Re: Base to Final Turn
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Re: Base to Final Turn
Can someone explain why the civvy circuit pattern is square, with 2 tightish 90* turns close to the ground on finals and relatively slow?
After looking at recent accidents I thought about the way I learned in Motorgliders in the RAF VGS. This was a constant turn from downwind abeam the numbers until short finals, at about 15-20* AOB. The approach speed was selected before making the turn and maintained until touchdown - 65-75kts depending upon wind.
I found it quite hard to adjust to the PPL way because a constant easy turn seems easier than 2 tight turns. It may be down to Gliders having smaller turn radii (radiuss? not to good with spelling).
This is more out of interest and is not meant to be derogatory.
Thanks Shaft
After looking at recent accidents I thought about the way I learned in Motorgliders in the RAF VGS. This was a constant turn from downwind abeam the numbers until short finals, at about 15-20* AOB. The approach speed was selected before making the turn and maintained until touchdown - 65-75kts depending upon wind.
I found it quite hard to adjust to the PPL way because a constant easy turn seems easier than 2 tight turns. It may be down to Gliders having smaller turn radii (radiuss? not to good with spelling).
This is more out of interest and is not meant to be derogatory.
Thanks Shaft
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Shaft109, what you were taught is the standard military circuit. I can see many advantages to it but not that many disadvantages, myself, though perhaps others will come up with ideas. Principal benefits:
a. it keeps the circuits small and within the ATZ;
b. as a result most of the circuit is within gliding range of the runway or at least the airfield if it all goes quiet;
c. more circuits per hour = cheaper training.
OTOH there are fewer 'slots' in the circuit at once, but then that hardly matters if you can do one every 4 minutes (my average at home base).
Tim
a. it keeps the circuits small and within the ATZ;
b. as a result most of the circuit is within gliding range of the runway or at least the airfield if it all goes quiet;
c. more circuits per hour = cheaper training.
OTOH there are fewer 'slots' in the circuit at once, but then that hardly matters if you can do one every 4 minutes (my average at home base).
Tim
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I have no Knowledge of military circuits but I can see a lot of benefits to what you suggest.
Sometimes I think that much of what we practise in GA is so steeped in tradition and 'the way it should be done' that we complacently blunder on doing the same old stuff.
Overhead re-joins are a perfect example of 'tradition' which was based on the poor climb performance of much older aircraft. I believe that the crossing of the numbers to downwind is now an accident waiting to happen with the much higher climb performance of modern kit and microlight type aircraft.
Sometimes I think that much of what we practise in GA is so steeped in tradition and 'the way it should be done' that we complacently blunder on doing the same old stuff.
Overhead re-joins are a perfect example of 'tradition' which was based on the poor climb performance of much older aircraft. I believe that the crossing of the numbers to downwind is now an accident waiting to happen with the much higher climb performance of modern kit and microlight type aircraft.
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Big fan of military oval circuits.
Nominal angle of bank used in the climbing upwind turn varies from 20-60deg, depending on the performance of the aircraft, to achieve a standard downwind spacing that enables a landing on the airfield should the donk fail. Finals turn uses 15-45deg AoB, again dependant on aircraft performance, to achieve the required turn radius.
Angle of bank varied for crosswind - more bank when turning "with" the wind, eg upwind turn with a slackening wind, and less bank when turning into it.
Anyone actually got any good reasons for doing square circuits, generally out of gliding range of the airfield and outside even the ATZ?
Nominal angle of bank used in the climbing upwind turn varies from 20-60deg, depending on the performance of the aircraft, to achieve a standard downwind spacing that enables a landing on the airfield should the donk fail. Finals turn uses 15-45deg AoB, again dependant on aircraft performance, to achieve the required turn radius.
Angle of bank varied for crosswind - more bank when turning "with" the wind, eg upwind turn with a slackening wind, and less bank when turning into it.
Anyone actually got any good reasons for doing square circuits, generally out of gliding range of the airfield and outside even the ATZ?
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Anyone actually got any good reasons for doing square circuits, generally out of gliding range of the airfield and outside even the ATZ?
In a militiary circuit, is the downwind equilivant still straight? ie. curve on take off until downwind....straight downwind, and then curve to touch down? Or is is just one big curve?
How does one join a militiary circuit?
dp
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Originally Posted by dublinpilot
How does one join a militiary circuit?
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Mil Cct Joins:
Standard Join:
Join via 'Initials' - on extended centreline of active runway, about 3nm back from threshold. Run in deadside (ie keeping clear of any cct traffic liveside) at cct height, adjusting position where you turn downwind to fit in with traffic in the cct.
Run and Break:
Much like the standard join, but running in lower and faster than standard join, then using the break up (often to cct height) to help bleed the speed off. Break position again adjusted to fit in with existing traffic.
Of course, one can also position at hi-key for the active runway for a PFL or join downwind. Downwind leg is indeed parallel to the runway.
Join via 'Initials' - on extended centreline of active runway, about 3nm back from threshold. Run in deadside (ie keeping clear of any cct traffic liveside) at cct height, adjusting position where you turn downwind to fit in with traffic in the cct.
Run and Break:
Much like the standard join, but running in lower and faster than standard join, then using the break up (often to cct height) to help bleed the speed off. Break position again adjusted to fit in with existing traffic.
Of course, one can also position at hi-key for the active runway for a PFL or join downwind. Downwind leg is indeed parallel to the runway.
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The constant-turn descent is the way I fly all my circuits in the Pitts and Taylorcraft. Works a treat. It's especially common in taildraggers because keeping the runway off the nose allows you to actually see it during the descent - a straight in final approach masks the runway under the nose and you end up coming in blind. I hate straight in approaches with a taildragger. Doing it this way also encourages coming in with some slip in as well, increasing the visibility past the nose and giving you extremely good control of positioning and airspeed.
Pitts2112
Pitts2112
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Pitts:
Not for one moment disagreeing with you, for your type of aircraft I'm sure that type of approach is ideal.
However, lest anyone gets confused, the oval circuit I described features a straight final approach after a descending 180 degree finals turn.
Not for one moment disagreeing with you, for your type of aircraft I'm sure that type of approach is ideal.
However, lest anyone gets confused, the oval circuit I described features a straight final approach after a descending 180 degree finals turn.
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Originally Posted by Fournicator
Pitts:
Not for one moment disagreeing with you, for your type of aircraft I'm sure that type of approach is ideal.
However, lest anyone gets confused, the oval circuit I described features a straight final approach after a descending 180 degree finals turn.
Not for one moment disagreeing with you, for your type of aircraft I'm sure that type of approach is ideal.
However, lest anyone gets confused, the oval circuit I described features a straight final approach after a descending 180 degree finals turn.
Yep but still essentially the same thing, unless you're talking about an extended straight final. In the case above as with most high performance taildraggers (hence the technique often being called a Spitfire Curved Approach), you'll find the curve finishes more or less around the numbers or a bit short of them with the exact details a matter of specific conditions and pilot preference. I prefer to hold the slip in until almost touchdown but will straighten out the curve further back away from the numbers depending on how short I want to land and how short a landing roll I want to have.
In both cases, you're still only talking about a straight bit of less than a couple hundred meters. Is that what you mean or are you talking something else?
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Sorry Fournicator
Please accept my apology it's what my rubbish instructor taught me he quoted page 223 exercise 13a of book 1 flight training by Capt Peter Goodwin I didn't mention airspeed because that was not what I was leading to, I kind of thought that was commonly understood, once again please accept my apology. Should I write to Capt Goodwin
Please accept my apology it's what my rubbish instructor taught me he quoted page 223 exercise 13a of book 1 flight training by Capt Peter Goodwin I didn't mention airspeed because that was not what I was leading to, I kind of thought that was commonly understood, once again please accept my apology. Should I write to Capt Goodwin
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Having had a few occasions on a straight in approach where not just the runway disappears, but sometimes the whole airfield did, I am addicted to the curving approach. Besides which, it feels so good!
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Pitts:
A mil cct commonly has a final approach of just under a mile, probably a bit longer than you had in mind! Not that I'm not a fan of the appraoches you describe, especially for the aircraft we're talking about, but just to make clear the ccts I was originally describing.
A mil cct commonly has a final approach of just under a mile, probably a bit longer than you had in mind! Not that I'm not a fan of the appraoches you describe, especially for the aircraft we're talking about, but just to make clear the ccts I was originally describing.
Thread Starter
A bit more info
The A/C in question is a Grob 109, it's a taildragger so a curved approach is appropriate really thinking about it.
www.military-airshows.co.uk/ abingdon2005/1750.jpg
To clarify what I learned i'll go through a basic circuit as is remember it, from 1998 ish as it might have changed, and my point is how it is simpler than a PPL style circuit.
All heights in QFE, and ignore the fact you actually "glide".
Take off and climb at 60kts straight out to 800ft (ROC 400fpm) "Pause" I was told a few times!
Level at 800ft, 60kts. Turn at about 15-20*AOB until downwind (also a constant turn). Maintain 60kts, 800ft until mid point downwind. Now A.P.T. reduce power to idle and maintain 60 kts in the glide, still on downwind.
As the piano keys meet the leading edge increase to approach speed 65-70kts in the glide, usually at 700' by this stage. Still on downwind.
As piano keys come out under trailing edge start turn at about 15-20* AOB.
Halfway round you should be at about 500' (Still air).
Roll out on finals at about 300' still having maintained approach speed. Land.
Joining was either 45* into downwind at cct height, or 90* to the upwind piano keys if you were engine off. (although at 900')
Basically the point I am trying to make is you are climbing, turning then descending steadily but not all at the same time. You have broken it down into little bits.
I can't help but think that the young lad down south in the Cessna 150 who died last week could have been trying to do more than one thing at once, forgot about airspeed then it got away from him. Maybe tightening the turn to stay square. Incidentally I was also 16 and had about 10 hours on my subsequent solos, which is what got me thinking about base final turns.
As for EFATO's well turn back from 300', or fly a mini cct at 500'. (As you can tell i loved that plane
.
www.military-airshows.co.uk/ abingdon2005/1750.jpg
To clarify what I learned i'll go through a basic circuit as is remember it, from 1998 ish as it might have changed, and my point is how it is simpler than a PPL style circuit.
All heights in QFE, and ignore the fact you actually "glide".
Take off and climb at 60kts straight out to 800ft (ROC 400fpm) "Pause" I was told a few times!
Level at 800ft, 60kts. Turn at about 15-20*AOB until downwind (also a constant turn). Maintain 60kts, 800ft until mid point downwind. Now A.P.T. reduce power to idle and maintain 60 kts in the glide, still on downwind.
As the piano keys meet the leading edge increase to approach speed 65-70kts in the glide, usually at 700' by this stage. Still on downwind.
As piano keys come out under trailing edge start turn at about 15-20* AOB.
Halfway round you should be at about 500' (Still air).
Roll out on finals at about 300' still having maintained approach speed. Land.
Joining was either 45* into downwind at cct height, or 90* to the upwind piano keys if you were engine off. (although at 900')
Basically the point I am trying to make is you are climbing, turning then descending steadily but not all at the same time. You have broken it down into little bits.
I can't help but think that the young lad down south in the Cessna 150 who died last week could have been trying to do more than one thing at once, forgot about airspeed then it got away from him. Maybe tightening the turn to stay square. Incidentally I was also 16 and had about 10 hours on my subsequent solos, which is what got me thinking about base final turns.
As for EFATO's well turn back from 300', or fly a mini cct at 500'. (As you can tell i loved that plane
.
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Constant aspect
I use constant aspect on my turns for PFLs I find this straight forward and very precise and above took least time to master (well sort of). Thats how circuits could be flown.
Nobby
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Ah, right. Sure. Since the military no longer fly taildraggers, there's no reason to carry a slip or curve as deep into final approach.
In the curved approach, I find it much easier to estimate, right from the beginning of the descent, how the whole thing is going to go and what slight variations I'm going to need to make to hit my mark. I find that harder to do in an approach with two vectors 90*s appart. Maybe that's why the military do it that way? Also, one curve which is constantly updated is actually easier to fly and is less disruptive/discontinuous than two legs 90*s apart.
Would love to get an hour in an F-15E to see for myself!
Pitts2112
In the curved approach, I find it much easier to estimate, right from the beginning of the descent, how the whole thing is going to go and what slight variations I'm going to need to make to hit my mark. I find that harder to do in an approach with two vectors 90*s appart. Maybe that's why the military do it that way? Also, one curve which is constantly updated is actually easier to fly and is less disruptive/discontinuous than two legs 90*s apart.
Would love to get an hour in an F-15E to see for myself!
Pitts2112
Thread Starter
Re: Tonyhalsall
You made a good point about that old schoolmaster style "this is how it should be done!". It might look neat but is it the safest and most appropriate way now?
I have been boll**ed before by a civvy FI when I took off on the right parallel runway and turned 5* to the right to give a little bit more separation (at maybe 100') from the left runway. It was a very gentle bank BTW less than 5*.
"no turn below 500'!" I was told. Why? Apart from the fact I am used to doing full turnbacks from 300' I specifically did this because there was a fatal collision from just this sort of departure where the left guy drifted to the right, and the right guy drifted to the left. And seeing the attempts some students make........, that bit to the right might save your bacon.
I was just being a bit proactive and roasted for not following proceedure to the letter. This kind of attitude just doesn't make sense to me.
I have been boll**ed before by a civvy FI when I took off on the right parallel runway and turned 5* to the right to give a little bit more separation (at maybe 100') from the left runway. It was a very gentle bank BTW less than 5*.
"no turn below 500'!" I was told. Why? Apart from the fact I am used to doing full turnbacks from 300' I specifically did this because there was a fatal collision from just this sort of departure where the left guy drifted to the right, and the right guy drifted to the left. And seeing the attempts some students make........, that bit to the right might save your bacon.
I was just being a bit proactive and roasted for not following proceedure to the letter. This kind of attitude just doesn't make sense to me.
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Am I correct in thinking that the Militiary circuit is more like image no 1 then, and less like image no 2?
Do I understand F correctly, in that the standard join in a militiary circuit is per the red line in image no 3?
dp
Do I understand F correctly, in that the standard join in a militiary circuit is per the red line in image no 3?
dp