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P-51 to Valdez?

fsxar177

Long-Time Enthusiast
I'm having a bit of trouble getting any tech support for a peculiar issue, with my A2A Wings of Power Accu-Sim P-51D, civilian model. It's but a small issue, but somewhat fun actually. Maybe I'll take it to Valdez!
Take a look;


- Joseph
 
To me it appears to be operating as designed.. The prop wash is going back to the elevator, and you are commanding nose down with the elevator and the prop wash is picking the tail off the ground. Got an empty fuselage tank so all of the weight is with the V-12 up front and nothing out back. Sure they will be able to give you a more technical reason. There is a placard somewhere on the dash saying not to go over 40"MP (I think) while on the ground with the tail unsecured. The P-40 and Spitfire do this as well. I have destroyed many props on the Spitfire doing power checks without the tail secured (forget) and it nosed over at the blink of an eye.
 
With the Spitfire, you definitely have to be careful of such things (the combination of power/brakes/elevator):

9-MH434-5616Jun91BigginHillImageMEv.jpg


9-ML407Eastliegh5March1986imageJackFrost01aa.jpg


9-PV202DX5July1992BennoGoethalsPeterArnold002.jpg
 
As in the case of the Mustang, you never want to have down elevator with power (anything more than what's needed to taxi). As Steve mentions, they all came from the factory with placards in the cockpit that warn against increasing the power to 40" MP without the stick firmly held back, otherwise you greatly risk the chance of tipping the aircraft onto its nose. With each Mustang flying today ranging in value from about $1.5 - $3 million, no one is ever going to try and find out if their Mustang can do similarly for real.

(Most all Mustangs flying today have lead weights, of varying amount, in the tail (vertical fin) to balance the aircraft to the proper center of gravity, especially due to many of them having a post-war civilian life weight reduction in the mid-to-aft fuselage (though there are also a number of Mustangs flying today in full stock WWII configuration/weight). One of the aspects of civilian Mustang flying that is not often discussed, but has been brought up in the past by real-world Mustang pilots (like Vlado Lenoch), is the effects on the flight characteristics when having a passenger in the back. The vast majority of P-51D's flying today have the wartime radios, armor plating, and fuselage fuel tank removed, and have a jump seat installed (some of them even with basic dual controls). When a passenger is riding in the back it creates a little bit of the same effect as having the fuselage fuel tank with some fuel loaded - for instance, the heavier the passenger, the lighter the elevator forces.)

Contrary to the Spitfire and Mustang, with the Bf-109, which is very tail heavy, pilots often describe having to push the stick full-forward and use bursts of power in order to get it to turn while taxiing, and never having to worry about it nosing over - something that, as they say, would quickly doom a Spitfire.
 
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Thanks for the input fellas,

Certainly the argument isn't, would the tail life, or not. But rather, the control of it, while lifting. It would appear that prop-wash alone would be causing this.

At Thunder Mustang we used to tie the tail down, during full-power ground tests. Mostly on the account of the raw thrust of the propeller, pulling through the brakes.

On smaller racers, Cassutt's and such, it's common for a person to physically sit on the tail of the aircraft, again for lack of brakes. We would also stand in front of the wing during warm-ups.

I would like to try it with more weight. Moth Mil, and Civ. models do this, regardless of a loaded center tank.

- Joseph
 
So the general consensus at A2A is that this kind of behavior is true to type. Go figure!
 
With the Spitfire, you definitely have to be careful of such things (the combination of power/brakes/elevator):

9-MH434-5616Jun91BigginHillImageMEv.jpg


9-ML407Eastliegh5March1986imageJackFrost01aa.jpg


9-PV202DX5July1992BennoGoethalsPeterArnold002.jpg

I do not have a picture of it (I was too busy pulling the tail down and clearing my plane from the runway), but I've done something similar to this in my RV-8 landing several years ago. (Tar across cracks in the runway resulted in a little too much brake pressure.) Once you get the cg on the wrong side of the main gear bad things happen. On windy days, I can lift the tail of my -8 with throttle alone, but it normally take about 25 - 30 mph to get the tail up at takeoff (i.e., takeoff power airflow washing over the tail surfaces). As Bomber12th points out weight distribution along the fuselage has a large impact on cg and the power required to lift the tail surfaces. Each aircraft is weighed at each gear to ensure that the aircraft is within its cg range. In the RW, lots of things impact cg, e.g., passengers, baggage, fuel, location of batteries, bags of lead shot placed by the aircraft builder, etc. etc.

A Mustang having its tail surface lift this way is not unusual considering the power / airflow being generated at 40% power.
 
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