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

[fhhuber]

We used to use "Shotkey Diodes" on brushed motors to deal with the spikes.
But even high speed of a Shotkey is not fast enough for the high switching rate of a brushless ESC.

https://en.wikipedia.org/wiki/Schottky_diode

[Hardway]

We used to use "Shotkey Diodes" on brushed motors to deal with the spikes.
But even high speed of a Shotkey is not fast enough for the high switching rate of a brushless ESC.

https://en.wikipedia.org/wiki/Schottky_diode

I just used the data logger function from my test ESC and the ripple voltage with the 44 inch lead was only .75v @ 25.2V dc. The average was .19v.... So a 10 percent variance would be 2.52v DC.... So with the extra in line caps, the shorter leads (16.5 inches), and the longer motor leads, this should be all good! Do you all agree??

[Hardway]

Also, with the 13x12 3 blade, the data logger shows 71.3 amps max and 1617 watts at 8401 RPM. So there is enough power there!!! :Cool: I think the prop is loading the motor and ESC just about right...

[Hardway]

Just check the next ESC that I used for the thrust test reading with the rig and fish scale... At 25.2v dc and NO lead extensions, the Ripple was .49v dc.... So,,,,,, wow... Thoughts????

[Hardway]

Well, I did finally get the courage to cut the top hatch. Was going to do that two days ago, but I kept finding other things that were easier and safer to do!!! Pics to follow after I have a beverage to settle the nerves... LOL

[Elbee]

...after I have a beverage to settle the nerves... LOL

Hrdwy, I am having a sympathy/congratulatory beverage with you right now. Cheers mate! LOL:Smoking: Best, LB

[Hardway]

Cheers!! It is 5 o'clock somewhere!!!

[Hardway]

I outlined the "hatch" with frog tape to give me a reference to guide on... Then a deep breath (through my respirator) and the cutting began... I am fairly happy with the outcome... It will make things a ton easier for maintenance and battery changes, etc...

[Hardway]

Without the tape...

[Elbee]

... It will make things a ton easier for maintenance and battery changes, etc...

Hardway, are going to reinforce around the wing saddle area? Obviously, you'll develop and build a hatch securing method which will reinforce it somewhat. Just wondering about your thought process here. Best, LB

[Hardway]

It doesn't look it, but the fuselage is incredibly solid and stiff... The entire Westcraft fuselage has no formers except for the tail wheel gear and the wing mounting plates at the front and rear of the saddle... That is why I was very careful where to cut so as not to destroy the built in fiberglass "rings" that are structural... But, I always over-build stuff, so YES there will be some plywood and carbon fiber "helpers" JIC....

[Hardway]

After looking at the pictures again, it does look like you could just flex the entire fuselage. I went back and tried to twist it with a good amount of old-man force!!! LOL Didn't budge. The fiberglass in the actual wing saddle/fillet is very, very thick. Better than a Corvette fender!! Seriously... :Whew:

[fhhuber]

I just used the data logger function from my test ESC and the ripple voltage with the 44 inch lead was only .75v @ 25.2V dc. The average was .19v.... So a 10 percent variance would be 2.52v DC.... So with the extra in line caps, the shorter leads (16.5 inches), and the longer motor leads, this should be all good! Do you all agree??

Note that the spikes will be higher at high load mid-range throttle. Its hard to predict the highest. The ESC is most likely to survive marginal input capacitors at full throttle (or motor off)

Exactly what peak is max the ESC can survive? You'd have to ask the maker. Castle ESC label values are typically WAY under what the ESC can survive. While its not generally recommended to exceed the labeled ratings, what some have done with Castle ESCs and gotten away with is impressive.

[Hardway]

Roger.... I was running the motor at 1/2 to 5/8 throttle in one minute intervals to see how the battery life would hold up.... So with shorter battery to ESC leads, the caps, and longer motor leads for the outboards, do you think it is a safe setup to use? Thanks so much for your input!! :Cool:

[Hardway]

So, I decided to install the new top turret and ring. The one that came with the model was just way too tiny... Like 1/16ish-scale on a 1/10th scale... LOL...

[Hardway]

First thing... The ring was designed to fit a B-25, so Mr. Dremel and me had some fun. Then the belt sander. Then the orbital sander. Then 320 grit wet and dry paper... :Whew:

[Hardway]

Next, cutting the hole in the top hatch for the turret ring... No stress here. :Sweating:

[Hardway]

So, it all came out OK. Have a few tiny little bobbles to fill with body putty, but overall, we have a functional top turret. A servo will move her around and the machine gun bursts from the sound system will finish it off... :P

[boomer108]

Nice work Hard way!

[rifleman_btx]

Looks great! I think you will make it!