Paul,
I am a 6000 hr helicopter pilot.
I am also a K-Max and Husky pilot, and have been on the Board of
Directors at Kaman Aerospace for 14 years.
The aero flap principle of the Kaman rotor-system is brilliant and
trouble free.  I would heartily endorse its incorporation.  What's
more, most of the original design team is still around for
consultation, if you would like to speak to the horse, as it were.
Just say the word.
-Reeves Callaway


Reeves,

I would really like to see some pix of the Kaman SeaSprite rotor
head.  I've
been digging for info about how that aero flap works and how it
performs in
service.  It looks like an outstandingly elegant way to control a rotor
without hydraulics.  I have read that the SeaSpite is a little tricky
about
adjusting the track of the blades, but there is little info out
there, or I
just don't know where to look.

Steve Brazil


Steve,
I am headed to Connecticut in 10 days for Kaman work.
Let me see if I can extract any relevant drawings.
I did a quick search, and can find nothing, either.

The first time Charlie Kaman showed me the system it was one of those
Doh! moments....

-Reeves

In the mid-1980s, I wanted to design a homebuilt helo which would be a
2-seat, 5/8 scale Husky (to run on the 13B engine!).  I wrote to Kaman
asking for information, and got a nice letter back from Charles Kaman
himself, telling me that the patents had expired, and that he had no
personal objection to my idea.  I never got past the earliest stages
(the kids were coming along fairly regularly, and they had precedence),
but never forgot that letter!

Keith Wood

Hi Paul,
Found a website with a short description of how the kaman rotor flap servo
system works.
http://www.helis.com/howflies/servo.php

Dan

"The servo flap mechanism in essence operates the flap on the trailing edge
of the rotor blade in order to change the pitch of the blade. Mechanical
linkages from the rotor head run through the blade to this small flap and
changing its pitch in much the same manner as that for conventional rotors.
Flap and lag hinges are present as in the conventional helicopter blade.
This mechanism is different in that it does not require any hydraulics
between the pilot and pitch change mechanism because the moment arm is
so large that suitable mechanisms can be designed such that pilot effort
is low. The collective and cyclic pitch system differs in manner of
operation from the conventional configuration due to the use of servo
flaps."

Paul Lamar


All

I've seen that sketch before.  I'm not sure what aircraft it is but it
appears to use a single rod to the servo tab.  I'm thinking of two rods, not
unlike a U-control model airplane.  The Husky and the K-max have rotors on
the order of 48 feet and as such have rotor speeds in the 300 rpm range. On
a small helicopter, the speed will be around 500 rpm and I think that needs
more positive control.

Reeves, I am very eager to see whatever info you can get about the
SeaSprite.

Steve Brazil

Hi Paul,
How will yaw inputs be accomplished using the servo flap system
while in hover mode?
I take it you won't be using an intermesh setup. With the rotor heads one
on top of the other would you need some sort of brake system to create
yaw movement while hovering? Or is there some other way of applying more
or less torque to each rotor head?
In the intermesh setup they used differential rotor pitch meaning they
pitched
the rotor forward on one and the other rotor backwards to make yaw turns
while hovering. Would you use the canard to create yaw? Ah I think I just
answered my own question aye? :-)
Dan
Any ideas guys?
Dan

I think this question is intended for Steve Brazil.
I don't intend to use the servo flap. I intend to use the Air Scooter
trick of changing the thrust vector angle. As far as roll about the vertical
axis it probably can be controlled by the elevons on the delta. The contra
rotating rotors cancel the majority of the torque around the vertical axis.
http://www.rotaryeng.net/VTOL.html