>
> Paul,
>
> On a previous post, I think you said that 20B engines are getting
> scarce and expensive.  What is unique about them besides the crank?
> Can you build a three rotor with 13B parts if you have a crank made?  I
> noticed that Racing Beat offers a unique 20B end piece made out of
> aluminum.  I think a three-rotor with aluminum end and intermediate
> housings would be ideal for this helicopter:
>  http://www.vertical-aviation.com/
>
> By the way, did you get a chance to go through that website on the
> Cessna CH-1 helicopter?  It uses an engine installation that would make
> an automotive based engine simple to install and it has a very elegantly
> simple rotor head.
>
> Steve Brazil
>
> Please don't send html messages. It screws things up down the road.
>
> The 3 rotor intermediate housing is unique as well as the shaft.
> The Aussie have a special 3 rotor shaft and center main bearings
> so 13B intermediate housings can be used to build 3 or four rotor
> engines. You can also buy a 3 rotor from Mistral as they are making
> all the parts.
>
> I read the site but I saw little on the rotor head or dwgs of the rotor
> head.
>
> --
> Paul Lamar ...No rotor no motor.
>


What is that "Aussie" company?  Most of what I see about Mistral is that
their stuff is very pricey.

On that CH-1 website, the end of the piece has a flight report as well as
exploded diagrams of the rotor head and control mechanism.  It is a
teetering, free coning type but it is not underslung.  It uses bent-up
L-sections made of stainless sheet metal; there are no feathering bearings.
Very clever.

Steve Brazil

I think their web sites are down right at the moment.
http://www.xtremerotaries.com/
http://www.gurumotorsports.com/


Yes I saw that dwg but I did not understand it at first. Are they twisting
that bent up sheet metal to change the pitch? Scary.

Too bad there are no good pictures of the rotor head.

Paul Lamar ...No rotor no motor.

------------------------------------------------
You can get the info you want/need from this URL, even though the
main site maybe not be available this is some of the older pages.

http://www.xtremerotaries.com/main2.htm

Regards David



Actually, those flexing L-brackets should be capable of unlimited life.  You
have to remember that the pitch range on a helicopter is actually fairly
small, probably no more than ten degrees.  This fact is also why the Kaman
system works.  Also, the use of steel straps to handle the centrifugal loads
on rotors is fairly common and it works well.  The only problem they had
with the CH-1 was on start-up, the horizontal leg of that "L" would try to
buckle to they put a little strut in there to control that.

On this VTOL you guys are talking about, you are probably going to need
about 40 degrees of pitch change available so I think there is no way to not
use roller element bearings for feathering.

Steve



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