RTFM Aero-Bike Brisbane, Australia

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rtfm

Well-Known Member
Joined
Jan 3, 2008
Messages
3,194
Location
Brisbane, Australia
Hi,
After having been knocked back several times in my design/build of the Razorback - I am once again tooling up to begin iteration the umteenth. And looking out a good number of years till I get it into the sky. So i got to thinking that what i need in the meantime is something cheap, quick and simple so that I can fly while I build a more ambitious project. Hence the Aero-Bike.

I was inspired in this direction by the recent and exciting thread about a modern day motorcycle of the air thread. There were many really nice designs there, and so I got to thinking that an aero-bike might just be the way to go. Four designs appealed to me in this general category:
  1. The Ison-designed Sky-Bike
  2. Valley Engineering's Backyard Flyer
  3. The French Cubchel by Daniel Dalby
  4. Which in turn is his take on the Affordaplane
From the Sky-Bike I took the cabin layout, seating position and rather rakish cowl

From the BYF I took the Swing Wing

From the Cubchel I took the simple aluminum tube and gusset construction technique, and the main gear

Finally, the Affordaplane provided me with the inspiration to go with a single gauge of AL tubing throughout (unlike the Cubchel).

Each of the planes above offered something I wanted, but each of them had at least one significant drawback. The Sky-Bike was welded 4130 tubing. I don't weld, not really that keen on learning (at least to the skill level required). Local inquiries turned up terribly expensive pricing to get a local welder to do the job for me. And to have a welded fuse shipped to Australia was ridiculously expensive.

The Cubchel really appealed to me, and I bought a set of plans. But they are all in French, and even with a French speaking wife, we were making heavy going of it. Add to this the fact that 6060-T6 is completely unobtainable in Aus. I got the OK to use 6061-T6, which also happens to be unobtainable in the required 50mm x 50mm tubes. Finally - support was virtually non-existant, with emails never getting answered, and requests for information on the (mainly French) forum barely any better.

The Affordaplane had a number of design issues in my opinion, and the BYF was only available as a fully built plane.

So I decided to use the Cubchel construction method, but use a different extrusion. I managed to find 6061-T6 in 80mm x 40mm and settled for that throughout. There is no 3mm 6061-T6 plate in Australia, so I settled for 3mm 5083 marine grade. Rather than importing AN hardware, I settled for the 12.9 grade hardware available locally, which actually exceeds AN spec but a nice margin. Metric. The major departure from all of these planes is my choice of airfoil (I'm going with the Riblett GA 37A415) and the construction technique. I'm building a one-piece composite wing. No flaps or ailerons. These will be provided by an external Junkers foil acting as both flaps and ailerons (flaperons). This makes for a very simple wing construction.

Because the wing has a fully glassed skin, torsion will not be an issue, and because it will be bolted to the airframe both fore and aft, I only require a single strut for each wing half. These struts (faired 4130 tube) attach with a simple bolt at the fuse, which can be quickly removed, allowing the wing-attach point to swivel so that the strut lies from it attach point along the outer portion of the wing where it can be attached securely for storage. A simple pin fixes the rear of the wing to the roof, and a finger-tight nut (secured by a pin, of course to prevent unscrewing in flight) completes the forward attachment. The flaperon controls are via aluminium tubes to horns on the fuselage end of the two-piece foils (ie two halves). These attach again via a simple fork-and-pin arrangement and secured with a pin. Very simple to build, strong, secure and easy to remove.

The aluminium arrived at the end of last week. I picked up the fasteners later the same day.

Prep time 30 hrs (not counted in build hours):
15 hrs to construct a full scale wooden prototype out of 70mm x 35mm lumber (of which I happen to have a healthy supply). It took many failed attempts to get the angles just right and get everything fitting together nicely. I then used these full size templates to line up the drop saw with the perfect cutting angles to attack the aluminium tubing.

I also spent the best part of another 15 hours drawing and then cutting each gusset out of 10mm hardwood plywood. I drilled all the bolt holes, ready for transferring to the sheet AU.

Day 1: 2hrs
Using my templates, I cut up two 6.5m long 80mm x 40mm 6061-T6 pieces of tubing. It worked out almost exactly, with only about 300mm of tubing left over. Ta-daaa!

That's how far I've got. Only 2 hrs, but the airframe is cut out, and ready to be bolted together.

I am waiting for a new bi-metal band saw blade to arrive so that I can rough cut the AU sheet, and then clamp these to the gusset templates and router around them for a perfect match.

Regards,
Duncan

Concept design drawing (please excuse the crude CAD - this is NOT my forte...)
AeroBike design concept.jpg
 
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