Why still no dive acceleration difference?

[RegRag1977]

Reading this very interesting topic a question has come to my mind: for what reasons did the enginneers at Focke-Wulf tried a four blades propeller on the Fw190V18 high altitude prototype (were the blades longer? was the propeller similar to those on the P51 and P47?). Anyone knows or have a guess?

[Crumpp]

for what reasons did the enginneers at Focke-Wulf tried a four blades propeller on the Fw190V18 high altitude prototype

They were looking for a counter to the B-29 being able to bomb at 30,000 feet and above.

The Germans had no ability to intercept anything at that altitude. The FW-190V18 was one of the designs examined and tested. The result was the Ta-152 series had better performance at altitude and the program was scrapped.

[RegRag1977]

Originally Posted by Crumpp

They were looking for a counter to the B-29 being able to bomb at 30,000 feet and above.

The Germans had no ability to intercept anything at that altitude. The FW-190V18 was one of the designs examined and tested. The result was the Ta-152 series had better performance at altitude and the program was scrapped.

Thanks for the answer Crumpp,

In fact I was very surprised to see a German aircraft with a 4 blades propeller (which is very uncommon, the only other i know is He177 Greif bomber) , so i thought (in my noob mind) this solution would somehow be related to very high altitude flight (after all P47 used 4 blades prop and was designed as a high altitude aircraft, and when the P51 became one too, it switched its three blades for four). To sum up i thought the 4 blades were somehow related to very high altitude rather than to power dive performance. But it was just a noob question : anyway i recognize that i don't know anything about aircraft enginneering! Just trying to try to understand "in broad strokes"...

As for what you said about 4 blades propeller and cowling/wingroot weapons firing through the prop disc, although very rare, there were some aircraft with this configuration:

P39-Airacobra late 4 blades prop and P-63 Kingcobra, 2x50. cal (cowling) firing though the prop disc ;

Nakajima Hayate Ia, 4 blades prop and 2xHo103 MGs (cowling) firing through, and on later Ib version 2xHo5 20mm canon (cowling).

I've found any with as much guns (4) as the Fw190 though, perhaps four blades would have killed the high firing rate of these guns?

[JtD]

Hardly, the electrical priming on the Fw could deal with synchronised fire rather easily. Much better than other systems.

[Crumpp]

Hardly, the electrical priming on the Fw could deal with synchronised fire rather easily. Much better than other systems.

Yes it could compared to a mechanical sychronization but the electrical priming cannot change the limitations of the weapon itself.

As for what you said about 4 blades propeller and cowling/wingroot weapons firing through the prop disc, although very rare, there were some aircraft with this configuration:

Interesting and rare....

I was very surprised to see a German aircraft with a 4 blades propeller

If the performance differences had been noteworthy, I think the Germans would have used a 4 bladed design. As it was, they had good propeller designs and increased chord width which accomplishes the exact same goal of being able to load more power onto the disc.

The Germans also used wood in many of their later designs as it is a much better material for power loading than metal.

[BlackBerry]

If the performance differences had been noteworthy, I think the Germans would have used a 4 bladed design. As it was, they had good propeller designs and increased chord width which accomplishes the exact same goal of being able to load more power onto the disc.

I don't believe that. Broad chord 3-blade prop lost 8% efficiency when a/c speed is around 0.55 Mach, although this design outperforms old design a lot when speed is low.

German had no naca16 airfoil, what they used in WWII is just WWI standard-gottingen airfoils and the modified broad chord version.

For all of WWI airfoils(RAF6,ClarkY,Gottingen), 4-blade design is useless, but for the newly developed NACA16, story is different.

[Crumpp]

I don't believe that.

So?

For all of WWI airfoils(RAF6,ClarkY,Gottingen), 4-blade design is useless, but for the newly developed NACA16, story is different.

Did you read the NACA's own findings on the Clark Y and NACA 16 series?

The 16 series has poor lift production and its only real application was in propellers. It was generally considered to be worse than the Clark Y even in that application. The NACA 16 series was supposed be low drag at high speed and designed for the very high transonic realm. It was a real disappointment to the NACA.

Go back a few pages and re-read it. It will confirm there was no difference at speed and the Clark Y was actually better overall.