Re: Question for John Kagan

From: <joshuawfinn_at_gmail.com>
Date: Wed, 30 Jan 2013 23:29:01 -0000

Leo,

 My comments are based on the published plans that you've seen. In 2010, Treger was flying at 20" tip pitch and 2 degrees incidence. That is not an easy thing to do--I've tried hard to do it and have failed miserably.

I can tell you after a lot of digging through photos with a fine-toothed comb, watching every video I could find of the relevant models, etc, that Schramm's model appears to be the same as his Cat I record design, and Treger's model at least looks the same as his 2010 design, though that is harder to confirm because I couldn't find as much good, solid footage of his plane. We do know that he has been using the 2 degree incidence since at least 2008, but his motorstick and prop changed significantly between 2008 and 2010.

 As for Schramm's plane... all appearances based on the recent INAV article, video/photos of the Cat I flight, and video/photos of the 2012 flights, are that his plane has not changed significantly. He was definitely using a narrow prop in Cat I. I could do some numerical tricks with the photos, but doubt we would learn anything. Prior to 2008, it appears that Schramm was using a wide variety of propeller designs, most quite wide, until 2008, when he switched to a much narrower outline.

 All this is based on my own digging...if you find something different, I'd definitely be interested to know.

-Joshua Finn

--- In Indoor_Construction_at_yahoogroups.com, "Leo Pilachowski" wrote:
>
> Josh,
>
> How do you know the in flight numbers, such as the decalage and in flight prop pitch for Treger's and Schramm's 2012 WC planes? Are there plans for Treger's plane published other than the 2010 plane. Has a plan for a more recent (2012 perhaps) Schramm plane been published yet?
>
> Leo
>
> --- In Indoor_Construction_at_yahoogroups.com, joshuawfinn@ wrote:
> >
> > >
> > > I haven't figured it out what is making the difference in those two models yet, but I think it is going to come down to the normal, basic stuff: surface alignment, drag, prop efficiency, rubber energy, etc.
> > >
> >
> > One of the few similarities I notice between the two models is that their similar area distribution. Both achieve significant effective wing taper through their chosen method, and both have large stabs.
> >
> > There is a similarity of propellers, too, but what gets me is that Treger is able to fly at such a low prop pitch and only 2 degrees differential between wing and stab. I have a prop with a similar pitch distribution and minimum pitch, and let's just say that even on a reasonably stiff model, I still have to use half again more incidence just to keep things stable.
> >
> > Good flying,
> > Joshua Finn
> >
>
Received on Wed Jan 30 2013 - 15:29:26 CET