Takeoff Trim seems too Nose Up!

[CommandT]

Hey folks, so I've been learning the Hornet and am fairly sure at this point I am not doing anything wrong. I see that pressing the takeff trim button sets Nose Up trim to 12 unis. Taking off from land airfield you are supposed to go up to 16/17 or 19. But even with 12 the nose of the plane basically rotates passing 100kts. I end up trimming down straight away to prevent it rotating into a vertical climb... something is off... any ideas? (using half flap setting for take off)

[randomTOTEN]

can you post a short track?

[Svsmokey]

Actually i think the higher numbers are for higher weights off a carrier . Are you starting cold ? You'll want to press your FCS reset and takeoff trim buttons before takeoff . Bit page should show 12 on horiz stabs and 30 on verticals .The nose does rotate on it's own , but you won't break ground until 150-ish depending on load . I often fly with full internal fuel , 2 mk82's 2 sidewinders , a couple of amramms , a targeting pod and 4 mavs , and the aircraft flies itself off nicely . Flaps up at +100 feet and gear up before 250 knots . You should NOT have to touch the pitch trim until landing .

[Swift.]

12 for Field, 16/17/19 for Boat depending on weight.

 

12 on land will make you rotate at ~140ish depending on weight, as soon as you have a positive rate of climb then gear up. Control any climbing by using the stick, that's what its for.

[Harker]

Exactly what @Swiftwin9s says. From an airfield, as s soon as you have positive climb rate, gear up, and then flaps up. From the carrier, gear up as soon as you launch, flaps up as soon as you have positive climb rate.

[CommandT]

Well what I'm doing seems correct. I'm just saying the plane rotates itself off the ground after passing 100-130kts without touching the stick. That's with using 12 units. If I go up to 16/17/19 it's even worse. I don't beleve the real plane rotates itself. You'd have to pull on the stick. Something isn't right here.

[AvgWhiteGuy]

You may not be clear on what they're saying; it's ALL dependent on aircraft weight. I've never taken off at an airfield with a 16/17/19. Now having said that, there has been an issue of excessive nose-up in the past but I've found (as mentioned above) to make sure to reset FCS, takeoff trim, and flaps (several times) and the problem has not occurred.

If this doesn't work, as mentioned above, can you post a short track.

[Harker]

Well what I'm doing seems correct. I'm just saying the plane rotates itself off the ground after passing 100-130kts without touching the stick. That's with using 12 units. If I go up to 16/17/19 it's even worse. I don't beleve the real plane rotates itself. You'd have to pull on the stick. Something isn't right here.

The real plane rotates itself. You don't have to pull the stick, because there's already a 12 degree trim in place. It's very rare that I need to pull the stick for a runway takeoff and that's when I was very heavy. And again, the 16/17/19 are only for carrier takeoffs.

[kengou]

With a light load i find it auto rotates. With heavier ordnance load outs I pull the stick back myself at the appropriate speed.

[Eldur]

Actually i think the higher numbers are for higher weights off a carrier .

 

Those are, but even at 12° the thing skyrockets like an EEL on steroids if we don't push the stick halfway forward until the flaps are up. Has been totally different in the beginning of EA and changed sometime in around the Tomcat release I reckon.

[Svsmokey]

Dunno , i don't leave the flaps down . I clean up the aircraft a second or so after t/o , primarily to prevent overspeeding with the gear down .

[Eldur]

I raise them as soon as I have a +ROC, with the gear at once. But it takes ages to pull them in and while they're doing that, pushing to keep the nose from going up is mandatory... and I don't even take off with cans lit

[Svsmokey]

Weird . I'm hands free on the initial climb arming , a/g buttoning , cooling ir maves & flir-ing while turning to course and climbing to cruise altitude (usually 4k or so) .

It may be time to do some snakeye practice & stay very low after takeoff to see if what you describe is problematic for me .

[maxTRX]

Weird . I'm hands free on the initial climb arming , a/g buttoning , cooling ir maves & flir-ing while turning to course and climbing to cruise altitude (usually 4k or so) .

It may be time to do some snakeye practice & stay very low after takeoff to see if what you describe is problematic for me .

 

When it comes to normal runway T/O with half flaps, 12' trim, at just about any weight, the Hornet's behavior seems to be fine. Once the jet is off the runway the pitch stabilizes somewhere around 12, 13 deg. The gear comes up and even if you leave the flaps down the jet accelerate quickly past 240 knots and transition to UA seems to be fairly smooth. Flaps switch up and amber disappears, np there. No issues coming off the boat either, with higher trims.

The problem starts with transition to PA. Also, once trimmed to on-speed and you bolter (wheels hitting the deck) or do touch & go, the 'on-speed' stays the same.

Edited May 1, 2020 by Gripes323
wtf is going on with my keyboard!? USB or...? ;)

[Notso]

Hey folks, so I've been learning the Hornet and am fairly sure at this point I am not doing anything wrong. I see that pressing the takeff trim button sets Nose Up trim to 12 unis. Taking off from land airfield you are supposed to go up to 16/17 or 19. But even with 12 the nose of the plane basically rotates passing 100kts. I end up trimming down straight away to prevent it rotating into a vertical climb... something is off... any ideas? (using half flap setting for take off)

 

Had this same thing happen also just this week taking off from Nellis (takeoff from runway hot). AFAIK, I never selected T/O trim as I never needed to in previous field takeoffs. However, this time it pitched up violently and I had to hold almost full stick FWD and hold the trim button full forward to keep it level even with gear & flaps up. Even then, full fwd trim would never take it out. If I released the stick, it would pitch up suddenly again. I finally had to just end and restart the mission as it was uncontrollable to fly. The takeoff after resetting was uneventful and it handled normally. I guess it was just a "queertron" in the system.

[maxTRX]

Had this same thing happen also just this week taking off from Nellis (takeoff from runway hot). AFAIK, I never selected T/O trim as I never needed to in previous field takeoffs. However, this time it pitched up violently and I had to hold almost full stick FWD and hold the trim button full forward to keep it level even with gear & flaps up. Even then, full fwd trim would never take it out. If I released the stick, it would pitch up suddenly again. I finally had to just end and restart the mission as it was uncontrollable to fly. The takeoff after resetting was uneventful and it handled normally. I guess it was just a "queertron" in the system.

 

Did you have a chance to peek at the FCS page? Was it trim acting up or pitch axis?

[Notso]

Did you have a chance to peek at the FCS page? Was it trim acting up or pitch axis?

 

No, I didn't even think to look there. I just ended the mission and started over. I will look next time. Thanks.

[dmkellerman]

The only times I've experienced uncontrolled pitch up on take-off has been when I've forgotten to lower flaps. Is it possible your flaps are up on take-off?

[Sickdog]

At the risk of getting into an aerodynamic debate, I feel the real issue is the retraction of flaps from Half to Auto during a field Takeoff. I find that the nose pitches up quite drastically regardless of the aircraft weight when the flaps are retracted. It's hard to get a nice smooth climb-out like I've seen in videos when cleaning up. And yes, I am a civilian jet pilot in real life, and no I don't have any time in a real Hornet or any other military jet, so perhaps this is realistic and I'm using poor technique... but I don't think so.

[CommandT]

Any aircraft, properly trimmed, should begin to rotate upon achieving the necessary speed to do so - including the Hornet.

 

Set the trim to 0 and look at the horizontal stabilizers in F2 view. Then trim it with the takeoff trim button. If you don’t think with that deflection that the jet isn’t or shouldn’t rotate with enough airspeed I just don’t know what to tell you.

 

That said when I’m loaded close to MGTOW and 12 units I do have to snatch that pig off the deck with stick - and you better because you’re gonna hear the bang of blown tires if you’re doing 180 or more and still on the ground.

 

Well as someone who flys aeroplanes for a living with 4000h of actual real aeroplane flight time with most of that on jets, I can assure you no aircraft that I have ever flown in real life has rotated itself. That's madness.

 

I'd be amazed if the Hornet is supposed to rotate itself off a runway. On a carrier - ok, different story. But off a runway nobody should be expected to have to apply lots of nose-down stick and trim to keep it pitching into a vertical climb. Something is wrong. Maybe it's my specific system, I don't know.

 

Also I'd like to point out that in Wags's offcial tutorial video from a couple of years ago on taking off in the F-18 he makes a remark that you have to pull back quite a lot on the stick to rotate the plane... I think we can all agree from the comments here this is not the case for anyone any more...

 

And yes, I reset FCS, flaps half, set takeoff trim - it goes to 12 units. According to the manual I have to increase that further to 16/17 or 19 when taking off on an airfield depending on weight. But even at 12 units it's ridicullous. I set it to 6 and it seemed way better!

 

P.S. Making a video would be pointless unless I could also film my physical control inputs.

[randomTOTEN]

P.S. Making a video would be pointless unless I could also film my physical control inputs.

That's exactly why the first (my) reply was asking for a track. We can display the control indicator and see exactly what control inputs DCS is detecting. We can take control of the view and see things that you have not shown us with a video. We can take direct control of the simulation at any point to experience the phenomenon ourselves. We can replay it within our simulations to see if it's an error unique to your installation, as many times as we need. The developers can active their debugging interfaces and see what's going on internally in the program/simulation/module.

It's a single file automatically made by DCS, very small, and can be uploaded on this forum if it's short enough.

 

I don't understand why we're on page 3 and you still haven't uploaded it.:huh:

[CommandT]

That's exactly why the first (my) reply was asking for a track. We can display the control indicator and see exactly what control inputs DCS is detecting. We can take control of the view and see things that you have not shown us with a video. We can take direct control of the simulation at any point to experience the phenomenon ourselves. We can replay it within our simulations to see if it's an error unique to your installation, as many times as we need. The developers can active their debugging interfaces and see what's going on internally in the program/simulation/module.

It's a single file automatically made by DCS, very small, and can be uploaded on this forum if it's short enough.

 

I don't understand why we're on page 3 and you still haven't uploaded it.:huh:

Ahh! My apologies! Still learning this damn sim haha. I see what yu mean. Once I'm done sorting out some grahics settings I'll make a track file and upload it. Can I attach it to the post somehow or have ot put it up in the cloud with a link to download?

[randomTOTEN]

no worries!

On this "Quick Reply" box, click the "Go Advanced" button... then under the "Additional Options" section, select the "Manage Attachments" button.

 

Tracks work better when they're shorter rather than long (also keeps the file small). I like to replay it myself to make sure it saved correctly before uploading.

[Razor18]

Well as someone who flys aeroplanes for a living with 4000h of actual real aeroplane flight time with most of that on jets, I can assure you no aircraft that I have ever flown in real life has rotated itself. That's madness.

 

I'd be amazed if the Hornet is supposed to rotate itself off a runway. On a carrier - ok, different story. But off a runway nobody should be expected to have to apply lots of nose-down stick and trim to keep it pitching into a vertical climb. Something is wrong. Maybe it's my specific system, I don't know.

 

Also I'd like to point out that in Wags's offcial tutorial video from a couple of years ago on taking off in the F-18 he makes a remark that you have to pull back quite a lot on the stick to rotate the plane... I think we can all agree from the comments here this is not the case for anyone any more...

 

And yes, I reset FCS, flaps half, set takeoff trim - it goes to 12 units. According to the manual I have to increase that further to 16/17 or 19 when taking off on an airfield depending on weight. But even at 12 units it's ridicullous. I set it to 6 and it seemed way better!

 

P.S. Making a video would be pointless unless I could also film my physical control inputs.

 

 

If you can comprehend why the Hornet rotates and pitches up on a carrier take off, why would the same airplane do the same procedure otherwise on a land based take off? Only the speed increase from zero to rotation speed and above, is much quicker on a cat shot. If you would trim your RL aircraft so "nose high", they would do the same rotation, expect that would be much slower rotation, and more unsafe without the excess power the Hornet has. But if you would take off with a "Nose high" trim setting, that gives you level flight just let's say 10 kts above your stall sped, then it would definitely rotate by itself soon after you would exceed that "stall + 10 kts".

 

In the Hornet (and I'm quite convinced in any aircraft), with the trim you actually set AoA. After that, if you push the throttle, you will climb even if you do not touch the stick for pitch, and if you pull back throttle, you will sink. The more excess speed, the higher the nose, and likewise. The aircraft want to have that AoA back. There will be one speed only, where you will fly level. The Hornet does the same, it is just the extreme acceleration, that exagerates the whole process to a level more difficult to manage.

 

Try taking off with take off trim set but no afterburner, and even reduce that when you get close to rotation speed, to transition through it slowly. Not the speed at rotation. After positive rate, do not clean up, don't use the stick for just reduce throttle just enough to return to level flight. Speed will be somwhere around rotation speed, or a bit below. Note also, how small speed increase is enough for the VV to already start going higher.

[pete_auau]

Well what I'm doing seems correct. I'm just saying the plane rotates itself off the ground after passing 100-130kts without touching the stick. That's with using 12 units. If I go up to 16/17/19 it's even worse. I don't beleve the real plane rotates itself. You'd have to pull on the stick. Something isn't right here.

 

 

Actually if you have watched the "mover" series on utube he states on take off runways you dont have to touch the stick as the aircraft will take off automatically if the aircraft is trimmed correctly