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Old Nov 29, 2012, 12:20 PM
Yes it was Abby Normal
Joined May 2012
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Originally Posted by eggsplurt View Post
I have the luxury of flying at a sod farm here in N.J.....I can get a Piper Cherokee in and out of there......so, with some added fashioned Coke bottle plastic, etc. to the center section and under the nacelles, the underside stays perfect.......I'll get some pics.....Steve
Eggcellent EggsPlurt!!

Please post up when you can.....

I may just build up my HK V1 P-38 for hand launches and belly landings ....will definately use your belly undersides modifications for the added protection...of course I will add carbon fiber slats in the wings and fuselages, stabilizer and rudder...add counter rotating props ....then prepare for spirited sorties and give our turkey buzzards a warning or two when needed

TwistedGrin
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Old Nov 29, 2012, 08:57 PM
Yes it was Abby Normal
Joined May 2012
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Well I started to work on my JPower P-38 this evening and found that I only needed to apply a little more pressure to both of my port and starboard fuselages. I discovered that both sides foward screws could be torked down a lot more....so I compressed both of them and got things a lot tighter. Both fuselages are now much tighter and both booms now hold axial square much better. I may squeez in some hot glue to the front saddles of both boom fuselages just for extra measure only.

Now I just need a flight check to see how much of a difference this provides....I am not expecting much if anything.

TwistedGrin
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Old Nov 30, 2012, 08:33 PM
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Monahans TX
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Well, here's to hoping that it fixes the wiggling

The nacelles/tail booms on the V1 were glued solid on mine and it still wiggled like crazy in turbulent wind.
However, your V2 has some CF to stiffen it up, so you might have the issue nipped in the butt...
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Old Dec 07, 2012, 01:04 AM
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Beaverton, Oregon
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Been enjoying this thread ever since I received my V1 from General Hobby several months ago. I took my time in getting it assembled and ready. After final adjustments, I might get get to maiden it this weekend if the weather forecast holds.

One thing I've not seen mentioned in this thread are specific measurements for control throws. The PDF "manual" doesn't mention anything about it, either.

Can someone who's actually been flying their V1 successfully give me an idea of their actual working control throws for aileron and elevator? I'm mainly interested in scale-like flying, not extreme aerobatics.

Also, can you confirm (or dispute) the manual's specified 70mm CG? Personally, I lean towards a slightly nose-heavy maiden flight.

Also, I spent a lot of time getting the OEM mechanical retracts adjusted so that they'll actually lock into the down position. They're quite rickety, though, and I'm not optimistic that they'll last very long. I've got a set of servoless units on order. I wouldn't mind trying the OEM units out for a few days, though. Any hints/suggestions, aside from replacing them entirely?

Thanks,
-- Rod
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Old Dec 07, 2012, 05:11 AM
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Sydney, Australia
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I think I can answer your questions.

I set the throws to as much as I could get. The model is still docile, and I wished I could have more. That said though, I don't fly my p38 much, because I prefer 3d models. I also set the cg to 70 mm and found that I had to move it back from there to get the elevator response I wanted. I'd say 70mm is a good starting point for scale flying.

I also spent quite some time setting up the stock retracts. A nice firm down lock I found was key. Yes the servos buzz when down, but they work. I've been very gentle with mine though, so I couldn't say how long they would last.

Hope this helps.
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Old Dec 07, 2012, 09:23 AM
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China, Shanghai
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I also set my throws to max without servos buzzing, and then set low rates to I believe 70% on ail and 80% on rudder and elev. I have only flown with low rates since I fly scale and they are enough for me. Can still fly loops, rolls and all I want.

I use a 3S 2200 30 C Lipo (don't ask me how much it weighs) and it did balance at about the said 70mm. the Lipo fits in tight but fits. Just make sure you secure the hatch well otherwise it will fly off and you'll lose it. Flys nice and balanced there.

My U/C is weak like everyone's. I fly off a paved runway and they held out maybe 10 flights. Then one started to sporadically hang and I had to cycle a few times in the air to get it up. It was getting worse. They were also sometimes leaning in because thay had a lot of slop. Finally I bought some servoless retracts and bigger wheels before the original ones gave out. To increase their life times, you definitely should program a mix to shut off the nose gear steering when retracted. Search this thread for the set up. Others have put some washers in to reduce the slop. Unscrew the mounting plate, pull the retracts out, push out the pivot pin and put in the washers as needed.
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Old Dec 07, 2012, 10:03 AM
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Originally Posted by rrobbins View Post
Also, can you confirm (or dispute) the manual's specified 70mm CG? Personally, I lean towards a slightly nose-heavy maiden flight.
Rod:

I'm at the same point with my version 1 that you are with your plane. I'm anxious to hear how your bird flies, and what CG position and control throws you use. I was wondering about the control surface deflections, too, along with the CG position. I ran some CG calculations and came to the conclusion that the recommended CG was pretty far forward. Normally, you would want a static margin of around 15% (for reference, 3D planes want to be neutrally stable, which is to have a SM at 0%). Measuring the geometry of the actual model, and running the numbers, it looks like you would have a SM of around 38% if the plane balanced where the manual recommends. Real airplanes are usually designed to have a Static Margin range from from 25% to 5%. The recommended CG in the manual probably guarantees a super-stable airplane, but will probably make the elevators less effective, and if you're in to knife-edges, make it impossible to keep the nose up when you're on edge. It will likely make loops difficult to pull off as well.

As it sits now, my P-38 balances at the front edge of the carbon fiber rod, which is slightly forward of even the recommended CG. That's with my NanoTech 2200 3 cell, and E-flite retracts. I may put some ballast on the tail, but I'm debating what to do for first flight.

I have all the pushrods on the next-to-the-furthest-out hole on all the servo horns and control horns. Visually, it looks like a lot of throw.

I hope you can take the time and give a full flight report, including your control throws, CG position, weight, dual rate settings, and flight characteristics. This plane was took such a long time and so much effort to get finished, that I'd like to go into the maiden which some clue as to what to expect. I'm happy with the final product at this point, but not sure I'm up to doing another build like it, if worse comes to worst!
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Old Dec 08, 2012, 08:24 AM
Yes it was Abby Normal
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Flew my P-38 V2 last evening....I am very suprised at how much difference the plane flies after I really clamped down both fuselage/booms to the wing. The plane is much more responsive...much tighter in the air. Really flies nice

TwistedGrin
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Old Dec 08, 2012, 09:36 AM
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USA, TX, Copperas Cove
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Quote:
Originally Posted by TwistedGrin View Post
Flew my P-38 V2 last evening....I am very suprised at how much difference the plane flies after I really clamped down both fuselage/booms to the wing. The plane is much more responsive...much tighter in the air. Really flies nice

TwistedGrin
That's awesome
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Old Dec 08, 2012, 11:40 PM
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Beaverton, Oregon
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Quote:
Originally Posted by subsonic View Post
I think I can answer your questions.

I set the throws to as much as I could get. The model is still docile, and I wished I could have more. That said though, I don't fly my p38 much, because I prefer 3d models. I also set the cg to 70 mm and found that I had to move it back from there to get the elevator response I wanted. I'd say 70mm is a good starting point for scale flying.

I also spent quite some time setting up the stock retracts. A nice firm down lock I found was key. Yes the servos buzz when down, but they work. I've been very gentle with mine though, so I couldn't say how long they would last.

Hope this helps.
Thanks, guys, for all of your replies.

Specifically,...

Subsonic-- I've got mine balanced at exactly 70mm with a SkyLipo 3S2200 pack. I'm not much of an aerobatic or 3D flier. A nice stable scale-like plane is my preference. I guess I'll leave it there for the maiden, and change it afterwards once I see how it handles.

I'll also leave the throws at max, per your experience. I've got my low rates set for 60% so I can always tame it down in a hurry if needed. I always set up substantial expo, too -- like 50% on aileron and elevator, and about 80% on rudder to tame the ground steering. I set up steep expo so that it acts sort of like dual rates "on demand", without having to fumble with the switches if the handling is too twitchy on the first flight.

gadorey-- Thanks for the tips. I've already programmed a separate channel for the nose gear rudder servo to disable it when the gear is retracted. I noticed the binding with the OEM arrangement as I was setting it up. That OEM setup was pretty lame.

I might go ahead with adding the washers to the gear to reduce the slop, although if the gear looks like it's not going to hold up long, I'll just go ahead with the servoless replacements. I've ordered new units with metal trunions so they should be pretty tight.

DriverRX8-- Yes, I'll check back in with a flight report on the maiden. I received the kit several months ago and every time I show up at the field, the other guys cluster around my van, hoping to see the P-38. I keep telling them that I'm just an old retired guy and I keep getting lazier by the week, and just haven't gotten a "round tuit". Tomorrow or Monday might be the day if the weather forecast holds.

I've got all of my pushrods locked into the outermost holes so that should tame things down a bit. I can always move them inward if needed for more throw.

From all the flight reports I've read on this thread, I'm pretty optimistic that I'm going to like it. My other planes are all Dynam: the C-47, T-28, Grand Cruiser, and Turbojet. I also have the Dynam PBY Catalina in the box, waiting to be assembled. The P-38 should blend right in.

Regards,
-- Rod
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Old Dec 09, 2012, 11:51 AM
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Couldn't Wait...I Went Ahead And Maidened!

Well, I couldn't wait, and I maidened mine yesterday. I have extensive notes and pictures in my blog post, so just click on my name or avatar to the left, and it will take you there. Or, click on the link:

http://www.rcgroups.com/forums/showthread.php?t=1785976

I felt like there was too much text and too many photos to bog down this thread. I'll copy some of it to this thread when I get the chance.
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Last edited by DriverRX8; Dec 09, 2012 at 06:42 PM. Reason: Added link
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Old Dec 10, 2012, 10:29 AM
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South Florida
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Quote:
Originally Posted by DriverRX8 View Post
Well, I couldn't wait, and I maidened mine yesterday. I have extensive notes and pictures in my blog post, so just click on my name or avatar to the left, and it will take you there. Or, click on the link:

http://www.rcgroups.com/forums/showthread.php?t=1785976

I felt like there was too much text and too many photos to bog down this thread. I'll copy some of it to this thread when I get the chance.
Folks, if you have one of these planes, then you really should take a peek at his blog and photos. Very professionally and completely done. Shame it could not come from the factory set up with all those sweet upgrades/improvements, but then it would be high dollars, I know.
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Old Dec 10, 2012, 03:11 PM
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Monahans TX
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RX8, just read your build log...great job!
One thing I can caution you about, you mentioned possibly cutting the crossmember out to fit a larger battery.
I did the same with mine and managed to fit a 3300mah in there with some trimming around the sides.
Problem was that I thought I left just enough to hold it in place, but the battery slid all the way to the back of the gondola during a vertical climb.
If you do this mod, velcro is required, or possibly a rod you can insert to stop the battery from sliding rearward.
It flies fine with the 3300mah, more scale and stable actually.
I'd recommend giving it a try in the future.
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Old Dec 10, 2012, 08:17 PM
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Originally Posted by tracknoob View Post
Folks, if you have one of these planes, then you really should take a peek at his blog and photos. Very professionally and completely done. Shame it could not come from the factory set up with all those sweet upgrades/improvements, but then it would be high dollars, I know.
Thanks for the feedback! It's amazing what I can get done while procrastinating and avoiding home chores!
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Old Dec 10, 2012, 09:00 PM
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Originally Posted by WestTexasKing View Post
RX8, just read your build log...great job!
One thing I can caution you about, you mentioned possibly cutting the crossmember out to fit a larger battery.
I did the same with mine and managed to fit a 3300mah in there with some trimming around the sides.
Problem was that I thought I left just enough to hold it in place, but the battery slid all the way to the back of the gondola during a vertical climb.
If you do this mod, velcro is required, or possibly a rod you can insert to stop the battery from sliding rearward.
It flies fine with the 3300mah, more scale and stable actually.
I'd recommend giving it a try in the future.
Great feedback. Thanks! I'll add that note to my blog post. I am shopping for larger batteries now, and a 3300 sounds about right.
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