Little-known American Helicopter Prototypes & Projects

[hesham]

From Ailes 19/4/1958,

maybe this one was U-17 ?.

From Aeroplane 1958

 

[hesham]

From Popular Mechanics 1966/5,Mr. Pop Wilson and his autogyro bike.

 

[hesham]

On the back cover of this issue was an ad for Firestone Helicopters that has artwork for the GA-50.

Enjoy the Day! Mark

From these report and site,Firestone XR-14 mock-up.

Firestone XR-14

3/4 right front view of prototype aircraft in exhibit room.

corescholar.libraries.wright.edu

 

[persil]

From these report and site,Firestone XR-14 mock-up.

Firestone XR-14

3/4 right front view of prototype aircraft in exhibit room.

corescholar.libraries.wright.edu

Dear Hesham, I hope you don't mind if I leave here a bigger resolution pictures?

 

[hesham]

Hi,

Mr. Horace T. Pentecost founded Hoppi-Copter Inc company,he designed the HX-1 or
Model-100,a one man copter with two contra-rotating rotors,followed by Model-101 &
Model-102,evolved into the 1950 experimental Firefly with an 18' rotor powered by
tip ramjets.

He also designed a very cheap single seat Helicopter,also there was a Model-103 and
Model-104.

http://blog.modernmechanix.com/helicopters-for-everybody/

American airplanes: Ha - Hu

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Hi,

Hoppi-copter (1945) - The first helicopter designed by Horace T. Pentecost of Seattle was a "back-strap" model intended for military use. Later the American Hoppi-Copters Inc. built other models which had two coaxial rotors and a small engine of variable power depending on the version.

Hoppicopter “Firefly” (1950) - Single place model equipped with a two blades tip powered rotor. It seems that this model did some hovering flights in 1950.

Unknown helicopters

www.heli-archive.ch

 

[Stargazer]

 

[persil]

May be of interest:

ROTORCRAFT.INFO

rotorcraft.info - an online, incomplete rotorcraft catalog

rotorcraft.info

I came across also model 103 - I identify it with having an engine moved below main frame (clearly visible). Model 104 (if I recall correctly) was to be made in England in some cooperation, but I was never able to find any picture which will clearly indicate it as a separate thing)

 

[Stargazer]

I came across also model 103 - I identify it with having an engine moved below main frame (clearly visible). Model 104 (if I recall correctly) was to be made in England in some cooperation, but I was never able to find any picture which will clearly indicate it as a separate thing)

Thanks a lot for this!

 

[persil]

It's amazing what a random search after years can yield:

Pardon Our Interruption...

A pulse-jet Hoppi-copter made by the Capital Helicopters Corp.

In the post here:

https://www.secretprojects.co.uk/threads/nemeth-ramjet-helicopter-design.606/#post-54439

you can find picture of this machine (probably named C1 Firefly, picture also attached)

I tried to fix the perspective of the pictures from ebay and came out with that:

The seller of this item is not very open about where it came from, but after some time I was able to trace down this article. It comes from magazine called Air Trails Hobbies For Young Men, issue from July 1954 (vol 42, No. 4). The article describing "Hoppi-Copter" (this is how it is called there) is on page 16.

Finally, my summary so far:

Capital: Hoppi-Copter - General data - ROTORCRAFT.INFO

rotorcraft.info - an online, incomplete rotorcraft catalog

rotorcraft.info

 

[persil]

May be of interest:

ROTORCRAFT.INFO

rotorcraft.info - an online, incomplete rotorcraft catalog

rotorcraft.info

I came across also model 103 - I identify it with having an engine moved below main frame (clearly visible). Model 104 (if I recall correctly) was to be made in England in some cooperation, but I was never able to find any picture which will clearly indicate it as a separate thing)

This is not straight forward. I Just came on the couple of articles in Aviation Week archives and one said that Model 102 "will" be the production version of currently-being-tested tripod version of Hoppicopter. Like year later an article depicts model 103 (which in my mind was model 102 - with just a battery hanging below pilot) and on the right on the bottom picture is shown flying model 104 - but this is hard to identify - I seems not to have an engine below the pilot like in the version I used to call 103

 

[Stargazer]

I gather the only major difference about Model 104 was the more spaced-out rotors.

 

[persil]

I gather the only major difference about Model 104 was the more spaced-out rotors.

This may also be true, but I still have some other doubts on models 102 -103 - 104.

I am diving a bit deeper right now, and shortly I will post my recent findings and doubts. This thread however is getting occupied by Hoppi-copters too much so I will create a new one dedicated to Mr Pentecost helicopter endeavours

 

[Onehoof]

This is the first time I remember seeing this compound helicopter from Grumman. Anyone have any other information?

I suspect the model coaxial lurking behind it is an early Sikorsky LHX.

Grumman never created an attack helicopter that I ever heard of.