2 motors (brushless) will require 2 speed controllers. There are a few that have been (claim) successful in using one speed controller for two motors, but there are ramifications and side effects that can rear up. Both props can spin in the same direction and there isnt anything special to keep in mind. The two speed controllers controller leads will be hooked up to a Y harness and then plugged into the RX. One battery can be used, but the voltage will need to be higher to run both and the amp rating (on the battery) should be high enough to handle the current.
A 3 cell pack can easily be used on the same motor that a 2 cell is used on. That is one of the things that make Electric motors so universal. The thing to keep in mind is as you change cell count up or down, something else has to change. Lets use the Axi 2808/34 setup recommended as an example.
Lets say an AXI 2808-34, CastleCreations Pheonix 10, and 2S TP 730 swinging a 10x3.8 produces 8 amps. When you put a 3 cell 730 pack on there, it now pulls 11.5 amps. You are now over the continuous rating of the Pheonix 10 and more amps (16c) on what the 730 can deliver without harming the pack. You now have more RPM's, but while the amps increase. In order to maintain it within spec's, you will have to drop the prop to a 9x3.8. This lowers your amp draw while maintaining the advantage of the extra voltage. This may drop the amps back around 8-9 amps.
The rule of thumb is that as you increase voltage, the prop has to drop (assuming it is running near spec levels on the battery and controller). And as you decrease voltage, you increase the prop diameter and/or pitch. For motors to be efficient they have to run at a certain amp draw. To maintain that amp draw during voltage changes (trying different packs), you juggle the prop to keep it within the window. Clear as mud?
My heaviest shocklyer was 10.5 oz (with 3cell 830 pack). This is a bit of a porker for these planes, and it still flew great. It flew a lot better the lighter I got it though and verticle performance was pretty linear. The 340 packs are great for indoors, but for outdoors, I prefer around 700mah. I fly with 2S TP 730's on my two now. Easy 10 minute flights with power to spare.
-Mike
ORIGINAL: Prophex
ok, one final question:
If you want to fly a plane with 2 electric motors ... do you then also need 2 speed controls or can you hook up one esc to both the motors ? (and anything you should keep in mind when doing this ? like maby make one motor turn clockwise and the other one counter clockwise or something ?)
I also did some more looking arround for info and it seems that hobby lobby had a nice explenation on what to get for which motor and such. And it seems that powering the AXI 2208/34 with a 3-cell lipoly pack gives it almost the dubbel RPM. Would it be wise to then use a 3-cell lipo instead of the 2-cell ir will I have weight issues with the small shockflyer ? Also, hobby-lobby seems to recomend low-mah batteries like 320 mah or so, but I would prefer something like 720 mah. but again, will this be a good idea, caus these batteries also wheigh alot more. (or won't it make difference ? I was under the impression that the more mah, the longer your flight time)
thx for all the input guys,
Prophex