replace it.

Precisely why I think some vessels might have aerodynamic bodies...not every ship needs, it..or would it be widely profitable to have the modification..but there might be niches where it comes in handy.
Tenacious-Techhunter
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Re: Suggestion, Super-streamlined, and Lifting hulls.

Postby Tenacious-Techhunter » Mon Dec 21, 2015 4:26 am

For Spacecraft, it's trading Top Speed for Agility, I think.
phavoc
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Re: Suggestion, Super-streamlined, and Lifting hulls.

Postby phavoc » Mon Dec 21, 2015 2:21 pm

wbnc wrote:a case of local conditions requiring a type of craft outside the normal type/design.The puddle jumper is not a major commercial aircraft..but where it is useful, there is not much around to replace it.

Precisely why I think some vessels might have aerodynamic bodies...not every ship needs, it..or would it be widely profitable to have the modification..but there might be niches where it comes in handy.
The same can be said for all the adventure-class ships. A Free Trader is not a major commercial transport, neither is a subsidized merchant. They are, essentially the semi-trucks of the galaxy. But they are optimized to handle the low-end of the cargo spectrum which their larger commercial brethren are not.

The same is said for the types of aircraft in question. Sure, a 737 can more efficiently carry a bunch of people to an island hideaway - so long as the island is large enough to accommodate a 8,000ft runway. Which is why you still have those types of aircraft.

Firefighting aircraft that can land on a lake (or land), take on water and then fly to the fire are infinitely more flexible than than those aircraft that cannot.

But you do have a very valid point that some craft might do this. For emergency use only doesn't seem like a strong enough reason. However for say something like stealth insertions, or perhaps for those pilots who like to perform stunts with their craft, it makes sense and would be totally applicable.
Meeko100
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Re: Suggestion, Super-streamlined, and Lifting hulls.

Postby Meeko100 » Mon Dec 21, 2015 5:46 pm

Given how many Free-Traders there are running around, and the advantage that streamlining/lift surfaces would give to a small ship like that, it seems likely that there would indeed be a ton of ships running around with streamlining, because they are small enough to be able to land on planets without accidentally cleaning out a couple skyscrapers on the way in to land.

There's a point in size where that streamlining is no longer giving any real benefit, considering the likely unwieldiness of the vessel in atom for most places such a ship would be. 1000 ton heavy merchants don't usually go to frontier worlds to trade supplies. And they're a bit big to land at the planetary starport (or at least, it would be a bit of a pain to do so).

It seems to me that most sub 600 ton ships would have streamlining, just because they could possibly go places that it could get used, a la Bush Pilots and the like. And larger ships that feel the need to enter atmo would just have to muscle through it, with lower speeds be able to be achieved.
wbnc
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Re: Suggestion, Super-streamlined, and Lifting hulls.

Postby wbnc » Mon Dec 21, 2015 5:51 pm

It would definitely be a niche adaptation, and not for everyone. It might even be a matter of personal taste.

random thought alert
You know if you coupled an aerodynamic body with heat shielding it could allow a ship to pretend to be a rock...make a high speed entry...use the entry velocity, to power a pull out and then cruise at low power to avoid being detected. by the time a radar site spotted, if it spotted, the fact that that meteor just pulled a high gee aerobrake,, it might be too late to launch interceptors, alert ground batteries...

one factor that isnt supported by the rules that would make the concept useful is tha a ship with a lifting body could educe it's fuel use for long endurance atmospheric operations..such as a survey, scout, or prospector vessel.

if a ship is cruising it can reduce power to it's gravitics, and use aerodynamic lift to cut down on it's operation costs/down time.

@Meeko100
yeah that's what I was thinking when I started this thread. It would be a real waste on big ships, they just can't make full use of the modification....but that light trader who has to drop, then make two or three or more hops in atmo. It's an option..especially since it would make life easier on the pilot.
phavoc
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Re: Suggestion, Super-streamlined, and Lifting hulls.

Postby phavoc » Mon Dec 21, 2015 9:07 pm

Only problem is that if it's a habitable world with any sort of TL, asteroids aren't going to be an issue as they can be blasted out of the sky, or nudged off course.

But I don't think any star-faring population is going to be too happy about even a 100Dton asteroid coming into the atmosphere. They have a tendency to do bad things. It is theorized the Tuskunga meteor was only about 120ft across. The Chelyabinsk meteor was only about 60ft across and when it detonated in the upper atmosphere it was "only" about 500 Kt... Though I suppose you could sneak up on a planet in the same way The Chelyabinsk meteor did.. but I'd think it would be better to use your anti-grvs and slowly drop into the atmosphere. Either way any populated world above TL6 or so should pick you up on radar or visual before you got close. Even lower-tech worlds may import scanning sats to pick up the TL slack.

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