Need help, P-51 wing innovation

[Viking]

I just found out that Meredith was not the first to suggest creating thrust from a radiator. It seems Hugo Junkers was the first to discover the "effect" and in 1915 he patented his "Düsenkühler" (jet radiator). And he actually included the effect in the very first aircraft he ever built. So why it isn't called the "Junkers effect" I don't know.

Now I cannot say that the 109's radiators were as efficient as the P-51's, to my knowledge no test of the 109's radiators survived the war. However we can assume the P-51's radiator was very efficient for its day, and the wings were very effective for a fast pursuit plane as well. Add to that the P-51 was very aerodynamically clean; none of the bumps and bulges that the 109 and Spitfire had. However the, for some, perhaps uncomfortable truth is that on the same power the 109 is still faster than the P-51. The P-51's Merlin delivers 1790 hp, while the 109K-4's DB 605DB delivers 1800 PS (1764 hp). At least as modeled in AHII the 109K is faster than the P-51D at all altitudes except below 100 feet where I think the Pony is 1 mph faster.

So while the aerodynamic advantages of the P-51 were not so astounding like they are often portrayed they did help the P-51 carry around the extra weight of  the fuel it needed to reach Berlin.

[AquaShrimp]

Bf 109K-4 1x Daimler Benz DB605ASCN 12 cylinder inverted-vee liquid cooled engine rated @ 2,000HP @ takeoff and 1,800HP @ 16,400'.

P-51D-one Packard V-1650 (licence-built R-R Merlin 61-series), originally 1,520 hp V-1650-3 followed during P-51D production run by 1,590 hp V-1650-7

The P-51H had even less horsepower at military power, but more with wep.

[Viking]

Our 109K doesn't have that engine. Our K has the 1800 PS DB 605DB using B4 fuel and MW-50. If we had the C3 fueled engine our 109K-4 would have been even faster.

And at least this site...

http://www.chuckhawks.com/mustang_P-51.htm


... lists the Packard Merlin V-1650-7 at 1,790 hp at 11,500 feet.

[PanzerIV]

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.

That is cool! I did not know that!

[Stoney74]

Originally posted by Viking
So while the aerodynamic advantages of the P-51 were not so astounding like they are often portrayed they did help the P-51 carry around the extra weight of  the fuel it needed to reach Berlin.

Well, that's the key.  P-51 max takeoff weight of 12,000 lbs.  Bf-109K4 max takeoff weight of 7500 lbs.  All that extra weight creates a huge difference in the induced drag created at high altitudes.  Obviously all the other drag components were lower enough to compensate.  So, you could say that the aerodynamic advantages were indeed a large part of the P-51's success as a design.

[dBeav]

Originally posted by Viking
So why it isn't called the "Junkers effect" I don't know.

Winning a war has it's benefits.

[Viking]

Normal loaded weight for the P-51D without external ordnance was 9,200 lbs. Normal loaded weight for the 109K was 7,400 lbs without external ord. Still ... that's a 1,800 lbs difference.

The 109 could carry almost as much external ord. as the P-51, but very rarely did. They had to use a special lengthened tail wheel to fit the 1000 kg bomb under the fuselage. Most only flew with a 250 or 500 kg bomb. There were also special long-range versions of the 109G with provisions for two 300 litre drop tanks.

[Viking]

Originally posted by dBeav
Winning a war has it's benefits.

Must be WWI then since he filed the patent in 1915.

[dBeav]

Winning 2 wars has twice the benefit.

[Viking]

Sure