Ball park over the fence speed calcs
I know when I'm flying too slowly on short final. Nowhere near the stall, but the sink rate gets silly. Can't see how an AoA indicator will better my Seat of Pants approach.
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If no information is given then 1.3 is a good starting point.
And no, seat of the pants won't tell you.
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SSD
Indeed, but given the absence of an AoA indicator, how on earth do you know what IAS 1.3 VS is?
Indeed, but given the absence of an AoA indicator, how on earth do you know what IAS 1.3 VS is?
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I know when I'm flying too slowly on short final. Nowhere near the stall, but the sink rate gets silly. Can't see how an AoA indicator will better my Seat of Pants approach.
This margin should give enough so that you land at or near the stall.
Gs example of 1.64 means that that particular aircraft is so draggy that it requires a bigger margin.
A very slippery aircraft may mean that at 1.3 there is too great a margin.
Last edited by Pull what; 19th Jul 2015 at 20:35.
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So you are saying that you do not know your aircraft stalling speed to be able to times it by 1.3 therefore giving you a minimum approach speed.
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If you are flying that closely by numbers, you ought not to be going into really tight strips.
Your arse should tell you how things are going once you are over the hedge, not your ASI.
Your arse should tell you how things are going once you are over the hedge, not your ASI.
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Your arse should tell you how things are going once you are over the hedge, not your ASI.
There certainly is such a thing as stalling speed SSD, it's just that unlike AoA, it's dependent upon weight, configuration, deceleration rate and g. Stalling AoA is only dependent upon configuration and deceleration rate.
Draggy / slippery is really not the issue here. The aircraft I know with Vref>>1.3Vs tend to have high induced drag, low inertia. In other words, as you roundout and flare, there's a lot of drag acting against not very much momentum. The result is rapid deceleration.
A motorglider is slippery - yes. But also they're heavier than most - probably all - microlights, and with that long slender wing, have very low induced drag. So, the speed bleeds off very gradually, and thus a relatively low approach speed can be appropriate. By comparison, most microlights have low mass, already low approach speeds (remembering that kinetic energy goes with the square of speed, so reducing approach speed to 80% reduces kinetic energy to 64%), and a short fat wing which tends to generate a lot of induced drag at high AoA.
I would guess that the Bristol Freighter was similar to a motorglider - ***** heavy, with a fairly long and efficiently lifting wing. Not slippery however, definitely not slippery !
G
Draggy / slippery is really not the issue here. The aircraft I know with Vref>>1.3Vs tend to have high induced drag, low inertia. In other words, as you roundout and flare, there's a lot of drag acting against not very much momentum. The result is rapid deceleration.
A motorglider is slippery - yes. But also they're heavier than most - probably all - microlights, and with that long slender wing, have very low induced drag. So, the speed bleeds off very gradually, and thus a relatively low approach speed can be appropriate. By comparison, most microlights have low mass, already low approach speeds (remembering that kinetic energy goes with the square of speed, so reducing approach speed to 80% reduces kinetic energy to 64%), and a short fat wing which tends to generate a lot of induced drag at high AoA.
I would guess that the Bristol Freighter was similar to a motorglider - ***** heavy, with a fairly long and efficiently lifting wing. Not slippery however, definitely not slippery !
G
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Genghis - you eloquently point out that there is no such thing as stalling speed for all practical purposes. Sure, a speed at which an aeroplane at a given loading (G and weight) will stall can be calculated if you have all the data, which you don't.
An AoA indicator gives an unequivocal direct simple read-out of how close to the stalling angle you are.
Agree with Mono that the next best thing to an AoA indicator is 'your arse', or more correctly the 'feel' of the aeroplane. If you are familiar with the type, and esepcially if you aerobat it, you will know how the controls feel just before it departs (this assumes you are creeping up to the stalling angle gradually, as one would be on approach; a sudden hard pitch up might put you beyond the stalling angle with no warning signs).
An AoA indicator gives an unequivocal direct simple read-out of how close to the stalling angle you are.
Agree with Mono that the next best thing to an AoA indicator is 'your arse', or more correctly the 'feel' of the aeroplane. If you are familiar with the type, and esepcially if you aerobat it, you will know how the controls feel just before it departs (this assumes you are creeping up to the stalling angle gradually, as one would be on approach; a sudden hard pitch up might put you beyond the stalling angle with no warning signs).
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Sure, a speed at which an aeroplane at a given loading (G and weight) will stall can be calculated if you have all the data, which you don't.
Sure, a speed at which an aeroplane at a given loading (G and weight) will stall can be calculated if you have all the data, which you don't.
Below max weight then you will have to go out and experiment to find out what the stall speed is at lower weights but to be honest why bother on a small aircraft when there is probably only a few knots difference, thereafter you can times it by 1.3 for an approx. approach speed.
An AoA indicator gives an unequivocal direct simple read-out of how close to the stalling angle you are.
The majority of light aircraft stall spin accidents in the circuit happen around the turn on to base leg and final approach or short finals, generally when the workload is high for the low time or out of currency pilot. The reason, because they were not monitoring the airspeed, i.e not looking at the ASI or due to workload not registering what it was telling them.
So lets add another gauge AoA for the same pilot, do you really think this is now going to get anymore attention in the same situation ? an AoA is nothing new they have been around for years since the Navy developed them for carrier landings but unless the pilot has the ability to actually fly and monitor the situation developing around him/her then no amount of instruments are going to help.
Last edited by Above The Clouds; 20th Jul 2015 at 11:33.
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Cows getting bigger
I can't remember the last time I confirmed I was at Vref when "over the fence" on a SEP performance landing.
I can't remember the last time I confirmed I was at Vref when "over the fence" on a SEP performance landing.
couldn't agree more, but the children of the magenta line have found a new toy, an AoA gauge.
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What other data do you want for a light aircraft, the calculated stall speed is given for most light aircraft at max weight, in unaccelerated flight 1g, in a given configuration, clean and with flaps extended, those are the bench marks.
I tend to monitor airspeed, because in a typical year I maybe fly a dozen types, and don't trust myself to get the pitch attitude right when I'm seldom all that familiar with the model. Airspeed, with a little bit of maths, IS a useful guidance method. Most of the time we're also in relatively unaccelerated flight, so wings level stall speed is a simple function of weight.
Also whilst 95%+ of aeroplanes don't have IAOA available, 99%+ of aeroplanes do have IAS. We use what's there. Oh yes, and I'd guess that less than 50% of IAOA systems have been subjected to rigorous flight testing leading to proper guidance and training material on their use.
G
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Genghis the Engineer
Oh yes, and I'd guess that less than 50% of IAOA systems have been subjected to rigorous flight testing leading to proper guidance and training material on their use.
Oh yes, and I'd guess that less than 50% of IAOA systems have been subjected to rigorous flight testing leading to proper guidance and training material on their use.
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I've flown AoA indicators in several types, from C-150 to Piper Cheyenne. It was great in the Cheyenne, as that type is less forgiving of seat of the pants flying - just fly numbers. But lighter aircraft may reward the sensitive butt with good feedback. In any case, letting your eyes go back in to the panel at the critical moments of the final approach probably creates a much greater risk than flying the approach a bit off speed.
This can certainly be a serious situation on some types, which are heavy and draggy, with lots of lift. Cessna floatplane amphibians being an example. You can fly a final approach at about the 1.3Vs, and with the AoA indicating okay, but in a condition that only a lot of power at the bottom is going to fix. The errant pilot has let the plane slow too much to enable a flare from a steep approach on the combination of speed and altitude alone.
This can happen with a poorly set up approach to a short landing area over an obstruction. An unaware pilot will cross the obstruction going down, at a suitable airspeed, but with a rate of descent which is much too great to arrest at the bottom with the aircraft's reserve of energy alone. For these approaches, you either retain the required excess energy as speed all the way down final, or carry lots of power down final (which has the dangers associated with an engine failure - assured crash). Several amphibians I fly have a power off stall speed about 55 MPH. For a power off landing, I'll train a glide speed of 80. You can glide at 65, and the aircraft is quite happy, but when you pull to flare, you'll get an instant stall horn, and no arrest of descent rate - crunch! One of these planes has the newest AoA, which I set up as new. In 80 hours of flying it, I have never referred to it, I'm too busy watching where I'm going out the windshield.
For the GA type aircraft, you have to know the plane, hone your seat of the pants and hand&feet skills and fly them that way first. Magenta lines and instrument readings only when the aircraft is already being well flown!
I know when I'm flying too slowly on short final. Nowhere near the stall, but the sink rate gets silly. Can't see how an AoA indicator will better my Seat of Pants approach.
This can happen with a poorly set up approach to a short landing area over an obstruction. An unaware pilot will cross the obstruction going down, at a suitable airspeed, but with a rate of descent which is much too great to arrest at the bottom with the aircraft's reserve of energy alone. For these approaches, you either retain the required excess energy as speed all the way down final, or carry lots of power down final (which has the dangers associated with an engine failure - assured crash). Several amphibians I fly have a power off stall speed about 55 MPH. For a power off landing, I'll train a glide speed of 80. You can glide at 65, and the aircraft is quite happy, but when you pull to flare, you'll get an instant stall horn, and no arrest of descent rate - crunch! One of these planes has the newest AoA, which I set up as new. In 80 hours of flying it, I have never referred to it, I'm too busy watching where I'm going out the windshield.
For the GA type aircraft, you have to know the plane, hone your seat of the pants and hand&feet skills and fly them that way first. Magenta lines and instrument readings only when the aircraft is already being well flown!
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Quote:
What other data do you want for a light aircraft, the calculated stall speed is given for most light aircraft at max weight, in unaccelerated flight 1g, in a given configuration, clean and with flaps extended, those are the bench marks.
SSD
And then the driver, flying it solo with not much fuel in the tanks, adds 15% for the wife and kids. Could explain all those busted nose wheels!
That does not answer my question, what other data is it you require. As I stated earlier figures in light aircraft AFM's are based on max weight, if you need to find out the stalling speed at lower weights then you have to go and fly the aircraft and stall it.
What other data do you want for a light aircraft, the calculated stall speed is given for most light aircraft at max weight, in unaccelerated flight 1g, in a given configuration, clean and with flaps extended, those are the bench marks.
SSD
And then the driver, flying it solo with not much fuel in the tanks, adds 15% for the wife and kids. Could explain all those busted nose wheels!
Last edited by Above The Clouds; 21st Jul 2015 at 17:57. Reason: spelling
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I'd want an AoA indicator principally for aerobatics, where one can stall at any IAS (or not). But it would be useful to glance at on approach as well.
Someone said of IAS "we use what we have". Crikey, talk about begging the question! What we 'have' can be changed, you know!
Someone said of IAS "we use what we have". Crikey, talk about begging the question! What we 'have' can be changed, you know!
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if you need to find out the stalling speed at lower weights then you have to go and fly the aircraft and stall it.