Over Rotating on Takeoff

[Super Wabbit]

At heavier weights, such as two Wing tanks, missiles, centerline bombs, I'm finding that the procedure to hold full aft stick at 80 knots results and over rotating and a tail strike for me. I also set trim to -3 instead of the -2 that it seems to start with on a hot start. Since the aircraft won't lift off like it does in a clean configuration when it rotates with aft stick applied, you sit there at nose high attitude for a bit before it wants to go flying.  Also worries I'm technically exceeding the tire speed rating. 

In other aircraft, I would simply release back pressure on the stick as the nose rotates but, the F4 does not seem to have a one-to-one ratio between my real world stick inputs to its virtual stick causing me to over correct.  It feels like the stick is extremely sensitive in the pitch axis as if there is a large curve on it (no curves are set). I think that's cuz they're replicating how the control surfaces work in the real world but it's really throwing me off. 

Bringing up the control indicator with the aircraft sitting on the ramp, you can see that the stick naturally rests full forward with a little bit of down pitch trim.  In this state, my real world joystick is centered. Pulling full aft on my stick from the centered position sees the virtual stick  go from full forward to full aft, which is why it feels overly sensitive.  

Does anyone have tips on not over rotating on takeoff with a heavy aircraft?  Is there a setting I'm missing, or a tip on when to actually rotate, say after 80 knots? If I wait to pull aft stick to 100 or 120kts I don't over rotate and the jet takes off quite well.  But is that the real world procedure?

[=475FG= Dawger]

I wouldn’t get wrapped up too much in real world procedure or not. 

Do what it takes to fly the airplane. 

When the nose comes up, forward stick is required. It is tough not to overcorrect because you have no real feel, just visual clues and in this case, visual is far too late.

Practice is the only remedy.

 

[Zabuzard]

Make sure you do not have the "Use FFB" option checked in your DCS settings. Some reported that it auto-enabled itself after the last update again, and it is known to cause issues like that.

And yes, the reason the stick becomes "so sensitive" and moves all the way aft during takeoff is due to the bellows starting to sense speed. So they start to pull the stick aft by themselves, taking away more and more of the force applied by the bobweights.

[Temetre]

I usually struggly a bit, because when I try to let off as soon as the nose gets up, I almost always overcorrect and the nose goes down right down to ground currently. Even when I try to be really soft. But yeh might be skill issue, and I dont think I damaged my plane yet (tho maybe the damage model is forgiving with tailstrikes, idk).

(checked that FFB is off!)

Edited July 15, 2024 by Temetre

[=475FG= Dawger]

10 minutes ago, Temetre said:

I usually struggly a bit, because when I try to let off as soon as the nose gets up, I almost always overcorrect and the nose goes down right down to ground currently. Even when I try to be really soft. But yeh might be skill issue, and I dont think I damaged my plane yet (tho maybe the damage model is forgiving with tailstrikes, idk).

(checked that FFB is off!)

 

A stick extension is helpful for fine control such as in this instance

[Super Wabbit]

Thanks everyone.  I did check and FFB was not enabled.  I'm running the Thurstmaster Warthog and at this stage in its life my stick isn't as smooth as it once was.  A stick extension would definitely help.  I mean, I'm not really upset that this means I need to spend more time practicing!

[Art-J]

Don't feel bad, I've got a 30 cm extension on my Warthog and suffer from exactly the same symptoms on takeoff. Just gonna have to practice and "git gud" at it eventually I guess (or buy the FFB stick at last ).

[Super Wabbit]

I just spent some time practicing and on the advice of another DCS friend I experimented with different trim settings.  

At a heavy loadout (say between 95% and 100% of gross weight), I found that setting trim to halfway between 0 and -1 works really well.  My new takeoff procedure for this trim setting is:

• Full aft stick before 80kts
  • There will be a slight nose up pitch as the nose gear fully extends, continue to hold full aft stick.  
• At the next nose up pitch moment, release the stick to neutral and the rotation is captured at roughly 10 degrees.  Make small pitch corrections as needed and the aircraft should fly-off momentarily.  
• Apply nose down trim and/or stick to maintain 10 degrees of pitch as the jet accelerates to 350.

Probably still needs a little more testing and practice but I'm not over rotating and on the replays, my takeoffs look very similar to videos of the real thing.  A look at the manual suggest -1 to -3 trim for takeoff.  It also notes that for light weight configurations may cause you to have an aft CG and to take note to not over rotate.  Given than, using less nose down trim for a heavy takeoff makes sense to me.

Trying -1 nose down trim works but isn't as error proof for me, but if you're stuck on flying by the book I think a little more practice and I can make that work.  I did also try a 0 trim setting and easily over rotated.  The nose just rotates way too fast and you need forward of center stick position (in the real world) to stop the over rotation.

[Holbeach]

Just to add.

T/O from Port Stanley with full AA kit.

I use default trim. Full aft stick at 80 kts, then ease it forward a bit, (not very technical I know) and hold it there.

Aircraft leaves the ground gently without tail strike.

..

[aaronwhite]

9 hours ago, Super Wabbit said:

Thanks everyone.  I did check and FFB was not enabled.  I'm running the Thurstmaster Warthog and at this stage in its life my stick isn't as smooth as it once was.  A stick extension would definitely help.  I mean, I'm not really upset that this means I need to spend more time practicing!

I'm flying the same stick (it's "crotch" mounted with my desk mount I use) and what I've been doing, which likely isn't very real world, but whatever, is to pull full after on the stick at the start. Just hold back all the way as I'm letting off the brakes. 

Then as the airspeed builds and I get around the rotation speed, I'll wait until the nose starts to pitch up and just ever so gently move the stick forward a bit, while still mostly holding back, to pull a little back, until my rear wheels lift off, and then I'll slowly lower it until whatever point gets me level flight to bring up the gear and flaps, then I'll pull back the throttles a bit for the climb and trim it out to hold that and take some pressure off. 

[Temetre]

Am 15.7.2024 um 13:52 schrieb =475FG= Dawger:

A stick extension is helpful for fine control such as in this instance

Aye but too expensive, would have to buy a new stick (and maybe seat) ^^

Running a VKB gladiator. Awesome, but cant take extensions really.

Am 17.7.2024 um 09:32 schrieb Super Wabbit:

A look at the manual suggest -1 to -3 trim for takeoff.  It also notes that for light weight configurations may cause you to have an aft CG and to take note to not over rotate.  Given than, using less nose down trim for a heavy takeoff makes sense to me.

Thats a very interesting point. I managed much better with clean takeoffs, but was using more trim for heavy loads, because it felt logical. So instead im now going to try less pitch trim then when im loaded.

I wonder if its realistic for the pitch of trim being so finnicky and dangerous tho, or more of a weirdness of flight and control model?

 

Edited July 18, 2024 by Temetre

[Kirk66]

Pitch trim is pretty much dead on compared to the real thing. Yes it was that finicky - you got used to it.

Remember that fuel and external loads all move the CG aft, making pitch more sensitive. Which is why it's so much easier to fly in the pattern with only 4k of fuel. 

Also, the nose down trim on takeoff is there to prevent a pitch up due to accelleration right after takeoff; 3 down means you dont really have to touch pitch trim until 350 knots or so. Pitch forces were (are) so light that it wasn't a struggle to hold off the nose down force as you takeoff and accellerate.

A stick extension is a big help. I use a 20 cm on a Virpil cm2, strongest springs (still way too weak), no curves. Works pretty good. I do adjust the roll deadband to 66% to make it roll faster since with the long stick it otherwise leads to too much lateral stick movement - feels like a P-51!

Vulture

[Super Wabbit]

On 7/22/2024 at 10:32 AM, Kirk66 said:

Remember that fuel and external loads all move the CG aft, making pitch more sensitive. Which is why it's so much easier to fly in the pattern with only 4k of fuel. 

Vulture

Realizing that made everything click into place.