G loading ?
damn, rolling G..
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positve G at top of the loop. add in rolling G and more backstick at you roll past 90 deg, one wing stalls, and your suddenly upright a lot faster than you expected.
oh, in a Robin.
oh, in a Robin.
Last edited by Ultralights; 2nd Jan 2013 at 12:02.
4G at the TOP of a loop???
I must be doing it rong!
Let me watch you doing a stall turn:
I must be doing it rong!
Let me watch you doing a stall turn:
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actually over the top im not exactly sure what the G loading is, normal loop in at 4 G, competition loop, aim for 5 with relaxing the stick over the top. so probably -1 G over the top of a competition loop. but roll off the top sometimes is helped by the rolling G added in the roll when one wing stalls.
as for hammerheads, "stall turns" i have a few vids to edit yet. fallen out of a few early ones into a nice tailslides. still cant figure out why they are called stall turns.
as for hammerheads, "stall turns" i have a few vids to edit yet. fallen out of a few early ones into a nice tailslides. still cant figure out why they are called stall turns.
Last edited by Ultralights; 2nd Jan 2013 at 08:49.
Manoeuvre/turb speed = stall speed x the square root of the limit load factor.
Would you care to elaborate on this "rule".
Firstly, manoeuvre speed (if you mean max manoeuvre speed) Va might be a particular regulatory minimum (~ 1.9Vs, 1G power off, or Vs1 times the square root of the limit load factor) , but to suggest that this should be the turbulence penetration speed is a highly questionable "recommendation".
Indeed, for years I have flown aircraft with a recommended turbulence speed fixed in a narrow IAS/MNo band, regardless of weight, with a proviso that you can safely reduce the IAS when below max landing weight by about 50 kt. --- as the manufacturer says:"To reduce stress on the airframe".
To fly at the certified maximum manoeuver speed in turbulence can easily lead you into breaking something, Va is designed for /demonstrated in smooth air with smooth application of control with no rapid control reversal. To fly at that speed in turbulence can seriously cause a problem that will ruin your whole day.
Another somewhat lighter aircraft that I fly has a maximum turbulence speed well below Va.
The turbulence speed for your aircraft is what the AFM says it is, and at lighter weight even slow from that, if control is adequate, and you want to reduce further the loads on the airframe.
To say that higher speeds at higher weights does not increase the stresses in turbulence is just (engineering-wise) loopy. And does not make any sense for practical flying purposes.
Tootle pip!!
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Really 4 G in a Robin at the TOP of a loop, what is powering it ??????? a gas turbine.
In my T28 with 1400 HP I enter a loop at 4 G 230 Knots and arrive at the top at 110 if I get it right and just G positive , I must be doing something wrong, Maybe I need new knowledge on this Aeros stuff, but I certainly run out of energy at thetop of the loop, funny the Extra 300 I fly does the same thing, must be technique.
In my T28 with 1400 HP I enter a loop at 4 G 230 Knots and arrive at the top at 110 if I get it right and just G positive , I must be doing something wrong, Maybe I need new knowledge on this Aeros stuff, but I certainly run out of energy at thetop of the loop, funny the Extra 300 I fly does the same thing, must be technique.
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im not exactly sure of the G over the top,i have edited my initial post to reflect that, it was meant to illustrate my point of increased G load in a manoeuvre, combined with the added Rolling G combined to create a stall situation. G over the top isnt much, im not looking at the G meter then, im looking at the horizon and line feature but i have felt the g stall during the roll off the top numerous times. so i am pretty certain the added rolling G factor while rolling off the top is whats generating the stall of one wing. every other stall in the loop is simply exceeding critical AOA.
all on the topic of G loading.. but will consult my instructor for a more in depth explanation.
all on the topic of G loading.. but will consult my instructor for a more in depth explanation.
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LeadSled - I'm not sure about a 'rule', but the principle is sane - according to Mr Newton, F=ma (and therefore a = F/m)
So as M gets bigger, the same force will produce a smaller A (or G loading) - the aircraft is somewhat less sensitive to gusts. Last time I checked, the POH for the oh-so-common Cessna 172 listed two Va values, one for MGW, and one for very light weight. I don't believe there is a specific turbulence penetration speed, Vno around 120something, Va 104(?), so Va is/was generally taken as a safe turbulence speed, at least as I was taught. (Caveat I've not flown a 172 for ages, hence being a bit vague)
Also of course as the a/c gets heavier, there's a practical limit to how much acceleration that the wing can produce without stalling - not that that's a particularly useful method of turbulence avoidance, and all of this is ignoring any secondary effects, other than immediate acceleration.
Ultralights - in my experience of the Robin, yes, it's easy to buffet the roll off the top, however the problem is more likely to be one of reaching the top somewhere around, or even a bit below the level flight stall speed. Certainly you're unlikely to be capable of getting 4G. For a straight loop, that's less of a problem as you tend to float it over around 0G, but rolling off the top it's pretty easy to roll straight into a buffet / stall etc. Been a while since I aerobatted one, but I seem to recall adding 20kts to the entry for a roll-off or avalanche.
So as M gets bigger, the same force will produce a smaller A (or G loading) - the aircraft is somewhat less sensitive to gusts. Last time I checked, the POH for the oh-so-common Cessna 172 listed two Va values, one for MGW, and one for very light weight. I don't believe there is a specific turbulence penetration speed, Vno around 120something, Va 104(?), so Va is/was generally taken as a safe turbulence speed, at least as I was taught. (Caveat I've not flown a 172 for ages, hence being a bit vague)
Also of course as the a/c gets heavier, there's a practical limit to how much acceleration that the wing can produce without stalling - not that that's a particularly useful method of turbulence avoidance, and all of this is ignoring any secondary effects, other than immediate acceleration.
Ultralights - in my experience of the Robin, yes, it's easy to buffet the roll off the top, however the problem is more likely to be one of reaching the top somewhere around, or even a bit below the level flight stall speed. Certainly you're unlikely to be capable of getting 4G. For a straight loop, that's less of a problem as you tend to float it over around 0G, but rolling off the top it's pretty easy to roll straight into a buffet / stall etc. Been a while since I aerobatted one, but I seem to recall adding 20kts to the entry for a roll-off or avalanche.
