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Flying the AMA Twin Sport Utility

I have flown this bird about 8 times now and each flight is a little different. There is a brief article in this month's MAN that detials a simple way to synch the engines so that is how I am doing it now. Due to the newness of the engines though, it requires a re-synch each time I fly. I hope they break in soon. Anyway, I was flying yesterday and the port engine quit. I hardly noticued it was out. The plane still flew very well but would not turn into the dead engine side. I rmemeneberd my engine out procedures and started flying to the right keeping the speed up. Landed with no problems so it does well on one engine. Since I am using twin Magnun 46's I have had to go up to a

12x4 prop to keep the speed down as it really scoots with anyhting else. One word of caution if you build this. Take off at FULL throttle. I tried half throttle the other day and the controls were mush. Not enough airflow over the control surfaces to gain positive control after rotating. Once up, I increased the speed and all was OK (until I lost an engine). She is a speed demon but not built for 3-D. Just enjoy the sunday afternoon flight.

Ted

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Ted
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Synchronizing the engines on a model is much less important than tuning them to run reliably...

/daytripper

Reply to
daytripper

Reply to
Fubar of The HillPeople

A few hundred rpm difference between the engines is of absolutely no consequence. Let that one get out of your head.

There were electronic devices that had a sensor on the slowest engine and that signal went to a box that slowed the second engine (which also required a sensor) down to match the slower engine. Both engines were originally tuned independently for max reliability. This is the ONLY way I can see to do it reliably without getting into a lot of mechanical work on the engines - and all for nothing.

Yes, Charlie (CR), I know you're watching my absolute proclamations. This time, before criticizing me for making such a proclamation (which is only done to stir dialogue), come up with an answer to the synchronizing problem FIRST.

Ed Cregger

Reply to
Ed Cregger

Reply to
Ed Forsythe

I hate to disagree but if they are synched, they are tuned. Part of the synch process is to tune the low end on each engine and then the high end. The synch process comes in when you determine which engine is the "stronger of the two at optimum RPM and then you richen that slightly "weaker" engine to bring it down to the lower rpm running engine.

Reply to
Ted

Unfortunately, you can't post pics using the Google news reader. I will send some to your Yahoo email if you don't mind.

Reply to
Ted

Well Ed, glad you told CR off. He's been a pain in the butt ever since he fouled up the Kerrville TX RC club. But, be that as it may, my EXPERIENCE with twins has taught me to get the high end RPM match as close as possible. Its a personal preferenece and not a hard and fast rule.

Reply to
Ted

in message

Agree!

Reply to
Ted

| Use an accurate tach. TNT is the best, IMHO.

Aren't all the modern optical, electronic tachs of similar accuracy -- i.e. they're all almost perfect? And if your flourescent light isn't rotating at 3600 rpm, either you're not in the US, or something is wrong. :)

What the better ones give you is better sensitivity -- you don't have to be so close to the prop, lighter weight, less likely to break if dropped, etc.

Reply to
Doug McLaren

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