Reference book for advanced electrics

[Skygeezer]

Hi to the group. Its been a long time since I was on this forum. i fly electric mostly these days and am getting interested in larger models with multi engine installations. I have some basic electric aircraft books but am very disappointed in them since they are too basic for more interesting models. Does anyone have a suggestion on a book or reference that gives a good description of high power large model installations, and especially multi engine installations. I have my sights fixed on 4 engine WWII bombers.

Thanks

DonM

[Wheels]

Hi to the group. Its been a long time since I was on this forum. i fly electric mostly these days and am getting interested in larger models with multi engine installations. I have some basic electric aircraft books but am very disappointed in them since they are too basic for more interesting models. Does anyone have a suggestion on a book or reference that gives a good description of high power large model installations, and especially multi engine installations. I have my sights fixed on 4 engine WWII bombers.

Thanks

DonM

I don't think there's much much you need to learn about multi-motor or high power systems that you don't already know from smaller models... the parts and numbers just get bigger, especially the ones that come after dollar signs.

[Skygeezer]

For sure about the dollar signs. But there are things to know. I read in MAAC magazine about the demise of the big electric Lancaster, built from Tony Bingelis plans. It suddenly lost all power and crashed. The builder thinks there was insufficient redundancy in the electric system so one failure took it all down. High power multi-engine installations require different distribution and wiring. How do you use multiple batteries in both parallel and series? How do you talk to the receiver with 4 ESC's? What sorts of connection busses would you use and where do you get them? There is a lot to know, and I would like to learn.

[Wheels]

For sure about the dollar sig

ns. But there are things to know. I read in MAAC magazine about the demise of the big electric Lancaster, built from Tony Bingelis plans. It suddenly lost all power and crashed. The builder thinks there was insufficient redundancy in the electric system so one failure took it all down. High power multi-engine installations require different distribution and wiring. How do you use multiple batteries in both parallel and series? How do you talk to the receiver with 4 ESC's? What sorts of connection busses would you use and where do you get them? There is a lot to know, and I would like to learn.

Well... learn from that for a start. I'd never build a large 4 motor plane that relied on a single central pack... that would cause nightmares just trying to protect your ESCs from ripple currents alone.

I've learned first hand that large BEC's, even the expensive "bullet proof" variety, don't like being paralleled through a bat-share. You won't find many people flying large electrics that don't run independent receiver electrical, same as gas, with the aim of making sure that exactly that kind of problem never eliminates the possibility of at least a "deadstick" landing.

Sounds to me like what you want to learn won't be found in a single book, especially one aimed at the RC hobbyist, there's a great thread on RCGroups with a goldmine of firsthand experience with very large single motor planes.

http://www.rcgroups.com/forums/showthread.php?t=1142000

But in terms of a large multi-motor... I wouldn't worry about power busses because I'd only run independent systems for each motor and control system.

[Skygeezer]

That's a lot of batteries. You may need to combine batteries for more power and longer runs on each motor. I have seen battery boxes to do this. At some point you have to make all the ESC's talk to the receiver. You would power the receiver separately too I imagine but how do you provide receiver redundancy? What about powering the servos? You wouldn't want to make the receiver power a bunch of high powered digital servos. How do you power the servos separately? There are a lot of differences between an electric Northstar trainer and a bunch of Park flyers (my situation). And a 12 foot electric Lancaster (where I want to go). I don't expect forum members to have to explain basic concepts to me. Thus my search for
printed references.

[Wheels]

That's a lot of batteries. You may need to combine batteries for more power and longer runs on each motor. I have seen battery boxes to do this. At some point you have to make all the ESC's talk to the receiver. You would power the receiver separately too I imagine but how do you provide receiver redundancy? What about powering the servos? You wouldn't want to make the receiver power a bunch of high powered digital servos. How do you power the servos separately? There are a lot of differences between an electric Northstar trainer and a bunch of Park flyers (my situation). And a 12 foot electric Lancaster (where I want to go). I don't expect forum members to have to explain basic concepts to me. Thus my search for
printed references.

Much of what you're asking about are problems faced (and solved) by large scale internal combustion models. You may want to look into how they have solved these problems.

As far as battery banks go... yes, you will need to combine packs into series/parallel banks to power a single motor, combining multiple banks to power multiple motors offers no more power or duration than they would separately but it does come with many disadvantages.

To control multiple ESCs you plug them in just as you would multiple throttle servos... on slaved receiver channels or via Y-harnesses.

[JoeT]

No longer rocket science with the new fancy computer radios.

Things to note: Always power the receiver and servos from a separate power source when using multi engine planes.
Remove the "red wire" from all ESC's
Use 4 different channels all slaved to the throttle input to control individual speed controllers (This will give you tons of flexibility)
That way you can actually MIX some rudder with the throttles to help your ground maneuvering and have differential thrust if you want.

Using that method, you will not get and BEC feedback (no power to a common bus) plus redundancy if a motor quits as ruddering into the running engines will result in the automatic balancing of thrust if you want.

The sky is the limit, all you need are channels on the radio.