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Old Aug 20, 2004, 09:02 PM
Registered User
Saint Cloud Municipal, Minnesota, United States
Joined May 2004
37 Posts
p-51 twin

ok heres one for gws fans.How about taking two gws p-51's and making an p-82,or xf-82.its two 51's fused together,and kinda looks like a p-38.think it could be done?
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Old Aug 21, 2004, 12:46 AM
Crimson Swine...
Australia, VIC, Romsey
Joined Jul 2003
230 Posts
Zip:

Mate, there are a few threads on the RCGroups - try Twin Mustang and F82 in your searches. A few tantalising pics but little in the way of detailed build or flight reports. There is also a very interesting "Twin Zero" which flew very well.

I have two P51's ready to go to make into a F82. The purists will tell you, quite rightly, that the F82 looks like a Mustang but is a completely different aircraft. The fuse is quite a bit longer aft of the wing root (and a different shape), it had the taller VStab of later Mustangs (H model P51 I think) and the HStab between the tails is moved up higher. There are a number of other differences but I'm politely ignoring those and, as you suggeted, literally joining two P51D's at the hip.

My plan is to use a Clark Y shape airfoil in the centre section of the main wing, hopefully to add some extra lift and reduce some of the troublesome handling that the thin laminar-flow wing (faithfully reproduced by GWS) has at low speeds. It might perhaps look a bit odd (and require some surgery on the inner wing root mating areas of each fuse) but it shouldn't be evident apart from head on. Noting the P51 horror stories here on the `Zone, if it helps keep the thing in the sky, I'll live with it! HStab is a no brainer, but the various threads report that the F82 is very pitch sensitive, and that the size of the elevator is critical. My Corsair runs minimum throw and D/Rates, so where we cut the HStab will be critical. Still working on that one.

This baby will need to be driven on and off the ground with some authority, so I am heading down a 400C/3S lipo route. I'm still fiddling with the fuses to make the bigger 400 fit. The 400 will work but needs some surgery under the motor stick (no cowl so once the motor is in, it's in there for good!). I'm out on a limb with the gearing - I am recycling the D gearboxes from my PT17 and TM400 (the Stearman gets an EPSD 350 when my airmail package arrives from ALLERC, and the TM got a Mabuchi QRP motor upgrade courtesy of the helpful lads at Aircraft World). My plan is to start with the lower gearing, match it to a GWS 1080x4 prop, and see how that tracks. I want as much authority as I can get, at all throttle settings, and I'm happy to sacrifice top speed for throttle sensitivity - especially on finals with flaps. The slippery P51 shape should help with it being fast enough for a Parkflyer.

I'm currently project managing where everything goes - i.e. how many servo's, which side do they live on, one esc or two, single battery, etc. At this stage, I am steering towards a 5 servo (Ch1 - R/Ail, Ch2 - Elev, Ch3 - ESC, Ch4 - Rudder (linkage between the tails down aft), Ch5 - Flap (on/off on my HITEC Eclipse7) and Ch6 - L/Ail). I will set each aircraft up with a separate power unit, with it's own battery. I thought about a battery in the large cylindrical radome between the fuses on the LE, but I have some concerns with the engineering (and weight) of mounting that and keeping it on there in the event of a hard landing or a crash. One battery in one side could work but I'm also concerned about axial balance. Easier to duplicate a self-contained system running each aircraft. One ESC per aircraft, with a joiner through to a single plug into Ch3. TX will live in one side with two servos, three servo's will live in the other side. This is screaming out for retracts but the UC on the P82 is very different to the P51. It's quite a complex set-up, and was brought right in almost under the fuse at the wing root. KISS principle applies here (keep it simple stupid), so fixed UC to start, incl steerable tail wheels, and then see how she flies. I've super-detailed too many aircraft and watch them fall out of the sky to be getting too clever too early!

A very helpful friend is going to hotwire the airfoils for me soon. I'll keep you posted.

Cheers,
Mick
Canberra, Australia
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Old Aug 21, 2004, 03:45 AM
Specialist in Crashing
UK, Loughborough
Joined Jan 2004
1,106 Posts
I'm looking at making an me-109 zwilling so thats another to try. Was thinking of making a brand new wing for it made out of depron with a carbon fibre strut accross it to rienforce. I am not sure how it will fly compared to the P-82 or that twin zero. I have decided to use the stock 350's in each and then use 2 8 cell KAN650 packs. I think that should give enough power for the props. I think i will try that duplicate plane idea aswell. Dan
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Old Aug 21, 2004, 04:06 AM
Crimson Swine...
Australia, VIC, Romsey
Joined Jul 2003
230 Posts
Me109Z Zwilling

Dan

Good call. The Me109Z Zwilling (twin) was my other choice. The GWS Me109 is, by all accounts, a far more stable platform to start with, so a twin version would benefit from it's inherent flyability straight from the get-go. I was thinking about asking my buddy if he's swap his Me109 still in the box but in the end I stuck with the P51/F82, mainly as the Me109Z is a single seater - the unmanned fuse has a metal fairing in place of the cockpit. The F82 also has a lot more wing area between the fuselages, which should help with calming the wild beast down!

I was going to hotwire the centre version from pink Depron, including a channel for the stiffening strut to line up with the standard channel, and back that up with "dowels" made from 3mm CF rod epoxied between the wing sections to give the whole wing some torsional and shear strength at the joins. After all, the GWS DC3 wing uses a jigsaw approach and seems plenty stiff enough.

I have the 350s it came with but having recycled two 400 motor combos from my Bipes and having suitable 3S batteries from same, I will use those. The 1080x4 may be a bit chancey (calcs from the GWS specs for the D gearing are not good) but I'll experiment as I get closer.

You might even get retracts to work on the Zwilling. The 109 has the wheels very close inboard (in fact, they pivot from the fuse - which is why they lost so many Me109 singles in landing accidents). Here are some 3 views. The Me109Z looks like "Gustav" derivative, whereas I think the GWS kit is an Emil, but ignoring the spinner the early version of the Zwilling looks similar to the standard Me109 fuselage shape. I've got the same problem with accuracywith the P51D/F82 but at the end of the day, it's a flying model not a museum piece. I've got to get the thing to work first!

Good luck.
Cheers,
Mick
Canberra, Australia
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Old Aug 21, 2004, 04:39 AM
Specialist in Crashing
UK, Loughborough
Joined Jan 2004
1,106 Posts
Thanks for this info. Please do keep me updated on how you are getting on. It might tak em longer as i need to get the money first :P If i can get it about on par with the normal warbirds on performance i will be very happy. You think i might need a little flap to be able to land it slow as you have got a higher wing loading? Now gear would be an impressive sight to see! The me-109z does feel quite a bit different to the me-109 in IL2:Sturmovik (pc game) Ill keep you updated on any progress. Dan
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Old Aug 23, 2004, 01:43 AM
Thanks Wilber and Orville !.
sonic liner's Avatar
San Jose Cally
Joined Jan 2004
1,036 Posts
My twin zero was going to be a p-82 first but the mustangs were not out
yet.
A couple of points to remember.
1- The greater the distance between the fusalages the more gliderlike
the plane.(To much wing area)
2- The best way is to use one e.s.c. and one receiver along with one battery
pack. How you balance it lateraly will affect its flight performance.
3- You can use the trailing edge of the center wing portion for a flap.
4- Be frugal with the paint unless going brushless and even then lighter is
better.
5- Have fun with it....its not that hard to do...just sounds like it.


Pete Lane
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Old Aug 23, 2004, 02:46 AM
Crimson Swine...
Australia, VIC, Romsey
Joined Jul 2003
230 Posts
Pete

Thanks for the excellent tips. Your twin Zero was the actual impetus to get me thinking about the Twin Mustang. I'll go through your points in order:

1. Centre airfoil. Good point. I was hoping for a lifting body style approach with the centre airfoil. I was thinking the more gliderlike the P51 at low speed, the more chance of survival!

2. The "one of everything" approach. Good point. It would certainly save on weight (and cost) I am driving 2 x geared 400s though, so the battery is probably going to have to be a reasonable sized 3S LIPO. Actually fitting all the other stuff in the other fuse to balance the battery in the roll axis is starting to become a squeeze, plus I'm starting to think of CofG issues in the pitch axis. I am weighing all the various combinations before I settle on the best balance.

3. Central Flaps. Yep, that was the plan. Are you using that for flaps (flap?) in your Twin Zero? If so, how wide is your flap, and how much travel did you allow for full flap?

4. Weight. Good point. That was steering me along the one of everything approach (like yours) until I started to run into problems balancing everything axially.

5. Cheers, half the battle is sorting out the project management before you start.

Thanks again,
Mick
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Old Aug 23, 2004, 03:17 AM
MINE!
Mick Molloy's Avatar
Australia, VIC, Point Cook
Joined Jul 2003
3,186 Posts
My friend has made one from 2 mustang kits by S and B Models
I'lll post some pics later tonight of the twin but as a teaser here is the normal S and B kit
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Last edited by Mick Molloy; Aug 23, 2004 at 03:31 AM.
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Old Aug 23, 2004, 05:59 AM
Crimson Swine...
Australia, VIC, Romsey
Joined Jul 2003
230 Posts
Thanks Mick, nice pic. I'll be interested to see how wide the centre section is on your friends' S&B Twin (noting Pete's comments above about building in too much wing area). I'm going with the scaled down measurements right off the data sheet - actual "flying" width of the centre airfoil is 66% of the main outboard wing.

Also keen to discover any project management hints, especially on set-up.

Cutting the wings in two weekends time. Will try to get some pics in here then.

Cheers,
Mick
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Old Aug 23, 2004, 08:01 AM
MINE!
Mick Molloy's Avatar
Australia, VIC, Point Cook
Joined Jul 2003
3,186 Posts
The picture as promised
Here is the thread for it not very long but.
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Old Aug 23, 2004, 12:35 PM
Thanks Wilber and Orville !.
sonic liner's Avatar
San Jose Cally
Joined Jan 2004
1,036 Posts
Looks like everyones doing or have done their homework.
My flap is one inch wide with 1/4 of travel and it works well.
Keep a chugging along on your projects as the sound of the flybys
is awsome.
Hope to see the maiden pics. soon. Please consider the option of either
a bomb or center fuel tank to center the weight and hide some of the
components as cooling will be easy this way.Thats how i set up my T.Z.
Cheers to ya! Pete
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Old Aug 25, 2004, 03:38 AM
Crimson Swine...
Australia, VIC, Romsey
Joined Jul 2003
230 Posts
F82 Twin Mustang Radome

Pete

Mate, thanks for the tip, and the encouragement. I was contemplating putting the battery in the big cylindrical radome that the F82 had dead centre between the fuselages but the engineering kinda scared me off. The F82 radome hangs wa-a-ay out in front, and it doesn't appear to be hanging on by much, so engineering a mounting system to keep the thing attached to a foam wing looked somewhat daunting. Check out the pics - seemed like it was going to be a case of chasing weight to make it strong enough to survive a hard landing. Haven't given up on the idea but rigging a spar lengthwise to hold it all up could be quite a challenge.

Is your TZ still flying?

Cheers,
Mick
Canberra, Australia
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Old Aug 25, 2004, 01:31 PM
Houng-wen Lin
GWS4CEO's Avatar
Shijr, Taiwan. DungGwan, China. City of Industry, California.
Joined Sep 2001
19,445 Posts
I am sure that you may easily Mods from the GWS P-51 kits.
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Old Aug 25, 2004, 04:07 PM
Crimson Swine...
Australia, VIC, Romsey
Joined Jul 2003
230 Posts
Mr Lin

Thanks for the input. The GWS kits are very good basic "building blocks" for projects such as these. Plus the range of spare parts (motors etc) will allow this to be upgunned relatively cheaply (brushless is still very expensive here in Australia).

If the P38 twin wasn't coming along soon, then perhaps an ME109Z Zwilling or an F82 Twin Mustang might have been a good project for GWS R&D. Might have had greater universal appeal than a Twin E-Starter.

Cheers,
Mick
Canberra, Australia
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Old Aug 25, 2004, 08:52 PM
Thanks Wilber and Orville !.
sonic liner's Avatar
San Jose Cally
Joined Jan 2004
1,036 Posts
Hey no problem Mick.
Yes the T.Z. is still flying after 200 flights a little hanger rash
only gives her more of a warbird look.
The center fuel tank was the answer to mounting my battery(one)
and also robust enough to hand launch her as well.
Keep up the good work and spirits. Pete lane
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