>> I picked up my single rotor 12A project over the weekend and I am
>> interested
>> to know how many guys out there are working on or have single rotor
>> engines.
>> I know most of you are interested in 2 or 3 rotor engines and I do
not
>> want
>> to bog down the list, but I do have some questions if there is
anyone out
>> there with a single rotor engine.
>>
>> I noticed that Richard made reference to his single rotor yesterday
in an
>> email to the list.
>>
>> Jeff LeTempt
>> Dragonfly N41GK
> Yes, Jeff, I had my single rotor running for two years now.
> It is a p-port with compound AL side housings. I had been bogged down
for a
> while with building a house, but I am slowly getting back to it
again now.
> The side housings so far are prof-of-principle configuration,
meaning, not
> flyable. This is going to change next with castings being used,
> accommodating final design features.
> For the 12A based version, the FF weight is 170lb.
> I will certainly try to answer your questions if I can.
>
> Richard Sohn
> N-2071U
> Richard,
>
> Thanks in advance for the help. I know nothing about the history of
the
> engine that I bought. The Ross 3.17:1 PSRU appears to be new and
unused and
> the engine externally looks very nice. It does not have a starter or
> alternator. The water pump housing has been modified with HUGE
anodized
> fittings. It has a thin wall steel tube intake manifold with a Weber
carb.
> No exhaust system. No oil filter or cooler yet. The main pulley is
not
> present on the exposed end of the concentric shaft nor is the water
pump
> pulley. No ignition system, but it does look like there is a later
model
> distributor installed that just has a few wires sticking out (2 or 3 I
> think).
----------------------------------------------------------
You certainly would not need a distributor, since the plugs normally fire
simultanously in AC use.
---------------------------------------------------------------
>
> This engine will go on a tricycle gear Dragonfly that was previously
powered
> by a VW 2180. I would like to have a good solid 80 HP for take-off
and
> climb (would love to have 100 HP). I am more into the economy cruise
any
> will probably typically cruise using about 60'ish HP. I am not all
that
> interested in tweaking every last HP out of the engine, I am way more
> interested in reliability, low maintenance, and longevity. Based on
the
> performance of my MK-IIH Dragonfly powered with a L2000 Limbach I
expect a
> cruise speed of about 140 MHP IAS.
>
> I am considering EFI/EI over the carb and ?? ignition. The Tracy
Crook EC2
> looks very interesting right now. I am very interested to hear your
> recommendations on this. The Crook EC2 might add a few hundred $ to
the
> total cost, but over the life of the airplane that cost is
insignificant.
-----------------------------------------------------------------------
If you are looking for relaiability and low maintenance, I don't think
you can beat a carburetor. All you get with FI is a somewhat better fuel
consumption. There is also no need on the rotary to vary the timing
verus RPM, unless you have a situation where detonation may become an
issue.
--------------------------------------------------------------------
> Do you have to do anything special with counterweights to
>balance the engine?
------------------------------------------------------------------
In priciple yes! Does the engine have a fly wheel or a flexplate?
Standard balancing components from a two rotor will not work! Generally,
the balance weights have to be bigger than on the two rotor. I am using
a 13B counter weight with added weight on it, and a custom flywheel.
----------------------------------------------------------------------
> Not sure what I will use for a radiator or where I will mount it yet.
> Several Dragonfly builders using water cooled engines (Subaru's) have
been
> very happy with a P-51 style scoop on the belly of the fuselage.
With the
> small size of the engine and the long PSRU, I think it would be
possible to
> mount the radiator(s) in the engine cowl. That would almost certainly
> reduce the weight and complexity of the water cooling system.
>
----------------------------------------------------------------------
At the speed the Dragonfly is capable of, cooling should not be a problem.
-----------------------------------------------------------------------
> There is a partial engine mount that looks like it should work quite
well
> and the oil pan looks very good.
>
> I will probably come up with a few hundred more questions - sorry.
If I get
> to be too much of a pest just let me know.
It would help if you could add a picture>
> Thank you very much for your advice!!
>
> Jeff
> Jeffrey.letempt@us.army.mil <mailto:Jeffrey.letempt@us.army.mil>
> Dragonfly MK-IIH N41GK
> Rolla, MO
Vic,
Here is some useful information which will support what I will tell you
about balancing a single rotor.
The heaviest counter weights aren't from the 13B but the 12A, but that's not
a real problem, as adding some weight is possible. I purchased the 12A
weights to see how much heavier they were - it wasn't a cost effective
exercise and GURU use what ever they have to hand and modify them, by adding
weight
Richard Sohn and I don't always agree, but on this particular point we are
singing from the same sheet of paper.
George
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