# Aircraft Acceleration physics

I’m making a simulation of a P51 Mustang. I’ve got the angle of attack, with which I’ve got the Drag and Lift with their Coefficients(all from the NASA website:spin:). So all the external forces are done. But what I need is some good Thrust Physics. ATM my aircraft just takes off in 3 seconds. But I need some calculations that will give a good effect. As we know, acceleration builds up, and it takes time for the aircraft to take off. So what I need is:

• Thrust build-up physics
• Flap physics (I understand that the wing area changes the value, but how do you calculate that?)
• Undercarriage Physics

If you can, provide a source.

Very simple one
Thrust = ( prop efficiency * power ) / speed

That…was awesome…

The plane model looks very good. The gun-sight ‘No hand hold’ texture need to rotate.

The texture panel lines are thick but those actually look good from some distance.

I did not found yet a good write up about flaps physics.

From top of my head. The flaps change a the wing effective shape and some design adds a wing area too, causing a more lift with more drag and nose down momentum.

The picture is just a rough idea

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Thanks that helps alot Xjazz(although is is very complicated and I am only in Yr 10).
More people have a look and comment plz, its all appreciated.
Any other developments appreciated.
Keep this thread going!

Ive been looking around everywhere and have been getting more confused on what equation to do for my propeller efficiency as some are extremely complicated! Some demand the static pressure etc. etc. and some do the thrust directly. I am really confused! What is the easiest ACCURATE equation for propeller efficiency?

Hi

There’s no easy AND accurate formula for the propel. At least I did not found one yet.

I use this very simple thrust formula for my project until I get the flight model more or less done.
Thrust = (prop efficiency * power ) / speed

The power, mass and drag of the plane need to be in correct scale.

I’ve got the prop efficiency, and I’ve got the Rest as wel :)l. I will scale all my forces by 10 as the mass is 3465 kgs, and all the calculations are based on force per Newton (and as the BGE can’t calculate anything over a mass of 10,000 I thought just scaling down all the forces would be easier). The Controls are next. I have a question: How will I create stall? I thought of creating a stall and spin animation that starts when the aircraft speed goes under *** at a rate of *** (oh bother I’ll have to get calculations for that as well :()

Hi Eaglestrike,

Good to hear you solve the problem.

I didn’t know the bge can’t handle over 10000 weights. Thanks for the info.

Stalls
The stall is not depending from the speed, it’s depending the angle of attack. That’s why you can stall at any speed… If you have enough control authority.

Search from this document with ‘Stall’ and ‘Accelerated stall’

Common practice in flight sims is to have audio(rumble) and visual(shake) feedback, when you are reaching the high aoa’s before the stall.Some planes stalls harder & wilder than others.

Download a Aces High 2 (127M). It’s free for the offline flying. Just disable the ‘Stall limiter’ from the flight options menu and check how the stalls are done there.
http://www2.hitechcreations.com/frindex.html

Like Xjazz said stalls depend on the wings aoa. Simple stalls are as easy as multiplying lift by a small number once the wing’s aoa is over a certian constant [usually around 15 degrees], although spin stalls are harder as they depend on variation in each wings aerodynamics and air pressure.

Another great reference for flight sims is the IL2 Stormovik demo ( http://download.cnet.com/IL-2-Sturmovik-demo/3000-7544_4-10230098.html ) which, although quite old, has a verry impressive flight model.

I’ve got IL2 Sturmovik, its a cool game :)(although I always thought that the take offs were too over realistic). I’m getting AH2 (I had an older version, prob deleted it). I brb with an upload you guys can see. Is there a nice tutorial on environment modelling? I don’t have much experience with modelling terrain. And how can you get those real nice water effects? I was hoping to get a nice mission in about 2-3 months time. Thanks alot and keep me updated.

bad news guys - something glitched (by that I mean that I made a Huge Error:() and I’ve had to redo all my physics. Ive got Lift and Drag, but Thrust and Efficiency are screwed. Problem is that for the Lift and Drag I’m using the NASA calculations, and for the Thrust im using http://www.mh-aerotools.de/airfoils/propuls4.htm. Now, It hasn’y explained what velocity of the incoming flow and propeller accelaration are. And as I haven’t done these in school I haven’t a clue on how to calculate them. I could assume that prop acceleration is rpmxprop swept area but I can’t risk screwing again. If I get these two values then the rest would be easy. If someone could help then it would be great otherwise ill be stuck for a while :(.

Well, I really don’t get any of these calculations. Theres the NASA ones, and the ones that want prop efficiency. If someone could direct me to the right one then it would be appreciated!!

anyone help me? (Yes I am looking for the answer myself)

You might have already tried this, but the community at physicsforums.com is super helpful. I guarantee if you posted there you’d get the best answer.