Contra rotating propellors

[Ack-Ack]

Originally posted by agent 009
My P-38 neighbor told me that these were not a success as they could not be adjusted, feathered what ever the correct word is. any thoughts here? Brits had one that went 460 mph, but never went into production.

The contra-rotating props on the P-38 worked out quite well and you could feather the props on the Lightning.  The WW2 training film in Zeno's website for the P-38 explains what to do when you have an engine failure on one engine during take off.  It mentions feathering the dead prop as part of the emergency landing procedure.


ack-ack

[agent 009]

The MB 3 & 5 are yet another what if of WW2. I don't know why is was not produced, they already had the Spit & resources limited likely suspects.

[Angus]

The "Bear" used to drive by all the time.
They always got an escort from the Phantoms of Keflavik airbase.
It counted hundreds of occasions.
I cannot remember when they gave it up, sending those up here, whether they were ever followed by the F15 which replaced the Phantom.

[Krusty]

Originally posted by hawker238
I thought that was called counter-rotating?

P38 has COUNTER-rotating. MB-5 had CONTRA-rotaing. Big difference.


Main reason they didn't use them was because it was a LOT of weight, and a complex system. Hard to maintain, keep going, and it's much easier to simply put a single prop in (with the engines they had towards the end of the war they decided "who needs contra rotating? We get just as good a fighter with a single prop")

[Widewing]

This fighter was in development designed for a Contra prop. Prototypes flew with a standard prop early in the program and still managed 490 mph. While the P-72A would have been the highest performing prop fighter in existance, it was dropped to pursue the XP-84 (F-84 Thunderjet).



One of the many iterations on the XP-60. propeller vibration issues were never resolved before the project was cancelled.

My regards,

Widewing

[agent 009]

Vibration issues aside. One can't help but consider torque probs being eliminated with this arrangement. Also stall & spin probs are interesting to contemplate with these.

[Tony Williams]

I think that the main driver for contra-props in WW2 was to allow aircraft to take much more powerful engines than they were designed for. The later Spits had over twice the power of the Mk 1, and a single prop to soak up that power would be so big that it would hit the ground on taxying. So you could say that a contra-prop was a simpler alternative to fitting new, longer undercarriage!

Tony Williams: Military gun and ammunition website and discussion forum

[Seeker]

I can see the argument for the extra weight/complexity of contra rotating props on a single engine plane due to issues of torque and disc diameter.

Why would one use the arrangement on a multi engined plane; instead of handing the engines??

[GScholz]

Same argument; prop diameter.

[Angus]

Prop diameter is limited because of RPM, - you do not want the tips breaking the sound barrier.
So, once all other tricks are used up, more blades, paddle blades and so, then you can add a prop!
Get rid of the torque at the same time.
Imagine the Avro Shackleton, basically a Lancaster with 4 Griffon engines, all of those countra rots!

Now, early problems with this device were some, this one the most important:
Translational bearing mechanism. The main thing basically. If it fails, it's quite bad, for then the pitch of the rear prop is not under control any more.
This happened to J.Quill. He needed every HP out of a whole Griffon engine to fly a Spitfire at 110 mph! Or as he put it:
"It must have been a strange experience to anyone watching to see a Spitfire approaching to land at normal speed but emitting the roar of an engine at full throttle. In fact the translational bearing had failed, causing the overall propeller efficiency to drop to almost nothing, and it had therefore taken almost the maximum power of the engine to keep me in flight at all"
(Spitfire, A test pilot's story, p.242)

[Guppy35]

Can you imagine the howling if we had this bird in AH?

Spit 21 from 41 Squadron with contra-rotating prop.  4 cannon and superior to the Spit XIV

And yes Spit 21s were operational before the war ended with 91 Squadron.

Dan/CorkyJr

[38ruk]

Originally posted by Guppy35
Can you imagine the howling if we had this bird in AH?

Spit 21 from 41 Squadron with contra-rotating prop.  4 cannon and superior to the Spit XIV

And yes Spit 21s were operational before the war ended with 91 Squadron.

Dan/CorkyJr

no more LA7 dweebs .....ahhh paradise    8)     38

[JB73]

you allied freaks get that, we then must get this:

[straffo]

How many staffeln  ?
Notice I didn't wrote Gruppen

Originally posted by JB73
you allied freaks get that, we then must get this:

[Angus]

Dohhh.
Firstly, that Dornier never existed in squadron strength.
Secondly, it does not have a contra-prop.
Well, if it did, so did the Walrus