View Full Version : KMP P-38 Flies with Axi power
03-28-2006, 02:16 PM
Hello, thought I would let you know how it went.
I ended up with 2 AXI 4130/16 Motors with 8,3 cell 3000 lipo packs - 4 pairs, each pair in series and then the pairs in parallel giving me a total of 12amp capacity (what configuration would that be called), giving a min of 22.2 volts two both Axi motors, amp draw at full power combined draw on the bench was 78 amps on fresh packs - RPM was up over 7000 running 15x10 APC electric props (two blade)
At 19.7lbs the plane jumped off the runway at about 200ft and the climb was incredible. I could easily cruise at 1/2 throttle or even a 1/3. Fast flyer with this setup, did a nice big loops from level flight, some rolls etc. I had the first flight at 9 min and found later that I had only used 1/3 of the battery capacity. Will play some more to find the proper run time - If I cruise at 1/2 I figure I am drawing a combined 30 amps or less as I saw on the bench run. The batteries got luke-warm only.
I had a hard but well controlled carrier landing as I elected not to use my flaps and slowed down just a little too much when she started to drop and the Chinese metal struts bent back a bunch so I need to upgrade my struts as was expected.
I will play with this setup some more and see how she runs for a while.
See photo Attached. Thanks for your help.
03-28-2006, 02:40 PM
Nice job! Sweet field, where are you?
03-28-2006, 02:55 PM
Sedona Arizona, we have a 700 ft compacted dirt/clay runway, a really nice field. We are 90 min north of Phoenix AZ at about 3800 ft elevation. Thankd for the feedback.
03-28-2006, 03:20 PM
I would die for a site like that. Guess I need to transfer.
03-28-2006, 08:58 PM
Nice ! ;)
03-28-2006, 09:55 PM
Nice articile on the P-38 using the AXI 4130/16 motors. The batteries would cost about $700.00 to run that airplane. I like the P-38 and have the plans and templates to build one. I was going to use the Ryboi gas motors but are making me think different. I just do not like th price of the batteries. What type of batteries are you using? I would like to know more about your airplane. I hope you can find my e-mail. I do not like to give it out on this. Any way good job and I would like to see some video on it. Walter.
03-28-2006, 10:46 PM
Walter - The batteries are from Dymond Modelsports out of CA. The packs are 3000mah with a 12C rating and cost $65.00 each for a total of $520. "+ tax, tag, and shipping" The quality of the batteries are very good, no they don't have taps in them, but they are only 3 cells and if you treat them well, the price tag can't be beat. Several guys at the club use the Dyamond packs to great success. The nice thing is that YES the batteries are expensive but I don't have engine outs, I can get 20 min + of flying out of the set, and when I don't put them in my P-38, I put 4 into my H9 Mustang for 20 of flying, and 4 into my Great Planes Stuka for 20min, or 2 in my Long EZ, or one in my Combat Corsair, or one in my Siren Glider, or two in my Bronco . . . - All my planes use the same batteries, so all in all the battery cost is spread out to my other planes. The initial investment is High, but so is getting into good glow or gas engines. Flexiblity is key, if I were to buy all this "Stuff" for one plane forget it. Hobby Lobby is running a great axi motor sale now, so if you are going to do it, you can save a bunch going with Axi.
03-29-2006, 06:00 AM
Congrats on a great conversion, really nice plane. I have to agree with mmm, that's a great airport you guys have there.
09-06-2006, 12:45 AM
I have a new source of 4000mah lipo batteries - these are proving to be true 12C batteries. I am running them in my Hanger 9 P-51, my 65" spit and my P-38 all running AXI 4130 - 16 with 15x10 APC E-props. After 9 min of flying my p-51 at 3/4 and above they get slightly warm and no more. Running 6cells. $60. per battery, they have balancing taps too. Great Batteries, very pleased and a fraction of the cost.
09-15-2006, 12:47 AM
It looks like the pic was taken at the general aviation field. C'mon now, tell the truth about Sedona. It is beautiful, but very tourist oriented and there is no industry. I'm willing to bet that you work in the home building arena.
Anyhow, enough of the joking, looks like your P38 came out nice and is also a nice flyer. I'm encouraged that the Axis flew that baby on 1/2 throttle. Looking forward to seeing a video.
Oh yea, where's the link for the great lipo batteries? Play nice, we have to share our good sources.
09-15-2006, 01:11 AM
Thanks for the comments - actually I am a Creative Director with a Publishing company. Your right Jobs can be tricky. I actually live 15 south of Sedona in Cottonwood. Tourist area is small, uptown Sedona they call it, the rest is beautiful and wild.
I had another flight last weekend, cut my battery load down once again - 2 3cell 4000 lipo packs per Axi 4130-16 Was an awsome flight and plenty of power at my 3800 ft altitude. It dropped a pound and is now 18 pounds.
Share the source . . . I don't know . . . maybe. I am telling you the packs are just outstanding for the price and real world use. OK: firstname.lastname@example.org, his name is Richard.
The guy stands behind his batteries, I have yet to have an issue. I am continued to be amazed at the real world results I get. 2 are a perfect match for my axi 4130-16s running a 15x10-16x10. 8-9 min leaves 1000 mah capacity in the pack - a good safety margin.
09-15-2006, 01:24 AM
Looks good. Are you going to bring it to the 2007 Arizona Electric Festiva (Jan. 25 thru the 28)?
09-15-2006, 03:48 PM
I could kick myself for not going last year! Get me the dates and I will be there.
12-27-2006, 02:31 AM
CHRIS, please let me know what supplier u used for the new landing gear legs...I am having the same problem, thanks
01-01-2007, 09:13 PM
KMP offers a Robart system, which is going to be non-spring-out and heavier.
You couls always ask them for the specific type they are or order from them direct.
I am building a setup close to his.
Two Axi 4330-16s and 12000mAh. But I am using two 8000 and two 4000 packs. Plus I am running 3 blades instead of 2. Right now 50 Amps per motor and I hope to stay closer to 17, 18 pounds. It should be done by this weekend with a possible maiden on sunday.
I'll keep everyone posted. And yep, I wonder how that landing gear will perform. Supposedly I got the 3rd generation here from KMP...guess they were aware of the problems...the ones I have look and feel real study.
01-01-2007, 09:31 PM
Found some killer retracts....at a "killer" price...unfortunately...
What's even worse.....I was making some progress today and got to the point where you install the retracts....turns out the ones that come stock were real bad. Struts wouldn't even fit into the retracts without some grinding and the valve was clogged!!! Then I measured the pressure needed to work the retracts and it was at 4 Bars (sorry..can't get the German out of the German...I am clueless when it comes to Fahrenheit and Psi), whereas I work my other air'tracts in my DH88 Comet at 2 Bars.....and I didnt feel too comfortable about the whole thing anymore. Then I read about the KMP ones supposedly to trac inferiorily...
After giving it some thought I talked myself into ordering the Century Jet retracts. I compared them online to the Robarts and in my opinion there is more craftsmanship and better looks to be found with the Centurys. Now I hope that their airsystem is worth the ticket price and that they will not turn out to be too heavy.
01-02-2007, 05:39 AM
We got our stock retracts installed without too much trouble and they charge up fine and work as expected. My son has returned to OU so now I'm both shop assistant and foreman (scarey!). I've got to finish dialing in the servos, programming the esc's (Jeti-77's) and testing the whole monster. God its BIG! DerGoetz, you and I have the same setup, same Axi motors but I think I'm going with 2 blade props for more efficiency and power (I've never found 3 bladers to work as well as two bladers). My maiden won't be for months I'm sure the weather here in DC is typical January cold rain (like Hanover or Weisbaden).
01-02-2007, 06:19 AM
It's absolutely fantastic that we keep running into each other on the forums, sharing our hobby.
Yea, I know about the decrease in efficiency, but heck, I am throwing 2400 Watts at an 18pound bird. And the sheer looks of the three blades just won me over. I do have an extra set of two-blade spinners and I think I will compare the 13.5*13.5 three-blade against a 14*12 two-blade setup in the future...but right now I am just getting a kick out of that three-blade look.
Right now I am doing some airbrush work on my Yippee, I have a foto here of the original plane, and you will NOT believe the exhaust staining on that plane. Its ridiculous...I already know that once people see my plane they will think that I screwed up, hahaha....next up will be painting the spinners red, and some more detailing. And I ordered right size decals and the stencil numbers for the rudders....the Century retracts will hopefully round everything off. Man, I am so excited, this will be my most scale bird so far. Last one I finished, other than my DH88, was the Hanger 9 1.50 size P47 and it came in at 23 pounds on 850sqinches wing area!! So....the 18, 19 pounds on my lightning do not impress me one bit, hahaha....the P47 is still missing some decals...working on it....
One thing I would like to know...where are you putting your batteries??? I will tape everything up tomorrow so I can figure out what I am looking at....hope they can go right in the nose of the center pod. Since the screws on that nose cone would make access very easy.
01-02-2007, 03:38 PM
MattP-51 - I made my own out of piano wire I got from Ace Hardware, will have to measure the diameter, it has been a while. I still plan to replace the nose gear with Century spring down - the stock nose gear, even with a stronger strut just is not up to the task.
01-02-2007, 04:25 PM
Topher, where did you place all your packs to get to the CG?
01-03-2007, 08:10 AM
Our 2 lipo packs will go in the nose for access and balance. We're using two ThunderPower 5s 5000 mAh Extremes and two Jeti77 esc's. I don't have the exact balance point worked out but they've got to go waaay forward.
02-19-2016, 01:37 AM
Hi topher39 I know this thread is from along time ago but did you happen to sale this p38 to Scalefan from corona CA? If so I have it now and it is still around and flying.
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