MAx Rate Turns

[jamup]

Can somebody please tell me how to do this Max rate turn right . I am getting this wrong again and again .....Please

[Tinstaafl]

What is it you're getting wrong? Or, if you're not sure what's wrong, what is it that's happening when you try to do them?

[High Wing Drifter]

First a balanced turn of 30deg of bank and then full power and increase to 60deg of bank. Balance with the rudder and impart a considerable amount of back pressure to stop the aircraft entering a steep descending turn.

If you start to descend increase back pressure and/or reduce the bank slightly.

If you start to climb, reduce back pressure and/or increase the bank slightly

DO NOT EXCEED 60deg of bank.

Do all these things properly and you will feel a bump as you travel through your own wake :D

Start to level off 25-30deg before you're desired heading.

[IO540-C4D5D]

What is a "max rate turn" - is it 60 degrees? I don't recall ever hearing this expression in the PPL.

[Another St Ivian]

I always thought that a Max Rate turn was just that, a turn of maximum performance, i.e. flying on the light buffet. The way I have done them in short is full throttle, roll the aircraft over to about 60 degrees then pull until I feel the light buffet and use the angle of bank to control RoC/RoD.

A.S.I

[Evo]

A max-rate turn as I understand it is >60degrees (I think about 75 degrees in the Robin I fly) - full power, and turning on the edge of the accelerated stall. It's "max rate" because there's no power to turn harder. Get it right and you can do a 360 while feeling the stall buffet and then bump through your wake. Good fun :ok:

(edit: looks like ASI just beat me to it :) and for spelling :O )

[BEagle]

Enter a normal 45 deg AoB steep turn.

Increase angle of bank to 60 deg, increase power to full throttle and then increase bank and back pressure further until the aircraft is turning on the buffet nibble in level flight. Use sufficient rudder to keep the ball centered; if the ac starts to descend then reduce bank slightly whilst maintaining the buffet nibble.

For a max rate possible turn, once the max level turn has been achieved, increase the bank yet further until a descent has started. Then keep increasing bank and back pressure until you're turning with full power, on the buffet nibble and at the maximum permitted 'g' for your aeroplane. Not easy - but it'll turn like crazy!


Do NOT do any of the above without first having first been taught how to do so safely. It is very demanding and most civilian GA pilots will not have been trained to fly their ac at the limits of its performance. When we students used to do this in the Folland Gnat, we had to trim to +5g and then squeeze to +6g on the buffet nibble whilst looking backwards over our shoulders to see how many fingers the QFI was holding up!

[bluskis]

Beagle

I notice that unlike many posters you advocate rolling into the bank then applying full power. Before your post I thought I was missing something.

A max rate turn would be the shortest time to execute 360, or what ever change of heading you chose. I think I like your idea of allowing a descent during the turn to achieve this.

Does a canyon turn count as a max rate turn?

Question? Does a max rate turn correspond to a minimum radius turn?

[Shaggy Sheep Driver]

It's important to remember that if a descent starts, rol off some bank. Just pulling back will simply steepen the turn and the rate of descent.

I must try BEagles idea of allowing descent to get a max turn rate, but I suspect the Chippy would get near VNE pretty quickly in such a manouvre, long befor it reches max 'G'.

(if this looks like happening, or anything else untoward, roll wings-level while whacking off the power, and pull out of the dive not exceeding max allowable 'G')

I'll try it and see (carefully!)

SSD

[BEagle]

The point is that very few ac have sufficient thrust to be able to maintain the bufet nibble in level flight at their max permitted g. The only thing I've flown which would was the Hunter GT6 - full power, buffet nibble and +6 g at low level and it would actually climb....

So in a light puddlejumper, if you can maintain the buffet nibble at 70 deg AoB and full power you'll be doing +3.9 g. To get any further increase in rate of turn, allow a slight descent to start and then increase AOB and back pressure until you're at the limiting g value on the buffet nibble with full power. Do NOT try this without a g meter AND dual instruction!



...NEVER 'whack off the power'! Throttle back gently instead.

[DB6]

If you think about it, you need two things for a turn at max. rate:1) max. lift and 2) max. AoB to put that lift to use in the direction you want. Now lift=1/2 rho Vsquared S (stop that cold sweating at the back!); S is fixed unless you have fancy gadgets on your wings, rho decreases with height so you will get faster turn rates lower down, and v depends on your power - use full power. The technique for flying an MRT is as BEagle describes but it is important to note the subtle difference in control technique; you are using elevators to control the angle of attack - to stay on the buffet (NB not just the stall warner) so you cannot use them to control attitude. That is done using the ailerons to control AoB to raise or lower the nose. Note now that as the nose rises speed will decrease so less back pressure is required to maintain the buffet, conversely in the descent. You should still be using a Lookout-Attitude-Instrument scan but the only instruments that are of use are the altimeter/vsi and balance ball and the lookout will be directed through the top of the canopy (Cessna drivers stretch your necks). Also note that when you roll out your initial level flight attitude will be that for the speed at which the turn has stablised, not necessarily the same speed as at entry.
Any questions? :E :ok: :E :ok: :E :cool: :D

[Stan Evil]

Shaggy Sheep Driver. In a max rate possible turn you are on the buffet at max allowable g but that won't be very fast. You can work out the speed by taking the square root of your max load factor and multiplying it by the basic stall speed. This is actially the manoeuvre speed for an aircraft - the speed at which you can pull to the buffet without overstressing the aircraft.

However, if you have not received any instruction in this technique DO NOT TRY IT for the following reasons: it will generate a horrendous rate of descent; a moment's inattention and you will come off the buffet, and the speed WILL race towards VNE as well as busting max engine rpm if you don't have a VP prop; finally, and most importantly, if you're not used to a sustained high 'g' you'll probably black out and may or may not come round before hitting the ground - I blacked myself out in a Jet Provost when solo a long time ago and do not recommend it.

[BEagle]

Stan Evil is quite right. In a Bulldog, the max possible turn requires 4.75 g at 109 KIAS. That would mean a level turn with 78 deg AoB if you had sufficient thrust available - the drag incurred being something like 2.1 times the drag in the stabilised max rate level turn limited by available engine power (about 2.4 g, 75KIAS and 65 deg AoB), so a controlled spiral descent on the buffet with full power is needed. This was not a manouevre which we taught in the Bulldog, although it was possible - and very difficult.

DO NOT TRY THIS without a very experienced instructor and an awareness of your own g tolerance, physical and medical condition. Descending in a controlled high g turn on the buffet is a very, very demanding and disorientating manouevre which can be highly dangerous.

[Nozzles]

Gentlemen,

To clear up some definitions for those who asked:

An aeroplane's Best Instantaneous Rate of Turn occurs at the minimum speed that will generate airframe-limiting g. Because it is the minimum speed at which this occurs, you will be in the light buffet. In fighter parlance this speed is known as Corner Velocity, and gives you your highest rate of turn in terms of degrees per second. It does not give you the aircraft's minimum turn radius. Most aeroplanes do not have the power-to-weight ratio to maintain this in a level turn, and so, as has been previously discussed, the Instantaneous turn tends to be a spiral-hence its name-you can't keep it up for ever.

The Best Sustained Rate of Turn is the maximum turn rate that can be achieved whilst maintaining level flight. This occurs at a slower speed than Corner Velocity, and is known as a 'Power (or Thrust) Limited Turn'. This is because the amount of back-pressure you apply creates just enough drag to match your thrust, and thus the aeroplane can maintain both the airspeed and the turn rate. It is short of the light buffet, and the turn rate can be temporarily improved by pulling to the light buffet (the top of the CL curve). However, for most aeroplanes, this will result in a bleeding of speed and an eventual reduction in turn rate.

A Minimum Radius turn occurs at an even slower speed than either of the above. As an aeroplane slows down for a given g loading, its turn radius will decrease. There is a point on the graph at which, if you slow down further, the reduction in radius the slower speed should give you is offset by the reduced turning capability provided by the dwindling g. This point is Min Radius Speed. It usually occurs in full flap configurations as this configuration gives the highest lift harvest for the lowest speed input.

I would like to echo the previous recommendations that such stuntery is NOT attempted without proper training.

[High Wing Drifter]

I kind of assumed Jamup was a PPL student not doing a Tornado GR4 conversion course!

All interesting stuff though :)

[bluskis]

Nozzles

Thanks for the summary, and thanks to all for the health warnings.

[Shaggy Sheep Driver]

BEagle and Stan - point taken about solo experimenting with max rate turns. Perhaps one to save for the bi-annual, with my fave aeros instructor.

SSD

[mad_jock]

On my FIC the instructor demo'd what happens if you over cook it in the turn then use roll.

The world starts doing some very strange things. After it settles down you are in a full developed spin going the oppersite direction you were turning.

I put it into the sod that for a game of solders demo's. Never been brave enough to try it in a tomahawk.

MJ