#uh-34

H-19 Chickasaw

H-34 Choctaw

It seems like an odd design choice and terrible for aerodynamics but there was a very good reason for the design. It mainly had to do with the engines available.

The late 1940s and early 1950s were the start of the jet age and only cutting edge fighters were being equipped with turbojet engines. These centrifugal flow turbojets were fairly powerful but unsuitable to be converted for use in a helicopter. Instead, helicopters of the age had to make due with radial piston engines that were still widely in use.

Radial engines were well developed by this point and decently powerful but still couldn't match the power to weight ratio or compactness of a jet.

Their size and shape made them tricky to apply to a helicopter. In an airplane they can easily be mounted on the nose or within round nacelles on the wings for streamlining.

But in a helicopter they would take up valuable space in the center of the aircraft. Helicopters are finely balanced machines that essentially 'hang' on a single point beneath the center of the main rotor. Weight has to be carefully distributed fore/aft, and left/right to keep the center of gravity as close as possible beneath this point. The engine and transmission gearbox being the heaviest single components meant that they needed to be close to the center to stay within balance limits. But with such a large and round engine occupying that space, that meant there was little to no room left for a central cabin.

So the solution was to put the engine at the front of the helicopter in the nose and raise the cockpit to look out from above it, then place the main rotor closely behind the cockpit.

This short distance reduced the impact of the engine's weight by giving it a small lever arm. Then the rest of the helicopter behind the main rotor would have a longer lever arm to balance out that weight. This is the same principle as balancing a scale with different weights on each end by moving them closer or further from the fulcrum.

Looking at these helicopters from the side and using the main rotor as the fulcrum you can tell they are balanced much the same.

Now with the engine out of the way and the helicopter in balance, the space directly beneath the main rotor was free to use as a cabin for passengers or cargo. And because it was so close to the main rotor loading and unloading had a minimal effect on the center of gravity.

This layout was used until the late 1950s when jet engines were converted into turboshafts usable by helicopters. The smaller size and power to weight ratio quickly made radial piston engines obsolete and all but the smallest of helicopters were designed with them in mind.

A USMC M48 Patton keeping guard as a helicopter evacuates the wounded during Operation Starlite, 1965.

Col. Big John LaVoy passed away Easter Sunday Morning. He will be missed. John was he CO of HMM 364 in late 1963 and led 364 into combat for the first time in Vietnam. 

The funeral Mass will be at 10AM on Friday April 25th.  It will be at St Albert the Great Catholic church in Reno Nv. 1250 Wyoming Ave. 89503

Video by, Pat Kenny and Dave Magee  

Video by, Pat Kenny and Dave Magee