Back Monte-Copter Model 15 Triphibian

Model of Monte-Copter Model 15 Triphibian Helicopter

Monte-Copter, Inc. was incorporated in June, 1953, to develop a light helicopter featuring the "cold-jet" type of rotor tip-drive.

The company's first prototype was the Monte-Copter Model 10, which began its test programme in 1955. It has since undergone considerable development and in its current form is known as the Model 12.

A brief description of the Model 12 is given below, together with full details of the production development, designated the Model 15 Triphibian, which was scheduled for completion late in 1959.


This aircraft began life in 1955 as the two-seat Monte Copter Model 10, powered by a 135hp Lycoming O-290-D2 engine, driving a two-blade rotor with servo-control surfaces mounted at 90° to the blades. At that time it had small fixed wings to off-load the rotor in forward flight and a tail-boom carrying twin fins.

After initial tests had been completed, this airframe was modified into the Model 10A by removal of the wings and cabin skin and replacement of the Lycoming piston-engine by two Continental Model 140 (Turbomeca Palouste) air compressors. These engines were mounted on each side of the fuselage and were used to supply compressed air to rotor-tip nozzles, from which the air was ejected without any form of combustion, to turn the rotor.

Further modification of the airframe has led to the present Model 12, with the fuselage skin replaced and a single rudder, working in the jet efflux, instead of the former tail-boom. In this form, it has been flying successfully since May, 1958.

No specification details are available except that the Model 12 has an empty weight of 454kg and a normal loaded weight of 635kg. Its rotor has a diameter of 32 ft. (9.75 m.)


Developed from the Monte-Copter Model 12, the Model 15 Triphibian is a three-seat light helicopter with a "cold-jet" type of rotor drive, in which the rotor is turned by ejecting compressed air from nozzles at the blade-tips, without any form of combustion. The prototype was scheduled for completion late in 1959. The Model 15 is of very simple design, with a fiberglass boat-type hull to permit operation from water as well as land. It has small delta wings to offload the rotor in forward flight. Fuel tanks on the wing-tips serve also as stabilising floats during water operations.

TYPE: Three-seat amphibious helicopter.

WINGS: Small delta wings to offload rotor. Conventional ailerons.

ROTOR SYSTEM: Two-blade main rotor with fully-articulated semi-rigid all-metal blades, attached to hub by specially-designed serrated fittings. Spherical bearings at pitch and flapping hinge. Area of each main blade 1.11m2. Total disc area 94.76m2. No anti-torque rotor.

ROTOR DRIVE: Cold-jet type, in which compressed air is ejected from blade-tip nozzles. Rotor/engine r.p.m. ratio 340/ 35,000.

FUSELAGE: Aluminium and magnesium bulkhead and keel structure, with fiberglass skin.

LANDING GEAR: Non-retractable tricycle type. Torsion bar shock-absorbers. Goodyear wheels, size 5.00x5. Goodyear hydraulic brakes. Wheel track 3.05m. Wheelbase 2.13m.

POWER PLANTS: One Continental Model 141 air-compressor, rated at 200 gas h.p, mounted in rear fuselage. Fuel in wings and in wing-tip tanks, with total capacity of 136 litres. Oil capacity 4.5 litres.

ACCOMMODATION: Pilot and two passengers in enclosed cabin, with forward-sliding canopy. Baggage compartment with capacity of 0.79m3. Provision for carrying one stretcher and attendant.

Jane's All the World's Aircraft, 1959-60

Monte-Copter Inc. was established in 1953 in Seattle to design and build light helicopters. The first design was the Model 10, which was a two-seat machine with a large bubble canopy and a tailboom mounting a tailplane with large twin rudders. The two-blade rotor had control paddles similar to the Hiller system. It was driven by a 135hp Lycoming O-290 engine which generated cold airflow to the rotor tips. This piston engine was then replaced by two externally-mounted Turbomeca Palouste turbojets. The prototype, N68P, flew in 1955 and was later modified to become the Model 12, with a single tail fin. Monte-Copter then built the three-seat Model 15 Triphibian (N69P) which flew in 1960. This was a very streamlined machine with a boat-shaped fibreglass fuselage, forward-sliding canopy, small stub wings with sponsons to house the main wheels and a small full depth rudder. It was powered by a 200hp Continental gas generator housed in the rear fuselage feeding compressed air to the rotor tip nozzles.

R.Simpson "Airlife's Helicopter and Rotorcraft", 1998

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Technical data for Model 15 Triphibian

Main rotor diameter: 10.97m, overall length: 4.65m, overall width: 3.35m, height to top of rotor pylon: 2.52m, weight empty: 545kg, weight loaded: 907kg, max speed: 158km/h, cruising speed: 120km/h, rate of climb at sea level: 335m/min, ceiling: 4570m, normal range: 160km, range with auxiliary tanks: 290km

Comments1-20 21-40
Tad Nitasaka, e-mail, 05.04.2022reply

Though flight tests were claimed, there don't seem to be any photos of the Monte-Copter actually flying.

Ron Rogers, e-mail, 04.10.2021reply

I went to school with Monte Ramme and we were told the Monte Copter was named for him by his Father.

Dianna Bishop, e-mail, 05.09.2020reply

I also have shares bought November 1,1961 and April 4, 1969 any value please let me know total shares 400

Anonymous, 14.04.2022 Dianna Bishop

The company does not exist, and has no value. Therefore, the shares are worth zero.


Dianna Bishop, e-mail, 05.09.2020reply

I also have shares bought November 1,1961 and April 4, 1969 any value please let me know

Dan, e-mail, 14.02.2015reply

I am guessing that shares in this company have no value except as curiosities. With that in mine I'd like have few shares. Share owners might try selling them on ebay. Ran across patent 3417824 where a pancake gas turbine was going to be used in the rotor hub along the lines of the Wagner Rotorcar. Anybody out there work on this configration? I like the You Tube on the Monte Copter has a real might have been quality about it. When the book comes out on this project I'll a copy.

Gayla Schroeder, e-mail, 25.11.2012reply

All of the rights to the Monte-Copter were signed over to Boeing when the company folded. Mr. Ramme has passed away and his immediate family lives in the Seattle area. There are one or two of the Copters still around and as far as I know, at least one is still operable.

Karen, e-mail, 05.09.2010reply

I have 200 shares bought on September 14th 1956. Are they
worth anything?

Joe Dedera, e-mail, 29.09.2010reply

I also have stock in Monte-Copter, Inc. and have the same questions as these folks. Please let me know where I can find information about the value of these stocks. Thank you.

Gene Curry, e-mail, 19.05.2011reply

Looking more closely, it's obvious the picture on this page is that of a model, not of the real aircraft.

Dan, e-mail, 12.05.2014reply

Was there any connection between the Monte Copter and the VOLJET 585? If Boeing bought the stock sounds like a possible big paday!

Gene Curry, e-mail, 15.11.2011reply

All of those holding stock in this no-longer-existing company are owners of zero. It went out of business, and therefore has no value.

jack vander waal, e-mail, 09.02.2014reply

I use to work for the company back when we were actively testing the chopper The Model 15 is now located in a museum at the Ramona airport called Classic Rotors in Ramona California 92065 Their web site list the hours when open

Bharat, e-mail, 26.05.2023 jack vander waal


Please let me know how to get in touch with you


jack vander waal, e-mail, 16.08.2023 Bharat

e mail info


Maurice Holmes, e-mail, 12.07.2010reply

I also have shares of stock in Monte-copter since the 50's and 60's (200+) Are they worth anything?

Tipjetheli, e-mail, 17.09.2012reply

Hi I am looking for this rotorcraft. In any condition. Please help me look for it. Also please help me find the rightful owner of the design and technology. My email or

Teresa LeBeau, e-mail, 28.04.2010reply

I have 54 shares dated 1958. Would love to know anything about them.

tina stricklin, e-mail, 06.04.2010reply

My father also had stock in this company. What has happened to it?

Gary Murray, e-mail, 04.03.2010reply

After going through our late mother's papers, my sister and I found 40 shares of Monte-Copter stock. Are they of any value today?

Gene Curry, e-mail, 23.10.2009reply

I worked for Mr. Ramme and Monte-Copter for the summer of 1958. It was my first job out of college, before going on to graduate school. It was a small, but very interesting company. Lots of tension and doubt about its ability to raise money and keep going. I did some stress calculations on the body hoop frame and on the stub wings.

Norm Hower, e-mail, 29.04.2009reply

Are Stocks in this company of any value.

Ron, e-mail, 26.03.2009reply

We have 20 shares dated 1st of June, 1965.. Any value to these shares? Was Monte copter sold to another company?

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