Could the Inflatable Aircraft Concept Be Updated/Modernized?

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sanman

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Back in the 1950s, Goodyear developed its Inflatoplane concept for the US military, using its newly developed Airmat technology. The idea was to create a collapsible/portable plane that could be airdropped to downed pilots for escape, but it was abandoned as alternatives like helicopter rescue became more viable.



But I wonder why it couldn't be revived or even redesigned completely, to serve the civilian consumer market?

Could it perhaps be done as a Part 103 aircraft, since the lighter inflatable body might more easily fit under Part 103 weight limits?

And what about a lower aspect ratio wing-body design, which perhaps might be more suitable for inflatable structures?

Perhaps inflatable structures could be complemented with some rigid load-bearing members capable of folding or collapsing by hinges, or joints, or by sliding.

The main purpose and selling point of an inflatable plane would be to serve as a collapsible and more portable alternative to other recreational ultralight aircraft.
 

Tiger Tim

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I used to think it would be a laugh to build a replica Goodyear Inflatoplane but lately YouTube has been tossing a bunch of wind tunnel test videos of them my way. It’s not apparent in in-flight footage but when the plane is held in place and filmed, yikes! I think a plane made of wet spaghetti would move around less...
 

lelievre12

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Looking at how high pressure SUP boards are these days, that material would be useful for an airframe. Although its actually not that light. Whenever you lug your SUP out of the trunk you'll know what I mean.
 

GeeZee

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I’ve been enamored with the Inflatoplane for a long time and actually saw one once in a small museum at Pax River. I’ve read that one of the biggest problems was the need to maintain a pretty narrow range of inflation pressure. When climbing to even a few thousand feet, pressure had to be released then when descending pressure had to be increased. The 2cycle engine had a small compressor attached that was used to maintain the pressure. Apparently if the engine quit at altitude structural integrity was lost (low pressure) as it descended and the plane would collapse. I suppose a modern version would have a lightweight lithium battery powered compressor that was microprocessor controlled.
 

rv7charlie

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Or the more modern fiber tech available today would allow 'overinflation' so that rigidity just gets better with altitude.

Side data point: Some of the USA's old liquid fueled ICBMs from the 60s had to be kept fueled/pressurized to support their thin skins. (hint hint)
 

sanman

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See this also:



I’ve been enamored with the Inflatoplane for a long time and actually saw one once in a small museum at Pax River. I’ve read that one of the biggest problems was the need to maintain a pretty narrow range of inflation pressure. When climbing to even a few thousand feet, pressure had to be released then when descending pressure had to be increased. The 2cycle engine had a small compressor attached that was used to maintain the pressure. Apparently if the engine quit at altitude structural integrity was lost (low pressure) as it descended and the plane would collapse. I suppose a modern version would have a lightweight lithium battery powered compressor that was microprocessor controlled.
If you can dynamically adjust pressure using a compressor, perhaps you can even use that as an actuator, for variable geometry purposes.
You might be able to deform the geometry by changing the pressure in certain inflated structures.

If you're using a battery, then it could not only serve as a backup power source, but even as an intermediary. So you could have a gasoline engine optimized for a narrow power band simply feeding power into the battery, which could then power electric motors for the propellers, instead of having gasoline engines running the propellers directly.

So the constant-rpm gas engine feeds battery, and battery then feeds various electric motors, whether for propellers or for the compressor that keeps the aircraft at balanced pressurization. In my opinion, a constant-rpm gasoline engine is much less likely to to suffer a stall than one that's directly attached to a propeller and suffering different loads and feedback forces.

If some kind of problem happens, whether due to structural integrity loss or whatever, then also keep a small ballistic parachute onboard, just in case.
 
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raumzeit

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Side data point: Some of the USA's old liquid fueled ICBMs from the 60s had to be kept fueled/pressurized to support their thin skins. (hint hint)
The SpaceX Starship boosters use Atlas "balloon-tank" scheme today, and they use the same material even - stainless steel. Yup, old Atlases look like stainless steel because they are. There is apocryphal story of Werner von Braun himself not believing such a scheme feasible, and Bussart (Atlas designer) having Werner hit side of pressurized Atlas (not fueled, just pressurized) with sledgehammer to try breaking it, and of course Werner could not.

Atlas Mercury orbital rig closest SSTO manned system ever operated (only drops 1st stage engine on way up).

But being one puncture from absolute disaster I think a deal breaker for that technology in flying consumer products.
 

raumzeit

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If you can dynamically adjust pressure using a compressor, perhaps you can even use that as an actuator, for variable geometry purposes.
You might be able to deform the geometry by changing the pressure in certain inflated structures.

What you're describing is pretty close to this thing -> https://www.delta-club-82.com/bible/292-hang-glider-woopy-fly.htm

There is compadre setup to Woopy Fly called Woopy Jump, and I know that thing definitely uses compressors for active inflation management. Its a wing built like a lightweight bounce-house.
 

cluttonfred

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That is very neat, what's it called in English? My Russian and especially my Cyrillic alphabet is pretty rusty.
 

Riggerrob

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If you visit www.secretprojects.co.uk and read the "Goodyear Inflatoplane" thread, you will also find inflatable airplanes flown by Brits, Russians and other Americans.
American Taylor McDaniel towed an inflated glider aloft circa 1930. Test pilot Joseph G. Beugling deliberately crashed it to prove how difficult it was to damage.
The British Army tested a powered, inflated, high-wing, delta plane during the 1950s. They eventually used it to test early radar-invisible concepts (aka. stealth).
A Russian engineer who worked on parachutes also built an inflatable airplane in Leningrad/Saint Petersburg/Petrograd. In 1935, Pavel Grokhovsky built a PG-69 protoype inflatable airplane. Unfortunately Grokhovsky was later arrested and shot by secret police, just another casualty of Stalin's political purges.
 

Riggerrob

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That is very neat, what's it called in English? My Russian and especially my Cyrillic alphabet is pretty rusty.
Reference post #14, it seems that Russians just borrowed a few French words: planeur, parachute and discoplane.
"Planeur" is the French word for "glider."
Since "discoplane" was a new word, ti was adopted by several other languages.
Does the word "discus" dated back to the first Olympic Games in ancient Greece? Back then it was a military weapon thrown at enemies.
 
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sanman

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But being one puncture from absolute disaster I think a deal breaker for that technology in flying consumer products.
What's going to puncture an aircraft flying in the sky? A bird strike? That could smash a windshield too, never mind just cause a puncture.

People do hot air ballooning without suffering any punctures. People fly ultralights with fabric wings, without suffering any punctures.

An inflatable aircraft could have a ballistic parachute system. It could also have a compressor to continue pushing air into the inflatable structure to offset pressure loss.

Also -- what if the front-facing sections or leading edges had some solid cladding on them, to protect them from frontal strikes?
Is it really very likely that an aircraft could be punctured from behind while flying?
 

Riggerrob

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Or the more modern fiber tech available today would allow 'overinflation' so that rigidity just gets better with altitude.

Side data point: Some of the USA's old liquid fueled ICBMs from the 60s had to be kept fueled/pressurized to support their thin skins. (hint hint)
Yes.
That is the basic concept of "tensairity." If a flexible structure has enough internal air pressure, structural components are always in tension, ergo they cannot collapse.
IOW If internal pressure always exceeds outer compression forces, the structure is rigid ... the ultimate in tensile structures.

OTOH Gothic cathedrals are the ultimate compression structures. Since they are largely built of stone, they can only support compressive loads. They built extremely tall cathedrals all loaded in compression. They did not have to worry about side loads (e.g. wind) because all structural members are in constant compression. Flying buttresses helped absorb side-loads in compression, but they were also cleverly pre-loaded with extra weight - in the form of statues - to ensure than compressive forces always exceeded tensile loads.
 

Riggerrob

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Looking at how high pressure SUP boards are these days, that material would be useful for an airframe. Although its actually not that light. Whenever you lug your SUP out of the trunk you'll know what I mean.
I suspect that inflatable SUP are built way over-strength to tolerate the usual abuse of dragging across rocky beaches, etc.
The only limitation on adapting SUP technology to airplanes is that current stitch-through sewing-machines can only make constant-thickness sheets.
I predict that - within 5 years - stitch-through machines will be able to sew variable-thickness airfoils.
 

Riggerrob

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Dear sanman,
Perhaps divided to structure into multiple "cells" like ram-air parachutes. Install one-way valves to ensure that if one cell is punctured, adjoining cells stay fully-inflated.
You will still need an inflight-compressor to compensate for any slow leaks.
 
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