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Old Mar 19, 2007, 04:11 PM
bobthefish50
United States, OR, Salem
Joined Jul 2006
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Side Slipping A Model Sailplane

I have read that full-scale sailplane pilots use this maneuver.

Do model sailplane pilots? How is it done? Does it require 3-axis control?

Thanks for sharing the information.

Bob
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Old Mar 19, 2007, 05:31 PM
Registered User
Minnetonka, Minnesota, USA
Joined Jan 2005
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Models can slip too. Just roll it one way and appy rudder the other way (cross-controlled). Slipping kicks the plane around a little sideways to the direction of flight, creating a lot of drag. It's a way of slowing it down or steepening the decent of a plane not equipped with flaps or spoilers. If you have either of those control options, use them... they're more effective.

Good rudder authority is required. Longer wing spans are harder to horse around with the rudder, so slipping is relatively less effective with longer wings.

Tim
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Old Mar 19, 2007, 05:46 PM
bobthefish50
United States, OR, Salem
Joined Jul 2006
35 Posts
Thanks, Tim. Do you use any elevator?

Bob
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Old Mar 19, 2007, 06:31 PM
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United States, TX, Lytle
Joined Dec 2006
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You're going to have to do this with a plane with ailerons, rudder and elevator. I don't believe you can do this with one equipped with RES.
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Old Mar 19, 2007, 08:02 PM
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United States, OK, Moore
Joined Jan 2006
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Phoebusflyer is correct, you need 3 axis control. By it's very nature, and the way wings are banked with a RES ship, RES won't do it. As for elevator, it still functions as normal, controlling nose up or down attitude.
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Old Mar 19, 2007, 08:48 PM
bobthefish50
United States, OR, Salem
Joined Jul 2006
35 Posts
My understanding of sideslipping is that the nose is perpendicular to the direction of the aircraft, i.e., the belly of the plane is where the nose should be. Thus the entire fuselage and wing bottoms are creating drag, correct?

If so, I would think that the components of the manuever would be

1) Bank
2) Maximum elevator
3) Rudder in a direction opposite to that of the bank as was noted.

However, what has been reported suggests that the elevator isn't as important as the rudder. Do I understand that correctly?

Thanks.

Bob
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Old Mar 19, 2007, 08:58 PM
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USA, FL, Pensacola
Joined Sep 2004
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I watch full scale gliders weekly and seldom see it used. Though it does have it's time and place, it is not as effective as in power planes, all things being equal. Sailplanes, while having generous wing area, do not provide much side plate area. It is a neat trick, and does help in some situations but as mentioned in previous posts, in our particular applications, spoilers, flaps and their variations work much better. I have tried it pretty often with full house stuff and I have seen no benefit other than looking way cool on scale gliders!
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Old Mar 19, 2007, 09:23 PM
Full Scale Better! UOHHHH!
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United States, TX, Lytle
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Slipping works much better in full scale on the older, more slab sided planes. The newer glass ships benefit from it much less. I would think a full house 3 or 4 meter ship would see little benefit from it especially some of the newer, low profile ships.
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Old Mar 19, 2007, 09:28 PM
dlobbster
Snohomish Washington
Joined Oct 2006
64 Posts
Technically there are two different kinds of slips. A forward slip is used
for loseing altitude fast and a side slip is used for landing in a crosswind.
In a forward slip the fuselage is crabbed slightly diagonal to the runway
with one wing low and the rudder used to keep the aircraft heading
straight down the runway. In a side slip the wing on the crosswind side
is lowered just enough to offset the force of the crosswind and rudder
is used to keep the fuselage parallel with the runway. Haveing said all
that, I agree that flaps or spoilers are easier and more effective on an
RC sailplane.
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Old Mar 19, 2007, 09:34 PM
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United States, TX, Weatherford
Joined Nov 2002
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If you do try it, and have ample side area to make it work, you will need some down elevator to keep the airspeed up. Any way you add drag slows the ship down. A 2-33 or a Blanik will benefit nicely from a slip. My PIK or Allen's Phoebus won't be nearly as draggy. The pencil thin fuselages of most of the F3B and F3J models would almost be useless as drag devices... just my take on it.

Jack
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Old Mar 21, 2007, 03:47 PM
bobthefish50
United States, OR, Salem
Joined Jul 2006
35 Posts
Thanks, guys.

For a great story about sideslipping a 767 that had run out of fuel, check
http://www.casa.gov.au/fsa/2003/jul/22-27.pdf.

Bob
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Old Mar 21, 2007, 05:12 PM
Permanently Banned
Dallas TX
Joined Oct 2004
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Side area

Quote:
Originally Posted by schrederman
If you do try it, and have ample side area to make it work, you will need some down elevator to keep the airspeed up. Any way you add drag slows the ship down. A 2-33 or a Blanik will benefit nicely from a slip. My PIK or Allen's Phoebus won't be nearly as draggy. The pencil thin fuselages of most of the F3B and F3J models would almost be useless as drag devices... just my take on it.

Jack
I was more concerned with anti slip! Trying to nail a spot with small yaw angles using a regular Legionair was difficult; whereas, using the Shuttle (Legionair) fuse with it's 'billboard' sides made it a lot easier.

To get into small feild construction sites that were supplied/serviced by a Cessna 175; my T'Craft with repair parts, had to use the forward slip frequently. Hard aileron, rudder to kill off 55 mph aproach speed, then settle down onto 3 points (actually the tailwheel would be rolling first). Take off was usually 3 points also (rough feild automatic liftoff at 45 mph).
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Old Mar 21, 2007, 06:59 PM
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David Forbes's Avatar
United States, FL, Gainesville
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Bob,
That link was fascinating, thanks for sharing.
Dave
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Old Mar 21, 2007, 08:39 PM
Questio scientia
equest's Avatar
Texas
Joined Apr 2003
216 Posts
Take a look at this. Slide slipping to the extreme. A good visual representation to those that do not understand what it looks like.

Equest
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Old Mar 21, 2007, 09:14 PM
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