WIP: Swappable Piper PA-12 Super Cruiser

[thatjoshguy]

NewZee, the ring connectors are genius. Just a perfect solution, really!

So that's nearly it for the build! Center of Gravity is a lot better now, and should be manageable by moving the battery if needed. Should have the new motor by Tuesday, but I'm going to try both if the new one works well. I'm curious to see how the 24gr HexTronic does.

I really need to nail the landing gear though. I tried something earlier using water bottle caps and those foam tubes you use in the swimming pool, but they were too wobbly and the plane would tip over when taxing. I'm using marker flags for piano wire so they're pretty strong, but not steady enough. I have another idea to try, just need the time to do it.

 

[NewZee]

Thatjoshguy........The ring connectors on my cub worked OK but I found I didn't really need them, I built the wing just like the FT spitfire, and I found it was plenty strong enough without additional support, They do look good, but are a PITA in taking the wing on and off to access the battery etc. of course I'm not doing high G maneuvers with it!

 

[thatjoshguy]

Thatjoshguy........The ring connectors on my cub worked OK but I found I didn't really need them, I built the wing just like the FT spitfire, and I found it was plenty strong enough without additional support, They do look good, but are a PITA in taking the wing on and off to access the battery etc. of course I'm not doing high G maneuvers with it!

Yes, its a great way to achieve the look while keeping the wing removable. Style and function. The battery is accessible without removing the wing on my model. The only time it needs removed is when making the connections, and even that can be avoided (for the most part) using servo wire extensions. The power pod fit is a little tight as I mentioned before, so as it is now it helps to install it without the wing so you can reach through the top when aligning it. I may scale it up a bit just to make it easier, but as it is now it's not too much of a pain.

 

[thatjoshguy]

Forgot I had taken these photos of the two problems I've run into so far:

Forgot to add a hole for the servo wires - easy enough fix. This is in the larger spacer in the fuse:



Even though things look right in SketchUp, I either had some scaling issues on my printout or cut this wrong. Note sure what happened exactly, but it was also an easy fix:


Rear poster board template is fine, though you may need to trim some for where you put the rods in to hold the wing.


I have yet to add the poster board on the nose on my build, as the template is apparently too small. It fits, but there's hardly any curve to it so it's useless. I was about to wing it and then though about adding a duct for cooling in the nose. Then I started thinking about air flow...

Question for the experts: The back of the plane is entirely enclosed, but the front has the open space for the battery placement... will this be an issue? Should I open up the back along the bottom so what wind goes in the front can exit out the rear? I'm afraid right now all the wind rushing in the front is going to swirl around and exit out the top where the wing is attached, pushing it up and away from the body (then again, I know nothing about the behavior of air.)

 

[NewZee]

I used a piece of BBQ skewer with a rubber band to secure the upper wing supports. the connection at the bottom is a piece of aluminum that goes all the way thru the fuse and out the other side for the other support.

 

[thatjoshguy]

I ended up gluing ring connectors into the wings, and for the bottom of the fuse it's a small skewer with connectors glued at both ends (for strength). Small twist-ties hold the ring connectors together in the prototype and seem to work fine, plus they're readily available - which is a theme I'm trying to stick with. What was it you used for your landing gear again? Is that sheet metal? I'm just not happy with any of my attempts at using wire...

 

[thatjoshguy]

Parts are here!!!


Now that is a better looking motor (on the right, obviously)! Bye Bye prop saver!


Plenty of room for a 3s 2200mAh battery (slid as far back as I could in this photo, it's nearly at the rear of the power pod)


And here she stands... Just need to add the connectors tn the ESC and wire it in the power pod!


I tossed a 9x5 prop on there, but it was too small for the prop adapter so I had to widen the hole a bit. I got a 10x3.8 slow fly which will work on this motor for a lot of thrust, but it's not as efficient. Ed @ Experiemental Airlines is the guy who collected data on this motor here:

Fingers crossed for a clear day!

 

[NewZee]

my Cub landing gear was fashioned from a piece of aluminum stock 1" X 9" X 1/16" looks like you are ready to take to the air! Good luck.

 

[thatjoshguy]

Soooo close... I got some stronger piano wore for the landing gear and some decent wheels (as seen in the photo above), but I need a stronger rubber band so it's not quite so bouncy. May just double up for now. It's beautiful outside right now, but I won't have time to charge the batteries before dark so Tue maiden take two will have to wait!

 

[SteevyT]

Have you tried coat hanger wire landing gear?

 

[thatjoshguy]

Have you tried coat hanger wire landing gear?

No - that might not be a bad idea, except I really wanted to use proper wheels this time around and I already had to widen the hole for this wire. Can't remember the gauge at the moment, but it was the next size up from what FT ships with their kits I think.

 

[SteevyT]

No - that might not be a bad idea, except I really wanted to use proper wheels this time around and I already had to widen the hole for this wire. Can't remember the gauge at the moment, but it was the next size up from what FT ships with their kits I think.

Coat hanger wire fits slightly snugly in a coffee stirrer.

 

[thatjoshguy]

Still waiting for the weather to improve so I can get this bird in the sky... shouldn't be too long I hope!

 

[thatjoshguy]

Very little wind today, took V2 out for her maiden. CG seems to be good now, battery is back under the wing so the front lines up almost. I left her a little nose heavy. Ran into a few issues I need help with, luckily I got it on video

Something is causing that yaw/roll. The first launch by hand may have been my rudder trim, but it looked straight before the crash so it may have just knocked it up a bit when it hit the ground.

On the second take off (from the ground this time) I had the same issue, but the other direction before ending my day with a wall. No major damage though, I should be able to get her back in the air soon enough. I don't think it's a design problem at this point, probably just a build problem. A better pilot probably could have handled it better.

I'm thinking maybe the wing isn't secured well enough, so it's coming loose and shifting. Perhaps I need a stronger rubber band or something. May just glue it down as I had originally planned.

Any ideas?

 

[Jaxx]

Josh,
You should definitely add more rubber bands The wing is way too loose, so the plane may not be functioning as a single airframe. The hand-launch looked a little pitchy, so it may have been a bit tail-heavy. Otherwise, the ground take-off looked really good to me. I believe it might primarily be a trim issue. I don't think it will take much to sort this out.

 

[Freaky_1]

Wondering about a little wing yawing on mout in flight myself.
Also, my eyes are not the best and I'm on a tablet, but is there some twist in your rudder top to bottom?

You might also flying without the struts to get her lined out, then work them back in??

No doubt you're close though!

Frank

 

[thatjoshguy]

Josh,
You should definitely add more rubber bands The wing is way too loose, so the plane may not be functioning as a single airframe. The hand-lauch looked a little pitchy, so it may have been a bit tail-heavy. Otherwise, the ground take-off looked really good to me. I believe it might primarily be a trim issue. I don't think it will take much to sort this out.

The pitchy hand launch was my fault, got a little excited and didn't realize I had full rates on the elevator. I'm still pretty green as far as my piloting skills go I'm going to get it reassembled and secure the wing better, then give it another shot this week if the weather turns out.

 

[Jaxx]

The pitchy hand launch was my fault, got a little excited and didn't realize I had full rates on the elevator. I'm still pretty green as far as my piloting skills go I'm going to get it reassembled and secure the wing better, then give it another shot this week if the weather turns out.

I think you will see much better results once the wing is secured.

 

[Michael9865]

Looks like you are close. Keep working at it.

 

[augernaught]

1 > It's tail heavy. Forward your CG.
2 > More bands, two like yours, and two crossed over the wings in an "X"
(#64 bands, and use alignment slats, wing to fuselage)
3 > Go back and read your entire thread again. Many of your solutions are there already, like your landing gear issues.

No offence, my brother! But it seems to me like you asked for help about many/certain issues,
and didn't incorporate any of the advice you were given?