Takeoff Trim seems too Nose Up!

[Cab]

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!

 

Can you confirm where you see this in the manual? The only place I can find a reference to those trim settings is page 96, and that section is about carrier ops.

[Razor18]

Just found this takeoff video showing the stick first, where there seems to be not much pushing (if at all) after lifting off, then you can see the stabilator working. The stab goes apparently full "nose up" at the end of the cat stroke, obviously to reach trimmed AoA ASAP, but then as soon as "Weight off Wheels", they snap back to "normal climbing", with not too much visible nose up tendency.

 

 

And interestingly, the stabilator movement in DCS is totally mimicking RL behaviour, if you watch your own plane from the outside.

Edited May 2, 2020 by Razor18

[Oscarn]

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.

 

Gear and flaps up as soon as you have a positive rate of climb and the aircraft will trim itself, and as said before only use 12 degrees for airfield take offs, 16/17/19 are for carrier launches

[CommandT]

Sorry, my apologies aboit the 12 and 16/17/19 units. 12 is for shore takeoffs indeed.

 

If the real plane rotates itself off a runway in real life then fair enough. I just thought my trim or something was wrong as no other plane generally tends to rotate without any stick intervention.

[CommandT]

Just found this takeoff video showing the stick first, where there seems to be not much pushing (if at all) after lifting off, then you can see the stabilator working. The stab goes apparently full "nose up" at the end of the cat stroke, obviously to reach trimmed AoA ASAP, but then as soon as "Weight off Wheels", they snap back to "normal climbing", with not too much visible nose up tendency.

 

 

And interestingly, the stabilator movement in DCS is totally mimicking RL behaviour, if you watch your own plane from the outside.

 

I'm not sure if the FCS has some sort of carrier TO mode but you can see the horizontal stabilizers rotate almost fully nose-up right before the plane leaves the end of the deck when launching. I'd imagine the FCS will not automotically command full nose-up on a runway without you pulling back on the stick.

[Svsmokey]

I'm not sure if the FCS has some sort of carrier TO mode but you can see the horizontal stabilizers rotate almost fully nose-up right before the plane leaves the end of the deck when launching. I'd imagine the FCS will not automotically command full nose-up on a runway without you pulling back on the stick.

 

Hornet pilots launch from a carrier with hands on the glareshield , not on the stick , so it is all automatic .

Edited May 2, 2020 by Svsmokey

[CommandT]

Hornet pilots launch from a carrier with hands on the glareshield , not on the stick , so it is all automatic .

 

Yes I'm aware. I'm just saying I wonder if the FCS behaves differently when it launches off the carrier. In the video it deflects horizontal stabs fully nose up just as the plane gets to the end of the deck on launch... I'd imagine it does not do this when taking off from an airfield.

[Swift.]

Yes I'm aware. I'm just saying I wonder if the FCS behaves differently when it launches off the carrier. In the video it deflects horizontal stabs fully nose up just as the plane gets to the end of the deck on launch... I'd imagine it does not do this when taking off from an airfield.

 

Sounds like you are describing the FCS logic in a super hornet. Whereas legacy hornets will hold their stabs in position until off the end of the cat, superhornets will keep the stabs flat until near the end of the cat. This is because the superhornet has much larger stabs which would reduce the acceleration due to aerodynamic forces. The behaviour off the end of the cat is the same though, both will seek the correct AOA to ensure safe fly away.

 

Its this seeking of AOA that makes the hornet 'auto rotate'. As it goes along the runway the AOA is ~0 so the plane is constantly trying to increase that to the trimmed value, this means that as soon as the airspeed will allow a rotation the plane will do so to reach the trimmed AOA.

[G B]

Relying on knowledge of the Super Hornet to infer how things are in the Hornet can cause trouble. Many many little differences like this one exist.

[Razor18]

Just a little excerpt from F-18 features to come:

 

 

"Iterations during 2020 until completed:

Update flight model for ground effect, takeoff pitch effects..."

[FightsOn]

The A-D Hornets rotate themselves off the ground at nosewheel liftoff speed, the Rhinos (and Growler) need to be positively rotated with aft stick (ashore). It’s one of the differences between the two airframes they cover in transition training.

 

Both jets need a little push on the stick as the flaps come up ask the jet transitions to UA flight. It’s very little, but if you pay attention it’s definitely there.

[maxTRX]

Both jets need a little push on the stick as the flaps come up ask the jet transitions to UA flight. It’s very little, but if you pay attention it’s definitely there.

 

Then, if you pitch up for a steep climb out you still have to keep nudging the stick forward very slightly to stay on a steady climb angle/speed, otherwise the pitch CAS logic will chase 1g?