>> Hi
>>     Try this site,engine and redrive all new
>>                                        Regards Ray
>>   http://www.tomair.com.au/
>>
>>
>> These guys are in the early stage of development.
>> Mostly hype and little substance. Some ridicules claims
>> in the past. The web site is vague about a lot of things.
>>
>> So far their engineering leaves a lot to be desired.
>> Attaching a two rotor to  Hirth gear box is doomed to failure.
>>
>> I wish them well but I will keep my money firmly in my pocket
>> for awhile and see what happens.
>>
>> Paul Lamar ...No rotor no motor.
>
>
>
> Paul,
> I wish them all the best, and I don't like to see Aviation endeavors > fail,
> especially if their Aussies, but I'm yet to see +ve outcomes.  The last > I
> heard they were having cooling problems - funny that!
>
> BTW their using your favorite flat plate mount.
> I wondered what gearbox they were using, I did ask someone and all they > said
> was they were off-set.
> George ( down under)


I've attached some pictures of  the Cobra "Viper" engine and radiator
installation in the Cobra "Arrow" aircraft.  It looks like a spur gear
drive.  I could not find these pictures on their current web site.  I
don't remember where I acquired them.  The web site says this aircraft
crashed on landing;  there was no mention of dates.

Aubrey

Looks like a plastic or wood mock up to me. Perhaps the metal
looking parts have been scrounged from wherever.
Could be a stock manual tx bell housing painted black.
That is no SAE prop flange.

Like the dozen or so other PSRU's I have seen depends on what
the inside looks like.

Paul Lamar ...No rotor no motor.


---------------------------------------

I read with interest the thread about the rotary engine from cobra
Aviation. The engine is far from a mock up and in fact has been in a
test aircraft for some time. Unfortunately that aircraft came to grief
on landing about a week ago ( no, not airframe or engine related ).
Like all developments there has been teething troubles including cooling
which have been addressed and I am sure there will be others to raise
their heads but presently the engine is performing well. I also agree
that in the early stages there were some ridiculous statements made but
once cutting through the crap to the reality the performance including
cooling has been good. The PSRU is from NZ and runs a 3 blade in flight
adjustable 70" prop. the ECU is a Wolf 3D and individual Bosch coils
supply the spark.

As far as the engineering goes, I have seen some pretty ordinary
fabrications on this site from time to time and this is as good as most.
I am including a few pics of the engine on my project which I expect to
have flying within 3 months time.

Your site has been of great assistance to me by giving me a much greater
understanding of the Rotary but I don't believe its fair to knock
something just because it is different from what you do.

Baz Mayne

--------------------------------------------------

I never said the engine was a mock up. I said the gear box "Looks like a
plastic or wood mock up to me." The subject of the previous message
was gear box.

It is not because it is different. When the designer makes ridicules claims
his engineering ability is immediately brought into question.

Engineering and fabrications are two entirely different things.
The welding and paint job on a poorly designed motor mount can be
perfect but that does not make it a good or safe motor mount. The strut
holding the lower end of the oil cooler is going to crack and fall off.
An obvious example of incompetent engineering.

From the looks of it the engine is too big and heavy for the airframe.

Your cooling problems are just beginning despite the nice looking
oil cooler. Have you tested that oil cooler to 300 psi?

And of course the gear box is a total unknown.

Why aren't you asking for help?  It's free and nobody is twisting
your arm to implement it.

To be brutally frank I don't mind anybody killing themselves
but I wish they would do it in something other than
a rotary powered airplane.

Paul Lamar

Hi Paul
I went to Melbourne to the Cobra factory before purchasing my RV7 kit. I was
impressed with the Cobra airframe but you are right that the Mazda engine is
far too big for it. Tom explained that the power would be held down to 135hp
but even so I predicted that cooling, under hood heat, and exhaust noise
would be major problems.

Ian Beadle Australia. Mounting engine tomorrow.

G'day Paul,sorry if I misunderstood what you were referring to with the mock
up.
I take on board your comments on the oil cooler lower mount and that is
something I may have to look at. No I haven't pressure tested the oil
cooler, it is the same as that used on some V8 supercar race cars down here
in Oz and if it can stand that it should be fine for this application.
I'm sure that once running I will have a lot of questions and requests for
advice, as for the cooling, I have a few ideas to try when the time comes

Baz Mayne

You need a couple more struts stabilizing that lower oil cooler
mount. Also the rotary engine oil pressure can be up to 150 psi when
the oil is still cool and you run the engine up for takeoff.
Much much higher than an piston engine.
That oil cooler has large tanks that will deform when
pressurized and might crack and leak. To be on the safe
side... test pressurize it to 300 psi. You don't want your
precious bodily fluids pumped over board in a matter
of seconds or worse start an in flight fire.

It is best to plan things out in advance before you start
making parts. Either with a full scale mock up or a 3D cad
program.

Also the plate between the engine and the oil pan
is too thin. It might crack just inboard of the front motor
mounts. The front motor mounts are taking 90% of the vertical load.

I see the motor mount itself has been kludged but I
see no  serious problems with it at this time. It would
be better to start over on the motor mount but not
mandatory. If you do use a wide Schertz beam the second time
around and you will have more room for a better exhaust
manifold.

From the looks of it there is no room under the cowl
for an adequate duct or diffuser to feed the water radiator.
You might have to move the rad back to the aft fuselage
which is a whole new can of worms.

The plastic header tanks on the radiator should be done
away with as they too are prone to cracking and leaking.
Have aluminum tanks tig welded and use silicone rubber hose
and constant torque hose clamps. Black hose and
and cheap worm drive hose clamps are not adequate.

Make sure you have good beads on all those sections
of aluminum tubing in the water plumbing. The cooling
system can build pressure to as high as 30 psi which
will apply a separating force to the hose and joint
of about 50 pounds.

The rotary engine itself is never the problem. What causes
crashes is plumbing plumbing and details details.

Paul Lamar ...No rotor no motor.

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