Someone please explain 'Slipping' for me...
 

I remember my uncle talking about when he flew his experimental plane how he could 'slip' it into just about any size field. I've heard of 'slipping' when final is extremely short..... my understanding is, slipping is essentially bleeding off speed very quickly in order to land.... but how?

I once watched a video of a STOL wing Avid Flyer experimental plane 'slipping it in' and it looked to me like he was basically at a 20-30 degree angle to the runway (similar to a crosswind landing, using rudder to steer straight) but he kept dipping his wing and then leveling them, kinda like a leaf falling from a tree, and then he landed at almost taxi speed. Unfortunately, the only angle they showed him doing this at, was head on, so that's all I got to see.

Is there a way/reason/purpose to doing this in a model? For instance, if I were to have a Cessna, or J-3 or something like that, and I was flying as realistically scale-like as possible, is this something that could be done with an RC plane (I would assume yes) and how would you do it? Like, what are the exact manuevers?

RE: Someone please explain 'Slipping' for me...
 

Here's a really good article.

http://www.airbum.com/articles/ArticleSlips.html

gus

RE: Someone please explain 'Slipping' for me...
 

ive never done it with a R/C im sure you can and im sure you do it the same way. in full scale you throw in some alieron with opposite rudder. they kind of cancel each other out and let u drop the nessicary altitude while siting semi-sideways like in a crosswind landing. its nice to know how to do if your comin in high on a short final. ill have to give it a try next trip to the field. as far as the wing dipping that was just the pilot adjusting as nessicary.

RE: Someone please explain 'Slipping' for me...
 

In real planes, you actually have 2 options to either bleed off speed or altitude. You can slip a plane as BigNick said using cross controls. That is using your wings to deflect or counter the amount of crosswind (the plane will want to turn in the direction of the bank) and keeping your nose lined up to the runway with your rudder. Thats why planes have a maximum demonstrated crosswind capability. Another way to lose altitude is by crabbing. Crabbing is using left/right rudder (depending on the wind direction) and sinking like a stone. You would increase/decrease the amount of rudder you apply while still keeping your forward motion parallel to the runway. At the last moment, you kick the plane back straight and land.

Sorry, I got to babbling. BIGNICK's answer got me thinking real life.

Carl

RE: Someone please explain 'Slipping' for me...
 

Good descriptions.

I've slipped my Cub a few times, but never all the way to landing. It's definitely a relatively difficult maneuver to do with RC.

We had a club member (hasn't been around for a couple years now) who use to slip his clipped wing Cub in so nicely that I loved to watch it. He'd start about a 100 feet above the runway and two or three hundred feet out. He'd enter a slip that appeared to put the plane at about a 45 degree angle to the runway and it would drop at nearly a 45 degree angle. Then he'd ease out of it and set it on the runway perfectly. His roll out would be about 5 feet. :D

It's certainly possible to do, with a LOT of practice.
Dennis-

RE: Someone please explain 'Slipping' for me...
 

Slipping is very tricky with models that have a positive roll couple (typically trainer types). It should be practiced at a safe altitude before attempting it during a landing approach.

RE: Someone please explain 'Slipping' for me...
 

Slipping is a sideways and downward slide of the plane used in full scale planes for cross wind landings and losing altitude on final approach. I taught both of these methods many years ago as a USAF T-37 instructor pilot.

For cross wind landings, after you line up on final approach, the plane will crab unless you compensate. You lower the wing into the wind to stay on course with the runway center line and use rudder to hold the fuselage aligned with the runway. You end up flying final approach and touchdown with the wing banked into the wind, hence the name "wing low approach."

For losing altitude on final approach, and we taught this for a simulated flame out (SFO) pattern, you stood on the rudder and banked steeply with the nose slightly up. The plane would drop rather quickly. It looked radical and student pilots were a little afraid of it at first, but it worked well and everyone got used to flying it. This brings back memories. An instructor always worried about the student passing the SFO on his check ride and the way to flunk was to end up short of the runway. I always told my students to plan on being high-you didn't have to land on the end of the runway, you had the first third for SFOs. I would tell the student, "Listen, kid, you know when you get near the aux field, you're going to get an SFO. You plan on being high and long. Then when you see you are going to make the field, stand on full rudder, pull the nose up a little and wing down. Check pilots love a student who knows how to slip. It shows you know how to handle the airplane." Never had one flunk. But, I have digressed.

With an RC model, you lack 2 things, indicated airspeed and stall warning. Indicated airspeed is what the airspeed indicator says. This is how fast the plane is going through the air mass. We RC pilots "see" ground speed or how fast the plane is moving compared to the ground. Unfortunately for us RC'ers, planes fly on indicated.

Next, we don't get to feel the burble of a stall warning in the seat of our pants. All we notice in RC to tell us of an approaching stall is a sloppiness in the controls.

When we slip, we use a lot of rudder, some elevator and a bank. Normally full rudder and full elevator are snap roll controls. In a full scale, we can watch the indicated airspeed to tell us we are getting down to stall speed and we can feel the shake, burble of an approaching stall. We can them relax some back stick and/or add power.

In an RC plane, especially down near the ground, full rudder and lots of up can get you into a snap condition before you notice it coming. For this reason, you need to try and practive slips at altitude first. You also need to have a good, light, stall resistant plane. The Cub mentioned in an earlier post is a good one. You never want to try with a swept wing or a sharply tapered wing. these wings are very prone to tip stall.

RE: Someone please explain 'Slipping' for me...
 

pilotny, crabbing if flying with your nose pointed to the direction of a cross wind, flying a line across the ground. You crab into the wind to hold the line. It isn't used to descend.

There are 2 kinds of slips. The forward slip is the one mentioned where the pilot stands on the rudder, flying with the fuse at the max angle to the wind giving max drag and using the ailerons to keep you moving toward the runway. You bank the low wing into the wind when doing this one.

Side slipping is the one talked about where you tip the wing into the cross wind, and use the rudder to hold the fuse allignment with the runway and actually can land on the upwind wheel first, or let go of the side slip at the last minute and crab into the wind to hold the allignment, but you better get rid of the crab before you land. Good way to peel a tire off a rim. Seen that many times. ;)

Its a blast to do with models. Some do it better than others.