So, I read your message thinking "I have nothing to add, I don't fly combat".  But...

The ESC current limitation isn't going to affect performance, it's only going to affect when ESCs burn up.  And different ESC brands with the same ratings will act differently at any rate, because some manufacturers do something with the truth that marketing people call "making it look more attractive" and which ordinary people call "lying".  Going to a higher rated ESC may gain you some tiny advantage in lower resistance, but it's going to take that away with more weight.

The airplane performance is really going to be affected by the prop used, the number of battery cells, the voltage constant of the motor (so-called Kv, although this term is only used by the model industry), and the total resistance in the system.

I'm trying to think of the best way to set your rules to put everyone on a level playing field, and the best way I can think of is to either call out a specific part number of motor (and hope the manufacturer doesn't change it), or to allow anything that turns below some specified RPM with the regulation prop, with a fresh battery.

What do the 'lectric RC racers use?

Looks like I need to redo my motor calculations. The motor I had originally thought would work is to slow for 45' lines. Even marginal on 35'
Next step is to talk to Bill at Stevens Aero about it. Maybe he will have a recommendation as I saw a picture on his website of one with a larger silver outrunner motor

For that size bird WEIGHT is critical.  Suggest standardizing on the APC 6x5.5E prop, 3S x 500 pack and a 3 minute(?) time limit to keep battery size down.  There is not a lot of cost or weight save going from 10A to say 18A ESC, I think the larger one woud be more cost effective by virtue of robustness.  2205 motor should do the deed, for 3S anything over about 1300 kv should work.

Have you considered Spiderwire lines?

Thanks the 2205 will work nice. (see ecalc below)  Should put us real life around 58 or so mph.
Have considered Spider wire but know there are some in my club who don't have a high opinion of it being used at our field.
I'm waiting for Bill from Stevens Aero to contact me to verify the fitment of a larger lipo. Not sure a 450 or 500 will fit.

Ecalc results

Battery
Load:   19.23   C
Voltage:   10.46   V
Rated Voltage:   11.10   V
Flight Time:   3.1   min
Mixed Flight Time:   5.3   min
Weight:   39   g
    1.4   oz
-----------------------------------
    Motor @ Optimum Efficiency
Current:   5.18   A
Voltage:   10.66   V
Revolutions*:   14660   rpm
electric Power:   55.3   W
mech. Power:   45.9   W
Efficiency:   83.0   %
    Motor @ Maximum
Current:   8.66   A
Voltage:   10.37   V
Revolutions*:   12694   rpm
electric Power:   89.8   W
mech. Power:   72.4   W
Efficiency:   80.7   %
est. Temperature:   39   °C
    102   °F
-------------------------------
    Propeller
Static Thrust:   585   g
    20.6   oz
Revolutions*:   12694   rpm
Stall Thrust:   263   g
    9.3   oz
Pitch Speed:   106   km/h
    66   mph
Tip Speed:   365   km/h
    227   mph
specific Thrust:   2.93   g/W
    0.1   oz/W
--------------------------
    Total Drive
Drive Weight:   109   g
    3.8   oz
All-up Weight:   113   g
    4   oz
Power-Weight:   850   W/kg
    386   W/lb
Thrust-Weight:   2.33   : 1
P(in) @ max:   96.1   W
P(out) @ max:   72.4   W
Efficiency @ max:   75.4   %
Motor Characteristics

For something that was supposed to be simple, sure got complicated.   If you have a combination that works,  why not make it the same for everybody.   That was done with Shoestring Racing in the early days.   One airplane design,  one engine for power and entrant had to fly his own plane.   Even the rules stated had to be built as close  to kit as possible with 1 ounce fuel tank.

For something that was supposed to be simple, sure got complicated.   If you have a combination that works,  why not make it the same for everybody.   That was done with Shoestring Racing in the early days.   One airplane design,  one engine for power and entrant had to fly his own plane.   Even the rules stated had to be built as close  to kit as possible with 1 ounce fuel tank.

Yup keeping it simple, one design, approved spec kv motors (many motors are the same but re-branded), one size battery.

1000kv motor
2200 4cell battery
9 x 8/34 wood racing prop

Runs 4 minutes @ 75mph and has 16% battery life after 4 min flight.

Won the Tucson 75mph two years in a row with this airplane against fuel models. No starting time. Stealth sound. Havent hit the ground or another airplane yet to see what happens. Only down side is the prop free wheels until you land. Cracked two props. But did hot stuff it back and used it again. Wouldnt dare try that on fuel!!

Are you using a timer?   I like the looks of the set up.   

O, and that was on 60' lines

Who's wing cores are those ?

A couple years ago I electrified a Li'l Hacker(not a super light design!)  Several people had sent pictures of what they'd done, so I tried it.  For a Half A sized plane on 35 ft lines I soon found that you need about 180watts- 3 cell battery, 16 amps.  That will run off a 1000 mah battery for 3 min.  Turnigy Aerodrive C2826 1650 Kv motor(that exact motor is probably not available any more)Castle 25 amp speed controller, a 2.8gHz receiver, APC 7/5 E prop.  It flys nicely, can do eights, loops, and is peppy enough for some serious combat training.  The performance is similar to the same plane on a  Cox Black Widow engine, but it runs a minute longer.  With the smaller plane you can use a rubber band prop mount and save props.

Bob's simple approach works great too(especially if you already have planes), just a few dollars more.  Since it was built for a 36 combat motor is it a lot more heavily built than needed for electric.  I'm pretty sure with some construction changes it could easily fly just as good on the 22-2300 battery for over 4 min. and still be fairly crash worthy.

The pic is of Andrew Land built with a similar conversion.  I like to mount the motor behind the firewall to protect the can/rotor in a crash.

Here comes some more pics

Try again

OK...I guess just one pic per post. That last one was the bottom of the plane showing the battery box. This is from the front. I just gorilla glued some ply to the top and bottom spars.

Here's the timer. I don't think they're built anymore. What a shame too. They were cheap and simple

Here's the Streak motor. I fly it with the same batteries. I haven't actually clocked it but I think it also runs about 75mph.

This is the modified Streak. I cut the planking and 1/2 the leading edge for the battery. I slipped the speed control in the wing behind the battery slot. Timer on fuse by pushrod exit. Spaced a piece of plywood at the right height to hold the battery snug and run Velcro around it to hold it in. BTW. Epoxy the top battery plywood and use a couple of dowels through. More stress there than you think. I just CA'd it the first time. Shot the battery across the park when I was doing tight outsides. I also build the first motor mount out of plywood glued to the fuse and a couple of plywood supports on each side. That got me over 30 stitches on my thumb. And I was BEHIND the airplane. Now I use an aluminum motor mount. I flew this setup last summer on some rough ground and the plane flipped over on its nose as it was taking off. That smoked the motor and the speed control. It was an older speed control out of an RC Stryker. I hope the newer one will shut down if that happens again. This would be the setup for elect. combat in my opinion. First off its an RTF that everyone seems to want now days. And its not expensive. It flys fantastic. Its easy to modify. And the system is cheap through Hobby King. Brodak has a ready to go system for their Elect clown including the battery and charger for $179.00 I think. I'm not sure that that's not the best idea. I haven't had any problem with my Brodak system and I have had some steep learning curves trying to make a cheaper system work. But I did finally make it work.

Great pics of how it is done by you.   But, you might try shrinking the pics to 100KB or less.   Just time consuming and it is not that hard to do.  Thanks for the pics tho.

Bob M
LOTS of great ideas there thanks for posting! 

The Arrowind 2815 has kv = 920.  For 75 mph target on 4 cells that is not a bad combo.

The Hubin FM-0c timer (like in your pix) lets you adjust RPM & duration but not start delay.  One very nice feature is that it adds throttle over the course of the flight, to compensate for battery voltage fall-off, so the speed is more or less constant.  You could use this timer with a low cost ESC.  Wil Hubin makes other timers that also allow you to change the start-up delay, so you could use the same timer with no delay - in competition or when with flying with a friend, or up to a 30 second delay for when you are flying with a stooge.

Looks like you are using a Phoenix ESC, you should be able to activate the prop brake.  Unfortunately that is no guarantee the prop will stop in the correct position!  Sad to say, a landing skid may be in order...

ECS's all program a littler different, and not all ESC's have brakes.  But you can go online and look up your model number to see if it has a brake and if it does, how to program it.