light twins?

Frank van der Hulst wrote:
Bellsouth News Server wrote:

What would be better than a single, would be a smaller two rotary.


Whatever happened to the motorcycle rotaries? IIRC Suzuki had a 500cc
rotary in a motorcycle about 20 years ago. And Norton too?

I'd guess that a rotary of this size would be ideal for a microlight
aircraft.

They faded into history...

Tony

How much does the 13b single rotor weigh? And how much does it cost to get
the e-shaft shortened?

The basic engine with stock housings is about 120-125 lbs, but you could
lose 25 lbs of that in exchange for around $3000 if Racing Beat ever
finishes their aluminum side housings. The e-shaft can be cut down from a
stock shaft, but it's no small job, so it's better to buy a new one, or find
one that someone else has made. Over the years, lots of these have been
built, including a number of shafts that were made by NASA. In the near
future, there will be a much better availability of these I think, but
nothing definite now.


There is an outfit here in Canada that is promising to produce some small
rotaries for light planes, but I don't know how far along they are. A
German outfit makes single-rotor go-kart engines, as well as an UL
version.

Those are actually the same engine if you're talking about the German place
that I'm thinking of. The Canadian outfit bought the rights to the engine,
and will eventually start making them in Canada, though the price is pretty
high for such an unproven engine. I wish them luck, but haven't seen much
interest from the community yet.

As for other posts on this subject:

There were certainly some smaller rotaries produced, such as the motorcyle,
and even some outboard engines. I just don't think any of those were nearly
as reliable as the Mazda version has been. They also aren't that available,
or I'd love to play with one.

As for rotary engines being in cars, yes, they are. The RX-7 was sold until
2001 or 2002, and the RX-8 has a new version of the rotary called the
Renesis. Excellent engine! In the US, people still remember the seal
problems that Mazda had when they were introduced in the early 70's, which
is unfortunate. Other countries have had several cars, trucks, etc with
rotary engines, but Mazda doesn't sent them here, because we won't buy them.
The RX-7 was discontinued in the US after 95, but sold in other countries
until at least 2001. The RX-8 was said to be our last chance, and if the
sales in the US were good (and they have been), we would get the next
version of the RX-7 as well, and perhaps other rotary powered vehicles.

Cheers,
Rusty

The basic engine with stock housings is about 120-125 lbs,

I meant go make it clear that this is without a redrive, or any other engine
accessories. The total installed weight will be somewhere around 220 lbs
with stock housings, and the currently available (heavy, overbuilt)
redrives. The engine can make 100+ HP pretty easily, and much more with a
turbo.

Rusty

Thanks, for the info, Rusty.

What gearbox are you using? It seems like overkill to put one of Tracy's
boxes -- or something similar -- on a single rotor.

I would think a belt drive might be engineered that would be considerably
lighter -- expecially if you use the poly-v belts.

Just to add about why rotaries aren't more popular -- a big reason is that
the auto industry is geared around the piston engine. The infrastructure of
suppliers and manufacturers is all predicated on that business model, so
there is a lot of inertia there and changing course is like trying to do a
U-turn in an aircraft carrier.

However the wankel engine has some incredible advantages, including
smoothness simplicity, ruggedness and power potential that truly puts it a
class above the piston engine. There is no question about that, as
rotary-powered race cars have proven over and over -- until they are banned
because they simply have an unfair advantage.

Regards,

Gordon.




"Bellsouth News Server" wrote in message
...
The basic engine with stock housings is about 120-125 lbs,

I meant go make it clear that this is without a redrive, or any other
engine accessories. The total installed weight will be somewhere around
220 lbs with stock housings, and the currently available (heavy,
overbuilt) redrives. The engine can make 100+ HP pretty easily, and much
more with a turbo.

Rusty

On Tue, 26 Jul 2005 23:58:12 -0400, "Gordon Arnaut"
wrote:

However the wankel engine has some incredible advantages, including
smoothness simplicity, ruggedness and power potential that truly puts it a
class above the piston engine. There is no question about that, as
rotary-powered race cars have proven over and over -- until they are banned
because they simply have an unfair advantage.

Regards,

Gordon.

It's true that the rotory offers some interesting advantages, one of
which is the ability to continue to run and produce power after the
engine has lost compression due to overheating and warped side seals.

It will make power right to point where you shut it down, but you
won't get it started again because of low compression.

I guessing that it's disadvantages were enough that it never appealed
to big auto makers to work on them. Wankel itself was unable to make
it a success and it's hard to argue that Mazda has either. It's fuel
consumption and inherently dirty emissions which require a lot of
technology to clean up plus the investment in machine tools to create
it just didn't seem worth it to the bean counters, I suppose.

And the public did not seem to care much that it was available. When
Mazda first brought it out, it had a number of quirks that the buying
public had trouble getting used to. It had a cold temperature
starting assist that consisted of an injector that added pure
antifreeze from a seperate tank into the intake manifold. This of
course created a dense white cloud of smoke, which the owner was told
was normal, and it was, but it sure made owners nervous to see it.
And the owner had to refill the tank, which they often did not do,
which resulted in hard cold weather starting. Add this to the manual
choke, which the RX-7's had for many years and which the public had
difficulty using and it's easy to see why it was popular only for a
limited number of people.

Then there was the stench of the exhaust. Nothing smelled worse, not
even a diesel, and you could not tune it away. When properly adjusted
for emissions, it stank most powerfully, it felt like it was actually
burning your nostrils.

Mechanics didn't like it because it had two ignitions called a leading
and trailing ignition and originally, the distributer held three sets
of points in two layers. Not easy to adjust and naturally
problematic.

That of course went away with the advent of electronic ignition, and
eventually the engine was fuel injected and everything was computer
controlled. But converting such an engine for use in an airplane is
not without it's challenges.

Corky Scott

Hi Gordon,

I'm starting out with one of Tracy's RD1C drives, which is 2.85:1, and good
for way more power than I'll make wiht the single rotor. Unfortunately,
it's about 45 lbs stock. Speaking with Tracy, there's probably about 5 lbs
of weight that can be removed without losing any strength, and perhaps more
if you're willing to sacrifice strength in the drive. That wouldn't be a
problem for the single rotor, but if you ever wanted to use it on a two
rotor, it would be.

Richard Sohn has a running 12A single rotor now, and he's using a Hirth G-40
gearbox. At last report, his total engine weight was 170 lbs, which is
pretty great. He's custom made many of the parts on his engine to save
weight, and might produce them if it all works out well. He's currently on
a slow, and careful development and test program, and eventually plans to
put the engine in his Avid, which I believe is flying with a Subaru. It
will be interesting to see how the Hirth box works out, but I'm not sure how
much lighter it really is in the long run. I've asked Richard for the total
weight, but since so much of the adaptation is dependent on his custom end
housings, he hasn't been able to come up with a number. My guess is
something around 30 lbs total for the drive.

I asked about belt drives, and found that someone was making one for the
single rotor that David Atkins is selling. So far, I haven't heard any
reports of how that worked, if it even got finished. One other fellow who
makes belt drives told me that he refused to make such a drive for Atkins,
because it wouldn't be strong enough. His point was that the single rotor
is still full sized, and gives the same strength power pulses as the two
rotor does. Because of this, he felt the drive has to be as strong as the
two rotor drive. This does make sense to me, but I'm sure there has to be a
way to reduce the weight further.

FWIW, my plan was to bolt together off the shelf parts, and see what it
weighs. The Kolb Slingshot that I'll be using initially will handle the
weight, when flown as a single place, and with a BRS chute to balance the
CG. Once I get a worst case weight, then I'll start working on reducing it.

Cheers,
Rusty (hiding rotary info in the light twin thread)


What gearbox are you using? It seems like overkill to put one of Tracy's
boxes -- or something similar -- on a single rotor.

I would think a belt drive might be engineered that would be considerably
lighter -- expecially if you use the poly-v belts.

Saying that Rotaries have an unfair advantage is only part of the
story. In the appropriate classes, they were raced for years, often
successfuly. But they were still hated because they were so LOUD.
Unbearably, explosively loud without big heavy mufflers - which got to
be mandatory in many venues This might not matter much for a target
drone or a tiny cart engine but it does everywhere else.

Saying that Rotaries have an unfair advantage is only part of the
story. In the appropriate classes, they were raced for years, often
successfuly. But they were still hated because they were so LOUD.
Unbearably, explosively loud without big heavy mufflers - which got to
be mandatory in many venues This might not matter much for a target
drone or a tiny cart engine but it does everywhere else.

I guessing that it's disadvantages were enough that it never appealed
to big auto makers to work on them. Wankel itself was unable to make
it a success and it's hard to argue that Mazda has either.

How can you say that Mazda hasn't made this successful? Sure, the initial
introduction had it's share of problems, but since the RX-7 made the
re-introduction of the rotary here in the US, the engine has been as
troublefree as any engine produced. Emissions was one of the biggest
problems, but the newly redesigned Renesis engine cleaned that up, as well
as taming a bit of the bark, and overly hot exhaust. Fuel consumption in
aircraft use does not seem to be any worse than any other engine of the same
power range. The truth is that other manufacturers tried the rotary, but
didn't feel like it was worth developing, since they were perfectly happy to
churn out piston engines. Only Mazda seems to have had the willingness to
stick with it, and make it successful.

But converting such an engine for use in an airplane is
not without it's challenges.

Corky Scott

What challenges does it present, that aren't shared by any other auto
engine? Heck, it already has dual ignition. These days, two rotor engines
are not nearly the challenge that some engines would be, because Tracy Crook
sells engine controllers, monitors, and gear drives. Conversion Concepts
makes excellent mounts. About the only thing missing is an off the shelf
intake, and exhaust, which aren't far behind.

Cheers,
Rusty
13B powered RV-3 flying (2500+ fpm climb, 200 mph cruise)
Kolb Slingshot being converted from 912S to single rotor almost as I type

Earlier, Bellsouth News Server wrote:

How can you say that Mazda hasn't made
this successful? Sure, the initial
introduction had it's share of problems,
but since the RX-7 made the re-
introduction of the rotary here in the
US, the engine has been as troublefree
as any engine produced.

Well, Corky didn't say that Mazda hasn't made the Wankel rotary a
success. He only said that it's hard to argue it:

Earlier, Corky Scott wrote:

: Wankel itself was unable to make it a
: success and it's hard to argue that
: Mazda has either.

That the vast majority of Mazda cars are powered by conventional piston
engines supports Corky, at least when you consider the aspect of
commercial success. And it is undeniably commercial success by which
car manufacturers measure themselves and each other. Sure, the RX-7 and
RX-8 motors seem to be trouble-free, but at what cost?

And further, since most of the patents that cover the Wankel
innovations are now expired or are about to expire, you'd expect to see
other manufacturers adopting the Wankel. That you don't see this tends
to support Corky's argument that for the vast majority of engine
applications the Wankel's disadvantages outweigh its advantages.

Personally, I think that Wankel rotaries continue to be part of Mazda's
automobile offerings only because it would be harder sell an RX-series
car without them. I believe that Mazda decided to continue the Wankel
heritage of the RX only after carefully balancing the greater cost per
unit horsepower of their rotary against the whizz-bang (Okay,
whizz-hummm in this case) technical appeal in the RX package. An RX
without a rotary would be like a Mustang without three-element
taillights or a Buick without fake exhaust portholes.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com/hp-24