Why the intermeshing rotor helicopters are so few?

[persil]

Has this type of blade control also been used on helicopters other than Kaman?

Of course. But in production machines there is only Kaman.

The very first ever (although I am not sure) to use this solution is most likely the Curtiss-Bleecker SX-5-1:

Other early example is one made by Mr Corradino d’Ascanio:


There are other legit test helicopters:

Kjeller: PK X-1 - General data - ROTORCRAFT.INFO

rotorcraft.info - an online, incomplete rotorcraft catalog

rotorcraft.info

Kjeller: PK X-2 - General data - ROTORCRAFT.INFO

rotorcraft.info - an online, incomplete rotorcraft catalog

rotorcraft.info

And some other projects/prototypes:

Marinchenko Yu. { Маринченко Ю. } - General data - ROTORCRAFT.INFO

rotorcraft.info - an online, incomplete rotorcraft catalog

rotorcraft.info

Borshduha S. { Борздуха С. } - General data - ROTORCRAFT.INFO

rotorcraft.info - an online, incomplete rotorcraft catalog

rotorcraft.info

KhAI: KhAI-25 { ХАИ: ХАИ-25 } - General data - ROTORCRAFT.INFO

rotorcraft.info - an online, incomplete rotorcraft catalog

rotorcraft.info

And most likely even more.

 

[sferrin]

Many USAF HH-43 in Nam were used as fire safety birds, blowing away fire for fire safety crew to reach crashed aircraft engulfed in flames, something they excelled doing.

When I was a kid in the 70s Hill AFB had some of these. I remember them because their sound, they were weird looking, and when I saw them they were relatively low and heading straight West from Hill to the range.

"HH-43B aircraft were assigned to the 1550th Aircrew Training and Test Wing, a tenant of Hill Air Force Base, to train combat crews from 1971–1976. The HH-43B on display was manufactured in 1963 and served in Japan, Oklahoma and lastly at Hill Air Force Base for training purposes. In 1988, it was put on display at Hill Aerospace Museum."

 

[Richard N]

View: https://youtube.com/shorts/_fCfsnIg-v8?si=63y_1-2I5hVM7m-L

 

[persil]

View: https://youtube.com/shorts/_fCfsnIg-v8?si=63y_1-2I5hVM7m-L

There was even full-size helicopters made in this layout (apart from Kaman)

Two of the latest that come to my are Mr DeGraw's Hummingbird:

DeGraw R.: Hummingbird - General data

DeGraw R.: Hummingbird available data

rotorcraft.info

And Mr Clybouw's CW105F Flamingo:


This one was recently undergoing restoration in Belgium.

Clybouw W.: CW105F Flamingo - General data

Clybouw W.: CW105F Flamingo available data

rotorcraft.info

 

[Nicknick]

Looks faster than it was, glad about the restauration!

 

[publiusr]

My prime reason for intermeshing arrangement would be the elimination of:
-Unnecessary long airframe.

That was all you had to say.
Blackhawk vs tractor/trailer in length?