First approx for optimum rubber wt is double airframe wt (6g on LPP). Twice the energy of 1:1 and only 50% higher wing loading.
Adding in the reduced drag coefficient of the faster flying (higher Reynolds Number) the ideal ratio is closer to 2.5:1.
Not easy to do, especially w/10" stick. One Peanut Scaler used motor 7X hook distance w/scale size prop + plenty of rubber clearance & it flew fine.
Food for thought,
H
To: Indoor_Construction_at_yahoogroups.com
From: ykleetx_at_gmail.com
Date: Fri, 5 Mar 2010 05:11:50 +0000
Subject: [Indoor_Construction] Re: Hints for Cat IV LPP flying
Thank you, Bill, Mark, and Steve. I decided to follow Mark's advice and fly on a 1/5 motor. I launched with very little back-off between .6 and .8 in-oz, but I could not hit 30'. The best I could do was 20' with a time of 2:45. Steve's record is safe! When I "tossed" the plane to 25', the time was 3:05.
The plane climbs immediately at launch on the high torque, so I think my motorstick is stiff enough. (But .8 in-oz is A LOT of torque!) I'm going to adjust the stab's incidence to be inline or a little negative relative to the prop thrust. I think this should lengthen the climb. Right now, the stab's incidence is positive and probably reducing the climb.
I was also thinking about increasing the length of the rubber say from 2.5g to 3.0g. You guys have recommended 2.5g or less. Is 3.0g obviously the wrong way to go?
=Kang
--- In Indoor_Construction_at_yahoogroups.com, steven richman <topdawggt2006_at_...> wrote:
>
> First Hey Mark, Sorry I have not been around. Thanks for the shout out.
> Hopefully one of these days soon I will actually get back into flying. I do
> miss it greatly. I still have all my stuff, so hopefully its just like
> hopping back on a bicycle right?
>
> As far as CAT IV LPP. When I was making my run at the record, I did a lot
> of testing at USIC, using 1/5 motors. I think it is very beneficial, but
> expect times to be higher on your 1/4 motor testing, than actual times will
> be. This is mainly becuase the rubber wont bunch up and "distribute" the
> same as a full size motor, if that makes any sense. I also did not use
> sleeves on my record flights. Not sure if that would have helped or not.
>
> I belive my prop pitch was around 18, id have to do some searching. But it
> was a very high flaring prop. I think 2-2.5 grams of rubber is about right
> from my experince. I think my record flight was on .086-.088. Last comment
> is on launch torque. I launched at almost 1.1 In. Oz. With a flaring prop
> you will need much more torque to get it to the roof. I don't think .4 in
> oz. with any prop (unless pitch is very low) will get you anywhere near the
> roof. Hope that is somewhat helpful!
>
> -steven richman
>
>
> > For starters, I was wondering the approximate range of rubber size to use,
> especially to get to the ceiling. My prop is now set at 22" pitch. How does
> a 20" loop of .093" sound? Or does high ceiling flying require something
> like 24" of .080"? I plan on practicing using a 1/4 motor in the gym and
> later at Tustin to test.
> >
> On Wed, Mar 3, 2010 at 8:33 PM, ykleetx <ykleetx_at_...> wrote:
>
> >
> >
> > Thank you for the feedback. I'll start tonight with
> >
> > 1/4 motor of .60g will try .093" and .083"
> > ballast for full 2.5g motor -- plane weighs 5.6g at launch
> > prop pitch 18.5"
> >
> > And see how it goes.
> >
> > I'll ask about the motor sleeve later :-)
> >
> > -Kang
> >
> > p.s. I've been flying my daughter's 2010 SO plane. (competition is over.)
> > The best I could do is 3:45 at 30' no touch. Let's see how the LPP goes.
> >
> >
> > --- In Indoor_Construction_at_yahoogroups.com<Indoor_Construction%40yahoogroups.com>,
> > "Bill Gowen" <wdgowen_at_> wrote:
> > >
> > > I'm not a great LPP flyer in Cat 4 but I would guess you would do best
> > with something in the range of 2 1/4 to 2 1/2 grams of rubber in a motor
> > that is 20" to 22" long. You will probably need to use sleeves at both ends
> > of the motor. Your model should be able to handle a launch with something
> > over .4 in-oz of torque. You may need to use less pitch to get sufficient
> > climb but this will depend on your prop design and how much it flares.
> > >
> > > Maybe others will chime in with more or different info.
> > >
> > > ----- Original Message -----
> > > From: ykleetx
> > > To: Indoor_Construction_at_yahoogroups.com<Indoor_Construction%40yahoogroups.com>
> > > Sent: Wednesday, March 03, 2010 5:27 PM
> > > Subject: [Indoor_Construction] Hints for Cat IV LPP flying
> > >
> > >
> > >
> > > I have the opportunity to fly in Tustin in April, though I've never flown
> > indoor before, other than coach Science Olympiad. I plan to enter LPP.
> > >
> > > I would appreciate any pointers on how to fly in a CAT IV site like
> > Tustin. I now fly in a middle school gym where I can practice 30' no touch
> > flights.
> > >
> > > For starters, I was wondering the approximate range of rubber size to
> > use, especially to get to the ceiling. My prop is now set at 22" pitch. How
> > does a 20" loop of .093" sound? Or does high ceiling flying require
> > something like 24" of .080"? I plan on practicing using a 1/4 motor in the
> > gym and later at Tustin to test.
> > >
> > > Thank you.
> > >
> > > -Kang
> > >
> >
> >
> >
>
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Received on Fri Mar 05 2010 - 05:28:40 CET