Radial vs in-line engines

[Sternjaeger II]

uh, I forgot to ask Crumpp, can you please point me to the source of that page? Sounds like an interesting read.

[Crumpp]

It is from The American Institute of Aeronautics and Astronautics (AIAA) library database and is from a presentation at an engineering conference. It is from the only modern design analysis on the P-51 Mustang and was done with an eye on improvements for one of the Reno racers. That being said, I got my copy directly from the author and can give you one if you like.

[Sternjaeger II]

Originally Posted by Crumpp

It is from The American Institute of Aeronautics and Astronautics (AIAA) library database and is from a presentation at an engineering conference. It is from the only modern design analysis on the P-51 Mustang and was done with an eye on improvements for one of the Reno racers. That being said, I got my copy directly from the author and can give you one if you like.

yes please!

[Crumpp]

Certainly. Send me a PM with your email and I will get you a copy.

You do realize it contradicts almost everything you posted in your last post about the P51.

Particularly:

they took a great deal of care in the design of the radiator system on the P-51

It surely was an efficient and revolutionary system

Supersonic aerodynamics and compressibility were still pretty new and not well understood at the time the P51's radiator was designed. Therefore, they did not correctly slope the intake for normal shock formation. The slope was too steep and separation occurred.

That means high drag. This is confirmed in both later NACA wind tunnel testing and RAE flight testing. It is highly unlikely the P-51 series achieved any of its designers goals of laminar flow or Meredith effect. Interesting enough, the B-24 with the Davis wing in a complete accident of fate, did achieve laminar flow!

[Sternjaeger II]

Originally Posted by Crumpp

Certainly. Send me a PM with your email and I will get you a copy.

You do realize it contradicts almost everything you posted in your last post about the P51.

Particularly:

Supersonic aerodynamics and compressibility were still pretty new and not well understood at the time the P51's radiator was designed. Therefore, they did not correctly slope the intake for normal shock formation. The slope was too steep and separation occurred.

That means high drag. This is confirmed in both later NACA wind tunnel testing and RAE flight testing. It is highly unlikely the P-51 series achieved any of its designers goals of laminar flow or Meredith effect. Interesting enough, the B-24 with the Davis wing in a complete accident of fate, did achieve laminar flow!

Hang on, why you're taking supersonic aerodynamics and compressibility into the equation? No plane of the era was designed to operate at such speeds.

My point was that if compared to other radiators of the era, the Mustang one was by far the more aerodynamically efficient, and surely superior to radial engines.

So you're now telling me that the Mustang wing is not a laminar design?

[Crumpp]

You had a chance to read through the report?

[Crumpp]

why you're taking supersonic aerodynamics and compressibility into the equation?

Well, that is what the report is talking about, Sternjager. Let me know when you have read through it.

Understand too, just because the flow is supersonic does not mean the aircraft is supersonic.....

My point was that if compared to other radiators of the era, the Mustang one was by far the more aerodynamically efficient, and surely superior to radial engines.

On the whole, the Mustang radiator is not so aerodynamically efficient. The duct design is poor at best.

So you're now telling me that the Mustang wing is not a laminar design?

No, I said the Mustang did not achieve laminar flow. That is not the same thing as "designed for laminar flow."

It was designed for laminar flow just as it was designed to achieve the Meredith effect, neither of which occurred.