xb36
Posts: 221
Joined: 2/15/2008
From: White Bear Township,
MN, USA
Status: online
|
John,
My rationale is this for using 6 small LiPo battery packs.
First, MotoCalc indicates that running thse 6 motors on one pack would cause it to over heat.
Second, I know of a 17 foot span B-36 with glow motors that crashed because the left outboard and left middle motors died during flight. The plane became too difficult to control. My original plan was to use one battery pack to power the left and right outboard motors, a second battery pack to power the middle motors, and a third pack to power the inboard motors. That way a battery pack issue would cause a balanced power loss. I could tolerate the loss of any pair of motors (inboard, middle, outboard) so long as the problem didn't occur on take off.
I could use only 3 LiPo packs and use one pack per motor pair, but the LiPo pack would run warmer and I didn't see a weight reduction by going to 3 packs. You also mentioned that 6 smaller packs MAY be easier to position in plane as compared to 3 packs. The decision to use 3 or 6 packs can be delayed up to the last minute.
You also commented about the location of the ESC's. I had that same concern a couple of weeks ago so I posted a thread in the Brushed/Brushless, Speed Controls, gear drives forum. The post was titled Long ESC wires or long motor wires?
There was a reasonable amount of response and the outcome of the thread was that you should keep the battery leads to the ESC short and allow the motor leads to go long. That recommendation is listed in the manual for a couple of the ESC manufacturers.
Even so, we have to now consider that you have done the reverse and put the ESC close to the motors with longer battery wires. And, you have done so successfully. I agree that allowing the air to pass over the ESC is a good move and you will get more air flow out by the motors. Well now I don't know what to think. I thought that the thread had cleared up that decision. If you don't mind, review the thread and let post your comments.
I must admit again that I have not used LiPo cells. I understand that they must be left to cool completely before recharging and then using them in flight. Although pricey, I expect to purchase another set of cells if this configuration works out. With a second set of cells, I could go out to the field with 2 sets of fully charged LiPo packs. The price keeps dropping so a second set of cells becomes less expensive as time goes by.
No one seemed to concerned about the length of the signal wires to the ESC except me. With a large wing, there had to be some long wires somewhere. I was concerned about picking up too much radio noise. My solution is to purchase a new JR 9303 radio with the Spektrum multi receivers. I think I saw a Spektrum setup using a total of 4 (or was it 3) receivers was around $235. If that stops this plane fron going down due to radio interference then that is what I will do. Go to www.youtube.com and watch the B52 nose in due to radio siglnal loss. All of a sudden the cost for the radio doesn't seem so bad.
Well, that should answer all of your comments. Let me know what you think. Comments from others are always welcome before it gets too difficult to change something so throw your comments in now.
Mike Roerig
mikeroerig@gmail.com
|
Printable Version
All Forums >> RC Airplanes >> RC Scale Aircraft >> RE: B-36 build thread and free plans 
RE: B-36 build thread and free plans - 
