szempruw

After the wing was sanded to accept the sheeting, I made the 4 wing panels per the instructions. Maybe the wood shrunk after 20 years, but one panel on one side was a little small. Either that or the wing is too big. It really looks symmetrical and measures out ok. I added 5/8" to the front and figured I'd patch any missing areas once it was glued on. One could use another 1/2" to one of the 42" lengths. Maybe the curvature was not accounted for when sheeting materials were picked. Nevertheless, easy to fix. I used pins, wood glue and tacked down with CA. I wetted the wood a bit. The curve over the ribs isn't too bad except for the center front which had to be clamped down and it cracked. This fillet area will likely be sanded off anyway once I fit to fuselage.

The bottom sheeting gets trimmed to the ends of the leading and trailing edges. The top will overhang to create a fairing.

I ran large soda straws as lite weight conduit for the servo wire and I am planning for navigation lights. The Mustang also had "recognition" lights on the right wing. The straws are taped with aluminum duct tape which from experience, sticks well over time. Now's a good time to check wire lengths. All will enter the center of the wing and eventually connect into the fuse.

I'll prep and try building landing gear doors out of fiberglass and CF sheeting. I'll use the lite plywood die cutouts as a guide.

I don't want to seal on the top sheeting till I install the landing gear. They are still out for repair. I called and was promised an expedited look at fixing them.

mmorg1

My Feedback: (11)

Nice work. In November my Pica, mustang finally after a couple of decades died as a result of my over confidence. Pica flies better than the top flight mustang. I also did the "Bunnie" scheme. Good luck with your build.

szempruw

Thanks for your comments. I am enjoying the build albeit intensive, but that is 1/2 the fun for me. I am struggling, but have nearly completed the gear installation. The CJM gear I bought didn't "drop in" as predicted on the forums. I suspect they are "thicker" and perhaps upgraded. Can you share what you used and what the gear thickness might have been? I had to lower into the wing about 1/8" and I am now reinforcing the ribs as they seem too carved out just to make the wheel flush with the bottom of the wing. I'll post shortly.

mmorg1

My Feedback: (11)

First one had CJM Gear, still have them for sale on RCU, the second used robart gear. The gear on mustangs is a very weak point. once you are done building the wing reinforce the ribs and mounts with fiberglass cloth. The gear on the Pica are long so they transmit a ton of force to the mounts if you are a little sideways. I would also recommend making your tailwheel trail, rather than the scale setup.

szempruw

There's a lot to do with only the bottom part of the wing sheeted. I finally received my repaired retracts. It was a bad gear motor. While waiting however, I laid up fiberglass doors.

I first used the lite ply stamped out pieces to carefully trace the shape in position on the bottom wing per plan. I used some scrap see through Monokote and covered the area. The next step was to use thin 1/16" 3M masking tape to outline the doors. This would make a nice indentation in the layup from which to guide the final cut.

I laid up the fiberglass I had. I also had some carbon fiber sheet. The sequence and weight (ozs.) was .75 / 2 / 2 / CF / 2 / 2 / .75 using West system epoxy resin, 105/206. The final thickness measured about .050" to .055".

I carefully pried the layup to prevent distortion and with minor difficulty, it popped off. The 3M tape was pulled off and it was easy to trim with a band saw.

I also took some time to try and model the inside of the gear doors. Not yet sure I'll use them. Worse case I wasted some time. Best case is they stiffen up the fiberglass a bit. It will all depend on the gear installation.

szempruw

As mentioned earlier, I am using Century Jet retracts prescribed for the Pica kit. Hopefully the bugs are worked out now and as I said in another posting, you pick a vendor that you sense will work with you through problems. Someone told me that electric retracts for our small planes are not yet up to the reliability you have on full size aircraft. It takes time and commitment to get there. I've known CJM to be cooperative and respectful of my issues and I will continue to work with him and his products. Enough said, this is not a commercial as there are many vendors to choose from. The chosen one just has to be big enough and responsive enough to fix the problems when they occur.

Contrary to my forum research on other posts for the Pica Kit build, these retracts did not "drop in" following the Pica Kit's rail design. The Pica design accounts for the proper angle and assumes that the gear rotates 90 degrees as does mine. If you use Robart 85 deg retracts, you'd best cut the proper holes in the ribs before building the wing. I don't know what gear was used in the past, but these gears are perhaps beefier, or thicker such that they would not fit into the cut out wheel wells. I had to do two major things differently that took a lot of time. One, I had to lower the maple rails deeper into the wing rib by at least 1/8". I'm just glad I did not cover the top of the wing with sheeting as yet. It would have been a nightmare. At least I could get my hands in there.

Second, I started to favor the pivot point (and thus the gear) to be closer to the center of the fuselage. This inherently gives you more depth to bury the 5 inch wheel. Maybe the DuBro lite wheel is too thick? Yet even with that I had to hog out a lot of rib wood. So much so that I decided to reinforce Rib 5 with a sheet of G10. I also added triangle stock bracing. All was installed using Hysol. When I fiberglass the wing, I may also add some CF sheet in the gear area. All the forum posts say that the landing gear installation is the weak link on this plane. Hard landings can chew this area up How far can / should you go to build in strength? We'll have to see if this is enough. Maybe more experienced modelers of large planes can chime in?

One thing I know for sure is that I will have a lot more tinkering with this installation before all is said and done.

szempruw

I wanted to have a more scale like appearance so I thought I'd try the Second Generation RDS system. I realized that with the pocket, a removable aileron using a long piece of ,047" wire was out of the question. So, I cut the slots for the large Dubro hinges, installed the aileron pocket on the centerline and then fit the servos in wing pockets on plywood mounts I made. I'll glue in place once the finish is applied.

The only thing I don't like is that the gap on the wing seems a little too big because of the hinges. I'm going to try to bury the hinge more. Perhaps when I'm done sheeting the wing and sand everything down, I'll try to fit some balsa fairing strips to also close the gap a little more.

The 30 degree wipers give more than enough throw per the drawing.

capthis

My Feedback: (67)

Just picked up one of these kits I hope to build sometime. Enjoyed your pictures and can't wait to see more.

szempruw

Good luck to CapThis with his new Pica kit. I hope you enjoy the building as much as I do. A lot of what I'm doing is "first time" even though I've built many sport planes over the years. I'm struggling in areas that are new to me. Getting these doors hooked up and working correctly is a real challenge.

I'm back on the Gear Doors. I came across a problem with my intent of using HS 5065 MG Digital Servos and the Hitec Servo Programmer. I posted elsewhere and I received some good suggestions on how to fix. Basically the gear doors wouldn't open and close fully. The interface between the CJM sequencer was chopping the signal down and the doors wouldn't open and close correctly. I disconnected the mechanics and used the programmer to "overshoot" the servo through and when connected, the doors fully opened and closed. If interested in details see thread "Need Help with HS 5065 MG Digital Servo and Servo Programmer" on this forum.

I installed the gear doors such that they can be removed from the fuselage for maintenance. I used ball joints and clevis to connect the door. I built a small servo tray and slotted some wood so that I could also remove the servos with a couple of screws.

I'm going to focus on the attachment of the outer gear door and yet another new challenge. The aluminum block of the gear is sticking up too far. While trying to bury the wheel deeper into the wheel well, the gear rails could have been down further by about 1/16th of an inch. A cautionary note to new builders here. The repercussions of earlier build decisions affects the outcome down stream!

I bought some scale outer gear door arms from Sierra and installation of hinges and arms will be next. The flying season is approaching so building may wane till Fall. Way too much fun!

capthis

My Feedback: (67)

I do like building but this and the Vailly FW-190 kit I bought will be my first warbird attempts. I've always been a giant scale aerobat, or profile pilot/builder so this will be a new venture for me as well. I need to decide on retracts soon as well as a motor. I went with Sierra for my FW-190 project and probably will go with those for this kit as well.

I hear you on flying season coming up I have a few projects to finish so I have stuff to fly this summer!

szempruw

First, thanks to those who comment on the build suggestions. I'll keep them in mind.

After a long hiatus of summer flying, I managed to fix up the shop and start the P51 build again. I focused on the main doors and their fitment to the Pica kit using the CJM retracts I chose. As noted in earlier posts, there isn't a lot of room. The gear is big and I have to take liberties with scale which I am calling "pseudo-scale" not even semi-scale. Oh well, as long as it looks ok

I previously showed how I built the fiberglass doors and a rough detail of the main doors. I am now adding a fit of the outer gear doors. The first 3 pictures show a rough process.

The Main doors as I roughed them out didn’t fit at all. The wheel is too high in the gear bay and the problem of fitting them was elusive. Finally I thought of putting contact sandpaper on the wheel and spinning it from underneath. I purposely left the top wing skin off because I just had the feeling I’d have to get my hands in there. This allowed me to spin the wheel and apply pressure to sand away the interference. Slowly the Main door came down level. See picture 4.

I sealed the balsa wood and I started to prime the surfaces. My goal is to finish with an AlClad or Testors aluminum paint finish, so this will take awhile to prep. Maybe in my next post I’ll have it done to show. I’ve never tried to paint an aluminum finish before so this will be an experience for me. See picture 5.

Hopefully when all is done and mechanically mounted, I’ll test it mechanically and get to finish putting on the top wingskin. This has been a challenging and for me, a tedious part of modeling. I still worry about landing gear strength and now whether the servo has enough strength to hold the Main door shut while flying. Perhaps I worry too much!

szempruw

Murphnator, (Post below) Thanks for the encouragement. I just started to remodel some of my basement so I got strapped for time. Since I have plenty of planes ready to fly, I'm going to rekindle the building effort and keep this effort going as much as possible. I used this spot to edit a double post I did by mistake. Maybe a little out of step, but hopefully all is forgiven.

Any questions, albeit what I would do different, or why I did what I did, just let me know.

BTW, I contacted web support because I'm running into a website problem. I can edit small posts, but seems like larger posts are problematic. The site won't allow minor edits by showing an editable "preview" screen with large posts. The entire screen is blank for some reason. I don't know if this is a CPU memory issue or what. Small posts will allow minor editing. I'm just a stickler for proper typing and I cut and paste off MS Word. Something is not working right. OK, just a small rant but I'd like to be clear on what I write. Maybe the website tech guys can help? Maybe not.

In the meantime, I edited this post problem by cut and pasting from scratch. The posts don't like the embedded pictures I had in post #36. All is well again.

Murphnator

Hey! Glad to see your back in the shop! I took on one of these that was partically built, had wing framed with LIKE gear installed, and the fuse was framed up with a tail wheel installed. This is my first giant scale build and my first gear door/sliding canopy build. The kit came with the Pica scale cockpit, vent door, after market nose cone and sliding canopy. I just sheeted the top of the wing today.
I too was struggling with the build, so I started to look for build threads and found yours very helpful, but I was disappointed when it stopped.
Keep up the great work I look forward to the rest of the build!

dryverman

My Feedback: (2)

Hey Murph, welcome to the RCU forums!

Keep plugging away at the Mustang...

szempruw

Likely one of my most challenging model efforts on this build has been to fit the landing gear doors. I like the words "Pseudo Scale" because that is about the best I can do. I got bogged down with house re-modeling and the summer flying season. I really missed working on this so after hitting a wall last February, I just started again to get over this hump.

The pictures crudely show what I had to do. The key pictures are:
T31. The use of the Down and Locked "Amp-out," made by Wikes RC for D&L, is a type of switch that is a must. Without that little electronic piece, I'd go nuts tweaking the gear up and down. I used a 7.4 volt Lipo to drive one gear at a time for fitment. (FYI, the first one they sent me failed, but they sent me a new one. Nice people.)
T32. I used door scale-like outer door linkage from Sierra. It has some adjustment capability and it fit the 1/2" strut, the key factor. (Again, no commercial, but this is a nice piece.)
T33. The way to hinge the outer door was elusive, and I finally figured out to try putting the hinge on the removable hatch that gives service access to the retracts. A couple of the pictures show the large Dubro nylon hinge I used drilled out and attached with 2/56 screws. Between it and the linkage, there is a little "forgiveness" as the gear settles in the locked position.
T34. When all was fitted, the fiberglass doors laid up on the wing initially, were too high and uneven. That forced me to laminate more 1/16" balsa sheeting to the wing and then sand it even to the fitted doors. If you look close, you can see I added from the center to about 2 inches past the gear. All had to be block sanded and made flush with the original sheeting. I spent a lot of time adjusting the linkage fit before deciding I had to laminate to make this a smooth airfoil.
T35. & T36. I have the clamshells clipped and show the door articulating into the open position. I know my controller works, but I'll soon set it all up and check the door sequencing action.
T37. This shows the gear full down. (or up from point of view.).
T38. This shows the gear installed and I will likely add carbon fiber to the mounts to reinforce the maple gear. As mentioned earlier by others, the gear is the weak link and I am trying to build in some strength now.

With this fitted, I'm going to look at any last gear door bay esthetics and then finally close up the wing by adding the top sheeting. This will finally let me finish the rough building and sanding the airfoil shape.

szempruw

I finally got my priorities straight and got back to working on the P51. I built another plane and did more basement remodeling. I missed working on this plane. While I can get my hands in there, I added some balsa webbing to form the gear bay walls. It's not scale, but again pseudo scale. I'll plan to paint this area green. This work allowed me to finish the top wing adding the skin and making access doors for the flap servos.

szempruw

After I trimmed the wing skin flush, the next instruction told you to leave 7/16” to 5/8” over the flap. My error was of no consequence because I wouldn’t want a 3/32” sheet overlap anyway. I decided to laminate 1/16” balsa sheets with epoxy to plywood sheeting so that I could get a hard, sharper edge. (See picture, W1)
I cut the laminate a little oversize to the pocket and realized I wanted to make it flush with the wing skin and the flap. Until I fitted the flap to the wing, I couldn’t have anticipated the need to change the geometry of the flap to receive the laminate or any skin in this area. So I performed a little surgery on the front of the flap to allow for the thickness of the laminate. (See W2)
My heavy ruler served as a good backstop for my Dremel tool to route a clean edge. I trimmed the laminate to fit the tapered pocket. (See W3 and W4)
The indented flap needed a vertical piece of balsa sheeting and a new piece of skin on top. (See W5, 6, and 7.)
The pocket was fit with the laminate and I ensured there was a gap so the laminate wouldn’t bind the flap in the raised position. To ensure clearance I temporarily laid a length of balsa sheeting on the flap. (See W8 and 9.)
I supported the flap from underneath so that the flap was tight against the wing. I then glued the laminate in place and weighted the laminate down until set. (See W10 and 11.)
The next three pics show the flap travel and the fitment of the laminate. The width of the laminate at the wing’s root is bigger than the plan recommends and I noticed that flap is fully covered in the down position. The original design would have left a gap. Besides, looking at full size pictures, this modeling is a little more scale looking. The plans recommend 2 ½” flap travel at the wing’s root. (See W12, 13 and 14.)
I added 7 supports for laminate at each rib location. The plan suggested scrap 1/8” plywood. I made sure the fillets were rounded and wouldn’t bind when the flaps moved. (See W15.) The fitted flaps fit the airfoil pretty well, but a little light sanding will clean up the airfoil. I will plan to use a little gap filling putty and sand it all smooth before I laminate with fiberglass cloth. (See W16.)

szempruw

I worked on shaping that big block. You tack it on, then shape it and remove it to hollow out the inside. I knew I was going to add navigation lights but I needed a way to work out attachment and servicing it. I had teardrop lenses that I bought on the net, so I trimmed them down and made a 1/8 in. plywood plate to insert and glue into the end of the tip. I already installed large straws in the wing ribs to act as a conduit. I made a reflective plate out of aluminum and drilled a hole to match the minor diameter of a 5mm LED in the center. I drilled two holes in the plywood, one larger and offset to pull through the major diameter of the LED. I recessed another hole to fit the flange of the LED. I also slotted this hole for the wires. This sandwich locked in the LED with two screws into the teardrop and the assembly. Once I was sure it would work, I glued it into the wing tip. I made sure I could fishtail the LED from the landing gear bay to the wingtip. From there I could ultimately get into the center of the wing.

The light isn't too bad, but I can polish up the aluminum reflector if I need to later. The Nav lenses were from a vacuum form part from Meister Scale's sister company called Aero Accessories Ltd.

szempruw

I wanted to put in another scale feature since I was putting in navigation lights anyway. On the full size plane on the starboard side under the wing there are 3 colored recognition lights, amber, green and red.
I found these really neat chrome plastic headlamps as a kit for a Traxxas RC car, part number 6784. 5mm LED's fit and snap right in. I was able to find 5mm LED's on eBay, but 10 or 20 was the minimum order. Now I have a lifetime supply. They were about $6-$8 in bulk. for each color. They are rated for a 9V battery. Not too bad considering.
I cut a hatch hole and positioned 1/8" plywood supports for the lamps. The screw holes allowed me to put in 4-40 T-nuts and allow for easy removal and servicing. I positioned the edge of the lamp bezel to be just below the surface of the hatch cover. The hardest part, after making the .020" G10 cover flush was to align and cut the holes for the lights to show through. I'm going to use clear monokote to cover the holes, and maybe use punched out circles to help create a scaled ring look.
I can easily fish a few inches and route the wires down the conduit I installed for my aileron servo wires.

Lucky405

I just wanted to say awesome work i to have a pica 5scale mustang but I cannot figure out what the C-O-G is would you be able to tell me what it is

mine is going to be powered by a brison 3.2 (52cc)

szempruw

Lucky405, See this post or search for it in RCUniverse. I've been advising a 2-time builder of what I'm doing based on my calculations. If you need more info, let me know.

http://www.rcuniverse.com/forum/rc-w...e-p-51-cg.html

szempruw

Per instructions, it was time to mount the wing. Since the wing was sanded well, I wanted to work on the wing fairings soon. When I checked basic measurements, I started to fear the incidence was off. I don't have a incidence meter that big, but talking with a club buddy, he recommended making a jig. I copied the W2 ribs and added 1/8" all around. When I cradled it in the fuse, I could measure easily to the F22 crutch which is the plane's datum line.

Seeing this, I had to carve down about 3/8" in front. The maple blocks were already installed. I also found at app for a smart phone and used it to check the stabilizer incidence. I was 1 degree positive. Although the instructions /plans say 0 degrees, 1 degree was added to the full size plane so I think I'll be ok with the stab incidence.

Once I carved down I was able to use a Stanley 3/8" wood dowel centering jig I drilled the dowel hole in the wing, inserted the jig and pushed forward to make my mark. I epoxied the dowel in the wing, aligned the wing tips and drilled the mounting hole. And yes, I checked to make sure wings were level with the stab.

Now, staring at it, it's starting to look like a plane!

szempruw

The full size plane has some prominent wing fairings added after the wing is attached. I wanted to highlight this area and decided to use 1/64" plywood to make this shape. I have a 1/5 scale engineering plan of the full size plane and I made a rough template out of that score-and-break plastic sheeting. I had to lay out a panel line to locate it in the approximate area. I followed a basic technique for making the fairings I found in Model Airplane News by Nick Zirolli. It uses a 1/32" plywood sheet and a carbon strip to form most of the edge. Carbon doesn't like to bend around curves very well. After gluing it down, I made fillets and then planked with balsa strips. I used a light weight Bondo like fairing compound from Fibre Glast. They make some nice products for modelers. It sands easily and worked well to finish the edges. I'll use balsa and this compound to shape the belly pan. There is no real good way to make this union of wing and fuselage scale, so "pseudo-scale" will have to do for a removable wing.

tailskid

My Feedback: (34)

VERY well done sir!

warbdluvr

Fantastic build ! Your work is exceptional. Ill be watching this for sure as I have the same kit patiently waiting its turn on the table.