Current HMEM logo photo inspires another Owen Mate dirivative

[edholly]

I feel very privileged to have an engine I built some time ago as the current photo adjacent to the HMEM logo.

It comes from a thread I started back in August last year and can be found at

Link removed as error - see linka couple of paragraphs below ...

I haven't had much time for building engines lately, the restoring of a Series 2 1964 Lotus Seven and a 1961 Lotus Elite have stolen that. But the bug is strong and I did have a play with a horizontally opposed twin based on the Owen Mate, which I have now realised is not going to work in its present form.

So I have left some over Owen Mate componentry and have decided to make my 4th "Mate" - this time simplifying David's design yet again. In fact I have made the crankcase in just 5 hours - albeit that it will have a radial mount not a beam mount - and will have bolt on nose and rear cover/mount.

So here are a few photos of the new Owen Mate on its way. It is intended to power a 60inch wingspan Tomboy hopefully all finished for next year's Oily Hand weekend. The ill-fated twin crankcase is also shown.

Oh and the reason I spent 3 hours on the case this arvo - Sydney hit 41 degree Celsius and my garage is the place to be when it gets that hot !

Have to comment on my DRO's - when I drilled the holes on one side of the engine block for the front mount - then turned it over to do the rear cover ones - the drill broke through 100% on target to the front holes. What a marvelous piece of kit this is - and I could NEVER achieve anything like I do without it. How did they do it before these were invented - have to admire those that worked without them.

One again thanks HMEM for using my engine in the present logo, and thanks again to David Owen for a truly wonderful engine the amateur can build and run ...

Just noticed link to previous doesn't work.. try this one ..

http://www.homemodelenginemachinist.com/showthread.php?t=23458

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[quinette7]

Great project idea! I am eagerly watching your progress.

Bob

 

[edholly]

Managed to find time to make the muff - made it attached to a mandrell off the end of it to hold it as I had given the muff a taper and didn't want to mar its finish in the jaws of the chuck.

Worked out pretty well. Made it look a bit different to the other Owen Mate muffs. Yet to finish the crankcase, might put in the 4 jaw and turn it rounded on the edges rather than a taper to a square at the top. The things we do for aesthetics!

Had a cylinder left over from previous builds, checked with my recently bought second hand Diatest bore guage, and it is internally near perfect - in fact will use it without any more work it is that good.

Trial assembly in 3rd photo is engine on the right, next to Owen Mate No.3 and the Owen Mate Inline Twin.

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[ixb1]

This engine will be sideport like ML or any RRV,Reed valve ?

 

[edholly]

Here's the finished engine.

First time I've used a throttle and it idles quite well, but quits when opened more then about 60% - suspect the venturi size it a bit big and airflow slows at full throttle and suction decreases even though I've tried it richer.

Here's a short video of it running and some photos.

Once again thanks to David Owen for a design that is relatively easy to build but has an abundance of power.

Ed

[ame]https://www.youtube.com/watch?v=U623TxxqPP8[/ame]

 

[ixb1]

Nice build.
Do you plan enlarge this engine to about 5cc ?

 

[edholly]

Nice build.
Do you plan enlarge this engine to about 5cc ?

Hadn't thought about that - but it would make a super powerful engine that's for sure. Might have to make a triple size Tomboy to use all that power !

 

[Niels Abildgaard]

The strange and wonderfull 60 degree engine indicated that striving for minimum crankase volume is not the whole story.Will it be possible to test it on Your new engine making a suitable rear cover?

 

[edholly]

Neils, one day I will get around to making a backplate that allows a lot more volume in the crankcase and see what happens on a back to back test, I too am curious.

I gave up on the throttle, no consistency, so made a normal venturi inlet with a PAW NVA. This then ran to 10300 with my test 9x4 Turnigy wood, showing a few hundred revs more that the other 2cc Owen Mates I've made. Now this is interesting for 2 reasons, firstly the inlet hole in the crankshaft was simply eyeballed at 45 degrees BTDC so by no means scientific, and secondly the compression is just a tad softer than I would like and with no taper at the top of the bore, which means it has even less compression hot. However it starts very happily and continues to run with the comp screw backed right off.

I chose a beam mount as I have found this is a pretty easy way of mounting an engine these days, and intend to find a more suitable throttle for it in the future, maybe one from a PAW 1.5cc might do the trick.

I have attached a photo of it as it is presently.

Also have put in a link to a video of some super8 film a mate gave me from when I flew a model Britten Norman Islander I built from plans I drew up - that was 1975, just 40 years ago ! .

[ame]https://www.youtube.com/watch?v=vLX6yoi9gmQ[/ame]

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[Niels Abildgaard]

Hello Ed

If You make a new backplate make it variable volume as well?
Maybe screwed fully in (something like compression adjuster?)
is good for starting and another position for full blast running?
The video will be something special with three adjustments to get max rpm