phyrr

If I were to make a twin engine aircraft, would it be possible to have both engines on the same power line and channel or would that be a resistance problem (as in stereo speakers)?

Sarah

Hi,

You can have two motors working off one power source. This way when the batteries start to go, both motors will go together and you won't have a dissimilar thrust problem, which can induce a yaw and subsequent roll!

Do make sure that the cabling from the single power source, to each ESC, is capable of passing the higher currents of two motors.


Regards,

Saz

lawrencedirksen

When setting up twin electrics with brushless motors, you have to use two ESCs. My question is do you have to disconnect one of the esc's red wires going to the receiver, or can you just leave both attached. I've heard both ways work, is one better than the other?

Bad_Daddy

As long as the voltage output from each ESC is matched within 0.1 volts, there should be no problem with both of them connected to the receiver.
There is an article at the Castle Creations website, in this magazine about the subject: http://www.castlecreations.com/media...03-Mar2006.pdf

lawrencedirksen

Thanks for the info and the link, I shall check it out!

twinman

My Feedback: (2)

Funny you should bring this up. I am working on a "Project" that I had to know just this point. Yes, you can "Y" the reciever connections together and it works. Still need two controllers. I am also working with one Large battery so that one motor cannot fail..OK OK..from battery failure anyway.
Good Luck

Slowjohn

I've been flying a Twin Simple Stick (Simple Stick $29.99 @ Hobby People) that I set up with the ESC's Y-ed together to the receiver for about 4 months now and it works great unless a wire breaks or I hit the LVC. So far I've had the right motor stop on me 3 times and haven't crashed it yet. I set the motors straight ahead and angled slightly down. When the motor stopped running the plane would start a turn to the side the motor is out on, in this case to the right. I'd try to bring it back on the path I wanted and the way it was handling told me something wasn't right so I chopped the power and brought it back up slowly to about half throttle to get it back into the wind and closer to me. The time with the broken wire at the connector it was better to just cut the power and put it down and go walking. It was too windy that day to risk bringing it back closer to me. I have a hard time walking so that was a tough decision in itself.
This Twin SS and a GWS C-47 w/brushless motors are my first "Twins". I'm scratch building a "Twin" Lainer ST-40 from plans to get even more time on before I build my N.E. Aerodynamics Twin-Air .20 (an eBay find) and then a 2/40 size Duellist that'll most likely be scratch built.
Living on the Gulf Coast of Texas there is a fairly constant onshore flow of wind around 15 mph. Flying Twins just seems the natural thing to do. I do have some "over-powered" electric warbirds and a few other powerful electric singles but the electric"Twins" are what I enjoy the most.

Standing By,
Slowjohn

twinman

My Feedback: (2)

You da man. Good looking...now I need to get back on my project. Thanks for the post.

Slowjohn

Thanks Twinman,
Here's a few more of other "Twin" projects. The "Twin Mustang" is a bash of an Ace Simple Series P-51 kit that I used as a pattern to build this one. However I stopped before I installed the radio because I decided it might be a bit of a handful since basically at the time all I'd flown were "High Winged" trainer types. Before much longer I'll finish it as I'm ready to attempt it. Besides I still have the Ace P-51 kit if it all goes wrong so I can start over. Just planning ahead for that "just in case" thing you know.
The other shots are of my ST-40 Twin bash. I started out with a wing that USPS did a tap dance on during shipping. The shoe prints were still on the box. Anyway the wing was broke in a good spot to place a motor nacelle so... I was able to get the plans and scratch built the rest of the ST-40 so I could have a large Twin Trainer however I built the Twin Simple Stick first and then the GWS C-47. I'll get back on the Twin St-40 soon though as I really want to fly it.

Standing By,
SJ

Slowjohn

I forgot to ask you what you would do for the vertical stab & rudder, would you go with a single large rudder & stab or a Twin set-up?

Thanks,
SJ

twinman

My Feedback: (2)

Completely depends upon what you want the plan to do. More aerobatic and more stable, twin rudders and good size. Most twins fly very well with one rudder, but make is big and LARGE control surface.
Best of Luck.
PS Not Politically correct...Merry Christmas

Slowjohn

The original idea was to just have a large Twin electric trainer but now I'm thinking seriously of taking about half of the dihedral out of it so that it'd be more aerobatic. Also every plane I've ever had was a tail dragger so the tricycle gear is for some experience also.

Edit; I shouldn't have bragged about the Twin SS in post #7

Wish I'd of had a steerable nose wheel on my Twin Simple Stick today instead of the tail drag . The 4th flight it suddenly took a left turn on take off before I had good airspeed for rudder control and hit a curb which resulted in it going airborne for a short distance and... well I have quite a bit of repairs to do now. Then I lost my E-Flite Ultimate in the sun on landing and totaled it. Not a good afternoon/evening for my planes today but I have a few more Ultimates almost ready to go and it'll only take a couple of hours to fix the Twin SS.
Back to the Twin ST-40, how much larger should I go for the single stab/rudder over the stock unit? I know what I'd do for the twin stabs/rudders but not for a single unit.

Thanks &
Merry Christmas,

SJ

twinman

My Feedback: (2)

The larger the control surface,,,particularly on a twin the more aerobatic, but also MUCH BETTER CONTROL on engine out. I have gone on a twin fuse ugly stick at 50% larger.
Good Luck

Slowjohn

Thanks a bunch Twinman.
That's exactly what I was thinking I needed to enlarge it to. The reason I decided to go ahead and reduce the dihedral for sportier flying is after I repaired the wing and built the nacelles I noticed that the fiberglass reinforcement was loose and the wing has some play where it joins so I was going to have to fix that anyway.
As usual you've been a big help and I very much appreciate your time and input. Hope to get up your way one day and do some flying as I have a Nephew living in the Katy area.

Merry Christmas, (Always Correct In My Book)
Slowjohn

Mr Electric

hi
i could do with some help with my twin



85" mitchell
2 x AXI 4130/16 's
2 x 70 amp opto esc's
Y lead to rx
please look at the photo below and with one wire not connected both motors run .. does it get its power through the receiver wire ??


by the way i have cut the red wire in rx lead !!

thx for looking

vmsguy

If I read your drawing correctly, only one motor should run.

Question, did you cut the red wire on BOTH ESCs? Or just one.

If you're really careful with a small flat screwdriver (or point of Xacto blade), you can pry up the plastic tongue holding the red wire lead in the connector and put the wire out. No damage.

A pair of 4130/16 are going to draw some serious amperage. Is your battery pack 3 or 4 batteries in parallel? So you're not draining them faster then they can handle?

A suggestion, run your blue wires together, then put your switch between the battery and where they join.



Good luck.. Keep us posted, an electric twin is on my wishlist....

Mr Electric

t88t fk fk fk [:@][:@][:@][:@]
i just spent an age writing a reason and lost it all when it timed out

shiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii--------tttttttttttttttttttt

Mr Electric

this is the very short version
drawing rite blue wire not a switch both motors do run
battery big enough
must get the neg feed from servo wire not reds left in esc 's
the end

Slowjohn

I hate it when that happens or when the electricity goes out and it only happens when it's a long detailed post right [:@]

SJ

Mr Electric

ok i have calmed down a little now and the PC is still in 1 peace

the drawing is right ..the broken blue wire is not a switch its just there to show that the system still runs without the blue wire connected

i have never opened up the thottle because i think its getting it negative from the esc servo wire ..

i have removed the red wires from the esc's

when i reconnect the blue wire i open the thottle and all is well ..im just wondering if this setup is right

battery pack is made of 6 x 3 cell 2200mah 20C 6s3p (22.2v @ 6600mah) should be good for over 100amp

Slowjohn

I'm not sure what you said but I agree with vmsguy. Your drawing if correct should only allow one motor to run. The left disconnected motor should not get any power thru the Rx. lead that would allow it to run. Please check your wiring again and confirm that your drawing is correct. Are both motors running the same? Is the throttle responding correctly, ie; do they power up all the way? Are all the other controls functioning properly? Is the equipment new or has it been in a crash? Are you positive your not shorted out somehow someway?
BTW, Nice looking B-25. Hope we can get it figured out for you.

Standing By,
SJ

Mr Electric

the setup is is

axi 4130/16 with master air 12x6 3 bladed pulling about 17.5 amp (about 770 watts)
im waiting for 2 APC-e 13x10 2 bladed should do about 28 amps (about 1170 watts)

im going to try and take it down to the field today and taxi it about track the nose wheel ..ill take the camera
photos + video hoppfuly ?

Mr Electric

i was amazed too the drawing it correct it runs both motors

but i dont want to run them to fast because it must be getting the negative through the servo lead and that will melt if i turn it up

Slowjohn

You only need to disable one of the red wires on one of the ESC's. Do you have another ESC that you can try in place of the ESC in question? As to your question if you have it wired right, I would say yes to that going by your diagram. I was trying to find a diagram that I have stored on my computer but I haven't located it yet or I'm just overlooking it. I would try a different ESC if it was mine and I had one to try. I'm not sure if you should try another ESC if it's not the same size as the other one but I think I myself would try it for a short moment just to see if it changed anything. That would be my suggestion before I tried running them for any length of time at all.
Here is another diagram of 2 GWS "Twin" set ups. The lower illustration is for brushless set ups and is the one I use.


Standing By,
SJ

Mr Electric

well i disabled both because they dont supply the rx with power anyway
no i dont have a diffrent esc
i just tryed it again and it will still run both as per drawing !!(only ran very slowly to protect servo lead)