HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Dec 05, 2011, 01:31 PM
whiirrrrrr
srt8madness's Avatar
United States, TX, Houston
Joined Nov 2011
785 Posts
Build Log
Funbuild 5 - Mountian/Molt Models P-38

Well, as mentioned, I gave up on flying my first P-51 due to inferior construction. I picked up another on ebay last night for pretty cheap, so I'm going to build that for rc(but not fly it yet, gotta learn more first).

I bought a Molt Models P-38(on the suggestion of a member here, thanks!), and will be assembling that next. I have a few questions about it though. First, it has a 38" wingspan, and 29"? length. On the site it list 10-12oz AUW. I'm comparing that to the Guillows P-38 rc conversions, that are 40" wingspan, and most of those are weighing in a ~30oz AUW. What's the difference? Can the Molt Models hold more weight? Does the 2" of wingspan difference allow an extra pound of weight? I've looked at the 3 part thread here on the MM, but the builder doesn't know the weight(and I haven't read all 950+ post).

I also want to run a different motor combo, I've been considering running 2 park250 motors, with 2 10A ESC's. Will this be too much? The motors are lighter than the compatiable brushless motors listed on the MM site. I considered dual park 180's, but that seemed to be a bit underpowered. I'm thinking that the 250's will allow me a little bit extra weight.

I won't be flying this plane until I get more experience either. My girlfriend is getting me a 607 Catalina RTF to practice some one, from the description and look of it, it will be a good beginner plane.

Thanks!
-Daniel
srt8madness is offline Find More Posts by srt8madness
Last edited by srt8madness; Dec 22, 2011 at 12:32 PM.
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 05, 2011, 03:28 PM
Registered User
danrc's Avatar
Rockford Illinois
Joined Jan 2008
2,327 Posts
Hi Daniel, I'll be building this one soon too. My sense is that the 250's will be nominally sufficient. I will be looking for some more power out of mine so I can tow up some retract assemblies/etc. Good luck with the build. I started a thread on mine, feel free to follow along. What P-51 did you have? I also have the Mountain Models P-51 socked away. I've read wonderful things about it.
danrc is online now Find More Posts by danrc
Reply With Quote
Old Dec 05, 2011, 03:32 PM
Neophyte hacker
portablevcb's Avatar
Albuquerque, NM USA
Joined Sep 2003
15,743 Posts
You have found the problem with most Guillows kits. They are a bit overbuilt and have heavy wood.

Molt's design uses light balsa and is designed to be light. Hence 12oz is not unreasonable.

I would not put more power in it than recommended. MM stuff all flies great on the recommended power.

More power means more weight. More weight means you need to reinforce the frame which means more weight. Then you'd need more power, which means more weight..... Pretty soon you end up with a 30oz airplane.

charlie
portablevcb is offline Find More Posts by portablevcb
Reply With Quote
Old Dec 05, 2011, 03:40 PM
whiirrrrrr
srt8madness's Avatar
United States, TX, Houston
Joined Nov 2011
785 Posts
Quote:
Originally Posted by danrc View Post
Hi Daniel, I'll be building this one soon too. My sense is that the 250's will be nominally sufficient. I will be looking for some more power out of mine so I can tow up some retract assemblies/etc. Good luck with the build. I started a thread on mine, feel free to follow along. What P-51 did you have? I also have the Mountain Models P-51 socked away. I've read wonderful things about it.
I just saw your post in the funbuild thread a few minutes ago, and was about to contact you, but you beat me too it lol. Thanks for the confirmation on the motors. I have the Guillows P-51 flying kit. I picked one up for $5 at a resale shop, made all my mistakes with it, and now just bought the exact same kit off ebay for $25. I'm still $17 cheaper than on Guillows site . I'm not great at taking pictures, uploading them, and writing dialog, so I most likely won't post a ton about mine, but I am looking forward to following your thread. I hope you don't mind me interjecting with a question/comment/suggestion in your thread, although I'm sure I'll be the one getting the most benifit learning from you! I'm getting out the
srt8madness is offline Find More Posts by srt8madness
Reply With Quote
Old Dec 05, 2011, 03:43 PM
whiirrrrrr
srt8madness's Avatar
United States, TX, Houston
Joined Nov 2011
785 Posts
Quote:
Originally Posted by portablevcb View Post
You have found the problem with most Guillows kits. They are a bit overbuilt and have heavy wood.

Molt's design uses light balsa and is designed to be light. Hence 12oz is not unreasonable.

I would not put more power in it than recommended. MM stuff all flies great on the recommended power.

More power means more weight. More weight means you need to reinforce the frame which means more weight. Then you'd need more power, which means more weight..... Pretty soon you end up with a 30oz airplane.

charlie
Thanks for the reply. I want to get away from the IPS-A gearbox, just because I guess. I'm having difficulty with learning how to read a motors output, there are so many different ratings by different companies & websites that it becomes a blur. And don't get me started on propellers. I believe I'll have it figured out by the time I need to purchase the components though.
srt8madness is offline Find More Posts by srt8madness
Reply With Quote
Old Dec 05, 2011, 03:44 PM
MPP
In Unusual Attitude Recovery
MPP's Avatar
Danbury CT (DXR)
Joined Oct 2005
2,152 Posts
That's correct Charlie.
Quote:
More power means more weight. More weight means you need to reinforce the frame which means more weight. Then you'd need more power, which means more weight..... Pretty soon you end up with a 30oz airplane.
I happen to have a 32 Oz. Guillows P-38 so I resemble that remark.

The molt will be a floater and fly real nice. If no one has recommended it yet. try to get a simulator. Much easier to learn to fly and when you crash on the sim you laugh instead of cry.

Best of luck,

Mark
MPP is offline Find More Posts by MPP
Reply With Quote
Old Dec 05, 2011, 03:50 PM
whiirrrrrr
srt8madness's Avatar
United States, TX, Houston
Joined Nov 2011
785 Posts
I've gotten steady advice for the sim. I've been playing with the one at the LHS, and I have a car club friend(another expensive hobby) looking for his old copy to give me. Thanks

-D
srt8madness is offline Find More Posts by srt8madness
Reply With Quote
Old Dec 05, 2011, 03:54 PM
Neophyte hacker
portablevcb's Avatar
Albuquerque, NM USA
Joined Sep 2003
15,743 Posts
FYI, the IPS is good for 15-20W max. So, any of the smaller motors will work.

The problem with the smaller outrunners is they need to run small props.

You might get away with the Park 250 on 2 cells, but, it is still a bit too much power.
portablevcb is offline Find More Posts by portablevcb
Reply With Quote
Old Dec 05, 2011, 03:59 PM
Obviously I'm a "Minus Member"
buzzltyr's Avatar
USA, MA, Longmeadow
Joined Jun 2003
1,828 Posts
I built the MM/Molt P-38 shortly after it was released, quite awhile ago. The limiting factor for motors is the space designed for the battery, which is small. You really will need to see what battery will fit in the center pod, and then pick your motor system based on the battery mAh. When I built mine, it had brushed GWS IPS motors and a single 20 amp ESC (the power system the model was designed around), and flew but required pretty much full throttle. With today's lighter, more powerful brushless motors, you can substantially overpower the model for much less weight. The other consideration will be the lighter motors may require some additional work to get the CG where it needs to be.

Thinking about it, the battery may not be much of an issue, as today's batteries are much smaller and lighter and have a much higher energy density (mAh/gram) than the ones available when the Molt P-38 was designed.

Mark
buzzltyr is offline Find More Posts by buzzltyr
Reply With Quote
Old Dec 05, 2011, 04:03 PM
The "pro" in procrastination
Steve85's Avatar
Canada, ON, Kingston
Joined Mar 2004
2,765 Posts
I've had good success running IPS A drive motors on 3s with the GWS 7x6 two-bladed prop. The combo draws 2.25 A, for around 25 watts per motor, producing almost 7 ounces of thrust with good reliability.

I'd be tempted to try the same set up using GWS 7x3.5 three-blade props, since I seem to recall the MM P-38 being marginally powered with the stock IPS S drive on 7 round cells.

Hey str8, you should enter your build in the Funbuild

Steve
Steve85 is online now Find More Posts by Steve85
Reply With Quote
Old Dec 05, 2011, 04:06 PM
Registered User
danrc's Avatar
Rockford Illinois
Joined Jan 2008
2,327 Posts
Daniel,
I'm planning (for better or worse) to go with Hobbycity's Blue wonder motors (24 gram; sold as HXT 1300kv) and a pair of counter rotating 3 blade props. I have some experience with the setup, so I'm not too concerned, but Mark is right, this plane has some space constraints, and every gram on either side of the CG counts!
You're doing the right thing, ask questions, build, try new things, succeed/fail, try again.

My first scale builds were of guillows planes (DR1 and a small hellcat) success was limited to single flights or parts of flights, but every second of the process is rewarding.
This plane should be much much easier a subject, even if it's multi engine.
Welcome to the scale forum btw. Hopefully you get hooked.

fyi, look up virtual aerodrome too. There's some good build/completed model photos on there as well.
danrc is online now Find More Posts by danrc
Reply With Quote
Old Dec 05, 2011, 04:47 PM
pilot
jeffh22037's Avatar
United States, OR, Bend
Joined Mar 2007
124 Posts
There are plenty of threads in the ParkFlyers forum detailing the Molt P-38 builds and motor combos.

The 'blue wonder' type of motors are a proven good choice.

I used pair of 25t Westport CD-Roms (like the blue wonders, a 22.7 mm diameter outrunner).
It flies well with those.

Some pics here.
http://www.rcgroups.com/forums/showp...&postcount=490

Jeff
jeffh22037 is offline Find More Posts by jeffh22037
Reply With Quote
Old Dec 06, 2011, 01:16 PM
whiirrrrrr
srt8madness's Avatar
United States, TX, Houston
Joined Nov 2011
785 Posts
Quote:
Originally Posted by danrc View Post
Daniel,
I'm planning (for better or worse) to go with Hobbycity's Blue wonder motors (24 gram; sold as HXT 1300kv) and a pair of counter rotating 3 blade props.
I'm open to any motors myself. I looked these up, and they are very affordable at $8 each. The park 250's are $32 each. Why the big difference in price?
srt8madness is offline Find More Posts by srt8madness
Last edited by srt8madness; Dec 06, 2011 at 01:23 PM.
Reply With Quote
Old Dec 06, 2011, 01:24 PM
Registered User
danrc's Avatar
Rockford Illinois
Joined Jan 2008
2,327 Posts
Durability I guess, although at 8 bucks they're almost disposable.
danrc is online now Find More Posts by danrc
Reply With Quote
Old Dec 06, 2011, 01:26 PM
Neophyte hacker
portablevcb's Avatar
Albuquerque, NM USA
Joined Sep 2003
15,743 Posts
Quote:
Originally Posted by srt8madness View Post
I'm open to any motors myself. I looked these up, and they are very affordable at $8 each. The park 250's are $32 each. Why the big difference in price?
One is sold by EFlite, one is not
portablevcb is offline Find More Posts by portablevcb
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
For Sale Mountain/Molt Models P-38 kit. Still sealed. $80 shipped CONUS. Tim Wolff Aircraft - Electric - Airplanes (FS/W) 1 Aug 02, 2011 07:16 AM
Sold Mountain Models (Molt Models) P-38 Kit (project) punkindrublik Aircraft - Electric - Airplanes (FS/W) 2 Oct 08, 2005 08:51 PM
FS: Mountian Models P-38 Kit NIB P-40 Aircraft - Electric - Airplanes (FS/W) 3 Feb 16, 2005 06:38 PM
Mike Molt P-38 Available at Mountain Models buzzltyr Scale Kit/Scratch Built 4 Aug 27, 2004 07:34 AM
Molt Models P-38 old p47 Parkflyers 3 Jan 01, 2004 10:52 AM