|
Post by planeimages on Aug 10, 2006 21:40:55 GMT 12
Tonight's star prize for a beautiful lounge suite. (Monty Python)
The Bristol Boxkite (and I assume the Farman biplane from which it was copied/stolen/licenced- delete whichever does not apply) had a Gnôme rotary engine located behind the pilot and passenger.
What was peculiar, and possibly unique, about the engine installation?
|
|
|
Post by turboNZ on Aug 10, 2006 21:44:52 GMT 12
Ahh,...I know this...... The engine was a pusher, but the rotary cylinders were BEHIND the propellor (ie in the prop-stream). Weird but worked.
I remember seeing the replica on that cool BBC TV show "Wings" in the 70's.
|
|
|
Post by planeimages on Aug 10, 2006 22:09:54 GMT 12
Gee, there's no stopping you Sir. Well spotted. Very understandable when you think about it. The Gnôme Omega's crankshaft protruded from both ends of the crankcase. I guess it was a relatively simple matter to connect to prop to either end of the case and, similarly, the crank to the airframe. Some, if not all, Blériots used the Gnôme which had the prop in front and the rotary mounted by the back end of the crank.
So how am I going to make my proposed 1/4-scale, R/C replica, powered by an OS FT160 horizontally-opposed twin be authentic in this regard? Methinks I'll just act dumb and hope that there aren't any nerds about.
Yes, I know, I could use the FR 5 cylinder radial but it would be too big for this scale. If I go any bigger I might as well build to full scale.
|
|
|
Post by planeimages on Aug 10, 2006 22:13:52 GMT 12
Did the three replicas built for the film "Those magnificant men... " use radials and hang the prop out the back? I guess I will find out when I see one of them at Oakey Museum (Qld) in October.
|
|
|
Post by planeimages on Aug 10, 2006 22:16:46 GMT 12
Yep, They cheated. I just found a pic of the Shuttleworth copy in flight and the prop is at the back.
|
|
|
Post by turboNZ on Aug 10, 2006 22:33:38 GMT 12
I remember seeing a pic of the Boxkite quite a long time ago and thought that is a weird way to do an engine. Funny how you remember those obscure things.
The problem you have is if you spin the cylinders as well as the prop on the twin you have (even in 1/4 scale) some significant forces acting on the airframe as well as major stresses to a crank which isn't designed for that sort of torque.
Can you get R/C scale rotaries? If so, I would imagine they would be a real nightmare to operate.
|
|
|
Post by planeimages on Aug 11, 2006 19:02:42 GMT 12
The modern model aircraft four-strokes turn the crank and hold the cylinders stationary.
OS make a very wide range of 2-strokes and four-strokes (with valves and rockers).
They also make several horizontally-opposed twins then double this up as a flat four. VW/Lycoming, etc. style.
Then they make a 5 cylinder radial (not rotary). This and the bigger flat twin put out 4 hp.
Incredibly they also make a Wankel Rotary (steady there you in the back) not that kind of wankle. This might have a fiar bit of gyroscopic precession effect.
These suffer from poor cooling so I am told. This is evident in the design as it is difficult to arrange sufficient fins.
Check out OS's website. Type in OS model aeroplane engines.
|
|