Scale Build Off - 1/4 scale (55") Pitts Challenger III

[wilmracer]

Working away on this one and it's helping keep my mind off the other one that sits needing a rebuild

But I've got the top wing well under way. Servo mounts and servos installed, hatches installed, CF tow laid up, and the interwing struts have been cut. The plans for the Challenger II have them parallel (perpendicular to the wing) but they should be canted out, so I've modded the mounts to make them that way. Should look a bit more scale.

Still plenty to do but a few more days at this pace and I'll have the wing and upper ailerons ready for glass. I'm going to get this one into primer, tape the canopy on, and put some tape on to help with orientation and will be doing the maiden before final paint. I may leave out a few other touches before getting the maiden in, just to have time to get her airworthy before FF.

 

[wilmracer]

This just came up on my youtube feed. A bit of motivation

 

[Crash and Burn RC]

When do we know who won?

 

[wilmracer]

When do we know who won?

Results are already in Click Here

 

[wilmracer]

Been a while since I posted an update but work has been continuing. Top wing is getting close to glassing. Just need to balsa line the leading edges, install the pushrod exits, fill, and of course sand. Oh... also need to add the flying wire mounts.

Last night I got the upper wing fully mounted. The interwing struts will be balsa sheeted and glassed and that will clean up the look a bit more. They are held in place with a pair of 4-40 bolts on each wing tab and feel quite solid.

The mount at the cabanes was interesting. I used a pair of 1/4 nylon wing bolt retainers , drilled them out, added a "bushing" of CF tube that exactly fit the 1/8" music wire, and then installed them on the mount. There is a long section of 1/8 music wire with an L bend in one end that is inserted from the front and will be held on in the back with a wheel collar. The whole thing will be hidden within a fairing but I probably wont bother with that fairing until after the maiden.

Hoping I can have her airworthy by weekend after next. Want to get the maiden in so i can shoot some paint. I probably won't be bothering with the full cockpit/pilot setup before FF but if she's flying that is the important thing.

 

[wilmracer]

Pushing hard this weekend.

Glass is done and curing. Hope to sand and prime wings and control surfaces tomorrow.
Tailplane struts fabricated and installed. Happy with how they came out... wish they were a bit lighter, but they are strong and will hold up great.

Also did a test pitch of the new tent for Flite Fest. It will be fantastic to not be in a 2 person backpacking tent this year

 

[willsonman]

Looks awesome, Carl! I think the tail struts look a bit too thick for scale but that is my TLAR approach right now. May want to check your references. At the very least you could use a hammer and anvil to flatted them a bit. Maybe I'm the only one who looks at details like airfoiled struts but it is a consideration.

 

[wilmracer]

Looks awesome, Carl! I think the tail struts look a bit too thick for scale but that is my TLAR approach right now. May want to check your references. At the very least you could use a hammer and anvil to flatted them a bit. Maybe I'm the only one who looks at details like airfoiled struts but it is a consideration.

You're not wrong, They are a bit to thick for scale (and to be honest don't attach at 100% scale locations). I didn't have music wire that was just right so I went with this to get it done. I may go back and redo them, or give your hammering idea a shot, but for now they will do.

There will be a lot of scale details that I wanted that probably won't be done by FF, but if I can get her flyable and presentable I can go back and add some later. The cockpit will probably wait until after FF... I've still got others in the fleet to tune up and just over 3 weeks to do it

 

[wilmracer]

Still grinding. Wheel pants are on. Legs will probably need some tweaking to look just right, but for the now it will do. When I get the back sides of the axles cleaned up and painted I think it will look good. I had gone ahead and thrown some paint on the pants... not 100% sure that will be the final red I go with but I want to see it out at the field.

 

[wilmracer]

So... The more we build the more we learn. Sometimes we learn the hard way. I thought I had come up with a clever way to capture a relatively minor detail on this airframe... the subtle scalloping between the wing ribs. I figured I've give this a shot even though I hadn't seen it done this way before. Lessons learned:

• If you're going to use a "new" way of building a wing, do it on a MONOPLANE!
• Buy stock in 3M and Krylon, cause you're going to go through a TON of primer and sandpaper

Had these wings been standard glass over foam, or sheeted foam core and glassed, she would be airworthy right now. But with the semi-sheeting and filling method I tested on this build I have had a TON of surface work to do. In total I spent more than 12 hours sanding this weekend. And I'm NOT DONE YET

I think the finished product will look good, and I'll write off any imperfections that remain as "wrinkles in the fabric", but IMO this method wasn't worth the time and effort. I got a bit of primer shot on the ailerons for the upper wing but have only just started them.

I think I will still be able to have her airworthy by next weekend and I'm targeting Saturday for a maiden in primer. Assuming it goes well I'll pull her apart and and get her finished enough for FF. Fortunately I think the Red paint will go on quickly once the surfaces are good.

 

[saiga556]

Those weekends when all you really do is sand stuff.... seen a few of those.

 

[willsonman]

I think that the end product here looks phenomenal! This is exactly what I envisioned when we discussed this months ago. Its not over the top but prevalent enough that you can notice, even at a distance.

Just a side note of caution. Keep her out of the sun unless flying. Any degassing of the foam causing bubbles will ruin the effect. I've invested in a camo net for this. She needs lots of shade!

 

[willsonman]

So, I just checked the forecast for this weekend and things look good for the area on both days! I really look forward to hearing a positive update on this one.

 

[saiga556]

Maiden this weekend? It's about time. I expect to see some hardcore pattern flying it not some full 3D.

 

[kerrycorcoran]

Wow! I wish I had this type of talent! Very cool!

 

[wilmracer]

Maiden this weekend? It's about time. I expect to see some hardcore pattern flying it not some full 3D.

Lol... not on the maiden you won't

3D will also be out... she has a bit more weight on her than I wanted. TBH the wings came out heavier than I anticipated. Live and learn. She is still very reasonable in terms of wing loading and cube loading but the power system won't provide the >1:1 thrust needed for 3D. Honestly it wouldn't matter if it did... I'm no 3D pilot. If I can fly her scale I'll be happy.

 

[wilmracer]

 

[wilmracer]

Maiden video! @ 4:20 my wife asks the big question... will it be ready for Flite Fest

 

[AkimboGlueGuns]

It's so beautiful! I can't wait to see her in person. Also, good luck with the (re)maiden! I hope you're able to get it ready before FF.

Also, nice job saving that thing! That was wickedly tail heavy, and especially on a bipe that had to be ridiculously touchy.

 

[HilldaFlyer]

Terrific job on the recovery! My first maiden with a tail-heavy plane was not so successful. See you at FF2016.