SEN 923 - 30 Dec 2004
Category: Archive 2004
Table of Contents
Does less lift equal less drag - Barker
Historical Notes on Notes - Mate
Lift Drag Discussion - Segrave
Getting Hold of Verbitsky - Lorbiecki
Desert Challenge - Norton
Does less lift equal less drag
I have not followed this thread closely and the old ones are now deleted so
I will just throw in a couple of brief comments. If I have missed something
important by not paying attention earlier then I am sorry!
Most airfoil data are published at infinite aspect ratio. Picking figures
off the graphs without some additional work can lead to misleading results.
Is there a danger here of mixing Lift and Drag Coefficients with actual Lift
and Drag? Bill G says: " To operate them below that optimum angle of attack
would indeed generate less lift, ... " and George Schroedter says: "When you
decrease the decalage, the angle of attack is decreased. This, in turn,
reduces wing lift, which decreases drag. QED."
In both of these cases it is the Lift Coefficient that is reduced. Normally
the aeroplane would increase speed to still keep the same Lift.
There are a lot of little things that could be argued here but I am painting
with a broad brush just to make the point.
John Barker - England
Historical Notes on Notes
Notes on notes. I knew Roul Hoffman very well probably by trading and
working at Wally's (Simmers) hobby shop in which he ran up front and
the fact that I was one of the few customers that could converse in
Hungarian with him. He gave me an autographed copy of his book. It has
a Hungarian note before his signature. "Homeboy you made it."
ZEEK, Roger Grigsby I was there too in '49. Remember what color Lew's
Zeek was? Roger Coleman if Ray's Models is Ray Acord then why not Air-O
instead of over labeled Premium? WOW 350 s.I. with a Dooling .29!! Yes
the Gas Champion at the World Champs with Cumulus wing and a diamond
fuselage I remember it well. I worked for Carl and on the Cumulus in
1950. The Cumulus came from C.O. Wrights "Hatchet" I have the fuselage
right here. Not to take away from Goldberg but the Zipper is from the
Anderson Pylon. The Viking is from the Ephermis. Of course Carl was a
genius but much of his genius was in developing and marketing other's
ideas. I did say develop. That in itself is a great virtue.
Lift Drag Discussion
Some years ago, Jean Wantzenriether did an analysis of airfoils (in Vol
Libre ) for the then new vertical climb Wakefields. He was surprised
that instead of the slim low camber expected for this development, the
new ships used practically the same profile with its 6% mean camber. It
was speculated that the higher speeds would require an airfoil of the
former type but this was not so.
So these new ships were still using the lift of the wing in addition of
the thrust of the prop to climb fast and high as can be seen at any
local, national or international contest As a corollary, Tony Mathews
told me in Sazena in 97 that some research and turned up that the best
climb duration for maximum altitude and performance was 20 SECONDS!!!.
Perhaps he could expand on this information.
Are power models using lift of the wing on the climb? Some years ago,
it was said that power model's wing came off in the climb and the ship
accelerated markedly immediately. Yes, there is the profile drag of
the wing but is that all??? Do power models really climb VERTICALLY?
Just a few degrees off spoils any equation mooted, surely? And then the
wing must be contributing some lift and its associated drag, mon vieux.
Getting Hold of Verbitsky
I need to get hold of Eugene to order two airplanes. Anyone have his
email address or a method to contact him?
I thought that I had posted the contest announcement on SEM in
November - I just got an inquiry from Brian VanNest who said he hadn`t
heard anything. So, here goes.
SCAT Desert Challenge
Saturday January 8th Gardner Field - - Taft
five flights starting at 10:00 - - no rounds
Three categories, Open Glider, Rubber, and Power.
There will be the traditional bonfire, whether or not Peter Allnutt is
Bring a grill and your dinner, and drinks.
That's about it.