LMH-110
I wanted a heli that would be able to
withstand arguments with terra-firma with little damage
because I really HATE crashing. I know this is
illogical, and is slowing me down, but I seldom do it
with my fixed-wing models and don't want to do it with
my helis either.
Reading the news-groups prompted me to
get a Lite-Machines 110, and I've made a number of
modifications as suggested by various sources:-
1) I replaced the fragile standard
canopy with one from a Concept EP made from 'car-bumper'
material. To mount this I added a simple plywood
stand-off mount behind the mast (see pictures).
2) I wrapped the tail-boom with
insulation foam tubing to prevent 'dings' to it caused
by impact from the rotor-blades.
3) Having test-flown the 110 on my
back lawn, I
removed the Arlton mechanical gyro from the tail,
modified the tail pitch drive with a couple of collets,
and added a Futaba GY-501 gyro on a plywood platform on
top of the crutch. The Arlton gyro had a terrible
throttle to rudder coupling which I have almost
eliminated with the 501. It also gives me heading-lock
which I always use!
4) I found I couldn't get above 40%
gain with the Topaz servo I had on the tail, so decided
to order a Multiplex micro speed MC/V2 servo for the
tail. Having fitted this, I can now get the gain up to
60%. I think that to improve it any further I will need
to mount the tail servo at the rear of the crutch (or on
the boom) to get a shorter pushrod. As there doesn't
seem to be any play in the existing pushrod, the other
possibility, or even probability, is that the flexible
LMH tail blades are now the culprit.
Two pictures of the 110 with the
Concept EP canopy.
This one shows the plywood mount I
added behind the mast to mount the Concept EP Canopy.
And
the plywood mount for the GY-501 on top of the crutch
assembly.
And
this is the mod. to the tail pitch assembly using two
collets and one of the existing drive arms.
Today I took the LMH for its first
flying session at Windsor Great Park. How else can I
describe it but FANTASTIC!
During
the 8 flights I made of some 8-10 minutes each, I
managed to progress from tail-in hovering to Lazy-8's
and then on to something resembling true Figure-8's. I
noticed that the tail still wagged slightly when the
tail was pointing into the fairly strong wind, even with
the gain at its best value of 40% - maybe the faster servo
will help.
At this point a bit
of over-confidence caused my first 'heavy-landing' when I tried to
do a nose-in landing - resulting in the heli on its side
and the vertical tail fin knocked off at the cyano
joint. The engine was still running so I decided to
simply pick up the heli, put the blades back in
position, and take off again. It flew perfectly, and I
can't say I noticed any difference without the tail fin.
What other heli would have survived even such a minor
crash without substantial damage?
Towards
the end of the session I managed to get on to oval
circuits in front of me, in both directions, and started
flying figure-8's the 'other way round' with the heli
going away from me in the centre of the 8.
I
finished the session when the batteries got too low to
fly without yet another charge and left feeling that I
had made some real progress at last.
First flights with Multiplex servo.
Have now fitted the faster servo and a
1600mAH NiMH battery pack. Gain can now be turned up to
60%, and I managed to get in a couple of flights during
the week just before it got too dark.
Discovered
that the LMH doesn't have any reserve in the blades if
the engine cuts. First time, a slightly lean mix caused
a cut at about 10 feet - The heli fell like a brick, but
stayed the right way up and just bent its undercarriage
- Fire up and fly again.
Second
time, I deliberately ran out the dregs of the tank at a
mere 1 foot off the ground. The heli still bounced hard
from that height. So, obviously try not to have
an engine cut in flight, one of the disadvantages of a
fixed-pitch heli.
I have now setup a model of the LMH-110
for RealFlight Deluxe, which you can download as LMH-110.heli.
Copy this to your RealFlight\Planes directory and see
what you think. If RealFlight doesn't show the model in
the heli/airplane list then make sure that your browser
hasn't added a .txt extension.
The LMH-110 model shows a very marked
tendency to pitch up when slowing from FFF. If any RFD
experts have any idea how to cure this then please let
me know.
Took a couple of hours off work today due to the unusual dry weather (we're water-logged
here in the UK), and had my second full session with the LMH and came
away feeling I'd made real progress again.
This time I managed to get on to rectangular circuits, side-on take-offs
(but not landings yet), tight figure-8's with the heli virtually on its
side and pulling G fun-fly plank style, nose-in hover down to about 10
feet with the wind on the nose of the heli for minutes at a time, and
some passable stall-turns and loops (actually figure-9's) to finish. The
'loops' are pretty scary with the LMH as the thing gains very little
height in the 'up' portion and falls a VERY long way on the down portion
with the most incredible (good) blade noise. I wouldn't like to try and
roll it, despite Lite Machines claim that it's possible, so that will
have to wait for the Raptor.
I did have a few 'heavy-landings' during the session, the last of which
happened when I inadvertently ran out of fuel at 30 feet (I was enjoying
myself so much I honestly didn't hear the timer) and the heli fell out
of the sky. It fell into some pretty soft ground with NO damage and I
carried on flying.
I also had a few 'hard takeoffs' when trying to take off nose-in! I
think I'm going to have to make up some trainer gear before I try that
again.
This page was last updated on September 06, 2006
