At last years Nats I was very interested in Seeing Brenner Sharp's Contra-drive fly. I watched it fly and I talked with him at length. I have always been interested in contra-drive systems. When I was invited to my first TOC in 1982 at the urgings of my good friend Harry Roe, I designed and built a twin engine contra system. I didn't get everything working reliably enough to use it at the TOC, and then I never did get back on the idea. But with electric and the engineering skill of Brenner it is now very possible. Of course, it has been used successfully by others, but Brenner's system brings it to a possibility for more of us.

Brenner was kind enough to send me a unit to try and I installed it in my Onas. After about 25 - 30 flights so far, I have to say this is the only way to fly! Brenner sent me several different gear ratios and two different size prop sets. I have settled in on the 9.8 to 1 ratio and the 22x20 props. It has taken some changes to the trim settings and throws on the model, but the way the model flies so absolutely symmetrical has to be felt to be believed. Just about everything has improved. This set-up has incredible vertical power, but the horizontal speed is easily controlled. The downline braking, even without the use of ESC braking, is excellent. Snaps are improved. Vertical rolls are like they are on a string. Stall turns are much easier and cleaner.

I am still working on set-up, and time will tell about the final success. But these recent flights have just sort of been a dream since 1982 finally realized. I wish I had the engineering skill and the fortitude to have worked it out a long time ago. My discussions with Brenner have shown me how smart and driven he has been to bring this unit to life. It is soo very neat for me to see such a wonderful piece of engineering for the hobby come with a "Made in the USA" sticker!

Here are a few pics of my Onas. This is the same one I used at last years Nats.

A little more data. I have been using both my TP 5300 Pro-Lites and the Neu 5000 25C packs I used at last years Nats. A Masters pattern uses about 3500 mAh. I set my timer now to 7:10 and that gives me the Masters pattern and a maneuver or two. This is starting the timer after I taxi out, just before take-off, then flying to the timer, setting up and landing, with the taxi back. If I do that it takes about 3900 to 4000 to charge the packs. The Neu motor has been just barely warm to the touch after landing. That is with no baffling in the model. I am borrowing a good scale tomorrow and I'll know what the weight difference will be then. I can pull weight out as the mounting I made to install the unit still uses all my existing bulkheads. If I remove them and start over I will save some weight over the shims and mounts I made to install it now. BTW, the Onas had 5 degrees of right thrust. Seems like a lot, but it was what worked. Taking that all out sure is nice!

Tony, congrats on realizing the dream.

Your CR systems in '82 were very cool! An idea perhaps just ahead of its time!

Thanks Mike. It's all due to Brenner and his work. And to Harry Roe back in 1981 who pushed me to make my contra drive.

Here's a pic I'm sure you'll get a kick out of. My first "real" pattern plane was a Phoenix 6 in 1976. The 7 is the same thing other then a thicker stab that's mounted a little higher. I took this pic after getting the first flights on my new Hangar 9 Phoenix 7. What a kick it was to fly that design again! After looking at all the "modern" pattern models I kept thinking as I put the 7 together, this just isn't going to fly well. Boy, I wish my 7's in 1978 flew as well as this one! Tracks like it's on rails, rolls like a dream. Just a blast! And finishing the flight with a nice, nose high, held off the runway forever landing. Sent a chill up my spine!

I got another 8 flights on the Contra equipped Onas today. Got to fly it in some 20 MPH winds. I think they will probably outlaw this thing. It flies so good it's like cheating!

Thanks for your evaluation Tony.

I have mixed emotions on the possibility, but ultimately I hope "they" don't outlaw contra drives.
Part of the appeal of pattern for me is that the planes fly so darn good that, competition or no, it's just plain fun and satisfying to fly them. Technical developments have made them better and better over the years (IMO).

Also, Brenner et al. have done a heck of a job engineering and producing this thing, and they deserve to make some money from it.

On the other hand, there will be plenty of people (like me) with more money than talent who will need or want it, thus driving up the perceived cost of being competitive. It's not going to lower the cost of the hobby! I apologize if my comments send this thread off into the cost debate - no need to as this is being discussed elsewhere.

Dan

Hey Tony, congratulations on getting such a great system into the air. I have only seen one aircraft with a contra-rotating system in the air and I thought it was particularly noisy. How do you find the noise levels of the setup?
All the best, Simon

I was just kidding about it being outlawed! It will be an added cost, but you have to fly one of these set up right and you'll be hooked.

As for the noise, I find it to be pleasant. It seems to be no louder then my standard set up. It's different, but really not louder. I suspect it will measure quieter on a noise meter, as the props are only turning about 4K. Brenner increased the prop separation from the unit he flew last year and that did make it quieter.

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I'm not sure it's going to be a "perceived" cost once this thing starts production and guys start winning with it . . .
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It looks like a great piece of equipment and I am convinced it will be great for pattern airplanes <$igh> . . .
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With something like this there are two main priorities:

1/... Developing a system that meets customer needs, and pushes to the edges of the design inference space with regard to same.
2/... Making it available at a reasonable cost.

Right now we are focused on priority #1. Our efforts are directed towards developing a system that takes full advantage of the the Contra Rotating Propeller Concept. We figure that if we don't succeed in this, then someone else will come in and do it in our place.

If we can achieve success with priority #1, then we can focus on cost. However, right now cost is highly dependent on production volume, because in small batch sizes of fifty or so most of the cost goes into CNC setup, and manufacturing burden. As the volumes get higher then material cost and CNC machine time will become more significant, and we can address these costs with better sourcing, and creative manufacturing process development. Investment in tooling helps here as well.

Brenner ...

Keith, with all due respect to Tony and his last response, he used the interesting word "hooked" which correlates to my last repsonse to you in another thread here in the pattern section of RCU.
It should be noted, Brenner is definitely on the cutting edge of design and technology and eventually the sales of his Contra Drive unit will "go thru the roof" and the cost of R&D etc, will be overcome. Then, hopefully the price will come down to a more affordable level and many more of us will be able to afford it. I just hope he continues to sell direct to the consumer because we all what will happen if a retailer gets involved___"It's all about the money"! At this point, I would encourage him to resist the temptation. Regards, Everette

Congratulations! Are you using two motors and two speed controllers, and sharing batteries, or is it independant? Jim

Hi Jim, there is one motor driving the two props with the gearbox in the spinner. Brenner has a thread going in the electric section started last year with several posts showing the unit: http://www.rcuniverse.com/forum/m_9833118/tm.htm

The thread is long but there's a lot of info and worth a look at.

Dave

Thanks for the pic Tony! I was wondering if you got the P7 going and what you thought. I was amazed too when I got it flying. I didnt expect it to fly as well as it did.

Meant to e-mail you and ask about it but dont seem to have your current e-mail addy. Please shoot me an e-mail so I have yours.

Is Harry still around? I havent seen him for any years now.