RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

More progress on the booms and gear. I have worked out the mounting plate and supporting structure for the mains. The port boom now has gear. As things go, the tire wound up dead center of one of my gear door formers. I'll work this out when I get them cut apart. As I have been doing all along, I'm making patterns of everything I cut for anyone who may want to try this.

You will see that I cut away some wing mount to clear the tire. This won't matter as I plan on mounting the boom to the center section permanently. They will just hold everything in place till the epoxy or Gorilla glue dries.

The other hole in the plate is for the throttle servo, accessed through the gear bay, as will be the rudder and elevator servos which will rest just behind the tire.

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

That is looking really good.. I can't wait to get them templates and start on my booms.... I have the wing just about finnished and I am in the middled of fiberglassing it.. What size wheels are you using? Also I have been looking for a formula for calculating Scale.... I notice in a couple of previouse posts that you refer to some of the mods your making are close to 1/7th scale, How are you figuring this out? I have a Three view that I want to have enlarged the size of this P-38 and that is why I am asking...

Thanks,
Brad

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Brad, the full scale P-38 J had a wingspan of 52'. 1/7 of that is 89 1/8" and our plane is just under 90". So I am using 1/7 scale as a very close place to start with all my calculations.

I have a book by Bert Kinzey on the P-38 called D&S (detail & scale) volume 58 part 2 (P-38J - P-38M). In it you will find lots of good pictures and three views but it also has a page of three views with all the major dimensions on it (missing in the Walk Around books). I got this book at Borders Book Store.

It is a simple matter to take any of dimension shown, and divide by seven, for our plane. For instance, the full scale main tire - 36", 1/7 of that is 5 1/8" which should be our main gear tire. I cheated that down a little to 4 3/4", still much larger than the ones in the kit. The full scale nose gear tire is 27", 1/7 of that is 3 7/8" and I am using one 3 3/4". Interesting that the yoke built into the Yellow Aircraft nose gear does not allow you to use the 1/6 scale size tire for that plane.

As far as the templates and instructions go, I am saving copies of every part I'm putting in her, but will wait till she is on all three gear before I release the stuff to make sure it all works to my satisfaction and I want to make sure my angles and locations are right for the mounting plates and all. I have to get her back on her feet and see how the static angle of attack is also. The top of the rudders on the full scale were 9' 10 3/8" and the canopy was 9' 9 5/16" off the ground when parked. Ours should be 16 15/16" and 16 3/4" respectively, or somewhere close, and I don't have the nose gear in yet, to test that. You can see from these dimensions how nose high she sat on the ground. The bottom of the rudders were only 2' 9 3/8" off the ground hence the need for those bumpers they had on the bottom!!

I may need to add the curve to the center pod as well, something I have been debating for weight considerations. But, on the other hand, that would give me a nice roomy place to install a good size air tank for the gear, not to mention how much better it would look with a curved gear door. I think I could blend the nose into the stock fiberglass nose cone and still make it look a lot more scale.

BTW, I'm using the Robart spring down air up nose gear for positive lock on the nose. Don't want to scuff the nice cone that comes in the kit.

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Gary thanks for all the info.. More than helpful, I figured it was probably simple division but I have not done much scale stuff so I thought it would be better if I ask to be sure.. Thanks for all the help and I am going to try and find that book as well as anticipate the templates.....

Have a great day.
Brad

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Back on the wings and engines. They are installed and the booms are fitin place. I had to notch both the leading and trailing edges for the tanks and tires respectively. I set it up on it's mains and it looks like everything is working out well and authentic looking. It will take a pretty long nose strut, but the full scale had one also. Still not sure about the bottom of the center pod. I am waiting for my nose gear to show up now. Can't do the gear doors till my hinges get here. In the mean time, I'll be working on the tail and controls, fairings for the pilot pod, and other things.

Those struts are 1/2" and I wouldn't want them any smaller. I think they look about right.

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Couple more shots of the wing work. Again, the CF wing tube goes past the boom and right up to the aluminum stock tube for the center section. I'm not worried about the notches.

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Although I am waiting on the offset hinges to show, I finished making the gear doors. I laminated them with 1/32 ply to give them strength and keep them straight. I left the skin long in the rear to overlap the aft fuselage for a nice look. The extra layers of sheeting in the front gave me the slight inset look they needed. They are strong and light. I now have the whole mess sanded and coated with Balsa Rite, in preparation for covering with flat Grey Monocote. When all the covering is back on, I will go to work with Rustoleum and make it look as though it has a few victories to it's credit.

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Now for those cowls. I am going to laminate tree layers of 6MM Depron to the bottoms, blend them into the fuselage, and then glass over the foam. They fit perfectly over the engines. I am going to have to mount the Pitts mufflers backwards, so as not to have to notch the crap out of cowl, but I will cut the tubes 1/2" or so out of the cowl and angle the cut toward the rear.

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Now for a question. All along my intension was to stay with the camo look and just improve on it with detailing, weathering, and invasion stripes. I am having second thoughts. I am considering the natural metal finish that most of these J models came in. I'm looking at a complete paint job anyway. What do you guys think?

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

I think the Aluminum look is awsome...And most likely easier to see in the air.. I am covering mine in Flight Metal... With the Virginia Marie scheme. You are making good progress and its looking really good.

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

I now have the cowls blended into the new shape on the bottom. The Depron and Gorilla glue worked great. All I have to do now is glass over the foam.

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Here is a picture of the Depron in place and held with stretch wrap. I let it sit overnight like this.

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Ram,
Something to consider, cmp arfs are generally polyester. Epoxy doesnt stick to that very well. You would have to use polyester reson to stick to it. I dont know if it would attack the foam.
Edwin

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Thanks for the tip. I was told by my glass expert that it would work. I'll double check that and post how it goes.

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Well, I have the gear doors on one boom hinged. It took three hours of tinkering to get them right. I learned a whole new language in the process. [:@] I'm happy with the result, but this is a real pain. I wish the hinges would swing the doors farther out and clear of the fuselage but I guess the way they work is more scale. Turned out the plywood skin on the doors is necessary because it is all that is left on the edge that slides past the fuselage, but it is still strong and rigid because it is thin ply.

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

If there is a way to make epoxy stick to polyester, I would sure like to know. That would be great for me. The one experience I had was on the first cmp spitfire I bought. I was using epoxy to glue in fittings for servo, ant guides, air tank and so on. During the finish up process those parts started poping off. Just didnt bond. I found that goop works great to hold those parts in. Sticks like snot on the finger, wont come off.
Edwin

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Well, I double checked with my friend who does fiberglass work. For years he had a model business building scale hydroplanes and was actually on the crew of Miss Budweiser and did fiberglass work in building and repair on her and drove the semi that hauled her. He is retired from all that and now is into planes. He made me the fiberglass sleeves for my CF wing tubes on this P-38.

He says that it is possible to use epoxy glass on poly resin glass, but not the other way around. In preparation, first clean the area with acetone to make sure all the mold release is gone, then rough it up good with 100 or 80 grit.

So it looks like I'm golden on these cowls. Doesn't matter what they are, as I'll be using epoxy glass.

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Here are the booms back on the center section. She is getting there. All the main gear doors are now hinged. The first set took 3 hrs, the second set took about 45 minutes. I'm thinking the nose gear door will also go much easier now.

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Wow, Impressed is an understatement. Very nice craftsmanship.

How are you planing on springing the LG doors?

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Glad you are enjoying it. I plan on using Yellow Aircraft 5/32 bore gear door air cylinders. One on each door. I'll put them in the front of the main gear doors and the rear of the nose door.

I've decided to give the center pod the same rounded treatment as the booms. Just seams a shame not to, now that I've come this far, and it will be easier than what I've already done. It will look a lot better, and make for a more realistic looking gear door as well. It will also give me the room I need, above the retracted gear, for the full body pilot I have for this ship, and the air tank.

RE: Nitroplanes 90" P-38 (1/7 scale) with 3 piece wing and more
 

Still dealing with the flu, but I've made some progress. I now have the cowls glassed. I have also added a round bottom to the center pod. Here is what I did. Never tried this before, but it worked pretty good.

-cut out the gear door opening in the stock pod, in the scale location
-taped over this new hole
-Put 2" blue tape around the sides of the pod
-covered the bottom with 'Great Stuff' spray foam
-after setting overnight, I removed the outside tape and cut the basic shape curve with a hack saw blade
-then I went to work with my 'Mouse' power sander and did most of the shaping
-I then used light weight Spackle to fill in imperfections and sanded by hand with 150 (did this 3 times till I had it the way I wanted it)
-then I taped the sides again and glassed the bottom with 5oz glass and Zepoxy.
-trimmed it back and removed all the tape and that is where I am now.
-next I will use the previous cut out for a pattern to cut the gear door out.
-Then I will remove what foam I have to to install the nose gear (still waiting on this to show up)

RE: Nitroplanes 90" P-38 (1/7 scale) with 3 piece wing and more
 

Here are some more pictures of the glass prep, and then the finished pod ready to sand after some cure time. I was able to blend the shape into the stock nose cone. It is actually very smooth but doesn't look that way in the pictures. It may be all the variations in shade from the foam, filler, and Epoxy. This whole pod project has taken about 4 hrs to this point.

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Very nice. Boy you sure are running the gambit on materials used. I like it.

Earlier you had said you were going to attach the mid section of the wing to the booms permanately, with GG or epoxy I think. Just thinking out loud, ok knowing my flight skills and your building skills, Why not make it removable? One of those just in case something goes terribly wrong, and you need to replace the center section or a boom. Might save a lot of cutting and replacing of glued members. Would have plenty of room up through the mains openings for hiding a fastner system along with what's already on top.

Last one then I'll let you go. In case you are looking there was an earlier forum on this bird, and someone was making a lot of the plastic parts from fiberglass and offering them for sale. Like the boom intakes and top supercharger covers.

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

GG, Glad you are enjoying the project. I am trying a lot of new things on this one to use on other projects. So far, everything I have tried has worked at least as well as I had hoped. yes, I did originally intend to do just that, but since, I have been rethinking that. Your point is a good one, but also, the tanks would be all but inaccessible with out removing the boom from the wing. I think I will go ahead and leave them removable but with some added fasteners. I would be very interested in finding those glass parts. I have seen them for the Royal P-38, but not this one. I'm going to make frames for the wing cover-turbo chargers, and make them removable as hatches for access to the wing bolts and glass parts would be better for this. Thanks for the heads up on that.

I have now added two more layers of glass to the area where the gear door will be cut. It should make a nice door. More pictures tonight.

RE: Nitro 90" P-38 (1/7 scale) with 3 piece wing and more
 

Couple shots of the belly after the glass work. Set it on its gear today and it looks like I'm going to need an 8" nose strut to get the proper angle of attack on the ground. This will also put the rudders about 5" off the ground (4 3/4" being 1/7 scale).