BJ-J3 Cub - NOT a Failure Story - Plans and Build Instructions

[BanditJacksRC]

Bandit, As you begin to work on the plans. I thought the tail was gonna be to small. I would make it 15-20% larger. Also maybe the ailerons about 2'' longer down the wing. Also i went back and looked and forgot to add these pictures. I was laying in bed last night pondering on this and thought, maybe this big hole in the bottom of the fuse had something to do with it.

I thought maybe air was getting trapped in the big gapping hole of the fuse. Just a thought. Also Bandit this was a thought for next version of the plans, to instead of making the fuse fold on the left,right, and top. It should be left, right, bottom. I am sure in your computer you could add a couple small pieces to fold over and make the top. and use poster board in the remaining gaps.

I don't know if the hole makes a difference or not, but my plan from here is to make a larger tail, cover the hole in the bottom with some poster board.

Just got to work, so now the fun can start!

My plans for now:

As far as the tail size goes.. that is all def. getting enlarged, prob right around 15 to 20% like you suggested%.

For the wing, the overall chord I will make a bit wider (prob 1"-1.5" or so) and will lenghten the ailerons down the wing like you suggested. Also I want to keep the spar, but will shorten the height to the foil will not be nearly as tall.

I like the idea of bringing bringing the nose (and motor) a bit further forward to help with nose weight, and will be adding that in as well.

I also really like what you did with the tail servos and think I will do the same for this build.

As far as folding the top and sides, I was pretty much just replicating the idea from the storch. The fuse for that bird is a 2 peice that gets glued together, but for the front of the fuse the top and sides are folded together, and the aft section is added.
I can def. change that, but not sure how that will affect/fix the poor flight characteristics.

I don't think that hole would be a big issue, maybe adding some drag but don't think it has a lot to do with the turning issue. I'm not sure tho. I'm still pretty new to RC, especially to creating plans, lol.

These changes shoule hopefully help... we'll see I guess!

 

[mrstamp80]

Thanks for the reply. Can you give me a little more info on your bank and yank behavior? Maybe indicate a time stamp in your video and call out what your sticks were doing.

Sure a good point start the video at 4:43 as it is in level flight going toward the building. I was gonna bank and yank to the right (direction of plane) to avoid the building, and the tail drops out and it doesn't turn. I applied full throttle to get it to climb and avoid the building. You can hear me throttle up then i gave it full rudder and it dives.

 

[mrstamp80]

Alright got a new tail built! The old tail horizontal stabilizer measured 10 7/8 long, 4 3/4 wide. New measures 14 3/4 long, 6'' wide. The vertical stab old was 4 1/2 tall 5 3/4 wide, new is 7 1/2 tall, 7 1/2 wide. Here are some pictures,






I changed the design of the tail as well. i gave it a little bit of sharper angles rather than smooth curves. Now all i need is a decent day if the wind would just calm down a bit and I will try again. Also for nerdnic the AUW as it sits now with the new tail assy is 18 ounces. I will keep you posted.

 

[BanditJacksRC]

Very excited to see if this helps you. I have made the changes to the plans, but am unable to start the build for another week or so.

 

[Christopher14]

That new tail should help quite a bit.

 

[Cody]

I can't wait to see how this turns out. Definitely will build one if you are successful.

 

[Christopher14]

I'll probably build one to.

Welcome to the forum Cody!

 

[jh1985]

I would lovve a updated copy of the plans.

 

[BanditJacksRC]

I would lovve a updated copy of the plans.

Sure! I would be happy to send them to you. The only think is I am not sure how to PM a PDF. If you want to PM me your email I could send them to you asap.

I was a bit burnt out of this cub and took a bit of a break from it, but will be building with the updated plans during the new year break.

With the updated plans I have enlarged the horizontal and vertical stabilizers. (more so on the vertical) and made the wing spar a bit shorter. I added score lines on the wings for the foil. As well as tweaking a few things on the fuse that needed fixing.

 

[mrstamp80]

Also, just a update for you bandit, I have the modded out cub sitting here and waiting to go out. I have been off work from xmas to new years which is great! (my company shuts down that week) The only problem it's been that misty rain on and off everyday. urgghh!

 

[BanditJacksRC]

right on! yeah I have actually been getting a bit of rain here as well (Mesa, Arizona - if you can believe it!) lol. I have the next 4 day s off and will be getting back to work on this one in the morning! def. excited to get this one all worked out.

Be sure to let us know when you do the maiden on V.2. I am convinced it will fly even better.

 

[mrstamp80]

Finally, got a flight in with the new tail assy. It flew VERY VERY WELL. It was a much vast improvement. So, here is all my electronics and what not,
motor: turnigy dst1200 (57gram)
esc: HK ss 18amp
prop: gemfan 8x4.5 slofly
servos: 4 9gram
RX: power-up rd610 dsmx
Batt: Turnigy 1300mah 3s 25c
The AUW came in at 18.8 ounces. Motor should make about 25oz thrust @wot, and draw 16amps. It seemed to be a good combo, as it would cruise at 2/3 throttle mostly.

So here is a picture of my batt placement, velcroed to the bottom of the power pod.


Now here is the flight video of it with the new tail..

So here is a picture of my batt placement. Which is about

 

[Christopher14]

Very nice!

 

[nerdnic]

Woo!

 

[mrstamp80]

The crazy part is, i reset and centered all the trims. I never once trimmed it out, but in her defense it was really gusty above the tree line and this was more of a "will it fly and turn" kind of flight.
You still need to feed a little rudder in it for scale wide turns. Overall a few more like tweaks and bandit will have a nice airframe.

 

[desert wings]

Great job.

 

[BanditJacksRC]

oh man right on! this is great. I didn't get much building done over ther break. I finished up the nnMIG3 but the family was sick and didn't have much time with the exacto.
This is def. some major insentive to get back to this build tho.

 

[jh1985]

Ok you said you didnt know how to post the plans so here ya go. It will be easier for others to try your design out too. Thankyou.

 

[jh1985]

im working on a 70% version

 

[BanditJacksRC]

oh nice thanks man. A 70% huh? That will be interesting!
I made a larger cub before but not from any plans, just drew it out from a 3 view and went with a 50 in wingspan.

I made this one pretty small in comparison and a 70% would be great to see.

Best of luck!