Maybe some of the why(s) be hide what you are seeing would help more
than a pitch number? Over the years that I have been flying, I have
found pitch to be a relative thing, with the exception of F1D I do not
generally measure my pitch(not advocating this approach) . The
rational be hide this that wood especially, and plastic too, will
deform in the air. So, to find out the actual pitch of an Indoor prop
in flight is rather difficult.
There are a lot of nit picky things that affect the efficiency of an
Indoor model, but the goal is to pitch your prop at the angle that
will be most effective through the majority of the flight. This Is why
we trim for cruse. However, unless your flying in a ballroom, getting
up to the right height will matter for the over all time. start off
with a relatively low pitch and low torque, for SO perhaps a 1.5PD, or
if your prop blades' cross section is larger than an inch, I would try
something around 1.3PD. Start off with approximately half winds, from
the low pitch setting you should see a few feet of climb and then the
model should settle in a cruse. If the model does not climb then try a
slightly thicker motor. once the motor is matched to the prop,
gradually increase torque until you get the height you want. If the
model will take the torque okay, increase the pitch slightly to allow
for more winds in the motor to get to the same height. After this the
model should be close to where you want it time wise. from there take
out warps and adjust trim to get the time you need.
The reason that you will see an increased energy consumption rate as
pitch is drop is that energy of the motor is being expended at a more
rapidly. Thus, you get more air speed, and ultimately height. The
faster that energy must be expended to stay in the air, the less time
you will get.
When trimming the model, look for a nose up attitude throughout the
cruse, that is a good indication of whether the prop pitch is high
enough to pull the model, or if the nose is down, the model is
underpowered typically.
Also, if you are using a can formed prop, There will be a limit at
which the prop becomes too inefficient to fly. This is because the
angular speed of the prop differs from root to tip, and as pitch is
increased the tip begins to stall on the outer blade elements. The
prop blades forward motion will be canceled out by the drag from the
tip stall.
Nick Ray
11/29/06, Brant Fredrickson <brantfredrickson_at_yahoo.com> wrote:
>
>
>
>
>
>
> A veteran flyer once told us to watch how the model flies and increase or
> decrease the pitch accordingly. Unfortunately we didn't ask what we should
> look for in the model's flight. We have noticed when the pitch is way too
> high the model won't climb and if it is a little too high, it takes a higher
> torque to reach the ceiling. Is the optimal pitch is the one that takes the
> lowest torque to reach the ceiling?
>
> Last year we stumbled onto a pitch that seem to work and optimized the
> rubber width to that pitch. Did we have the process backward? Should we have
> picked a rubber width for the ceiling height and then optimized the pitch to
> the rubber width? As a beginner I certainly don't have the answers to these
> questions.
>
> www.BrantFredrickson.com
> mailto:RealEstate_at_BrantFredrickson.com
> Century 21 Homestar, Cleveland, Ohio
> home office 440-442-5866
> mobile 440-983-1173
> fax 440-442-3678
>
>
Received on Wed Nov 29 2006 - 12:30:38 CET
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:44 CET