Paul,

I'm still looking into the possibility of a vertical installation for a
helicopter.  I would be absolutely elegant if it could be made to work.
What would you think of installing three teflon buttons, one inch diameter,
or larger, near the apex inside the rotor edge seals on what would be the
lower side of the rotors.  Would there be enough oil between the rotor and
the side plate that the buttons would ride on an oil film?  Where are the
thrust bearings on the crankshaft?

Steve Brazil

Hi Steve,
Some thoughts on a helicopter application.
1. Most automotive design engines have little or no thrust bearings.
Rotational power is transferred to a transmission and that is where
the thrust is usually reacted against. The engine/tranny "joint" is
usually even splined to avoid putting thrust loads on the engine
bearings. You need to accomodate thrust absorption in your helicopter
transmission design.

2. In a vertical orientation you also need to consider oil return.
In a 13b slightly less than a quart of oil "disappears" in a running
engine. Some is in the oil pump, some in the pressure lines feeding
various bearing areas, some fills the oil filter, and a lot is in
the rotors cooling them. Most of these places "gravity drain" back
to the oil pan after shutdown. Only a thorough study of Mr
Yamamoto's book will provide insight to the drainage pathways.

3. Oil return and thrust handling are just some of the problems
you'll encounter. You may work for a long time to resolve either
problem adequately. Time resolving problems is time not flying,
so I would suggest you make as few problems for yourself as possible.
If you keep the engine orientation horizontal many of your oiling
and percieved rotor wear problems go away. Find the "lower unit"
for a 200 HP outboard motor and your thrust problems go away.
The "lower unit" will turn the power 90 degrees and provide a gear
reduction as well. Another problem gone. Your "engineering" effort
will consist of developing an adapter plate and reworking the
outboard's drive shaft to provide connection to the e-shaft.
(Probably, shortening and cutting a spline on the "lower unit's"
drive shaft, and fabricating a floating, internally splined collar
with splines that mate with the e-shaft on one end and the drive
shaft on the other.)

4. Keep in mind, this is the world of "experimental" aviation, and
many "experimentors" would rather tinker than fly, so you need to
address your specific goals, also.   Dave M



Hi Paul and Steve,

I
am currently working a project to use the 13B on a Helicopter as well andwould
like to throw in a few of my project ideas that you might find useful.

1.
Engine Mounting:
The
engine will run in a normal Horizontal position and mounted in tandem on two
cross members of the airframe

2.
Drive Mechanism:
Will
be driven by a Mechanical Clutch same as in a manual transmission engine (to have the ability to
disengage the engine for running and fine-tuning on the ground without
spinning the Main Rotors and also dampen the torsional vibrations from the
engine). I also incorporated a Sprag Clutch mechanism at the Final Drive end to
ensure Autorotational landing (A safety requirement for Helis so you donâ??t drop
out of the sky peradventure the engine quits in operation).

3.
Transmission:
Here,
I am using just the Bell Housing, an adapted Input Shaft from, similar Friction
Clutch mechanism, all from a manual transmission gearbox and, an axle differential. The Input Shaft is
connected to a Cog wheel that drives a toothed Belt which then drives another
toothed Cog wheel attached to the main transmission unit at some reduction ratio. My
main Transmission is simply a modified automobile axle differential. Thisunit
turns the drive line into a 90deg drive system for the Main Rotor while providing further engine
speed reduction. A coupling off of this will drive the
Tail Rotor mechanisms.

4.
I am still working on the Main Rotor/Propeller Blades, will definitely beof a Composite
material but the ones out there seems to cost quite a bit; any ideas on how to
get around this without breaking the bank?

Regards,
Chidi Okonkwo