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deskpilot

Well-Known Member
Joined
Jun 30, 2009
Messages
1,132
Location
Morphett Vale, South Australia. Just south of Adel
Hi folks. A couple of weeks ago, I received a pm from Billyvray asking for more info on my staggered biplane design. He suggested that I might publish details for all forumites to ponder, criticise or just get a good laugh. :mad2: No, really, he didn't say that. Just joking.:roll:

Anyway, this is the tale so far.

I have designed a few planes before and they always got too complex eg,

Bolt_1st_mockup_front_quarter.jpgBolt_1st_mockup_rear_quarter.jpg The DeMansfield Bolt with it's prop rotating around the tail boom (still love this design but it isn't easy to acheive a safe, un-stayed version.
Twin-boom pusher2.jpg An Unnamed and unfinished single seat pusher
VT-ICE iso.jpg VT-ICE a 'way out there' Vectored Thrust-Inverted Channel Experimental
As now.jpg EagleRay, a 'double delta' or truncated taper fighter look alike based on the John Dykes JD-1 Delta.

At that point, I decided that if I'm going to fly my own aircraft, I needed to get back to basics and aim for something that fits our 95-10 category (very similar to your 103) Not exactly cheap and nasty, but hell,.......... cheap. Now I've always wanted something out of the box. Not some clone of a clone of a clone, so I started to work on a simple version of Andre Stark's AS-37. A close spaced, staggered biplane with ailerons on the 45degree end planes. The wings were spaced and staggered a 2/3's cord and the plane was powered by a Citroen flat four boxer engine driving contra-rotating props. He had 2 seats and the aircraft proved to be flyable but was under powered so he later changed the engine for some thing more powerful.

Construction-rear quarter [800x600].jpg Initially I was going for very light and simple but, after some research and advice from Pylon500, I started to redesign it to have cantilevered wings using ali for spars and ribs. Nothing wrong with that but the part count went up horrendously and I became very aware that I was going to exceed our 300 Kg MTOW. Consequently, I've now changed to a simple single wing variation but kept the same power configuration. As yet unnamed here id my latest rendering.

Front quarter single wing.jpg rear quarter single wing.jpg Single wing in need of an engine.jpgMy next job is to model the engine, a borrowed Rotax 508, 4 stroke that is apparently based on the 503 2 stroke. Whatever, should be powerful enough at about 45hp (hope my memory hasn't let me down here)

Bill was interested in my method of achieving a light weight contra drive system so here it is. Simplicity itself.

Contra-rotating props drive system.jpg I hope you can see my intent. The main drive chain goes over and under and over again so the any 2 adjacent gears are rotating in opposite directions. Secondary chains feed out to the props. Feel free to copy or modify for yourselves.
I have designed a simple differential braking system using bicycle disc brakes. Unfortunately I haven't be able to get it to be proportional as well. On the control stick, you simply twist the bake lever left or right then squeeze the lever for left or right brake only application. Keeping the lever centralised, applies both brakes together.

Brake lever assembly [800x600].jpgBrake lever assembly underside [800x600].jpg If the weight gets out of hand, this will be the first deletion in the design.

I am still working on the side mounted control stick (makes it easier for an old phart like me to climb aboard or fall out of when dismounting :roll:)
I'm also still figuring out a simple but strong, method to attach the outer wing panels. I don't want to spend half an hour rigging and de-rigging every time I fly. Got me some ideas but need to sleep on them some more. The centre section of the wing is approx 7.5ft, just inside our max width for towing.

Well that's it for now. Would you believe it, the wife wants to go shopping........again.

By all means ponder and criticise. If you feel you need laugh, just don't tell me. OK?
 
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