Engines > Your Own Design

The Le Rhone 9C

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Craig DeShong:
Ever since I finished my last Otto & Langen model, Iíve been trying to choose my next project.  I had several in mind, but nothing really immediately inspired me.

I have been fascinated with WWI rotary engines (where the crankshaft is bolted to the airframe, and the whole engine rotates with the propeller) since I was a child.   Probably every American kid of my generation was introduced to Baron Von Richthofen, the ďbloody Red Baronď and his Fokker Triplane (powered by a Le Rhone) through the immemorial Carl Shulz and his peanuts comic strip with, Snoopy flying his doghouse as a Sopwith Camel (also powered by a Le Rhone) and constantly being shot down by the Baron and his Triplane.

I started some research on the Le Rhone, the rotary engine that powered 80 percent of the WWI aircraft.  The reading was fascinating and before long I was hooked on building a model of the Le Rhone.  So we all know the engine Iím planning to model, below are a few photos of an original engine.

And this is a youtube video of one being started and run at the NW Biplane Fly-In 2009, Felts Field, Spokane Washington. 

The Le Rhone came in various models, with the 80 HP 9C being the most widely built during the war.  I personally think it is the most attractive of the different versions, with the intake pipes out in front of the cylinders where with other versions (such as the 9J) they are positioned behind the cylinders.

Lest you be misled; Iím not trying to attempt a model such as the exceptional radial engines that Mike has built.  His work is just fantastic and I wonít begin to compare what Iím trying to accomplish to what heís done.  As Iíve built in the past, this will be a ďsort-of-scaleĒ model of the Le Rhone.  None of my scale models will pass close scrutiny, but they look pretty accurate from a few feet away.  That was the plan I had as I began design of the Le Rhone. 

As I got into the design I began to realize that an awful lot of stuff whirls around inside the engine case and getting it all to fit, let alone preserve the needed clearances was going to be  difficult.  This became so problematic that as the design progressed, I started doubting my skills in building something as complicated as the design was becoming.  Reluctantly I decided to switch my efforts to designing a free-lance rotary engine with five cylinders.  With a free-lance design you arenít held to any specific dimensions, and if something needs to get bigger or move, youíre free to do so.  The design of the 5-cylinder rotary was well under way; but the more I looked at it the more dissatisfied I became.  Realizing that I couldnít really get excited building this free-lance engine, I took another hard look at the Le Rhone.

This current design has been worked, and re-worked, and modified countless times until I think I have everything inside the scale size engine case with the clearances needed and Iím thinking I have a good shot at being successful with the build of this model.

The model will be a bit under Ĺ scale; being a bit short of 18 inches across the diameter of the cylinders, valve rocker to valve rocker.  Itís a bit larger than I wanted but if I build it smaller, the parts get so dang small that I wonít be able to see what Iím doing and then building stops being fun and why build if you arenít having fun?

Donít expect this model to be built quickly, Iím through with spending eight hours a day, seven days a week in the shop, so the build pace will be at a much more leisure pace than in the past.

Before I leave you, Iíll give you a few views of the design from my CAD software. 

Wow, that's an amazing project, pure scale or not!  The shop elves are lining up thier little rocking chairs next to mine in front of the screen to watch along.   :popcorn: :popcorn: :popcorn:

it will be fun to watch this build!  :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:

Wow, Craig, I am going to enjoy watching this one come to life.  :popcorn: :popcorn:

This is going to be a big engine, 18 inches across. Have you calculated the displacement? It will surprise you. It's also going to need a big propeller as well, so I hope you are good with the brown stuff.

Where are you going to start? I usually tackle the cylinder heads and cylinders first. You can get into a nice rhythm with nine of everything.

Remember; Real engines are round


I'm looking forward to following this one also. Don't forget to lay in a supply of authentic castor oil for 1st start day! Supposedly WW1 fighter pilots rarely had to worry about constipation.


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