Horace T. Pentecost and the Hoppi-Copter

with 18 comments

Horace T. Pentecost and the Hoppi-Copter HX-1

I’d completely forgotten about this little piece of family history until my brother Wade reminded me of it. In the 1940s, our great Uncle Penny invented a backpack helicopter called the Hoppi-Copter, and one of his prototypes is in the Smithsonian.

Horace T. Pentecost’s first attempt, the HX-1, never actually flew as intended, but that’s the model I see most often in pictures of Uncle Penny. It’s also the model that’s in the Smithsonian (and which is currently on loan to the Pima Air & Space Museum in Tucson.) Evidently, the initial version of the Hoppi-Copter was doomed by the fact that landing on one’s feet and keeping one’s balance might be difficult while wearing a contraption made of spinning blades that could easily splinter if they struck the ground. The placard near the Hoppi-Copter at the Pima Air & Space Museum reads:

“The Hoppi-Copter is part of the long quest for a truly low cost personal flying machine. It was designed by Horace Pentecost of Seattle, Washington during World War II. He marketed it to the U.S. military as a replacement for the parachutes used by paratroops. The design consists of a small 20 horsepower motor powering two counter-rotating set of rotor blades, strapped to the back of the pilot. The greatest weakness of the design was its use of the pilot’s legs as landing gear. If he stumbled during landing or take-off the blades would quickly turn into thousands of potentially lethal splinters as they pounded themselves into the ground. This was, quite correctly, seen as ridiculously hazardous and the idea was quickly abandoned.

“Built by Horace Pentecost in 1945 and briefly tested by the U.S. military. It made about 20 flights with the pilot tethered by safety cable to prevent him from falling down. It was donated to the National Air & Space Museum in 1951 and was placed on loan to the Pima Air & Space Museum in 1996.”

The next model of the Hoppi-Copter featured a seat and wheels.

Hoppi-Copter 101

Version 2 also merited a mention in the April 7, 1947 issue of Time magazine:

“Ever since Icarus, and in spite of what happened to him, men have dreamed of strapping wings on themselves and taking off like the birds. Airplanes have never completely satisfied this desire. The plane itself does the flying; the man only rides and steers. Gliders are only half the ticket.

“Last week the ancient dream showed headline-hitting signs of coming true. At a Philadelphia meeting of the American Helicopter Society, Horace T. Pentecost told about the “Hoppi-copter” (see cut), which he has been developing in Seattle. It is a helicopter stripped to essentials: little more than a seat, landing wheels and two horizontal rotors revolving in opposite directions. The power source is a 35 h.p. engine with two opposed cylinders like an outboard motor. According to Mr. Pentecost, ‘the required blade adjustments to render typical three dimensional helicopter flight have been coordinated into a single control handle placed conveniently in front of the operator.’

“Total weight (not counting Mr. Pentecost): 173 lbs. The Hoppi-copter should ‘retail for little more than the better modern motorcycle.’ Helicopter experts would be more enthusiastic if they had seen it flying, but no performance records have been made available.

“But the designers have incorporated one important safety feature. Icarus made the mistake of flying too near the sun, which melted the wax that held his wings together. The Hoppicopter’s announced ceiling is a modest 12,000 ft.”

The third version of the Hoppi-Copter put the engine under the pilot’s seat and became the subject of an article in the January, 1951 issue of Mechanix Illustrated (along with some rather fanciful illustrations.)

"Hellicopters for Everbody," Mechanix Illustrated, Jan. 1951

"Hellicopters for Everybody," Mechanix Illustrated, Jan. 1951

"Hellicopters for Everybody," Mechanix Illustrated, Jan. 1951

According to the Smithsonian, after ultimately failing to get any interest from the military, Pentecost later tried to market the Hoppi-Copter as “sport aircraft,” and that “just as the company was ready to place the Hoppi-Copter into production, Pentecost’s ex-wife forced him out of the company when she managed to become a majority shareholder.” Tim McAdams’ AOPA blog says that Pentecost’s ex-wife (aka my great Aunt Charlotte) owned 45% of the company (per her divorce settlement with Horace) and became a majority shareholder by teaming up with Uncle Penny’s lawyer, who owned 10%.

After that, nothing much happened until 1956, when investors tried to revive the company, but that didn’t work out either, and the Hoppi-Copter seems to have faded into ancient family history and an exhibit that the Smithsonian loans out to other museums. I have no idea what happened to Uncle Penny or the later incarnations of his machine. Wish I knew more.


Written by Dean Jeffrey

August 3, 2011 at 12:09 am

Posted in Relatives

18 Responses

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  1. I would greatly love to speak to you . I have worked with your uncle’s first helo that is at Pima A&S. I have gathered a 3″ thick packet of info on the craft and blueprinted the unit.


    Michael Jeffries

    August 22, 2011 at 11:53 pm

    • Hi Michael

      Can you please contact me at




      October 5, 2011 at 1:46 pm

      • Did you ever talk to Michael?

        David M

        June 6, 2015 at 9:18 pm

    • Michael can you email me?

      David M

      June 6, 2015 at 9:19 pm

  2. Do you know if your uncle left any journals or letters about his time at Purdue University? Thank you!
    Please contact at

    Chris Cleland

    April 5, 2013 at 6:41 pm

  3. Hi Dean, My great-grandfather, Frank Goodwin, Seattle, was an investor in the Hoppicopter. One of my grandma’s cousins remembers it.

    Kerry Serl

    December 16, 2014 at 10:40 pm

    • Hi Kerry, thanks for commenting. Very cool to hear from someone who has a connection (however slight) to Pentecost.

      Dean Jeffrey

      December 17, 2014 at 3:20 pm

  4. In the American helicopter journal Magazine ot around 1950 something there isi s a good article and pics of the model with the triumph engine, when it was in the UK…………….Curtis


    February 10, 2015 at 9:58 am

    • Thanks, Curtis, I’ll check it out. The library at the university in my hometown actually has a complete run of American Helicopter.

      Dean Jeffrey

      February 10, 2015 at 5:19 pm

      • Hi Dean, the article on the american version is November 1947 (when i was born) and the uk one is October 1950, I know a couple of strap models are in meuseams, i wonder what happened to the other models?……………….Curtis


        February 11, 2015 at 9:43 am

  5. You’ve probably seen this, but just in case… Always wondered if we’re related; if he’s descended from Scarborough Pentecost (Brunswick County, VA 1737 – 1795), that would be a “yes”.


    April 14, 2015 at 2:56 am

    • Hi Gregg, yes, I have seen that, actually, but thanks. I haven’t looked at that in a long time. I assume that the model in the picture is the one that’s on semi-permanent loan to the museum in Tucson.

      Dean Jeffrey

      April 14, 2015 at 11:21 pm

    • You’re very gracious for not pointing out that your post had a link to it already (which I didn’t notice until after I posted) 🙂 On a side note, I first learned of Horace at the Smithsonian in the same room where my wife’s uncle Frank T. Piasecki (“pioneered tandem rotor helicopter designs and created the compound helicopter concept of vectored thrust using a ducted propeller”).was profiled


      April 14, 2015 at 11:28 pm

  6. I think Horace was the father of my friends Chuck and Mike Pentecost. We were my friends growing up in San Pedro, CA in the sixties and seventies. Their Dad got a divorce from Chuck’s mother in the sixties and moved to Santa Barbara where I understand he sold real estate. Horace was an engineer for an aerospace company and designed armaments. He was also a sailor and he owned a couple of boats and I often went sailing with them. He had a home made cannon on board using a anti aircraft shells in case “he was attacked by pirates”. Awesome. Never saw a Hoppi and he never talked about it that I remember- I had no idea until I saw it in the Smithsonian myself He was also a ham radio operator judging from the station they had in their home. He also had two daughters Judy and Katie.He wasn’t a pleasant man from any of the times I met him.

    Richard Reeves

    August 21, 2016 at 3:45 pm

  7. Richard, thanks for posting this! Very much appreciated.

    Dean Jeffrey

    August 23, 2016 at 2:38 pm

    • I can probably put you in touch with Chuck or Mike if you want. I was looking at the old Pent home in Google earth and it’s changed a bit- still a hell of a view of the pacific and Catalina island. Chuck is s machinist and Mike is longshoreman.

      I moved away around 1973 to go to school- went back regularly until I got married, kids career thing. Haven’t seen Chuck in years but I have relatives who know him. San Pedro has grown a lot but the old timers still know each other. Nice place to grow up as kids. I doubt there was any better place in the world.

      Sent from my iPhone

      All the best Richard Reeves


      Richard Reeves

      August 23, 2016 at 4:48 pm

      • I gotta admit these helicopters coaxials are awesome I would love to get every bit of information I can get on this and would be deeply appreciate it thanks. David

        David Mikesell

        August 23, 2016 at 7:05 pm

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