Tiger2 Electric Conversion

I have had an old Carl Goldberg Tiger2 40 that I had a .61 ASP in that I built over 15 years ago and crashed. The right rear horizontal stab was broken. Anyway, it has been gathering dust in my garage for years, and I was thinking I would try to repair it and outfit it with a new electric motor. Just came across this thread in RCGroups, too, that seems to discuss it.

So, I pulled the old motor and gas tank out, as well as the old throttle control and the old airtronic servos. I did some quick measurements of what this thing weighs without the old nitro motor and stuff, and use the 100w/lb basic rule for motor sizing (actually, move that to more like 130-150w/lb for aerobatic performer), and came up with the following:

Base Plane	1550g
Motor + Mount	300g
60A BESC	75g
Servos + Rx	75g
3000mAh 4S1P LiPo	320g
Total	~2320g (~82oz or 5.2 lbs)

Update 5/11:
I got my Hobby Wing 60A Pentium ESC (same as Turnigy 60A Plush) in, as well as the Turnigy AerodriveXP 35-48 900kv motor and my 3000mAh 4S and 5S batteries (as well as a lighter 2200mAh 4S). I also got some light metal gear servos. I decided to open up the front firewall, and move it forward about 2.3" to help with the CG, which I'm sure is going to need to be moved forward (calls for 3.5" to 4.3" from LE of wing). I'll play with the placement of the 5S and 4S lipos to finish balance it, but moving the firewall forward should help a lot of options. I'm going to rip out the old servos and tray and I think I'm going to try to put the elevator and rudder servos in the very far back sidewalls of the fuselage. Moving the motor/firewall forward should afford me this latitude on that much weight clear in the back and it will cut down on some needless linkage. Not sure how I'll refit the smaller servos in the aeleron, but maybe an HS81 will work better in there. Here are some pictures of the cut out firewall and the new one moved forward.



Update 5/13:
I ran some watt meter tests on the new motor with the 60A Hobby Wing ESC and a 12x8 APC prop. 4S and 5S. Unfortunately, I turned off my transmitter while taking photos of the readings, which is normally fine, since the Rx just goes into safe mode and locks out...but all of the sudden, it must have gotten a signal of some sort and it glitched (scared me) and I smelled nasty burnt electrical. It didn't run very long (a second at most and very intermittant, so not full thrust even close), but when it got done, the peak current read 160A...Uh-oh...must have been fast enough different signals to really fast mess up the timing. Powered the Tx back on, and ran it to cool the motor, and at first it was sort of stuttery, but I ran it at half throttle (19A) for a little bit, and then full, and it seems ok...I hope...
4S1P 12x8 APC - 47.91A, 722W peak
5S1P 12x8 APC - 62.57, 1120W peak (ouch!!!)


Update 5/30:
I got the elevator and rudder servos in the back fuse below the horizontal stab, and also replaced the larger old airtronics servo in the wing for the aileron with an HS-81. Balance point is pretty close to the 4" mark back from leading edge with the 5S 3000mAh Lipo in place, and AUW is 4.75 lbs. Not bad, actually. The aileron throws seem limited and the HS-81 is making some grinding sounds (doh...hope it hasn't striped a gear). Everything seems pretty well done at this point. Just need to figure out how to best anchor down the ESC and Battery (hook and loop velcro isn't sticking to the wood...I may have to put some CA glue on the surface for it to have good adhesion). Nervous about flying it now.




From this, I figure I can try to plop a 500-675w motor (figure LiPo delivers 3.3v/cell under load, and I need something in the 45-50A range. I'll need to work out how the CG moves (it needs to be 3.5-4.3" back from wing LE) with the move to an electric motor and LiPo and stuff. I've had this in a tail dragger config since I built it, so that will be interesting.