Al Bowers gave me new airfoils, a detailed list of the twist and his proposal for the elevons.
I was really intending to go straight ahead for a full scale glider. I had a expert in Horten design for the wing design, i had a expert in composites to make the moulds and glider parts. What could go wrong??? Well, luckily the composite expert, Kees Radius, told me it would be best to test it in a large scale model. That proposal probably saved my life as i intended to be the testpilot.
DOWNLOAD WING DATA
On this page you find the data which you need to remake the DragonWing as i would do it now.
Difference with the way we started the RC-model is the type of elevon (started like Reimar Horten drew on his HXc-plan) and the dihedral (also like on the HXc-plan). Dihedral i used in the beginning was 5°. After crash number .. we changed that to 2°. Problem was solved that way. Bill Moyes was surprised to hear we solved his adverse yaw problem, which he encountered with his HXC variant.
Link to excell file is at bottom of page.
Test flights
Note about the testflights: my dutch team members had their own thinking about CG placement from their RC experience. Sometimes crashes happened due to bad CG. I was happy to hear them say in one of the videos that the glider was best with the CG ...where Al Bowers told them it should be. :)
Also we tested several types of elevons. Elevons with 1/4 chord, with 1/3 chord, elevons with a full part of the wingtip attached, triangular elevons. We also tested dragrudders. Last was done just to see the difference with the normal elevons.
You can see a overview of proposed elevons by Edward Uden in this document by Albion Bowers: http://www.nurflugel.com/Nurflugel/Papers/Al_Bowers_Horten_X_Series/bowers_2_7/bowers_2_7.html
We tested proposals 2, 3, 7 and 10.
Day 1
We made our first testmodel. Night was nearly falling, but we wanted to try it just before sunset.
You can see our first crash at 1:00.
At the end we nearly hit a wall at the end of the field because we underestimated the glide ratio of the model. The model didn't sink! We need airbrakes!
By the way ...my first name, Koen, is pronounced as racoon without ra. Not KO-EN. ;)
Day 2
After those flights we installed airbrakes for better glide ratio control when landing. Also we installed dragrudders at the inside of the elevons. The dragrudders were only done to see the difference between usual elevons and dragrudders.
Day 3 and 4
The third test flight video received the name "From Disaster to success". Well, here you see a list of what is visible on the video.
Test day 3 was a day of disaster. Reasons are now known.
Test day 4 was a day of joy. It works! The DragonWing kept gliding!
00:00 - 00:26 info before 1st flight.
00:26 first flight
02:27 stall
02:42 report of 1st flight by Sietse and preparations for second flight
04:20 2nd flight
07:58 report of 2nd flight
09:26 Jeroen does something that is not good.
09:40 the following day
10:09 first flight of second day
23:44 yells of joy :D
23:50 report of first flight by Sietse
25:22 second flight with same wingtips but a bit more lead up front
37:01 installing the other wingtips [those with a long cord for the elevons] and some comments by Kees
38:21 flight with those wingtips
39:43 right after landing Sietse gives his first impressions.
40:01 report of last flight
40:55 the glider shows in flight how we feel (epilogue)
(acrobatics will not be allowed in the real thing, but ...it is nice to test with the RC glider)
Camera ON RC model
the tested elevons were 1/4 chord
Testing elevon type 7
It was a bit better than the previous ones. But ...still too slow in roll and ...very fragile. It broke during landing. This video was made for red-blue 3D glasses. :)
This day we were planning to test two elevon types. Type 7 and type 10. I suggested type 10 out of curiousity. The other team members suggested type 7. They really totally didn't believe in type 10. "It is a waste of time and money!" They asked to fly thier type 7 before my type 10, because mine was sure to crash. We needed the middle part in good shape to test the second set of wing tips.
Testing elevon type 10
Quickly it becomes clear that this is the best performing elevon. It even steers very direct when power was used with the electrical engine for thrust. So ...we have a winner! Number ten it will be.
The White-edition for Albion Bowers
Albion Bowers and his DragonWing RC model at AMA-event in 2016
I was very very thankful towards Albion Bowers, the NASA-egineer that designed the wing. I made something special for him. The DragonWing "White edition". I am happy to see it is still being used during his talks about Horten designs. I am truly proud about it. It is very lightweight. And ...good looking.
I recall a quote from Al Bowers when we were chatting about the DragonWing. "Koen, you better get used to seeing only topviews of SWIFTs" :) Thanks, Al, for the experience. It is a once in a life time experience. Man, what a adventure!
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EXCELL WITH DRAGONWING DATA (edition 10 mars 2016)