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-   -   Pica 1/5 Scale Mustang Build 2015 (https://www.rcuniverse.com/forum/rc-warbirds-warplanes-200/11613030-pica-1-5-scale-mustang-build-2015-a.html)

szempruw 02-07-2015 06:29 AM

Pica 1/5 Scale Mustang Build 2015
 
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I started a "bucket list" project, the build of this Pica kit I bought over 20 years ago. I've been out of the hobby for awhile and decided to jump back in. I've used this forum extensively to look for building ideas and to get caught up on newer technologies. After restoring an MGB, one thing I learned was to have as many parts on hand before you start so that you can avoid waiting for parts and maybe shorten the build process a bit. Besides, some of the planning is fun, anticipating what's next and dreaming of how it will look. I found the RCM magazine review on line and I wanted to mimic the picture posted in that review. On top of that, I found I couldn't fit all of "stuff" in one shot. I couldn't get high enough! See the attached pre-build pictures. I managed also to email and correspond a bit with one of the designers of the kit, Jon Tanger. He was gracious enough to take some time and answer some basic questions I had about CG and overall weight. My thanks to him and he seemed to get a kick out of the fact that his efforts were still being appreciated. I like to build. I think it's half of the fun of this hobby, not just the flying.

I've already started the build and thought I'd share this effort to see if anyone else is out there. The kit is well organized and is an intensive build, There are some minor things to improve upon like the control linkages, yet that is a fun challenge also. If anyone cares to share comments, great. At 65 being "tired and retired" I know you are never to old to learn. At worst, this becomes a diary that might be fun to look back on in years to come. I've found about 40 forum members who built this kit over the years. Some have responded and I am grateful for their encouragement. I also appreciate the long summaries I've found with good suggestions of what to do if given a second time around to do it again.

My build started the first week of January, 2015. Let's see how long it will take. I've kind of locked into a color scheme and plane to try and scale, "Bunnie" flown by Pilot Roscoe Brown Jr. (March 9, 1922 – July 2, 2016.) I'm hoping the red tail scheme will help with visibility if and when I actually get to fly it.

Regards, Wally

szempruw 02-13-2015 07:18 AM

Fin, Rudder, Stabilizer and Elevator Build
 
6 Attachment(s)
The Fin, Rudder, Stabilizer and Elevator were built per plan instructions. I'm anticipating elevator linkage changes to eliminate a gaping hole in the fin to make it look more scale like.

First thing I noticed is that you build 1/2 of the item at a time. Lay the sheets down and then add support structure for the skins. This theme is carried out throughout the build of the features and being such a large model, that works well. Once again, the build is intensive, but I am really enjoying the build.

I planned to build in the elevator and rudder counter balance features. I thought it best to build without and then cut out the features and glue them back onto the opposite location. It was tedious to build a box out of the cutouts. Maybe building them in initially would work better. I didn't add the triangular hole at the base of the fin as will be seen why in the next post group. After skinning, I rough sanded and planned to hinge after I put in the counter balance features. I'm new to posting so this is an experiment with adding pictures.

szempruw 02-13-2015 07:45 AM

Elevator Linkage
 
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A friend recommended using Sig Manufacturing's centered control horn as I lamented about the big hole I found in other Pica Mustang builds found on the net. After building per plan, I carefully drilled holes for SIGSH554 and I epoxied it in place. I gouged room for the nylon horn and strove to make sure I was at the centerline of the hinges. I used heavy duty hinges and thought I would install using one continuous length of .047 piano wire. This way I could install the hinges inline and then remove wire to cover the surfaces and then add back. I then hinged / sanded the control surfaces to ensure adequate throw. I measured / checked fitment of the elevator joining rod through the fin area and I used a Dremel tool to round out the plywood around the rod area that passes through the fin to about 1/4" or less.

The fin is buried about 1/4" into the stabilizer per plan. You are asked to cut away this top stabilizer surface. Making room for the center line of the rod through the fin was easy enough and the results were good. At this point, with trial fitment, it was easy to see that I could fillet the elevator by adding a triangle and skin to make this area fit closer to the fuselage as it is on the full size plane. I've added a picture for comparison.

Striving for hidden linkages on a scale plane is a nice goal. This design already called out for hidden elevator linkage. The use of this type of horn, a small design modification, made for a cleaner look.

szempruw 02-13-2015 08:25 AM

Top Fuselage Build and Skin and Engine Mount
 
11 Attachment(s)
I'm into the 6th week of the build, about 30% done. I'm beginning to appreciate the build / design of this kit more and more. The build scheme of 1/2 at a time works really well on such a large plane. The top half of the fuselage is built by laying down a spliced 1/2 x 3/4 balsa strip on each side of the fuselage. It's called the F22 "crutch" and in reality it becomes a datum line to the fuselage build. Stab incidence, engine location, pushrods, all can be located using this feature.

With the crutches laid down, all formers are added per plan, perpendicular to the building table. I am anticipating a different engine mounting scheme than showed on the plans. When this plane was designed, the ST 3000 was a rail mount option. Today an EVO gas would rail mount. I chose the DLE 35RA for my plane. I received good recommendations from guys in the club who found this engine to work well and have enough power. Besides, at worst case, I should be able to swap out with a DLE 55RA if it build too heavy and I need more power.

My thanks to a Brit, Phil Fearn who documented a nice build project of the Pica Mustang. http://forum.medwaymfc.org.uk/view_t...m_id=42&page=1 He made and used a box technique as an engine mount and I'm going to copy that. For now, I decided to leave the crutches a little long anticipating movement of the engine mounting box. Why? To build (pun intended) on Phil's idea, I want to wait till the last possible minute to install the engine firewall so that I might be able to balance the model by moving fore or aft a bit. Every once in the tail has to be offset by lead in front. Since I will add a retractable tail wheel, I can account for this weight moving the whole engine forward. We'll see later if this strategy bears out.

The box I built is 4 H x 5 W x 10 3/4 L. It fits all the way back to the F7B, so for right now, that seems plenty long enough. Gluing in place may become a challenge. We'll see later.

I'm making another small modification to the instructed build. I'm anticipating installing a cockpit from www.dbalsa.com and I'm not yet sure where to floor will go. I'm leaving out the balsa floor detail to add later as determined by the kit once it arrives. (A side note here. None of the cockpit vendors give you real good guidance as to placement of these parts. i.e. where does the seat go, the control stick, the canopy crank etc. relative to the plane? You've got this big hole to put something into, but no dimensions from the nose or tail. I found a see through drawing on the web and I had it blown up to 1/5 scale to use it as a guide. Again, we'll see about that later.)

Skinning and sanding the top half went well. All is being prepped for checking engine box placement, and per instructions, gluing on the stabilizer at 0 incidence to the building table.

szempruw 12-05-2015 11:49 AM

Tail Wheel Setup
 
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The tail wheel retracts forward. Making it steerable presented a problem. The retracting arc suggested the need for springs, but that didn't work as well as I've seen in other posts. I received a suggestion to hook up toward the rear and steer from rudder. I set this up with cables and after trial and error, it worked well. I did this while I could get my hands in there to make changes before I sheeted the back end. I started with a larger G-10 horn, but I'll cut it off since the closest hole works well.

szempruw 12-05-2015 12:43 PM

P51 Sliding Canopy
 
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Before I sealed up the back end, I thought it prudent to work on the sliding canopy. My thanks to forum members who responded for suggestions, especially Leroy Gardner. I goaled to use the canopy itself to form the turtle deck. I used balsa sheeting to form the bottom. The drawings give and idea how I did it. I insert molded 1/2" x 1/16" aluminum frame work into a lite two-part epoxy mix from Smooth-On. Very nice product and can be colorized black. The canopy rails are slit 1/4" sq. aluminum. The canopy split area will be cut once the canopy is glued in place. A separator piece of plastic will allow the framework to come apart. I found some small 2x5x2.5 mm bearings that fit nicely onto 2-56 screws put into cut-down control horns. These fit nicely into the 1/4" aluminum rails and helps the framework slide easily. I decided to use a Firgelli linear actuator and that fitment prompted me to dry fit the Dbalsa cockpit accessories. Again, all this was done so I could figure out the actuator travel before I closed up the back bottom end with sheeting. Building the sliding canopy prompted a side build excursion into the details of the cockpit interior. This will be a post by itself.

szempruw 12-05-2015 01:25 PM

P51 Cockpit Details
 
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I ordered (twice) the dBalsa cockpit interior. At first the Topflite ARF version seemed too small. The Ziroli version was too big and so I re-ordered the smaller one. I have to say that the documentation that came with both versions was edited from other kits, had errors and basically no guidance relative to install location. The problem comes when you try to locate things like the seat, the control stick, the instrument panel etc. I used a "see thru" jpeg of the P51 blown up to 1/5 scale to try and use features on it to locate the components. Being a technical writer, I know I'm not perfect, but I struggled for hours through the written instructions finding one mistake after another. The graphics are poor with a few errors. The side control box has rudder and Aileron control graphics, not ELEVATOR. Regardless, I used what was given and augmented some details. I found some full size P51 graphics being sold and it was easy to put into a Word Document and adjust to 1/5 size. Since I dry fitted everything, I proceeded to paint all as suggested in dBalsa pictures. I started to get consumed by the detail and had to quit. I began to feel like the ghost in Beetlejuice who built a replica of the small town knowing he couldn't visit it any more!

szempruw 12-05-2015 01:40 PM

Fueselage Rear
 
5 Attachment(s)
The pics show the rear bottom being sheeted and closed up. I'll still have to add tail wheel doors. There's going to be a lot of sanding to shape the whole thing after I finish building the front end. If you notice inside, I used some large straws wrapped in duct tape to make conduit for the wires. It would be tough to route wires after the fuse is sheeted.

BarracudaHockey 12-10-2015 10:57 AM

Moved to appropriate forum

BarracudaHockey 12-10-2015 10:59 AM

Love it, looking great, keep us posted on the progress!

Ram-bro 12-10-2015 05:44 PM

this is one kit I wish I had...its also on my bucket list It is or was probably the most scale of the mustang kits on the market, definetly more scale than the TFGS Mustang. I will be watching with great interest..

tailskid 12-10-2015 07:29 PM

Built one 'way back' in the 80's I believe...never did finish it - sold it 3/4th done! Wonder if it ever flew....

szempruw 12-15-2015 09:19 PM

Engine and Cowl
 
8 Attachment(s)
I turned my attention to the engine mounting and cowl. Following advice from fellow club members, I decided to bite the bullet and fit a DLE55RA. I built a new firewall and added it to my original box. The resulting engine box I built with the DLE55 was set as far back as I could without losing glue support on the front former. The net result was that I had to build out the fuse just a bit with an extra cowl ring mounted to the fuse. I had to account for the engine thrust angles about 1.5 deg down and 1.5 deg right thrust. This meant I had to affix the spinner plate, with a 1/8" spacer to the front of the cowl so I could mount to the engine and lock in the position of the rear cowl ring, the new one added to the fuse. I also installed the F1 plywood nose ring because I haven't yet decided to slit the cowl horizontally. The cowl is built with 8, 10-32 nylon wing bolts that will go into the fuse. This cowl attachment allowed me to close up the front, add filler sheeting to account for the cowl offset and then rough sand the entire fuselage.

tailskid 12-15-2015 09:22 PM

Nice 'recovery' :)

szempruw 12-15-2015 09:30 PM


Originally Posted by tailskid (Post 12139590)
Built one 'way back' in the 80's I believe...never did finish it - sold it 3/4th done! Wonder if it ever flew....

Tailskid, yes that seems to be a pattern on the forums. People start them and don't finish them. The kit is labor intensive, but I am enjoying the build. It really makes the Winter season go fast. At the pace I'm going now, I just might get it flying this next Summer. It will all depend on how bogged down I get on the covering and details.

tailskid 12-15-2015 09:33 PM

My trouble was I was moving and had it about 90% complete - even with panel lines, full cockpit, etc.....broke my heart. I did build and fly their 1/5 T-28 AND the 1/6th T-28.....and as a matter of fact have a NIB 1/5 T-28 sitting in the garage! Doubt I will ever get to it :(

Jerry

Duplicator41 12-17-2015 07:28 PM

Nicely done.

Cheers,

szempruw 01-06-2016 02:34 PM

Tail Wheel Doors
 
2 Attachment(s)
I found and used and old set of Phoenix gear hinges for the tail wheel. I made a slot that fits two planks of balsa sheeting that I first glued to the hinges. Then I fitted to the plane and checked for easy movement. I won't glue these in till I fiberglass the fuselage. I'm having trouble with my electric retracts. I sent them back for repair. Funny how just cycling them for trial / fit purposes could cause them to go bad. Maybe I just bought a lemon. We'll see. Now I'm going to work on decorative exhaust stacks and start building the flaps.

szempruw 01-18-2016 04:47 PM

Flaps Geometry Test
 
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My first question looking at the Flap design was "Why is there a difference in the pivot point at the root vs. the wing tip end of the flaps?" I couldn't wrap my head into it so I decided to make a prototype out of cardboard and hinge music wire. I kept the tip pivot at 11/16" and made two holes at the root, 1 1/16" and 11/16" set back from the leading edge. The distance from the bottom was 5/16" on both sides.

Well the answer maybe obvious to some, but I determined that the pivot points on the plans account for the wing's taper and change in radii. The pics show the results. If not hinged offset at the root, the lowering of the flaps won't stay parallel to the top of the wing's trailing edge This let me start the build. The flaps won't be exactly scale like but it will use the hardware given, a large nylon L shaped bracket. Other forum comments suggested adding a third hinge rather than pivot at only two points. I figured out a way to do this.

szempruw 01-18-2016 05:11 PM

Easy Flap Build With Hidden Linkage and Removable Flap
 
8 Attachment(s)
A friend of mine, a master builder, acquainted me with scale hinge building techniques, adaptations from an article that was in Model Airplane News. He also modified this technique to include a carbon fiber tube as a hinge and CF rod (or music wire) as the hinge pin. It's a bottom type hinge with a 4-40 swivel link I figured that if I made a balsa strip laminate of 3/32 and 1/16" thickness, I could lay the 1/8" CH tube on top and then surround it with 1/8" balsa strips. I would use the locations of plan's hinge points as a guide. The height off the bottom would be the measure 5/16" noted on the plans side view and as done in the flap test. I made the laminate 5/8" wide and could easily cut pockets in the ribs to glue in place.

I picked a spot in the middle and made a G10 hinge. It will be glued once the first two pivot points are set. The CF tube is cut out at this point and rod or wire used to hold the hinge in place till the glue sets.

The two ends call for poplar blocks to be glued, attachments for the L bracket the root and pivot support at the wing tip end. I cut those back to account for the CF balsa laminate hinge.

szempruw 01-18-2016 05:56 PM

Flap Servo Location and Hidden Horn
 
10 Attachment(s)
W2 Rib already had some notches in it if one were going to put in one servo controlling both flaps with a bell crank. I transferred these holes to W3 Rib and decided this was good spot for the servo linkage.

I took a WAG at flap throw thinking I would have 7/16 - 15/16" of servo throw on the control arm and an arm length of 5/8" to 11/16" which would allow final adjustments once the servo was installed for real. The drilled horn hole will be slightly ahead of the hinge pin to minimize vertical travel of the connected linkage. I easily get 40 deg flaps with this setup. Careful not to get too short an arm since you can get more throw than you bargained for. I drilled the arm closer to 9/16" by mistake. Still plenty of adjustment, especially if you add in servo travel limits by the radio.

I planned the horn's location and made some G10 ribs and cut them to fit the balsa laminate. I epoxy glued them to some extra balsa ribs. Maybe over-kill, but I thought it would be easier to glue them to the sheeting. The spacing between the G10 accounts for the 4-40 swivel assembly.

The pics show the near completed flap, trailing edge sanded down to accept the sheeting. I just have to layer on the top sheeting. The front shows the swivel rod sticking out an oval shaped hole. I used a lock nut and epoxy for the swivel screw as there is no good way, short of surgery, to access this connection after sheeting. My friend says it is robust and will outlast the plane! I hope he's right. What we do for scale appearances!

I'm happy with the results so far. It was an easy build, a blend of Pica's design and a more scale like finish. I now have 3 hinge points and an easily removable flap. And in case you are wondering, I'll either use a little L bent into the end of the music wire captured by the large nylon L bracket or I'll drill a guide hole in the L bracket to hold a CF rod. Either way, the flap can be glassed, finished and re-installed at will, a nice feature.

70 ragtop 01-18-2016 06:59 PM

Nice project!

szempruw 01-26-2016 10:01 AM

Wing Build
 
8 Attachment(s)
I took a day to cut and lay out the plans for the wing. I decided to use the lite ply ribs, but cut out rib holes to lighten up a bit. Others recommended making the ribs outboard of the landing gear out of 1/8" balsa. It would be lighter, about 9 grams a rib. I also planned out holes for servo wires and yes, navigation lighting. I made landing gear front ribs W4, 5 and 6 out of 1/8" plywood to strengthen this area per build recommendations of others. I used plywood webbing here also. More people recommended that you add balsa webbing to the rear of the main spar, which I think is a good recommendation.

Surprisingly, the build without the sheeting took about 2 days, (I work slow) but overall much faster than the fuselage. I thought I'd try the RDS hidden linkage for the ailerons. I ordered the 30 degree wipers as the aileron throw travel is recommended at about 15 to 20 degrees. I laid out the location on the plans. I'll be able to servo limit or have adjustable rates if needed. I'll build access doors from the bottom and use the HEMS (Harley's Easy Mount System) servo mount technique recommended by the website. I'll build in plywood platform and likely blind nuts to secure.

Overall, I now get an appreciation for the size of this plane. I have home-made 8 foot x 40 in. work tables. BTW, I bought a sheet of 1/2" Homoste 440 sound board from Menards to be able to pin to the table. I saw this on the forums and it is a great idea.

A comment on the instructions. The leading and trailing edges should be "symmetrically" glued to the ribs. I had to catch myself as the building tendency was to pin to the plans and glue wood. I just supported the edges with wood blocks and glued on as instructed. Also, I don't know how you can "pin" lite ply to the table. Perhaps someone with stronger thumbs than me! I just weighted the ribs down onto the trailing edge jig. There's enough wood to trim, cut and sand to size to the ribs.

szempruw 02-03-2016 08:28 AM

Wing Center Section
 
4 Attachment(s)
The rib building of the right wing half took about a day. Joining the wing and figuring out how to finish the front center section took a lot longer. One thing about this kit is you get a lot of block wood that needs to be carved off. A word of caution in that there are not enough instructions on placement of the front blocks. Also, the "sand and shape to the plans" instructions leaves one wondering how. I just imagined that the sheeting needs an almost flat surface to glue on. I also reflected on the fitment to the fuse. I still got in wrong and cut too much off. I had to glue on more block wood and reshape. All I can say is favor the bottom of the wing while adding the blocks. This part must blend into the bottom of the fuse and be rounded to match the contour. You end up with a hump on the bottom front of the wing. After I glue on the sheeting, I know there is some fillet area that will have to be ground off, but I didn't want to again take off too much wood at this time. You don't round out the leading edge till sheeting is added anyway. You also have to shape the leading edge in the center so that you can judge how much to sand/carve off.

szempruw 02-03-2016 08:58 AM

Flap and Wing Linkage Fitment
 
5 Attachment(s)
With the sheeting still off, I thought it be a good time to add the pivot points and flap linkage while you can easily get your hands in there. The front leading and trailing edges are sanded to match the rib contour. I added the flap's L brackets and drilled out the tip-end hole to accept the 1/8" CF tubing I cut off from the flap. I was tempted to drill the L bracket differently, but I stuck to the plan's location as seen from the top view. This worked out well for keeping the rotation of the flap parallel to the top of the wing as I tested this before with a cardboard model. I drilled pretty close, but still likely a 1/32 off. Mounting the L brackets accurately is tough and drilling the tip-end pivot hole required a piece of oak drilled as jig to make sure you drill 90 degree square. Luckily I have a small hobby drill because getting in a normal size drill is not going to work here. I installed the servos and tested the linkage. My WAG stated on an earlier post for the horn connection wasn't too far off. If I would change anything, I'd favor adding more arm length, as much as possible, yet still be able to connect the swivel linkage. Also, the linkage bound up a little and I couldn't get enough flap angle deployment. Using the existing hole in the W2 rib turned out to be futile. I had to relocate the rails so that the rod linkage was centered more to the attachment at the horn. This puts the servo as far down into the wing pocket you can get. If you go too far, your sheeting won't cover. I'm getting about 40 degrees now. I'll test again later. Maybe I'll post a YouTube video. I'm setting up my Taranis radio with an sbus for flaps and ailerons on channels 9 through 12 and mixing in some elevator trim with slow flap movement to make it scale like.


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