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SR20 runway overruns OK-BOL at LKFR, and OK-AER at LZMA

Pilot_DAR wrote:

Is fiddling with flap settings during the takeoff roll, or greater than “takeoff” flap settings for takeoff described anywhere in the flight manual, or training material for the SR-20, or any other certified type?

Not in the SR20 Handbook. All takeoffs, irrespective of whether short field, soft field or normal, are performed with 50% flaps.

EDL*, Germany

Both of those will be back in the air after a good polishing.

I did takeoff & land with electric flaps U/S and stuck in 1/2 position and flew 800nm at slow speed buring load of fuel, just pragmatic flying TBH

Ibra wrote:

I find this attitude very worrisome. In Canada, the following regulation would have been violated by making that flight:

Aircraft Equipment Standards and Serviceability

605.06 No person shall conduct a take-off in an aircraft, or permit another person to conduct a take-off in an aircraft in their custody and control, unless the aircraft equipment required by these Regulations

(a) meets the applicable standards of airworthiness; and

(b) is serviceable and, where required by operational circumstances, functioning, except if otherwise provided in section 605.08, 605.09 or 605.10.

General aviation has very little room for pragmatism, everything is well described as to what may and may not be done. The list of may/maynot be dome is a result of a lot of unfortunate events, and lessons learned. If you need to fly with a defect, depending upon the defect, and urgency of the flight, you may apply for a flight permit, I’ve done it many times. The flight permit application process will assure dangers associated with the defect are mitigated as much as possible.

A flight conducted with defective flaps would have violated the terms of the insurance for the plane (“aircraft must be airworthy”). Thus any accident, particularly an accident involving degraded performance due to flaps being extended, would have not been covered by insurance. So I sure hope that you were flying a plane you owned, and not putting someone else’s asset at risk.

I find it worrisome that a pilot would “be pragmatic” in this regard, and worse, would post on the internet about it, such that impressionable pilots might think it’s okay to do that! Pragmatic thinking can result in accidents… How did this thread start? Pragmatic thinking about performance?

Last Edited by Pilot_DAR at 04 Jul 19:55
Home runway, in central Ontario, Canada, Canada

or any other certified type?

The Super Cub probably started the dynamic flap on take off technique so popular on YouTube. It is not in the normal procedures section but in the flight control description:

‘Half or full flap can be applied to reduce take off run, the more flap used the shorter the run. A minimum take off distance is obtained by beginning the take off with flaps up then applying full flaps when take off speed (30-35 mph) is achieved.’

It is a standard principle of flight and performance calculation axiom that TORR is reduced and TODR is increased when short take off flaps are applied. Reduced flap setting will increase TORR and reduce TODR. This is more pronounced in performance A turbine types, with the requirement to continue past V1 with an engine failure. OTOH This might not apply to MEP where there is acceleration to TOSS which is in effect above lift off speed (Vr being a swept wing jet concept). The Beech Baron in early POH famously would lift off 20 knots or so below Vmc with flaps 25, but modern AFM probably have dispensed with the STOL flaps 25 applied chart.

A typical example might be the 182 where the TORR is increased by 10% if take off is flaps 10 and not flaps 20 which minimises TORR.

Oxford (EGTK), United Kingdom

Airborne_Again wrote:

Certainly, but the Vr depends on flap setting.

I assume what he meant was the shortest ground roll to achieve, say, 60 kts, will be with flaps up. And then you can set, say, one stage of flaps. But, as he points out, it is not the safest of manoeuvres.

EGTR

Peter wrote:

On tarmac, shortest ground roll to reach a given Vr must always be with a clean aircraft.

Certainly, but the Vr depends on flap setting.

ESKC (Uppsala/Sundbro), Sweden

If you have to yes, why not? I did takeoff & land with electric flaps U/S and stuck in 1/2 position and flew 800nm at slow speed buring load of fuel, just pragmatic flying TBH

Paris/Essex, France/UK, United Kingdom

Ibra wrote:

you should stick to POH technique (except when flaps are U/S)

If the flaps are U/S, would you be taking off!?!

Really, really… just fly the plane the way the flight manual says!

Home runway, in central Ontario, Canada, Canada

Airborne_Again wrote:

I don’t agree about the flaps.

Neither do I.

Each certified type will specify the optimum flap setting for takeoff. In the case of one type I fly, flaps are either up, or down. They are to be selected down for all takeoffs and landings. On my taildragger amphibian, negative AoA certainly will not produce the shortest takeoff ground roll!

This is one of those situations where reading the flight manual, (thus following the approved manufacturer’s recommended technique), is far superior to taking seriously speculation and generalization posted by anonymous people on the internet.

Home runway, in central Ontario, Canada, Canada

Flaps & trim are as required by the pilot most of the time in gliders and un-certified types

For certified types, yes I agree one should stick to POH technique (except when his flaps are U/S) but as disclaimer the POH technique only guaranteed to work with published runway POH length requirement then plus blanket 40% safety factor, one will be dead stupid picking the former but not the latter, either pick all of it or none !

Last Edited by Ibra at 04 Jul 16:48
Paris/Essex, France/UK, United Kingdom
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