thrust

[Romflyer 25]

Is there a way to adjust the flight model of an aircraft so that when I spool up the throttle the nose wants to pitch up, and when I reduce the throttle the nose relaxes back down?.........yes I have the emulated trim functioning........but I would like the sim to force me to use it

 

Cheers

Romflyer

[Fubar512 1,350]

Assuming that you're talking about jets, thrust position and thrust angle. The first should be set right around the position of the afterburner and/or exhaust emitter for that engine. The second should be adjusted very carefully (if at all), as it effectively directs the thrust at an offset angle.

[Romflyer 25]

My question was predicated on my assumption that jets will respond to throttle (thrust) settings similar to propellor driven aircraft, the more you open the throttle the more the nose of the aircraft pitches upward, which is the reason you need to trim.......what I was wondering is whether or not it is possible to get jets in Strike Fighters to respond to throttle settings the same way........could the flight model of a plane be made so that the amount of lift generated by the wing is variable to the amount of thrust (throttle setting)...........I guess I probably should have posted this in the modding forum.

[Fubar512 1,350]

My question was predicated on my assumption that jets will respond to throttle (thrust) settings similar to propellor driven aircraft, the more you open the throttle the more the nose of the aircraft pitches upward, which is the reason you need to trim.......what I was wondering is whether or not it is possible to get jets in Strike Fighters to respond to throttle settings the same way........could the flight model of a plane be made so that the amount of lift generated by the wing is variable to the amount of thrust (throttle setting)...........I guess I probably should have posted this in the modding forum.

 

I've just explained to you how it can be done.

[Romflyer 25]

I've just explained to you how it can be done.

 

 

My apologies..........this is where my inexperience becomes blaringly obvious

 

 

ThrustAngles=0.0,0.0,0.0

ThrustPosition=0.00,-4.825,-0.065

 

Now that I understand what your answer meant I'm thinking that adjusting the thrust angle would be the most effective choice.........but in reading your earlier post it sounds like you thought thrust position to be a better choice???

 

 

[Fubar512 1,350]

Let's use the F-4 Phantom as an example.

 

The exhaust position entries for may be "ThrustPosition=-0.65,-3.63,-0.58 and ThrustPosition=0.65,-3.63,-0.58" (L & R).

 

The F-4 has it's tailpipes canted down, so one might use the following for the thrust angle settings:

ThrustAngles=0.0,-3.60,-0.5 (remember x,y,Z coords). This would make the aircraft's nose pitch down when power is applied.

[Romflyer 25]

Let's use the F-4 Phantom as an example.

 

The exhaust position entries for may be "ThrustPosition=-0.65,-3.63,-0.58 and ThrustPosition=0.65,-3.63,-0.58" (L & R).

 

The F-4 has it's tailpipes canted down, so one might use the following for the thrust angle settings:

ThrustAngles=0.0,-3.60,-0.5 (remember x,y,Z coords). This would make the aircraft's nose pitch down when power is applied.

 

Thanks Fubar

The example I used was from the F-16, I was thinking about adjusting the last set of zeros to 0.01 and then see what happens.

 

ThrustAngles=0.0,0.0,0.0

ThrustPosition=0.00,-4.825,-0.065

 

Of course I'm gonna play with those numbers, and then I'll probably be back asking how to adjust the angle of the elevator to compensate for the change in thrust angle

Thanks again for your time Fubar

Cheers

Romflyer

[Romflyer 25]

Well I tried it out last night in my F-18, started with thrust angle at 0.01.......kept on adding and adding, more and more.......finally gave up at 10.5 and figured I was spending too much of my rare flight-time on something that seemed to be going no where ......I really thought we were on to something.

[FastCargo 412]

First, why would you assume adding thrust automatically causes a nose to pitch? If the engines are located close to or on centerline, you won't get a pitching moment.

 

Second, I'm pretty sure a lot of modern fighters have auto trim that would cancel out such effects.

 

Third, are you sure you were adjusting the pitch and not the roll axis?

 

Fourth, if you are dead intent on creating this effect, just add an invisible engine with no exhaust that has lots of pitch thrust.

 

Fifth, realize that if you add this, any AI aircraft will have to deal with it too, which means you may actually hamper their abilities in flight.

 

FC

[Romflyer 25]

First, why would you assume adding thrust automatically causes a nose to pitch? If the engines are located close to or on centerline, you won't get a pitching moment.

 

Second, I'm pretty sure a lot of modern fighters have auto trim that would cancel out such effects.

 

Third, are you sure you were adjusting the pitch and not the roll axis?

 

Fourth, if you are dead intent on creating this effect, just add an invisible engine with no exhaust that has lots of pitch thrust.

 

Fifth, realize that if you add this, any AI aircraft will have to deal with it too, which means you may actually hamper their abilities in flight.

 

FC

 

1) As I said in my second post in this thread that I am assuming that jets would react similar to propellor driven aircraft.......perhaps lowering the thrust position to be below the centerline (as Fubar said at the beginning) might yield better results........would changing thrust position only effect the physics of thrust location, or would it also effect the external visual model?

 

2) Yes, maybe some of them do.........it is my understanding that most (if not all) jets have some form of manual trim (again I am assuming) ......Has it not been your experience in real life aviation, that when you change a throttle setting you need to adjust your trim in order to maintain "straight and level flight"?......

 

3) I was adjusting the third value in the string, it would make sense that it was the correct one to adjust.....there seemed to no change in pitch or yaw

 

4) I wouldnt say that I am dead set on this.......more like curious.

I would have thought that if it would work on a third invisible engine, then it should have worked on the two existing engines??

 

5) Well, if I do get it to work, then it will be interesting to see what the AI does with it........

 

Its all just a big experiment, trying to make my sim experience as good as I feel it can be thats what makes this fabulous hobby so fun!!

 

 

 

[FastCargo 412]

1) As I said in my second post in this thread that I am assuming that jets would react similar to propellor driven aircraft.......perhaps lowering the thrust position to be below the centerline (as Fubar said at the beginning) might yield better results........would changing thrust position only effect the physics of thrust location, or would it also effect the external visual model?

 

2) Yes, maybe some of them do.........it is my understanding that most (if not all) jets have some form of manual trim (again I am assuming) ......Has it not been your experience in real life aviation, that when you change a throttle setting you need to adjust your trim in order to maintain "straight and level flight"?......

 

3) I was adjusting the third value in the string, it would make sense that it was the correct one to adjust.....there seemed to no change in pitch or yaw

 

4) I wouldnt say that I am dead set on this.......more like curious.

I would have thought that if it would work on a third invisible engine, then it should have worked on the two existing engines??

 

5) Well, if I do get it to work, then it will be interesting to see what the AI does with it........

 

Its all just a big experiment, trying to make my sim experience as good as I feel it can be thats what makes this fabulous hobby so fun!!

 

1. Jet's will go out of trim because of SPEED, not because of thrust if the engines are close to or on centerline at high speed...like most modern fighters. I have plenty of real world experience in this regard.

 

2. See the answer to question #1. Most modern aircraft have an auto-trim mode. You can manual trim if you want...I don't find it interesting because it's natural like walking.

 

3. You are adjusting the wrong parameter, try again. I have done plenty of work in this regard when working on the F-22 and F-15 ACTIVE. Adjusting thrust angles will affect the aircraft and how it handles. Adjusting the thrust position will do the same thing. And yes, the flight model takes this into account.

 

4. See the answer to question #3. Also, adjusting the thrust angles does adjust the visual effect direction...so if you don't want a cocked off exhaust plume, best to add another engine.

 

5. The answer is, the AI will try to keep the aircraft in a flyable area of the envelope. The AI does not do post=stall manuvering other than to try to get out of the stall. If you're expecting the AI to do cobras, wingovers, etc, it won't happen...at least not to the point of trying to defeat an opponent. This is why I've found things like manual trim, manual thrust vectoring, manual wing sweep, backwards firing missiles to be worse than useless, because the AI will not take advantage of ANY of it. At that point, you're basically in Ace Combat mode, and unless you're doing multiplayer, quickly takes all the fun out of it...clubbing baby seals as it were.

 

Experimenting is fine, that's what makes it interesting. But know why something works first.

 

FC

[Romflyer 25]

1. Jet's will go out of trim because of SPEED, not because of thrust if the engines are close to or on centerline at high speed...like most modern fighters. I have plenty of real world experience in this regard.

 

2. See the answer to question #1. Most modern aircraft have an auto-trim mode. You can manual trim if you want...I don't find it interesting because it's natural like walking.

 

3. You are adjusting the wrong parameter, try again. I have done plenty of work in this regard when working on the F-22 and F-15 ACTIVE. Adjusting thrust angles will affect the aircraft and how it handles. Adjusting the thrust position will do the same thing. And yes, the flight model takes this into account.

 

4. See the answer to question #3. Also, adjusting the thrust angles does adjust the visual effect direction...so if you don't want a cocked off exhaust plume, best to add another engine.

 

5. The answer is, the AI will try to keep the aircraft in a flyable area of the envelope. The AI does not do post=stall manuvering other than to try to get out of the stall. If you're expecting the AI to do cobras, wingovers, etc, it won't happen...at least not to the point of trying to defeat an opponent. This is why I've found things like manual trim, manual thrust vectoring, manual wing sweep, backwards firing missiles to be worse than useless, because the AI will not take advantage of ANY of it. At that point, you're basically in Ace Combat mode, and unless you're doing multiplayer, quickly takes all the fun out of it...clubbing baby seals as it were.

 

Experimenting is fine, that's what makes it interesting. But know why something works first.

 

FC

 

 

1) I'm curious to know why this differs in jets to most other aircraft.......is it just because of centerline thrust, or is it also related to AOA on the wing?

 

2) It's not about me thinking trimming is fun.......it's about me thinking that needing to trim is more realistic.........I have the highest of respect in your opinion on these matters, and you do have me wondering about some of the assumptions I am making about the need within the game for this function.

 

3) I wish I could think of something to say

 

4) see answer 3

 

5) I wasnt trying to get AI to do anything .......as a matter of fact I hadnt even thought about the effect on AI until you brought it up. And I wasnt trying to soup up a plane so I could pretend I was in some sci-fi shootem up game (not my thing). I have just been toying around with trying to get a small piece of realism that I thought the sim was missing..........And lets be clear about this, I am not complaining ..........I'm learning.

 

And I do appreciate you taking the time to share your knowledge

 

 

 

[FastCargo 412]

1. Jets are subject to the same laws of physics as any other aircraft. The difference is that we are talking about a very specific case...jet fighters, where most of the time, the engine thrust vector passes straight through the CG. Jet airliners on the other hand, if you goose the throttle, you will get a pitch up moment (try doing a single engine go-around in a modern jetliner...it's Mr. Toad's wild ride right there) because the engine thrust vector is signifcantly displaced from the CG. For props, other issues creep up, including things like P-factor, etc.

 

3. and 4. Don't know what to tell you, you're adjusting the wrong parameter.

 

Here's a test I just did while working on something else on the F-111...I adjusted the thrust angles on each engine by 10 degrees - Left engine 10 degrees pitch up, right engine 10 degree pitch down:

 

 

It took me longer to post this than it took to do it.

 

5. If you really want to make an aircraft act more appropriately that requires trim, a better and more appropriate way to do it I believe is to mess with the Xac tables in the data.ini. Fubar512 is the person to ask about it.

 

FC

[Romflyer 25]

1. Jets are subject to the same laws of physics as any other aircraft. The difference is that we are talking about a very specific case...jet fighters, where most of the time, the engine thrust vector passes straight through the CG. Jet airliners on the other hand, if you goose the throttle, you will get a pitch up moment (try doing a single engine go-around in a modern jetliner...it's Mr. Toad's wild ride right there) because the engine thrust vector is signifcantly displaced from the CG. For props, other issues creep up, including things like P-factor, etc.

 

3. and 4. Don't know what to tell you, you're adjusting the wrong parameter.

 

Here's a test I just did while working on something else on the F-111...I adjusted the thrust angles on each engine by 10 degrees - Left engine 10 degrees pitch up, right engine 10 degree pitch down:

 

 

It took me longer to post this than it took to do it.

 

5. If you really want to make an aircraft act more appropriately that requires trim, a better and more appropriate way to do it I believe is to mess with the Xac tables in the data.ini. Fubar512 is the person to ask about it.

 

FC

 

When I said jets, yes I meant jet fighters.......doing a go-around is exactly what I am basing my expectations on, havent done it in a real jetliner, allthough I've done my fair share in small piston GA.......and Ive assumed that similar if not stronger requirements for forward pressure on the stick would be required with that much more horsepower kicking you in the.....butt.

From everything you are telling me I'm not sure that pursuing this too much further is worth.....asking for. Unless someone like Fubar feels a need to make those kind of changes.

 

Thank you again for sharing.

 

Romflyer