To CR or not to CR?

[Blue Foam]

Are counter-rotating props better than single props?

Yes, there are obvious technical advantages such as efficiency, potentially higher thrust, and lack of p-effect. Downsides include weight, complexity, safety, and finally, balancing the crazy thing.

We grazed on this subject a little while back. Sparrow rightfully pointed out the not-so-great track record. Let's hear from anyone interested, especially those involved with Red Baron, Miss Ashley II, and Precious Metal. The best opinions would come from anyone involved with any aircraft that went both ways.

[spacegrrrl]

Re: To CR or not to CR?

It is my understanding that the non-cr props might be more efficient althought the lack of torque I've been told is nice. It's my understanding that the reason we see counter-rotating props on the gryphons is the 5 blade that is the general alternative is extermely rare and expensive.

Michele

[blacksheep]

Re: To CR or not to CR?

I've always been curious if anyone has ever contacted Russian engineers on the viablity of CR props in a racer.Seems to me they have the most experience in using them as anyone

[440_Magnum]

Re: To CR or not to CR?

It is my understanding that the non-cr props might be more efficient althought the lack of torque I've been told is nice. It's my understanding that the reason we see counter-rotating props on the gryphons is the 5 blade that is the general alternative is extermely rare and expensive.

Michele

Isn't it more that the *gearing* for a Griffon to drive a single prop is what's extremely rare compared to the relatively plentiful surplus Shackleton Griffons with contra-prop gearing?

As for the whole "better or not" question, that's out of my depth. I'm an electrical engineer- I understand what electrons do in semiconductors a whole lot better than what air molecules do around propellers.

If you were starting with a clean page and unlimited budget, my guess is that you could do a great job with a contra-prop setup. But given that air racing Unlimiteds have real-world limits and usually come down to modifying existing engines and parts to take much higher than designed-for power levels... the problem is a lot thornier.

In the other thread, I restated a memory I had of someone claiming that the propeller blade airfoil on the Griffon/Shackleton contra-prop is downright primitive compared to things like the Hamilton-Standard "cuffed" prop used on the Mustang and Aeroproducts props used on R3350 racers. Is that true? Is my memory correct? If so, you'd think that there would be a lot of gain in coming up with a new blade profile to use, along with the secondary oiling-system independent feathering provisions that were discussed.