New Twin Questions - RC Groups
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Mar 03, 2012, 11:58 PM
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New Twin Questions

Hey Guys,

I have a new Aerodyne Baron on the way. This is going to be my first twin aircraft. I'm going to be powering with x2 O.S. .46ax. Just curious about glow drivers and engine synch. I was looking at an engine synchronizer that they have on Troybuilt models. They have an option to hook in on board glow drivers to it. They have their own brand, but I was thinking of getting a Sullivan instead. Anyone have any thoughts on these two things? Is the twin cylinder on-board glow from Sullivan the same as 2 engine, or do they have a different type? Any brand that would be better than Sullivan for this?

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Mar 08, 2012, 12:45 PM

There are lots of options, and probably even more opinions, on those topics. Here is my $0.02...

On my B-25 I use the Sullivan twin cylinder OBG - it is really intended for a 2-cylinder engine but I use it to light the left and right engine glow plugs simultaneously. I only use it for engine starting so that is no big deal and it let me drive it from an existing battery that isn't used for anything else on the ground. If you want to link OBG to throttle setting (which I don't much like) then you may be better with something like a RAM50 for each engine.

As for engine synchronizers, my view is that they are really overrated and may cause more problems than they solve. It's pretty easy to use the throttle curves in your TX to get the engine rpms very close such that you won't notice the difference in flight. Just be sure to optimize the tuning for each engine and then throttle back the faster engine to match the slower one. My concern with the sync units centers around an engine out situation; by the time you figure out what is happening would you have the presence of mind to pull the throttle back to idle in order to regain manual control on the remaining engine in time to avoid the dreaded death spiral?? I feel that maintaining reliable engine performance is more important than an exact rpm match.

Mar 08, 2012, 02:18 PM
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Hi Ron,

Thanks for the info! I had the same thoughts on the synch in regards to a dead engine. Just wasn;t sure if it was a must have thing or not. As far os the on-board glo goes, I do want something I can light the plug with as I come down in throttle. Not sure if I'm going to put it on a switch or have in auto on the throttle. I just don't want the 46's flaming out on me when I bring the throttle down. DO you know if they make a glow driver that can power 2 engines this way, or do I need 2 seperate units.

Mar 10, 2012, 11:05 PM

It's really up to you. I have the Sullivan unit controlled from a switch as I wasn't sure in the beginning if I would want to use it for more than just engine starting. It can happily light the plugs on both engines at the same time - as far as it is concerned it makes no difference whether the 2 plugs are on the same engine or different engines. I do recommend powering the OBG from it's own battery as I found the unit generates a lot of electrical noise on the power lines that can upset other electronics if you put them on the same battery.

There are lots of approaches that will work well. Other constraints like number of batteries to charge, wiring complexity, redundancy concerns, and personal preference will probably make the decision for you.

Mar 12, 2012, 11:20 PM
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Go for it. Nothing sounds like a twin. Snyc is not a huge problem just $$$$
Tune the strong engine to match the weak one....not the other way around.
Good OS engines will run very close, even if the don't sync at full throttle, pull back to 7/8 or 3/4 and they probably will.
You MUST be rudder capable, at some time one engine WILL quit. Throttle back, and use the rudder to maintain your heading.
Depending on your choice of radio, some computer radios have 2 channels for throttle....a real nice touch.
Last edited by corsair167; Mar 12, 2012 at 11:21 PM. Reason: additional info
Mar 15, 2012, 10:10 PM
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Thanks guys. I'm about half way through the build on the Baron so far...just need to get the gear and engines. Thanks for the advise on the rudder. I've been reading up on flame out recovery so I have been practicing on the sim with a twin and having an engine die...just so I can get used to the feel for it. i think for the OBG I'm going to go with the Sonictronics twin glo--Mcd472TE. Seems like a nice unit. I am going to pass on the synch. As long as theengines are running good and the plane flies, I'm happy.
Mar 16, 2012, 07:47 PM
Registered User
Another thing to remember is how much run time you have on each fuel tank. I found out the hard way with my B25 when an engine cut and had to gently bring it back on one but didnt quite make it!!!! Was really enjoying myself until then .Was running a pair of asp 52 4strokes without any glow drivers with no problems, just had to experiment with different glow plugs and ended up using os type f .

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