Recreational pilot's license flight test
Join Date: Nov 2000
Location: Melbourne,Vic,Australia
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Well, what is the stalling speed of a Tiger Moth at the top of a one G loop? isn't it same as straight and level (1 G environment)? The wing doesn't know it's upside down. Or, are we talking in terms of zero G at the top of the loop, in which case how can it ever stall?
At the top of a +1G(gauge) loop the wing will have an AoA of zero, which it will probably maintain* until it gets to the 270degree point (ie pointing vertically downwards).
PDR
* That's not necessarily guaranteed as there are lots of other factors that come into play in this, but at the top of a +1G(gauge) loop the aeroplane is in a zero-G state, and other factors notwithstanding the path from there to the 270degree point is ballistic rather than aerodynamic. The wing only needs to do work again for the recovery from the vertical dive to S&L flight.
PDR
* That's not necessarily guaranteed as there are lots of other factors that come into play in this, but at the top of a +1G(gauge) loop the aeroplane is in a zero-G state, and other factors notwithstanding the path from there to the 270degree point is ballistic rather than aerodynamic. The wing only needs to do work again for the recovery from the vertical dive to S&L flight.
Part 61 MOS for RPL knowledge required of Va would be the short definition of Va per the FAA in either of the two links that I previously provided. As someone pointed out, it is however good to give the answer considered correct by whoever is testing.
JT - yes, a very high pitch rate, I can provide numbers if you like. Were you going to mention hysteresis?
For more of a read of stuff related to Va, I like this: http://www.flightlab.net/Flightlab.n...aneuvering.pdf
PDR1 may like to look at the diagram of the loop on page 7 and reconsider the wing lift required to put +1 on the g meter at the top of a loop (perhaps a new thread on loops?).
JT - yes, a very high pitch rate, I can provide numbers if you like. Were you going to mention hysteresis?
For more of a read of stuff related to Va, I like this: http://www.flightlab.net/Flightlab.n...aneuvering.pdf
PDR1 may like to look at the diagram of the loop on page 7 and reconsider the wing lift required to put +1 on the g meter at the top of a loop (perhaps a new thread on loops?).
Last edited by djpil; 13th Jan 2017 at 19:15. Reason: Minor grammar again.
Around 1968 the RAAF had HS748's at the School of Air Navigation (SAN) based at RAAF Base East Sale and used for training navigators. At each graduation parade, a formation fly-past by HS 748's would take place. In those days it was common (but often unexplainable) for some RAAF aircraft to enter the circuit in formation at high speed on what was termed "the initial". Over the aerodrome, each aircraft in turn would then break left with a rapid 90 degree turn followed by a second rapid 90 degree turn on to the downwind leg. Aircraft would space themselves behind the aircraft in front to achieve separation on touch down.
Now all this was taught at RAAF Flying training schools as part of basic formation flying which would usually culminate into a "Buzz and break" manoeuvre as it was known. It was in turn (no pun intended) based upon WW2 fighter squadrons coming back from operational missions where there was no guarantee that enemy intruder aircraft were not waiting in the area to shoot down aircraft who were in the landing configuration with no speed to manoeuvre to avoid enemy fire.
Thus the idea was to keep landing aircraft at a high speed for as long as possible before configuring gear and flaps down. Rapid speed loss was attained by high G turns in the circuit. This was a fighter manoeuvre and never designed for heavier types which normally had a lower "G" limit than a fighter.
But because this "buzz and break"was taught to trainee pilots on Elementary and Basic Pilots Course, it led to pilots doing this when they flew other types and was considered good fun although quite unnecessary operationally. In my day we did buzz and breaks on four engine bombers as well as in DC3's if in formation. We did it on Tiger Moths and Wirraways, too. It was a good excuse for a bit of "hack - flick -zooming" and we probably all indulged in this aerial hooning at some time in our career from the lowest rank to Air Vice Marshal. Fine for fighter jocks but not really meant for other types.
Yet it goes on to this day with civilian pilots flying war birds like Harvards and even CT4's at air shows such as RAAF Point Cook, Victoria. To those of us long in the tooth, we see these fancy buzz and breaks at air shows as a bit of a wank by the pilots concerned pretending to be WW2 fighter pilots.
Thread drift finis. Back to the opening paragraph re the RAAF SAN HS 748 graduation fly pasts. Maybe they still do them on King Airs at East Sale?
Anyway, on one of the HS 748 formation fly pasts at RAAF East Sale, the formation leader (?) was going like the clappers on his initial run-in with other 748's trying to keep up. At the point where the first aircraft passed over the runway and made its 90 degree left (very) steep turn and using full control wheel deflection to get the turn going, the aircraft likely exceeded its Va and one aileron clean broke off. Fortunately the other aileron held and the 748 landed safely. One reason never to exceed Va..
Now all this was taught at RAAF Flying training schools as part of basic formation flying which would usually culminate into a "Buzz and break" manoeuvre as it was known. It was in turn (no pun intended) based upon WW2 fighter squadrons coming back from operational missions where there was no guarantee that enemy intruder aircraft were not waiting in the area to shoot down aircraft who were in the landing configuration with no speed to manoeuvre to avoid enemy fire.
Thus the idea was to keep landing aircraft at a high speed for as long as possible before configuring gear and flaps down. Rapid speed loss was attained by high G turns in the circuit. This was a fighter manoeuvre and never designed for heavier types which normally had a lower "G" limit than a fighter.
But because this "buzz and break"was taught to trainee pilots on Elementary and Basic Pilots Course, it led to pilots doing this when they flew other types and was considered good fun although quite unnecessary operationally. In my day we did buzz and breaks on four engine bombers as well as in DC3's if in formation. We did it on Tiger Moths and Wirraways, too. It was a good excuse for a bit of "hack - flick -zooming" and we probably all indulged in this aerial hooning at some time in our career from the lowest rank to Air Vice Marshal. Fine for fighter jocks but not really meant for other types.
Yet it goes on to this day with civilian pilots flying war birds like Harvards and even CT4's at air shows such as RAAF Point Cook, Victoria. To those of us long in the tooth, we see these fancy buzz and breaks at air shows as a bit of a wank by the pilots concerned pretending to be WW2 fighter pilots.
Thread drift finis. Back to the opening paragraph re the RAAF SAN HS 748 graduation fly pasts. Maybe they still do them on King Airs at East Sale?
Anyway, on one of the HS 748 formation fly pasts at RAAF East Sale, the formation leader (?) was going like the clappers on his initial run-in with other 748's trying to keep up. At the point where the first aircraft passed over the runway and made its 90 degree left (very) steep turn and using full control wheel deflection to get the turn going, the aircraft likely exceeded its Va and one aileron clean broke off. Fortunately the other aileron held and the 748 landed safely. One reason never to exceed Va..
Last edited by Centaurus; 14th Jan 2017 at 10:29.
we see these fancy buzz and breaks at air shows as a bit of a wank by the pilots concerned pretending to be WW2 fighter pilots.
Also a good efficient way to split up a formation and get suitable downwind spacing depending on the timing between aircraft pitching out.
Moderator
yes, a very high pitch rate, I can provide numbers if you like. Were you going to mention hysteresis?
Pitch rate would be useful to know. Not hysteresis as a consideration.
The flightlab link she's a not work too well .. perhaps you can check ?
Pitch rate would be useful to know. Not hysteresis as a consideration.
The flightlab link she's a not work too well .. perhaps you can check ?
"Pitch rate would be useful to know." JT, I have emailed you a couple of references: SAE Paper 700222 Loading Conditions Measured During Aerobatics and an IAC Technical Safety Report from 1987 on the effect of abrupt elevator deflection. Both available online but not easy to find nor free.
"The flightlab link she's a not work too well .. perhaps you can check ?" Works fine for me - goes to a direct download of the pdf but try this link http://www.flightlab.net/Flightlab.n...rse_Notes.html and its #8 on the list of documents.
"The flightlab link she's a not work too well .. perhaps you can check ?" Works fine for me - goes to a direct download of the pdf but try this link http://www.flightlab.net/Flightlab.n...rse_Notes.html and its #8 on the list of documents.
