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[vbentley]

I volunteer at the Canadian Museum of Flight in Langley, BC. Among our storage items is a 4-cylinder 2-stroke engine that was supposed to be a McCulloch or similar.
On examination I found it had the name Nelson cast into the front of the crankcase. This was interesting as we have a Bolus Dragonfly powered glider on display. This engine was originally in the glider - removed as at 25hp it didn't do much to get the glider airborne.
I have started stripping the engine to clean it up for display. Does anyone have any technical information/specs/cutaways for this engine. There were only 7 Dragonfly's built so probably not many engines around.
http://www.enginehistory.org/BBimages/BentleyV/Nelson5605.jpg
http://www.enginehistory.org/BBimages/BentleyV/Nelson5607.jpg
http://www.enginehistory.org/BBimages/BentleyV/Nelson5617.jpg

[vbentley]

Here's an update on what I have found as I have stripped it down the Nelson H-44. It was fitted to a Bowlus motor glider, an example of which we have suspended in the Canadian Museum of Flight. The fairing at the rear was fitted after the engine was removed.


Engine components as removed.
Distributor drive with rubber coupling.
Carburetor flange with swirl vanes.
Rubber belt connecting starter mechanism to crankshaft for ground or in-flight starting.
Cylinder heads coming off; interior still oily 60 after years since last run!
Crankshaft and central diaphragm. Con rod bolts have plain nuts with spring washers for retention.
Cylinder heads after bead blasting looking as good as new!

[klankenau]

Considering the production quantity, application and era, any "manuals" were most likely limited to several pages of basic information, typewritten and mimeographed.

An interesting piece of engineering. There were a lot of specialist (non-aero) engine manufacturers in the pre and immediate post war era. I'm guessing that it shares components from something more common or it would have been a very impractical and expensive experiment.

[vbentley]

Yes, it is a long shot to hope that someone had a manual or some tech description in the back of a drawer.

I have a manual for McCulloch O-100 engine used on the Northrop KD2R drone and most of the tech details are very similar - except it is a larger engine of up to 95 hp. Nothing that I have found so far suggests that Nelson used McCulloch parts or design, but details of the ignition system are very similar.

Not having anything to do with 2-stroke engines more complex than a lawnmower it is all new to me!

[tfey]

I just acquired an H-44 (bore 2.2.5; stroke 2.75) and it has just 4 studs on the cylinders, the carb flange is on the centerline of the engine, and there are no studs or flats on the exhaust ports. I believe the engine you are very nicely restoring is a Nelson H-59 of 40 horsepower. Can you please tell me the bore and stroke of your engine? The engine displacement will help identify the model of engine. Thanks. Tom Fey

[vbentley]

Thanks Tom for the comment. My summer time has been very busy and I can't find the dimensions at present. Will pass them on soon. Vic

[vbentley]

I measured the bore as 2.625 and stroke as 2.75 in. This may make it the H-59 as you suggested, but I can't find reference to the bore of that engine. The Museum presumed the engine was the H-44 that came with the Bowlus glider we have on display - but after all this time who knows?
The other mystery is how the engine mount was fitted. The lugs for the mounts are not in the open and would not take a normal mount as per Continental/Lycoming. A picture of another in this family of motor gliders shows a circular tube steel engine mount.
Would appreciate any info you have. Vic
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