Steep Gliding Turn Principles

[sf340]

Hi there, I am shortly going to be doing my instructor rating. I am stuck on compiling a brief on the principles involved in a steep gliding turn.

Should I start off by explaining the forces in a level steep turn and then go onto the steep gliding turn? Obviously since the aircraft is descending lift must be less than weight, how would you draw these forces. And since the aircraft is descending do you still require an increase in lift? I think yes because to create the centripetal force you need to incline the increased lift vector, however since you are descending the vertical component of lift is less than weight?

I understand the steep turn and straight descent principles but I am finding it difficult combining the two. If you could possible give an explanation on how you would deliver the brief, explain the principles, or possibly give a link to a website that might explain it. All the briefs I have seen I don't believe are any good, and the explanations I have received I dont really understand.

Thanks in advance.

[BEagle]

"Obviously since the aircraft is descending lift must be less than weight..."

Back to your basic theory books, I think!

[QNH 1013]

If it is descending at a constant rate, then the vertical component of lift must equal the aircraft weight.
If the vertical component of lift is less than the aircraft weight, the rate of descent will be increasing.

[MadamBreakneck]

Oh dear chaps, are you really forgetting? In descending flight, part of the weight is counteracted by the vertical component of drag, innit?

MB

[flight259]

what?

not only during the descent, but even during the climb (at constant rate) the lift is less than weight, which is balanced not only by lift but by thrust as well.

[homeguard]

going down

The oldest and I think the simplest way to reflect the forces in a turn is to draw a parallelogram showing the the reduction in the vertical component of the lift force and an increase in total weight.
As bank is increased the load (centrifugal force) adds to weight (total weight) - the aircraft becomes heavier, while the lift (centripetal force) becomes increasingly a turning force with therefore a reducing vertical effect. Unless lift is increased and the vertical component (total lift) balances total weight the aircraft will descend. As bank is increased the aeroplane descends more steeply.
You should also include in your brief other factors such as; increase in the stalling speed ( the parallelogram will help explain) and the changes of attack of the inner and outer wings in the descent. This difference of wing incidence can be drawn but is more difficult and requires practice. I'm sure that you will find illustrations in most text books.

[QNH 1013]

I'm trying to keep it simple. In a flight with no vertical acceleration, i.e. level, or constant rate climb/descent, the vertical components of the forces must cancel out. Vertical components of thrust and drag are normally small in light aircraft compared to weight and vertical component of lift.

[jamestkirk]

lift

I cannot see what the relevance of lift is if you are descending.

[apollo85]

forces and application

ummmmm give this a shot: hopefully it should give you a basis, but im sure all the tools on this website will be quick to shoot down any single mistake i may make....... and give there 2 bobs worth without giving you an answer...as they seem to be!

forces:
only look at turning force >> concentrate on L and W.
L broken into its vectors has vertical lift (which balances the weight force) and horizontal lift vector (also know as centripetal force or turning force) which is what makes the ac turn.
application:
know in order to carry out any turn (level or steep) we are required to increase our lift in order to give us the required centripetal force to turn(even greater in a steep turn). now you get lift by increasing aoa >> but when you increase the aoa>> we create more drag >> and subsequently our airspeed decreases. !!!!!(butttttt in a glide it is realllly important you maintain your best glide speed. lets say it is 60kts.>> if your ias is decreasing due to drag, you must lower your nose to regain 60kts!)

therefore once you set up your glide at require airspeed, enter the turn with bank and balance (you may bring in underbanking here), and you will ahve to push forward on the stick to lower the nose to maintain glide speed. again the steeper the turn, the more hte drag the more you lower your nose!

is this ok??? hope it helps....ill try and post a turn diagram later

[jamestkirk]

apollo85

I WAS JOKING.

And hey, don't let them shot you down for being brave enough to give your opinion amoungst some of the ego kings on pprune.

the best one i heard was;

At the end of an ATPL course at oxford, one of the students asked the principles of flight tutor. " if lift is so important, why are we bothering to learn about drag". Priceless (obviously he/she was joking)

[bothok_teri]

Combining steep turn and descent,

I think its very simple guy
steep turn while descent makes the horisontal component of aerodynamic forces ( sin B x Lift ) increase your rate of turn and the vertical component ( cos B x lift ) become less so your rate of descent will increase...

thats all