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Author Topic: Rotary Valve 4 Stroke Engines  (Read 1048 times)

Offline Bob Zambelli

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Rotary Valve 4 Stroke Engines
« on: August 03, 2006, 11:32:17 AM »
While collecting my thoughts on more 4S info that I might post, I remembered two unique engines that I have.

They are both 4 stroke but have rotary valves. ??? ??? ???

One is an HP .26 with an overhead drum valve that is gear driven, spinning on the same axis as the cylinder.

The other is a Webra .60 with an overhead drum valve that is belt driven, spinning on an axis parallel to the crankshaft.

I have not run  these engines. Have any of you tried them for C/L? I know that Ted Heinritz experimented a few years back with the HP.

By the way, these are not to be confused with the RCV engines presently offered on the RC market.  n1 They're a whole different concept.

Bob Z.


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Offline dennis lipsett

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Re: Rotary Valve 4 Stroke Engines
« Reply #1 on: August 03, 2006, 01:13:03 PM »
Bob,
I never used one in C/L but I will say that the 21[pre 26] was a gutless wonder
It barely flew most planes designed for a 20/25 sized motor.They are not the worlds best hand starter either, I'm really good and I had to use a starter on too many occassions. The 49 was a non issue and has stayed in it's box. Oh and they are incredably heavy for their displacement. Cost is too far in excess of their usefullness. The engine is not noted for it's torque or it's ability to use a large variety of props
A benchmark of an engines usefulness is how many are in service. This motor doesn't exist in the modelling community.
On the plus side it has a neat almost electric sound as it runs, has a truely efficient carb, and is the most fuel efficient little 4 stroke that you'll ever own. I cant remember the fuel consumption figures but it was astounding in it's ability to barely sip fuel..
My opinion is it's nice to look at but thats about it.

Dennis

Additional info,
The 21 and  probably the 26 came with a plug with a much thicker gasket. You must be careful changing plugs, you can have the plug touch the rotor, obviously not a good thing.
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Offline Bob Zambelli

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Re: Rotary Valve 4 Stroke Engines
« Reply #2 on: August 03, 2006, 01:58:54 PM »
Dennis - Now that you mention economy, I recall Ted's Ringmaster flying near forever on 3 ounces. And yes, I don't recall and stunning performance. ''
Maybe it needs gobs of nitro???? j1
Lotsa pitch?
Or just use it for outboard weight!!! ;D

Bob Z.
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Offline rustler

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Re: Rotary Valve 4 Stroke Engines
« Reply #3 on: August 03, 2006, 02:02:32 PM »
I general, power is proportional to fuel consumption. Usually low power = low fuel consumption.
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Ian Russell.
[I can remember the schedule o.k., the problem is remembering what was the last manoeuvre I just flew!].

Offline Randy Powell

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Re: Rotary Valve 4 Stroke Engines
« Reply #4 on: August 03, 2006, 10:54:26 PM »
I used an RCV in a plane a couple of years ago. Most frustrating engine I ever had. Ran great and had all the torque in the world. Couldn't believe it would just trundle over the top in a wingover. I kept thinking the plane was just going to fall in on me, but it just thudded over the top without a problem. Didn't care much about wind. Seemed to just plow through the wind. I loved that engine and it was fabulous...for about 20 flights. Then the gear between the rotating cylinder and the crank skipped. I didn't know that's what happened at the time. The thing still started fine but wouldn't run evenly with the rpm jumping all over the place and suddenly had all the power of a Fox 35. I sent it back to RCV to be repaired. They did and sent it back...where it ran absolutely great for another 20 flight when the gear jumped again. I took it apart and reset it. Put it back together and it ran great again...for about 5 flights before the gear skipped again.

Turns out the tolerances weren't all that great and I was using what was too big a prop according the the service rep I talked to (a 13x5 RevUp). Too much torque on the crank caused the gear to skip. The crank just had too much fore and aft play and any torque on the crank caused the gear to skip.

So, great engine with marginal reliability in this application. I'm told that they run forever in RC, but I sure couldn't get it to quit gear thrasing even using smaller props, so I eventually gave up. It's now sitting in the drawer in pieces.
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Offline dennis lipsett

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Re: Rotary Valve 4 Stroke Engines
« Reply #5 on: August 05, 2006, 06:33:59 AM »
Quote from: Bob Zambelli on August 03, 2006, 01:58:54 PM
Dennis - Now that you mention economy, I recall Ted's Ringmaster flying near forever on 3 ounces. And yes, I don't recall and stunning performance. ''
Maybe it needs gobs of nitro???? j1
Lotsa pitch?
Or just use it for outboard weight!!! ;D

Bob Z.

Bob, I've run 30% through the thing but the timing is as Ian says quite mild, incidentally the Webra T4 91 is no world beater either, I own that one also. No rotar or aspen valve 4 cycle or overhead cam as the Abatar or Conley has impressed me very much. I've owned just about all of the 4's since the first OS in 1976 to  about 1995. I've pretty much lost interest in them and find that good 2 cycles are much more versatile for my purposes.
However I do hold a real soft spot for the Enya 34/40 open rocker motors and the Kalt 45.A real jewel of a motor. Stone reliable amnd the power was considerably better then the OS offerings of the period.
Dennis      ;D    ::)
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