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(Return to) High wing triangulated mount

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rtfm

Well-Known Member
Joined
Jan 3, 2008
Messages
3,900
Location
Brisbane, Australia
Hi guys,
I searched for a thread to post this in, and discovered that over the years I have created not one, not two but THREE separate threads dealing with the ups and downs of designing the Razorback. From freewing, to fixed wing, from low wing, to high wing, to mid wing. Tail dragger and trike. I really need to get one of the moderators to concatenate these different threads.

One of the designs I was very sweet on some time back was a high wing, but with the wing attached to the fuse via two struts (in the usual place) together with a third rear strut attached to the roof. At the time there was considerable debate about whether this configuration (essentially a "free" standing wing) would be sufficient, and after some debate, the wiser heads decided that yes, it would be, but that there was no way to make the rear strut sufficiently rigid to ensure the wing remained where it was supposed to.

I moved away from the design with some reluctance, and opted for a mid-wing design. Not that it really mattered at the time, because I had months (it has turned out to be years...) of building and perfecting the plug before I needed to actually DO anything about the wing configuration.

However, the recent discussion about designing a compact airplane which could fit into a 20 ft container, has got me thinking about my high-wing design again. I have posted some sketches of the concept below. Please note, these are art works, not engineering drawings. I have tried to be as representative of the concept as possible, but that's all.

Essentially, the design has the single piece wing attached to the airframe with two struts as per usual, and to complete the fixture, the rear tip of the wing is attached to the roof of the airframe. This provides a triangulated attachment, and is completely sufficient to hold the wing in position. As I mentioned, the weakness of the design is in making the rear strut rigid enough, since all wing twisting moments will need to be resolved at this point. And then it occured to me, that while a single rear strut would not be up to the task, TWO angled struts, securely bedded into the body of the plane and angling up to the roof WOULD provide sufficient authority, since each of these rear struts would be under tension, not bending forces. I've been back to the plug, and mapped out where the two rear struts would be positioned, and it all works out very elegantly. So here are the sketches. The benefits of this arrangement are many:
  1. Very easy to attach the wing
  2. Extremely convenient to uncouple the rear fixture (a single AN bolt), uncouple one of the struts (another AN bolt), swivel the wing on the second strut, and fix the wing along-side the fuse for easy storage. In fact, the entire plane could be stored in a container under 7 ft wide. This is probably its chief attraction. Storage suddenly becomes far less of an issue. And with some thought and careful design, storing the wing could be a five minute job for a single person.
  3. No worries about correct angle of incidence of the wing. This is ground adjustable!
There are drawbacks, of course...
  1. More difficult to route the controls
  2. Controls would probably need to be cables, not rods. Pity.
  3. It is a high wing - and not as sexy as the mid-wing configuration (IMO)
Razorback pivot wing concept Dec 25 2012.jpg

The wing (just over 50 ft^2, just over 55lbs) will probably need a supporting brace or two when stored, but that's no biggie.

Please comment, and tell me if you think this idea is worth pursuing.

Regards,
Duncan
 
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