hfenn

While at the 2010 SMALL in Little Rock, I purchased a short kit for Select Hobbies PT19 .15 size control line kit (SCL-1) from Steve Adams.
http://selecthobbies.com/kitdata.htm On his site you will see a complete kit is available. I got a short kit, meaning I would supply the leading edge 3/8" dowel, 1/4" square balsa spars, 1/16" balsa wing center section sheeting, and a small piece of 3/8" balsa for the top front nose area. All hardware was included except control lines, handle and wheels. This design is based on the Sig Akromaster .15. I've had one of these for 27 years with a Fox plain bearing .15. It's had it share of bumps and inverted crashes. It is a tough airplane. It has been patched and tail parts reglued but has held up well over time. This is going to be a build thread rather than kit review, but I have looked it over and checked the fits and you will get high quality machine and laser cut parts as well as a well drawn full size plan sheet.

hfenn

Here I've laid out the fuselage parts. First you cut the 1/8" X 3/8" horizontal fuselage spacer to the needed two lengths and glue in place.

hfenn

Once glued together, blend the spacer into the bottom of the fuselage by sanding.

hfenn

Next, I glued in the 3/8" square maple engine bearers with five minute epoxy. I used the plywood fuselage doubler to mark the bearers and trim the fronts of them. A band saw comes in handy here.

hfenn

I like to taper (feather sand) the rear of the plywood doublers. It's not drawn this way on the plan, and Sig doesn't show this in their instructions for the Akromaster, but I think it will look better if you use a painted finished, and I know it will make this area easier to cover if using an iron on film. I epoxy on the doublers with 30 minute epoxy and use plenty of weight to get a good bond. Here, I've done one side at a time. Remember, the doubler with the rectangular engine space goes on the right side (as sitting in the cockpit) of the fuselage.

hfenn

Next I round and smooth all edges except where the tail parts mount. Then I mark hole locations for the engine mounting bolts and fuel tank retainer (I'll be using J-bolts). Next I drill all holes needed in the fuselage. This is easier done now without the wing or tail on the model. You have to drill through for the landing gear stop dowels and the lg slot at the le of the wing cut-out. A drill press assures I'll get them straight through. This can be done with a hand drill, but go slow and make sure you go vertically through the wood.

hfenn

Liberate the tail parts from the 1/8" laser cut balsa sheet. You will also find the W-1 wing rib in this sheet. You will also need the stabilizer platform from one of the 1/16" sheets. Here I glue the fin parts together and the rudder parts together. I will not glue the rudder to the fin until later because I will be film covering the model. Cut the 1/8"X1/4" spruce elevator joiner to the correct length and glue in place. Mark a center line on the stabilizer platform and the stabilizer to aid in getting them square to the fuselage. NOTE: in the photo the rudder is NOT glued to the fin. I only pinned it on to check the fit.

hfenn

Glue the stab platform to the fuselage. Assure that it is square. Glue the stabilizer to the stab platform and assure it is square to the fuselage both ways. Next, glue the fin module on top of the stab making sure it is vertical. Now we have something to look at and make airplane noises.

stuntflyr

I do profiles similarly but I use blind nuts on the inboard side for the engine and tank and recess them, then cut the bolts off a little shorter than flush so I can glue the doubler on without holes. Just makes it a little cleaner looking.
Nice model, great thread, thanks for posting the pics. I love pics.
Chris...

hfenn

Thanks for the tip, and thanks for looking. More to come.

hfenn

Now it's time to build the wing. You will find a pair of pre-notched shaped trailing edges. Note that the spacing of the notches is different on the two ends. The ends that have a pair of notches closer together will go in the center. I have marked the 4 ends that will be cut off with an X. I will cut at the outside of the notches. This will leave a 1/16" notch at the ends for the tip ribs and form a 1/8" notch for the 1/8" center rib W-1. Once the ends are squared up, glue the spruce 1/8 "X 1/4" center brace on the 1/8" edge. The trailing edges of W-1 and W-2's are notched to go around this brace.

hfenn

When removing the ribs from the laser cut sheets, be sure to leave the tabs intact. Here I pushed all the rib trailing edges into their respective notches and made sure the tabs were snug against the shaped trailing edge stock. I was ready with my pins to pin this down to the building board, but they fit so well everything stayed in place with just a few light weights on the wing I didn't need to use pins! I got everything square and parallel and slid the 1/4" square spruce brace into the fronts of ribs W-1 and W-2. Next I tacked all joints with CA glue. Then I glued in the 3/8" dowel leading edge. Before gluing in the 1/4" square balsa spar, I rechecked the alignment on the assembly. It would be easier to correct now than after the spar is locked in.

hfenn

Next I glued in the top and bottom 1/4" balsa spars and the W-5 sub ribs.

hfenn

Next I glued the wing tips on the center of the outboard ribs and added the top and bottom tip braces. Ialso glued in some fill pieces from scrap balsa as shown on the plan on the tips. Then I sheeted the bottom center section with 1/16" balsa. The top will be sheeted after the bellcrank is installed. At this point we will begin to use some of the hardware, so a picture is worth a thousand words and I'm not that fond of typing!

hfenn

Assemble the bellcrank and leadout wires. Be sure to properly locate the bellcrank so it centers over the spar. Here I have everything in place but not glued yet. I slid the fuselage on and checked where the 90* bend on the pushrod needed to be for the elevator. Mine was slightly different from drawn probably due to dimensional changes in the paper (it's really humid here). This is something you want to get right since it is the heart of a control line model. Once satisfied, securely glue in place and sheet the top center section with 1/16" balsa sheet. I had to use a little spackle at the joint with the leading edge dowel. After making the pushrod, there is enough wire left to bend up a tailwheel wire.

hfenn

Next I slid the leadout guides over the wires and glued them in place. Then I crimped on the eyelets. I marked some lines offset from center on the wing to aid in alignment when it comes time to glue the wing in place.Here you see the tailwheel wire about to be glued into a hole I drilled and then in place with a little glass cloth for re-inforcement. Now I'm ready to cover. I'll post updates from here, but there will be more time between posts as I have to go to the lhs for yellow covering and order the Army stars (lhs doesn't have them). Also, in a week I'll be busy for about two weeks with work stuff out of town. This has been a fast build and I'm looking forward to flying it!

optech

My Feedback: (9)

Whats the wing area of this model?

Thanks,
Mike

skaliwag

My Feedback: (1)

254 sq/in. for the w/area. Should weigh in a round 20oz with OS .15

optech

My Feedback: (9)

Would an Enya .19VI be too much?

Mike

Kiwi

In my opinion, within certain practical limits, if you actually know what you are doing, you can accomodate a wider range of engines than a given kit was designed for. I would not suggest a Veco 19 as being appropriate for anyone who must ask the question, but I'm just not familiar with the power output of any Enya. I've had several pass through my hands, none of which had been fully broken in, and I never had that much patience, myself (I have another 29 once again, with an irron piston and steel cylinger that I haven't tried to run, to see if this time someone has had that level of doggedness, and yet still been willing to turn it loose).

The Enya 19 is bulkier and heavier than the "target" engine for the time frame when the Akromaster was designed (Fox 15X), so the nose would need enlarging / strengthening, and the tail would need lengthening. The only engine in the 19 / 20 displacement range that I'd suggest as entirely appropriate to a beginner would be the iron piston .20 from OSMax that predated the FP. It was their last loop- scavenged engine, and compared to the 19s that came before it, was very mild, even a little effete, perhaps, rather than being brawny. They were often referred to as "Max-S" 20s (incorrectly), because they were offered at the same time as the Max-S and Max-H engines were also on sale.

hfenn

Funny you should ask. During this build, I was motivated to build an Akromaster I've had under the bench for a couple of years. I put an Enya .19-V CL in the nose of this one. On the Sig kit, you get instructions on how to change the spacing to suit the larger engine. I put this as far back in the engine bay as it would go. I also had to cut out the left side cheek to accomodate the depth. I also then had to trim 3/8" off the nose to clear the drive washer. It balanced pretty close, just a tad nose heavy and that is using the muffler. I just came back from the first two flights on it. I wiped out a rear lg locating dowel at the bottom of an inside loop. The next flight was better (because I had the engine adjusted better) and I was able to complete some wingovers, horizontal eights, inside and outside loops. I feel I need a little more up elevator authority (the pushrod is already the closest hole to the elevator) so when I got home I added 1/4 oz. to the tail. I did find out that I don't need a 2 oz. tank! Ten minutes! Whew! That being said, on the Select Hobbies PT-19, the nose is 1" shorter than the Akromaster. So, although it worked ok on the Akro, I hesitate to say it would work on the PT-19. I have a plain bushing Fox .15 that is going on the front of the PT. I hope to be able to let you know how it flies soon. I got the covering for the wing today, but my decals will probably arrive after I have to leave for work next week. Perhaps I'll fly it before the final finishing touches. BTW, both the Akromasters I have now came out to 20 .oz. I'm looking for the PT-19 to be lighter because the wood provided is lighter than in the Sig kit.

hfenn

Back on topic, I covered the fuselage with blue Ultracote. Leave bare wood where the "flaps" will glue on.

hfenn

I made locating marks with pencil on the wing at the fuselage joint when I found the center and where it squared up to the fuselage. Then I slid it over and applied some 30 minute epoxy all around the wing between the marks. Then I slid the fuselage back between the marks and checked everything for proper alignment. Make sure the wing is square to the fuselage and aligned with the horizontal stabilizer before the epoxy sets.

hfenn

The last bit of wood work is to trim the ends of the "flaps" to match the contour on the plan and then glue them to the wing trailing edge, tip, and fuselage side. Hopefully I will get the wing and tail parts covered tonight.

Jim Thomerson

My weight goal for a 15 powered model of that size is 17 to 19 oz. I've built the same airplane at both weights and there was a clear difference in how much better the lighter airplane flew. You will probably have a pretty good airplane, but don't add any weight you don't really need.