The p38 and docile handling charachteristics or lack thereof.

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wuzak said:

Polar Moment of Inertia is the resistance to torsional deformation, a different property to what you describe.

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Yes, but didn't I describe the resistance to the torsional deformation of the flight path of all the outlying parts of the plane that don't lie along the axis of rotation?

Gentlemen,

Per the video of Chris Fahey flying the P-38:

If he is flying "23 Skidoo", the aircraft is a P-38J-20, AAF serial 44-23314. It probably does not have the boosted ailerons, as the J-25 was the first block of aircraft so equipped.

FYI

Eagledad

eagledad said:

Gentlemen,

Per the video of Chris Fahey flying the P-38:

If he is flying "23 Skidoo", the aircraft is a P-38J-20, AAF serial 44-23314. It probably does not have the boosted ailerons, as the J-25 was the first block of aircraft so equipped.

FYI

Eagledad

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Either Chris is a seriously muscular guy or the tales about arm-twisting heavy P38 ailerons are a little overblown.

michael rauls said:

It made my think about that about half the descriptions of the p38s flight characteristics I had read by both pilots and historians .

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I have never flown one so I dont know, but I do know what the AFDU evaluation of the P38-F in England said in late 1942.

They said it was extremely manueverable, and easy to fly in most conditions, that night flying wasnt great because of the glowing turbocharger outlets and very visible exhaust flames, a turn was very easy to take to the limit because the tail stalled first and gave the pilot plenty of warning.

The critisism in terms of flight characteristics was just that the potential speed of the aircraft had been limited right back due to the compressibility problem, which meant that the pilots were all under strict instructions to not undertake high speed dives (I cant remember what the speed was, but it was clearly low enough to require very specific instructions given to the pilots).

The AFDU were pretty unbiased as far as I can see, and re-tested the P-38F after Lockheed went back and modified it, two months later. They reported that it was considerably faster than the SPitfire at sea level, and was able to basically handle itself against the Fw190 the AFDU owned - provided that steep dives were not attempted by the Fw190. However it should be kept in mind that this was a de-rated 190 engine, so this is with the German aircraft at max climb boost, and not emergency - the P38F and SPitfire IX were both flown for 3mins at each time at maximum emergency settings.

The report basically concluded that the P38 was a superb aircraft and very capable - although sadly the potential was clearly missed early in the war by the compressibility problems and later in operations, lots of engine issues.

The AFDU report said nothing at all anywhere about any sort of "gripes" in general handling or unpleasant aerodynamic surprises (providing you dont dive fast).

In the tests the P38 had an all-American ground crew and pilot.

XBe02Drvr said:

Either Chris is a seriously muscular guy or the tales about arm-twisting heavy P38 ailerons are a little overblown.

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Wes,

He is flying airshow maneuvers which are probably no where near his or the aircraft limits. In combat when maneuvering for a kill or survival you put as much force as you can / what's required to achieve your immediate goals.

The Eagle has A/C and hydraulic flight controls and on a cross country you will get out of the plane all chippy and fresh. Do three to thirteen BFM engagements and you look like a bucket of xxxx when you get out.

Cheers,
Biff

Snowygrouch said:

In the tests the P38 had an all-American ground crew and pilot.

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An average line pilot with average training? Or an experienced test pilot who had gotten over the erroneous misconceptions that were being taught in some of the P38 OTUs in the early days?
Cheers,
Wes

XBe02Drvr said:

An average line pilot with average training? Or an experienced test pilot who had gotten over the erroneous misconceptions that were being taught in some of the P38 OTUs in the early days?
Cheers,
Wes

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No idea, but I would imagine that the pilots of the P38 and Spitfire IX were both likely to be absolutely crack pilots. Otherwise there would be no value in the mock dogfighting.

BiffF15 said:

Do three to thirteen BFM engagements and you look like a bucket of xxxx when you get out.

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Is that due more to control force effort, or to cumulative Gs? Of course I've never done ACM/BFM as pilot flying, but the limited exposure I've had in the back seat, I found quite draining, rendering me useless at work for the rest of the day. (And I was physically fit back then.) Flying acro in civil aircraft (no G suit of course), I found the fatigue quotient to be directly proportional to the aggressiveness and duration of G. Two half hour acro flights in a day was my limit if I had to do any demanding flying later.
Thirteen BFM engagements in a day is WAY above my paygrade!
Cheers,
Wes

wuzak said:

Polar Moment of Inertia is the resistance to torsional deformation, a different property to what you describe.

What you describe is the Mass Moment of Inertia, or simply the Moment of Inertia.

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I stand corrected. Per Wiki:

Note: Polar moment of area should not be confused with moment of inertia, which characterizes an object's angular acceleration due to a torque.

A popular confusion, as I've seen it misused in so many places, from Navy training films, to civil aviation texts, to books and magazines, that I took it for granted as correct. You never know, even when you think you do.
Cheers,
Wes

Thought I`d post the original to back up my paraphrased comments above, AFDU report 28t September 1942 - Location RAF Duxford.

XBe02Drvr said:

Is that due more to control force effort, or to cumulative Gs? Of course I've never done ACM/BFM as pilot flying, but the limited exposure I've had in the back seat, I found quite draining, rendering me useless at work for the rest of the day. (And I was physically fit back then.) Flying acro in civil aircraft (no G suit of course), I found the fatigue quotient to be directly proportional to the aggressiveness and duration of G. Two half hour acro flights in a day was my limit if I had to do any demanding flying later.
Thirteen BFM engagements in a day is WAY above my paygrade!
Cheers,
Wes

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Wes,

To answer your question, it's a cumulative effect of both wrestling the jet and G fatigue (More of the latter).

In the BFM (1 v 1), and ACM (2 v 1) we usually fight with no external tanks on. The aircraft accelerates well, pulls more G and for longer and will wear you out. We usually would fight tank fight (repeatedly hit the tanker) allowing max set ups (fights) per sortie. My record, done several times, was 13. I have untold numbers of sorties where I had more than 10. You are happy but beat when you land. On top of the G's, you are wearing a harness with big fittings (Koch - pronounced coke) on your chest and when maneuvering hard your right bicep will hit it, resulting in some nice bruising. On top of that you are turning and twisting in the cockpit to see guys in your deep six and that results in bruises on both your elbows from hitting the canopy rail.

Also do to repetition you will build up a large tolerance to G. If you did two half hour sorties every day for a month you would be surprised how well you would be able to take it. I gave probably 25 incentive rides and I learned quickly what to do, and not to do. Of those I had one guy, a fairly buff looking crew chief, who could take more G than me. I was amazed and kept stepping up the G and never had him call uncle. Very unusual! Giggled like a school girl the entire time. His was probably the best one I ever did!

Cheers,
Biff

Gentlemen,
Good afternoon from Reno, Nevada, home of the Nat'l Championship Air Races. A quick prologue: I'm a VFR licensed private pilot w/ a multi-engine rating. I've read a lot of discussions on the merits & disadvantages of the Mustang & P-38 as well as references to WASPs & other aircraft with great interest. Everyone who has contributed to this post have been very articulate & knowledgeable on various aspects of these fine aircraft & I learned a lot. If I may have the honor of adding further to this discussion, I'd like to raise a couple of interesting issues that are also related to this topic.

As in all things in aircraft design, a compromise is given in exchange for a desired performance or flight characteristic; be it speed, long range, maneuverability, high altitude performance & more. In the case of the Mustang's unforgiving characteristics so vividly described by GregP of power-on stalls, what has not been mentioned thus far, are mostly attributable to its laminar flow wings combined with a powerful engine and propeller arrangement. I'm sure we need not to delve heavily into this aspect of the subjects as most of us are already too aware of their influence on the aircraft.

However, what has not been mentioned insofar as some of the neophyte pilot's reluctance to "pull some G's" and thereby ensure their survival, is the fuel tank arrangements. True, Mustangs can have aft C.G.s and this plays a role in the heat of combat. On most early model Mustangs, they only had main fuel tanks in the wings. In effort to extend the range of the Mustang, an extra fuel tank was added just behind the pilot's seat (but under the radio stacks). This act alone will shift the C.G aft. Takeoffs are very dicey at best even under desirable circumstances. The pilots are encouraged to use the fuselage tank first before switching to either the drop tanks or the mains for that reason.

If I may also call to everyone's attention on the twin engines, GregP's description of engine-out on a P-38 with its powerful engines is also worth merit and acknowledged as correct. As a multi-engined pilot, I was taught from the "get go" to immediately accelerate to "Blue Line" after takeoff. This designation is referred to the slowest speed a twin can be flown safely with one engine inop. Once within the Blue Line range or better still, beyond, the plane still needs to be handled carefully, but turns into the dead engine can be made as long as the turn is within reason. The more powerful the engines on the twin, the more likely the Blue Line will be raised to counter the effect of increased torque, P-factor and asymmetrical thrust.. A common killer of most private twin engine planes is due to pilot's inexperience and/or lack of proficiency and during takeoff. Takeoffs are especially "interesting" as the plane is still very close to stall and the engines are developing maximum power. All this and more, needs the pilot's attention at all phrases during climb out. Each twin engined aircraft had its own "Blue Line." Thus, a P-38 will definitely have a much higher Blue Line value to counter most of the effects of one engine out.

Insofar as references to Bonanzas going into the Vne speed zone if nosed down, it depends on how much nose down this plane is going. I've flown the F-33 model Bonanza series and where its true that if I (gently) push the nose down to say, 100-200-feet per minute,, it'll go into the yellow cruise range with ease, with the red line (Vne) still out of range.

Like Mustangs, Bonanzas (& Cessna 337's push-pull twins) have vicious stalls. That's the primary reason behind the small metal strip with its triangular cross section being located at the leading edge wing root. It's to help induce stall at the root prior to the tips to help maintain control. Even then, the wing will drop very rapidly and must be countered with rudder more than aileron. Ask me...... ;)

With regards to XBe's mention of inertia on the P-38's slight delayed reaction from the pilot's controls and counter controls, I don't know about boosted ailerons, but I was also checked out in Cessna twins with tip tanks such as the -310 series. He's definitely got that right! Those heavy tip tanks really induced a lot of inertia!! I would input a control to say a right turn by rotating the control yoke and inputting right rudder for a nice, coordinated turn. When stopping the rotation to maintain the desired bank, I would quickly but subtlety rotate the control yoke to the left and thereby stopping the roll of the aircraft. After awhile, it becomes reactive like muscle memory. that is, until I fly another aircraft.

Finally, I would like to add a bit of insight into the wonderful world of unlimited air racing. What many people may see, are the pilots are flying against each other in a closed circuit at low altitudes around pylons. On top of everything else such as wake turbulence, turbulence from the desert winds, and heat thermals all the while making sure they don't "cut a pylon" , is, gyroscopic procession. Those massive propellers act like giant gyros and the planes were not originally designed for such massive increases in horsepower combined with clipped wings and light-weight airframes at such a high rate of speed. Definitely a challenge even for the most experienced pilots. It's an incredible sight to see and hear in person that cannot be conveyed on televisions.

Skyediamonds said:

Like Mustangs, Bonanzas (& Cessna 337's push-pull twins) have vicious stalls.

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The only Bonanza derivative I have any appreciable experience with is the T34 (about 150 hours), and I wouldn't call its stalls vicious. And I've stalled it all kinds of ways, intentional and inadvertent while out playing "Walter Mitty fighter pilot" in the days of young and foolish. A fully fueled Cessna 210 turbo with a right wing radar pod is much closer to vicious.
I earned my multi in a Doyne converted Apache with 180 hp Lycomings in place of the original 150s and Hartzel props that wouldn't unfeather in flight. Lots of practice at single engine landings. The increased HP meant a higher VMC, and that high lift hershey bar wing wanted to fly long before it was reached. But the mantra was "don't lift off below VMC", so takeoffs were almost always wheelbarrows. Felt like a Huey transitioning forward. I can hear my instructor now: "Stay in ground effect till you reach VYse, then go for altitude." Felt kind of silly calculating accelerate-stop, accelerate-go, V1 and V2 with two miles of airbase runway to take off on, but I got plenty of practice at that, too. Ah, those were the days.
Cheers,
Wes

BiffF15 said:

you are wearing a harness with big fittings (Koch - pronounced coke) on your chest

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That's interesting, our Navy torso harnesses had the Koch fittings up by the shoulders, about where the ripcord is on a sport parachute rig, so you (actually your flight line plane captain) had to carefully position your shoulder straps when strapping in.
Cheers,
Wes

Not entirely applicable but this is what the A&AEE had to say about the Lightning I (Allison V.1710 C15):

Wes,
I salute to you sir on flying the Beech T-34. I was lucky to go for a ride in one & managed about 30 minutes total flying time. We only did a couple of lazy 8's before my pilot friend wanted to land & relax after his cross-country flight to see me.

Insofar as aerobatics, they were in a Great Lakes open cockpit biplane, Citabria & a couple of gentle barrel rolls in a Piper Cub. In all cases I only rode as passenger. In the Great Lakes we did just about every "standard" aerobatic you could think of. However, when he performed the third loop, that's when my stomach said "Okaaay. If you do one more loop, I'm gonna let the pilot know what you ate this morning." Surprisingly enough, I found snap rolls, when viewed from the ground as a spectator, appeared violent. Yet, when my pilot friend executed them in the Great Lakes, they felt so benign.

All of my flying as a pilot were confined to "spam cans," such as Cessnas, Beech's & Pipers. Got my multi in the ol' venerable Apache. You were right in describing its Hersey bar wings. I loved flying it.

Then I flew it's predecessor the Aztec & it was a love affair all over again for about four years until some inexperienced rental pilot bellied it in on short final for running out of fuel. He walked without so much as a scratch, but the insurance wrote the hull off as a total loss. What galled me was the Aztec has four tanks, two in each wing. Pilot training tells us we always land &/or takeoff on the fullest tanks. The Aztec was landing on the inner tanks that turned out to be nearly empty. The two remaining outer tanks were still full.

Gary (Skye)

Lots of skookum commentary here by knowledgable folks. The video with Chris Fahey is instructive. He's extremely knowledgable, former F16 pilot who's logged A LOT of time in Planes of Fame birds (except the 47, I think.) He's active on Facebook warbird pages.

Found this LONG document from Lockheed's Hall Hibbard with some aileron boost references. LiTOT: P-38 design analysis

Doug Champlin's Lightning was an L modified as an M night fighter. He seldom allowed it to be flown, but one occasion I recall involved in-flight failure of the aileron boost. Pilot called reporting potential difficulty in landing so the tower rolled the fire truck. Chas landed fine but said the heavy control response was um revelatory.

Skyediamonds said:

I found snap rolls, when viewed from the ground as a spectator, appeared violent. Yet, when my pilot friend executed them in the Great Lakes, they felt so benign.

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A Great Lakes is not a Pitts. Bigger, heavier, and less powerful. I remember an airshow where they both performed similar routines and the announcer described the Lakes acro style as "majestic". I've had a couple of lessons in a Pitts S2 300, and there's nothing relaxed or "majestic" about its acro style. It's a SNAPpy little bird. It was tricked out as an airshow bird with aileron spades and handkerchief snatch hooks on top of the tail and on the gear and wingtips. It's hard to imagine, but it grosses same as a 152 and that's with a Lycoming 300, two bodies, and two hours fuel onboard. And don't forget the 10 pounds of oil in the smoke tank! Fortunately the regional Pitts/Christen/Sukhoi dealer, acro performer, and airshow promoter lives at the next airport over. He used to give an occasional lesson at $100 a half hour. Not any more.
The T34 was a hell of a deal. Most every Navy flying club had one. Dollar a year lease from Uncle Sam, and free parts and tech support from Training Command in Pensacola. Ours went for $10/hr wet, pre oil embargo. I flew it from Key West to Montpelier VT with 100 hours total time in my logbook, and a five hour check-out.
Cheers,
Wes

Barrett said:

Doug Champlin's Lightning was an L modified as an M night fighter. He seldom allowed it to be flown, but one occasion I recall involved in-flight failure of the aileron boost. Pilot called reporting potential difficulty in landing so the tower rolled the fire truck. Chas landed fine but said the heavy control response was um revelatory.

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I don't know how revealing that is, have you tried driving a car where the power steering isn't working, or even just started driving a car without power steering after a long time driving cars with it.