Stall buffet on take off!

[richardaero]

On the take off roll I'm getting the stall warning and stick buffet.
I'm doing all the right things for a tail dragger with a big fan up front, any ideas?
Also I mentioned in another thread, about the wing thickness at the tips, I was at Duxford last w/e and took a very close look at the 47 there. The wing section has quite a sharp edge at the laeding edge but it is well below the section centre line, hope that makes sense. The tips are really quite thin, not as chunky as in the model.
Love it though!

Richard

[AC]

On the take off roll I'm getting the stall warning and stick buffet.
I'm doing all the right things for a tail dragger with a big fan up front, any ideas?
Also I mentioned in another thread, about the wing thickness at the tips, I was at Duxford last w/e and took a very close look at the 47 there. The wing section has quite a sharp edge at the laeding edge but it is well below the section centre line, hope that makes sense. The tips are really quite thin, not as chunky as in the model.
Love it though!

Richard

I noticed that too.

I would guess it is an anomaly peculiar to the simulation for we are indeed stalled out before we reach unstick speed....

in summary, "Ya' can't make stew without cuttin' up some potatas!" or, "Ya' never get nuthin' fer nuthin'!"

The simulated plane knows how to fly but it isn't smart enough to know it is still on the ground during take-off roll.

It knows it doesn't have flying speed but doesn't know it isn't flying,

A patch to fix it would probably break the stall warning indications.

So "Ya pay's yer money and Ya' Takes yer Choice!"

[SD_Research]

The plane is sitting at about 14 degrees angle of attack on the takeoff roll so once it gets to the speed where flying simulation commences, it senses a stall and the stall warning system kicks in. Once you raise the tail, the stick will stop shaking and the stall warning will go off. Yeah, there is nothing in the sim that tells the stall warning not to go off if the wheels are on the ground. That's just the way it works. However, it works to your advantage, you can hold the stick all the way back until the buffeting begins, and then you know it's time to push it forward and raise the tail.

[WND]

One thing that I do (works well for me anyways) that you all might want to try is this:

In any tail dragger I start my takeoff roll using rudder and some brake to keep it going relitively straight and then I tend to "'force" the tail up to a level position.

By doing this, it allows the rudder to come into play quicker, it allows you to see "over the nose" better and it allows the aircraft to pick up speed quicker - thus shortning your takeoff roll. It also keeps you away from the aircraft "mushing" scenario.

Yes, the stall warning will be "blairing" but I know the aircraft is not going to fly until it reaches a certain speed so I basically ignor the "horn"!!

Like I said, this works pretty well for me and I just wanted to pass it on "fuel for thought".

Bottom line is tho that you have to know your aircrafts limitations along with your own and always fly safely!!

[richardaero]

Thanks chaps I can see what your saying, but I have to say that whether it is a sim or not, none of my other fighters do this in the take off roll.
Regarding the last message, I have flown a number of tail draggers for real most of which require a good firm push forward on the stick to bring the tail up and hence the rudder in to full effectiveness. Since flying the fighters on the sim I have been studying the real aeroplanes during take off at airshows, being just down the road from Duxford, and I have noticed that they only raise the tail very slightly and tend to unstick in almost a three point attitude. The P-47 in particular is one of these and it is not depending on who is flying it on a given day, they all do it.
Another machine noted for doing this is the P-51. The Spits don’t seem to do it as much, anyway I could waffle all day, Scott, how about a patch, skinnier wings and a smaller bubble while you are at it!!!?…Cheeky swine!

Richard

[Snuffy]

I couldn't get the 47 off the ground until I saw this thread about using the elevator to lift the tail. Since then I've been airborne with this bird plenty of times.

[AC]

I couldn't get the 47 off the ground until I saw this thread about using the elevator to lift the tail. Since then I've been airborne with this bird plenty of times.

Beginning with the Cub J-3, Most tail draggers ,that I flew, lifted their tail spontaneously as they picked up speed. Originally they had skids instead of tail wheels back there so we got the tail up as soon as we could.

Also, the airflow over the wing blanks the rudder when it is in a tail low position. This was particularly noticeable with the Goonie bird (DC-3) and the C-45 (AT 7 or Beech I8 )

[SD_Research]

I couldn't get the 47 off the ground until I saw this thread about using the elevator to lift the tail. Since then I've been airborne with this bird plenty of times.

Beginning with the Cub J-3, Most tail draggers ,that I flew, lifted their tail spontaneously as they picked up speed. Originally they had skids instead of tail wheels back there so we got the tail up as soon as we could.

Also, the airflow over the wing blanks the rudder when it is in a tail low position. This was particularly noticeable with the Goonie bird (DC-3) and the C-45 (AT 7 or Beech I8 )

This is all truly a matter of getting to know this airplane and using the right technique. The biggest problem in training for takeoffs with this plane was with pilots trying to hoist it off the ground too soon. This is a big, heavy airplane and it needs a lot of runway and airspeed to get airborne comfortably. Once airborne it is very stable and a great airplane. The problem is not getting enough flying speed and not managing the stick by trying to hoist the tail off the ground too soon.

We know, without any doubt, that this plane can be flown exactly as indicated in the manual. We've proven this through a lot of testing. The manual indicates that the tail should be raised at least a foot off the ground before lifting off. This allows you to gain good elevator authority, reduces drag, and lets the wing work more efficiently. Also, the CG is well aft on these aircraft on normal takeoff by design (about 28 percent MAC) which further necessitates the need to get the tail up. Keep in mind, too, that civil aircraft do not have the weight of guns, ammunition, extra fuel, bombs, or many other items and therefore, observation of civil aircraft on takeoff is not necessarily representative of "the Army way" of flying. You need a good long takeoff roll for this bird, but she will do what she's supposed to given the chance. Here is exactly what needs to be done to get the plane to behave as expected:

NOTE: Before flight, CHECK AIRCRAFT WEIGHT. The WoP aircraft load in with all weapons and stores in place and will be very heavy. You must remove these payloads and save the flight in the configuration you wish. Otherwise, the aircraft will load in at weights approaching 16,000 lbs! A normal training mission should be with no weapons or ammunition and only the forward tank full, which will give you a weight of around 12,750 lbs. for the D-25 model. For any weight above 14,000 lbs. it is advisable to use 1/3 to 1/2 flaps. So set up an orientation flight, preferably on a grass runway, at minimum weight before getting started.

--Confirm aircraft weight and loading.
--Line up on the runway
--Hold stick full back
--Lock tailwheel
--Confirm prop is at high RPM
--Advance throttle smoothly, but briskly, to full
--Use rudders to control direction
--Stick will begin to shake
--Neutralize stick when shaking commences
--Hold stick in neutral to slightly forward position at this point
--Resist the urge to hoist the tail up
--Allow tail to lift naturally with stick neutral or slightly forward
--Aircraft will fly itself off the runway with the tailwheel about 12-18" off the ground
--Ease the stick forward to gain flying speed
--Raise the gear
--Retrim as needed
--Go FLY!

Three-point or near-three-point landings are also very much achievable, but again, these take practice, and watch your weight! Set up a landing orientation mission with the proper landing weight of about 12,000 lbs. (or less) and shoot a bunch of landings. You will get it a lot quicker than you'd think.

[WND]

First of all, if I offended anyone with the previous suggestion I made - I apologize - it was not done intentionally!

SD, I wasn't trying to go against the manual when I offered a different takeoff procedure, I was only giving a personal suggestion based on 40+ years of flying real aircraft! I learned early on that I get very uncomfortable breaking ground in a "3 point stance" with the aircraft just above stall speed - waiting for it to decide what it wants to do - when / where etc etc!

IT'S A PERSONAL THING!!!

I do agree with you whole heartedly that you have to know your aircraft and also your OWN limitations which will hopefully allow you to have a safe and comfortable flight!

I enjoy the 47, I think you guys did a great job on it, I find I fly it more than the 51 but I've just added a few personal touches to it when I'm flying it!!!

Anyways, just trying to help out a fellow "simmer".

[SD_Research]

First of all, if I offended anyone with the previous suggestion I made - I apologize - it was not done intentionally!

Don't even worry about, no offense taken at all!

The point is well-taken, and the lifting of the tail is always advisable with a conventional-gear airplane. The same applies to this P-47. Lift the tail, but don't force it up. It's a matter of "feel". We just want to make sure that folks know it can be flown "by the book" as we've said, but the takeoff and landing part of it takes a day or so of practice to get just right. In truth, it's easier to hoist the tail to nearly horizontal and get some good flying speed up, just like it's easier to do a wheel landing (and as the manual says, there is no harm in that). But she will take off and land in close to a three-point attitude, but just as in real life, this is easier said than done. But it CAN be done.

[WND]

I agree and understand what your trying to convey!

Over the years I've spent a lot of money just doing takeoff's and landings - you get to know your airplane real well after a while!!

Talk about speed - I crewed my brother's 51 for 8 years and him being an airline pilot at the time (we all know they like speed), his normal approach speed "over the fence" was about 120 KNOTS!!! I guess that's why he put "p-63" brakes on it - twice the area of the stock one's!

Have a good evening

[GT182]

WND, which P-51 does you brother fly? And, has he been to Mid Atlantic's WWII Weekend in Reading Pa. with her lately? I belong to the meuseum and am there every year that I can, maybe I've seen her and had a chat with him. Hope to see you there someday... maybe this year. I work the Main Gate so I'm always around.

Everyone is looking forward to this years show as the Canadian Heritage Museum's Avro Lancaster will be there along, with the only flying Bf-109 in North America.

[WND]

GT:

He USED to own "Double Trouble Two". Sold it in 1991 and it went to Switzerland. I found out a couple of months ago that in 2004 it came back to the states - now owned by a place called "Fighterfactory" in Virginia.

[GT182]

Thanks WND..... at least she's back home now. If you get the chance check out http://www.maam.org/wwii/wwsched.html

Maybe we'll se you there if you can make it.

And found this interesting bit of info.... http://www.courtesyaircraft.com/N9563Z% ... 20Spec.htm

[GT182]

Yes she is... I just found their site and pictures of here here.... http://www.fighterfactory.net/airplane- ... photos.php

Looks like they're taking good care of her. BTW, it looks like the Fighter Factory has quite an inventory of aircraft with some very interesting histioies. I'd say the most nororious would be the PBY-5A they have. Interesting reading to say the least, for all their aircraft.