Takeoff Demonstration FAIL (Video)

[benargee]

Hey so I just bought DCS: P-51D with the awesome sale and all. So being eager to learn how to get this beast airborne I went trough the tutorials in order untill I got to the Takeoff Demonstration and I wasnt fimiliar with this method of take off. Definitely different than how I

 

On a more serious note. WTF! I eventually learned how to take off without knowing whats normal. anyone else have this issue?

[Tango]

I was getting very upset at how it was behaving on the ground. I have never seen a tail dragger inexplicably start yawing to the point it can't be controlled during a takeoff roll at high power and at 60+ kts, even when using full rudder deflection at an early stage during recovery to straighten it out (it certainly hasn't developed to the point of uncontrollability).

 

I did find that it helps to ensure that the tail wheel is locked then to hold slight back pressure during the TO roll. Failure to do this (holding back pressure) results in the eventual *uncontrollable* yaw you see (and there appears to be an issue with how yaw is modelled in the FM in that regard).

 

By holding the tail down it seems the tail wheel helps prevent the yaw from beginning, and a normal takeoff ensues.

 

Regarding the yaw issue itself, the tail wheel should straighten up very quickly. Let's say you brake to the left, and stop the aircraft. The tail wheel is castored to the side. If opposite brake is applied, the aircraft should quickly yaw the opposite way, but in P-51 there is some kind of huge inertia that is preventing the aircraft from yawing as it should. One time it resulted in a ground loop from a standing start, with the opposite brake fully applied from the start of the maneuver.

 

Same situation occurs on landing, but it is more manageable there and doesn't seem out of the ordinary.

 

Takeoff however seems wrong.

 

Once the aircraft gets airborne things seem OK.

 

I have to say though - as frustrating as it was to start with, it is great fun to fly!!!! :D

 

See the track in this thread of the issues during start/taxi/takeoff: http://forums.eagle.ru/showpost.php?p=1704199&postcount=5

 

Best regards,

Tango.

Edited March 22, 2013 by Tango

[EvilBivol-1]

Hey so I just bought DCS: P-51D with the awesome sale and all. So being eager to learn how to get this beast airborne I went trough the tutorials in order untill I got to the Takeoff Demonstration and I wasnt fimiliar with this method of take off. Definitely different than how I

 

On a more serious note. WTF! I eventually learned how to take off without knowing whats normal. anyone else have this issue?

 

We've recorded a new takeoff demo track that should be included with the next patch. The current one was recorded some time ago and changes made in the flight model since are causing it to play back incorrectly.

 

I did find that it helps to ensure that the tail wheel is locked then to hold slight back pressure during the TO roll. Failure to do this (holding back pressure) results in the eventual *uncontrollable* yaw you see (and there appears to be an issue with how yaw is modelled in the FM in that regard).

Holding some back stick during the takeoff run to keep the tail wheel locked is standard practice on the Mustang, obivously until you're ready to get the tail up.

[Tango]

That's where my understanding of tail draggers and flight dynamics diverge. If I make an attempt (at say 100 kts) to get the tail up, an uncontrollable yaw is highly likely even if I jump on it very quickly.

 

I'm unable to "wheelbarrow" the aircraft down the runway and *gently* yaw it from one side of the runway to the other without it very quickly becoming uncontrollable in yaw in one direction or the other.

 

It results in going off the side of the runway and crashing.

 

Best regards,

Tango.

[Robo.]

That's where my understanding of tail draggers and flight dynamics diverge. If I make an attempt (at say 100 kts) to get the tail up, an uncontrollable yaw is highly likely even if I jump on it very quickly.

 

I'm unable to "wheelbarrow" the aircraft down the runway and *gently* yaw it from one side of the runway to the other without it very quickly becoming uncontrollable in yaw in one direction or the other.

 

It results in going off the side of the runway and crashing.

 

Best regards,

Tango.

 

Start with less power (40 or 45) and focus on the rudder work, if you know how the plane behaves it's easy to predict. You will be able to take off with bombs and rockets at full power with in a nice straight line with a bit of practice. That's what makes the fun here :pilotfly:

[Tango]

That's what makes the fun here

Indeed!! I knew it was not going to be easy, but not this hard either. :D

 

Best regards,

Tango.

[EvilBivol-1]

That's where my understanding of tail draggers and flight dynamics diverge. If I make an attempt (at say 100 kts) to get the tail up, an uncontrollable yaw is highly likely even if I jump on it very quickly.

 

I'm unable to "wheelbarrow" the aircraft down the runway and *gently* yaw it from one side of the runway to the other without it very quickly becoming uncontrollable in yaw in one direction or the other.

 

It results in going off the side of the runway and crashing.

 

Best regards,

Tango.

I understand what you mean and I'm sure most people, myself and our testers included, can relate to this in their initial experience of the Mustang. Give it a chance - give yourself a chance to feel out the controls, try one curve setting or another. As I'm sure you can see on the forum, after some practice it is actually very controllable on the ground and in the air.

[Tango]

Good point - I think I have straight curves for the rudder at the moment. I'll try adding some.

 

Best regards,

Tango.

[EvilBivol-1]

Yes, would definitely recommend a healthy 20+ curve on the rudder as you rarely need anything near full deflection anyway (so not overly concerned with high amplitude inputs far from center) and are mostly interested in having smooth input around the center.

[Suchacz]

...my 0,02$

 

Unzoom to the max during TO, it helps (me) a lot. With wider FOV you can better anticipate the tendency of the airplane to yaw or roll :thumbup:

Edited March 22, 2013 by Suchacz

[benargee]

We've recorded a new takeoff demo track that should be included with the next patch. The current one was recorded some time ago and changes made in the flight model since are causing it to play back incorrectly.

 

Yup that was my theory, i still find it funny though with the serious tone of the other tutorials, then BAM upside down burning wreckage... now you try. Its like saying this thing is so hard to takeoff in, we cant even do it...lul

[sobek]

Regarding the yaw issue itself, the tail wheel should straighten up very quickly. Let's say you brake to the left, and stop the aircraft. The tail wheel is castored to the side. If opposite brake is applied, the aircraft should quickly yaw the opposite way, but in P-51 there is some kind of huge inertia that is preventing the aircraft from yawing as it should. One time it resulted in a ground loop from a standing start, with the opposite brake fully applied from the start of the maneuver.

 

The CG is aft of the main wheels, which makes the whole assembly naturally unstable in the horizontal plane, the CG being aft adding positive feedback to a turn and at some point the inertia overcomes the wheel forces. This is nothing out of the ordinary. Basically what this boils down to is that you have a tight margin that you need to keep the plane in by acting as a control system or you will quickly find yourself in a runaway condition.

Edited March 22, 2013 by sobek

[pii]

Hey so I just bought DCS: P-51D with the awesome sale and all. So being eager to learn how to get this beast airborne I went trough the tutorials in order untill I got to the Takeoff Demonstration and I wasnt fimiliar with this method of take off. Definitely different than how I take off in the Warthog

 

Judge for yourself

 

 

On a more serious note. WTF! I eventually learned how to take off without knowing whats normal. anyone else have this issue?

 

LOL Yeah I went to watch the take off demo only to see it crash and burn just like I had done minutes earlier. WTF ? LOL

Looks more like a DEMO of what not to do.

[Merlin-27]

You'll be amazed how easy it becomes after some practice. Welcome to the club.

[gavagai]

Watched your video. Skip the step where you trim the rudder, or only trim a tiny bit.

[Flamin_Squirrel]

The CG is aft of the main wheels, which makes the whole assembly naturally unstable in the horizontal plane, the CG being aft adding positive feedback to a turn and at some point the inertia overcomes the wheel forces. This is nothing out of the ordinary. Basically what this boils down to is that you have a tight margin that you need to keep the plane in by acting as a control system or you will quickly find yourself in a runaway condition.

 

This is true. However, the biggest problem this creates isn't that there isn't enough rudder authority, it's that you have to be careful when to use it; otherwise you'll end up with pilot induced oscillation. At least this is what I've experienced flying tail a RW tail dragger.

 

The initial P-51D beta didn't appear to have adequate rudder authority to keep the nose straight at low(er) speeds. This doesn't seem quite right to me, but I've never flown a real P-51D. I've also not flow it since the latest patch or two so I'm not sure if this has changed.

[Der_Fred]

A bit of right rudder trim, set the prop pitch/speed setting to halfway to start with. Slowly increase throttle till the MP is top of green.. then I play with the prop pitch/speed setting. To much bite with prop pitch and your off to the left of the runway. Slowly increase the pitch bite, while stepping on the right rudder. At about 100 mph she comes unstuck. :)

[benargee]

Watched your video. Skip the step where you trim the rudder, or only trim a tiny bit.

 

this wasnt me flying, it was a prerecorded track from the developer:doh: