Dr1Driver

Hi all,

Does anyone have any experience with the Arizona Model Aircrafters 1/4 scale rotary Gnome or LeRhone engine kits? The ad blurb on their web page says the builder must add some brass or aluminum tubing and "hardware". Can anyone tell me exactly what's needed? It seems like I'd do just as good (and cheaper) with Williams Brother's scale engine cylinders and a scratch crankcase. Any info is greatly appreciated. TIA!

Dr.1

US185Damiani

WB are very good and soon the whole engine will be available again.

abufletcher

I think the AZM "kit" is really just a set of WB LeRhone cylinders and some wooden parts for a crankcase to mount them on.

Dr1Driver

Thanks abu. Frankly, that's what it sounded like from the description.

US185, do you know when the WB engine will be available?

Thanks,
Dr.1

mdelzer

Glenn Torrance has a kit that uses the WB cylinders....pretty economically priced at $8.50 for the crankcase kit and $4.50 for each cylinder. Glenn's kit will only give you the bottom 4 cylinders, it is not a full kit.

Mark

abufletcher

Was the "whole engine" ever available at 1/4 scale (3" scale)? I only remember a 2" scale (1/6) kit.

Dr1Driver

I'll check into that, mdelzer. Thanks.

Dr.1

destrat

Dr1Driver:

I built the DH1 in quarter scale from AZM a number of years ago, and the kit for the 120hp Beardmore was nothing more than a bag full of wood parts along with a few plastic pieces of stock to make parts from. It took a while to come up with an engine from this kit, and believe me when I say that AZM offers no support! Good luck, personally I would go with GTM's Or Mick Reeves scale engines.

Dr1Driver

Haven't heard of Mick Reeves. I'll check him out.

When I wrote AZ to ask if the engine cold be made to rotate, the answer was a simple. "It has been done." The more I looked at the pics, ad blurb, and instruction sheet they provide for downloading, I realized their "engine" was jut 9 Williams Brothers cylinders and some plywood.

Thanks.

Dr.1

abufletcher

"Made to rotate." That's a tricky phrase. What I've heard is that a dummy would be unlikely to survive long if rotated at the actual speed of the engine/propellor. There seem to be two general solutions to this dilemma. The first is to really just let the dummy "freely spin" in the airflow something like a pinwheel. The second (on some aircraft types) is to use a reduction gear setup.

Bear in mind that a spinning rotary engine was mostly just a semi-transparent blur.

Dr1Driver

That's what they have in mind. A ball bearing in the crankcase of the dummy engine that allows the engine to spin on the prop shaft with the prop airflow. A dummy radial spinning at 8,000 wouldn't be very scale. I don't think those old rotarys ever got over 3,000.

Bear in mind that a spinning rotary engine was mostly just a semi-transparent blur. Yea, but it'd look great taxiing out and idling on the ground!

Dr.1

BobH

My Feedback: (2)

Here's a picture of my Mick Reeves dummy engine. It's for my 1/4 scale Camel. As you can see its a Clerget.

jtisch

IIRC, LeRhones and Oberursels turned 1200 RPM and at 1500 you risked throwing a cylinder. One reason rotary powered AC were never considered good "divers". Go too fast and OOPS, there goes one!

splais

My Feedback: (25)

Bob, does that open dummy engine provide adequate cooling without any other holes? also, how much distance did you need between the back of the cowl and the engine. I've been trying to get the info from Reeves, but getting them to answer an email is a real chore. Heck, they will not even acknowledge an order I tried to do.

steve

BobH

My Feedback: (2)

Steve I believe the engine will let the real engine cool properly. I'm going to use a Laser 200 inverted and others with the same set up are not having any problems. As far as the distance needed I'll have to measure it and get back to you. FYI It fits in the Camel cowl in front of the Laser ok.

abufletcher

The first photo below uses a long shutter speed to simulate the look of a LeRhone rotary in motion. As you can see, it's mostly a coppery-looking transparent blur. The second photo is of a LeRhone (type C). The third shows my modifications to a WB 2" scale LeRhone kit to make it more like the Oberursal used in the EIII.

BobH

My Feedback: (2)

Steve my engine is 2 3/16 from the front edge of the crankcase to the back of the cylinder head. And that's 1/4 scale.

Dr1Driver

Great pics, abu. I can't find any good pics of the back of the Gnome engine. Do you know where the spark plug wires attach in the back? Is it a stiff, straight wire or is there some slack in it? Thanks!

Dr.1

Teus

Hi Dr1,

I found this picture for you. Here you can see the attachment points and that there's a little slack in the wire's.

Teus

Dr1Driver

Thanks for the picture, Teus. Great detail shot. I still can't see where the spark plug wire goes into the crankcase. I assume the distributor is internal? And the exhaust goes through the crankcase? I see no exhaust tubes in any Gnome picture I've found.

Dr.1

Teus

Hi Dr.1,

Take a look at the following document [link=http://www.enginehistory.org/Gnome%20Monosoupape.pdf]Gnome Monosoupape Pdf[/link] from the enginehistory website. I'm sure you will find what you are looking for[8D]

p.s.

I updated the previous photo.

Teus.

Teus

And take a look at the following picture from the same website: [link=http://www.enginehistory.org/G&jJBrossett/USAF/Gnome%20N-9%20rotary%20view.JPG]Gnome[/link]

Here you can clearly see the exhaust valve on top of the cylinder and why you couldn't find any exhaust tube's. The exhaust release is in open air on top of the cylinder.

Teus.

abufletcher

Interesting reading -- particularly the part about it being fairly normal for the engine to catch fire during start-up!

Dr1Driver

I'm learning a lot about this little engine! Thanks guys!

Dr.1

abufletcher

BTW, DrI, are you building a Gnome/Oberursal or a LeRhone? I had assumed by your moniker it was a LeRhone. The two engines were really very very different and modelers tend to put the LeRhone in everything.

The WB kit is extremely detailed both from the front and from the back. I ended up using only about half the parts in my kit-bash to an Oberursal for my EIII. I used the cylinders and the crankcase but had to fabricate my own "forward crankcase" with styrene and one of the plates (with bolts) that was supposed to go on the back of the engine. The cylinders on the LeRhone were too short and squat for the Oberursal so I added rings of styrene to the bottom to lengthen them. Also the rocker levers on the top are all wrong for the Oberursal (and maybe even for the LeRhone). So I cut them off and fabricated my own. I also didn't use the extremely fragile plastic rocker rods that come with the kit. Instead I used music wire wrapped in aluminum tape.

Oh, and I believe that "the NEW William's Brothers" offers 3" scale Gnome cylinders like the one in the photo below.