Full flap takeoffs: why not?

[Skookum]

Removed

[. ._]

BTW anybody got a 172 POH with the float plane supplement? I'd be interested to see what it says about flap selection. Just out of curiosity of course.

For the 1969 supplement I have it says 10 degrees for take offs.

To shorten the take off run, it recommends allowing "airspeed to build to 40mph, at which speed one float can be raised out of the water by slowly applying full aileron".

There could be a whole thread in itself debating the whole "one float vs. 20 degrees of flap".

-istp

[mellow_pilot]

There is no rule that says you can't fly below 500 feet. If there was, all the training schools doing practise forced approaches would be breaking the law.
CAR 602.14(1) states that you cannot fly "at a distance less than 500 feet from any person, vessel, vehicle or structure." Other rules apply in controlled airspace and in built-up areas, but elsewhere you can fly as low as you want as long as you're 500 feet away from any object.

I realise this, but there is always the argument (however anal it amy be) that powerlines, fences, roads, etc count as objects/property/'built up". I'm not sure I would agree with that definition, but I wouldn't want to have to argue it at a tribunal.

I was trying to present a generic example, not argue CAR semantics.

[justplanecrazy]

BTW anybody got a 172 POH with the float plane supplement? I'd be interested to see what it says about flap selection. Just out of curiosity of course.

For the 1969 supplement I have it says 10 degrees for take offs.

To shorten the take off run, it recommends allowing "airspeed to build to 40mph, at which speed one float can be raised out of the water by slowly applying full aileron".

There could be a whole thread in itself debating the whole "one float vs. 20 degrees of flap".

-istp

We've gone from flaps, to TC, to mudslinging, to amending the training forum, to min. altitudes, we might as well throw in a few 1 vs. 2 float comments. I won't be the one to do that though, well not in depth anyways. ISTP can you please clear up all this crap seeing as you have access to a c172 POH. Please quote all the comments relating to 10 degrees of flaps on take-off and what section they fall under. Does it say, never use more than 10 degrees of flaps on take-off? Does it say anything about this in the limitations section? Or does it simply say use up to 10 degrees flaps for short field take-off, at 40mph, lift a float etc.?

It's funny that it states lift a float cause like you said that's a very debatable subject. In fact the only time its really considered a significant advantage or an advantage at all, is during glassy water, max gross, or high density altitude. Yet it doesn't happen to mention any of the other tricks like rocking on to the step. So if you follow the ridiculous train of thought mentioned in this thread, if you want a shorter run, thou shall use the one float take off.

[Hedley]

FWIW I have a 1975 C172 "Owner's Manual" on my desk (I have the misfortune to have instructed around 1000 hours in various C172) and Section II, "Description and Operating Details" on page 2-14 in the paragraph titled "Wing Flap Settings" it says:

Flap settings greater than 10 degrees are not recommended at any time for takeoff

Now, if I flip forward to Section IV, "Operating Limitations", nowhere does it mention the subject of flaps and takeoffs.

Therefore, one could conclude that the C of A was still valid with a 20 degree flap takeoff, because the aircraft is not being operated contrary to the operating limitations in the manual or placards.

Go back and re-read carefully what Cessna says about flaps and takeoff. All they're saying is that they're not promoting flaps with more than 10 degrees of flaps for takeoff.

Really, this should be covered in the float STC addendum to the manual.

[. ._]

justplanecrazy,

I don't have time to quote the POH today, but I looked up some more stuff.

For the 1969 Cessna 172, the POH mentions only 10 degrees on take off in the Description and Operating Details section. There are "shoulds" but no "musts".

The Operating Limitations are the same as the land plane- where the word "flap" never appears.

It may be different in later models' POHs, as I think they're a bit more in depth.

In the land plane POH part, all takeoff checklists are with 0 degrees flap- including short-field takeoffs. But again, there's no "the pilot will crash and die if other flap settings are used" mentioned.

So it seems to me, that like many things in aviation, it's ambiguous as to what's legal, safe, recommended or efficient when it comes to flap operation on take off.

-istp

[groupboard]

I realise this, but there is always the argument (however anal it amy be) that powerlines, fences, roads, etc count as objects/property/'built up". I'm not sure I would agree with that definition, but I wouldn't want to have to argue it at a tribunal.

I'm not sure if a powerline counts as a structure (I would imagine it does), but powerlines are one of the main reasons why it's a bad idea to fly low unless you know what you're doing. There are a lot of accident reports of dozy pilots flying 50 feet above the surface of a reservoir (or similar), and then hit the powerlines because they haven't been looking out for them.

[justplanecrazy]

FWIW I have a 1975 C172 "Owner's Manual" on my desk (I have the misfortune to have instructed around 1000 hours in various C172) and Section II, "Description and Operating Details" on page 2-14 in the paragraph titled "Wing Flap Settings" it says:

Flap settings greater than 10 degrees are not recommended at any time for takeoff

Now, if I flip forward to Section IV, "Operating Limitations", nowhere does it mention the subject of flaps and takeoffs.

Therefore, one could conclude that the C of A was still valid with a 20 degree flap takeoff, because the aircraft is not being operated contrary to the operating limitations in the manual or placards.

Thank-you Hedley. Hopefully this thread will curl up and die now!!!!!!

So in conclusion (hopefully), teach the student how to do a 20 degree flap take-off or even 40 and tell him when and where you would use this, what the dangers are in using it, and how the aircraft will handle when doing it. Then on the pre-flight test tell the student that TC wants to see that you can fly the plane by the POH's recommondations. At no point can TC or anyone shut you down for teaching 20 degrees or even full flap take offs as there are no regulations against it. They may dock you marks on the ride because they want to see you following the recomondations of the POH. According to Cessna themselves, anything outside of the limitations and weight and balance section of the POH are simply recomondations and to go against them, does not void the airworthiness certificate!!!!

[CD]

I'm not sure if a powerline counts as a structure (I would imagine it does), but powerlines are one of the main reasons why it's a bad idea to fly low unless you know what you're doing. There are a lot of accident reports of dozy pilots flying 50 feet above the surface of a reservoir (or similar), and then hit the powerlines because they haven't been looking out for them.

Cows as well... I've got some great photos around here somewhere of a 172 rolled up into a ball near YQF after having a near-ground collision with a bovine.

[tailwind]

In the C185 I flew this summer, it was equipped with the Robertson Stol Kit and in the supplement for it is stated for short field take-offs, Start the takeoff run with 20 degrees of flap, once on the step (floats obviously).. move flaps to 30 to become airborne quicker...drop flaps in stages with safe airspeeeds for climbout.

This worked great and even helped to get on the step when you were almost there.

[co-joe]

Hunh. Page 6 actually got interesting once the flames stopped. I learned a thing or two here. Thanks boys.

[youngflier]

lift to drag ratio is considerably smaller with full flaps