Weight, Wing loading, power loading, etc... (Re: Re: Weight rules discussion ( my opinion))

Sun Feb 27 08:19:19 AKST 2005

More power is almost always good.  More power with a proportional increase
in weight is usually bad (if for no other reason the noise level goes up).

A better power to weight ratio is always good and what we really want - and
that is why the favored powerplants in pattern are the ones with the highest
power to weight ratios (and generally cost the most).

Wing loading -
- planes with light wing loadings typically fly nicely over a much broader
speed range - put another way, they handle extra weight better when the
plane slows down (likely because the ideal amount of power is not available
because of the extra weight of the plane).
- wing loading is always a compromise - high wing loadings are better for
snaps, spins, and but not as good for flying relatively slow.
- Very high power to weight ratios minimize the change in speed in different
flight regimes - allowing a relatively higher wing loading with less
detriments.  This is exactly why the trend in new designs has been to
smaller wings - the power to weight ratio has gone up, allowing a higher
wing loading to fly nicely.  And the wings have also gotten smaller to
maintain the same wingloading as the number of composite (lighter) planes
has increased.

I would never add weight (except as an experiment) to my plane to increase
the wing loading (even tho the increased wing loading might be an overall
benefit) because it would decrease the power to weight ratio.  I would
instead reduce the wing area - increasing the wing loading, and increasing
the power to weight ratio.  Yup, I've done this - I intentionally built my
Dash Five (years ago) with clipped wingspan (down to about 800 squ from
830), and then subsequently chopped several inches off the span to improve
snaps and spins (down to abou 770 squ).  Power to weight ratio was a
non-issue - The warmed up Webra 60 spinning a 13x13 at 9300 pulled the 7.5
lb with no problems whatsoever.  More recently, I clipped the wings on the
EMCs I flew several years ago - the first I clipped from 1150 to about 1115,
and the 2nd was clipped to 1100 (10.75 lb planes).  I probably would have
clipped a bit more, but at that time, I thought the wing would look a little
too stubby.  Probably not an issue with current designs.

Dave

----- Original Message -----
From: "Mike Hester" <kerlock at comcast.net>
To: <discussion at nsrca.org>
Sent: Thursday, February 24, 2005 11:42 PM
Subject: Re: Re: Weight rules discussion ( my opinion)

> Just to chime in, I had 2 identical planes a couple of years ago. One was
> DEAD on 11 lbs, the other was right at 10.5. Same exact set up on both
> planes, except for the light one had digital servos.
>
> Here's what I found: the heavy one was easier to handle in the wind. It
just
> took less correction. But there's a catch, keep reading. The light one was
> far better in calm air, and had better vertical both ways. I ended up
using
> a higher pitch prop on the heavy plane, and flew it faster. The other one
> was better for calm days, but I didn't spend too much time with it.
>
> The big difference I suppose: I don't fly FAI. Yet ;)
>
> Momentum made the heavier plane present better, but I could still slow it
> down when I wanted to. I didn't really notice much difference in pulls and
> down lines for instance, but the vertical was apparent. I solved this, as
I
> said, with a higher pitched prop and just flew it faster overall. And the
> heavier one was easier to land, but this was an 1150 inch wing too.
>
> Not exactly scientific, but just something I DID make note of, my
> observations.
>
> -Mike
> ----- Original Message -----
> From: "Jim Ivey" <jivey61 at bellsouth.net>
> To: <discussion at nsrca.org>
> Sent: Thursday, February 24, 2005 11:19 PM
> Subject: Re: Re: Weight rules discussion ( my opinion)
>
>
> > Matt
> > The 12.5 lb dead pig in the sunshine will get better scores because it
> > doesn't appear antsy.
> > Like Dave L says the bigger  the plane the better. I agree here.I also
> > agree if you keep the same wing area and raise the weight the wing
loading
> > changes.You can keep the same 2meter limits with more wing area and have
> > the bigger plane Dave talks about. None of these suppositions were in
the
> > original thread.>
> > If Bob has 2 of the same type planes, same wing area one 9.5 lbs and the
> > other 12.5 lbs I still say the 12.5 would have the advantage of being
> > smoother in the wind(blows at every contest).Does this make it illegal?
> > Only if the CD weighs you.
> >
> > Jim Ivey
> >> From: Rcmaster199 at aol.com
> >> Date: 2005/02/24 Thu PM 11:04:15 EST
> >> To: discussion at nsrca.org
> >> Subject: Re: Weight rules discussion ( my opinion)
> >>
> >>
> >> Jimmy, I've read Don Lowe's columns for years and his rationale (one
that
> >> I
> >> agree with) is that a light plane bounces more but damps quicker than
the
> >> heavy  plane.
> >>
> >> I don't doubt that increasing the DR wing loading by 15% as you  did in
> >> your
> >> experiment, would likely result in better flying fro that plane. It
> >> would be
> >> more interesting to know what the wing loading was and is before and
> >> after
> >> the change.
> >>
> >> Now translate that to a 2 meter job and see what happens. Try
increasing
> >> the
> >> weight of your standard pattern model by 15% and see what it does. How
> >> does
> >> the wing loading compare to your DR b4 and after the changes?
> >>
> >> I'd be interested in that experimental result
> >>
> >> Matt
> >>
> >> In a message dated 2/24/2005 10:44:50 PM Eastern Standard Time,
> >> jivey61 at bellsouth.net writes:
> >>
> >> Bob
> >> I  assume you want to disregard the 11 lb limit. You will have
advantage
> >> over
> >> the  9.5 lb plane. The 12.5 lb plane will be much more stable in the
wind
> >> than the  9.5 lb plane. The engines of today will handle the heavier
> >> plane just
> >> as well  as the 9.5 lb plane.   The difference is you're more stable
> >> because
> >> of your weight. Now if you throw in the weight limit 11 lbs that makes
> >> you not
> >> legal.
> >> I have a 6.25lb Daddy Rabbit that I had to add 1 lb lead to the CG  to
> >> calm
> >> the plane down so I could fly it smoothly .
> >> Same thing.
> >> Don't know if this is a rational reason to be legal or not,but there is
> >> an
> >> advantage to a heavier plane.
> >>
> >> Jim Ivey
> >> >
> >> > From: "Bob  Pastorello" <rcaerobob at cox.net>
> >> > Date: 2005/02/24 Thu PM 10:19:36  EST
> >> > To: <discussion at nsrca.org>
> >> > Subject: Re: Weight rules  discussion ( my opinion)
> >> >
> >> > Let's say I decide, for my own  reasons, that I want to fly a 12.5lb
> >> > (dry)
> >> 2M pattern airplane against 9.5 lb  (dry) 2M pattern airplanes in
Masters
> >> class.
> >> >
> >> > Somebody,  anybody, give me a rational reason why I should NOT be
> >> > "legal"
> >> to fly at a  sanctioned event?
> >> >
> >> > Bob Pastorello
> >>
> >>
> >>
> >>
> >>
> >
> >
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>
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