Menu Sign In Contact FAQ
Banner
Welcome to our forums

Flaps for take-off, why?

A POH can not cover all eventualities unless testing goes on forever and the POH is the size of a house. It is the reason why it says max “demonstrated” crosswind.
The POH says use 1 notch of flap for a short field take off. It’s a gravel runway. There’s no mention of runway conditions in the POH. Do you use flap or not?
This was one of the multi choice questions in the PPL theory exam back in the early 1990’s.

France

The POH says use 1 notch of flap for a short field take off. It’s a gravel runway. There’s no mention of runway conditions in the POH. Do you use flap or not?

High wing or low wing and who pays for the paint?

You have to opt for soft takeoff technique with partial flaps (even go full flaps if you wish if runway is unlimited and you have some power), full back pressure and apply smooth gradual power to protect the prop

Last Edited by Ibra at 08 Mar 08:26
Paris/Essex, France/UK, United Kingdom

I don’t recall whether or not the question mentioned high or low wing. But I suppose it was accepted as low wing as most French trainers with flaps at the time were Robins or Rallyes.🙂
The answer to the multi choice question (although the French multi choice was a “cailloux” surface which I think translates more as pebbly than gravelly)
was no flaps for fear of damaging the flaps.
I will never forget the question as it was one I got wrong during my PPL theory exam.
But, I suppose getting it wrong has taught me to analyse things more than just read the POH or listen to an instructor.

France

RobertL18C wrote:

While most MEPs use flaps for a short field technique, it can either lead to wheelbarrowing or lift off before safety speed. Hence the majority of light twins the normal take off is flapless.

As a very wise high time King Air pilot once said to me, why take off with flaps you don’t need? If an engine fails on a multi engine propeller aircraft you will have enough work to do getting the thing to climb, and flaps are just one more item to deal with.

On most jets flaps are needed to ensure you are well away from tyre limitations, and to keep accelerate stop distance within the available runway length. In certain circumstances it is permitted to use flaps zero with a long enough runway, but the decision is complicated. It is sometimes better to use flap zero when you start to consider OEI climb gradient performance when obstacle clearance is tricky

Darley Moor, Gamston (UK)

Neil wrote:

It is sometimes better to use flap zero when you start to consider OEI climb gradient performance when obstacle clearance is tricky

Are there any twins where the OEI climb gradient at Vxse is better with flaps than without?
Unicorn twin

Paris/Essex, France/UK, United Kingdom

Ibra wrote:

Are there any twins where the OEI climb gradient at Vxse is better with flaps than without?

I don’t know about all twins, but for the ones I fly there’s a desire to use flaps 15 for takeoff to give more Accelerate/Stop distance, but the OEI Second Segment Net Climb Gradient is improved with flaps 0

Darley Moor, Gamston (UK)

Airborne_Again wrote:

In situations where the PA28 POH does suggest the use of flaps for take-off it says 25°.

Just out of curiosity. What is 10 degree used for?

The elephant is the circulation
ENVA ENOP ENMO, Norway

@LeSving the only use for flaps 10o on a PA28 is on an instrument approach. Typically at 90KIAS, flaps 10o gives you a slightly nose down attitude so easier to transition to visual, and helps with speed control.

Some aircraft types use flaps 10o with a higher Vfe than Vle helping slow before gear extension. For those who worry about retractable gear being extended there is (I believe an old PanAm SOP) the philosophy to always deploy landing gear, confirm three green, before deploying flaps, and always extending landing gear at the same point in the relevant phase of flight. Possibly a subject for a different thread.

Edit: also to retract in stages, which when I think about it is probably the root reason for one notch flaps. Dumping (ie retracting at once ) flaps 25 on a low go around might be exciting on a warm day in close to gross in a Cherokee.

Last Edited by RobertL18C at 09 Mar 06:03
Oxford (EGTK), United Kingdom

LeSving wrote:

Just out of curiosity. What is 10 degree used for?

To reduce the possibility of a pilot being shocked by the sudden handling change of instantly being at 25 degrees?

Many decades ago I was right seat passenger to my boss. He’d p$$ed me off that day, and I was silently enduring a night flight home in the old 182 with him. He knew I was p$$ed, so he too said nothing. It was a dark night, two hour flight, I just sat….. I had noticed that he had failed to retract the ten degrees of flap after takeoff, and he’d been flying the better part of an hour with the flaps a little extended. Being a 182A, the flaps were manual, like a 180/185. I had initially ignored this, but now saw an opportunity. I slid my hand down unseen, pulled on half a degree, pushed the button, slowly released one degree, just past the lock of the ten notch…. and just dropped the flap lever. Okay, the plane probably dropped only two feet, but it was sudden, accompanied with the bang of the flaps retracting to zero. He was totally startled, looking around to see what had happened… I calmly said, that I’d noticed he’d forgotten to retract the flaps, and I just thought I’d take care of it for him. The mood lightened, and we’re still friends….

Home runway, in central Ontario, Canada, Canada

RobertL18C wrote:

For those who worry about retractable gear being extended there is (I believe an old PanAm SOP) the philosophy to always deploy landing gear, confirm three green, before deploying flaps, and always extending landing gear at the same point in the relevant phase of flight

Some airplanes are difficult to slow down before the gear is down. The Mooney has this procedure as well. Gear first, then first stage of flaps.

LSZH(work) LSZF (GA base), Switzerland
80 Posts
Sign in to add your message

Back to Top