Electric Stunt > Gettin all AMP'ed up!
Electrocuting the Atlantis
Tim Wescott:
Well, it's getting a Badass 2826. Last time I installed the motor as close as I could to the front, cut off the end of the shaft, and sacrificed some cooling. This time out I'm installing the motor so that the "stock" shaft length puts the spinner where I want fore&aft -- that moves the motor back about 3/16 of an inch. I'll work on the cowl to get some air in there.
Also, last time out I routed the air so that it just sort of blew on the bottom front of the motor -- there was a baffle in there so that any air coming in had to go through the motor, but clearly it wasn't effective enough. This time there's, like, holes. I'll probably do some flights with the spinner off, then compare-contrast the motor temperature with spinner on and off.
I won't be getting appearance points for it, so aside from some inevitable comments from Paul if I make it too ugly, it's not like I'll lose anything if I bias the the cooling vs. looks fight in the direction of lower temperatures.
Tim Wescott:
My usual go-to clamp when nothing else works is tape. Someone, however, has apparently waxed this airplane a bazzilion times, not to mention letting a motor slobber castor oil all over it. So things are wedged in place with balsa, matchsticks and (yes) Q-tips.
It'll hold until the glue sets. Unless a moth lands on it. A mouse running over it would definitely upset the thing. For a mount that was put in place by fittin' and filin' the thing fits pretty good. I'm just lining up the spinner to the front of the fuselage -- it's offset about .02" to inboard, but I think I'll accept that (no appearance points!)
Tim Wescott:
I added an outlet just for motor air, and I managed to fly yesterday and today.
With just the outlet, the motor was cooler than the Cobra, but still hot enough to be worrisome. Based on advise from Paul Walker I added some NACA-ish inlets to the side of the cowl, blowing on the motor. While I was adding the inlets, I noticed that I had failed to modify the baffling from the existing front scoop to match the new motor position -- so I fixed that, too.
This brought the motor temperature down to somewhere in the neighborhood of 50C. This is according to a phenomenally cheap Harbor Freight thermometer -- so I'm not sure I believe it. But the measurement is backed up by calibrated fingertips -- I can touch the motor and hold my finger on it, which is about 50C. Moreover, it starts cooling immediately after the flight, where the Cobra would continue to heat up on the outside of the motor, indicating that it was _really_ hot inside.
I decided that my attempts at NACA inlets were ugly, so I made metal covers for them. Hopefully these will generate even more airflow over the motor -- and they'll definitely cover my woodworking sins. More testing as I get a chance. I'm hopeful that I can start actually practicing flying with this thing, rather than just piddling with the power system.
At this point I'm going to do a few more test flights to check temperature, then start actually flying. I have a spinner that Howard Rush made for me to fit my backplate, but I haven't yet assembled it. I'm a bit concerned that it will block some of my cooling air, so when I do get that done I'll be testing it, and then I may end up making some holes in it for airflow.
I did expect that I'd have a learning curve switching to electric. I did not expect that it would be this steep and this high at the beginning!
Dennis Nunes:
--- Quote from: Tim Wescott on July 25, 2021, 05:52:27 PM ---I did expect that I'd have a learning curve switching to electric. I did not expect that it would be this steep and this high at the beginning!
--- End quote ---
Welcome to the wonderful world of electric power! LL~
Dennis
Tim Wescott:
--- Quote from: Dennis Nunes on July 25, 2021, 06:31:38 PM ---Welcome to the wonderful world of electric power! LL~
Dennis
--- End quote ---
;D
I was telling someone that those scoops look they're on the "C" model of some WW2 fighter. The "A" model had overheating problems so they stuck the scoops on so they could stay in the fight. Then by the time they get to the "E" model they've revamped something else, and either fixed the underlying problem or built those scoops into the "real" cooling system.
The battery and ESC is as cool as I could ever want -- and if you look at the original scoop, you'll see that horizontal divider -- the top goes to the motor, the bottom to the ESC & batteries. So you can see that maybe a revamped cowl would have a different dividing line, and maybe more area.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version