(Kaman Model K-240 , as of 1962 the TH-43E)

 Kaman Aircraft received a Navy contract for the HTK-1 trainer helicopter, a cabin version of the K-225,  on 05 September 1950      ("Kaman Our Early Years", p81)

These 29 HTK-1 helicopters were built in Building 244 , a former National Guard Hangar at Bradley Fld, CT between 1951 and  October 1953

First flight took place on 04 April 1951, but it is unknown which aircraft was involved. Probably this first flight was made by the so-called HTK Dogship, which was flying with civilian registration N400A (see below)

According to  "Kaman Performance", the  "25 Anniversary Issue"  (1945-1970) publication, page 3 : "The first HTK  was rolled out and flown to Anacostia Naval Air Station, Washington, on April 26, 1951".   Two days later :

 HTK 128653 at Haines Point, Washington, DC , 28 April 1951, photo from  "Kaman Our Early Years", p86   

HTK 128653 at Haines Point, Washington, DC , 28 April 1951, photo signed by  Bill Murray, Kaman test pilot  (second from left) , Mr Charles H. Kaman and his wife are 3rd and 4th from the right  ; photo from EBay 2012 auction

HTK-1  128653 Haines Point, Washington, DC    28 April 1951 -  Aviation Week issue 21 May1951  (page copy from EBay2016 auction)

NOTE :  only 1 hr. 40 minutes flight time upon arrival at Washington, DC  from Bradley Fld. , CT

(what does   ", was assembled from parts of three copters."  mean ??)

HTK Dogship  N400A

According to an article in "Aeroplane Monthly" , June 2006 , by Howard Levy , the first development of the XHK-225 was the HTK Dogship, with civil registration N400A.  Would this N400A be built on an existing K-225 airframe with the purpose of having a test aircraft ready before the first production HTK-1 would be available ??  

The title "dogship" used by author Howard Levy may refer to the following : (from the website of  Piasecki Aircraft Corp.)  “………., Piasecki piloted the world’s first successful tandem helicopter. The first tandem was called the "dogship" because it was a flying mock-up, and was flown as a control demonstrator”  (comment by Ragay)

N400A , photo by Howard Levy ,

"Aeroplane Monthly" ,  June 2006, page 65

HTK-1  128653 and  HTK  N400A, unknown date , photo by Warren Shipp, copied from  EBay2014 auction

HTK-1 Research and Development , modifications

HTK-1  BuNo. 128657 , ca. 1953   - Kaman Photo

HTK-1  129302 - "Flying"  April 1953  -

from Ebay

HTK-1  129303 on delivery flight to HU-1 at Ream Fld, CA - here photographed at Ft. Sill, OK in Dec 1952 by Wilbur Bates Jr -

photo coll. W. Mutza

From  “Aviation Week”, 08 Dec 1952 :

Several major modifications set the production HTK-1 apart from the prototype HTK which made its debut at the American Helicopter Society Forum, Haines Point, Washington, DC on 28 April 1951. Changes include shortened tailboom, added fin area, and aerodynamic changes in the rotor blades.  Shortening the tailboom caused a loss of tail movement arm , so the area of the outboard fins was increased from  10 ½  sq. ft. to 12 ½ sq. ft., and ventral and dorsal fins, each of 8  1/3  sq. ft., were added on the tailboom. The production HTK-1 had newly designed blades that are narrower than the old blades, widening at the servo-tab, and tapering toward the tip. The flexible blades are actuated by the servo-tabs, a distinctive Kaman feature.

Pneumatic floats could be fitted as needed, making it an all-terrain helicopter. Thus equipped, it was initially demonstrated to the US Navy on 28 April 1953.

128654 with floats , Apr53 - Kaman Photo 

128654 with floats, Apr53 - photo by Frank Guaditis,

taken from EBay auction 2014 

HTK-1 into Unit Service

First assignment to a NAVY  Unit took place on 22 January 1953 , when HU-2 received BuNo. 129305. Soon followed by HU-1 which accepted BuNo. 129303 on 29 January 1953. These aircraft were used all over the world as utility helicopters, but their intended role, training students, started when the first HTK-1 was delivered to HTU-1  at NAAS Ellyson Field, FL. on 17 July 1953 (BuNo. 129316).

The HTK-1 was so simple to fly that student pilots soloed in that machine after less than two hours dual time. (comment by pilot James M. Middleton - “Rotor & Wing International”,  April 1989 , page 16 ) 

HTK-1  129312 HU-1   "UP 95"  at  Barbers Pnt., HI  in  July 1954 -

photo coll.   W. Mutza  

HTK-1  129313  HU-1   "UP 92" , unknown location and date -

photo by  G. Markgraf  

                                               for  **   %   see the two tables here below

HTK-1 128659  "UR 27"    of  HU-2  , photographed at  NewarkApt  ; photo collection  W. Mutza

HTK-1  129310 "UR 25"  and "UR 26"  on board the USS Orleans Parish  -

  Kaman Photo 328    

HTK-1  129310 "UR 25" June-Sept 1953 on board the USS Tanner -

photo taken from EBay auction 2015 

HTK-1  129315  "EA 13"  HTU-1   photographed at Dayton, OH  September 1954  by  Balogh,  photo collection  W. Mutza

HTK with twin-turbine power 

On 26 March 1954 a production HTK (BuNo 128657) fitted with two 190 e.s.h.p. Boeing 502-2 turbine engines made its maiden flight at Kaman’s Bloomfield plant in Connecticut. The research programme was a joint US Army/US Navy endeavour, but the helicopter wore only Navy markings, and was evaluated at the NATC. The twin-turbine HTK was Kaman’s fifth “world’s first” rotorcraft accomplishment.

Kaman HOK , HTK 128657 with twin turbo engines , K225  N401A , taken at Bloomfield, unknown date - Kaman Photo-753 , coll. A. D. Rita

Twin Turbo Boeing 502 2  - Kaman Photo , coll. NIMH

last update 21/12/2016