1/10th Scale Westcraft B-17G Electric Conversion

[rifleman_btx]

Maybe run some kind of ducting from the waist gunner positions? Just thinking of other options if possible.

[Ole-Timer]

I had also considered what fhhuber described but never actually did it or tested it. Remember the air intakes on the leading edges, the bomb bay, and the waist windows as an exhaust.

[fhhuber]

The batteries near the ESCs have to be large enough to survive full throttle for a short time without the main packs connected when using that method to deal with the inductive snap issue.
I'll need 50C + rated packs.

[Ole-Timer]

If it were me, and I had no other immediate resolve, I’d stick the esc’s in the bomb bay, perhaps with telemetry to monitor heat and use the doors to let cooling air in. When you have more time over the winter to alter the airframe I’m sure a better solution can be achieved.

[Elbee]

Hrdwy, would be too much work at this point to put the ESC's on the bottom of the nacelle with a vent screen or perhaps between wing rib structure on the bottom side close to the leading edge? Don't know the wing construction here, just thinking how I might resolve this issue. Best, LB

[Hardway]

I think I may have a solution that will work... The inboard nacelles are open on the bottom because that is where the retracts and wheels live... I am going to bore a 3/4 hole from the bomb bay to the inboard nacelles. This is a direct route for the wires. I am going to locate both ESC's for port and both ESC's for starboard in their respective inboard nacelles. I have space to separate each ESC from one another so air can flow freely around them. The air will be from the prop and ram air from forward flight.... Then the outboard motor leads will not be too long, and the ESC to battery connection will be shortened substantially... I will go measure the battery to ESC distance... Stand by... :Confused::Cool:

[Hardway]

This looks very promising!!! By redirecting the cables, it cuts the length of the leads from the battery to the esc to 16.5 inches!!! I just measured the ones in my Freewing A-4, and they are 18 plus inches from the battery to the ESC!!! So what do you all think about that?? :Thinking:

[Ole-Timer]

That’s much better, did you get any info from Castle?

[Hardway]

That’s much better, did you get any info from Castle?

Thanks!! I have not contacted them yet. Been really busy this AM... I will try after I get lunch done!!! I am much happier with the 16 inches. The CC ESC has really short leads out of the box, so I am guessing CC expects some extensions...

[Hardway]

Hrdwy, would be too much work at this point to put the ESC's on the bottom of the nacelle with a vent screen or perhaps between wing rib structure on the bottom side close to the leading edge? Don't know the wing construction here, just thinking how I might resolve this issue. Best, LB

Thanks!!! Great ideas... Working in that direction. I will put in baffles, if necessary, to direct air on those ESC's in the inboard nacelles... Can't do the LE locations. One of the main spars in the foam core wing is very close to the LE... That would only save a few inches on the wires anyway... Have a great afternoon LB!! :Cool:

[Hardway]

OK, now comes the point of no return.... I am going to cut the hatch in the fiberglass fuselage. I am going to tape off the outline and use the finest cut-off wheel I have on the Dremel and a Zona razor saw to do this surgery. I figured I better knock it out now before Happy Hour!!! :Sweating::Drinks:

[Hardway]

That’s much better, did you get any info from Castle?

I sent them a support request. Here is the basic data they just received. I have to use an extension from the battery to the ESC. I am using 10 AWG wire from Motion RC. What is the longest safe length that the Phoenix 100amp ESC can handle?? I think I can limit the length to approx. 17 inches to reach the inboard nacelles on the B-17G. Thanks for your prompt response!!

[rifleman_btx]

I really feel like itll be good to go. Just about all the new pnp twin engine planes have pretty long leads from the battery to the esc. I'd venture to say around 13 or so inches. Since I never had a chance to fully measure them

[Hardway]

These are the old (since 1989-90) servo mounts and battery platforms that I removed to start work inside the beast... yuck....

[Hardway]

Here is the new lower hatch. I wanted to try this one out before I took the plunge for the huge top hatch. It worked out well... ;)

[Hardway]

I sent them a support request. Here is the basic data they just received. I have to use an extension from the battery to the ESC. I am using 10 AWG wire from Motion RC. What is the longest safe length that the Phoenix 100amp ESC can handle?? I think I can limit the length to approx. 17 inches to reach the inboard nacelles on the B-17G. Thanks for your prompt response!!

Still nothing from Castle Creations... They need to learn a few things from Motion RC support.... :Straight-Face::Thinking:

[rifleman_btx]

There are a few companies I've been saying that about for a while. :Thinking:

[fhhuber]

The basics of what happens.

https://www.electronics-tutorials.ws...ppression.html

The long wires act as an inductor. When current is switched off, there is a reverse-current response known as an inductive spike.
The MOSFETS in your ESC are rapidly turning on and off current flow, causing thousands of inductive spikes per minute. The longer the wires, the bigger the spike.
The input capactors on the ESC are there to absorb the expected spike based on the expected wire length. (typical wire on the battery + what came on the ESC + a 50% margin is what is normally expected)

Adding 50% to the length between ESC and battery... probably not a problem.

Adding more than double and you can cause the input capacitors to explode, or just fail with the MOSFETS catching on fire.

http://www.castlecreations.com/en/cc...ck-011-0002-02
Use one added capacitor bank per 8 inches added wire...

[mr.frankenjet]

Castle makes these cap packs to help with long battery leads, I believe they need to be close to the esc to be effective

http://www.espritmodel.com/castle-cr...e-cappack.aspx

[Hardway]

OK, the capacitor packs are ordered 2 day air... Thanks guys! :Cool: