Forward Slips

TheHub · Post by **TheHub** » Wed Mar 03, 2004 11:44 am

Anybody ever have a bad experience using forwards slips with floats???
An old instructor advised me not to perform the maneuver as he had a 'complete loss of lift' when coming over the trees for a landing. He said the plane felt like it stalled instantaneously and started to fall towards the water. This was in a cub on floats.
Before he told me the story, I had been using that method to get down over a high set of trees along the shoreline quite frequently without any problems.
Do you guys think the floats could have caused a large enough disruption in airflow to cause a tail stall, or was it just the downdraft often found along the treeline???
Obviously I am still learning, so any input would help me out.
Thanks!

skywagon · Post by **skywagon** » Wed Mar 03, 2004 4:37 pm

I have done it in a PA-12 lots in the past and never had a problem.

Intentional Left Bank · Wed Mar 03, 2004 11:12 pm

The old guy that trained me told me that learning to fly floats can at times be like walking around on a table while blindfolded: you don't know how close you are to the edge until you step off of it.

I really can't say whether or not slips can bite you in a float plane, as I never flew one that didn't have flaps. I've seen guys on a couple of occasions hit the water pretty hard in a Beaver due to (what they attributed to) tail stall caused by excess flap disrupting airflow over the tail. Seeing that was enough to teach me not to get too aggressive in my short-lake landings.

Nowadays when I go into a tight spot, I just put 'er in high idle and flatten the blade angle to 11 degrees.

flybynight · Post by **flybynight** » Thu Mar 04, 2004 2:11 am

I've side slipped alot with floats on and never had a problem, what your instructor probably incountered was wind shear over the trees, i suggest that you go up to a safe altitude and practice with floats on see what kind of reaction you get out of the type your flying.

cheers and have fun

4green · Post by **4green** » Thu Mar 04, 2004 7:56 am

i cut my teeth on a little puddle jumper sans flaps, 'slips' are about as apt to bite you as 'turning'. i have a hard time with the fact that your instructor's plane "stalled instantaneously" and plummetted to the earth, as mentioned i'd suspect shear across the treeline which you have to always take into account when doing those chop'n'drops.

with anything bigger than a 185 the issue becomes arresting the descent rate. if you've thrown yourself at the water in good fashion with full flaps and a monster slip, it's quite possible to rotate the nose while still at 50' over the water and not catch it in time.

i'm with ILB, few things are as satisfying as a handful of discing

Cat Driver · Post by **Cat Driver** » Sat Mar 06, 2004 6:53 pm

The Hub :

The "old" instructor gave you bad advice.

Slipping float planes is normal, especially J3's.

Cat.

Driving Rain · Post by **Driving Rain** » Sat Mar 06, 2004 11:56 pm

I agree with the Cat side slips are very usefull even with some flap deployed. The 215 a large airplane loves to slip even with 15 degrees of flap. The slip has rescued me from some rather bad approaches at times. Just remember to keep your airspeed up a little bit to avoid stall and level your wings at least 150 ft above the surface.

dont_snag_it · Post by **dont_snag_it** » Mon Mar 08, 2004 7:40 am

Cat Driver · Post by **Cat Driver** » Mon Mar 08, 2004 10:53 am

Loadfactor2 :

What is your point?

Or maybe you want some advice on how to perform a slip?

It is basic flying is it not?

Cat

justplanecrazy · Post by **justplanecrazy** » Mon Mar 08, 2004 7:42 pm

I think loadfactor might be hitting on the fact that your IAS will be slightly out of wack in a slip.

Your airflow won't enter the pitot tube straight on so it'll show an IAS lower than your IAS when flying straight. This won't decrease the saftey factor though. It'll actually make the ignorant pilot fly faster than neccessary, because of a lower than normal IAS vs. TAS

The Champ won't get into the good fishing spots without the slip... haven't heard any wacky stall charachteristics due to this. Cessna does warn about doing slips with full flaps but doesn't give any reasoning.

TheHub, how many hours did your instructor have?

Cat Driver · Post by **Cat Driver** » Mon Mar 08, 2004 9:41 pm

Who gives a shit what the airspeed reads when you are slipping to lose height on a landing approach...why would anyone be looking at the airspeed at that point????

If a pilot does not have the smarts to perform a side slip and recover back to normal flight at the same airspeed they entered the slip there is something terribly wrong with their flying skills.

Cat

ahramin · Post by **ahramin** » Mon Mar 08, 2004 10:33 pm

Ha.

I have met instructors who wouldn't take a C150 up into a steady 15 knot crosswind.

I am sure that you will find that anyone who lacks the skill to perform a good sideslip or any other normal maneuver will hide behind the safety card. "I am safer than you because i don't do sideslips."

Have a look at the air cadets gliding at YCD this spring. They are not allowed to do sideslips below 300 feet because they might not recover in time. The fact that they would pass someone who cannot recover from a sideslip in less than three hundred feet is not a safety issue, but cowboys who do slips are.

ahramin

twotter · Post by **twotter** » Tue Mar 09, 2004 1:45 am

Actually your indicated airspeed could be higher or lower than your TAS depending on where your static ports are.

The best way to do it is to maintain your "ATTITUDE" just like you would in the event that you had an airspeed indicator failure. As Cat says, at that time in a light airplane who's looking at the airspeed. Know your airplane and fly the correct attitude and you won't get into trouble.

As for getting into trouble, the only thing I've seen is that some airplanes will tend to drop the nose when slipping with flaps.. Just be aware of it and prepared for it. Try it on a good day at altitude when you are empty and see what it does. It ain't rocket science, after all it's only an airplane and if all of us can fly them, it can't be too hard...

Maverick · Post by **Maverick** » Tue Mar 09, 2004 10:22 am

ahramin,

That 300ft rule is just a guideline, its not set in stone. You can slip right down to the ground if you wanted to. I've done it lots of times. If you need to get down, you need to get down. Just don't go down too much, because you won't be able to get back up.

Ah....I want to go gliding again....To bad there are no mountains where I live...Oh well

4green · Post by **4green** » Tue Mar 09, 2004 10:49 am

You can slip right down to the ground if you wanted to.

three point landings in the sgs means it's time for a runway change

TheHub · Post by **TheHub** » Tue Mar 09, 2004 5:32 pm

justplanecrazy,

he has thousands of hours, mostly float time, but quite a bit of ski time and wheel time as well.
Thanks to everyone for the input...I'll continue to use florward slips.
I find flying floats to be the most enjoyable part of aviation, but also the part that can get you into trouble the fastest!
Happy flying and hopefully I'll see some of you on the lakes when the ice comes out...
Cheers

justplanecrazy · Post by **justplanecrazy** » Tue Mar 09, 2004 5:40 pm

ahramin wrote:Ha.
Have a look at the air cadets gliding at YCD this spring. They are not allowed to do sideslips below 300 feet because they might not recover in time. The fact that they would pass someone who cannot recover from a sideslip in less than three hundred feet is not a safety issue, but cowboys who do slips are.
ahramin

Do you mean Forward Slip?? I haven't ever done a sideslip over 300 feet. I always crabbed into the wind and then on short final, sideslipped right to the ground to maintain the center line. Do they tell them not to drop a wing when landing in a crosswind??? If they drop a wing, and fly straight, they are side slipping.

twotter wrote: The best way to do it is to maintain your "ATTITUDE" just like you would in the event that you had an airspeed indicator failure. As Cat says, at that time in a light airplane who's looking at the airspeed. Know your airplane and fly the correct attitude and you won't get into trouble.

I think what you mean is hold the proper forward slip attitude, don't maintain your attitude. Haven't heard of a plane where you haven't had to change your "Attitude" once you turn it sideways to the airflow. The whole point of a forward slip is to create a lot more drag by turning the plane sideways so you can go into a more nose down attitude without gaining more airspeed. This is probably what you meant but I thought I'd be sure.

As for airspeed, when students first do a forward slip they tend to do it without lowering the nose and almost always bleed the airspeed off until the rollercoaster point. Airspeed is the way that they can determine the proper attitude. Look at the airspeed once you first turn sideways and don't let it decrease or increase. Once you know this attitude... like Cat says... the airspeed shouldn't be important. Experienced pilots don't need it, but beginners do, especially when there is no-one to ask if they are doing it right.

ahramin · Post by **ahramin** » Tue Mar 09, 2004 8:39 pm

They said sideslip, but you are right. They meant forward slips. The edicts do not have to make any sense, as long as everyone understands that the edicts come from the boss and he or she is the boss because he or she sends edicts.

ahramin

justplanecrazy · Post by **justplanecrazy** » Wed Mar 10, 2004 6:26 pm

TheHub wrote:justplanecrazy,

he has thousands of hours, mostly float time, but quite a bit of ski time and wheel time as well.
Thanks to everyone for the input...I'll continue to use florward slips.
I find flying floats to be the most enjoyable part of aviation, but also the part that can get you into trouble the fastest!
Happy flying and hopefully I'll see some of you on the lakes when the ice comes out...
Cheers

hahahahha...

He probably didn't like getting pressed against the window while holding his coffee then.

I totally agree with you about the danger/pleasure reference. I think that
Intentional Left Bank had an awesome quote from "the old guy"

The old guy that trained me told me that learning to fly floats can at times be like walking around on a table while blindfolded: you don't know how close you are to the edge until you step off of it.

I'm kind of concerned about the other part of his post though:

I've seen guys on a couple of occasions hit the water pretty hard in a Beaver due to (what they attributed to) tail stall caused by excess flap disrupting airflow over the tail. Seeing that was enough to teach me not to get too aggressive in my short-lake landings.

I think that this is definately not caused by a tail stall. A tail stall would cause an abrupt pitch forward and stick the front of the floats into the water. If this is happend, they wouldn't have a simple "hard" landing, rather they'd have a belly up duck!!

4green probably hit the real problem for the bad landings:

with anything bigger than a 185 the issue becomes arresting the descent rate. if you've thrown yourself at the water in good fashion with full flaps and a monster slip, it's quite possible to rotate the nose while still at 50' over the water and not catch it in time.

Don't be afraid to be aggressive in a plane. Just know and anticipate the effects that that aggressive action will have on the plane. Look ahead at what is going to happen 50' later. Being overly cautious or afraid of what might happen, is often the cause of accidents.

twotter · Post by **twotter** » Wed Mar 10, 2004 7:31 pm

By attitude, I mean the appropriate pitch attitude to maintain sufficient airspeed so you do not stall..

As for the people sideslipping a 2-33 into YCD, well, I started doing that in 75 and back then we could do what was necessary to get it down.. I guess they trained better pilots back then...

justplanecrazy · Post by **justplanecrazy** » Thu Mar 11, 2004 5:43 pm

twotter wrote:By attitude, I mean the appropriate pitch attitude to maintain sufficient airspeed so you do not stall..

As for the people sideslipping a 2-33 into YCD, well, I started doing that in 75 and back then we could do what was necessary to get it down.. I guess they trained better pilots back then...

To know what attitude you can hold and not stall you first have to know what attitude produces what airspeed

Cat Driver · Post by **Cat Driver** » Thu Mar 11, 2004 6:40 pm

So what is your point???????

justplanecrazy · Post by **justplanecrazy** » Fri Mar 12, 2004 6:15 pm

My point Cat???

Just trying to clear up the fact that you should be looking at your airspeed until you know that specific plane.

I can jump in a Champ and point the thing straight down in a slip and it won't gain much speed. If I do the same thing in a Twin Otter with no flaps (I haven't had the privelege but I imagine if I asked someone I'm right on this one.) I'd end up ripping the wings off.

There is no such thing as an "Attitude" that can be taught to a student. How do you explain to a student how to do a slip??? Or cruise??? You know the whole 3 finger cruise is only a ballpark. It depends on the seat height, the students height, the dash height, cruise speed etc. Sometimes its no fingers sometimes its a hand and three. So how do you teach a student to tell where the horizon should be lined up for them? Well you get them to hold the altitude constant and then take note as to where the horizon is to produce that result.

Now how about those illusions where approaching an upsloping horizon our airspeed suddenly bleeds and our altitude increases. Cover up these gauges and plug your ears and even seasoned pilots will find themselves slightly climbing.

In a slip it is even more difficult to determine your angles. Often you are using a slip to provide a steep descent among terrain. There is very little reference clues to tell you of your attitude.

Cat Driver wrote: Who gives a shit what the airspeed reads when you are slipping to lose height on a landing approach...why would anyone be looking at the airspeed at that point????

twotter wrote: The best way to do it is to maintain your "ATTITUDE" just like you would in the event that you had an airspeed indicator failure. As Cat says, at that time in a light airplane who's looking at the airspeed. Know your airplane and fly the correct attitude and you won't get into trouble.

So to completely contradict you and Twotter a student needs to know their airspeed. You can't be sure of your Attitude unless you know your Airspeed. They go hand in hand. Reference clues will always change but Airspeed will remain the same. The less experience you have in that plane, in that area and especially in the air, the more important it is to know what airspeed your attitude is producing. To teach a student simply by attitude will certainly cause a dangerous situation. It is important to tell him/her the faulty airspeed readings in a slip and then how to use those faulty readings to ensure that they are not approaching a stall or that they won't be going 160kts as they start their flare.

When you are experienced as I'm sure you two are, you start to forget how important this dial was way back when.

So to recap and correct an error that Twatter pointed out on one of my earlier posts. Your airspeed in a slip will increase or decrease depending on where the static port is and which side you are slipping to. First the pitot tube, regardless of the slip will have an angled flow coming into it. This alone would decrease your IAS. Now the static port will either counter this effect or increase it. If the port is on the side you're slipping to, it will have airflow into it. This will cause a higher than normal pressure in the static port and decrease your airspeed even more. This will, lower your airspeed significantly. Slipping away from the static port will have a minimal effect but will cause a slightly lower pressure in the static port than normal. This will counter the decreased pitot pressure and equalize or maybe even increase your airspeed.

So for those of you wondering how to teach what airspeed to use, get them to monitor their airspeed before they enter the slip. As soon as they enter it, make reference to what it reads. This reading is what the plane will now read for the previous Airspeed. Confusing but just take this example. I'm slowing for an approach. As I reach 70kts, I enter a forward slip. I immediately check my airspeed and notice that its now reading 60kts. So a 60kt reading tells me that I'm going 70kts. I might normally be concerned at how close my IAS is to the stall speed but I know that that IAS is actually 10kts too low. I can continue my aproach checking to make sure my attitude is holding the 60kts and I know that when I straighten out and flare, I will be flaring at 70kts with enough safety factor but not too much speed to be able to land in time.

Cat Driver · Post by **Cat Driver** » Fri Mar 12, 2004 7:09 pm

Justplanecrazy....

You obviously mean well and in a way most of what you post is sort of correct.

However I think you are making things to complex for a relatively simple thing like attitudes and movements and the side slip thing is just another attitude, no more complex to understand than any other.

As I have previously mentioned most pilots are airspeed chasers and can not maintain a constant attitude......

I will occasionaly glance at the airspeed when slipping but only briefly to confirm its reading, I rely on the visual clues outside the airplane and the sound and feel remains the same if I wish to hold the slipping attitude..

By the way a Twin Otter has lots of rudder effectiveness for slipping...but they also have a very good rate ofdecent with the power just above bata. Actually its easier to fly than a champ.

To bad we couldnt fly for an hour or so together and do some one minute alternating left and right hand circuits never going above two hundred feet just to sort of get the cob webs out of our flying skills.

That is the best method that I know of for teaching pilots to look outside and fly attitudes without staring at the instrument panel to confirm what you aready can see outside.

Anyhow some day you may change your methods of training and make things far more simple for your self...

The easiest person to teach the basics to is someone who has never flown before, I find the hardest ones to teach advanced flying skills to are instructors.....

And I believe the problem comes from the poor instruction they received from their instructors that did not understand how to teach the basics....

Just my own findings from what I have experienced when trying to upgrade the skills of those who come to me for training.

So my suggestion is keep things as simple as possible and for Gods sake don't teach them to chase the airspeed.

.

4green · Post by **4green** » Fri Mar 12, 2004 11:37 pm

i think i learned the most about driving planes in a glider with the instruments covered and no yaw string. eyeball the altitude, listen for the airspeed and turn coordination.

juice boxes in the spoilers for good measure