Hi Guys,
I have been looking at various engine options for nitro or gas powered UAVs. One of the issues mentioned for all fuel powered engines is the vibration. Here is engine that has caught my interest for some time but would like to get feed back from any one who has used this engine. I am particularly interested in knowing the vibration it generates , is it same as regular nitro engine or more or less?
here is link
http://www.rcvengines.com/rcv90sp.htm
http://www.rcvengines.com/images/90sp.jpg

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Morli,

Wow, I've never seen one before!

But after looking at the diagrams a while I don't see why it would have any less vibration. It just looks like the axis of vibration would be changed.
Hi Doug,
The axis of piston movements is what started me thinking. I do remember reading( or may be I am imagining ) some where about the vibration in single and multi cylinder traditional IC engines and how it in some advance physics explanations( which went over my head) is very difficult to eliminate. If prop is well balanced , I feel that this engine might be generating less vibrations or atleast the vibrations are in manageable direction,
What do you think will be result of change in the axis of vibration? What other advantage do you think this engine has( forgetting the sales pitch in the website) ?
other than that I am wondering about torque twist( do we need any offset on firewall like normal engine?)I can almost think of this as poor man's rotary engine :). i wish there are any rotary engines are available in this price range :(
Torque twist is due to 2 things :
-The plane wants to rotate in the direction opposite of the propeller (Newton's action reaction law)
-The airflow generated by a propeller corkscrews it's way backwards around the fuselage and it hits one side of the rudder with a certain force, creating unwanted yaw. It must be counter-acted when applying full throttle.
Other than it's radically different design, an RCV engine behaves like any other Nitro engine.
It is not immune to Newton's law, or to prop wash.
The only way to get rid of prop wash and torque is counter rotating propellers on the same axis like seen on the Russian Tupolev Bear Bomber and some US Navy warbirds.
Maybe a Wankel?

In a Mazda, they are smooth as can be, never used an RC version though...

http://www.osengines.com/engines/osmg1401.html

I've got a 120. The torque is twice a traditional IC engine due to gearing and requires careful mounting so the bolts can't rip through the firewall. Also the company advises not to use rubber damper mountings as I guess these can increase the torque effects/break off.
The best ever contra rotating plane ever IMHO is this one( found it few years back) by Mr.Bugatti model 100p , Thanks for the explanation Olivier. and that is why I am looking at RCV hopeing it might take care of Mr. Newton to some extent.

I can't do much about Mr.Newton and his 3rd law except with firewall offset, however for the second issue ( airflow corkscrew), I like to use pusher config which should take care of it. :) I thought of using contra rotating props in pusher config but it is beyond my means and ability for now.
thanks Whooper for the tip on wankel , the price of these beauties have put me off for many years and so have been searching for different designs, RCV is what I found 2-3 years back and am wondering the pro and con ever since.
One more of gr8 idea/comcept is here
If anybody is interested here is a link to some contra-rotating electric motors

@ Condor,
Wow, Thanks for the link, gives me some ideas , does this one need spl ESC with 6 pin out?

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