Wing bending measurements while in level turning flight

[Gaston444]

Hello everyone.

I wanted to know if, for low wing single engine nose-driven prop aircrafts, there has ever been a measurement done, while in flight, of the actual amount of wing bending occurring during sustained level turns at a measured G force, including full power sustained turns.

The aircraft types I am interested in would have to be similar in size, power and configuration to a typical WWII fighter: Nose-driven low-wing monoplane of at least 1000 hp and weighting at least 5000 lbs. A Piston engine would be much preferred as well, but a turboprop's data could be of some use.

I am guessing a simple camera looking straight down the wing leading edge could have been used in the early 1950s to measure wing bending in turns...

This question is quite important to me, and I have asked several places with no replies, so I hope this is the right forum to ask... The problem I see here is that my question is more historical in nature than pure engineering.

The reason why I am asking this is because I have seen too many clues from WWII combat accounts that call into question the notion that nose-driven tractive propulsion behaves in the exact same way as rear (jet) propulsion during sustained turns. Specifically, the described phenomenon of reducing the throttle yielding a no-delay (no deceleration delay at all: I do mean Instant) large and indefinite duration advantage in low speed maximum sustained turn rate at around 3.5 Gs. This advantage in turn rate implying of course a much tighter radius but at a slower speed.

Best sustained turn rate on a Me-109G-6, with strong pilot emphasis on using a much reduced throttle, is described as 160 MPH by this pilot (barely 55 MPH above stall speed), while that type's safe airframe limit of a minimum speed 6G "Corner Speed" is said to be around 220-240 MPH...

I have a theory that explains this, but it could easily be disproved if a test was done that shows wing bending measurements at various speeds and power levels while in a level turn (dive pull-outs don't count, and power preferably must be close to maximum for one level turn wing bending value at least).

I know very well what the basic theory is, and why it makes this sounds impossible: I really do want to find out if wing bending was ever measured while in level sustained speed turning flight, at high power, on these types of aircrafts.

Thanks in advance for your help.

Gaston

 

[Gaston444]

I have just been told there is something called a strain gauge inside WWII fighter cockpits that gives flight instrumentation for wing bending...

Anyone knows how they work, or how they are calibrated? How is the data correlated to actual stresses on the wings?

Thanks in advance. G.

 

[NatSusan]

Hi Gaston,

That's a really interesting question you have there. I'm not an expert in aircraft engineering or history, but I did some research and found a few possible sources for you.

Firstly, I came across a book called "Aircraft Structural Analysis" by Jack Petersen, which discusses the design and analysis of aircraft structures. In chapter 12, it mentions that wing bending tests were conducted on a variety of aircraft, including the P-51 Mustang and the F4U Corsair, during the 1940s. These tests involved applying a known load to the wing and measuring the resulting deflection. However, I couldn't find any information specifically on wing bending during sustained turns.

I also found a forum thread on the website Warbird Information Exchange, where someone asked a similar question about wing bending on the P-51 Mustang during high speed turns. One user responded that they had seen a video of a P-51 doing a "full power sustained turn" and that the wing was visibly flexing. However, they didn't provide any further details or sources for this information.

Another possible source of information could be the National Advisory Committee for Aeronautics (NACA), which was the precursor to NASA. They conducted a lot of research on aircraft during the 1940s and 1950s, and they may have some data on wing bending during sustained turns. You could try searching their online archives or contacting their research center.

I hope this helps, and good luck with your research!