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P-47 is poorly represented


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BCI-Nazgul
4 hours ago, unreasonable said:

 

This myth is immortal. It is, after all, just another version of the St. George and the Dragon myth, in turn a version of the generic "hero slays monster and gets female reward" myth, repackaged for the History Channel generation. 

 

Of course most believers identify the P-47 as George and the Dragon as the Tiger,  but given some of the comments here over the years, it would not surprise me if a few "critical thinkers" identify the Tiger as St. George. 

Kill a Tiger?  Maybe with extremely lucky shot somewhere to the top engine grate like 1 in 1000 or something.  However, many German other armored vehicles can be penetrated from a top down attack by the .50 AP round and external parts can be damaged as well (main gun barrels, tracks, periscopes, reserve fuel, external weapons, etc...)  So, it depends on your definition of "killed".   If "killed" means immediately explodes, catches fire, many of the crew killed or wounded, then the answer is no.  If killed means rendered combat ineffective either temporarily or permanently then the .50 can do that to some German armored vehicles although the Tiger is extremely unlikely to be damaged this way.   Many tanks were abandoned by the Germans not because they were not total losses, but because they weren't combat worthy and since they were usually retreating there was no way to recover them for repairs.   A broken track is as good as dead if you can't go back and fix it later.

5 hours ago, DSR_A-24 said:

I think simply by nature of the P-47's larger size we would expect it to take more punishment. Not in the sense that it is BUILT more rugged than Bf-109, but its large size grants it room to play with by enemy gun fire having less effect over a larger area. The photo of the 109 you shared has a wing area of 172.8 sq ft vs the P-47's 300 sq ft. A B-17 has a wing area 1,420 sq ft. I think it safe to assume a 1x20mm shell on a B-17 is no near is deadly as it is on a Bf-109.

Exactly.  And a larger airframe and more weight also means that the internal structure (spars, landing gear, and such) has to be built stronger/thicker to support that weight under stress.  This also improves the overall toughness of the plane.   That's the same reason you don't hunt large game with a .22 rifle and why the Germans used 30mm guns because big bombers take more damage to shoot down than fighters, so you need bigger weapons.

Edited by BCI-Nazgul
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Yak_Panther
On 10/14/2021 at 5:53 AM, JV69badatflyski said:


Cool, another history legend coming back....
Could you provide numbers? , the one thing i remember is the "stick in concrete" when reaching the compressibility at M0.79(+/-) and the impossibility to move the plane in any direction.
In a 190 you needed 27kg stick force to retreive from a 80° dive at M0.79  . If you can provide something like that, that would be great to continue the discussion.
thank you.

The test states that the pilot of Fw-190 was not able to pull the aircraft out of dive at mach .79. The aircraft was uncontrollable until it descended 2000 meters and slowed down.  

That test is another example of the compressibility issue, which was a problem on many of the aircraft of the era. 

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The 190 experiences the same loss of control due to compressibility as the P-47 does at nearly the same mach.

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In both cases deflection of the stick will cause the elevator to move. However the pitching moments generated by the elevator are not enough to stop the dive, due to the increase in longitudinal stability encountered in the transonic region.  

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Since the aircraft cannot be pulled out of a dive over the critical mach; The dive continues, the mach effects cause a rapid increase in drag.

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The aircraft reaches terminal velocity shortly after and the dive continues.

 

As altitude decreases, the air density increases, and thus the drag force increases on the aircraft. Which causes the aircraft to slow below the critical mach. Thus reducing the compressibility effects and allowing the aircraft to be pulled out of the dive. 

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This phenomenon is occurring during the 190 dive test, The 190 is only pulled from the dive after it slows below the critical mach number.

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Which is similar to what happens in a P-47

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The behavior is common to most aircraft of the era. If you look at the dive recovery section of many aircraft manuals they offer similar advice.

  1. Leave the power on. The propeller adds a pitch up moment.

  2.  Do not increase the trim, this will just break the wings off once the aircraft slows.

  3. Maintain constant back pressure

  4. The aircraft will recover suddenly at a lower altitude

Tempest:

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P-47 N, which does not have a dive recovery flap:

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The cause of the compressibility effects are summarized in various NACA documents of the era.

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https://ntrs.nasa.gov/citations/19930091992

 

The NACA’s answer to the compressibility issue was the dive recovery flap. It’s not the same as an air brake, as the dive recovery flap doesn’t create enough drag to slow the aircraft considerably. On the P-47 it was noted that the flaps only reduced the velocity by 2%.

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https://ntrs.nasa.gov/citations/20150019985

The primary effect of the dive recovery flap is to change the pitching moment coefficient of the aircraft.

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 NACA RM A7F09

https://ntrs.nasa.gov/citations/19930085641

 

The aerodynamic interaction of the dive recovery flap on the aircraft. Depends on the airframe. On the P-38, the dive recovery flap has a larger effect on changing the angle of attack of the tail then on the P-47. 

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The changing in pitching moment due to the dive recovery flap on the P-47, is primarily a result of the dive recovery flap changing the attack necessary to maintain a constant lift coefficient. 

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Meaning the dive recovery flaps alter the relationship between angle of attack and lift coefficient.

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The effect of the deploying the dive recovery flap was an almost instantaneous pitching moment.

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The trim system used by the 190 and the 109 do have some advantages when it comes to compressibility. The system used by these aircraft changes the elevator's angle of attack. Similar to the interaction of dive recovery flap on the P-38. The change in elevator angle of attack may make it possible to recover from a compressibility event with a combination of trim and a constant stick force. However using max trim and pulling full aft on the flight stick can cause excessive G load leading to black outs and destruction of the wings. It seems like Messeerschmitt wanted to make it possible to pull the K-4 out of a compressibility dive without using the trim system. Flight testing of the time and the various changes to the K-4’s elevator and it’s gearing seem to indicate this too. 

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