P-51D Military and Civilian Takeoff Issue

[ockwellk]

Yea, these are my findings as well. Which is why I had so much difficulty in V4. It still rolls to the left on the runway but pushing a little forward before takeoff gets me in the air. Once stable at 1,000ft all ok???

[Japo32]

Same problem. Just takeoff it goes to the left and sink. I have 260 hours in the P51 and never saw something like this before.
You can see the moment of takeoff in this video:

https://youtu.be/Zar7fmHkQ5Q?t=1695

I had some issues with vatsim vpilot in P3dv3 when using the FSX version in it.. so I thought it was that and deactivated, but later I just connected again and the plane flought all the trip without any issue of VPilot.

[DHenriques_]

Same problem. Just takeoff it goes to the left and sink. I have 260 hours in the P51 and never saw something like this before.
You can see the moment of takeoff in this video:

https://youtu.be/Zar7fmHkQ5Q?t=1695

I had some issues with vatsim vpilot in P3dv3 when using the FSX version in it.. so I thought it was that and deactivated, but later I just connected again and the plane flought all the trip without any issue of VPilot.

The Mustang in the video is being rotated WAY too early! Airspeed is too low and power is reduced. Not good in this airplane. Pilots have to forget what works in a light GA type plane when flying the Mustang. Read the manual carefully on the numbers required to get this plane off the ground safely and in one piece. LOL
Dudley Henriques

[Japo32]

As said.. I have flought the plane for 260 hours, and I didn't pull the joystick. It was lifting itself not me. Then in the air, the same problem banking to the left was happening even with good speed, until I raised the landing gears.
I never had that problem before.

Edit: made a second flight today and all seems ok.. But this time I closed the canopy. I toke the first time with the canopy open to simulate as pilots did when taking off in case of emergency to jump. Maybe the canopy was the culprit of the strange issue? Don't know.

[Jacques]

I don’t think that Dudley is wrong in that the aircraft clearly rotated too early. I tried to see your elevator trim settings in the video...and they looked fine. But I have had strange things happen in flightsim before so I wonder if some inadvertent key press, or even a stuck key or controller command caused the elevator trim to roll to the stops in the “up” position.


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[AviationAtWar]

Having the flaps partially extended didn't help anything.

[WB_FlashOver]

I did some testing tonight and recorded a little video. It has been quite some time sense I have been in the Mustang, in FSX, so I am a little rusty. I know there are some areas that I need to practice and improve on. Anyhow, the manual says keep stick back until enough airspeed is achieved for rudder control. The first segment is with 6 degrees right rudder trim, full right rudder, 50% right brake. By the time the airspeed indicator is showing a reading, the time I would normally lift the tail, I have rotated a good 60 degrees to the left on the airfield.

The second segment is lifting the tail almost immediately but the airplane is still rotating hard left before the tail rises and rudder control is achieved.

Even taxiing is very difficult with or without unlocking tail wheel. Right brake is needed almost the whole time that the tail wheel is on the ground. I may be doing it all wrong but it seems to me the rudder has zero effect while tail wheel is on the ground, locked or not.

Cheers
Roger

[CodyValkyrie]

Guys, I did some testing on both the military and the civilian 'Stangs at different weights, and with/without canopy open. Sadly, I cannot confirm what you guys are seeing.

Watching Flashover's video, I did notice something that caught me by surprise, which perhaps some of you guys are having issues with.

DON'T CHASE THE PLANE'S NOSE!

Be ahead of your aircraft. Watching Flashover's video, I noticed your rudder inputs were happening when the aircraft had already committed to essentially a ground loop.

I'd also like to point out that the rudder trim will serve little for the takeoff run. This is ONLY to compensate during the climb. Once you're in cruise, you adjust as desired. This just compensates a bit so that during the climb, you're not fighting the aircraft, and won't help terribly much during takeoff, where you need to FLY the aircraft.

Here's how I've been doing my takeoffs:
1) Stick back, or aft of center.
2) Apply power gradually, but firmly. (Removed initial length, see post below.)
3) AS power is applied, I begin to compensate before the nose starts moving much. Generally, I begin with little to no rudder input as I increase throttle, but by the end of my throttle movement I have my rudder in. I apply it BEFORE the nose veers off to the left, and then only compensate gently as I watch the nose for small movements to keep on centerline.
4) At around 40 indicated I already have the stick centered.
5) I keep the stick centered, and my rudder input in as necessary until takeoff speed is achieved. I generally pull her off the deck around 120MPH indicated.
6) Prior to liftoff, I generally add a touch of right aileron, expecting the left wing to drop. This is a well known and documented issue with the Mustang, especially at low speeds. I don't add much, but a touch, and that generally keeps the wings level. I lower the deflection smoothly as the plane stabilizes.

Now, breaking down what I think some of you may be doing:
1) I think some of you guys may expect your trim to negate the torque. It won't.
2) You're waiting for the nose to drift before adding rudder. Add rudder, then watch the nose, and adjust. You're getting yourself behind the torque otherwise, and you'll never recover. Abort, and try again.
3) Don't yank her off the ground too early, or that left wing will drop fast and hard. A lot of pilots have died from this during landings, and takeoffs. The plane should almost fly itself off the ground in a tail low takeoff with minimal input to get off the ground.
4) WEIGHT makes a difference. If you have that aft fuel tank loaded, give her a bit more speed, and be careful on lifting off. Add 10MPH or more, and don't yank her up as she's going to be very tail heavy already, and will try to kill you.

[WB_FlashOver]

DON'T CHASE THE PLANE'S NOSE!

Be ahead of your aircraft. Watching Flashover's video, I noticed your rudder inputs were happening when the aircraft had already committed to essentially a ground loop.

Good catch Cody. I knew someone would see that. I find there is a sharp pull to the right with first throttle, then a short straight run, then she starts pulling left. It is challenging to know when to start the correction. This is compounded by my twist stick having a loose connection between handle and shaft which makes you think you are adding rudder, more rudder, and then it pops over, at which time I have gotten behind in my controls. Again, good catch.

Ok, all excuses aside let's do a comparison between FSX-SE and P3Dv4. I have nearly 500 hours in the 51 in FSX and I knew I was not that out of practice so it was good to fly her in FSX again for my own satisfaction. It still feels like there is no rudder control until you raise the tail wheel. FSX has enough rudder control to keep her straight even with tail wheel down but you are still dancing on the peddles as you should be. You will notice that I did not raise tail wheel with elevator in FSX until nearly 55 knots. In P3D I was off runway by the time I reached 55 knots.

So I guess my question. Is the P3D version more accurate than the FSX version? If it is I can deal with it and just raise tail wheel as soon as I have elevator control. I like the challenge but as said by another, "she seems out of sorts". Do I need to re-download and try another install? Should I remove my plane data file and start with zero hours? Or am I just doing it wrong?

Thanks and Cheers
Roger

[CodyValkyrie]

I'd defer to Lewis on that, but it can't hurt to uninstall (everything) and reinstall. I don't have FSX installed anymore, but I haven't noticed any discernible differences offhand.

My nose doesn't move too much to the right, and if it does I give it a small movement to the left, but I don't linger on it any, because I'll not notice the movement to the left if I do. Often, I just let it swing a little bit to the right, and let the nose come center as I've already adjusted for the left turning tendency. Honestly, perhaps I should make a video or something, because I don't "think" much about what I'm doing in this process. I've mostly done it by memory, and feel.

I've seen pilots do full wheel takeoffs in real life, but I stand by Dudley's technique and generally take off tail low, like I would in the B-17, T-6, or most of the warbirds. No matter where that tail is, she'll be directly in the prop wash, and the rudder will be effective.

Let me see about making a small video.

[guillaume78150]

I find there is a sharp pull to the right with first throttle, then a short straight run, then she starts pulling left. It is challenging to know when to start the correction. This is compounded by my twist stick having a loose connection between handle and shaft which makes you think you are adding rudder, more rudder, and then it pops over, at which time I have gotten behind in my controls. Again, good catch.
Roger

Indeed, when applying power, the aircraft start to pull right, but I don't correct it as the propeller torque quickly put the aircraft back in line. That's exactly when I start to pull on the right pedal to keep it on a straight line, but slightly. When reaching 70/90 mph, applying some right aileron helps to keep her straight. Don't try to take off before getting enough speed. I use to let the P51 running on the runway tail high, it gains a bit more speed and takes off on her own.
I found applying power too slowly makes the aircraft difficult to keep in a straight line until she reach 80/100 mph. Applying it too quickly, well, everybody knows…
It's a matter of practice and I spent hours to take off and land on the same runway before managing to handle the aircraft in an acceptable way. But it's still far from perfection.
A2A should release a PT17, with the T6, this would make the perfect transition before flying a warbird…

[CodyValkyrie]

Okay, I need to amend a few things after filming this:
1 - I reach full power anywhere between 13-14 seconds (not 4, like I said above. I think I pulled that out of my a$$). How quickly I throttle up depends on what the nose is doing, and how much rudder I'm playing with. Dancing on the rudder should coincide with what you're doing on that throttle. You'll notice my application of power to near 30 inches is fairly quick, but I slow down quite a bit to get up to maximum takeoff manifold pressure, mostly because I'm balancing that with rudder input.
2 - Sometimes, I stop around 30MP, check everything, and continue throttling up.
3 - I do indeed bring the tail up just a bit, but just enough to remain tail low.
4 - The aircraft generally lifts off on its own in a tail low configuration.
5 - The position of the stick isn't terribly important to me during the initial application of power, but putting it back is recommended. The biggest thing for me is making sure you have a bit of right aileron, and slight pressure down to keep tail low at speed. If you leave the stick neutral, the plane may try to become airborne before she's truly ready, and you'll be in a world of hurt.
6 - Remember, trim recommendations are designed for climb power, not to assist in takeoff! I cannot stress this enough.
7 - You can wheel her down the runway longer if you desire. I'll leave it to Dudley to describe this technique best, but my guess it just a bit more down pressure. The plane will naturally nose down a bit with speed, and I keep a touch nose down on the stick so she doesn't come off the ground too fast.
8 - In both videos I'm using maximum takeoff power. 55 inches for the civilian with 100 octane, and 61 for the military with 130 octane.
9 - Notice I'm dancing on the rudders pretty fast, and I'm doing my best to stay ahead of the aircraft.
10 - The civilian mustang came off the ground around 87 knots (~100MPH), while the military came off the ground about 95 knots (~110MPH) in this video. Perhaps a tad early. Weight is the biggest factor.
11 - Notice the left wing dip? Again, apply right aileron to counteract before lifting off. I could have added a bit more aileron to counteract this, but you can see I did add some.
12 - Again, anticipate the torque, and swing. Stay ahead of the aircraft. You'll notice I often apply right rudder before I need it, then dance on the edge of it to align myself.
13 - After takeoff, you'll see me raise my gear and do my power reduction. I'm slipping a bit in both videos (I think I forgot rudder trim in the military variant), but you get the general idea.
14 - Lastly, things happen fast. This is where experience and feel come into play. I never really broke down how I takeoff until now, but keep in mind I've been flying the Mustang since beta many years ago. At this point I focus pretty heavily on my scan, the slightest movements of the nose, MP, etc. It all happens so damn fast, which is one reason I sometimes hold at 30 inches and do a quick scan. Keep in mind I also never takeoff in this view, as I use a TrackIR. I quick flick around to check things during the takeoff run.

I don't really feel like this is much different then how I flew her in FSX. I don't recall any growing pains going to P3D. So, it's possible that once you're behind the torque it might be more pronounced in P3D, but I think if you can keep on top of it, it should be basically the same.

Note that these are just my techniques. I'm no expert. Also, please forgive some of my techniques, and the fact I wrote "civilian" on the second takeoff. I've been hammered on drugs for the last week dealing with strep throat. Thankfully, I'm getting better, but half the time I don't even know what's going on around me. I'll probably look at this in a week and shake my head in disgrace.

Here’s the link for those of you on a mobile device:
https://youtu.be/1oL4LwU74pQ

[taildraggin68]

Great videos Cody. My take off routine is very similar and I have overcome those issues in v4. My concern is in the elevator trim. I absolutely do not expect to be able to hands free this plane, but at a constant power setting, with no change in airspeed or attitude, she will enter a 1000 to 1500 ft dive without warning if looking away for more than a second or two. Now, I am not sure if something is conflicting, and have not nailed down any potential culprits yet, it's more of a feeling that things are a bit more sensitive in v4. It is like what you could get away with in FSX will bite you quick in v4.

More of just a feel, sort of like the rigging test Scott put out with the Cherokee that a few of us managed to get.

Keeps you on your toes.

[Killratio]

A lot of these problems come from a fundamental misunderstanding of HOW a rudder works. It needs AIRFLOW. Have a look at THIS video which is of an early Spitfire with MUCH less adverse torque effect than a P-51.

https://youtu.be/0bMrhLG3tM4?t=38s

Even a docile Tiger Moth requires a HEAP of rudder AND a burst of power to give ANY rudder effect at taxi speeds.

I always find it funny that sim pilots and tricycle pilots, even real ones, have trouble with these birds in FSX/ P3D. A Tricycle undercarriage leaves the rudder FULLY in the airflow from day one. Not only that but in your average tricycle, the nose wheel is working for you as well.

Real tailwheel qualified pilots have less problems, warbird pilots less still. I can honestly say that even in Beta, the p-51 never got away from me on takeoff. But then again, I KNEW to treat it with respect. Having nearly ground looped a Tiger Moth IRL, I suppose a certain "respect" is burnt in (and THAT was on landing, power off!). Having taxiied a Tiger with ONLY rudder and no brakes, you learn to put the rudder on an apply power about 3 days before you expect it to turn. Sim pilots often interpret this as "my rudder isn't working"

Guess what.. It isn't!

So I'll go "He" if Dudley has ever put the A2A P-51 sideways after it was adjusted to "proper handling".

Yeah, I'm not a very touchy feely, sympathetic guy... deal with it


(and hey, Cody has broken more aeroplanes than Boneyard .... and he can do it! Sorry Codes )

[Killratio]

with no change in airspeed or attitude, she will enter a 1000 to 1500 ft dive without warning if looking away for more than a second or two.

taildraggin68... Even your average Cessna 172 will do this IRL under certain circumstances.(ask the trainee pilot, who shall remain nameless, who bent down to pick up a dropped pen on takeoff!)