vertol

My Feedback: (18)

Hi guys,
For those of you w/ a KMP P38, Wondering how much they weigh in at and w/what eq?

I'm looking to go electric so I need to know what they end up at....

Thanks

vertol

spitmad

Mine is powered by 2 x OS 91 f/s with 2 x 5 cell rx and 3 cell onboard glow in the nose to balance, total flying weight is around 19 lbs.

cheers

Alan

vertol

My Feedback: (18)

wow

evan-RCU

MIne is almost that heavy with twin GMS .75's and extra servos, 2 for elevato, 2 for rudder, 2 for flaps, 2 for aileron, 2 for throttle, 1 retact.

But it flies like it is very light. After all the quality problems she does fly well.

vertol

My Feedback: (18)

Anyone gone electric?

I was planning on going 8s w/ a C5065 motor (like a e-flight 60) but now am thinking of going 4s w/ motors more like a 46 in power....

have you guys seen the artical of the P61 thats electric w/ 4s and 40 size motors?

thanks for the input guys,keep it comming....

anyone know what the ship weighs in at w/out engines/motors?

thanks again

Vertol

evan-RCU

There was an electric, do a search you should find it...

Glacier Girl

My Feedback: (4)

Mookie1 did a conversion on the VQ P38, it's similar. I'm doing one now. Also Mike Pope, and I did the CMP versions, 90". My CMP weighed approx 21 pounds RTF.

jditton

2 x OS46, a little ove 7kg (15 1/2 lb).
It's not what you put in, it's what is left out.................
Electric is very tempting, cost for good performance is still up there though!
Best luch
JD

vertol

My Feedback: (18)

Dj,
how well does it perform w/ the 46s?

how well did it balance out?

what did you "leave out" ?

what landing gear are you using?

thanks

cottp51

how are you hooking up 2 x 5-cell batterys to you Rx? I just ordered one of these planes and was wondering what to do about battery life with all those servo's

jditton

What did I leave out? Well, anything not essential to the flying, ie on board glow, gear doors, pilot(!), bigger engines and so on. Using 46's did save weight, but some nose ballast needs to be used.

Main landing gear is still stock, and yes it's pretty average. Also puts the wheels well aft of the scale location. I fly off grass and find it is hard to rotate on takeoff. I'm looking at the options re shifting and making my own retracts for the mains, have already made a nose gear assy.

Flying is good, enough power but it won't pull 1000ft loops....................and it's not a fun fly. Needs a fair amount of right rudder with power, one of the penalties for not running contra-rotating props like the real ones I guess. That's a definate advantage with electric.

Cheers
JD

vertol

My Feedback: (18)

Hi guys,
Thanks for all the input....ok,now on to a related question...

what landing gear are you all using, and .....do you know anyone who may have ...sad to say....

crashed a 38 w/ good gear that wants to sell them....

thanks as always....

vertol

hidale

Alan. Have you flown the 19 lb. P-38? I have been afraid to fly mine at 17.5 lbs with two 4 cycle 70s. That's 47 oz/sq ft.
Higher wing loading than anything i have flown so far. I have added the engine syncronizer also. That may save the day.
Dale
[email protected]

spitmad

G'day Dale
I actually flew my P38 again yesterday for the first time in over a year !.........it's been hanging in the garage gathering dust since the last flight in Nov '06 .
Once airborne it flies well although it must be yanked of the strip (I think my nose strutt is too short as it used to fly itself off with the original longer strutt......but I replaced it with a 105 deg. robart strutt which I cut a little too short) ..........anyway performance is good with the 2 x 91s..........I'm glad I went with the 91 though as I think it would struggle with 70s (although the 70s are quite a bit lighter).

The 38 is not a nimble aircraft and you will find the roll response almost like a delayed reaction due to the wide set engines, it is fun to fly and lands easily, with full flaps deployed you line her up and just throttle back and flair just before touch down. I have not had any flame outs (thank Christ) but I do have an onboard glow for added security. Loops are nice and big but you must keep the energy up as it does wash off airspeed very quickly, I actually tried a too big a loop yesterday and it stalled inverted and snapped into a lazy spin......luck I was "three crashes high" when I tried that
As you only have 70s for motivation, I would suggest you keep the flights very scale and only attempt high energy manoeuvres (gain lots of airspeed first.)
My 38 has had around 30 flights to date and the only issuee is the nose wheel occassionally fails to lock which results in a nose grind......but I fly off grass so no big deal.
Best of luck ..........you will love the sound of the twin 70s purring away...........and low strafing rauns are great !

Alan

vertol

My Feedback: (18)

Hi Guys,
Well,its been a while and its time for an upadate and a special thanks to all who have offered any tips or thoughts....

So here we go....

Background first. I have been flying R/C since I was 14yrs old,mostly helicopters,then airplanes and now both and electric planes and helis.....can't believe I just turned 40

This is my THIRD KMP p38 ! the first one was my first expierience w/ a 4 stroke engine(s) the local gurus all sugested saito, so I got 2 saito 72's.....I could not gt them to run steady inverted no matter what I did,on board glow,local
expert help.....I ultimatly flew it when it was running at its best, had some good flights, ultimatly lost a critical engine and spun it it (I actually had several flame outs w/ successfull dead stick landings)
the plane also suffered from classic kmp retract problems....

Ok,on to #2.....ok so in talking w/ several people we figure saito may not be the way to go.....so we go w/ YS 63's.....MUCH BETTER w/ there pump system they ran 10X better than the saito's ,had several good flights,a few more flame outs and finally another bad combination of altitude/airspeed and a dead engine......

Ok, maybe I'm not going to be the 4 stroke guy....SO.... lets keep it simple,side mounted OS 61's; 2 stroke,thank you very much!!!

So here I am w/ the 38 in the box,2 new os 61's and I happen to get a Hanger 9 P40 warhawk.....GREAT model (all the hanger 9 war birds actualy)....I start off w/ a ys91 4 stroke (by the way,ys is the ONLY 4 stroke I would ever buy or recomend to anyone)

After flying the p40 which weaghs in at about 9lbs w/the ys91 (the performance was like a 3d plane) I figured the P40 would be a great way to break in the os61's for the P38.....while doing this I saw a vidio of an ELECTRIC kmp P38 and it dawned on me (Ok think it but don's say it ,......DUUUUU) I have NEVER had an engine failute w/any of my electrics ....why not go electric!

Ah,now a whole new set of questions, 4s,6s,8s? motor? speed controler? So now the P40 becoms a test bed for the motor/speed control combo that will end up in the P38.

Then the price hits me. WOW this stuff is not cheap! the good news is that by now I am flying a Hirob Lepton so I have some good 4s packs,so I decide to go 8s in each Nacell,for a motor I actually went w/ a chinese copy of an 8s axi for like $60 a piece and end up w/ a CC- HV45 for a speed controller.....ok, now we start playing around w/ props,flight times and reserve time for the baterys .....w/8s 3700ma packs and a reserve of 15-20% batery I am getting 7 Plus min of flight time....Not too bad

Ok, so this looks good,on to building the latest P.38 and where we are now.

So as I type this,I am looking at the 90% completed Model,I bit the bullet and went w/ the full Robart retract system custom for the KMP P38 (F..n thngs are expensive) going w/ 8s,the chinese motors,and CC 45HV.

One great thng about electric is that I can change the direction of the rotation of the prop by switching two motor leads I am using APC 13 X 8 electric props and and they make a 13x 8 Pusher prop .....

GREAT, ......BUT I picked up two new "tru turn" P40 spinners,really nice,...CRAP,I need one w/ a cut out the oposite way.....got to call them on tuesday after the holiday, and see if they can custom cut me a spinner cone.

so for now back to both turning in the same direction....

I have futaba 14 mz, not sure which rx I am going to use,maybe a 9ch pcm....I also have a spectrun dx7 but the featurs are so weak compared to the 14... But the word is the 2.4 has zero issues w/HV electrics....any thoghts on this one guys?

And now on to weight.....I have been trying to be concious of this the whole time....at the moment,onthe scale it weighs in at 19.2 LBS!!!!!! At least it balances out well (no balast needed)

All std Futaba servos except for a mini in the tail for elevator and a mini for the air valve of the retracts....1700ma batery pack.....

Thats all for now ....will keep you all posted.....

VERTOL

ram3500-RCU

My Feedback: (221)

"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."

Found this on another site. Thought it might help you.

vertol

My Feedback: (18)

Hi guys,
Well it flys!

Its heavy!!!! 19.5LBS

Went w/ ROBART custom retracts ....glad I did,they are worth the $$

I am using 4 4s packs,2 3700ma in serries,tied in parrallel to 2 4000ma in serries essentially making one big pack.

I went counter rotaiting,only had one flight like this.

using 2 CC hv45s w/ 13x8 apc electric props.

perfiormance is "scale warbird like"

I did not get near the performance Ram3500-rcu described....but he was using different props and I am using very inexpensive chinese motors (56$ each)

I do have one Maxx products motor that pulled the P40 around w/ much more authority than the chinese motors,so I may get a second one and swap out motors...

as described in the other posts it flys really well despite the weight

thanks again for all you tips

I'll keep you posted.

VERTOL

spitmad

I use a Multiplex 12 channel RX, this has 2 x seperate battery inputs into the RX. The RX has built in battery management smarts which draws from the battery with most charge. In the evnt of a bettery failure (flat battery or switch failure) it reverts to the one battery supply.
The MPX RX also has a max servo output of 7 amps, the danger with lesser RX's is that the servos (I think I have 12 in the my P38) can draw so much current it starves the RX of juice.
This also negates the need fior power boxes or Smart Fly stuff


I actually had a battery fail in my TF Giant P47.............if not for the dual batts and the Multiplex RX............the model would have gone to god

cheers
Alan

edirhino

Can someone tell me what the engine incidence should be for the KMP P38. I know Twins need some offset but I do not know how much.

jditton

I'm not convinced twins need offset, all the twins I've made/converted have flown fine with the thrust lines at 0/0 degrees, ie 0 downthrust, 0 right/left thrust. Some theories have the propwash angled towards the (centre) fin, but a P38 has 2 fins so I don't subscribe to that one here. Full size aviation twins don't appear to offset the thrust lines, I suspect the engines being so far away from the aircraft centre line means the offset available makes little or no difference.

The KMP P38 could possibly benefit from some right thrust - mine needs significant right rudder at full power, I've mixed rudder with throttle and not adjusted engine thrust lines.

Cheers
JD

vertol

My Feedback: (18)

Hi Guys,
here is a little update...the P-38 is still going strong,over a Dozen flights ! (this is huge to me since I nevr got more than 3-4 out of my previous 2 Kmp 38's)

I ditched the Chinese motors and got Himaxx 390's,the chinese motors were actually really good but they were 350kv and the max motors are 390 and capable of 9s.

I also tried 2 e-flight power 60's on 7s 14x10 they go pritty well but I must say that you DEFFINITLY feel the difference w/ a counter rotating setup vs two turning the same way.

So w/ this in mind,I have been limmited to 13x8 counter set up.....(anyone know of counter rotating 14x10s out there?)I am also trying to stay under 50ish amps as I am using CC hv 45s.

9s and the hi maxx and 13x8 yealds AWSOME performance! shorter run time but a WOW run of 5 min.

My next batch of batteries will be 9s 5000s so we will see how much the extra Ma helps the flight time....w/good throttle management the 9s can have a good flight time since your below half throttle ALOT


Gota run,more later....

vertol