Rotary engines

WHY

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Anybody got any good rumors or even good reliable info on new rotary engines that are in the pipeline. Would like to find a rotary of about 70 to 80 hp for my single place tractor. I think Atkins is building a single rotor from a Mazda 13B but not sure if I can handle the weight with redrive and radiator would guess near 200 pound .

Tony
 

rtfm

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G'day mate,
You will find that there are quite divergant views on Rotary engines, not only on this forum, but on most aero forums. The simple truth is that rotary engines come in for a bit of controversy because they are relatively untried.

Bottom line: a single rotor RX-8 engine will weigh (all up, ready to fly) about 200lbs. Producing about 105hp. Build in some variances, but that's about it. A double rotor (ie standard) RX-8 engine will push double that, with not that much weight penalty. They are good engines. Very few moving parts, high reliability, easy to service. Just why they have a reputation for burning tip seals, or being gas-guzzlers or being difficult to work on beats me. These things are demonstrably untrue. They might have been true 20 years ago but how long must early problems be allowed to overshadow two decades of success? Guys fly these engines every day, and the aviation world (by and large) turns a blind eye. It's to their detriment.

If you like rotaty engines (and I believe liking or disliking them is rooted more in emotional responses than logic) then go for it. I am one of those people who think rotary engines are really great.

Regards,
Duncan
 

rtfm

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Hi,
If you are looking to buy a beatifully built Mazda Renesis (single or double rotor) engine, don't confine yourself to Atkins (who build great engines, by all accounts). Do yourself a favour, and check out the engines crafted by Cobra Aviation in Australia.

Tom is as close to a genuis with engines as we are fortunate enough to find in the aviation world today. The fact that he is little known in international circles is of little consequence. I guess there are many people like Tom Wickers around the world who are masters of their craft, but they just don't get the exposure that the American guys get. So drop him a line and see what he can offer. There are many more ways to get a good rotary engine than simply going for the high-profile names. (No disrespect intended).

Tom's email address: Tom Wickers ([email protected])

Good luck with your quest.
 
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gyro-3xio

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Diamond United Engines

Diamond United Engines

Diamond Aircraft bought out a rotary engine firm in the U.K. with idea of selling airplanes that use a rotary. Each pack was 50 hp. Their idea was to make a combonation of packs for the hp required. Talk 10 years ago was 4 packs = 200 hp for the 4 seater DA40.
A Katana (or two) was shipped to the U.K. for testing purposes. The project had it's share of problems. One of them namely the high oil consumption.

I'll try to find out what ever happened to the project.

Jim.
 

13brv3

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I love rotary engines, and would really like to see them become a more popular option, but in all the years I've hoped for this, it just doesn't seem to be making that much progress. The only thing that seems to be helping is the availability of redrives, and engine controllers from Tracy Crook. There is also a fellow that makes motor mounts for rotaries, which eliminates another major hurdle. Other products are coming, but not at a high rate of speed, and not in any mass quantities.

The area of rotaries that's been the most frustrating to me is the smaller engines that keep appearing for aircraft use. For some reason, as nice as some of these look on paper, they just never seem to pan out. There really are some nice engines out there, but they just don't seem to be making their way into aircraft in any measurable quantity. With the current Sport Pilot aircraft push, a 100 HP, two rotor engine has the potential to be a 912S killer.

At the moment, one of the best options for a 100 HP rotary is the single rotor based on Mazda parts. This would be a reasonable power/weight option for aircraft that used typical aircraft engines, since the rule of thumb has always been 2 lbs per HP. Unfortunately, if the single rotor is going to be useful as a 912S replacement, it's going to have to go on a diet. There are a number of ways you can save some weight, but what is desperately needed is aluminum end housings, since that would lop about 25 lbs off with one "simple" change. There are at least a few folks working on aluminum housings, but so far, none are ready for use.

Another problem is redrives. I've owned a few of Tracy's drives, and while they work great for the 2 and 3 rotor engines they were designed for, they just don't work well with a single rotor engine, and it's really heavy for this application. The single rotor just has some nasty torque reversals to deal with, and the drive will need a much better torque dampener. Neil's Autoflight drive looks promising, and I think they were going to test one on a single rotor engine, so keep your fingers crossed. Any report on that Neil?

I currently have a single rotor engine that has run, and was mounted on a Kolb Slingshot. I have sold the aircraft, and have decided that I'd like to used this engine on a Dominator. That's the plan anyway, but I have to clear this RV-8 out of my garage first :D

Cheers,
Rusty (the rotary engine wacko)
 

13brv3

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Brent_Brown said:
Try a belt drive on it.? Do you have a web site for the mounts.

Hi Brent,

Atkins was planning to use a belt drive for the single rotor that he sells, and in fact, I even happened to see some parts on the shelf of the guy who was going to build the drive for him. I'm not sure if they ever got it finished or not, and I've never seen it mentioned on Atkins site.

I also talked to a guy who sells belt drives for two rotor engines, and he said that he refused to try to downsize one of his drives for a single. The reasoning was that the power pulse was the same strength as the one on the two rotor, so the drive had to be built just as strong.

I'll get a lot more interested in a redrive when I get time to work on the single rotor project again.

The motor mount guy is Fred Breese who runs Conversion Concepts:
http://www.conversionconcepts.com/

For the sake of completeness, here's Tracy Crook's web page as well:
http://www.rotaryaviation.com/

Cheers,
Rusty
 

WHY

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Hey Rusty

Thanks for the input, did not know about the extra strong pulse reversals on the rotary, I would have guessed this would have been less on a rotary but then that is what suprises are all about. Am looking at one of Niel's autoflight units my self, know he mentioned that he is working on one on a Mazda, I think.

What was the make of that one you have that was on the Kolb Sllingshot? Also what was the hp and do you think the the manufacture is considering a two rotor?

It may be necessary to go two rotor regardless of the hp if the pulse of a single rotor is going t be a problem. For my project I need at least 70 hp to have any good performance. Is that one you have, the one out of Canada that is imported from Germany?

Let's keep in touch, am looking real stro;ng at the Rotomax from Ohio, the single rotor, but did not know about the strong pulse reversal, also the mounting of the re-drive is not go;ing to be easy or neat and the motor originally mounted like a rotax with four bolts closley gathered ot the base.

Tony Stiles
 

WHY

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Hey Duncan

Do you know if Tom Wickers has communicated to any degree with Neil at Autoflight about experimenting with this redrive?

Tony Stiles
 

rtfm

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Hi,
I've spoken to both Tom and to Neil, but I'm not sure if they have spoken much together. What I do know is that Neil seems pretty confident about using his redrive on the Rotary, and Tom uses a redrive on his Cobra Arrow FW aircraft, which use the two-rotor RX-8 engine. I hope to be trialling Tom's single-rotor engine on the Razorback, but I don't know what redrive I'll be using. I suspect Tom will prefer me to use his redrive, so that the entire package can be evaluated properly.

Of course, with the addition of a small turbo charger (and rotary engines just thrive on turbo charging), you can easily boost the single rotor RX-8 to 135HP for almost no weight penalty (ie dispense with some of the silencing gear in the exhaust train).

Regards,
Duncan
PS Give Tom a call. His address is on an earlier post of mine in this thread.
 

13brv3

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Hi Tony,

The engine I have was not commercially produced. I built it using new 93-95 vintage housings, and a 9.7 CR rotor. I did a street port job on the intake and exhaust ports, and had the rotor ceramic coated. The only parts that are not off the shelf stock are the eccentric shaft, tension bolts, oil pan, and counterweights. I got the E-shaft and balance job from "a friend", and that's all I can say about it right now ;)

Rotary engine HP is largely dependent on the RPM you care to turn it. I was personally estimating 110 HP for 8000 RPM. There's almost no way you could get less than 70 HP from stock parts.

As Duncan pointed out, a small turbo will do wonders for the power, and cost nearly nothing in weight since you can leave off the muffler. Turbocharing a Renesis (RX-8) engine is somewhat uncharted territory though. I actually have a small turbo, and was planning to use it, but I already have too much power, so I figured I'd save myself the turbo headaches.

As I mentioned, the redrive is the biggest problem, followed by weight reduction. The torque reversals are not something that can't be fixed, or even ignored to some extent. They will really only be a problem at low RPM, and can be fixed with something as simple as a heavy flywheel. Naturally, that's not the first choice with an already overweight engine though. Better to take care of it with dampeners.

Have you talked to Rotomax? Have they even mentioned a redrive?

Cheers,
Rusty
 

WHY

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Hi Rusty

I have talked to Rotamax and they have been communication with Neil, and are looking into the Autoflite re-drive. There are two main problems that I see with the Rotamax, one it that it is designed to be a generic power plant with the flywheel enclosed on one end with a light weight housing supported with cast standoff's and a tapered shaft coming out of the housing, This does not readily lend itself to monting a red-drive and will require a lot work to do so. The other end has all the accessories, oil pump, 40 amp alt. ect. The water pump is external electric, mounted on the radiator and there is no oil pan so a oil tank is needed, oil is pumped into the bearings and then into the fuel mixture. Power is around 80 hp at I think 7 or 8 k and weight is around 105lbs I think. Fuel mix is between 80 to 1 up to 100 to 1 . They say that both the single 650 cc and the 1300 cc are in production, with the 1300 producing in excess of 160 hp, I'm not sure of the wieght of the 1300 cc but seems like was around 135 lbs.




Tony
 

13brv3

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Brent_Brown said:
what would the flying weigh be of a 13B?

We typically quote a FWF weight of 330 lbs for a two rotor engine. This can vary quite a bit, but probably never below 320 lbs. The bare 13B engine weighs only about 190 lbs, so there's a lot of weight in the redrive, intake, exhaust, radiators, etc.

FWIW, when I had my single rotor complete, using one of Tracy's redrives, the total weight was 240 lbs. The bare engine was only 108 lbs, and the drive was 45 lbs.

For further reference, a 912S that was on the Kolb previously weight 159 lbs complete. That's pretty impressive, and a very nice engine to boot.

Cheers,
Rusty
 

WHY

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The second problem is that the intake manifold is up right and cast onto the housing so any other mounting requires cutting off the intake and welding on what you desire.

Tony
 

13brv3

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Hi Tony,

Thanks for the Rotamax info. At this point, I'm afraid they fall into the "wish them luck, and hope it all works out" category.

There have been a lot of companies that offered smaller rotary engines, but where are they now? Most of the ones that exist now are only interested in selling engines for military contract type drones.

Check out the specs on these guys. It will just eat your heart out that you can't buy one. http://www.uavenginesltd.co.uk/

Rusty
 

WHY

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Hey Rusty

Looked up the web site you listed HISS GROWL HISS GROWL this removes all doubt about the engines application just the availability, not only in experimental , but why not certified. I bet the answer can be given in two words that start with C and L

Tony
 

WHY

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Didn't the gyro world start out with drone engines?

Tony
 

Brent_Brown

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here is the info for th rotamax add 45 pounds for PSRU and oil/water it will 250 pounds. and it should be 140 to 150 hp at 6500 rpm.
Twin Rotor, 1300cc displacement
170 HP @ 7,750 RPM
130 ft-lbs Torque @ 3,700 RPM
153 lbs
(22.7"-L x 17.4"-W x 17.9"-H)
Gasoline carburetor (standard)*
Fuel injection (optional)
Electric starter
CDI Spark ignition
Metered oil lubrication system
40 Amp generator coil (standard)
Specifications for battery, exhaust
and cooling system provided
Metric standard design
 

WHY

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Hey Rusty

Was that e-shaft you got from your "friend" made from a mazda shaft or scratch built?

Tony
 
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