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Lockheed P38 lightning - Part 2

by Phil Niewand

Plan No.697

Features Construction Articles

Plan Detail:
Plan No. 697
Price: AU$85.00 (3xSheets) 
plus P&H (AU$7.00 within Australia).
Moulded Canopy: AU$27.50 plus postage.

Order Details:
Order On-Line

By Phone:
(03) 9333 5100
ByFax:
(03) 9333 5099
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Airborne Plans Service: 
PO Box 30 Tullamarine,
VIC, Australia, 3043

One of John’s conditions for me making this plane was that I was not allowed to paint it in any camouflage paint schemes. It had to be silver! So a bit of Internet surfing had a plethora of colour schemes to choose from. I kept away from anything with invasion stripes or fully painted spinners, because of all the masking involved and the spinner would look very second hand after a few starts using the electric starter.

The cockpit was detailed out by printing off a dash from the computer and just gluing it to the dash panel. The scale pilot was painted up and glued to the base just in front of the seat headrest. A couple of mock air tanks went behind the seat to finish the job off. I thought it was a good idea not to go too overboard on the detailing until I knew it was going to fly! That must be the pessimist coming out in me! Before starting the covering job, I made up some dummy turbo-chargers and pipe work to go on the top of each boom. Remember to pick the right system for your particular type of P38 as there were so many different types throughout the model runs.

While I was in the detailing mood, I made up a mass balance weight for the elevator from aluminium sheet and two pieces of 6.5mm dowel, which leads me into that subject. If you have a good memory you’ll remember that I made a 60 sized Mustang four years ago for Airborne. I used the brown paper and PVA glue method to give the plane accurate panel lines, covers and hatches. This really turned out great and didn’t really add much extra weight to the finished model.

The brown paper is simply applied by dipping the pre-cut sections into a mix of 50/50 water and PVA. Start from the underneath and the rear and work your way forward, slightly overlapping each piece. The paper has a shiny side and a dull side, so remember to always keep the shiny side up for a much smoother finish. The paper will follow the curves easily and can be stretched to make it fit into tight spots and compound curves. Once the whole plane was covered, it was given light sand with some 240 grit paper and then coated with another layer of the glue & water mix. Another light sand with some 400 grit will have surface ready for painting. The canopy needed to be trimmed to size to get it fitting properly. I left it off till I had done the covering job.

I used the end of a piece of 1/8 inch brass tube to press into the paper surface to make indents for the quick action Dzus fastener used around the cowling removable panelling. The rest of the panel flush riveting was done with the end of a printer cartridge refill nozzle. This made very small little round indents in the paper to simulate the flush riveting. I just spaced them out at about 4mm intervals to end up with something that looked pretty close to the real thing. If you put them any closer they just don’t look very realistic and just become too cluttered up.

As the plane was looking to be tail-heavy, I decided to shift the two servos the were in the left (port side) boom further forward to help with the weight distribution because I could see the need for a big chunk of lead up in the nose if I did nothing. The fibreglass radiator covers were epoxied in place on each side of the two booms after moving the servos. They fitted snugly in behind the wheel inside the well. A ply plate was made up and glued in place to hold them there. I just used the edge of a thin file to make the panel lines in the radiator covers and the tiny end of a Dremel piece to make rows of rivets on each of them. A couple of air inlets for the turbo-chargers were shaped out of balsa block and glued in place on the outside of each boom just under the rear of the wing. To hold the removable wing ends in place four small pieces of aluminium flat were screwed to the outside edge of the main wings top and bottom. Small self-tapping screws went through these and into some double ply gussets that were built into the wing. The balsa was cut away under each strap to make it flush with the wing surface so that they weren’t too noticeable.

PAINTING:
It is very hard to find realistic aluminium paint. The one I ended up using was Dulux Aluminium Kill Rust. I used an airbrush to apply the paint after thinning it down with turpentine. Only using enough paint to get a good cover, this took two coats to achieve the desired finish. Once it had dried properly I had to try some fuel proofing clears. I had a go with Estapol satin finish, but it really dulled the surface too much. I ended up using urethane gloss to get a realistic finish. Using extra coats around the engine areas and where the oil residue would end up down each boom.

FINAL DETAILING:
The canopy had thin strips of brown paper glued in place to simulate the bracing framework. I then used a syringe to place tiny drops of PVA to make rivet lines over them. A tiny paintbrush and a steady hand had them painted silver.

The canon and machine guns were made up from pieces of 6.5mm dowel and the flutes were drilled along them. 3.2mm aluminium tube was then cut into 3mm lengths and glued on the ends of the four machine gun barrels. Matt black paint was then used to paint them and then smudged around the guns to simulate gunpowder blackening. The sides and around the engine cowls were also given the treatment with a smudge of black to dirty up the areas. The turbo-chargers were then painted up with a dark grey paint and the black used to dirty up their exhaust exits along the top of the fuselage. The wing tips, and top and bottom of the rudders was then masked up and painted a bright red.

My mate the sign writer, owed me a few favours for fixing up his motorbike, so his wife was able to computer generate some great stickers for me to finish off the detailing. A coat of clear over these to stop the edges lifting had the Lightning nearing its time to take to the sky. I still hadn’t fitted up the doors for the retracts but I was itching to just see it fly.

FLIGHT TESTING:
The week before the maiden flight had me doing all the calculations for the C of G position. After working it out using 25- 33 % of the mean average cord, it needed to still have 200grams of lead in the nose to get it balancing in the right spot. The battery pack went right up the front of the nose next to the lead weight. The final weight, less fuel, ended up at 12 lb (5.44 kgs) on the button, with a wing loading of 32oz/per sq ft. This really had me worried! Most of the planes I’m use to are all around the low twenties.

Sunday dawned upon us and the sun was shining. Final checks and after lunch it was off to our clubs field for the big maiden flight test.

The wings tips were fitted up and the tanks filled and just one last final check of making sure everything that might fall off wasn’t going to. A range check was carried out with the motors running and all was ready for the flying bit. The tanks were topped up and the Magnum 61’s were tuned to pull 10 1/2 thousand RPM on the 11x 9 props. We had one guy with a video camera and Matt Downes with his new digital camera all ready to catch the big event! I taxied down to the end of the strip to give myself a good long runway. Holding on to the tail, the motors were revved up and I said a few prayers (I’m not a religious person, but I thought it wouldn’t hurt!). The throttle was opened up and the P38 built up speed quickly and after only about 30 metres it went over a slight hump in the strip and as it crossed it, the Lightning was flying! I thought to let it settle back on the deck, but it just wanted to keep going up, so I let it, letting it gain height slowly as it accelerated to a good flying speed. Well if anyone had any doubts about its flying ability they were all squashed then and there! If it was going to stall and roll in, it should have happened as it was taking off then! As the nerves settled, I remembered that I didn’t move any trims to have it flying straight and level. That incidence meter really did its job! A few gentle high circuits, just to get the feel of the twin, had me smiling and yelling out to the guys that it was a pussy cat to fly! The retracts were tried next and they didn’t want to come up (a small air leak), so I just flew around for about 6 or 7 minutes. I tried out a loop and a roll and then did a few low passes so the cameras could get a few close ups. Now for the landing! The throttles were backed off to about 1/4 and the flaps were deployed, this made the plane just balloon up and not want to come down, another circuit to bleed off the height and set up for a landing. With the strip lined up, I brought the plane in over the edge of the strip at about a couple of metres . I wanted to have plenty of speed up for the first landing. Well it just kept going and going and didn’t want to touch down. By the time it did land it was going quite slowly and settled in on all three wheels at once for a perfect first landing.

Well, everyone gathered around and stood in amazement, saying things about the short take-off and how that washout really must work! They also commented on how stable it looked in the sky. Well after a bit of back patting and a bit of bull shit, the tanks were filled up again and a quick check over everything was carried out. Motors started up and taxi out again for another go, just to see that it wasn’t a fluke. Power on and taxied past the hump this time before applying full power and gaining more than enough speed before lifting off gently and climbing out in a slow curve. A couple of laps and then into a few consecutive rolls, just using some down to hold the nose up while inverted. The rolls look a bit funny, because of the twin booms, sort of barrelly from side on! Although they do look much better when coming in straight at myself, it must be a bit of an optical illusion! The stall test was tried next, with the plane a little dot in the sky the throttle was backed off and the nose lifted up to bleed off the speed. It had to slow down to well below where I thought it would stall, before just dropping the left wing and spinning one turn before righting itself. I had thought with such a high wing loading and very skinny tips that it would spin at the drop of a hat. The washout and good wing section really must work well together. No surprises for a good average pilot here. I haven’t tested out a single engine flight or landing yet and will have to try one out in the not too distant future.

I’m now fitting up the retract doors so I can take it up to Shepparton for the Mammoth Scale event on the 17th & 18th of September. With some bad weather over the past month I haven’t been able to get any flying in, so I’m hoping for a few good ones in the few weeks left before the event.

Well that’s about it from me! This is a worthwhile project for a fairly experienced builder, really flies beautifully and just looks so good in the air! Thanks to the Airborne crew for having faith in my ability to do the plan justice.

Use of incidence meter
Use of incidence meter to get all flying surfaces at the correct angle.

 

Foam Cowl Plug
Foam was shaped to start the fibreglass cowl manufacturing process. You can of course make yours out of balsa and ply. Airborne will have glass cowls and radiator covers soon.

 

Finished Glass Cowl
Finished glass cowl. Note the holes to allow cool air in and out.

 

Cowl is laid up
With the two piece mould made, the cowl is now laid up inside.

 

Cockpit detail
Cockpit prior to painting. Small details inside makefor a more realistic model.

 

Colour scheme applied
With the brown paper covering added, simulated rivets and panel lines were added then colour scheme was sprayed on.

 

Canons in the nose
The canon and machine guns were made up from pieces of 6.5mm dowl and aluminium tube.

 

Canopy frame with rivets
The canopy frame is made of thin strips of brown paper glued in place. A syringe then placed tiny drops of PVA to simulate the rivets.

 

Cowl
Finished fibreglass cowl with a very unobtrusive exhaust.

 

Under tail plane
Underside of the tailplane showing the rudder linkage so only one servo was needed for two rudders.

 

 

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