[1.3.1] Ferram Aerospace Research: v0.15.9.1 "Liepmann" 4/2/18

[Goozeman]

A real quick question about units. The aircraft I'm currently flying has a single basic jet engine. While flying at 22km, the TSFC is listed as 0.750/s. This is absolutely absurd, as it would be consuming 3/4 of it's thrust in fuel every second. I'm guessing that this should be 0.750/hr, which would make sense and be inline with real engines.

[pasty2k2]

Hey ferram, thanks for the reply - I thought fairings did nothing to the aerodynamics of the parts within, it's all calculated as if no fairing were there? Unless specific ones do, or all do with FAR installed, or it changed, or I'm wrong ha...

Thanks - will try it out!

[Camacha]

Hey ferram, thanks for the reply - I thought fairings did nothing to the aerodynamics of the parts within, it's all calculated as if no fairing were there? Unless specific ones do, or all do with FAR installed, or it changed, or I'm wrong ha...

Fairings actually work with FAR, as well as nosecones. So no nasty looking stocklike vehicles I believe FAR detects fairings through how they are called.

[ferram4]

@Goozeman: Indeed, that's correct. I derped when I was running through the units. It is now fixed in my dev version.

@pasty2k: Fairings don't do anything with the stock drag model; with FAR, if the fairing detects a part inside it that part is not affected by aerodynamics.

[camlost]

Ferram, i want to thank you for your mod! Actually, i even managed to remember my login and password for this...

Without your aerodynamic model this... thing... would never become airborne!

I just want to point out that this kind of "jet on blade" configuration doesn't require a tail rotor or being coxial, in RL. The only torque applied to the body is friction from the axis.

[Beetlecat]

Woah -- I just had my first experience with a VERY aerodynamic command pod reentry. The thing was flying sideways and even gained altitude at a couple points --WITH the main chute deployed.

Is there something special about the large 3-kerb pod, or did I just get a lucky set of circumstances?

I've only played with the mkI pod before, and it behaves far more expected-ly on reentry.

[jrandom]

Woah -- I just had my first experience with a VERY aerodynamic command pod reentry. The thing was flying sideways and even gained altitude at a couple points --WITH the main chute deployed.

Is there something special about the large 3-kerb pod, or did I just get a lucky set of circumstances?

I've only played with the mkI pod before, and it behaves far more expected-ly on reentry.

If you tilt to the right angle, large pods can generate a non-negligible amount of lift. This is a real thing -- see "lifting reentry".

[ferram4]

No, I think he's talking about far too much lift at subsonic speeds; the pod doesn't make that much lift at supersonic speeds if you deploy the chute early. I'll have to go through the math and make sure that everything is being done correctly.

Edit: Looking at some math, the potential lift calculation looks like it's too large. In any case, I was taking the integral of A wrt x from 0 to l rather than the integral of dA/dx wrt x from 0 to l, so things will be different (A is cross-sectional area, x is distance down the body, l is body length). How different, I don't know; I'll have to test.

Edited December 5, 2013 by ferram4

[bgryderclock]

@bgryderclock: Like everyone else said, it sounds like you're on a Mac. Did you read the part of the instructions where it said to merge the folders rather than to copy the folder over? The latter causes the original folder to be overwritten.

Yeah, it was Noob mistake, I copied instead of merging. The mod is working great. Good work Sir.

(P.S. I am running on Linux not a Mac)

[Beetlecat]

No, I think he's talking about far too much lift at subsonic speeds; the pod doesn't make that much lift at supersonic speeds if you deploy the chute early. I'll have to go through the math and make sure that everything is being done correctly.

Edit: Looking at some math, the potential lift calculation looks like it's too large. In any case, I was taking the integral of A wrt x from 0 to l rather than the integral of dA/dx wrt x from 0 to l, so things will be different (A is cross-sectional area, x is distance down the body, l is body length). How different, I don't know; I'll have to test.

That did seem to be the conditions --and I had opened the main parachute far too early due to a staging error. The perceived effect was that horizontal speed actually picked up, with the 'chute nearly horizontal behind the capsule.

Beyond this, I'm loving the changes brought by these modifications. If KSP teaches (many of) us the concept of a "Gravity Turn," FAR goes back and shows how it's really done. Thank you for your efforts at making this game a pretty darn good simulator!

[VFB1210]

If you tilt to the right angle, large pods can generate a non-negligible amount of lift. This is a real thing -- see "lifting reentry".

My time to shine! I actually made a video about doing this in KSP.

[forsaken1111]

So I've gotten around my heavy-lift flipout problem by including the payload in the MIDDLE of the rocket. Seems to work better.

[Goozeman]

A small request. The Rate of Climb indicator in the HUD is useful, but not for fine tuned maneuvering. Could you add a ROC line to the FAR Flight Data? Thanks.

[Vrana]

Until he does i belive the info you are looking for can be found in Kerbal Engineer. Surface tab - Vertical Velocity readout.

[ferram4]

@Beetlecat: Based on a few of my tests, I think the aerodynamics themselves are right, the issue is that the overpowered pod torque is capable of keeping it at that high an angle of attack. Basically, we'd be able to see this in real life if capsules actually had that kind of reaction wheel torque available combined with not having to worry about saturating the wheels.

@VFB1210: That's from FAR 0.9.7; pod lift wasn't properly implemented at that time, and was notably backwards.

@Goozeman: I can stick that in somewhere. I'll make it work.

[DragonEG]

I just want to point out that this kind of "jet on blade" configuration doesn't require a tail rotor or being coxial, in RL. The only torque applied to the body is friction from the axis.

You do not need to counter engine torque. You need to counter other forces, which will create roll moment if you gain forward speed. They are a result of different lift created by blades going forward and backward relative to aircraft speed (advancing and retreating respectively). They are called dissymmetry of lift and tail rotor won't help to counter them.

[Ghostbird]

How do I make flaps? Do I simply add control surfaces to the front of the wings/top of the wings and configure them as flaps?

Or do I need a mod for that? If so, what mods would you recommend?

[TheBrisbyMouse]

Help!

I'm trying to use the flight assistance and it's not doing anything!

I started noticing it when I first started playing with this mod about a week ago. I was trying to fly the Hypersonic Demon around Kerbin at 30Km and tried to give it a 6 degree maximum angle of attack. I watched as it went from 5 to 10 to 30 degrees and then flamed out, stalled, lost control, and finally lithobraked. I've been messing around with it a lot, and nothing seems to be able to control the aircraft. Is there a FAR Flight Assistance for Dummies out there? Or am I just a big noob?

[AbeS]

Are you using SAS? if it's on FAR doesn't do anything

[TheBrisbyMouse]

All my problems solved.

Except one.

Keeping your plane level using the flight assistance is a nightmare. It keeps your nose from deviating your selected value from PROGRADE, not the horizon. That was my problem time and time again. Perhaps there could be an option to change the reference point (horizon, prograde, where you set it)?

[Ghostbird]

Lvl flight assistance actually works for you? I thought it didn't work at all. I didn't notice any difference between using it and not using it. Then again, I don't use Mechjeb, since I can do the important manoeuvres better myself. Which probably just means that my vehicles are too weird for Mechjeb and FAR auto-pilots to handle.

I must say though. FAR finally makes planes handle-able. In stock KSP my planes would nearly always have crazy behaviour, and crash. Of course I managed that in FAR too, but it took me three revisions.

I still suck at landing my planes though. Therefore I attached sepratrons and parachutes to the cockpit, and I can shoot it away from the plane. Then I found out that with KAS (Kerbal Attachment System) installed, my Kerbals can carry radial mount parachutes. Even if those parachutes have been deployed, but not yet activated because of too low atmospheric density. From there I repurposed the plane to a STOL that flies to 25km on it's jets, then fires the liquid fuel rockets, then ejects the cockpit upwards. Before it reaches 90km apoapsis, I'll deploy the parachutes, the pilot will go on EVA, and grab one of the deployed parachutes. From there he goes skydiving. And lands safely.

[a.g.]

Lvl has nothing to do with prograde or anything, it stops the plane rolling and thus turning left or right.

[TheBrisbyMouse]

I mean level on the pitch axis.

[Traches]

All my problems solved.

Except one.

Keeping your plane level using the flight assistance is a nightmare. It keeps your nose from deviating your selected value from PROGRADE, not the horizon. That was my problem time and time again. Perhaps there could be an option to change the reference point (horizon, prograde, where you set it)?

Have you tried using pitch trim? It's not an autopilot, but if you trim it out it's hands-off flying. Your trim setting will tend to climb or dive to maintain a constant EAS, so you can control ascent/descent with thrust.

[ferram4]

@Ghostbird: Flaps are set up in the SPH / VAB, using the GUI that you probably minimized and forgot about immediately. The very first window that it shows lets you modify what the control surfaces do.

@TheBrisbyMouse: All of the flight assistance systems are set up the way they would on a plane, and are only intended to help make the plane more controllable; they are not intended to replace the pilot, hence "assistance." If you want to hold an orientation relative to the universe, SAS already does that.

If you want an explanation of what each system does, you can check under the Flight Assistance Settings -> Help; the reason that it is placed there is because I had worked on the assumption that a clueless person would first look under "Settings" to see if they could figure out what was going on based on the controls, and would then go to "Help" once there.

Frankly, I'm thinking of just stripping out the control systems since they always seem to cause more trouble than they're worth. Too many people get confused by them or blame them for their problems even when they're turned off. Or turn them on with SAS, and then complain that it doesn't do anything since they left SAS in control. It would also clean up FAR's focus, since it's intended to be an aerodynamics plugin, not a control systems plugin.