Cherokee take off flaps 10.

[Dude~]

Can anyone explain why Piper do not provide performance figures for take off in Warriors, Archers and Arrows with 10 degrees of flaps?

Does anyone use it and if so why? I have done so - it seems sensible when you want the extra lift but not the reduced climb rate associated with 25 degrees. However, why does the manufacturer not mention it. Is there an important reason for this.

Interested to hear any comments.
-------
Having read some reports on the AAIB site, I have come across this report which answers my own question. Doh!

The Pilot’s Operating Handbook (POH) provides unfactored performance figures based on flight test data using a new aircraft and engine. Take-off data assumes that full throttle is applied before brake release and that the runway is a dry, paved, level surface. The POH makes no mention of flap 10° as a recommended take-off flap setting and no performance data for flap 10° is provided; however, flap 0° and flap 25° data is given. The recommended flap setting for a short field take off is flap 25°. The remainder of this performance analysis provides figures for both flap 0° and flap 25° on the assumption that flap 10° performance lies somewhere between the two.

[This message has been edited by Dude~ (edited 07 June 2001).]

[Chilli Monster]

Taking it one stage further - I don't think I've ever felt the need to use 10 degrees in a warrior. Half decent length Tarmac - none, Short Grass strips 25 as the book says. I honestly think that you might be asking for trouble using 10 in the latter circumstances, but then I've never tried it (and DON'T intend to).

CM

[This message has been edited by Chilli Monster (edited 08 June 2001).]

[Yogi-Bear]

Read the accident report on the Seneca that went in at Newmarket and you might draw some conclusions.

[Bouncy Landing]

Ive always understood that 10* on a Warrior gives no benefit in takeoff. If you NEED flaps for takeoff you need 25*.

[Cough]

I have done several F10 departures in PA28 type aircraft and prefer it to a standard take off. The visibility it offers is much better, and the aircraft lifts off as opposed to crawls off. Its a personal thing. As CM says, if its short then you NEED F25. No question.

The Newmarket accident has little relevance to this debate as we are talking single vs. twin. Engine failure in a single is a simple decision. Down!

CCCC....ough

[Cough]

To cover yourself though, do the performance for F0 and F25, then the F10 departure performance should follow.

Cccccccc....ough

[Office Update]

Dude~ I'll save you the embarrasement of a court appearance.

(1) Use the factory recommended technique at all times.
(2) Don't listen to bar room and aero club 'rules of thumb' the manufacturer employs the best people in the world to make their product perform safely.

[Dude~]

Bouncy - surely flaps 10 must give some benefit.

Yogi - what conclusions do you draw from the twin accident? That flaps 10 leads to wheelbarrowing?! If you expect a flatter attitude then you can prepare for it - no excuse for prop strikes.

I agree with Cough, that if a field is semi- marginal, then use the data for 0 flaps but take off with 10, and expect slightly shorter take off run. This IS in compliance with the POH although it is of course up to the pilot to make a sensible extrapolation of data.

In the same way, one could use flaps 5 on a C152.

[Final 3 Greens]

Dude

To answer your question, Piper provide data for the settings that they wish you to use for the aircraft. They have tested the aircraft with these settings.

It is therefore reasonable to conclude that they do not intend you to operate the aircraft using other settings.

As others have said on the thread, it is best to use the manufacturers settings, unless you consider yourself to be a test pilot!

[juswonnafly]

More flap = more drag = reduced rate of climb

The important point here is 'what is required of the take off'

Short field....obstacles.....25 flap

It also of course depends on the runway surface. At the end of the day, do what it suggests in the POH, the manufacturers do know best (but DO 'factor' everything!)

JWF

[This message has been edited by juswonnafly (edited 09 June 2001).]

[Bouncy Landing]

I've always understood that on a Warrior 10* flaps gives drag but no appreciable lift - fine for approach, but not a great asset on takeoff.

[Cough]

Now not many people use F10 on the approach due to the fact it does not give much useful drag (needed on approach). Hence at most of the schools I have been to, you go straight from F0 at the end of the downwind to F25 on base. Works well.

I am not claiming that F10 will markedly reduce your take off distance. Nope. I am also not claiming that it should be used on short soft fields. F25 will do that one!

All I said is I prefer it on take off as the aircraft, due mostly to the increase in effective angle of incidence of the wing, gives a lower deck angle on climb out. The visibility is better, and the aircraft lifts off as opposed to being dragged off the ground.

My preference thats all.

Ccccccc....ough

[Grandad Flyer]

Dude, I hope you have good insurance! Might be a bit tricky explaining to the CAA why you were operating outside the manufacturer's recommended operation and outside of the operating handbook.
If I was you I would be scanning my insurance very thoroughly as there is usually a clause in there about operations outside of the norm.
If you want to find out more why not get in touch with either Piper or their UK agent and ask them about it? If you could get something in writing from them saying its OK then at least you'd be covering your ar*.
By the way, I have a few hundred hours on Pipers and I have yet to find an airfield where either no flap or flap 25 didn't work.

[Office Update]

Grandad flyer,
just a small point re your post, you can have all the letters from whoever you like but until it becomes part of the POH (flight manual) then its not cosher.

[wobblyprop]

I agree with office. The checkout ride in the archer where i fly specifically goes through the flap settings.

The first stage doesn't really exist and going by the manual is usually pretty smart :)

[Dude~]

Grandad, there are some interesting points made here and I do not disagree with them. However, i do not believe that the POH catagorically says that 10º flaps should not be used, it merely states no precise data for that setting.

If 10º should never be used for take off and provides no advantage for landing then all it serves to do is act as a stepping stone to get to 25º.

Surely, like Cough says, 10º provides a better view particularly if you are trying to hold off the nose wheel on a grass strip. in this case you don't end up doing the last 200 meters of the take off run with much reduced vis.

[BEagle]

So why on earth is there a Flap 10 setting at all? Or is it just to make go-arounds slightly easier when going from Flap 25 to Flap up due to less likelihood of sink??

[This message has been edited by BEagle (edited 10 June 2001).]

[Final 3 Greens]

BEagle

A very good question you ask.

I know that I use F10 in the early stages of the approach, as there is a tendency to pitch up firmly if you go straight to F25, nothing severe, but going through F10 does reduce the effect.

Also, I operate out of a short field, so all take offs are F25 and there is a marked pitch down going from F25 to F10, so I think that your point about go arounds is probably well made.

If one was to fly a take off in a PA28 using the equivalent of a commercial profile, then the F10 setting would be used during the accelerate phase - i.e to increase speed from 65KTS to 70-75ish prior to cleaning the wing and achieving best rate of climb speed.

It is curios though that the POH ingores the F10 setting and I have often wondered why.

Cheers

F3G

['I' in the sky]

Dude.
To answer your 1st question "Why do Piper not provide ......?"
Because it would require the expense of an extra series of performance flight tests.

Q. What performance figures are prospective customers normally interested in ?

A. What is the shortest strip I can get this plane in and out of ?

25 degrees of flap will reduce the minimum safe rotate speed and will therefore reduce the take off ground roll required. Compared to this the take off distance required with 10 degrees will not make the aircraft a more saleable commodity so it is not deemed to be worth investigating.

Back to the practical reality. The difference in rotate speed between 0 and 25 degrees is, off the top of my head about 10 knots, if that so when would you propose to use 10 degrees ?

If the runway length is too short for comfort on 0 degrees then just use 25. If you can comfortably get off the ground with zero, then using 10 will, contrary to popular belief only serve to degrade your climb rate once airborne.