Twin motor setup advice

Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:

1. Run the motors in series. That way if one craps out they both do and you will not have the problem of the bird corkscrewing in.

1. If you are using BRUSHED motors you can use one ESC. If you are using BRUSHLESS motors you will need an ESC for each motor.

2. I suggest 1 pack. It will make life easier for you.

1. D/L a copy of MotoCalc (free to use for 30 days). Once you plug the info in on the plane, the program will recommend several motor/gear ratios and prop dia x pitch for optimum performance. The program will also give you a good idea of the performance, flying time and skill level needed for the plane.

"Ted Campanelli" wrote

First, let me say I have never run a brushless motor, so I am far from knowlegeable (but always eager to learn) about electric planes running brushless motors, or even plain motors.

I thought I had read that if you used twin (exactly the same model) motors, that you could split the controller output and run two motors off of one brushless controller.

No?

The message from "Morgans" contains these words:

Hi Jim,

This would be lethal with the Me 210 anyway as it was a lousy glider and quite unstable with asymetric power, thats why they stopped production of the thing and redesigned it as the Me 410,

regards, Terry

The message from Ted Campanelli contains these words:

Hi Ted, after working on the only surviving Me 410 in a complete condition for two years in the early 80's I have always had a hankering to build a good sized flying model of one but have only managed to find a decent plan from 1964 of a Me 210, even this needs conversion from C/L to R/C so I need to tread carefully. This is a project that I will probably start next winter but want to get everything sorted and ready so I can have a summer of learning to fly R/C then look at bigger stuff, I have had an interest in aircraft and their technical side since I was a kid and watched Spifire F22 and F24 flying around and flew C/L and F/F aircraft but never had the finances for R/C, now I have decided it is something I want the satisfaction of having done before I get my wooden overcoat complete with brass handles,

regards, Terry

Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:

If you need plans, go on RC Universe and in the members section look up "1/8 Airforce". He will do CAD plans from a 3 view. The cost is ABOUT $15 per foot of model wingspan.

I had some plans done by him for a Transavia PL-12 Airtruk and was VERY pleased with the results AND the price. For the Airtruk Frank included a materials list and some other information also.

Hope this helps.

Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:

Brushed motors you can run off one controller, not brushless. Some people have managed to get 2 brushless running off of one ESC, however it is not reliable.

There was a write up about a 12 - 18 months ago in one of the magazines on wiring twins (MAN, Fly RC ?? ). They went into a bit more detail about why you need an ESC for each brushless motor.

I have an Aeronaut CL-415 (water bomber) that I am running 2 MP Jet

25/35 motors on. I am using 2 Castle 35 amp ESC with the BEC disabled on one of them and (at present ) a 10 cell 3300 sub C pack.

One thing you need to be aware of when using 2 ESC - You will need to program each ESC separately (just unplug the other ESC from the "Y" in the receiver for programming )

MotoCalc was extremely close with their predictions for the plane/motor/gear ratio/battery/prop setup. I "played" with a couple of different prop pitch x dia and gearbox ratios and came up with a winning combination that is slightly more powerful than the setup suggested by MotoCalc. I am getting less time than predicted by MotoCalc, however that is most likely due to "less than ideal" throttle management and the changes I made in the ratios and props..

Hi Terry,

I once emailed Castle Creations with that very same question and their reply was that it's better to use a single battery (or two in parallel connection). They also suggested using 2 off ESCs, one per motor. For specifically Castle Creations ESCs they recommended connecting both ESCs by a Y-lead to the RX which acts to double the permissible BEC current - other makes of ESC may not support this parallel BEC arrangement.

ISTM that you might be better off looking at a couple of outrunner brushless in place of the geared 480s both in terms of weight and thrust. You would probably get better battery life from a brushless setup as well.

Hth,

I understand this can work sometimes but it is sometimes unreliable in terms of (one or both) motors failing to start.

If you go this route then IMO its better to use a combination that's already known to work reliably in this mode.

Depends if you are using brushless or not..brushless don't take kindly to being fed from one ESC.

Your choice. No big deal. sometimes with two motors and two controllers is convenient to have tow packs.

44"? not very big..most C/L stuff was grossly overowered to overcome massive line drag.

more than enough if built lightly..that's quite 'rocket ship' in fact for 44"..

3s LiPO and about an 8x6 or 8x8 prop will give you lots of poke. 9x6 is more for 8 round cell type power.

Completely wrong.

Its like running tow brushed motors off one commutator. If they happened to get in step it will work. If they don;t, the chances are they will both stutter and smoke.

There is no way to guarantee which will happen. Some controllers and some motors start reliably. Some motors and some controllers never start reliably. Some combos run if the motors are given a flick.

If the combo DOES run it sounds great, because they are absolutely synchronized.

If you have a spare channel and control and a mixing TX you can synchronize the motors by hand also with two controllers.

One brushed controller never achieves perfect synch at all.

Hi,

I have thought of tidying up the plan redrawing feint lines etc and have it enlarged to a proper scale size around the 60'' span area, I dont want to go too big as storage and transport is a problem with this particular beast as the wing is one piece.

I do have a nice pair of Graupner 400's with 2.33:1 boxes but may still use the 480's if I increase the size, I am not looking to break the sound barrier only have enough power to fly safely and not have the model wallowing around like a sick pig.

I had decided to stick with the NiMh/brushed motor setup to start with but I must have a look into Li=Po etc as it seems the advantages far outweight the problems I may encounter, could always charge them in a fireproof area in the shed because it is brick built. I have a new pair of cheapo Emax 2812 brushless motors in my box which may take 8'' props, have to have a look and see what the full spec is and if they are suitable may go down that road,

best regards, Terry

People are charging them in flower [ots with a bit of slate plced on top. Other ideas are firesafes and other special bits of kit but I like the flower pot idea because I'm a cheapskate :-)

Sounds ideal, let us know what you decide.

Cheers,

If you are running brushed motors, one ESC is fine. If brushless, you MUST use two ESC's

Absolutely never use absolutes.

It can be said that this is good advise in most cases, but it has been shown that some have had success using one brushless controller in some limited cases.