All,

Finally finished my new Excitation profile with AXI 2820-8, A123 3s2p battery, CC 45, Ztron III timer. Ship is 54" span, 595 sq in, 57oz, 64ft 0.015 lines. Motor run after new CC 2.0 firmware download was 8600 (was 8800 with 1.5 version). First several trim flights had 5.3 lap with an APC-E 11.5x5 @ 8600rpm. Increased prop pitch to 5 3/4 and lap time came in at 5.0. Have to do a small flap tweak to level the wings, inside flap is a tad low causing roll out upright and in inverted. May increase lines to 66' since the ship is solid on the 64'.

The new firmware works fine, the brake was set for high. It slows prop but does not completely stop unit model is almost on the ground. Pic's below.

Best,        Dennis

Dennis:
VERY nice squeeky clean set-up - way to go! 

Keep us posted on flight trim progress and REAL WORLD expereince with the A123's.

Dennis,
Just a question--why don't you adjust the throttle to get your lap time instead of tweaking the prop? I find it works quite well.

With the new rpm mode on the CC ESC, you seem to be able to hit any rpm you want--only downside is that you need a laptop at the field if you want to change the rpm right then. In high governor mode, with the CC ESC, the rpm "clicks" were a couple hundred rpm/click on my JMP-2 timer and a 14 magnet motor (as I recall).

Dennis,

Nice looking ship and setup!!

Looks like you have firmly affixed the A123 to your plane. Does this mean you are recharging the battery while it is on board? That would be a no no for Li-Polys but is probably OK for A123s. How long is the recharge time after a flight? I have six Li-Polys so that I can swap them out and get fairly frequent flights but with rapid charging for A123s you might only need a few (that would save some $$).

John

Dennis,

I'm running the Nobler right now in rpm mode and it seems to work great. However I do confess that I didn't actually measure the rpm, so it might be slightly different than when running in High Governor (HG) mode. Anyway this is what I did.
1) I put in the battery and motor kV&magnets info into the panel when asked.
2) For throttle less than 50%, I asked the rpm to be 7000 rpm (this is from memory, it might be a little higher).
3) For throttle greater than 50% I input a target rpm of 8050 rpm (50 less than the average I was flying with in HG mode).

Then I set up my timer so that the first flight time was 20 seconds at a throttle setting just a little less than 50% (~30 out of 63 on the JMP2 timer).  Then I set the final throttle at the end of the flight to be ~98%.

Here's what happens.
1) I push the start button and walk out to handle.
2) 20 s later the motor spools up (I have medium spool speed) to ~7000 rpm. I take off and fly 3 laps total at 7000 rpm.
3) Somewhere an the 4th lap, the automatically increasing timer throttle output crosses the 50% threshold, and the rpm increases to 8050 rpm. Definitely feel that. Plane flies at this setting for remainder of flight (total flying time is 310 s--doesn't include the delay time).

Idea is to try and have a nice smooth takeoff--we will see how that really works.

I probably will increase the 7000 rpm to ~7500 rpm to handle windier days. Also I will slow down the throttle response so when the rpm "jumps" to 8050, it will be a smoother transition. It is a big jump right now. I think I am currently set for medium throttle response.

Also I don't really feel the two warning blips at the end. Or I should say that I do, but the motor seems to quit almost at the same time. My brake seems to work quite nicely--I have a "hard brake" but with a medium ramp (and 0.3s delay --the minimum I think).

What I also like is that the ESC beeps every 10 seconds or so to remind me I still have the battery connected. Also my motor seems to have a smoother start now than it did in the past with the older CC firmware.

I also added an arming plug this year---I had one last year, but when I went to the 4s2100mAHr battery, the space inside the tank area got more crowded and I left it off. Finally put in some effort to come up with a reasonably trim setup that still leaves a lot of room to put in and take out the battery pack. I'll take a couple of photo's tonight to show how I did it.

Hey Dennis your set up looks really good, how about a close up with everything conected. I would like to see how you mount the motor. OK here's the newbee question, what are A123 batteries ?? Thanks

All,

Have completed several trim flights and now have the wings level and am working on prop tests and amp draw down. I started out with the same setup I used in the test ship and with the exception of needing to adjust the pitch up to correct for the 200 rpm slower prop rpm when I installed the new CC firmware (it was easier to change the pitch then mess with the dip switches on the timer) all worked as planned. I started with the APC_E 12x6 cut down / repitched to 11.5 x 5.75. This pulled 54amps static @ 8600rpm which was the same amps as on the test ship. Lap time was 5.0 on 64.5' lines battery draw down was a little higher then the test ship when I did the full pattern at 4140mah out of the A123 3s2p, 4600mah pack. Problem was after I finished the pattern and got the three blip warning it went two laps and must have been 3 sec or so away from the normal shut down and brake when it hit the low voltage cutoff and just slowed down without cutting. Looking back to some information that Igor posted were he indicated that the cells could be below 2.8V or 8.4V for the pack, I reset the low voltage cut out to 6.3v. Others have indicated that the A123's can be drawn down to 2V or 6V for the pack with no reduction in life. At 6.3V voltages I will still be at about 91% throttle with the AXI 2820/8 1500K rated motor and should have lots of room to complete the 5min 50sec flight time.

I tried an APC_E 11 x 5.5 repitched to 6 and got to about a 5.4 lap time and was able to do the pattern and get to a normal shut down with a draw down of 3184mah, this was close and showed that I had plenty of battery left to increase the pitch to get the lap time to 5.1 that I want. I did a static amp test and this prop only pulled 34.5 amps. When the prop was pitched up to 6.5 the draw was 37.4 amps still lots of room. During the two tests the difference in thrust is very noticeably just holding the plane. I think the APC_E 12x6 has more under camber in the middle of the blade then the 11 x 5.5 and even when cut to 11.25 diameter still pulls 53 amps with very little reduction in thrust. I hope to do some additional static tests on a RevUp 11.5 x 7 and a Top Flt Power Tip 12x6 (the TF 12x6 I did fly on the test ship and it was almost as good as the APC_E 11.5x5.75). Hope to do some test flights  tomorrow.

Best,         Dennis

Great, Dennis!
How is the grunt in the clover?
The 7" pitch does not surprise me at all: with the A123s in a 3S combo and a 1200 Kv motor running close to 40Amps, you really end up with maybe 7-1/2 volts after the copper loss. With a 1200 Kv, you really need to run at or below 9,000 and that means a little more than 6" pitch to barely get the lap time you want, with the available voltage. 6" was almost enough pitch, and that probably led to some interesting but wasted experiments.

take care,
Dean Pappas