Hello all. I've decided to build the Dynaflite Super Decathlon for a winter project. I was trying to choose between this bird, the Sig 1/4 scale Spacewalker and the Sig 1/4 scale Cub. The Decathlon seemed to suit what I wanted the most, so here we go. I thought it would be fun to do a build thread on it since I've never done that before and I really enjoy the process of taking a stack of sticks and turning into something that flies! I'll probably be powering it with a Zenoah G-38 as that seems to be the popular choice. Coming from a glider background, I'm a bit of a weight weenie and don't really like the weight of the Zenoahs but it seems that you need lots of weight in the nose to balance the Decathlon anyways. I'm also semi-interested in weed eater/ chain saw conversions and would appreciate anyone's opinion on that! Here's an interesting page I found that has some really cheap stuff!

http://www.carrprecision.com/Pages/prod02.htm

Anyhow, here's the start of the progress.

It's a really big box. I was actually surprised when I opened it that there wasn't more stuff in it. Then I took everything out and couldn't fit it back in.... so maybe it was pretty well filled.

Here is the building board prepped with a piece of dry wall and some wax paper over the plans.

And all items properly inspected.

The vertical stab and rudder flew together pretty quick. Be sure to read the note when sanding the LE, don't sand the part where the fin meets at the bottom. Oops.

The horizontal stab goes together quick but the elevator takes a little more prep work. You have to laminate 5 layers of 1/16" balsa together to make the curved edges. I used alphatic resin instead of CA. It takes a lot of T-pins and patience but the end result is really nice and light. Here's the elevator prior to laminating.

Here's the laminating process shown with lots of T-pins to hold either side of the edge in place and all squished together.

All done! The wood quality has been pretty good but a little on the heavy side. Be careful to hang on to scraps because they don't give you much extra wood in this one! Now on to the wings. Total build time so far, about 6 hours.

Wow, are you planning on having this thing done by the week end.
Looks real nice, I've always liked the Decathalon

I built one last winter, loved the build. I met a couple people using the G38, however I used a Super Tigre 3000 and inverted pitts muffler. I mounted the tank all the way back, over the main gear with one receiver battery towards the firewall, balanced perfectly, flys great, two click of down on maiden that was it.

Wow, that's a nice looking airplane. Did you put the servos in the tail like on the plans? What was your finished weight? Thanks!

There is one servo for rudder, 2 for elevator's, all are located where the plans specify. One thing I did was up in the front, instead of permenantly attaching the forward deck (where the canopy glues to) I converted it into a hatch, in case I ever needed to get in there, I also added bracing around the landing gear plate, these have a tendency to be extremly weak. I also got the fiberglass cowl and pants from fiberglass specialities, tried the abs cowl that was supplied but man that would have been alot of work. Good flying plane.....

Very impressive. I'm getting ready to start mine this week depending when it gets here. Not Dynaflite, but sureflite 96".

Here are some more pictures. I have one wing panel mostly built, minus some final sanding and servo mounting. The die-cutting has been great. The wood is still a little on the heavy side, especially the ribs. The instruction manual could use a little tweaking. Be sure to read every item word for word and inside out or you will miss something. So far I'm pretty happy with how its going and can't wait to get started on the fuselage. (too bad I have to build the other wing panel first!)


Ribs and main spars in.

I wanted to build both panels at the same time. Unfortunately, they only provided one balsa piece to create the washout in the wing. Instead of going to the store and buying more balsa, I am building one at a time!

Spars and shear webs in. This thing is beefy!

Does anyone have pictures of how they mounted a G-38 on the firewall?

All sheeted and done, looking good!

Tadaaa! Total build time to this point, about 17 hours.

Lookin good

Awesome! What servos do you plan to use?

I haven't decided just yet. They will probably be standard sized high torque ball bearing servos. I'm shooting for 70-80oz of torque. The rudder may be metal geared and the throttle will probably be something lighter. More pictures are coming soon. I've built the 2nd wing panel and have been sanding away at the leading edges and wing tips.

Looking good.

I have Hitech 475HB servos for elevator (2) and one Futaba 3005 for rudder in the stock location. I use my Decathlon for aerotowing and she handles 15# sailplanes with ease. Mine is "E" powered with an AXI 5330/18.
It flies like a *****cat when not towing and slows down great for landings.
Probably the only down side to the kit is the soft landing gear, mine will bend if not greased in. I plan on beefing it up for next springs aerotowing season.

cooper998

The aero-towing stuff really excites me. How and where do you hook the line to on yours? I plan on beefing up the gear a little using a piano wire support that someone else showed on here. You have a nice looking plane!

If you look closely at the second picture of my plane you can see the tow release just behind the trailing edge of the wing. I machined my own from aluminum (it pays to have a lathe and mill in the shop) roughly similar to a commercial unit made by Ben Diss. The best place to tow from is the top of the plane, unlike full scale that uses the tail wheel attachment.

If I get around to it this weekend I will pull it down from storage and take a couple of pics of the setup,

cooper998

I would be very interested to see that. Did you beef up the fuselage where it attaches? What kind of line do you use? Thanks!

Update! The 2nd wing panel is done and so are the ailerons. Most everything went well with these except for some mishandling/hangar rash at the fault of me. The wing tips and leading edge took a loooooooooooooong time to carve out. This is also the first time I've ever cut a wing tip outline with a table saw! Using a 1" drill bit I drilled out the inside of the wing tips to save some weight. I think it ended up saving 2-3 ounces, which isn't much but I can't stand dead weight. I did have to buy some balsa for the ailerons that was not included in the kit, no biggie though. I also messed up on the ailerons and put the light ply control horn reinforcement on the wrong side. I'll probably just leave it as is since the control horns attach from both sides and there is solid balsa all the way through. It saves to read very carefully in the instructions, hopefully you all do a better job at that than me!

Here are the wing tips shaped and drilled.