Insight into the magnitude of forces involved in dogfights during WW2

[drgondog]

Soren,
Can I ask where you get the information that the Laminar airfoils in a P51 would means sharp and unpredictable stalls in high G turns.

I can tell you from personal experience that a LOW speed stall in a turn for a 51 will get your attention.

The Pilots notes disagree pointing out that its stall is mild and there is little tendancy to drop into a spin.

Glider - The classic stall in level or climbing flight is gentle and predictible.

The danger (to both a Fw 190 and a 51 in a high speed turning/manuever stall) is that you can end up in a flat spin if you aren't on your toes. I think the Fw 190 had the reputation of recovering from a spin better and faster than a 51.

You do not want to be tinkering with spins in 51s if avoidable

 

[Glider]

From the other postings the 190 doesn't seem to be much better

 

[Soren]

Bill,

We agree.

Glider,

Bill is right, the P-51 suffers from unpredictable and dangerous stalls in high G turns. Unlike the FW-190 which recovers emmidiately from a stall a P-51 will often loose 9,000 - 10,000 ft in a spin.

The FW-190 has a very predictable stall if the ailerons are correctly adjusted, something which clearly demonstrated with EB-104 and the Dora tested by the USAAF:

From RAE report (G3 Jabo):
G. Stalls Stall Warning.

The airplane has a gentle stall and controls remain effective up to the stall. Adequate warning of the stall is given by shaking of the airplane and controls.

From post war USAAF report (Dora):

The above agrees completely with what LW veterans say.

Eric Brown notes the aileron reversal which in itself is a clear sign of ill adjusted ailerons, and so is the unpredictable stall as proper adjustment would ensure ample warning of a stall. The waaay premature stalling speed of the airplane at 127 mph is also yet another clear indication of ill adjusted ailerons.

 

[drgondog]

Bill,

We agree.

Glider,

Bill is right, the P-51 suffers from unpredictable and dangerous stalls in high G turns. Unlike the FW-190 which recovers emmidiately from a stall a P-51 will often loose 9,000 - 10,000 ft in a spin.

Soren - My experience in the 'abrupt and nearly unpredictable' stall was with the low speed turning stall. The high speed stall in high G turns gives you plenty of warning and notice. The 51 controls get stiffer at high speed but still very nice at 400mph..

The FW-190 has a very predictable stall if the ailerons are correctly adjusted, something which clearly demonstrated with EB-104 and the Dora tested by the USAAF:

From RAE report (G3 Jabo):
G. Stalls Stall Warning.

The airplane has a gentle stall and controls remain effective up to the stall. Adequate warning of the stall is given by shaking of the airplane and controls.

Same with 51

From post war USAAF report (Dora):

The above agrees completely with what LW veterans say.

Eric Brown notes the aileron reversal which in itself is a clear sign of ill adjusted ailerons, and so is the unpredictable stall as proper adjustment would ensure ample warning of a stall. The waaay premature stalling speed of the airplane at 127 mph is also yet another clear indication of ill adjusted ailerons.

Soren - I would doubt seriously that there is much to choose from at medium and high speed manuevers in context of stall and stall warning betweeen these two ships.

 

[Soren]

I agree Bill, the only difference would be the nasty spin the P-51 has a habbit of entering, quite a few -51 pilots have lost their lives to this, one very recently.

Bottom line however is, the FW190 P-51 both give plenty of warning of a stall.

 

[drgondog]

I agree Bill, the only difference would be the nasty spin the P-51 has a habbit of entering, quite a few -51 pilots have lost their lives to this, one very recently.

Bottom line however is, the FW190 P-51 both give plenty of warning of a stall.

I basically agree - don't push the Mustang into a spin, especially an inverted one.. but I wouldn't describe it as a habit except for possibility that lesser skilled/time pilots would be more prone to this before they had a feel for the airplane.

I would have classified myself this way. This is NOT an airplane a 200 hour total time pilot should be yanking all over the sky. There are consequences.

Having said that, my experience with it was that it was a Delight to fly - with few nasty surprises. The low speed turning stall was one, and the 20+ degree flap condition, torque stall at low speed is a killer at low altitude.

 

[FLYBOYJ]

quite a few -51 pilots have lost their lives to this, one very recently.

There have been 2 spin stall P-51 accidents in the past 10 years, the last two in Hampstead, NC in November of 2000, the other in Urbana, IN in Feb. 2003. In the first accident the pilot was taking off and stalled, spun when turning crosswind - the NTSB attributed that to the pilot not maintaining a speed above Vso on takeoff. In reading the NTSB report it seems the pilot was "shoving" the aircraft into the air as he lifted off within 1000'. This was confirmed by witnesses on the ground. The Second accident occurred because the pilot spun the aircraft at 1,500 feet AGL. He was seen doing low altitude aerobatics by several witnesses. According to the NTSB report the POH for this aircraft allowed power off spins only if they are started above 12,000 feet.

In both cases this seems to be attributed to pilot error and not the fault of any characteristic of the aircraft.

 

[Soren]

Soren,
Can I ask where you get the information that the Laminar airfoils in a P51 would means sharp and unpredictable stalls in high G turns.

Common aerodynamics buddy. The unpredictable dangerous stallling characteristics of a laminar flow airfoil is one of the very well known facts about this type of airfoil.

Laminar flow airfoils have rather sharp leading edges, leading to a low critical AoA and the sharp and unpredictable stalls.

Some basic info:
"Laminar flow airfoils were originally developed for the purpose of making an airplane fly faster. The laminar flow wing is usually thinner than the conventional airfoil, the leading edge is more pointed and its upper and lower surfaces are nearly symmetrical. The major and most important difference between the two types of airfoil is this, the thickest part of a laminar wing occurs at 50% chord while in the conventional design the thickest part is at 25% chord.

The effect achieved by this type of design of a wing is to maintain the laminar flow of air throughout a greater percentage of the chord of the wing and to control the transition point. Drag is therefore considerably reduced since the laminar airfoil takes less energy to slide through the air. The pressure distribution on the laminar flow wing is much more even since the camber of the wing from the leading edge to the point of maximum camber is more gradual than on the conventional airfoil. However, at the point of stall, the transition point moves more rapidly forward."

 

[kool kitty89]

The High 'G' stall characteristics of the Fw-190 were caused by the wings warping which resulted in eliptical lift distribution. Correct? Similar to laminar flow wings eliptical wings have sudden stalls as the wing tends to stall "all at once" along the entire span.

However this was not as pronounced on a/c with semi-eliptical wings such as the P-47 with an eliptical trailing edge and a straight leading edge. (unlike the Spitfire which had a near fully eliptical wing, the He 112 even moreso)

The P-51's wing though wasn't a "true" laminar flow airfoil iirc as it was adjusted to be a semi-laminar flow type with the chord farther foreward than 50% (closer to 35%) with a being a compromise between low drag and stall characteristcs. Iv'e read on this on here (on the forum) but haven't seen many sourses though.

 

[drgondog]

There have been 2 spin stall P-51 accidents in the past 10 years, the last two in Hampstead, NC in November of 2000, the other in Urbana, IN in Feb. 2003. In the first accident the pilot was taking off and stalled, spun when turning crosswind - the NTSB attributed that to the pilot not maintaining a speed above Vso on takeoff. In reading the NTSB report it seems the pilot was "shoving" the aircraft into the air as he lifted off within 1000'. This was confirmed by witnesses on the ground. The Second accident occurred because the pilot spun the aircraft at 1,500 feet AGL. He was seen doing low altitude aerobatics by several witnesses. According to the NTSB report the POH for this aircraft allowed power off spins only if they are started above 12,000 feet.

In both cases this seems to be attributed to pilot error and not the fault of any characteristic of the aircraft.

Joe - that very accurately summarizes the cautions and the consequences.

I got caught in the low speed stall once and only once and snapped it but avoided a spin. It scared the living bejeesus out of me - but I had warning as the stick was 'shuddering' and I wanted to see how far I could push it in a turn. My father was in front and guiding me through the process. It was dramatic but easily recoverable

I also experienced the torque stall with same consequences that I think I told you about earlier.

Both would havce been fatal at low altitude but not a problem otherwise.

Too much is being made about P-51 Wing. It was a sweet and honest airplane and even with my relatively low time a fairly easy airplane to fly.

I always thought, and still think the AT-6 was harder to fly from context of a.) taking off in a straight line and b.) landing in a straight line with a little cross wind.

 

[drgondog]

The High 'G' stall characteristics of the Fw-190 were caused by the wings warping which resulted in eliptical lift distribution. Correct? Similar to laminar flow wings eliptical wings have sudden stalls as the wing tends to stall "all at once" along the entire span.

However this was not as pronounced on a/c with semi-eliptical wings such as the P-47 with an eliptical trailing edge and a straight leading edge. (unlike the Spitfire which had a near fully eliptical wing, the He 112 even moreso)

The P-51's wing though wasn't a "true" laminar flow airfoil iirc as it was adjusted to be a semi-laminar flow type with the chord farther foreward than 50% (closer to 35%) with a being a compromise between low drag and stall characteristcs. Iv'e read on this on here (on the forum) but haven't seen many sourses though.

KK _ the two best books on this subject are Mustang by Gruenhagen and the other book (can't remember title) written about Edgar Schmeud who was the Mustang Design engineer.

Both books discuss the evolution of the Mustang airfoil from a NACA series laminar flow airfoils with max thickness at 40% chord. It was an EVOLVED and uniques design but very close to the 40 series with a 15% maximum thickness.

It had a lower CL than classical airfoils with some camber but it DID delay boundary layer separation over those comparative airfoils

 

[Soren]

It had a lower CL than classical airfoils with some camber but it DID delay boundary layer separation over those comparative airfoils

In straight flight. The Critical AoA was lower.

 

[kool kitty89]

The P-39 also had a good warnig before a stall (buffetting) but if you jerked the controls or pused too close to a stall you could enter a nasty spin. The P-51 was similar but much less sensitive to sharp imputs by comparison. Though a snap stall (and spin) could still be entered from rapid elevator force and this could also be used as an escape tactic if the pilot knew how to handel it and had enough altitude. (the plane could loose several thousand feet before recovering)


View: https://www.youtube.com/watch?v=NlfOWZHEGNk


View: https://www.youtube.com/watch?v=mdCm5z2RpI8

 

[kool kitty89]

Just because the WWII G-suit used the same mechanism as Korea/Vietnam/Modern suits doesn't necessarily mean they will be as effective or efficient in operation. (though they may have been)

That said, does anyone have figures or knowledge on the effectiveness of the G-suits in question?

 

[FLYBOYJ]

Just because the WWII G-suit used the same mechanism as Korea/Vietnam/Modern suits doesn't necessarily mean they will be as effective or efficient in operation.

That said, does anyone have figures or knoledge on the effectiveness of the G-suits in question?

Not so much effectiveness, more comfort than anything else, but in principal they worked the same way and the net result was probably the same as well.

 

[alejandro_]

I will post my question here to avoid opening another topic. I am looking for data on anti-gravity suits fielded by US aircraft during World War 2. Barret Tillman gives some information oin his book "Hellcat, the F6F in World War 2". In the US Navy they were known as "zoot suits", and were first tried by three instructors at Cecil field (Florida) in early 1943. One of them, Lt. E.S McCuskey, a tactical officer in VF-8, immediately recognized the value of the suit, as it allowed to pull 1/1.5g more, and without any penalty weight.

McCuskey then inquired about the Z suits and was told that the west coast evaluation team had decided against their use. He then contacted the manufacturer directly (Berger Brothers), and got the suits. Permission was obtained to equip VF-8 with the Z suits, and this made them the only unit in the US Navy to be equipped with them.

Russell Kyler, a P-47 pilot, also mentions the use of G suits in 56 FG (20:00). It seems that Berger suits were available in large numbers since June 1944.

Timeless Voices

Few questions:

- What is the difference between Berger and Z suit?
- Why did the Navy rejected the Z suit when it was so highly regarded by the unit who tried it?