Propellers on P51, Corsair Hellcat and Thunderbolt

[pinsog]

The P51 had a fat, 4 blade, square tip prop, the Corsair Hellcat and Thunderbolt had a skinny toothpick looking prop even though they had much more horsepower. I know later on they put a paddle prop on the Thunderbolt, but not the Corsair or Hellcat.

Why didn't they put a fat square tipped prop on the Corsair, Hellcat and Thunderbolt? What about a 5 bladed prop on those 3 aircraft? Would a 5 bladed toothpick prop be as effective as a 4 bladed paddle?Would it have helped top speed or climb rate?

I would really like to hear a technical answer from some of you engineer guys. Thanks.

 

[r2800doublewasp]

I dont really have the answer but I know Vought put a 4 bladed prop on the corsair- F4U-4,-5,-7 etc. Dont know about a five bladed one though. (maybe experimental) And I know that N.A. tried a 5 bladed rotol prop with some of their experimentals- xp-51J,G, maybe F,. I dont really remember which one. Will have a look in my warbirds magazine. They did an article about the experimentals a while ago. I think it was the XP-51G. I do know I didnt work out. Hopefully someone else can help.

 

[FLYBOYJ]

Engineers determined what would be the most efficient propeller to be used on those aircraft. You not only have to look at speed and climb performance, but fuel efficiency and loads imposed on the engine and airframe. More blades don't always mean faster or more power.

 

[pinsog]

Wonder why they didn't try the P47 paddle prop on the Corsair and Hellcat? Or did they?

 

[FLYBOYJ]

Wonder why they didn't try the P47 paddle prop on the Corsair and Hellcat? Or did they?

To my knowledge they didn't but paddle blades were used on an experimental P-38 and greatly improved performance.

 

[pinsog]

I read about that P38, it was quite a performer. The reason I asked the original question is that the late model Spitfires had 5 bladed props and I figured if they could use them why not the big radial engined US fighters. They late war Thunderbolt and Corsair both had an abundant amount of hp and I just figured they probably weren't effectively using all of it.

 

[FLYBOYJ]

I read about that P38, it was quite a performer. The reason I asked the original question is that the late model Spitfires had 5 bladed props and I figured if they could use them why not the big radial engined US fighters. They late war Thunderbolt and Corsair both had an abundant amount of hp and I just figured they probably weren't effectively using all of it.

As stated, more blades don't always mean better performance. There's a balance of what the desired end result will be and what you'll have to compromise for. You may get better performance at altitude but loose climb. You may get better climb but burn more gas. Think about this - for every blade you add, you also adding at least 100 pounds or more to the empty weight of the aircraft...

 

[VERSUCH]

Some aircraft had extra blades for the the simple reason of ground clearance.

 

[CPWN]

4 blades on XF6F-6, but also a new engine(the same with F4U-4). Max speed 671km/hr.

 

[robwkamm]

sea furys had 5 blades didnt they ? i have a set of big 60 spline paddle blades. these things are more then 100 lbs each. i thing mine are solids. maybe hollow ones are lighter?

 

[robwkamm]

heres a . hamilton standard prop.

 

[Shortround6]

Going by what they "knew" at the time 3 blade props were considered more efficient. But a larger 3 blade prop was needed than a 4 blade.

Leaving aside what FlyboyJ has said, which is correct as far as I know and he has much more experience than me, it does come down to the designers experience, gut feelings and some calculations. The ground clearance thing is a big factor.
Please remember that around 1940 there were only 12-14 wind tunnels in the US of varing sizes and speed capability. By the end of WWII there around 40.

What they "KNEW" or thought they knew in 1940-42 vs what they KNEW in 1945-46 are not always the same thing.

 

[FLYBOYJ]

Going by what they "knew" at the time 3 blade props were considered more efficient. But a larger 3 blade prop was needed than a 4 blade.

Leaving aside what FlyboyJ has said, which is correct as far as I know and he has much more experience than me, it does come down to the designers experience, gut feelings and some calculations. The ground clearance thing is a big factor.
Please remember that around 1940 there were only 12-14 wind tunnels in the US of varing sizes and speed capability. By the end of WWII there around 40.

What they "KNEW" or thought they knew in 1940-42 vs what they KNEW in 1945-46 are not always the same thing.

Agree

 

[ppopsie]

Large diameter 3 blade propleller. I've been wondering how big was the early B-29's three balde prop. That looks larger than the four bladed ones.

 

[fastmongrel]

I bought a book from a charity shop yesterday " British Aircraft of WWII" by David Mondey. In the section on the Seafire it says that during the invasion of Scicily, because of light winds and the low speed of the escort carriers there were an unusually large number of landing incidents due to the high approach speeds.

MkIIc's flying from the escort carrier HMS Hunter kept damaging the prop tips on landing when the hook hit the wire and the nose dipped. After 3 days they had run out of spare props so to keep flying they cut 6 inches off the blade tips. An effective remedy which became standard FAA practice.

 

[ppopsie]

Seafire> I read the story in "Spitfire" by J. Quill. BTW I am always dreaming of myself flying in a(ny of) the ww2 fighter airplane equipped with a powerful engine and huge diameter prop, as the pilot.

 

[R Leonard]

Take a look at the F8F

R

 

[Shortround6]

A few numbers to think about concerning this.

Weight of 3 bladed propeller on a F6F-3---485llbs
Weight of 4 bladed propeller on an early P-47D---541lbs
Weight of 4 bladed propeller on a P-47D-25---659lbs.

Power at sea level is 2000hp fo rthe first two and 2300hp for the third.

Power at 22,500ft for the F6F-3----1650HP
Power at 25,000ft for the Early P-47----2000hp
Power at 31,000ft for the P-47-25----2300hp.

Since the air gets thinner the higher you go you need a bigger propeller at higher altitude for the same power.

I don't know if the designers got it right but maybe the Corsair and F6F didn't need a four bladed paddle prop to handle the power.

 

[tomo pauk]

That Hellcat proto seems like a neat machine, too bad/good it was not needed