Updated Vehicle Handbook in the works

[tytalan]

Moving an object directly opposite of gravity is only one of an infinite number of possible vectors, about half of which will work with the force of gravity to increase an object's downward motion, and about half of which will have to work against gravity.

In all cases, F = ma remains unchanged. The amount of acceleration any given mass exhibits is directly proportional to the sum of all Forces acting on it. You are confusing the final vector (e.g. gravity + external force = possible lift) with the individual F = ma calculations.

Here's an example. Assume gravity of 1G, and 1 unit of mass. There is a constant downward acceleration vector of F = 1 / m = 1, or 1 m/s^2.

If I apply an upward force of 0.5G to that mass, then it will accelerate upward at a rate of 0.5/1, or 0.5 m/s^2, for a final vector that is still falling downward, but now at only half the rate. I'm still accelerating the object according to F = ma, just not enough to fully overcome gravity.

If I applied that same force perpendicularly, the object would now have a downward vector of 1 m/s^2 PLUS a horizontal vector of 0.5 m/s^2 (ignoring friction) - I didn't have to overcome gravity at all, which is why you can push more than you can lift (when gravity is a significant factor).

That same principle applies even if you totally remove gravity - I can still only accelerate that mass at 0.5 m/s^2 because the amount of Force I can apply has not changed.

Maybe it will help if I use your own example.
So back to the box if I apply 2 units of force with gravity of 1 unit countering I get acceleration of 1 unit. But if I apply 2 units without gravity I get 2 units of acceleration.

Now let’s slide the box if I apply 2 units of force to slide the box with gravity of 1 unit and friction of say .5 units I only have to counteract part of the unit of gravity since I’m not going directly against it so for simplicity sake we say with the vectors the effect of the gravity is .5 in this case so I accelerate 1 unit to the left if we remove gravity I’m only countering the force of friction so I move the box 1.5 acceleration to the left. If the box is in the air so we eliminate friction (yes I know there are other forces but I’m keeping it simple) the acceleration of the wind is now 2 instead of say the 1.5 we had with gravity( these numbers are no where near correct but we are going for simplicity) meaning the wind is now having a greater effect.

Now for dis structure we have the wind pushing different parts of the ship in different directions and with different forces some of those directions and forces are change very rapidly this can cause torque effects that can rip the ship apart.

 

[coolAlias]

Maybe it will help if I use your own example.
So back to the box if I apply 2 units of force with gravity of 1 unit countering I get acceleration of 1 unit. But if I apply 2 units without gravity I get 2 units of acceleration.

Now let’s slide the box if I apply 2 units of force to slide the box with gravity of 1 unit and friction of say .5 units I only have to counteract part of the unit of gravity since I’m not going directly against it so for simplicity sake we say with the vectors the effect of the gravity is .5 in this case so I accelerate 1 unit to the left if we remove gravity I’m only countering the force of friction so I move the box 1.5 acceleration to the left. If the box is in the air so we eliminate friction (yes I know there are other forces but I’m keeping it simple) the acceleration of the wind is now 2 instead of say the 1.5 we had with gravity( these numbers are no where near correct but we are going for simplicity) meaning the wind is now having a greater effect.

Now for dis structure we have the wind pushing different parts of the ship in different directions and with different forces some of those directions and forces are change very rapidly this can cause torque effects that can rip the ship apart.

Will the wind shear be less on the ground due to friction? Yes (among other reasons it would be less).

Will the wind shear be more in the air if the ship/structure has lifters installed? No. It would still be 2.0 in your example, whether gravity is in play or not (unless it is actually falling, in which case there would be some wind shear from that vector as well).

 

[Vormaerin]

Wind shear is primarily dangerous because it disrupts the airflow around an aircraft, reducing its lift. It might, if strong enough, cause other deviations in intended course which require correction.

Lifter based ships are not reliant on airflow for lift. And, unless there is another object around for them to be pushed into, there's not really a lot of concern about a horizontal vector making your upward path diagonal instead of straight.

 

[Libris]

I got what tytalan was trying to get across which if I’m not mistaken essentially boils down to if you’re not having to worry about all that gravity nonsense then you can use the power that was needed to counteract it for something else - like more acceleration.
A good, but not perfect, example would be a helicopter where you are having to devote a fair amount of power just to stay aloft.

 

[MasterGwydion]

Wind shear is primarily dangerous because it disrupts the airflow around an aircraft, reducing its lift. It might, if strong enough, cause other deviations in intended course which require correction.

Lifter based ships are not reliant on airflow for lift. And, unless there is another object around for them to be pushed into, there's not really a lot of concern about a horizontal vector making your upward path diagonal instead of straight.

Unless the gusts flip your ship over. Then your lifters are doubling your acceleration to the ground.

 

[coolAlias]

I got what tytalan was trying to get across which if I’m not mistaken essentially boils down to if you’re not having to worry about all that gravity nonsense then you can use the power that was needed to counteract it for something else - like more acceleration.
A good, but not perfect, example would be a helicopter where you are having to devote a fair amount of power just to stay aloft.

Oh yeah, for sure, depending of course on how much power the lifters themselves require (I have no idea).

Any extra power you do get could power your thrusters, and thus apply more thrust force for greater acceleration, regardless of your choice of vector.

 

[coolAlias]

Unless the gusts flip your ship over. Then your lifters are doubling your acceleration to the ground.

That's why smart ship-builders install omni-directional lifters - they've heard about High n' Dry, they know what's coming.

 

[MasterGwydion]

That's why smart ship-builders install omni-directional lifters - they've heard about High n' Dry, they know what's coming.

Could be that ships not designed for planetary landings don't have omni-directional lifters. Maybe that is one of the reasons they are riskier to try and land? Since it doesn't really say anywhere, I guess this explanation is as good as any...lol...

 

[coolAlias]

Could be that ships not designed for planetary landings don't have omni-directional lifters. Maybe that is one of the reasons they are riskier to try and land? Since it doesn't really say anywhere, I guess this explanation is as good as any...lol...

I don't think omni-directional lifters are a thing, but if they were, I'm imagining the ships end up looking like this:

 

[Condottiere]

You have other options.

 

[Vormaerin]

Oh yeah, for sure, depending of course on how much power the lifters themselves require (I have no idea).

Any extra power you do get could power your thrusters, and thus apply more thrust force for greater acceleration, regardless of your choice of vector.

Part of the problem that started this discussion is that lifters just magically appear on ships and have no cost independent of the hull in MgT2e post Starship Operator's Manual.

In some other versions of Traveller, like T:NE, lifters took up volume and surface area and had a cost. Which makes more sense.

Anyway, it is certainly true that removing the gravity vector leaves more power to spend on other factors, but that's not actually relevant to the point that started this conversation. Which was about how lifters make non aerodynamic ship configurations not the problem that the rules say they are, because you aren't reliant on airflow for any of your lift and you aren't required to fly into the wind or any other maneuver that might cause excessive friction or stress on the structure.

 

[Condottiere]

Hybrid propulsion could leverage the strengths of each, and minimize the weaknesses.

Since lifter rules aren't clearly spelled out, this is mostly speculation.

They're probably an upscaled version of whatever makes the air/raft effervescent.

 

[MasterGwydion]

Part of the problem that started this discussion is that lifters just magically appear on ships and have no cost independent of the hull in MgT2e post Starship Operator's Manual.

In some other versions of Traveller, like T:NE, lifters took up volume and surface area and had a cost. Which makes more sense.

Anyway, it is certainly true that removing the gravity vector leaves more power to spend on other factors, but that's not actually relevant to the point that started this conversation. Which was about how lifters make non aerodynamic ship configurations not the problem that the rules say they are, because you aren't reliant on airflow for any of your lift and you aren't required to fly into the wind or any other maneuver that might cause excessive friction or stress on the structure.

Wind is still a thing. Coming slowly into Earth's atmosphere wouldn't really help you either since you are still passing through zones with winds up to almost 500kph. Being aerodynamic does help with this. So, the original premise was that lifters remove the need for being aerodynamic, but in 500kph winds, I disagree. BTW. Google average windspeed at 60,000ft. It is telling Me that it is a range from 278-463kph. Other altitudes and other planets will vary, of course.

 

[Sigtrygg]

So you match speed with the wind using the maneuver component of your maneuver drive, if the wind is moving at 300kph and so are you what is your relative velocity?

The air is not moving relative to you so there is no wind. Ok so relative to the ground you are moving at 300kph but so what? The lifters allow you to slowly fall to the ground, your maneuver drive maintains parity with wind speed, once yo get close to the ground you use your maneuver drive to slow down, keep the liters on and you don't even have to land, you can stay 10cm off the ground.

This is not how I have ever thought of Traveller ships landing, but with lifters now being standard it is how it is done.

 

[MasterGwydion]

So you match speed with the wind using the maneuver component of your maneuver drive, if the wind is moving at 300kph and so are you what is your relative velocity?

The air is not moving relative to you so there is no wind. Ok so relative to the ground you are moving at 300kph but so what? The lifters allow you to slowly fall to the ground, your maneuver drive maintains parity with wind speed, once yo get close to the ground you use your maneuver drive to slow down, keep the liters on and you don't even have to land, you can stay 10cm off the ground.

This is not how I have ever thought of Traveller ships landing, but with lifters now being standard it is how it is done.

They are not exactly designed to deal with 200kph gusts either. Your plan only works if the wind stays at a constant speed, which it never does.

 

[Sigtrygg]

Trade winds are pretty constant, and a 1g maneuver drive is more powerful than most jets. Any weather you don't think you can match speed wise you stay out of.

300kph is nothing compared to reentry speeds of real world orbital vehicles.

 

[J. L. Brown]

I'm lifting, er, taking, Lifters strait from T5: slow, but it can gain altitude. No need to diverge, but it does eventually get you above the atmosphere if you are patient. More a secondary transport mode, or something for your 'flying' house, not your air/raft.

So what distinguishes a Lifter from a Maneuver-0 drive with the 'Orbital Range' restriction? Would a 'Budget' (requires exactly one disadvantage) Man-0 with the 'Orbital' limitation (2 disadvantages) be able to take the 'Energy Efficient' (1 advantage) to bring it to the required 1 net disadvantage?

 

[Geir]

So what distinguished a Lifter from a Maneuver-0 drive with the 'Orbital Range' restriction? Would a 'Budget' (requires exactly one disadvantage) Man-0 with the 'Orbital' limitation (2 disadvantages) be able to take the 'Energy Efficient' (1 advantage) to bring it to the required 1 net disadvantage?

Err... if you allow mixing of advantages and disadvantages, then yes. Not redoing High Guard, though. So in a system built up from scratch, it would be easier to scale from an eBike to a Tigress, but we're not there this time around.

 

[J. L. Brown]

Err... if you allow mixing of advantages and disadvantages, then yes. Not redoing High Guard, though. So in a system built up from scratch, it would be easier to scale from an eBike to a Tigress, but we're not there this time around.

So what distinguishes a Lifter from a Maneuver-0 drive with the 'Orbital Range' restriction?

I'm interested in how they compare. If the official stance is that Man-0 includes 'Lifters' for all ships, then vehicles with 'Lifters' ought to make sense in comparison; and I am wondering exactly how they stack up against each other.

 

[Condottiere]

Factor/zero is basically orbital corrections.

Going by other developments, maybe acceleration 0.01.