Matchbox question?
 

If anyone has experience using the MSA 10 Futaba matchbox or the JR variety, I would like your opinions on my set up.

My aircraft is going to be in the 25-27 lb range. My servos to be matched are going to power my landing flaps. They are 3" x 60" long (total area). I have a 3 piece wing, so I am using 4 servos, as the flaps get split at the wing separation point. So essentially, I have 4 flaps. I actually used a tongue and groove joint at the separation, to keep the intersection joint clean and tight. For RX power, I am using 2- 6.6 volt A123 batteries, on separate switches.
The designer recommends 120 oz. servos for the flaps. Mine are around 130 at 6 vols, and are metal gear. The flaps will only be used for landing, so the servos will only have to handle lower power settings (not like a 3D aircraft with multiple servos on a big aileron).

My question, I want to put all 4 of theses servos into one matchbox. It will take 4, and they can be adjusted independently. Also, it facilitates the ability to accept a battery of it's own to power these servos. I am thinking strongly about doing this. I have seen some comments in other threads (old) where they do not recommend putting more than 2 servos into a matchbox. Will it be OK to use one matchbox for 4 servos? Especially since it will be for flaps, and I will add a separate power source.

Thanks in advance for any opinions.

I am also interested in this .I have 2 aircraft that will use very similar flap configurations (1/8 scale DC3/C47 and 1/6 scale AT6 . I have set up the same planes before without matchbox just mechanical matching and mixing multiple channels. Always looking for better /easier/reliable options..

You should be fine as long as you setup the servo linkage so that when the flap is in the fully extended landing position the clevis pin, pushrod, servo end clevis pin and servo arm screw are all in a straight line. This provides an over-center lock of the flap and removes a lot of the flight loads from the servo allowing it to draw less current.

Both would accommodate your needs and while it might give you a warm and fuzzy you dont really need a separate battery with the capacity you're already carrying.

Thanks for the replies guys. I guess I was thinking the specific flap battery would be beneficial, since I have some other battery needs other than just the primary surfaces. Such a a lineal actuator on the canopy, landing lights, and I will add cowl flap operation down the road.

Yes Invert, that makes a lot of sense and is a great idea. BTW, this is for my TA 152, I am getting closer to being finished now.

Separate battery on the gear I could see, flaps, not really, again, you have more than adequate power for what you're doing.

Having the linkage set up the way Invertmast suggests, is actually the way I have it, and is the way the design is laid out on the plans, will really make it a not issue. With the flaps fully extended, the pushrod is pushed square to the output shaft of the servo. I can push down on the flap, when fully deployed, and the servo exhibits zero buzz. Telling me that the servo will experience zero load, or no amp draw when extended. I am very confident in this setup now. Thanks guys.