prop speed; when does it create drag?

[Del Rykert]

Correct. Many variables to consider. The speed of the model and if the rpm
you are it still causing thrust or turning slower than the speed your plane
is flying through the air. For models it is very hard to get below an rpm
that still isn't producing slight thrust on landing when you have slowed the
model but while flying downlines I find that rpm's in the 1700-1800 on the
ground do become noticeable on my downlines. Just upping the throttle trim
to 2500 makes a significant difference. These are ground rpm figures as I
have never invested in onboard tach. system. Not necessary to do.

     del

----- Original Message ----- 
From: "Wayne Galligan" <wgalligan at goodsonacura.com>
To: <discussion at nsrca.org>
Sent: Wednesday, December 03, 2003 3:57 PM
Subject: prop speed; when does it create drag?


| Great question John.
|
| Is something like an 1800rpm idle slow enough to create drag while
landing?
| I guess would depend several things like actual airspeed, prop size and
| pitch # of blades, blade width.
|
| WG
|
| ----- Original Message ----- 
| From: "John Ferrell" <johnferrell at earthlink.net>
| To: <discussion at nsrca.org>
| Sent: Wednesday, December 03, 2003 5:39 PM
| Subject: Re: Winter / Focus / Fuel/Electric.
|
|
| > As I am sure you are aware, full scale pilots have been taught for many
| > years that a windmilling prop creates more drag that a stopped prop.
| >
| > How do you determine what rpm generates the most drag?
| >
| > John Ferrell
| > 6241 Phillippi Rd
| > Julian NC 27283
| > Phone: (336)685-9606
| > johnferrell at earthlink.net
| > http://home.sprintmail.com/~johnferrell/dixiecompetitionproducts/
| > NSRCA 479 AMA 4190  W8CCW
| > "My Competition is Not My Enemy"
| >
| >
| > ----- Original Message ----- 
| > From: "Doug Cronkhite" <seefo at san.rr.com>
| > To: <discussion at nsrca.org>
| > Sent: Wednesday, December 03, 2003 4:28 PM
| > Subject: RE: Winter / Focus / Fuel/Electric.
| >
| >
| > >
| > > Well.. you fix that by setting a good idle speed before you take off.
| You
| > > never let the motor stop in flight for a few reasons.. 1) as you
| > > described, it looks weird.. 2) a stopped prop is not the best solution
| for
| > > downline breaking.. 3) the start/stop is hard on the gears..
| > >
| > > -Doug
| >
| >
| > =====================================
| > # To be removed from this list, send a message to
| > # discussion-request at nsrca.org
| > # and put leave discussion on the first line of the body.
| > #
| >
| >
|
|
| =====================================
| # To be removed from this list, send a message to
| # discussion-request at nsrca.org
| # and put leave discussion on the first line of the body.
| #
|


=====================================
# To be removed from this list, send a message to 
# discussion-request at nsrca.org
# and put leave discussion on the first line of the body.
#