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The Dobson Convertiplane - VTOL

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billyvray

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I just found this interesting attempt at a VTOL or VSTOL aircraft. Twin mcCullouque 2 strokes, counter rotating, swash plate controlled props, delta wing, low aspect ratio - I'm not sure what other descriptors it needs. I figured this group would be all over it!
This actually seems like a good prospect. I guess if better powerplants were used, or maybe just more power...I don't know why it failed and can't find out anymore on the internet.

 
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jedi

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Nice project. Would be good to find the Aviation Week article.

I would guess that they were not able to find financing to continue and ran out of time and money. They did a fantastic job up to the end of the video. Definitely an idea ahead of it's time.

I am sure the twin two strokes did not help the long term outllook.
 

Dusan

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Would be good to find the Aviation Week article
I searched for it; It's featured in Aviation Week, August 3, 1953, page 26,27. I could not see the whole article, but a low resolution image of it. Maybe someone has a paper copy.

Really interesting project. It tries to simplify the tilt wing/rotor design to extreme. I wonder how the concept could be applied to Wainfan's Facetmobile, it would be really awesome. Definitely more effective aerodynamically than personal multi-rotors everyone is building today.

 
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Hot Wings

Grumpy Cynic
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All done with slide rule, paper and pencil!
Makes the Riptor project look like a half finished kids Tinkertoy play session.
Also probably as expensive in inflation adjusted $'s. Would be interesting to know the last chapter of this story. :beer:
 

Dusan

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I think this is the same Franklin A. Dobson that was an early pioneer to work on air cushion vehicles in '57. If so, it seems he abandoned work on the delta convertiplane. Excerpt from "Flying Ships: Hovercraft and Hydrofoils" by Malcolm W. Cagle (download for free here: Flying Ships: Hovercraft and Hydrofoils | Malcolm W. Cagle | download):
"One of these early pioneers in the United States was Mr. Franklin A. Dobson, who began his work in 1957. ''My work started as a by-product of a Vertical Take-Off design effort," he said. ''I thought there should be some way to increase the ground effect of a helicopter by enclosing the rotor downwash, so I worked out t·he plenum chamber theory and later the annular jet. At the time, I wasn't aware of work being done elsewhere, either in the United States or Great Britain. ''To test my theory, I built a six-foot model with the help of a friend, using a homemade double rotor from an earlier VTOL experiment, plus a belt-drive from a chain saw engine. One whole weekend was devoted to the job, and the resulting vehicle, while hardly the ultimate in efficiency, checked the performance predictions quite closely."
Mr. Dobson considers that one of his machines was among the first to surpass ''hump speed," in 1963."

Later, he built a hovercraft and sold it as a kit:
 

billyvray

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Yep, Dobson built the little hovercraft also. Plans were once available, but I have been unable to find a set. That would be a fun little project.
 

cblink.007

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How cool is this?? This is the spirit of homebuilding in its purest form. If I remember right, some of the lessons learned from this project were applied to the Sikorsky Coaxial Advancing Blade Concept aircraft over the years, to include the current SB-1 Defiant!

But being a tiltrotor guy at heart, I'll stick to my beloved Osprey!
 

Riggerrob

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Wow!
Mr. Dobson devoted tremendous doses of: imagination, engineering skill, fabrication skills and hard work to produce two credible machines that were ahead of major manufacturers.
Dobson's hovercraft hovers surprizingly well, even without a skirt.

Dobson's VTOL delta had potential.
The high-wing, delta tractor configuration appears to simplify several structural and handling dilemnas suffered by prop-driven deltas.
We are still wondering why so few high-wing deltas have been built by others. One of the few high=wing deltas was the - not very successful - Hustler homebuilt.
 

Urquiola

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Madrid, Spain
Nice project. Would be good to find the Aviation Week article.

I would guess that they were not able to find financing to continue and ran out of time and money. They did a fantastic job up to the end of the video. Definitely an idea ahead of it's time.

I am sure the twin two strokes did not help the long term outllook.
I guess the whole Aviation Weeek archive for back issues is available. About the Dobson Air Car, as published in Mechanix Illustrated, May 1969, Patent US3292721, I'd say its main originality is the niche for pilot and passenger being something like a bathtub, the outer rest of hull being left open, a different arrangement to that of most Hovercraft. He sold the fan and the fan shroud as a kit part, difficult to make for a homebuilder. Perhaps performance would be greatly improved with any of the Wankel Air Cooled Snowmobile engines by Sachs, KM-24, KM-914,...Blessings +
 
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