About asymmetric payload trim

In real world, when fighters are flying with asymmetric payload, how do pilot trim the plane? Do they use rudder trim or aileron trim？And why?

In real world, when fighters are flying with asymmetric payload, how do pilot trim the plane? Do they use rudder trim or aileron trim？And why?

I was wondering the same...

Tested "double ugly" cat launches today, sans targetting pod of course. You really need to dial in the correct amount of aileron trim to keep straight on launch. Any sort of guide or rule of thumb on this? Was around 24 - 36 on FCS page for aileron trim difference.

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Aileron trim. While the Hornet has automatic pitch trim, it does not have automatic roll trim.

Can we have asymmetric payload pounds-feet table on rearm page?

Or it's too hard for us to know how many differential degree to trim.

Tested "double ugly" cat launches today, sans targetting pod of course. You really need to dial in the correct amount of aileron trim to keep straight on launch. Any sort of guide or rule of thumb on this? Was around 24 - 36 on FCS page for aileron trim difference.

 

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It is mentioned in NATOPS/Charts available online. You have to calculate the weight on each wing. Does anyone have a list of the weights of each weapon?

It is mentioned in NATOPS/Charts available online. You have to calculate the weight on each wing. Does anyone have a list of the weights of each weapon?

You see the weight each weapon adds in the rearming window when rearming.

It is mentioned in NATOPS/Charts available online. You have to calculate the weight on each wing. Does anyone have a list of the weights of each weapon?

Weight alone is only part of the story; distance from the centre of the aircraft also influences the resulting moment.

Tested "double ugly" cat launches today, sans targetting pod of course. You really need to dial in the correct amount of aileron trim to keep straight on launch. Any sort of guide or rule of thumb on this? Was around 24 - 36 on FCS page for aileron trim difference.

 

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I always thought assymetric loads had to be trimmed out prior to cat launches. Interestingly, I've already heard from two hornet pilots that only longitudinal trim is set prior to takeoff. You deal with the roll assimetry yourself once airborne

I always thought assymetric loads had to be trimmed out prior to cat launches. Interestingly, I've already heard from two hornet pilots that only longitudinal trim is set prior to takeoff. You deal with the roll assimetry yourself once airborne

Depends on how much asymmetry, according to NATOPS. If there's only a limited amount, you need not bother. Above this, prior trimming required.

Depends on how much asymmetry, according to NATOPS. If there's only a limited amount, you need not bother. Above this, prior trimming required.

I see. Thanks for the clarification. I'm guessing they never had to deal with a real-life situation with enough assimetry to require trimming prior to launch, and assumed it was simply not used. I will bring this up with them and see what the response is. Good to know Natops has us covered yet again.

Depends on how much asymmetry, according to NATOPS. If there's only a limited amount, you need not bother. Above this, prior trimming required.

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Then I'd say DCS' flight model probably needs to be looked at. If that were the case in real life the real drivers wouldn't casually dismiss this question the way they did when it was raised (by saying they never did it and never saw it being done).

All in all, whether it behaves like the real thing in that specific scenario is irrelevant imho. If I ever find myself launching with assymetric loads I'll just trim the thing and have a safe launch. Thanks for the heads-up.

Edited for typos.

Then I'd say DCS' flight model probably needs to be looked at. If that were the case in real life the real drivers wouldn't casually dismiss this question the way they did when it was raised (by saying they never did it and never saw it being done).

 

All in all, whether it behaves like the real thing in that specific scenario is irrelevant imho. If I ever find myself launching with assymetric loads I'll just trim the thing and have a safe launch. Thanks for the heads-up.

 

Edited for typos.

Well, no. You need 11,000ft.lbs of asymmetry before you need lateral trim, so it's quite possible the reason the RW pilots never saw it is because they were never mad enough to load all their stores on one wing!

What's exact payload by pylons for double ugly?

1 - aim 9x

2 - gbu-12

3 - gbu-12

4 - aim 120c (in place of tgp)

5 - fuel tank

6 - aim 120c

7 - fuel tank

8 - gbu-12

9 - aim 9x

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Pretty much any double ugly configuration is any payload that involves a fuel tank on the centerline, and another one on the inner pylon on the starboard wing (always starboard to not obstruct the TGP's field of view on the portside).

Has anyone figured out an easy way to trim for this in DCS? Whenever I've tried it, my trim settings are only good for a 5kt window, and when you're accelerating on takeoff that 5kt window comes and goes very rapidly.

Hope this helps guys. This can be found in the:

F/A-18A-D Hornet PCL (Pocket Check List) NATOPS

A1-F18AC-NFM-500 p.28

You need to know your weapon weights and apply the chart accordingly. I use it quite often.

So we should be trimming stabs not ailerons then?

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your trimming your ailerons and as such cannot be done until wings down or on the cats

Hope this helps guys. This can be found in the:

F/A-18A-D Hornet PCL (Pocket Check List) NATOPS

A1-F18AC-NFM-500 p.28

You need to know your weapon weights and apply the chart accordingly. I use it quite often.

That's in foot-pounds, i.e. pressure (if I'm not mistaken). We have no way to calculate the foot-pounds from the weapon weight we get in DCS without additional information on stores position.

your trimming your ailerons and as such cannot be done until wings down or on the cats

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As dumb as it sounds it works, up too you whether you wanna try it or not. Here is a link to my previous PCL uploads, weapon weights are in there and is what I use.

https://forums.eagle.ru/showthread.php?t=218035&page=2

As dumb as it sounds it works, up too you whether you wanna try it or not. Here is a link to my previous PCL uploads, weapon weights are in there and is what I use.

 

https://forums.eagle.ru/showthread.php?t=218035&page=2

That chart also looks useful! I didn't see the moment foot-pounds conversion in NATOPS.