Mishandling a forward slip
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Mishandling a forward slip
I've recently started my first instructor job, and I have to say, I'm shocked at how poor the knowledge is with students surrounding the forward slip.
I was always taught the purpose of a forward slip is to lose altitude, therefore it defeats the purpose to have power on. So the procedure I learned was power to idle, trim to maintain an airspeed, enter the slip and hold the nose in a constant attitude to maintain that airspeed.
Anyway, based off what I've seen thus far, my question is, can you mishandle a forward slip so poorly that it results in a stall/spin situation?
I was always taught the purpose of a forward slip is to lose altitude, therefore it defeats the purpose to have power on. So the procedure I learned was power to idle, trim to maintain an airspeed, enter the slip and hold the nose in a constant attitude to maintain that airspeed.
Anyway, based off what I've seen thus far, my question is, can you mishandle a forward slip so poorly that it results in a stall/spin situation?
Re: Mishandling a forward slip
The extra drag means you'll want to lower the nose to maintain airspeed.So the procedure I learned was power to idle, trim to maintain an airspeed, enter the slip and hold the nose in a constant attitude to maintain that airspeed.
But note, depending on the location and quantity of your static ports, the ASI will read too low in a slip (instructive to think about why).
Yes you can stall, but since you're using it to descend faster, it's not a huge issue. Lower the nose to recover.
Spins from a slip: From a forward slip it would be very difficult, as long as you're smooth with the rudder on the entry and exit - sudden yaw can make a wing drop.
Over to the experts.
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Re: Mishandling a forward slip
Never seen (or even heard of) one in the last 40 years.can you mishandle a forward slip so poorly that it results in a stall/spin situation?
Slips are good. Skids are bad.
My only advice is to get the nose down in the slip.
Re: Mishandling a forward slip
But if you lower it (even a little bit) the airplane accelerates very quickly. In mine to maintain the constant speed I need to keep the nose failrly high, much higher than a normal approach. I do like to put the nose lower for short moment when recovering from a forward slip, to compensate for the increased angle of attack on recovery.Colonel Sanders wrote: My only advice is to get the nose down in the slip.
So not sure how you do it, unless there is a trick.... or the airplane itself has considerable drag so it won't matter.
Re: Mishandling a forward slip
I don't get this. Said like that it sounds as though your aircraft has less drag during a slip than during coordinated flight.akoch wrote: But if you lower it (even a little bit) the airplane accelerates very quickly. In mine to maintain the constant speed I need to keep the nose failrly high, much higher than a normal approach.
Re: Mishandling a forward slip
Wow. So then I should just use hold those inputs all the time and my asi will increase. Amazingtrampbike wrote:I don't get this. Said like that it sounds as though your aircraft has less drag during a slip than during coordinated flight.akoch wrote: But if you lower it (even a little bit) the airplane accelerates very quickly. In mine to maintain the constant speed I need to keep the nose failrly high, much higher than a normal approach.
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Re: Mishandling a forward slip
Don't joke about this!! People will post mathematical
proofs, and invent a perpetual motion machine, and that
will be it for Alberta. No more oil patch. Are you really
ready to take responsibility for that?
proofs, and invent a perpetual motion machine, and that
will be it for Alberta. No more oil patch. Are you really
ready to take responsibility for that?
Re: Mishandling a forward slip
Though a forward slip has the control inputs which tend toward a spin entry, in is uncommon for a forward slip to be flown at speeds so slow as to promote a stall. It could be done, but it kinda defeats the reason for being in the forward slip to begin with!
If you are slipping to loose altitude, about the last thing you're going to do is to reduce speed in an attempt to reduce the sink rate! You'll recover the slip first! Now, if you add a turn into that forward slip, so it's not forward anymore, things can change dramatically, and your chances of a spin entry go way up. It's not that you cannot do it, but much more skill and caution are needed....
If you are slipping to loose altitude, about the last thing you're going to do is to reduce speed in an attempt to reduce the sink rate! You'll recover the slip first! Now, if you add a turn into that forward slip, so it's not forward anymore, things can change dramatically, and your chances of a spin entry go way up. It's not that you cannot do it, but much more skill and caution are needed....
Re: Mishandling a forward slip
Too much nonsense in that last post. A slip is quite anti-spin. A skid in quite different though.
Re: Mishandling a forward slip
Yep, the engine really is just there in case you don't like to fly uncoordinated.Rookie50 wrote:Wow. So then I should just use hold those inputs all the time and my asi will increase. Amazingtrampbike wrote:I don't get this. Said like that it sounds as though your aircraft has less drag during a slip than during coordinated flight.akoch wrote: But if you lower it (even a little bit) the airplane accelerates very quickly. In mine to maintain the constant speed I need to keep the nose failrly high, much higher than a normal approach.
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Re: Mishandling a forward slip
The usual problem is people don't know what a slip is and skid the airplane instead. Technically the airplane is probably not slipping when someone gets into trouble with a stall/spin, but the pilot probably thinks he is. I suspect many pilots have gotten themselves into this bit of trouble, soiled themselves, and then erroneusly fear slips from that point on, when they really should be fearing skids. I also suspect that there are enough of these people that have gotten into the flight training establishment in this country (and to be fair, other countries as well, there's a lot of American slipophobes that I've encountered) to form a strong movement against slip training and are contributing to the overall pilot population lacking the ability to do it.Colonel Sanders wrote:Never seen (or even heard of) one in the last 40 years.can you mishandle a forward slip so poorly that it results in a stall/spin situation?
Slips are good. Skids are bad.
My only advice is to get the nose down in the slip.
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To slip the mighty 172, I tilt the wings left and step on the right rudder pedal to keep it from drifting or turning left, that basically points the left wing a bit toward where I'm trying to get the plane to go. As was mentioned, the power is off because I was trying to decend, most likely to land. In the slip I can basically still control the drift left or right and I'm trying to lose height without diving.
The speed doesn't seem too difficult to control, I want to be going about the same forward speed as I would any other time I'm approaching to land. I probably tend to cause the plane to go very slightly faster because I'm trying to decend and might push the yoke slightly, I usually have the plane mostly trimmed for approach before I start to slip.
Once I get the plane near the spot I want to be on approach and I want to be done slipping, I just reduce the pressures on the controls and let the plane straighten out, as it gets near to straight, I start to add what ever control imputs I need to make it do the next thing I want it to. If I was paying enough attention to everything the plane is decending toward the threshold in a line straight down the center line of the runway at my desired approach speed and the numbers are staying in the same spot on the windscreen and getting larger.
I might be doing it all wrong. Slips seem kind of easy and very natural.
The speed doesn't seem too difficult to control, I want to be going about the same forward speed as I would any other time I'm approaching to land. I probably tend to cause the plane to go very slightly faster because I'm trying to decend and might push the yoke slightly, I usually have the plane mostly trimmed for approach before I start to slip.
Once I get the plane near the spot I want to be on approach and I want to be done slipping, I just reduce the pressures on the controls and let the plane straighten out, as it gets near to straight, I start to add what ever control imputs I need to make it do the next thing I want it to. If I was paying enough attention to everything the plane is decending toward the threshold in a line straight down the center line of the runway at my desired approach speed and the numbers are staying in the same spot on the windscreen and getting larger.
I might be doing it all wrong. Slips seem kind of easy and very natural.
Re: Mishandling a forward slip
It's an interesting subject.
Goes back to the FTU taught fear of a steep turn in the circuit, which in a base to final turn where the wind is behind you, unconsciously leads to the temptation to apply too much inside rudder at a low airspeed, to avoid overshooting the centerline.
Dangerous, much more than a coordinated steep turn IMO. I think this is a weakness of FTU's, to properly teach coordinated turns and use them in the circuit, certainly to 30 degrees anyway. If the nose is relaxed a little, allowed to drop, steeper turns are very safe as well.
Some of the training I received by some folks working with confined and terrain airstrips, all turns are 45's.
I am not sure if this is completely accurate, but I would think a descending turn at low power, at least in any cessna, should need almost no inside rudder, and should be safer this way. Correct?
Goes back to the FTU taught fear of a steep turn in the circuit, which in a base to final turn where the wind is behind you, unconsciously leads to the temptation to apply too much inside rudder at a low airspeed, to avoid overshooting the centerline.
Dangerous, much more than a coordinated steep turn IMO. I think this is a weakness of FTU's, to properly teach coordinated turns and use them in the circuit, certainly to 30 degrees anyway. If the nose is relaxed a little, allowed to drop, steeper turns are very safe as well.
Some of the training I received by some folks working with confined and terrain airstrips, all turns are 45's.
I am not sure if this is completely accurate, but I would think a descending turn at low power, at least in any cessna, should need almost no inside rudder, and should be safer this way. Correct?
Re: Mishandling a forward slip
OK, then what is the reason I need to keep the nose up to prevent the airspeed from increasing in the slip? This is the fact of life: with the nose in the same attitude it accelerates, with the nose lower than the stabilized approach (as CS suggested) it accelerates quickly. Keeping the nose up it slips happily and effectively.trampbike wrote:I don't get this. Said like that it sounds as though your aircraft has less drag during a slip than during coordinated flight.akoch wrote: But if you lower it (even a little bit) the airplane accelerates very quickly. In mine to maintain the constant speed I need to keep the nose failrly high, much higher than a normal approach.
To prevent point out in the wrong direction I'll say that the static port is integrated with the pitot port, and has minimal ASI error in the slip.
Last edited by akoch on Sun Mar 31, 2013 1:15 pm, edited 1 time in total.
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Re: Mishandling a forward slip
My first guess would be limited rudder authority.what is the reason I need to keep the nose up to prevent the airspeed from increasing in the slip?
Second guess is the usual combination of plate techtonics and coriolis force.
Re: Mishandling a forward slip
Limited rudder authority - this is always possible. Though it is rigged to the spec. Full rudder slip typically results in about 45-degree nose deflection from the forward trajectory.
Also, to the point of the original question - I intentionally tried to stall in a forward slip (at 4000feet), and pretty much failed. The nose up attitude was ridiculous (something like well over 45 degrees nose up), and it would simply not stall... I guesss in a way it did, the VSI would read 2-3,000 descent rate but the airplane would continue to "fly" like this until the pro-slip or full stick back input is removed.
Also, to the point of the original question - I intentionally tried to stall in a forward slip (at 4000feet), and pretty much failed. The nose up attitude was ridiculous (something like well over 45 degrees nose up), and it would simply not stall... I guesss in a way it did, the VSI would read 2-3,000 descent rate but the airplane would continue to "fly" like this until the pro-slip or full stick back input is removed.
Re: Mishandling a forward slip
What is the definition of a stall? What was your angle of attack? And how much more stalled you would like it to be!? And what other indications of a stall would you expect?akoch wrote:Limited rudder authority - this is always possible. Though it is rigged to the spec. Full rudder slip typically results in about 45-degree nose deflection from the forward trajectory.
Also, to the point of the original question - I intentionally tried to stall in a forward slip (at 4000feet), and pretty much failed. The nose up attitude was ridiculous (something like well over 45 degrees nose up), and it would simply not stall... I guesss in a way it did, the VSI would read 2-3,000 descent rate
Re: Mishandling a forward slip
To me stall is a loss of control (besides the purely aerodynamic abrupt loss of lift effect): both directional, vertical direction, or airspeed or vertical speed.
In that case the airplane continued to be fully controllable in every axis, including the vertical speed that would be linearly modulated by the aft stick pressure. I was not looking for an airplane to maintain the altitude, it was descending and flying as far as I could tell.
In that case the airplane continued to be fully controllable in every axis, including the vertical speed that would be linearly modulated by the aft stick pressure. I was not looking for an airplane to maintain the altitude, it was descending and flying as far as I could tell.
Re: Mishandling a forward slip
I hate to break it to you my friend, but a stall doesn't involve either a loss of control or an abrupt loss of lift.akoch wrote:To me stall is a loss of control (besides the purely aerodynamic abrupt loss of lift effect)
Re: Mishandling a forward slip
How's that? If the aircraft doing exactly what I'm asking it to do - there is no loss of control, aistream separation over wings or control surfaces, how's it is in a stall? Remember, we are not asking the wings to provide much lift in a slip, hence the angle of attack is shallow, despite the optics.
Example - when you attempt to maintain your altitude, and stall the wing(s) - it looses lift and altitude. You lost control of it minimally in vertical axis until you get it back flying again. That's a stall.
Example - when you attempt to maintain your altitude, and stall the wing(s) - it looses lift and altitude. You lost control of it minimally in vertical axis until you get it back flying again. That's a stall.