WattFlyer RC Electric Flight Forums - Discuss radio control eflight

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-   -   BEC for a Castle HV 85 (https://www.wattflyer.com/forums/showthread.php?t=45810)

kyleservicetech 06-07-2009 08:54 PM

Hi Jerry
That 18X12 is pulling a lot of current for that Eflite 90, so doing hovers might heat the motor up, so keep an eye on the motor temperature. But, flying at 1/2 throttle or so will cause that current to drop down to perhaps 20 amps or so. I've found that my Showtime with the Hacker A50-16S pulls about 13 Amps with just enough power to keep it in the air.

As for the A123's, as long as you have air blowing over that pack during a flight, they won't get hot. I've measured about 10 degrees above ambient after a flight with an infra-red thermometer. They get hotter than than that while sitting in the hot sun.

We are under overcast skies, with rain today. But last Thursday, I did some flying with my scratch build accelerometer in my new Great Planes "Revolver". Found that this model had "G" forces as high as 9.5 G's! And that was with just a normal loop. That's covered under another thread.

mofosheee 06-08-2009 05:50 AM

Hi Dennis:
Yes, the watt meter confirmed that my configuration of; batt's, esc and motor would be detrimental to these parts if I fly this like I do my gasser. With this I intend to watch my energy management.

I have also removed some balsa from the firewall and ultracoat from the bottom of the fuselage for cooling.

I assume that it is normal to see an electrical arc at the connection point when I connect the bat to esc and that this is normal.

Question is; for CG considerations, how far is your foreward battery pack form the firewall?

Please include a link to your 9.5 g monster that you refered to.


kyleservicetech 06-08-2009 05:39 PM

Hi Jerry
As long as you have openings in your fuse for air to pass through, you should be OK. It's a good idea to pick up an infrared thermometer if you have any questions. But, if you can hold your hand on the battery or motor for 20 seconds without branding yourself after a flight you are pretty much OK.

I've found my motors, ESC and battery packs are about 10 degrees F over ambient after a flight, putting them in the low 100 degrees F.

An electrical spark is quite normal when you plug in these high powered battery packs to the ESC. (These ESC's have large capacitors across their input circuit. The spark results from the near instantaneous very high current charging of these capacitors when plugging in.) Keep an eye on the connectors through. After a season or two of flying, these connectors can have eroded contacts. When that happens, its a good idea to replace them.

As for the battery location, they were split into two packs to balance the model. The first pack is just forward of the wing tube, the second is just behind the same wing tube. With your two pairs of 4S2P packs, its a matter of making the model balance properly.

That model will really be powered up, so don't pull full up elevator at full speed. Don't know just how strong that model is, but would hate to make a fuselage shaped splat in the ground while your wings go bye bye!

Below is the link to the acceleration thread.

mofosheee 06-08-2009 06:05 PM

Good morning Mr. Man with answers:

Yes I have Fluke and will be aware of temperatures. Fuselage is well ventilated though. My intension is to go quite easy on the entire set-up until I get comfortable and not to over; amp, heat, stress (or what ever)

The arcing of the contacts from charging capacitors makes sense. No way to eliminate this.

Looks like one of my packs will be right close to the firewall, the other just behind the wing tube.

As you advised, limit my first flight to 4 or 5 minutes and not to fly it like my gasser.
I briefly looked at your acceleration thread last night at work. I'm not sure that I want to know what the g's will be. It could be scary.

Thank you


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