Author Topic: Need help, P-51 wing innovation (Read 592 times)

Latrobe · « **on:** September 14, 2007, 08:50:49 AM »

For my LAC class I have to write an essay about a topic I know alot about, so I picked "Combat fighters change from ww1 to now". However, I'm stuck on what the P-51 wing design was called. Anyonw know what it is?

Chairboy · « **Reply #1 on:** September 14, 2007, 08:56:09 AM »

You mean the laminar flow wing? It's based on a NACA-23.

EDIT: My mistake, it's not a NACA-23. Found this:
"AA/NACA 45-100 on models up to the H, the H used NACA 66-(1.8)15.5 root & NACA 66-(1.8)12 tip."

Golfer · « **Reply #2 on:** September 14, 2007, 08:58:27 AM »

Not Anyone Can Asssume...what it was called.

Lately Almost Millions In Nevada Are Raped For Lots Of Wampum.

Seriously I used 3 words in google as a litmus test and found everything you'd ever wanted to know.

Latrobe · « **Reply #3 on:** September 14, 2007, 08:59:49 AM »

Ah! Thank You!

Now just have to finish this essay.

Latrobe · « **Reply #4 on:** September 14, 2007, 09:00:33 AM »

Quote

Originally posted by Golfer
Not Anyone Can Asssume...what it was called.

Lately Almost Millions In Nevada Are Raped For Lots Of Wampum.

Seriously I used 3 words in google as a litmus test and found everything you'd ever wanted to know.

I tryed google, couldn't find anything.

Golfer · « **Reply #5 on:** September 14, 2007, 09:04:51 AM »

You didn't try very hard.

Type in..

P-51 Airfoil Design.

AquaShrimp · « **Reply #6 on:** September 14, 2007, 09:24:18 AM »

There is a big thread in the Aircraft and Vehicles forum just on the P-51s wing. The consensus there was that the P-51s airfoil was a modification of a NACA design.

It may be out of the scope of your essay, but one of the engineers who designed the P-51, along with Bud Anderson, discount the laminar flow wing's effect on the success of the P-51. Laminar flow wings need very smooth air, along with a dent free surface (even a piece of masking tape can disrupt laminar flow) to produce a laminar flow.

The Mustangs true claim to fame was by utilizing the Meredith Effect to recover engine power lost from cooling drag. Most World War II aircraft utilized 10% of their engine power for engine cooling (radiators cause alot of drag). The Mustang got away with only using 1-2% of its engine power for drag. It did this by using the radiator scoop as a jet. Hot cooling fluid from the engine was piped into the radiator scoop. As the hot air expanded inside the radiator, it was forced out of the back of the radiator with significant force. To give you an example of how forceful this was, the P-51s engine produced 1000 pounds of thrust at full power. The radiator could produce 375 pounds of thrust at 400mph. The radiator had an adjustable rear door, which automatically configured itself to the most productive configuration- similar in concept to the turkeyfeathers of an afterburning jet engine.

Latrobe · « **Reply #7 on:** September 14, 2007, 09:28:06 AM »

That's the problem. I didn't know what to call it. I tryed "P-51 wing design", "P-51 innovations", and just "P-51". I got info on the cooling system, air intake, bubble canopy, and all the info I could want, but nothing on its wing design.

I know it's a school assignment, and that I should do the research, but I just couldn't find what I was looking for. I clicked on about 50 links and found nothing and started getting a little frustrated, so I deceided to ask the "Professionals"

Phaser11 · « **Reply #8 on:** September 14, 2007, 10:33:51 AM »

Go here, read, do work.

http://www.aviation-history.com/theory/lam-flow.htm

eskimo2 · « **Reply #9 on:** September 14, 2007, 03:44:39 PM »

Quote

Originally posted by AquaShrimp
There is a big thread in the Aircraft and Vehicles forum just on the P-51s wing. The consensus there was that the P-51s airfoil was a modification of a NACA design.

It may be out of the scope of your essay, but one of the engineers who designed the P-51, along with Bud Anderson, discount the laminar flow wing's effect on the success of the P-51. Laminar flow wings need very smooth air, along with a dent free surface (even a piece of masking tape can disrupt laminar flow) to produce a laminar flow.

The Mustangs true claim to fame was by utilizing the Meredith Effect to recover engine power lost from cooling drag. Most World War II aircraft utilized 10% of their engine power for engine cooling (radiators cause alot of drag). The Mustang got away with only using 1-2% of its engine power for drag. It did this by using the radiator scoop as a jet. Hot cooling fluid from the engine was piped into the radiator scoop. As the hot air expanded inside the radiator, it was forced out of the back of the radiator with significant force. To give you an example of how forceful this was, the P-51s engine produced 1000 pounds of thrust at full power. The radiator could produce 375 pounds of thrust at 400mph. The radiator had an adjustable rear door, which automatically configured itself to the most productive configuration- similar in concept to the turkeyfeathers of an afterburning jet engine.

Wow! I didn't know that, thanks.

Viking · « **Reply #10 on:** September 14, 2007, 06:14:38 PM »

The Meredith effect was nothing new when the P-51 was designed. Nor was it the only, or even first, WWII fighter to take advantage of it. The Bf 109 from the F onwards, Yakovlev series and other WWII fighters had thrust producing radiator designs. The Bf 109F's radiators were designed to take maximum advantage of the Meredith effect.

The P-51's aerodynamic advantage was indeed its laminar flow wings. However, lower drag at high speed came at the price of poorer handling at low speeds/high angle of attack. If was more than a worthwhile trade-off for a high altitude escort fighter.

eskimo2 · « **Reply #11 on:** September 14, 2007, 06:32:47 PM »

Quote

Originally posted by Viking
The Meredith effect:

Viking · « **Reply #12 on:** September 14, 2007, 07:16:38 PM »

As a side note: Meredith was a British aerodynamicist who in 1935 postulated the possibility of creating jet thrust from radiator heat.

AquaShrimp · « **Reply #13 on:** September 14, 2007, 08:23:50 PM »

Viking, laminar flow on a piston engined plane is nearly impossible. The turbulent air from the prop, the vibrations from the engine, and the imperfections in the wing prevented laminar flow.

Sure, some planes had thrust producing radiators. But the BF-109s radiator produced very little thrust. I think around 65 pounds of thrust. Compare this with the P-51s 375 pounds of thrust.

The fact of the matter is the BF-109 uses around 10% of its engine power for cooling, the Mustang uses around 2%. Even the Chief Engineer of the P-51 said that its wing did not perform as thought and did not contribute to the planes performance.

Stoney74 · « **Reply #14 on:** September 15, 2007, 01:48:44 AM »

Quote

Originally posted by AquaShrimp
Viking, laminar flow on a piston engined plane is nearly impossible.

Not true. Prop wash and vibration have nothing to do with laminar flow. You could generalize by saying that any air moving smoothly over a surface achieves "laminar" flow and where air separates it is "turbulent". The term "laminar airfoils/wings, etc. comes from the fact that the airfoil shape is crafted in a way to achieve the greatest extent of laminar flow across the wing. Most airfoils achieve some laminar flow, but the "laminar wings" will achieve more than those considered "non-laminar". Dents and dings can reduce the amount of laminar flow achieved, but since you could assume that all wings on all fighters in the field shared a similar amount of surface irregularities, the P-51 wing, for instance, will have a relatively higher amount of laminar flow than say a P-47 airfoil at the same reynolds number. The greater amount of laminar flow combined with other parts of the airframe geometry reduces drag, thus making the P-51 more aerodynamically efficient.

The P-51's sucess can be considered a mixture of efficient and succesful engineering, excellent performance, a fortuitous time of entry into the war, and better trained (for the most part) pilots.