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]
Received on Tue Feb 20 2007 - 21:11:45 CET
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