The 40 Degree Flap Question

Idriveplane · Post by **Idriveplane** » Thu Mar 15, 2007 3:25 pm

How come manufactures like cessna etc got rid of 40 flap? I've also been flying the new Found quite abit and there are times I wish I had a lil more than 30. Was it for go around performance? Liability?

highlander · Post by **highlander** » Thu Mar 15, 2007 4:38 pm

An old edition of flying magazine that talked about used aircraft mentioned that C-182's with 40 degrees of flap had or have a history of damage to the firewall that is connected to the pilot's use of 40 flap. I don't remember the specifics as to why but I imagine that the "excess drag and harder landings?"

West Coast Swell · Post by **West Coast Swell** » Thu Mar 15, 2007 4:50 pm

Why do you feel you need more than 30 flap? I take it that desire is on landing right. But what will more flap do for you?

xsbank · Post by **xsbank** » Thu Mar 15, 2007 6:08 pm

Ever used 'landing flap' on a Beav? You're not supposed to, but its quite useful. The old manual flap 172s were great (partly to do with the old wing).

Can never have too much flap!

zero · Post by **zero** » Thu Mar 15, 2007 6:54 pm

Why not use 'landing flap' on the -2?

xsbank · Post by **xsbank** » Thu Mar 15, 2007 7:28 pm

Limitations? Placard? Someone quote a manual for me - I haven't Beaved for 5 or more years now.

Falken · Post by **Falken** » Thu Mar 15, 2007 7:29 pm

From what I've heard / read:

40 deg of flap can disrupt the air flow running towards the tailplane so much during a slip, that as the aircraft slows down (ie on final in a crosswind), it can create a tailplane stall. Now, we all know the tail just holds the nose up.. without it, you find yourself a good 30-45 degrees nose down on short final. Apparently, it recovers quite quickly... hopefully fast enough.

I've flown a C150 with the old 40 degree flap configuration. I've never had the above happen to me, but the story sure did make me nervous on the occasions while using full flap on landing.

One thing to add... dont forget about the fun you'll have on an overshoot if you try to pull a loaded 150 into a climb and forget 40 degrees of pure speed-brakes.

Edo · Post by **Edo** » Thu Mar 15, 2007 7:42 pm

zero - landing flap on the beaver is quite a bit of flap, you need lots of power and she drags in.

normally, you use just a bit more than takeoff

YACdirect · Post by **YACdirect** » Thu Mar 15, 2007 8:59 pm

zero wrote:Why not use 'landing flap' on the -2?

"The use of full flap is restricted to emergency landings in restricted areas" - from the DHC2 manual although it may not be word for word since I am not reading it at the moment.

To my understanding full flap can cause severe elevator ineffectiveness. I recall a finding from the Pickerel Arm crash was that the pilot was using full flap - turn - stall... RIP guys.

Heard of many other -2's suffering massively hard landings because the elevators couldn't raise the nose when it got to the water... descent attitude and regular descent rate on touchdown? Ouch! Float fittings punched through floors, bent floats, etc.

I like to 40 flap setting in the 206 - really helpful in slowing right down, especially in making the landings on the ice runway in YXL that we do. In contrast, the 210 only runs flap down to 30 degrees and I notice a huge difference - it doesn't have the same "stopping power" in the air if you know what I mean. Speeds are higher and descent angle shallower making that landing over Mascotto's big tree a little more challenging. Truth be told the 206 and 210 have very different wing designs so it is hard to compare the two, but I definitely notice the difference.

The use of flap on the 206 on floats is restricted to 30; presumably for the same reasons as mentioned. I have done it with 40 and it seems to handle alright but it sure comes down quick and you have to be on top of it.

Finally, the DHC-3T with Garrets I believe still have Otter flaps (don't know the angle) but the PT6 powered -3T's have restricted flaps for landing. I believe that one has something to do with the time it takes a PT6 to spool up to fix a "holy crap are we ever descending fast" situation or during a go-around where a Garrett is already "there"

golden hawk · Post by **golden hawk** » Thu Mar 15, 2007 10:26 pm

Full flap on a Twin Otter - interesting!!!

Hoov · Post by **Hoov** » Thu Mar 15, 2007 11:12 pm

I am no expert believe you me, but I do think your safe using full flap on your 150 there.

bugspray · Post by **bugspray** » Thu Mar 15, 2007 11:34 pm

"Why do you feel you need more than 30 flap? I take it that desire is on landing right. But what will more flap do for you?"

Obviously you have never done any STOL work. The DHC family was developed on STOL performance. In the flat lands with big lakes one would wonder what its needed for. Land at high elevations, in the mountains on hot summer days, and you will know exactly what the full flap is all about. Full flap is what makes the DeHavilland. Taking it away fromt any aircraft decreases its performance considerably. It was as huge mistake taking the full flap capability away from the PT6 DHC-3.
Its quite simple. Full flap reduces your approach and stall speed therefore reduces your landing role. . I dont know why so few don't understand this.
There is nothing wrong with full flap landings.. Thats what full flap was designed for.
Incompetent flying abilites is what creates these restricted flap landings, is nothing more.

Idriveplane · Post by **Idriveplane** » Fri Mar 16, 2007 4:35 am

Why do you feel you need more than 30 flap

I was going to say, because we operate off a 1700' ice runway with a rather steep approach over trees/power lines etc when going in one way. The 185 I fly has the ol handle bar and 40 flap which is just peachy, wish the found had that.

PT6-114A · Post by **PT6-114A** » Fri Mar 16, 2007 8:00 am

.

I am no expert believe you me, but I do think your safe using full flap on your 150 there

what is wrong with using full flap that is why they put it there.

Rudder Bug · Post by **Rudder Bug** » Fri Mar 16, 2007 8:59 am

A Beaver with full flaps can be a touchy aircraft for a newbe or in choppy conditions. I usually consider 40 degree to plenty for "normal landing".

However, the option of using more flaps is there, and to be used with caution in some exceptional circumstances that STOL plane was designed for.

They happened to label this position Landing. Was this to sell the plane, like many other POH? Perhaps cause it can make it more spectacular.

One should practice some full flaps go arounds at altitude. The drastically reduced aileron/elevator authorithy can be surprising and the aircraft, once in this configuration, is not as easy to control as most people would think.

CLguy · Post by **CLguy** » Fri Mar 16, 2007 9:57 am

Golden hawk wrote:

Full flap on a Twin Otter - interesting!!!

I only have a few hundred hours on a Twin Otter but the only non full flap landings I have ever done with it was in training when we did a couple of zero flap landings. Care to elaborate because I obviously missed something.

ODA · Post by **ODA** » Fri Mar 16, 2007 10:53 am

Sometimes when aircraft gross weights are increased you have to use less flap. On a Turbo Beaver with an upgross kit the flaps can only go to landing not full. The early cesna 172's had 40 flap until they had an upgross and then they only had 30.
I guess it keeps the same wing loading or something with less flap and more weight.

Hoov · Post by **Hoov** » Fri Mar 16, 2007 11:45 am

PT6-114A wrote:.
I am no expert believe you me, but I do think your safe using full flap on your 150 there

what is wrong with using full flap that is why they put it there.

Uh that was kind of my point.

Cat Driver · Post by **Cat Driver** » Fri Mar 16, 2007 2:34 pm

Maybe this discomfort with using full faps on a certified aircraft is a culture thing....

...you know something instilled by the 5 knot maximum X/wind crowd?

A Canadian flight training thing???

Maybe this is another product of the dumb e'm down crowd ?

SQ · Post by SQ » Fri Mar 16, 2007 3:34 pm

Rudder Bug wrote: One should practice some full flaps go arounds at altitude. The drastically reduced aileron/elevator authorithy can be surprising and the aircraft, once in this configuration, is not as easy to control as most people would think.

Good point
when I was praticing precautionnnary landings I had fex difficulties to gain speed to climb as I was pushing hard on the stick to keep a correct angle of climb before a nose up stall. trim ? drag ? Both ?
What is touchy, and may be the experienced guy will bring their advice, I didn't feel comfortable to reduce flaps of 20° and did a 10° correction. altitude was 100' AGL and I also gain ground effect.
question : in a go around at very law altitude, 40° flaps can be a pain in the **s, reduce them: a new way to encounter ground.
so ?

Rudder Bug · Post by **Rudder Bug** » Fri Mar 16, 2007 7:12 pm

SQ you must be talking about a Cessna. Everything exceeding 20 degrees is no lift but only drag and on a go around this is the first thing you have to get rid of. You won't plummet raising the flaps from 40 to 20 with full power, you'll gain speed, hence altitude.

xsbank · Post by **xsbank** » Fri Mar 16, 2007 7:12 pm

Go around - decide and make the call
Check thrust - set take-off or meto (even a Stoneboat will go up at full flap and meto power)
Flaps - reduce as per POH
Positive rate - +VSI
Gear up
Follow the published miss or departure

Rowdy · Post by **Rowdy** » Fri Mar 16, 2007 8:19 pm

sorry to go offtopic.. but why do they call a piston otter a stoneboat.. and a turbine one a swine?

YACdirect · Post by **YACdirect** » Fri Mar 16, 2007 8:25 pm

Idriveplane wrote:
Why do you feel you need more than 30 flap
I was going to say, because we operate off a 1700' ice runway with a rather steep approach over trees/power lines etc when going in one way. The 185 I fly has the ol handle bar and 40 flap which is just peachy, wish the found had that.

You think it's 1700 feet? I'm sure it's gotta be shorter than that... 1500?We should go out there and pace it someday we're bored

Edit: I stand corrected - it's 1800 on Google Earth this year, last year and the year before 1500 & 1600 or so. Seems awfully short eh? I don't recall if you were around last year but it is a good 10 feet wider this year.

twotter · Post by **twotter** » Sat Mar 17, 2007 2:33 am

Rowdy wrote:sorry to go offtopic.. but why do they call a piston otter a stoneboat.. and a turbine one a swine?

Years ago we did call the piston otter a swine.. But now it has such a rhyming sound when you say that it is a turbine swine..

I think it was a stoneboat out east but a swine in the west..