Re: Increasing duration in F1D - prop settings and back-off

From: jannis1indoor <jannis1indoor_at_yahoo.com>
Date: Wed, 21 Mar 2012 03:51:36 -0000

John and Dezso,

I converted the data to show rpm vs time but don't know how to add attachments to e-mails on this site. I assumed that the times were for 10 revs. Looks like all of these props shift gears at about 8-10 minutes.

Jeff Annis

--- In Indoor_Construction_at_yahoogroups.com, "John Kagan" <john_kagan@...> wrote:
>
> That's good info, Dezso. As I interpret it, you are graphing the number of seconds it takes for a given number of prop revolutions.
>
> I chart the revolutions per minute, so our graphs are vertical mirror images of each other - it took me a minute to figure out why yours didn't look familiar :)
>
> --- In Indoor_Construction_at_yahoogroups.com, Dezso Orsovai <orsid48@> wrote:
> >
> > Hi Tapio,
> > for example...
> > you can change the data in the table. 
> >
> >  
> > Dezso Orsovai
> >
> >
> > ________________________________
> > From: John Kagan <john_kagan_at_>
> > To: Indoor_Construction_at_yahoogroups.com
> > Sent: Monday, March 19, 2012 4:35 AM
> > Subject: [Indoor_Construction] Re: Increasing duration in F1D - prop settings and back-off
> >
> >
> >  
> > Hi Tapio,
> >
> > Launching with no backoff is a good goal. There is a lot of energy in those top end turns - much more than cruise or descent turns. You want all of that energy. Energy = time :)
> >
> > I recommend charting the RPM during a flight. That will give you a clear picture of when the prop starts and finishes changing, and how much it changes. This is a more accurate method than watching the climb - IMO.
> >
> > --- In Indoor_Construction_at_yahoogroups.com, Tapio Linkosalo <tapio.linkosalo@> wrote:
> > >
> > >
> > > Last night when making motors (for F1B...) my thoughts turned to
> > > Belgrade, again. Started to wonder what to do to climb up the ladder of
> > > duration (I'm currently at 26 mins, so next target should be closer to
> > > 30...)
> > >
> > > Comparing my flight profile to the one that John was flying in 2010, I
> > > was surprised to see him taking almost 20 minutes to climb to the
> > > ceiling. My model was at the apex of the flight profile in 10 mins... So
> > > obviously this is where the missing flight time lures. One thing that I
> > > need to fix for next summer is to modify my VP's to take higher max
> > > pitch, currently I'm against the top stop (cannot adjust any further),
> > > and need to take backoff to avoid hitting the ceiling.
> > >
> > > So this is the first question: should I aim to fly with no backoff at
> > > all, and just add the max pitch to control the amount of the climb?
> > >
> > > Second, my props use a "soft" spring with multiple turns. Thanks to very
> > > informative discussion with the Brits last summer, I now understand that
> > > this kind of spring works with a rapid movement from high pitch to low,
> > > and indeed this was showing in my flight profile last summer: after the
> > > apex at 10 mins, the model started descending, until at around 14 mins
> > > the pitch changed, resulting in a shallow second climb and then cruising
> > > down for the rest of the flight. Maybe a "harder" spring of fewer turns
> > > would enable similar action as Treger was showing, with a long cruise
> > > not changing much altitude throughout the middle parts of the flight? I
> > > suppose this would, however, make the adjustment of the spring
> > > pre-tension much more sensitive than with a softer spring?
> > >
> > >
> > >
> > > -Tapio-
> > >
> >
>
Received on Tue Mar 20 2012 - 20:51:38 CET