18" Wingspan Mini Sportster

[kacknor]

Just and idea... Pretty much. So far. How about a slower flying 80% scale Mini Sportster? This came about after flying a Mini indoors. Got 2 acres under a dome and I find I've got room to fly, but not enough room to play. Skills not there yet I guess. So..

I reduced the plans. Lightened the wings by removing foam and paper from inside the fold. Removed all the paper inside the fuse and assembled the first proto adjusting plans as needed.

What is shown below is already superseded. Wing would still be too fast. I added more thickness, but took off too much foam and it affected the airfoil. I removed the paper from the underside of the elevator and it warped in minutes. Oh well.

Ver 2 is as far along now. Added undercamber to the wing. Left paper on elevator. Took off paper inside wing, but no foam cuts. All paper off inside fuse. Tomorrow I'll figure out the pod and add electronics.




Hopefully I'll have a weather break chance to try it and see how (if?) if flies. I'll be using 4.7 gram servos, a 6 channel Lemon and a 17 gram Hex 1700 KV motor. Should it do OK, final will use micro servos from HK 1.7 gram.

JD

 

[xMeox]

awesome! can you upload a picture of the underside of the wing?

 

[kacknor]

I can do that... This is first effort that didn't fly.


Bottom side. I used double layer of foam strut to get a fatter airfoil. All I did was deform the wing were I took out too much material.


Warpage. I don't recommend taking off only half the paper if there isn't any hot glue support going on.



JD

 

[kacknor]

OTOH... This one flew today. I failed miserably to get a docile slow flyer, but this isn't bad. Not slow, but no racer either. Tracked well, and roll rates very good considering I was running 50/50 on the DR&Expo for ailerons.

Going to have to take my word for now. My brand new Mobius is smarter than me. I thought I was turning on, it paused. Pictures may show results of the nose plant on my first launch, skewer holes suffered. Battery was a good wedge for a flight in just after.




The 5 gram motor wasn't going to cut it here, I subbed in a 200 Quad 3000kv. I used 5 gram servos, and the smallest 2 cell battery I had was a 500. So I'm liking this one for a third try. 17 gram 1400kv Hex, 1.7 gram servos and a 300mah 3 or three cell battery. Will have to adjust fuse width a tad also. Power pod isn't standard. Had to shave a 1/8" off the firewall.

So, back to the drawing board for the desired slow flyer.. May (nearly) have to go with a profile fuse and a single piece wing like the Mini-Scout.

JD

 

[xMeox]

nice work! the second wing looks much stronger than the first one, maybe strong enough to remove the inner paper after all

 

[kacknor]

The inner paper is gone on both wings, and fuse. Plenty of strength for both. I have 300 mAh batteries on the way, as well as 1.7 gram servo's. The next build will use them. I also have a nnManicMicro toger Moth in the works.

http://flitetest.com/articles/manic-micro-nntiger-moth-build

I may have to stay with the Quad motor as the sacrificial Baby Baron that was going to provide the 17 gram got a far too much than practical amount of hot glue and will fly again.

JD

 

[xMeox]

looking forward to read about the final version. I decided that I will not get into the micro plane thingy, at least for now. I have bought a lot stuff for FT swappables, which I now dont use because I only build mighty minis atm. If I now get micro gear as well I would have even more unused stuff. Maybe someday when my swappable projects are finished

 

[kacknor]

looking forward to read about the final version. I decided that I will not get into the micro plane thingy, at least for now. I have bought a lot stuff for FT swappables, which I now dont use because I only build mighty minis atm. If I now get micro gear as well I would have even more unused stuff. Maybe someday when my swappable projects are finished

Finished? What? I have no idea what that may mean...

My Storch is in need of attention, as does the Bushwacker. The plans I printed for the Spitfire are taped and rolled, waiting on a more opportune time. I have servos and motors and a coupla 30 amp ESCs. Just waiting on the warm Spring to get here...

That's when the minis and miro's will hang, loney on the wall, awaiting their indoor moment once again.

JD

 

[kacknor]

So I wanted to make a mini-Mini. Goal was slow and easy, with a 5 gram motor. Didn't quite get there, but it used a 200 quad motor and was slower, and flies much like the mini. Made a second effort today. Glides nice, but needs plans adjusting. Had to tweak quite a bit during assembly. Tomorrow.

Lower is a Mini. Middle is 18" wingspan and 14.5" long. Top is today's fun and came in at 14" wingspan and 11" long. I think this one may get by on that 5 gram.



JD

 

[kacknor]

14" ready to maiden. All that's need is a calm(ish) day and batteries that will fit. The batteries will be easier I think. My smallest 2 cells are 500 mAh, a tad too big for this. I'm thnking 200 or 300 mAh is needed.

I did plug in an 800 for testing. With a 5x4 prop it drew 1.7 amp flat out. There was probably enough thrust to fly it, but not enough to be 100% sure. With a 6x4 it was 2.3 amp, but the trust was definitely enough to do the job. The 5 gram motor is rated for 2 amp, and got warm. Going to pick up a 6.3 and see if there is a happy compromise.

 

[kacknor]

So, a sad update. Tried to fly the 14" Micro Mini and no go. Had plenty of power but torque was a real issue. For about 6 seconds as it rolled inverted and flipped upright to a short hover I REALLY looked very cool and as if I knew what I was doing. Then the moment passed and it nose planted.

Subsequent attempts showed lack of control surface authority flight attempts were short and generally ugly.

Going to get back to the 18" version and play a bit more. Potential there as it flies pretty well but required further tweaking.

Side note, I also tried a 16" J3 Cub scaled down from a 40" version. That may just go if I can get the expo dialed in to something matching my pilot skills.

JD

 

[The-One-Who-Never-Crashes]

View attachment 60317 View attachment 60318

JD

Ha, ha, ha!

 

[kacknor]

You know, I think I actually told the guy flying next to me to "Hey, watch this..."

JD