Author Topic: The Le Rhone 9C  (Read 24439 times)

Offline Craig DeShong

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The Le Rhone 9C
« on: September 05, 2021, 08:10:37 PM »
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. 






Craig
The destination motivates us toward excellence, the journey entertains us, and along the way we meet so many interesting people.

Offline crueby

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Re: The Le Rhone 9C
« Reply #1 on: September 05, 2021, 08:31:25 PM »
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:

Offline cnr6400

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Re: The Le Rhone 9C
« Reply #2 on: September 05, 2021, 08:51:28 PM »
it will be fun to watch this build!  :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:

Online Vixen

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Re: The Le Rhone 9C
« Reply #3 on: September 05, 2021, 08:53:02 PM »
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

Mike
It is the journey that matters, not the destination

Oh! sod the journey, lets hit the bar and pool instead.

Offline RReid

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Re: The Le Rhone 9C
« Reply #4 on: September 05, 2021, 09:23:37 PM »
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.
Regards,
Ron

Online Jo

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Re: The Le Rhone 9C
« Reply #5 on: September 05, 2021, 09:34:26 PM »
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. 

I assume the tricky bit you refer to is the slipper arrangement on the master rod and the three concentric grooves. You could "cheat" and reused the mechanism used on the Chenery Gnome rather than be mechanically true to type inside the crankcase  :-X

...just an idea  ;)

Jo

Enjoyment is more important than achievement.

Offline RReid

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Re: The Le Rhone 9C
« Reply #6 on: September 05, 2021, 09:36:41 PM »
By the way, if you want to make the long drive to Bethel, Pennsylvania, the Golden Age Air Museum there has an accurate, scratchbuilt, DR-1 flying behind an authentic Le Rhone rotary engine (I don't actually know for a fact that it is a Le Rhone). Lot's of other cool stuff there as well, and they put on really fun airshows. Kinda like Old Rhinebeck, only different.
https://www.goldenageair.org/collection/1918_fokker_dr_i_triplane.htm
« Last Edit: September 05, 2021, 10:18:45 PM by RReid »
Regards,
Ron

Offline Elam Works

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Re: The Le Rhone 9C
« Reply #7 on: September 06, 2021, 01:11:02 AM »
I hate to be the one to point it out, but the intake pipes on the 80hp LeRhŰne 9C are on the trailing side of the cylinder. Rotaries had the exhaust on the leading side maximize cooling of the hottest bits of the cylinder heads. In the case of the 80hp LeRhŰne, things are rather more fortunate than its contemporaries as there are drawings of most all of the components as it was built under license by Union Switch & Signal in Swissvale, PA. Some of the drawings (photocopies) are very difficult to read, but in most cases the dimensions can be figured out from the mating component drawing. It does save a lot of experimentation and guesswork of proportioning the parts so they all fit together. Of course you might still simplify it dramatically just to make it easier to build. I got most of the way with my CAD model, less the rocker and valve gear before running out of steam.

The situation is almost as good with the 110hp LeRhŰne 9Jb, with most of the drawings available. The first pics in your post are of the 110hp, which had the intake pipes on the rear side of the crankcase. I did not get as far with that so not entirely sure what is missing in the drawing package until you go to look for something and find it is not there. Most other engines you end up scaling a cross section view from a handbook. Though in the case of the Clerget 9B I was able to borrow an original Gwynne built version, disassemble, clean, and reverse engineer it in the process. And if you have a British built Clerget 9B you have a third of the Bentley BR1. Not to be confused with the slightly bigger Bentley BR2 popularized by Lew Blackmore's serialization in Model Engineer and publication as a book.

-Doug

Offline steamer

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Re: The Le Rhone 9C
« Reply #8 on: September 06, 2021, 09:06:34 AM »
I'll be watching this one take shape!   The design work is a huge part of building from scratch, I can attest to that!
18" is a big engine....this one can hurt you!....Like Mike said, it can surprise you just how big they are....

I'm really looking forward to the build on this one!  Get on with your good self sir!

Dave :popcornsmall:
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Damned ijjit!

Offline Craig DeShong

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Re: The Le Rhone 9C
« Reply #9 on: September 06, 2021, 07:41:06 PM »
Thanks for all the interest.  Iíll attempt to answer or recognize all the responses/questions.

Chris and CNR- great to have you along!

Mike: donít know what I was smokíin yesterday.  The scale is actually much closer to 1/3rd size than Ĺ.  The distance across the cylinders (rocker to rocker) is a tad over 12 inches (not 18??).  One of the places where Iím deviating from the full-size engine is in the area of the cylinder head.  The full size has blind cylinders with the valve guides set into the end of the cylinder (head).   Iím not looking forward to boring out a blind cylinder and then reaching in about 3 Ĺ inches to cut valve seats and expecting to have much success, accuracy and a smooth valve seat is paramount; therefore Iíve designed the heads to be separate and Iíve decreased the bore of the cylinder so I can bring cap screws up from the bottom of the cylinder to Ďblindlyí attach the head.  This should give the appearance of the head and cylinder being one integral unit on the model when in-fact they are not.  In order to do this I needed to thicken the head so that it can accept the threaded ends of the bolts and an attentive observer will recognize this in the model.
The bore/stroke of the full-size is 4.13 x 5.51 inches.  The bore/stroke of the model will be 1.125 x 1.425 inches.  You can see that Iíve shortened the stroke (to get things to fit in the engine case) and decreased the bore (to accommodate the fasteners for the heads).  The model will have close to 9 cubic inches of displacement so I doubt the decreased bore will be a concern in allowing the engine to run.  Iíll probably need to use a smaller propeller.

I thought Iíd start with the engine case, and assemble the engine as I go.

Ron: "old hat" for you I'm sure, but for others.... The Germans thought so highly of the Le Rhone that they acquired a few from downed allied aircfraft, dis-assembled the engines, and reverse engineered their version; the Oberursel U.R II.  These engines were not considered as reliable as the Le Rhone, but further investigation seems to point to the oil being used.  The Le Rhone and its clones operate on a total loss oil system, where the oil was injected into the engine, and then lost through centrifugal force through the many orifices in the engine case.  The Allies had access to castor oil which was used as the lubricant; the Germans did not have access to castor oil, so they used an inferior oil, thus the increased incidents of failure of the Oberursel. 
With a total loss oil system, this is a messy engine with oil being flung out in a 360 degree circle around the cylinders and blown back through the prop wash.  Even though many of the airplanes had cowling over the engine the pilots still became covered with castor oil, having to occasionally remove their goggles and wipe them clean.  This also resulted in ingestion of a certain amount of the oil and we can understand why a pilot might be compelled to hurry back to the airdrome after a mission.  :toilet_claw:

On another note: I was up at the Rough and Tumble show in Kinzer, Pa. with my four Otto & Langen models a few weeks ago.  They put me up in the Willock building and I was right across the aisle from the three full size Otto & Langen engines they have on exhibit (two of which Iíve modeled) I had a great time.  I was also a hop, skip, and jump away from Bethel, Pa.  I would have stopped by had I realized.

Jo: One of the engineering aspects of this engine is the slipper rings.  I had to draw this up in my CAD system to actually see these things in operation.  For those who donít knowÖ where most radial/rotary engines have a master connecting rod with all other slave connecting rods attached to a disk on the main rod with a bolt; the Le Rhone is different.  It has no master connecting rod, but rather a disk on the crankshaft with concentric groves cut into it.  Each connecting rod is connected to the disk with ďslippersĒ that fit the groves in the disk.  The nine connecting rod slippers have convex ends that can slide back and forth in the disk groves as required as the engine case revolves.  They donít slide much, probably less than ten to fifteen degrees but they do slip in the groves.  Iím going to attempt to model this.  This will take some very close tolerance fitting so the engine doesnít have a lot of ďrod knocksĒ when it runs.  Iím eager to give this a go.

The slipper rings are certainly an issue, but the real problem was fitting the intake and exhaust cams, the cam rockers, and the gearing that drives the cams inside a scale size engine case.  I canít make a ring-gear in my shop as the full size uses to drive the cam disks, so Iím stuck with spur gearing.  With a little ďfinaglingĒ I managed to squeeze everything in.

Doug:   :-[
Sometimes you get so deep into the forest that you canít see the trees.  I have no excuse, but Iím sure glad you caught this.  Iíd have made a scale model of a ďnothingĒ had you not pointed this out.  THANKS!

Finally, Dave:  Glad to have you along!

So, letís try this againÖ. A few photos of the Le Rhone 9C




Iíve revised the CAD drawing.  Fortunately, the required changes didnít cause too much of a fuss inside the engine case, and in-fact the re-positioning of a few components might have helped a bit.






« Last Edit: October 07, 2021, 01:11:06 AM by Craig DeShong »
Craig
The destination motivates us toward excellence, the journey entertains us, and along the way we meet so many interesting people.

Offline steamer

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Re: The Le Rhone 9C
« Reply #10 on: September 06, 2021, 07:57:47 PM »
This is going to be good!

 :cheers:

Dave
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Damned ijjit!

Online Vixen

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Re: The Le Rhone 9C
« Reply #11 on: September 06, 2021, 09:04:01 PM »
Hello Craig,

A 150 cc, 12inch diameter, 1/3 scale model, based on the Le Rhone 9C engine will still be an impressive engine. !/3 scale is a nice size, the components are big enough to be worked on normal model engineers equipment and avoids the need for watchmakers skills (and eyesight). You have made a sensible decision to have detachable heads and separate cylinders, that will make the model so much easier to make.

You have to admire the engineering that went into these engines at the turn of the last century. Back then, the world was still very much in the 'steam age' where heavy castings and the need to keep the cylinders hot, were the norm. The age of manned flight needed a complete change in design philosophy and construction methods. The engines needed to be light weight and also needed to be cooled. Deep fining of the cylinders and especially the cylinder heads was not yet fully understood, so spinning the cylinders seemed a logical step at the time; although that complicated the art of flying the machines. I find it amazing, considering the simplicity of the machine tools available, that they were able to make those thin walled cylinders with integral heads. We are talking about wall thicknesses of a millimeter or two. The French lead the way, first with the Gnome and then the Le Rhone engines.

There is anecdotal evidence, that in the early years at least, there was an unwritten Gentlemen's agreement that any flyer forced to land behind enemy lines, due to the effects of the Caster oil would be allowed to take off again afterwards. This was when gentlemen fought air battles, things soon to became more uncivilised and serious.

Mike
« Last Edit: September 06, 2021, 10:53:16 PM by Vixen »
It is the journey that matters, not the destination

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Offline Elam Works

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Re: The Le Rhone 9C
« Reply #12 on: September 06, 2021, 10:12:22 PM »
Craig,

Well, easier to change things on the computer than after metal has been cut. Unless you were aiming to build that rare, reverse rotation LeRhŰne used in the southern hemisphere where the drains run the opposite direction..  ::) 

The 80hp LeRhŰne has some tricky milling in the cam case for cam follower clearance that would have made for some challenging machining, as well as some thin walls. The 110hp eliminated that and was a little better in that manufacturing respect, but the trade off is it is a more difficult shape for the trepanning operation to carve out the cavity. All done at the time with that new wonder tool material, High Speed Steel!

I did not go into the  Willock building at R&T this year as none of the exhibits in there 'ever changes'. Pity, as I missed out on seeing the Otto & Langen models.

-Doug
« Last Edit: September 07, 2021, 05:55:07 AM by Elam Works »

Offline Craig DeShong

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Re: The Le Rhone 9C
« Reply #13 on: September 07, 2021, 03:42:01 AM »
Doug

Sorry I missed you at R&T this year.  You need to take a swing through the Willock building though as things have changed.  Along with the excellently executed Otto & Langen models  :lolb: you will see a full size 3rd generation Otto & Langen, built by Bill Hazzard and a very early, 1885? Deutz engine on loan from the Henry Ford Museum.  Also, the O&L Crossley, which has been at R&T for abut 4 years now.
Craig
The destination motivates us toward excellence, the journey entertains us, and along the way we meet so many interesting people.

Offline Dave Otto

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Re: The Le Rhone 9C
« Reply #14 on: September 07, 2021, 03:21:49 PM »
Another interesting project Craig, I will enjoy following along.

Dave