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 "TOM O's" KIT-BUILD Top Flight Cessna 310 Twin Page 6 |
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finally received the TwinSync system that has been on back order!I decided to also install the optional twin glow driver system that works off engine RPM as measured by the TwinSync sensors. Installing the batteries for the glow system took some thought, as initially I was going to install them on the outside of the engine box inside the nacelle. Even though there was plenty of room for this configuration, a test fit of the nacelle showed that the batteries mounted this way would make it more difficult to attach the nacelle. I was also concerned with adding more weight forward of the wing, which would put more torsional stress on the already torsionally weak wing spar. I ended up making a custom wire harness that fit two 2700 mAh NiMh batteries in a parallel circuit in line with a 2.5mm closed circuit socket for charging. This will provide 5400 mAh at 1.2 volts to power the on board glow circuit on each engine, which should be more than enough for a day of flying. The closed circuit 2.5 mm socket will automatically disconnect the glow driver circuit from the batteries while charging to prevent possible damage to the glow driver circuit. I hard mounted the 2.5 mm socket to the engine box, a hole drilled in the nacelle will allow me to plug in the charger without needing to remove the nacelle. I had to separate the batteries so that the push rod for the flap servo could be routed between them. |
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 Next I had to mount the hall effect sensor for the TwinSync. The hall effect sensor works with a small magnet mounted in the spinner backplate to send signals to the TwinSync allowing the TwinSync to continuously monitor engine RPM. The TwinSync will continuously compare engine RPM of the two engines and keep them in sync. The twin sync is designed to only sync engines when the engines are above a preset RPM threshold, which I can configure. I used circuit board material to mount the hall effect sensor rather that aluminum to make sure there is no interference with the sensor. |
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 Here is another view of the hall effect sensor mounted to the engine mount. I cut out a small hole in the front of the nacelle so that the sensor will be no more than 1/8" from the magnet mounted in the backplate of the spinner. |
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 I routed the wires for the hall effect sensor and the glow driver along the top of the engine box and secured them with tie wraps. The little circuit board in this picture is the glow driver circuit, it talks to the main TwinSync computer mounted in the fuselage to control the onboard glow driver for this engine, there is another one for the other engine. |
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 Here is a picture of the completed installation of the TwinSync for one of the nacelles, complete with the optional on board glow driver system. Looking at this wing I am amazed at the complexity of everything installed into this nacelle! |
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What's left to do:
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Here is the last picture I took before the
maiden flight! This picture shows everything put together except the
nacelles are not mounted. The reason is that I wanted to run and
tune the engines before actually installing the nacelles. I ran each
engine for about one hour and tinkered endlessly to get the low end
and high end mixtures correct. I also spent the break end period
tweaking the Twinsync system. I had a number of problems with the
Twinsync system, but Bill (the guy that designed and sells the
Twinsync system) has been very responsive in helping me identify
that the unit I have is defective, and he is sending me a new one on
his dime. Now that's how customer service should be, thanks Bill!
The good news is that the Twinsync part that was not functioning was
the onboard glow driver circuit. Fortunately the engines are running
and idling so well I did not feel the on board glow drivers were
needed for this first flight. If you were not there you missed quite an event, the weather was a little cold but otherwise perfect. I have not seen that many people at the field in quite a while, many of them were kind enough to let me know they were there to see the Cessna fly, no pressure! Needless to say I was a little nervous, not so much about crashing, I just did not want to do something stupid in front of that huge crowd! Anyway the first flight went off with out a hitch and after about six minutes I landed safely and taxied back to the pits with both engines purring! Thanks for following along on this project, if this bird continues to perform well I might be tempted to invest the $350 for the retracts! If I do I'll have more than $1200 in this "free" airplane! Special thanks to John Shirron for his unfettered commitment to being the Raffle Director, I would never have taken on such a project if it had not landed in my lap, thanks for thinking big and making this possible John! Special thanks also to Dave Anderson who has selfishly invested a boat load of his personal time to make our website a valuable asset to the club, thanks Dave! Someone asked me today if I would ever take on another twin engine project. Even though this was a very challenging, sometime frustrating, and expensive project there is something about the harmony of two engines that will likely draw me to another multi-engine project sometime in the future. If you are thinking about a multi-engine project I'd be happy to discuss my experience in more detail. Cheers! Webmaster note: Tom flew his plane Feb 21, 2010. See the video of the maiden flight here. . . |
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