P-3 Orion preview - RC Groups
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Feb 27, 2002, 10:32 PM
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Eddie P's Avatar

P-3 Orion preview

Okay, now. I'm back to the old scale multiengine modelling tricks. I used an extra fuselage tube from my Convair 580 project to make a P-3 fuselage. I also made a L-188 Electra fuselage too, with the remaining fuse tube from the same project. I'm concentrating on the P-3 first, as I want to make sure it flies well before making the second model.

Using exact scale dimentions, the fuselage width works out to provide a 1:25.6 scale model. So, the wing span is 46.5 inches (stubby wing), and the fuselage is a tad ove 48 inches. With the MAD antenna (stinger on the tail) it gets to 51.75 inches total. I'm using 4 Jamara 280's running off one ESC and a 8XCP1300 pack. Final weight target is 35 ounces, and at 171 watts projected it will be about 78 watts per pound. That should be good enough for some nice non-scale goofing off, with 300 square inches of wing area (16.8 ounces per square inch loading).

It wouldn't be a bad thing if the final model looked like this (in my dreams... )
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Feb 27, 2002, 10:40 PM
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Eddie P's Avatar

Let the cutting begin!

The first step after drawing out my plans and getting all the dimetions down was to start in of the fuselage. Just like on my Convair 580 article I cut out three nose and tail cone profiles out of 2" thick pink foam. I cut them slightly oversized to make sure I didn't come up short on material. Then I glued the 3 profiles together with some Pica Gluit. After drying, I placed the center fuse tube against the nose and tail blocks. Using a marker, I outlined the circular shape of the fuselage tube and then went to work sanding the nose and tail sections. I then went to work on the cockpit window areas and using a lot of reference photos and 3 views, I tried to get the dimentions as close as possible. I used emery boards and sanding blocks to sand the window frames.
Feb 27, 2002, 10:45 PM
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Eddie P's Avatar
I then glued the slightly oversized nose and tail cones (one at a time) to the fuselage tube with Pica Gluit. After drying I used sanding blocks to merge the oversized pieces to the fuse tube. Some more detail work went into making the tansitions just right, and more cockpit windoe frame shaping occured. Then I built up the tailfeathers out of light balsa, to be covered in Monokote. I wanted this to be light!

Note the notch that the horizontal stab tucks into. The foam plug goes on top of the stab when installed, and then the vertical stab locks into slots cut into the fuse top and the plug.
Feb 27, 2002, 10:47 PM
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Here's the installed empennage.
Feb 27, 2002, 10:51 PM
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Eddie P's Avatar


Foam cores were cut, wire harnesses soldered up, slots cut for the wire harnesses, and carbon fiber strip spars were glued in place. At this stage the sub leading edge has been glued in place, and the cores have been prepped for the 1/32 balsa sheeting.
Feb 27, 2002, 11:07 PM
Ascended Master
Sparky Paul's Avatar
Looks VERY good!
The fuselage diameter relative to the wing area has always stymied me on those large airplanes..
I've had the opportunity to fly the full-scale.
It has more performance than you might expect.
Seriously overpowered, with 4000 hp per motor.
The California Division of Forestry uses them for air-attack fire bombers. A beautiful color scheme, if the grey of the usual P3 doesn't appeal...
Feb 28, 2002, 07:03 PM
Crazy Cessna Owner
Robbie d's Avatar
If the p3 turns out anything like the convair, it will be a masterpiece. I've considered the Orion myself, with mst other people doing Hercs, an Orion makes a nice change. How about a torpedo drop or sonobuoy?
Maybe I could get a hold of some plans for the wings and tail and give it a go myself.
Feb 28, 2002, 07:34 PM
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fuelsguy's Avatar
Nice looking ship. What wire size do you use from the fuselage to the motors? I'm building a Lancaster with speed 400's, in parallel,and was wondering what wire gauge to use for the runs. The outboard nacells are 18 inches from Centerline.
Feb 28, 2002, 07:52 PM
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Craig Logan's Avatar
Cool. How do you shape your fuses round? Lathe, hot-wire lathe, or carving/sanding/elbow grease???
Feb 28, 2002, 10:57 PM
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Rudderman98's Avatar
You never cease to amaze me! Can't wait to see her all completed. BTW, I expect a full flight report okay?
Mar 01, 2002, 09:25 AM

Re: P-3 Orion preview

EDDIE, My GOLDEN DREAM in R/C is building an
Electra II in Varig colors.
I Flew at least 50 times in this marvelous plane, in the Rio de Janeiro to Sao Paulo shuttle...
The howl of those 4 Allison still sound in my ears...

PLEASE, if you do it, may I follow u, here in Brasil and do the same plane in Varid colors?

Mar 01, 2002, 02:19 PM
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Eddie P's Avatar
Sparky- Yup, the Aero Union firebomber is surely a sweet looking P-3 color. I was tempted to go with this early on. Since I grew up close to the Moffet Field NAS I think I'm going to finish her up in the early hometown squadron colors though. You are a lucky pilot to have been able to fly a P-3 without having a 9 year commitment to uncle Sam for doing so!

Robbie- Thanks, I originally drew up the Orion a year ago but other commitments got in the way. I figured I shouldn't wait anymore since there seems to be a lot of interest in this field now, especially among Hurk afficianados. Mabey others like you would like to build one too. I'll keep you in mind for plans as soon as it flies.

Fuelsguy- I originally intended to use 18 guage from motors #1 & #4, then 16 guage from the merge of #2 & #3 and finally a short strip of 14 guage at the merge of the two wing halves to the ESC plug. I couldn't find quality multistrand 18 guage wire though. So I have 16 guage wire all around. I'll solder up a short run of 14 guage for the ESC to the wing right and left half split. The merge of the right and left half should see 19 amps, each center section prior to #2 & #3 motor will see about 9.5 amps max and the outboards will be about 5 amps each. The outboard wiring is overkill but better than bad light weight wiring. In your s400 model I think 16 guage multi-strand wire will be a good choice.

Craig- The center section is hot wire cut. There are 2 halves, and they are glued together. The walls are about 1/4" thick, and it's 2lb density foam. If you glass, you could easily use 1lb density foam. This was an original "cut" for the fuse, so I didn't know how light I could go before a chinsy structure resulted. I overkilled a bit on the 2lb foam. The nose and tail sections are elbow grease.

Rudderman- You are too kind. You bet there will be a flight report, good or bad.

Cesar- On my L-188 Electra I had been thinking about the Varig scheme myself, but I knew I couldn't do that to you! I'll keep that livery to you, eh? That is one of the best all time Electra paint jobs in my opinion, but the Brazilian background helps too.

So, I'll have further construction photos/updates later tonight.

Mar 01, 2002, 02:39 PM
You are really a gentleman, Eddie
But please, fell absolutely free to do it.
In my oppinion, this could be a worldwide homage to a flying legend and if you really decide to use this color scheme, it would be an honor to me.
I can even help you a lot.
I have original Varig's drawings with exact lines!
I can fax you if u decide so.
I kindly ask you only to allow me follow u and build one myself, based in your job.
It would be another honor to me, believe me !
Mar 03, 2002, 12:16 AM
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Eddie P's Avatar
Here is a picture of the wings, skinned with 1/32 inch balsa sheeting. The leading edges have been added and sanded, and the ailerons have been cut out. A Jamara 280 and prop is there for size comparison. The 2 thin plywood wing braces are glued into one wing waiting for the center section joint to be finished.
Mar 03, 2002, 12:31 AM
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Here the fuselage has been surface treated. The bare foam was treated with lite spackel and sanded to fill the small air holes on the surface. For the center section and the aft fuselage, medium weight silkspan was used, applied with "Varathane" brand satin water based polyurethane.

This was my first attempt using Silkspan. It works nice, but I'm very used to using .6 or 3/4 ounce glass cloth. Old habits die hard, so the nose section was glassed with 3/4 ounce cloth and the water based poly-u and blended into the silkspan because I had a harder time getting a wrinkle free finish with the silkspan. Both the glass cloth and the silkspan require the same amount of water based polyurethane to be sandable and allow for a good finish. After trying both prducts, it seems the weight would be similar too. It's a matter of personal taste. I was able to get the glass cloth to lay down better and had fewer wrinkles to sand out afterwards. I'm sure most would be able to get just as good of a result with the silkspan too. After final sanding it's impossible to tell where the silkspan is and where the glass starts, aft of the cockpit area.

You can also see the wing leading and trailing edge bulkheads installed. Between these is the wing saddle/center fillet. The right side has been cut to final shape, with the left side still having excess material that has been subsiquently taken off. Aft of the saddle you can make out the trailing edge fillets that merge into the wing when installed.

The wing panels have obviously been joinred and the small part between the wing and fuselage is the forward nacelle plug used in my first vacuforming attempt. The forward nacelles are .015 thick plastic (light). Since they are non structural, they don't need to be terribly strong. The aft nacelles are balsa and all 4 weigh in at .5 ounces total (not shown).

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