Shop our Airplanes Products Drone Products Sales
Thread Tools
Aug 27, 2015, 06:59 AM
Registered User
Discussion

Box/Joined Wing


This one was a complex build (at least for me ).
I found the whole concept of a rearward swept front wing joined to forward swept rear wing to be intriguing. The Elytron was my inspiration for this one, but mine can't do VTOL and it has no wing taper (just sweep). I wanted a single motor, so I made the struts around it to join the two wings.
No camera man available, so the flight video has some gaps.
I hope my neighbor can film it soon, so I can update this thread with a better flight video.

Specs:
Front wing span: 51 in.
Front wing chord: 8.5 in.
Front wing sweep: 30 deg. (rearward swept)
Rear wing span: 57 in.
Rear wing chord: 12 in.
Rear wing sweep: -15 deg. (forward swept)
Vertical height between the wings: 13 in.
AUW: 49.5 oz.
Wing loading: 6 oz per sq ft
Wing cores: Medium bead styrofoam, cut with hot wire, CF tube spars, MH60 airfoil
Motor: Turnigy D2836/8 (1100 kV)
Prop: 10 x 4.5 "slow fly"
Battery: 2200 mAh, 3 cell, 25C

Best viewing will be achieved if you watch this video in its entirety, in full screen mode, on a computer monitor:

BoxWing loops and rolls (6 min 1 sec)


Runway take-offs/landings:

BoxWing Runway Takeoffs and Landings (1 min 17 sec)


Discussion:

Tips for BoxWing (10 min 43 sec)


Tips for BoxWing Landing Gear (3 min 16 sec)
Last edited by nuteman; Sep 20, 2015 at 04:16 AM.
Sign up now
to remove ads between posts
Aug 27, 2015, 07:38 AM
Careful,.. confident,.. CRASH!
Dukejet's Avatar
Cool! Nuteman that's unreal! Should fly well. Will be waiting for the video .... or it didn't happen
Aug 27, 2015, 07:58 AM
Registered User
Quote:
Originally Posted by Dukejet
Cool! Nuteman that's unreal! Should fly well. Will be waiting for the video .... or it didn't happen
Thanks.
The first video is a very short video of the launch and landing (I had the camera on the ground).
Aug 27, 2015, 08:28 AM
Tony Audsley Retired Locksmith
Lockey's Avatar
Now that one is a bit different mate, nice one nuteman

Lockey
Aug 27, 2015, 08:31 AM
Registered User
Quote:
Originally Posted by Lockey
Now that one is a bit different mate, nice one nuteman

Lockey
Thanks, Lockey.
Yeah, that's why I built it. Doing a layout I've never done before is always a fun challenge.
Aug 27, 2015, 09:18 AM
who has rabbit ears down
Captain Canardly's Avatar
Great ob Nuteman! now we'll clean it up a tad!
Latest blog entry: Let the Competition Begin!
Aug 27, 2015, 10:10 AM
Registered User
Quote:
Originally Posted by Captain Canardly
Great ob Nuteman! now we'll clean it up a tad!
Thanks!
Yeah, it would be prettier if I enclosed all the electronics and wires on the motor pylon. The only problem is that adds weight and it's pretty much at the max weight for a hand launch with that motor/prop. I guess if I end up flying it a lot I can get a stronger motor and matching ESC. I could've made a smaller version of it and done it prettier, but larger scale just flies so much better, so I maxed the scale to match the CF tubes I had
Aug 27, 2015, 11:40 AM
Registered User
jumo004's Avatar
Very cool !

Here's a kit of a similar plane.

https://www.rcgroups.com/forums/show....php?t=1277270
Aug 27, 2015, 01:11 PM
Registered User
Quote:
Originally Posted by jumo004
Very cool !

Here's a kit of a similar plane.

https://www.rcgroups.com/forums/show....php?t=1277270
Thanks.
Yeah, that Stratos is a lot "slicker" than my home-brewed design
Aug 27, 2015, 02:18 PM
I Look, Listen, and Learn
Timbo383's Avatar
Love it, with your permission I would like to try to copy it.
Aug 27, 2015, 05:14 PM
Registered User
Quote:
Originally Posted by Timbo383
Love it, with your permission I would like to try to copy it.
Thanks.
Yes, by all means - copy it, improve it, etc.
I found the biggest challenges were:
1. Making the struts/cage/motor-pylon precise enough and strong enough, yet still have a tiny bit of "give" at the joints. You can not simply glue the vertices of the tetrahedron - not strong enough. So I ended up drilling precise holes in the ends of the dowels and joining them together with very thick wire.
2. Anchoring the wings to the cage - you must have solid/precise anchoring to the wing spars themselves. Any other place is likely to rip out. Example: The forward wing's two spars are joined at the center with a bent iron rod inside - providing the anchor location for that point. The bar of the A-frame on the front wing is the second anchor location for that wing.
3. Keeping the wing loading down while keeping the wings rigid. This is a lot harder than it sounds and becomes more challenging as the scale goes down. I don't think, for example, that I could've managed this plane at half the size.
Aug 28, 2015, 08:02 AM
I Look, Listen, and Learn
Timbo383's Avatar
Not sure about improving it, usually my changes make it worse .....I do want to clean it up tho, I know you're more into can I get it to fly and when it does, just enjoy it. I have lots of cf rods so the weight will be down and I'll be using DTF, so it should be a quick and easy build since you already did all the hard work.
Aug 28, 2015, 08:16 AM
Registered User
Quote:
Originally Posted by Timbo383
Not sure about improving it, usually my changes make it worse .....I do want to clean it up tho, I know you're more into can I get it to fly and when it does, just enjoy it. I have lots of cf rods so the weight will be down and I'll be using DTF, so it should be a quick and easy build since you already did all the hard work.
Even though the design is complete, it will definitely be more time consuming than a typical build - but, yes, you have the benefit of not having to make the mistakes I did at first

By the way, for mine the CG needs to be at 14.2 inches back from the tip of the front wing.

The paper on DTF is half the weight, so if you're using CF tubes in all the right places:
I suggest removing all of the paper and covering the outer surfaces in light packing tape - you have to cover with something even with paper on, as moisture eventually causes the paper to peel/deteriorate. The exception would be the control surfaces, which should flex as little as possible - so leave the paper on and cover in tape for those.

Anyway, good luck and be sure to share your version with us
Last edited by nuteman; Aug 28, 2015 at 08:35 AM.
Aug 30, 2015, 12:37 PM
I Look, Listen, and Learn
Timbo383's Avatar
Got started yesterday. Making half the size and going use kf strips to stiffen and cover the cf rods. Had some ideas for the motor cage, but could not get it work out like I visioned in my head so had to change that. Pin it together to test fit and still like it but now having problems with the cg....guessing 7-7 1/2 inches ...don't want to add a lot of weight to the front, so thinking about making it a tractor instead of pusher.
It's starting to stray from your design will post pics when it starts to go together.
Aug 30, 2015, 03:37 PM
Registered User
Quote:
Originally Posted by Timbo383
Got started yesterday. Making half the size and going use kf strips to stiffen and cover the cf rods. Had some ideas for the motor cage, but could not get it work out like I visioned in my head so had to change that. Pin it together to test fit and still like it but now having problems with the cg....guessing 7-7 1/2 inches ...don't want to add a lot of weight to the front, so thinking about making it a tractor instead of pusher.
It's starting to stray from your design will post pics when it starts to go together.
Tractor should be fine. Just make sure that the thrust line passes through the vertical CG (or very nearly so). Mounting it slightly aft of the nose will protect it somewhat in the case of a crash (and your first couple of launches or glide tests will probably result in at least mild crashes till you get CG and trim worked out).
Regardless, finding a reasonably rigid-yet-light way to anchor the wings to each other is critical - you don't want them moving around relative to each other (in any of the three axes) under flight loads.
You're brave doing it at half the scale I did - getting the wing loading low enough will be challenging (as I mentioned above), but I suppose it is achievable.
Curious what yours is shaping up to look like


Quick Reply
Message:

Thread Tools