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Old 03-02-2008, 10:07 PM
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ProBroJoe
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Default RE: Avionnette HM-8 build thread.

BMatthews
Joe, I saw the vid but it's an engine spinning a prop. It didn't indicate what the performance was.... or wasn't...
What??? The second video I linked to shows the engine idling at about 5,000 RPM, and throttling decently up to about 13,300...

ProBroJoe
More good news - I finally got around to firing up The Twin since the rebuild. It actually hand starts fairly easy - providing you can supply enough current to the two glow plugs. I had to have my power panel cranked all the way up - which would blow a plug should the other accidentally become disconnected - happened twice, once on the original Glo Bee flat wound plugs, and once on a brand new OS A3s... I then switched to some Hanger 9 idle bar plugs which took less current to light and were more forgiving of oopsies. I lost almost 1,000 RPM over the Glo Bees, but the idle and throttle response was pretty good. As expected, this engine is no powerhouse as it only spins a MAS 7x4 scimitar at 13.250 RPM (14,000 on the glow bee plugs), but it's idle is pretty darn reliable and it's very user friendly. I shot a short video today which tells the tale. Check it out: http://home.comcast.net/~jbwebst/gmt.wmv
But hey, I didn't come here to nit-pick, I just wanted to share some progress. It's been a little slow going.... OK, it's been a lot slow going, but hey, it's going. I'm really limited on space to work right now and am forced to work with an X-acto and straight edge - not too fun when working with lite ply (no power tools here). I'll most likely make the firewall out of 1/8" aircraft ply since I am going up with the engine weight and forces, but I think the rest of the airframe will be OK. A lot of the forward section is lite ply and should hold up well - the twin is a real smooth runner.

I'm debating on whether I should build a flat wing and add ailerons (as the original had) or just build it as a rudder-elevator model. Also, I think the G-Mark is a nice fit on the firewall, and if you look closely at the second picture, you can see the outline of the Cox reedie along with it's dummy cylinder. Funny how the G-Mark fits within those confines....

-Joe

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