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DEPLOYABLE FLAPS AND LIFT


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4 hours ago, Veeltch said:

The problem is that if you put these "flaps" in the same axis the CoG is then you just made yourself elevator control surfaces. I've built enough planes in FAR and played IL-2 for long enough to know how flaps should work. And they clearly don't work in KSP because the control surfaces and wings put together don't act as one solid body.

Thats my finding too. Deploying "flaps" (as they are in ksp) change a plane's geometry and, depending on where you place them, emulate some of the effects of a flap. But do not increase a wing's total lift, which should be its primary function.

5 hours ago, DualDesertEagle said:

 Or I give them Spoilerons, which in their deployed state decrease the lift at the normal angle of attack and thus force u to land with the nose raised, still slowing the plane down and ensuring that the main gear touches down first. That is often useful when there's delicate stuff on the front that shouldn't be harmed.

(...)

Also, I threw together an example real quick, one that comes closest to a normal private pilot's plane, and look how the CG is almost at the trailing edge of the wings instead at the 1st third of the wing like it should be. The reason why is that the center of lift is there too and I need to keep them close to each other in order to make a plane that works. Granted, when I deploy the flaps on this it does want to pitch down a little due to the CG and CoL being in front of the flaps, but that's nothing that makes the plane dive hard or can't be neutralized by the SAS. I didn't screen cap this coz right now I can't and I don't think it's really necessary right now.

exampleoip7f.png

Agreed on the first part. That is what I've been using them for too. My typical heavy duty airplane has three control surfaces in a wing:  ailerons in the tip (duh!), a upward deploying spoiler in the middle, and a downward deploying spoiler in the base. This way both spoilers counteract eachother and do not affect geometry, whilst breaking the hell out of the plane.

As to part two quoted above, yeah, and KSP has an aditional problem: everything generates lift. In real life planes, elevators in a conventional design (like your example plane) do not generate lift. But in KSP they will. All control surfaces do, unlike RL. Thats a problem! For starters, CoL will fall behind, creating some unwanted design necessities!

Edited by Daniel Prates
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Funnily enough, I was playing with just this kinda stuff yesterday... and getting frustrated. 

If you hit "Deploy" then, as far as I can tell, it sets a control surface to it's max deflection. You can visually change the amount of flaps with the Authority Limiter, but this does nothing practically, the flap's lift remains at max, though this can be reversed with "Deploy Direction". 

What I want to happen is to be able to lock a flap, then adjust the angle with a slider. This way I could potentially adjust the angle of attack of a craft in flight or deploy a flap then adjust the amount it is locked at. 

Edited by Foxster
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12 minutes ago, Foxster said:

Funnily enough, I was playing with just this kinda stuff yesterday... and getting frustrated. 

If you hit "Deploy" then, as far as I can tell, it sets a control surface to it's max deflection. You can visually change the amount of flaps with the Authority Limiter, but this does nothing practically, the flap's lift remains at max, though this can be reversed with "Deploy Direction". 

What I want to happen is to be able to lock a flap, then adjust the angle with a slider. This way I could potentially adjust the angle of attack of a craft in flight or deploy a flap then adjust the amount it is locked at. 

I'm pretty sure that if you set authority limit in SPH ,  when you "Deploy" that is the angle you get.   However,  changing authority in flight affects only the max deflection when acting as control surface, when Deployed they remember this function set in SPH?

Funnily enough,  I started work on a cruder version of what you describe more or less in parallel.

I often design my spaceplanes with built in wing incidence, intended to be flown with near-zero body aoa.   Note that when you set prograde hold on the SAS, it does not in fact give exactly zero aoa, but it applies a correction factor.  For example, if you craft flies hands off at -5 AoA with no control input, SAS will apply uptrim and reduce the error to only -1.  If it's set up to fly hands off at +5AoA, you'll get +1 on Prograde hold.   It's a feed back correction system that's imperfect and can only reduce , not eliminate the error.

Note that when you activate Prograde hold any pitch trim inputs you've made are ignored.

Which brings me back to my point.    By having a surface I can deploy, i can change the "hands off" natural AoA of the craft, and therefore the one that it settles at when Prograde hold is set.

So,  towards the end of the subsonic climb, we're nearing the transonic high drag zone.   I "deploy" the surface, and my airplane now settles into an AoA that's a couple of degrees higher.   This makes it climb more and delays the onset of the sound barrier.   When it arcs over the top from this climb and starts approaching transonic,  i toggle the deploy off again, and it settles to a lower AoA, and shallow dives through the sound barrier.  I can also use this to damp out phugoid oscillations while keeping prograde hold on.     

Plane starts overheating during hypersonic climb? Deploy, to get more nose up attitude and climb faster.

For re-entry, i'll leave them deployed to re-enter at a slightly higher aoa (coming in prograde gets rather hot)

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I occasionally strap Big-S elevons to the undersides of my main wings, square on the CoM (or just a hair off) and tuned down to avoid stalling. Simply adding more main wing is usually more effective (lighter, can store fuel if you use certain parts, etc) but there's some reason you can't (looks, wing fragility, whatever), it's an option. It doesn't work like flaps should work, but it does provide additional lift and drag, which means you can land lower and slower and slow down faster once you're down.

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  • 3 weeks later...
On ‎19‎/‎02‎/‎2017 at 9:00 PM, AeroGav said:

 

Funnily enough,  I started work on a cruder version of what you describe more or less in parallel.

I often design my spaceplanes with built in wing incidence, intended to be flown with near-zero body aoa.   Note that when you set prograde hold on the SAS, it does not in fact give exactly zero aoa, but it applies a correction factor.  For example, if you craft flies hands off at -5 AoA with no control input, SAS will apply uptrim and reduce the error to only -1.  If it's set up to fly hands off at +5AoA, you'll get +1 on Prograde hold.   It's a feed back correction system that's imperfect and can only reduce , not eliminate the error.

Note that when you activate Prograde hold any pitch trim inputs you've made are ignored.

Which brings me back to my point.    By having a surface I can deploy, i can change the "hands off" natural AoA of the craft, and therefore the one that it settles at when Prograde hold is set.

So,  towards the end of the subsonic climb, we're nearing the transonic high drag zone.   I "deploy" the surface, and my airplane now settles into an AoA that's a couple of degrees higher.   This makes it climb more and delays the onset of the sound barrier.   When it arcs over the top from this climb and starts approaching transonic,  i toggle the deploy off again, and it settles to a lower AoA, and shallow dives through the sound barrier.  I can also use this to damp out phugoid oscillations while keeping prograde hold on.     

 

I finally got round to modifying one of my existing SSTOs with this tech.

There is a video of the flight here,  and a link to the craft file if you want to try it yourself.   Worked pretty well I think ,  I might try shooting a video of flying the plane to orbit entirely from IVA mode next, never done that before but you literally have so little to do now as a pilot, I can't see how it would cost you anything.

 

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  • 3 years later...

Google translation:

Thank you !!!

It works well and it decreases the stall speed by about 25-30% but on the other hand it does not increase the stability.

Welcome to the forum, @Lucky_Gaming! The recommended language in the forum is English, but there's an international section where you can post freely in French.

Also, this is a necro post (a very old post, last comment was from 2017). Probably the people involved moved on.

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