P-51 Military Vs Civilian Flight characteristics

[aust1n]

Hi, I was just wondering if there was any difference in the actual flying of these aircraft, or if its just systems that are upgraded.
thanks
james

[DHenriques_]

Hi, I was just wondering if there was any difference in the actual flying of these aircraft, or if its just systems that are upgraded.
thanks
james

The main difference will be gross weight and how weight is distributed on and in the aircraft.
Dudley Henriques

[aust1n]

Thanks for the quick reply,

I may have to add it to my collection

James

[Bomber_12th]

Speaking of the real aircraft, Paul Ehlen, the owner of the P-51D "Sierra Sue II", the most WWII-period authentic/accurate P-51 flying today, recently talked about some comparisons between flying it and the Mustang he used to own, "Little Horse". The Mustang he used to own was lightly loaded, as most Mustangs flying today are (no armor plate, and a lot of original military equipment missing), where as "Sierra Sue II" has everything in it that was originally there during the war (all of the armor plating, wartime equipment, guns, ammo, bombs slung under the wings, etc.). Paul mentioned that on take-off, with all of the weight in "Sierra Sue", it tracks better down the runway and you can come right on up to full power early on. However, he also mentioned that with all of that weight, it of course will want to come down out of the sky a lot faster too.

A "civilian configured"/light weight, non-armored, non-armament Mustang is harder to make a 3-point landing with, as the CG is much more forward as well as being lighter overall - it won't settle down in a 3-point attitude as well, tending to float around in ground effect. A "civilian configured"/light weight Mustang is also harder to make a precise touchdown with in a cross wind - easy to get one wing to stall before the other. A heavy, stock military weight Mustang 3-points much easier.

One of the things too that is often described differently between Mustangs that were in original service (WWII through Korea), compared to most Mustangs flying today, is the way in which the ailerons are rigged - originally they weren't as light to the touch/ease of control as they are for the most part on Mustangs today.

[DHenriques_]

Speaking of the real aircraft, Paul Ehlen, the owner of the P-51D "Sierra Sue II", the most WWII-period authentic/accurate P-51 flying today, recently talked about some comparisons between flying it and the Mustang he used to own, "Little Horse". The Mustang he used to own was lightly loaded, as most Mustangs flying today are (no armor plate, and a lot of original military equipment missing), where as "Sierra Sue II" has everything in it that was originally there during the war (all of the armor plating, wartime equipment, guns, ammo, bombs slung under the wings, etc.). Paul mentioned that on take-off, with all of the weight in "Sierra Sue", it tracks better down the runway and you can come right on up to full power early on. However, he also mentioned that with all of that weight, it of course will want to come down out of the sky a lot faster too.

A "civilian configured"/light weight, non-armored, non-armament Mustang is harder to make a 3-point landing with, as the CG is much more forward as well as being lighter overall - it won't settle down in a 3-point attitude as well, tending to float around in ground effect. A "civilian configured"/light weight Mustang is also harder to make a precise touchdown with in a cross wind - easy to get one wing to stall before the other. A heavy, stock military weight Mustang 3-points much easier.

One of the things too that is often described differently between Mustangs that were in original service (WWII through Korea), compared to most Mustangs flying today, is the way in which the ailerons are rigged - originally they weren't as light to the touch/ease of control as they are for the most part on Mustangs today.

Some civilian 51 operators after "civilizing" their airplanes then finding they were running out of trim on final approach due to the cg changes actually mounted lead ingots in the tail cones of their aircraft to help with that situation.
Dudley Henriques

[Ron Attwood]

I've been flying the P51 (mil) a lot over the last few days and I'm struck by how 'twitchy' it is. Now is this a trait or am I being hamfisted? To get a nice straight and level state of affairs I've found impossible. Realism/controller setting as per A2A Standing Orders. If it's me I'm happy. If I've set something wrong I'd love to know.
I'm embarking on a PTO tour organised by SOH with dead reckoning, no GPS and no AP. Jeez it's scary!

[robert41]

I can trim for a fairly nice straight and level flight, but it does not last long. As the fuel is used, weight and balance changes requiring correction with the stick and trim adjustments.

[Bomber_12th]

Ron, is there fuel in the fuselage tank? When the fuselage tank is filled, the aircraft will be very sensitive in pitch and harder to trim-out. And that is the way it really is with the P-51 - only a select few have been restored with a fuselage tank installed, and only a few have actually used it in recent years, since having any meaningful amount of fuel in that tank will modify the flying characteristics quite significantly - to the point of being dangerous, if filled all the way.

BTW, speaking of the P-51 fuselage tank, the original wartime technical order for the fuselage tank states that the Mustang should be flown with 25 gallons remaining in the tank to enhance maneuvering and provide a flight reserve. The restored P-51D "Happy Jack's Go Buggy" (completely wartime stock, with everything in it) has been flown a few times with between 25-35 gallons in the fuselage tank, to test the feel. Even with just that amount (the tank can hold up to 85-gallons), Vlado Lenoch has commented that take-off rotation/lift-off happens "briskly", and pulling into a turn becomes very easy/light (little stick force required).

[Ron Attwood]

Now that IS interesting! I've been flying with a full fuselage tank. I found it sensitive in pitch and roll and it makes for a busy time. I'll get rid of the tank and see how it feels. Thanks.

[Ron Attwood]

Top man Bomber_12th. I got shot of the fuselage tank and she's now like a fiesty horse with a decent bit in it's mouth. Controllable but still with spirit.

[Bomber_12th]

Sounds good, Ron! The P-51 is regarded as being one of the most stable of the WWII fighters to fly, and thus quite comfortable for long-distance flying - a lot of Mustang owners take their aircraft on some significant cross-country flights, and of course without autopilot (of the roughly 175 Mustangs flying today, there are only a few which are equipped with a form of autopilot). However, unless everything is just going your way, the Mustang will never be able to be trimmed-out for complete hands-free flying - you can get it all trimmed out and have it flying straight and level for several seconds, but then you'll find you'll have to be back on the controls making a minor control input here and there.

[robert41]

Yes, with the aft tank full, she is quite a handful.

[renaissanceman]

I once asked my father, who flew P-51s in WW2 Europe, about the fuselage tank. He said he would burn it down to about half before switching to combat tanks.

A fighter pilot's instinct is to burn all external fuel before switching to internal. In the P -51, this could be deadly.

By the way, on almost all model B & C P-51s, the fuselage tank was a field retrofit. I believe only the last block of P-51Bs from the Inglewood plant had a factory installed fuselage tank.

Jim

[DHenriques_]

I once asked my father, who flew P-51s in WW2 Europe, about the fuselage tank. He said he would burn it down to about half before switching to combat tanks.

A fighter pilot's instinct is to burn all external fuel before switching to internal. In the P -51, this could be deadly.

By the way, on almost all model B & C P-51s, the fuselage tank was a field retrofit. I believe only the last block of P-51Bs from the Inglewood plant had a factory installed fuselage tank.

Jim

We didn't have the fuselage tank installed on our 51 so we simply took off on the left tank.
Reason both your dad and I did this was to accommodate the up to 10 gals of gas vapor the carb returned back to the tank. The normal setup for this vapor line was to the left tank so you used that tank for takeoff to make room for all that unused fuel coming back home to roost. If you didn't use the tank INITIALLY that your return line was attached to, you could vent up to 10 gals an hour over the side through the overflow line and that's a lot of lost fuel.
The normal routine for the combat guys was to takeoff on the tank the vapor return was using (usually the left but some units retrofitted the line to the fuselage tank. After the climb you then used up the pylons if attached, then the fuselage tank, then you started playing with the mains.
The trick was NOT to arrive in the combat area with fuel in the externals and more than 25 gals in the fuselage tank.
I of course didn't have all these problems with just internals to deal with.
Hope this helps a bit.
Dudley Henriques

[Bomber_12th]

By the way, on almost all model B & C P-51s, the fuselage tank was a field retrofit. I believe only the last block of P-51Bs from the Inglewood plant had a factory installed fuselage tank.

Specifically, the first production model of the P-51 that was fitted with the fuselage tank from the factory was the P-51B-10-NA production block, beginning with serial number 42-106429 (the P-51B-10-NA production block was later followed by the P-51B-15-NA production block). All of the P-51B-1-NA, B-5-NA, and B-7-NA production blocks weren't fitted with the fuselage tank from the factory, but as you mention, many of these aircraft were retrofitted in the field (just as an example, James Howard's P-51B-5-NA "Ding Hao!" can be seen in early photos without a fuselage tank filler cap, and seen in later photos with it - Don Gentile's P-51B-7-NA "Shangri-La" being another famous one that was obviously retrofitted in the field). All production P-51C's, starting with the very first P-51C-1-NT, came from the factory with the fuselage tank installed.


These are some quotes taken directly from the July 29, 1944 technical order for operating the P-51 series airplanes with the 85-gallon fuselage tank installed.

Take-off will be made on fuselage tank and continue to use fuel from fuselage tank until approximately 25 gallons of fuel remains. The airplane assumes optimum stability and flying characteristics with approximately 25 gallons of fuel in fuselage tank. For this reason, fuselage tanks should be serviced with only 25 gallons when missions permit and this 25 gallons will be allowed to remain for proper landing characteristics.

Caution: The 25 gallons of fuel remaining in fuselage tank will not be used except as emergency reserve. When all fuel is expended, center of gravity moves forward thereby creating a nose-heavy condition and resultant unfavorable landing characteristics.
(The tail-high wheel landings we see so often today were not considered the normal accepted landing attitude in original military use - unless of course you were Col. John Landers .)

Flights in rough air, instrument flying, and maneuvers involving high acceleration will be avoided whenever possible until at least one half of fuel is expended from fuselage tank. The airplane starts to assume normal stability and flying characterisitcs when approximately one half of fuel is expended from a fully serviced tank and reaches the optimum stability and flying characteristics when approximately 25 gallons of fuel remain in fuselage tank.

When flying conditions permit, it is advisable to use fuel from left main tank for short periods of time to prevent overflow since the vapor return line is connected to this tank.