To say I am a newbie when it comes to electrics is a gross understatement, conversely I have been flying glow off and on for over 20 years.

Now that that is out of the way here is my question. I have a Royal B-17 kit that i started YEARS ago. so far only the wing is built but not sheeted. I do not have any desire to worry about keeping 4 glow engines running and want to put electric in. My question is not the usual what size engine but rather how to install 4 electric motors.

Can everything but the motors be put inside the fuselage?
What wires do I run in the wings?
Do i put batteries in the wings?
I want to build most of the plane without the engines so i want to prewire.

Thanks for the help

There's a little info at
http://www.rcgroups.com/forums/showthread.php?t=12004
Joe Beshar had his electric B-17 at the NEAT Fair for the last 5 years or so.

From what I have seen and experienced, twin engined electric is no more reliable than gas, it's just much quieter.

For example, twin electric motors:

They will not operate from one controller, so, you need two separate controllers tied together with a Y harness. That is, unless you read the technical info with your advanced controller, and find that you can use separate channels for the throttle.

When you use two controllers, there is no guarantee that they will operate exactly the same. In other words, when you spool up the motors, the RPM curve may be different. What does this do? It means that the take off run will not be straight, the plane will veer opposite of the faster motor.

In flight, one controller might shut down sooner than another and you will have an in flight emergency you will have to kill the remaining motor and glide in. Now, if the field is noisy, you will not hear this until it is too late.

Why does this happen? It happens because the components are not manufactured according to precise ISO or industry standards, and the finished circuit board components have a variance in specifications. Each controller is slightly different.

Given these negatives, and the negatives of gas motors, electric wins. But electric does not win out because of reliability, electric wins out because of many other considerations, such as noise, mess, and environmental damage.

Al Gutkin

You are grossly mistaken as to the reliability of electric motors. I have had hundreds of electric flights and have had exactly 2 dead stick landings which were attributed to motor problems and both landings were non-issues. Get your facts straight because someone may believe you know what you are talking about which you don't when it comes to electric flight!

I don't know what I am talking about? Man, I am trying real hard to hold myself back from really talking about your ability to read and understand reading material. However, all ages and mentalities frequent this web site which sometimes is good, and in your case............, you completely misread my post.

The subject was not about motors being unreliable, I spoke of controller reliability. In my opinion, the combined twin controller and motor combination is not more reliable. The key word is "Controller" Just in case you missed it..."CONTROLLERS ARE NOT MANUFACTURED UNDER GOVERNMENT OR SPECIFIC INDUSTRY QUALITY STANDARDS" That is what I am saying. Put two controllers in an electric twin and you may not get the same performance from each motor. It's the controller, not the motor. Any person educated in electronics or electronic component construction will verify what I said. Cheaply made electronic components are not made according to strict quality control standards, and some end up with un-acceptable variances, but, non the less, are still assembled in your controller's circuit board.

For reference about the reliability of twin controllers, all you have to do is read the Transall C-160 thread on this web site. Or, as a matter of fact, read any of the twin electric conversion threads. Better still, why don't you read Greg Covey's threads also in this forum. He is somewhat of an electric conversion expert. If you can count to three, that's how many faulty controllers he went through with one of his more recent conversions.

You said that you have flown hundreds of electric flights with only two failures. Great, how does that make you an expert on twin engine gas to electric conversions. Now, here is what to do. Go out and spend some of your dads money and buy a 7lb or more gas twin. Get a kit, no ARF for you, take months to make it. Then convert it to electric and fly it immediately upon completion. Better still, don't learn the hard way, fully test it on the ground first. Monitor the performance of each motor with duel amp meters, test the RPM of each motor in while you spool them up. You might find a slight difference in the linear RPM curve of each controller, don't worry, fly it anyway, I love to see RC planes taxi off the runway because of un-even prop speeds. In some cases they actually spin in when one reaches max RPM before the other, or when one of the two controllers shuts down for no reason. In any case, I personally think you are really misguided in your response and your insult will be remembered. Please subtract one worthless post from your post count and if you were half a man, I would expect an apology

Al Gutkin

You can live in your little dream world and I will continue to fly my 21 electric powered planes including twin engines planes,1 DLG, and 1 helicopter. By the way, I am 59 years old and pay for all my toys.

Who gets the last bad word without getting kicked off this web site? Tape is over my mouth....LOL

Dream world? Yep, you are right on. I have done stuff other people dream about.

Personally owned and flew a total of over 30 full sized warbirds, twins and high performance singles. Rated instrument pilot, multi engine, land and sea, and have been flying RC for the same 20 years as the full size. I personally wired nav and comm radios, constructed and installed my own custom instrument panels in full sized aircraft, never a failure. I know what I am talking about when I discuss the variance in electronic component construction.

I also went to school and actually graduated. I can read, understand what I am reading, however, I can't spell without a checker. If you can spell you win, however, with the rest you can say what you want, but we all know who is right.


YOU ARE WRONG AND OWE ME AN APOLOGY.

Al Gutkin

PS you responded to a post that I was in the process of changing. I made it softer, less insulting. I was to harsh.

Ummm...

While this maybe fun can we get back to my question? And for the record i'm 41 years old and my Wife LETS me pay for all my toys.

Yes the purpose of this thread is to provide information.

1. Is electric better....we argued that one to death. Yes and No. The preference nowaday is electric, noise, environment, and for single engined aircraft, electric is usually more reliable.

2. How to wire your plane during construction. This question cannot be answered with certainty. The reason, is that most model builders, including ARF builders, have their own methods and ideas. In addition space and cooling is a major consideration. Regarding your B17, the motor controllers might fit in the engine necelles, but the batteries are installed in the fuse.

3. The electric motors are hooked up with three wires, red, black, and white, which connect it to a specific controller. So, To be safe, you need three 13 gauge wires from each of the engine nacelles to the fuse. If you mount the controllers in each engine nacelle, you will only use two of those wires. The two 13 gauge wires go to the battery pack from the controller. In addition, each controller has an additional connection that goes to the radio receiver, so you will also need servo extension leads running inside the wings to connect each controller to a Y connection, then into the receiver, which is the throttle control. Now the question arises, how to power the receiver You can use the typical nicad pack or you can use the Lipo batteries that power the motors. If you want to eliminate the nicad receiver power pack, you then must wire in something called an SBEC. This small circuit has two wires that tap into the Lipo battery wires and run to the aircraft's on/off switch. The SBEC provides power to the receiver and servos, even if the controller shuts down the motors.

As far as a wiring diagram for electric, you can find all kinds of info from Fmadirect.com, of from Greg Hovey's web site.

How does the system work? The electric motors are controlled with controllers. Some controllers are sophisticated and actually can be programmed to change the timing of the motor, and also stop the prop from turning by using a breaking mechanism. The controllers get thier throttle commands from the radio receiver and pass it on to the motors.

The weakness in the system are just a few. Since each motor has it's own controller, the controllers must match in size and performance. Cooling of the controller and batteries are also a consideration. The best bet before starting to close up your wings is to spend lots of time reading. If I were you I would find a post by Greg Hovey, follow the link at the bottom of his post back to his web site, read the reviews on each of his conversions. You will then get a clear picture of what you need to consider.

Summary:

If the controllers are in the fuse. Three 13 gauge wires will be needed, to run from each nacelle to the fuse, then into the controllers. They should be made to unplug from the controller when you remove a wing. The controllers usually come with these connectors.

IF the controllers are in the engine nacelle. Two 13 gauge wires run from each controller to the fuse, they are attached to the battery pack. They should be made to unplug when a wing is removed. In addition you need to run servo extentions from each controller to the fuse. They plug into a Y connector.

Hope I helped
Al

You wonder if you helped?

Only thing lacking in that post was the pictures!

Exactly what i was looking for. Thanks ever so much for the help.

I made a mistake in the spelling of Greg's name, typo error. Rather than going back to edit a previous post here is the link to his web site.

http://www.gregcovey.com/rc.htm

better still.

http://www.gregcovey.com/Glow_Conversions_Made_Easy.htm

When I considered the nitro or gas to electric conversions I felt like a fish out of the water. I instantly knew that the considerations were not simple, like following a schematic and soldering a wire from point A to point B. Reading Greg's conversion reports was a great start for me, the pictures and videos can't be beat. Greg is the engineer type of personality, however, his articles and responses are fabricated for the layman to understand.

You will become an expert in no time. What I have learned from experimenting in the electric conversion process is that we all become research and development engineers. We can emulate someone else's project, or use math programs to enable the sizing of motors, props, and controllers, but all that does is get us into the ball park. The rest is up to our own trial and error. With a project like the B17, I would test out the motor controller configuration project first on the work bench. Make a wood fixture to hold each motor and run the setup like it was in the airplane. That way you can test it under a controlled environment for controller failure under load. Twin electrics are not bullet proof. I have a B25 ARF kit sitting in the garage, however, based upon my experience with electric twins, I'm letting it sit for awhile longer.

Al

Regarding similarity of controllers etc: If you build a multi motored plane, buy all the motors at the same time from the same source. The mfrs do change things in the motors from time to time. Buy all controllers the same way for the same reason. Buy Castle as you can put the same software version in all of them. Castle has a great tutorial on their site that gives many recommendations on seting up multis. You may not need a separate battery eliminator circuit. Castle controllers have ample BEC's up to 3S (12V battery) and you can combine the BEC's when you 'Y' the throttles together.
SBEC is a brand name as is UBEC. They are switching power supplies that convert the high voltage of the motor battery to 5 or 6V for your radio gear. koolflightsystems.com has a way to use 2 UBEC's for redundancy.

I built a twin and used most of Castle's recommendations. It is like an F-82 (twin Mustang) but is made of 1.5 Stevens Aero CAP 232 kits. The fuselages are about 24" apart and so I elected to have no interconnections. That's right, 2 batteries, 2 receivers, etc. Works great. The motors almost always sound in synch. I never notice any yaw from differential thrust.
I believe that if you are careful and use a tested system (mine is the same as what is in a single CAP) you won't have any problems.

My biggest concern is LVC (Low Voltage Cutoff). Controllers are usually programmed to stop the motor when the battery voltage drops to a certain point so it is not over discharged. This keeps you from accidently ruining your battery. You can disable this feature if you want. I think it is a much better idea to use your Tx timer so you don't fly more than 60% of your charge.

Default LVC on a Castle controller cuts off the motor at the designated voltage. Once the motor is cut off, the battery voltage rises and you can run the motor again by throttling to idle then back up. There is also an option for 'soft cutoff' where the controller slows the motor so the battery voltage stays above the minimum.

You have several advantages by the model you have chosen:
It has a relatively low wing loading
It is a kit so you can substitute wood to make it lighter - you won't need hardly any plywood as there will be little vibration.
It is 4 engine so the loss of an engine won't be as severe as a twin.
It is a bomber so you should be able to find lots of room for batteries.

I'd try to put the batteries in the wing/nacelle if possible. The pain may be making hatches to remove them.

Lastly, I am a full scale pilot. Other than a basic understanding of aerodynamics, it doesnt help much in flying RC. It can hurt if the individual is not humble enough to understand this.

Feathermerchant,

You did and excellent job at filling in some missing info. and also helped in the understanding of how the exectric mechanics go together. However, you have loyalty to Castle, I have loyalty to Jeti and Axi motors. As per my readings on this web site, Castle controllers fail and so do Jeti controllers. I sent back a batch of 5 40 amp Jeti controllers when my twin C47 spun in and I later found that the 40 amp controllers were not up to specs. I tested the crashed controllers on the work bench and tested the others that were already removed from their wrappers, all failed at much less than 40 amps. Greg Covey just experienced 3 Castle Creation controller failures, you would think that at least they would send him a good one, as he was working on a aircraft review.

This is the game, research and development. I have a freak of nature in my C160, two Axi 2820 motors running off of one 70 amp. Jeti controller. They said it wouldn't work, it did, but, I can't duplicate it.

Take care

Al Gutkin

See one fly : http://media.putfile.com/Second-Flight-B-17

This one flies with two AXI 2808/24 inboard and two Park 480 out board. Master Airscrew 9/7 3blade pusher/tractor outboard counteroating. Motors controlled by four Pheonix-25 speed controllers and Thunder Power 8000 3 cell.

Algu... Thanks. Hope I answered some questions.
I have yet to have a Castle controller fail on me in the air. I had a Jeti on an AXI that failed (AXI failed) mid flight and it caught fire. When an AXI failed on a plane with a Castle, it would not start but the controller did not catch fire. There was at least one problem with the HV controllers because they tried to eliminate the spark at plug-in with some hardware and software. The failure mode was that the controller went dead. They have removed that and retrofitted all controllers sent to them. I have seen large AXI motors have trouble when run by Castle controllers. Castle tells me it has to do with how the motors are made. ie magnet position, winding accuracy etc. I read about Greg's problems and I wonder if thats it. I have had no probs with Hacker (C50XL on 10S ~50A on a 45HV) and I just ran up a Hyperion 4035 on 8 and 9S at up to 65A on a Phx 45HV. I won't fly it that way but it did work. I've run Phx 45's at 45-50A regularly on 3S and even with 4 HS-81/85's they work great. My 10's see 12A with no problems, I have a 35 in a ducted fan (Mega 16/15/2) that pulls 45A. I really should replace it but it's been flying 2 yrs now...

Anyway, the Castles are more programmable than any other. That's why I recommended them. They're the only ones I know of that you can be sure what the software version is.
This bomber project should be easy to build very conservatively so it is absolutely reliable. In fact I have a Tritle designed B-17 kit I should start soon. It's ~60" but only 4lb so 4 outrunners on 4 Phx10's should be great.

I wonder how much the Royal B-17 will weigh.

dyno - thanks for the post. Looks like it has plenty of power.

My Royal B-17 AUW is at 10lb 11oz; i might add that with 9" propellers there is very little clearnce between prop tips and fuse; so I trimmed the props to 8.5". This also keeps the peak current per motor under 25 amps.

I am doing an electric conversion on a CedarHobbies.net B-17. This one has a 78" wingspan. AUW when using .32 Magnum 2-stroke engines was 12 pounds. With electric, it will be significantly lighter(I hope). Anyhow, I am using 4 x E-flite Power 10 outrunners. I haven't bought the esc's yet, but had originally planned on using 4 - E-flite 40 amp esc's. The props are MAS 9x7 3-blades. I haven't decided on using counter-rotating engines/props as the real plane did not have that, but I am still open to the idea. I have an FSK B-25 that does have counter-rotating props/engines on it since there is no functionla rudder.

AS far as electronics in the B-17, I will eb wiring all the esc's up using Y-connectors, but disabling all but ONE BEC(using 3 inch servo extentions and cutting the red wire). For power, I am using 4 or 5 TP 2100 3s lipos connected into a FMA Direct circuit board with 5 Deans connectors on it.

I am aware the B-17 did not originally use counter rotation; however, it is so easy with electric and makes takeoffs much more pleasent. Per Castle Creations it is not necessary disable BECs as they work just fine in parallel. I also have one of E-Flight's Super Airliners with two of E-Flight's 20 amp controllers in parallel; no problems so far. With the Castle speed controllers in parallel it provides up to 12 amps for radio equipments; I like a bit of overkill.

Learned...
I have the same Royal b17 which I picked up partially built. Its not on the bench yet and the cue to get on is pretty long but, its time is coming. I'm pretty good with electrics and multi engines/motors. I have only a few years of flying RC but I'm a poor covering artist. I'd be glad to try to help you with the electric questions if you'll stand by to help me when I tackle my Royal B17. One thought as you assemble the pieces. Brushless outrunner motors need their own dedicated ESC. That's one ESC per motor--no sharing! Brushed motors don't have this problem. They can share and ESC as long as the supply wires are very close to the same length so they get their power and instructions from the ESC at about the same instant. When I looked at the kit I was thinking that each nacelle would have a separate Brushless outrunner, its Esc and its battery probably a ThunderPower 11.1 volt 3s2p 2100 mAh pack. The ESC controllers each have a receiver connector and these would be the junction point where all four ESC's come together and go to the RX.

Yes LaxLife...pretty accurate. Although, you dont want all 4 esc's trying to power the receiver and servos or you'd cook the parts. Some esc can work in parrellel, but not in a quad set. So, this requires disabling at least 2 of the BEC's. Dynaflux....yeah Castle Creations say they can run in parellel, but a 45 amp esc(the size I would need from CC) cost $109 each. Whereas the 40 amp esc from E-flite costs $54 and matches the motor(since its an E-flite as well). In my case, I do have to disable some of the BEC's. I am however, also installing at least one switching mode BEC(aka ParkBEC: http://www.dimensionengineering.com/ParkBEC.htm )in order to run more servos.

I myself am not placing the batteries in the nacelles, but will be placed in the fuse under the removeable canopy area for easy access. This is why Im using that FMA direct circuit board thing to connect up all batteries so all engines can pull from all 5 batteries so I dont have an engine cut out on one side of the plane and not others. Of course.....dont want to fly long enough to reach LVC either.

Here is a pic of my Cedarhobbies B-17 in progress. Covering it with aluminum foil tape. I am not claiming I am the best detail person either, but it looks ok. I will be adding rivit lines once the plane is fully covered(aluminum foil with dimple marks using a dressmaker's wheel).

Sorry for my last post I typed !QUOT!disable ESCs!QUOT! instead of disable BSCs; I edited the post to correct my error. I have some experience with multi motor electrics all except one are still flying. The only one not operational at this time is a GWS A-10 which was a casualty of massive stupidity on my part (ailerons backwords.) A list of my multi motor airplanes.
_
Kmp P-38 with two AXI-4130s powered by 8s4p Thunder power lipos and Phoenix-85 HV speed controllers
JR (Hobby Lobby) B-25 with two AXI-2808/34s powered by 3s4p Thunder power lipos and Phoenix-25 speed controllers
Guillow P-38 with two Himax 2808/1160 powered by 3s1p Thunder power lipos and Thunderbird 19 speed controllers
Hobby Lobby Cessna Skymaster with one Himax 2808/960 and one Park-450 powered by 9 nimh 1700 and Phoenix-25 speed controllers
E-flight Super Airliner with two E-flight ducted fan 400 outrunners powered by 3s2p Thunder Power lipos and Eflight 20 speed controllers
Royal B-17 with two AXI-2808/34s inboard and two E-Flight Park 480s powered by 3s4p Thunder power lipos and 4 Phoenix-25 Speed controllers
GWS A-10 with to Himax 2015/5400s powered by Thunder Power 2s1p and Thunderbird 19 speed controllers
_
With the b17 I used one battery pack to power all 4 controllers/motors. I used #12 wire from the battery to the inboard motor/controller and #14 wire from inboard to outboard. Use high quality silicone wire as it will not melt if you over current it. Never fly the airplane to the point of low voltage cutoff due to wire, connector, and electronic component tolerances one speed controller will always quit before the others. I start with short flight and measure the amount of power left in the battery; in about 3 flights you will be able to find a safe time limit for your flights.

If you use E-Flight speed controllers it may be a good idea to contact Horizon and ask for advice about parallel connection of BECs. Castle Creations use standard voltage regulator circuts on their controllers; since this the also the easiest solution E-flight may do the same making parallel BECs ok. With my E-Flight Super Airliner the instructions advises to connect speed controllers with standard Y connector; no mention of disabling one BEC.

Nice fleet of planes

Effectively, I will also be using one battery(at least the esc's will see it as one battery since 5 TP2100s will be set up in parrelel). So, you basically wired all your esc together(the battery connections) and then simply y-connected the throttle leads? Wouldnt that overvolt the receiver and servos?

Most speed controller BECs output regulated 5 volts for receiver and servos; if they are connected in parallel (standard Y connectors) the output is still 5 volts. The only problem that could arise from parallel BECs is when output voltages are not close enough to each other causing regulators to fight each other to try and maintain their output voltages. This the same reason you would not parallel two batteries with different battery voltages or levels of charge.

Ok, well in this instance, then unless an esc is spcifically labled as capable of working in parellel like the CC's, then I'd have to assume they would not work anbd would fight against each other unless BEC wires were cut on at least 2 out of the 4

There is a way to test parallel BECs if you have access to a good ma meter. Using two speed controllers attached to the same battery (in parallel) remove the red wire connector from the housing on one of the controllers and Y connect both controllers and plug into receiver. Turn on the transmitter and connect the battery while measuring the current draw from the battery. Now reinstall the red wire connector into the housing and repeat test. If current changes more than a few ma the regulators are fighting each other and can not be used in parallel.
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One other option; On my B-25 I built a custom wire harness that seperated the positive leads as follows. One BEC powered the receiver, ailarons, and elevator; the other BEC powered the rudder, landing gear, nose wheel servo, and bombay servo. This was not needed with my CC controllers but I did not know they could be paralleled when I built the B-25.