Raptor Setup

Raptor Heli Info Home Page: Archive: Message #1285

Date: Jun 14 1999 13:45:39 EDT

From: TednLindy@aol.com

Subject: Cyclic Pitch setting

The recent suggestion for increased response is basically sound, EXCEPT that
the 6.5 degrees mentioned should refer to the change in the MAIN BLADE pitch
at full cyclic throw, not the angle of the PADDLES which will be in the 16-24
+ degree range. See the paddle throws that are included with various set ups
in the CSM Simulator.

When doing your setup for aerobatics, keep in mind that there are two
limiting factors:

Blade Stall angle of attack of the main blades; and

The mechanics of your particular helicopter/engine/servo/radio combination.
The mechanical limits are those where the mechanics and servos don't bind or
stall when the "sticks are in the corners,"
and the maximum pitch your engine will pull in a constant climb in normal or
inverted flight at 1900 RPM.
{Reference material: Mas Tech series of articles of 1994 and 1995 in Rotary
Modeler}. I am away from my "library" or I would quote issue numbers.

I use the following procedure, using an MA or Century pitch gauge, flybar
lock and appropriate levels after the basic pitch window (-12 to +12) has
been established mechanically with all servo arms, linkages, etc., at the
level or 90 degree position with Zero Pitch at 50% on the transmitter at

Set up the flybar lock and using the transmitter collective set the main
blade pitch to Zero on the gauge. Leave the collective alone, and with the
flybar over the tailboom, adjust the appropriate Cyclic Throw ATVs to +/- 6.5
degrees on your pitch gauge, Then turn the head so that the main blades are
over the tail boom and adjust the other Cyclic Throw ATVs to +/- 6.5. This
should give you close to maximum available cyclic control while avoiding
blade stall.

Since the average model blade stalls in the 12-16 degree range depending on
its design, you want to keep the total collective pitch PLUS the total cyclic
pitch change to something under 16 degrees.

This is the reason that the "Set Ups" page of MHT usually shows a pitch
window to be -9, 0, +9 or -10, 0, +10 for most of the experts for aerobatic
flight modes using 60 sized helicopters and 1600-1750 RPM.

-8, 0, +8 is not unusual for Thirties because they usually perform better at
1900-2000 RPM, particularly if the cyclic throw is set to more than 6 or 7

It should be considered that some of the more exotic blade designs stall at a
higher angle of attack, say 16+ degrees as compared to the 14 degrees or so
of many stock kit blades. The shrink wrapped varieties can stall as low as 12
degrees depending on the design. They also have a higher drag which puts more
load on the engine preventing the higher RPM ranges from being attained.

With a typical mechanical pitch window of 24 degrees total range, you can
set Hover, Idle Up 1 and Idle Up 2 to provide those parameters that suite
your flight modes and allow different Collective/Cyclic combinations.

For maximum cyclic response for a 30 sized bird in Idle Up2, or Stunt Mode 2
you might consider a combination such as:

Head speed of 1900+ RPM
Running under about 1850 RPM degrades the cyclic response noticeably in a 30
sized unit.)
Pitch curve: -8, -4, 0, +4, +8
Quality glass or CF blades
Cyclics on high rates set to produce +/- 7 degree cyclic throw.
A well set up and tuned engine/exhaust combination.

(It helps to be close to sea level <G>. Total available power drops off at
approximately 5+% per thousand feet)

Of course for flying in the Normal mode or Idle Up 1, a more gentle set up
should be used that you might find more comfortable. Pitch curves resembling
-4, 0, +4, +8, +Max, and appropriate throttle curves, and cyclics set on low
rates of about 75% of those used at Idle Up 2 with whatever expo that is
comfortable should do fine for the average pilot.

Keep in mind that many pilots fly a -8,0,+8; -9,0,+9 or -10,0,+10 pitch curve
for both Normal and Idle Up modes with the only differences being in the
throttle curves AND the amount of Expo applied.

All of the above presupposes that the operator has and is familiar with the
basic measurement tools and has access to a Sky Tach at least occasionally.

I am currently running some tests with a variety of blades at 6340' MSL where
even minor changes in engine settings, blade design, exhaust systems and fuel
make major changes in performance.

Up here the stock woodie is almost unusable out of the novice flight range.
While awaiting some V 3D blades from Vic Campbell, the best combination that
I have found on my Raptor:
Helimax Pipe
30% Coolpower fuel ( for additional cooling )
Generic Glass 560 symmetrical blades

Ted Wilds


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