The prop shaft is the wire that goes through the bearing and attaches to the rubber motor. What kind of pitch gauge do you have? If it's a commercial gauge it should have markings for setting different pitches. The pitch is the theoretical distance that the prop would travel in one revolution. You determine the pitch by measuring the blade angle at a specific distance from the center of the prop. If the blade is set at an angle of about 39 degrees measured 2" from the center of the prop then that corresponds to a pitch of 10. If your 18.5cm prop blades are set at an angle of 23 degrees at the tips then that also is a pitch of 10.
----- Original Message -----
From: jimranor7
To: Indoor_Construction_at_yahoogroups.com
Sent: Wednesday, February 21, 2007 12:26 AM
Subject: [Indoor_Construction] Re: SO Wright Stuff
Oh, I tried to change the prop pitch by gripping the center hub and
twisting the prop spar. Thank you. I have a pitch gage and I will
change it like you said. Could you explain me the pitch around 10
thing? And my plane has some rips on the film surface, should I put
some very small pieces of scotch tape on them? Could you define the
prop shaft? sorry.
--- In Indoor_Construction_at_yahoogroups.com, "Bill Gowen"
<b.gowen_at_...> wrote:
>
> In the files section there is a movie clip showing changing the
pitch of an Ikara prop with heat. You need a pitch gauge to use this
method. The blue tape shown on the prop blade is there to keep the
heat from damaging the blade.
>
> The more usual way to do it is by gripping one side of the prop
spar with 2 pairs of pliers and twisting the spar. You still need a
pitch gauge to have any idea what your results are. If you go a
little overboard with this method the prop spar will break. You can
usually fix them with thick CA.
>
> I would suggest starting with a pitch of around 10 which would be
39 degrees measured at 2" from the prop shaft. If you're using a
large Ikara cut down to 18.5cm your pitch is probably a lot higher
than this.
>
> If you absolutely can't get a pitch gauge then you can do this:
> Twist the prop spar on one side of the hub a little bit to get that
blade to a lower pitch. Hold the prop shaft between your fingers and
find a line on the floor. Move your hand and rotate the prop until
you can line up the tip of the prop blade with the line on the floor.
Then - without moving your hand! - rotate the prop 180 degrees and
compare the angle of the second prop blade with the line on the
floor. Twist the spar for the second blade until both blades will
line up with your line on the floor. This is a very crude way to
adjust a prop but it can work if you're careful.
>
> ----- Original Message -----
> From: jimranor7
> To: Indoor_Construction_at_yahoogroups.com
> Sent: Tuesday, February 20, 2007 11:31 PM
> Subject: [Indoor_Construction] Re: SO Wright Stuff
>
>
> Actually, thank you for the reply, (I'm sorry)I only dared to get
it
> up to 110-120 turns with the 15:1 ratio so like 2000 turns (sorry
i
> said 200 turns) in total. Could you tell me a good way to change
a
> propeller pitch?
> -- In Indoor_Construction_at_yahoogroups.com, "Samiur Rahman"
> <groundhawk2006_at_> wrote:
> >
> > I'm pretty sure your pitch is too high, or you are using too
thin
> rubber. I
> > suggest buying fatter rubber if you think you can't change the
> pitch. I
> > assume that the diameter for your propeller is 18.5cm, I
suggest
> going at
> > 35-37 degrees for the pitch, trying using a pitch gauge. if
you're
> able to
> > get close to 200 turns, you're definitely using REALLY thin
> > rubber.....you're probably using 1/16 rubber. Try using 0.085,
> which should
> > go upto 150.
> >
> > On 2/20/07, jimranor7 <lejinuni_at_> wrote:
> > >
> > > Hi, I am a high school student. I have a Harlan Cruiser 67
and
> I cannot
> > > get it to climb up to the ceiling. I hear people talking
about
> hitting
> > > the ceiling and falling, but my plane will only go up like 6
or 7
> feet
> > > and start descending. The width of the rubber band is
whatever
> came in
> > > the kit, and the pitch is as it is for I don't know how to
change
> it
> > > without breaking it (I broke 2 of my extras so far). I change
the
> pitch
> > > by twisting it in the center, but it never works. The plane
has a
> > > positive angle of attack. I wish I can see it go up and hit
the
> ceiling
> > > because the plane isn't that impressive when it isn't flying
> high. The
> > > propeller is not spinning fast enough, i think that is why.
What
> shocks
> > > me the most is that I put more 100 turns with the 15:1 winder
and
> close
> > > to 200, and it went only 6, 7 feet. The best time I had was
34
> seconds.
> > >
> > >
> > >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
[Non-text portions of this message have been removed]
Received on Tue Feb 20 2007 - 21:37:56 CET
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:44 CET