Cessnas with 40 dgree Flaps

[DavidWhite]

My CFI asked me to do a short-field landing today.....he had never flown a skyhawk with 40 of flaps.

"Your high.....your still high"
"No I'm not."
"........."

He couldnt believe I made it in LOL

 

[AEROBAT]

I don't know the fuss about 40 degree flaps, probably more 40 degree Cessnas around than 30 degree. The L-19 has 60 degree flaps.

 

[tonycondon]

i've got a glider that has somewhere north of 60 degrees at full deflection. it makes a 40 degree cessna look like a Nimbus 3. lots of fun having the nose pointed so far down and dropping like a rock!

 

[denverpilot]

I don't know the fuss about 40 degree flaps, probably more 40 degree Cessnas around than 30 degree. The L-19 has 60 degree flaps.

Oooh, I forgot that. My last L-19 ride was well over a decade ago. I need to go find someone who's got one (and is a good stick in it) to demonstrate those...

The last guy I got a ride from was a Vietnam vet... I don't think we ever got more than 200 AGL, and that was in the wing-over to head back toward the airport.

 

[dmccormack]

I don't know the fuss about 40 degree flaps, probably more 40 degree Cessnas around than 30 degree. The L-19 has 60 degree flaps.

Yeah -- so who is "making all the fuss about 40 degree flaps?"



I like them and use full flaps in every airplane I fly all the time unless it's simply unreasonable or unsafe to do so.

My Chief doesn't have flaps so I'm simply forced to aggressively slip.

 

[flyingcheesehead]

My CFI asked me to do a short-field landing today.....he had never flown a skyhawk with 40 of flaps.

"Your high.....your still high"
"No I'm not."
"........."

He couldnt believe I made it in LOL

Hah... Reminds me of Ed (a confirmed Piper pilot) on the radio one year at 6Y9.

"You're never gonna get down from there, Kent..."
"Oh yeah? Watch me."

I love the 40-degree flaps on the 182.

 

[denverpilot]

Me too... with appropriate practice, they can be used for distinctly fun purposes.

Showed a young Commercial pilot that my 182 really could easily get down from 1000' AGL on a 1/4 mile final one afternoon at KFTG. It requires the "dreaded" Cessna slip-with-full-flaps monster.

Nothing in his "ratings mill" college experience had ever shown him that particular edge of a Cessna envelope, which is kinda sad.

But his dad knows it and gets him out with more experienced pilots in as many types as they can beg rides from, since he has an aviation background and understands the difference between 1000 of the same hour, and 1000 real hours of experience.

We both want him to go get some unusual attitude and spin training before he moves away to go play airline somewhere. Neither one of us likes that spins were removed from the curriculum for even professional pilots, let alone us weekend bugsmashers.

 

[Skylane81E]

Me too... with appropriate practice, they can be used for distinctly fun purposes.

Showed a young Commercial pilot that my 182 really could easily get down from 1000' AGL on a 1/4 mile final one afternoon at KFTG. It requires the "dreaded" Cessna slip-with-full-flaps monster.

You know I find the verbage "Avoid slips with flaps extended" in 172 POHs but not in my 182s


So I have no problem with slipping it

 

[Dan Thomas]

You know I find the verbage "Avoid slips with flaps extended" in 172 POHs but not in my 182s


So I have no problem with slipping it

We've been flying 172Ms and a 172S and have slipped with full flaps on all of them for 19 years (3 with the S model) with never a problem. There was supposedly some issue with porpoising when the tail got out of the flap downwash in a slip, but we've never seen it. 172s have a nearly useless slip anyway. Not enough rudder authority. If slipping with flaps was really dangerous Cessna would have said "Slipping prohibited with flaps extended."

Dan

 

[Henning]

Talking with a CFI about a 40deg 182 and he says that 40deg position is employed on short final or short field. Is the elevator still effective or will you stall it? I haven't flown it yet.

It depends where you are in the CG envelope. If you are forward you will need full trim and you may lose some elevator (this is where the old 182s shined with the trimming stab) however your more effective remedy is to keep the 40* flaps and add a couple three inches of power to increase airflow across the elevator, also helps in a crosswind. If you load aft the problem is not as pronounced, but if you do it by adding weight you lose efficiency. Some people still choose to ballast. Regardless, the extra thrust from a couple of inches of power will not overcome the extra drag of 10* more flaps.

 

[Henning]

You know I find the verbage "Avoid slips with flaps extended" in 172 POHs but not in my 182s


So I have no problem with slipping it

Uggg, if that ever wasn't a "Chicken Little" issue.... I would love to know the real background on that one.

 

[Henning]

Me too... with appropriate practice, they can be used for distinctly fun purposes.

Showed a young Commercial pilot that my 182 really could easily get down from 1000' AGL on a 1/4 mile final one afternoon at KFTG. It requires the "dreaded" Cessna slip-with-full-flaps monster.

Nothing in his "ratings mill" college experience had ever shown him that particular edge of a Cessna envelope, which is kinda sad.

But his dad knows it and gets him out with more experienced pilots in as many types as they can beg rides from, since he has an aviation background and understands the difference between 1000 of the same hour, and 1000 real hours of experience.

We both want him to go get some unusual attitude and spin training before he moves away to go play airline somewhere. Neither one of us likes that spins were removed from the curriculum for even professional pilots, let alone us weekend bugsmashers.

Thing is, the slip is NOT the maximum performance angle descent. Try flaps 40 riding the stall buffet straight ahead sometime. You have to time dropping the nose to flare right though or you won't have enough energy. But if you've gotta get in steep and short, that'll get you done best.

 

[dell30rb]

True but it has a place at the best emergency descent configuration. Considering most emergency descents are probably due to fire, a slip at max flap extended speed can help quench flames plus the sideways motion can help you see if there is smoke etc

 

[denverpilot]

Thing is, the slip is NOT the maximum performance angle descent. Try flaps 40 riding the stall buffet straight ahead sometime. You have to time dropping the nose to flare right though or you won't have enough energy. But if you've gotta get in steep and short, that'll get you done best.

Why is that? The skydive and glider tow pilots do that steep nose-high spiral turn thing. Are they also doing it wrong? Or just saving the engine?

I run out of elevator at my stall buffet, power off, but I have a Robertson STOL kit. It'll sit there and bob up and down all day at full up elevator. I'll have to take your word about the increase in descent rate in a normal 182 until I get a chance to try it.

I can't imagine a scenario where I'd need to be quite as steep as you get out of the elevator full-aft and hold it thing in my particular aircraft. That's getting a bit much. Although maybe I do see your descent rate thought, right there. Hmm.

May have to go play with this at altitude and see what our bird does.

Right now I have to drive home from the data center where another lovely Cisco 6509 just cause me what should have never been a trip over here. Port on the bastard just locked up. No changes, nothing. Reprovision an identical port, works fine. Stupid expensive poorly engineered crap...

 

[PilotAlan]

Thing is, the slip is NOT the maximum performance angle descent. Try flaps 40 riding the stall buffet straight ahead sometime. You have to time dropping the nose to flare right though or you won't have enough energy. But if you've gotta get in steep and short, that'll get you done best.

Yep. With Cherokees, when I have to make a steep descent (especially with pax), I'll pop full flaps and slow to about 55-60mph, and get a ~3000fpm descent rate.

It's not the *fastest* descent, but it's the steepest and it's very non-stressful for pax.

 

[Henning]

Why is that? The skydive and glider tow pilots do that steep nose-high spiral turn thing. Are they also doing it wrong? Or just saving the engine?

I run out of elevator at my stall buffet, power off, but I have a Robertson STOL kit. It'll sit there and bob up and down all day at full up elevator. I'll have to take your word about the increase in descent rate in a normal 182 until I get a chance to try it.

I can't imagine a scenario where I'd need to be quite as steep as you get out of the elevator full-aft and hold it thing in my particular aircraft. That's getting a bit much. Although maybe I do see your descent rate thought, right there. Hmm.

May have to go play with this at altitude and see what our bird does.

Right now I have to drive home from the data center where another lovely Cisco 6509 just cause me what should have never been a trip over here. Port on the bastard just locked up. No changes, nothing. Reprovision an identical port, works fine. Stupid expensive poorly engineered crap...

Especially with the R/STOL kit, look at your VSI while you bob around with the power off.

The reason you use it is when you have to stuff into a field shorter than you can make, you can use some gear crush and bounce to absorb some energy.

 

[denverpilot]

Yeah, I'll be looking... never really thought about it before, always assumed that getting the thing all crossed-up was a lot less "efficient" flying than just slowing way up with full flaps. Thus, the bad assumption was, that'd be at least as high a descent rate as the full flap straight-ahead approach.

I was serious about the "Why?" question... what causes that aerodynamically?

I fully believe it, thinking back to the last time I went "bobbing for airspeed" at altitude... but I can't say I've ever directly compared the VSI between the two maneuvers. (Now I want to, of course.)

(I may well wake up in the morning and go... OH, DUH... but right now after messing around with misbehaving network gear, servers, and software all day until 01:20 in the morning, and leaving some messages for some decision-makers that we may have to do a massive system restart with a minor outage, to get some stuff back in sync in the morning... there's no brain cells left capable of thinking about aerodynamics. LOL!)

 

[Skylane81E]

I've done both and ridding the stall down gives the steepest angle of decent, but a beter rate can be achived in other ways.

Now no RSTOL and power off, flaps 40 and full aft elevator makes for an "elevator down" type of ride, nice and smooth but nearly strait down.

 

[Skylane81E]

Uggg, if that ever wasn't a "Chicken Little" issue.... I would love to know the real background on that one.

Some one some where blamed the flaps for a wreck I'm sure.

Cessna probably decided it was cheaper to advise not using slips+flaps.

But then again look at the restart planes, all flaps 30. I kind of understand it on 172s that really can't climb with the barn doors hanging out, but my 182 can, well enough to miss a tree at the end of the runway anyway

 

[Skylane81E]

We've been flying 172Ms and a 172S and have slipped with full flaps on all of them for 19 years (3 with the S model) with never a problem. There was supposedly some issue with porpoising when the tail got out of the flap downwash in a slip, but we've never seen it. 172s have a nearly useless slip anyway. Not enough rudder authority. If slipping with flaps was really dangerous Cessna would have said "Slipping prohibited with flaps extended."

Dan

You know I think I might have slipped an N with full flaps once or twice, been a while sence I spent much time in them

 

[skidoo]

snip ...
But then again look at the restart planes, all flaps 30. I kind of understand it on 172s that really can't climb with the barn doors hanging out, but my 182 can, well enough to miss a tree at the end of the runway anyway

You sure about that? The specs on my 2004 182 show it to have 38 deg flaps. Close enough to 40 for me...

 

[Dan Thomas]

Thing is, the slip is NOT the maximum performance angle descent. Try flaps 40 riding the stall buffet straight ahead sometime. You have to time dropping the nose to flare right though or you won't have enough energy. But if you've gotta get in steep and short, that'll get you done best.

That's what I used to teach in the old Champ. No flaps, and it would slip mightily, but if the student was high he'd want to dive at the runway. That just builds speed that's got to be bled off, usually in ground effect, so the whole tactic is counterproductive. I would demonstrate a high approach and then slow the airplane down by raising the nose. It would sink and end up needing power to make the runway.

To go up, pull back. To come down, pull back more.

Dan

 

[Henning]

Yeah, I'll be looking... never really thought about it before, always assumed that getting the thing all crossed-up was a lot less "efficient" flying than just slowing way up with full flaps. Thus, the bad assumption was, that'd be at least as high a descent rate as the full flap straight-ahead approach.

I was serious about the "Why?" question... what causes that aerodynamically?

I fully believe it, thinking back to the last time I went "bobbing for airspeed" at altitude... but I can't say I've ever directly compared the VSI between the two maneuvers. (Now I want to, of course.)

(I may well wake up in the morning and go... OH, DUH... but right now after messing around with misbehaving network gear, servers, and software all day until 01:20 in the morning, and leaving some messages for some decision-makers that we may have to do a massive system restart with a minor outage, to get some stuff back in sync in the morning... there's no brain cells left capable of thinking about aerodynamics. LOL!)

Think about being at the very back edge of the power curve, can't get no further behind it without stalling, and then having no power except that of gravity.

 

[Henning]

I've done both and ridding the stall down gives the steepest angle of decent, but a beter rate can be achived in other ways.

Now no RSTOL and power off, flaps 40 and full aft elevator makes for an "elevator down" type of ride, nice and smooth but nearly strait down.

Yeah, but every time I do a double Split S or 2 turn spin to the runway, some uptight pr-ck always b-tches about it.....

 

[Henning]

That's what I used to teach in the old Champ. No flaps, and it would slip mightily, but if the student was high he'd want to dive at the runway. That just builds speed that's got to be bled off, usually in ground effect, so the whole tactic is counterproductive. I would demonstrate a high approach and then slow the airplane down by raising the nose. It would sink and end up needing power to make the runway.

To go up, pull back. To come down, pull back more.

Dan

I really learned it flying Ag. Sometimes they send you out with instructions that ain't right lol and you gotta climb to 3000' while looking at the Platte. Sometimes you figure it out and it's close, but when you go diving 2200' with a full tank, you pick up a lot of energy that you don't need and that can get you in trouble, so I'd just pull it back and let it sink to about 500agl and then recover and go in. Problem with slipping into a field is your slosh as you drop in will impart a yawing moment.

 

[jesse]

But then again look at the restart planes, all flaps 30. I kind of understand it on 172s that really can't climb with the barn doors hanging out, but my 182 can, well enough to miss a tree at the end of the runway anyway

The 172P had 30 degrees of flaps, and that happened before the restart. By reducing the flaps they were able to increase the gross weight by 100 lbs which was a good thing since Americans were growing.

 

[Henning]

Here's a basic L/D Max graph. When you are flying at the edge of stall, you are on the left edge of this graph. When you go to slip, you have have to give up AOA to keep from stalling, so you are giving up Induced Drag which is very powerful at this side of the scale and are adding Form Drag which is very weak. That is why it is more efficient to expedite your descent by slowing down than slipping.

 

[Skylane81E]

You sure about that? The specs on my 2004 182 show it to have 38 deg flaps. Close enough to 40 for me...

The one I had the chance to play with was 30 at least I thought it was

 

[Skylane81E]

Yeah, but every time I do a double Split S or 2 turn spin to the runway, some uptight pr-ck always b-tches about it.....

 

[Dan Thomas]

The one I had the chance to play with was 30 at least I thought it was

The TCDS for the 182S lists 38° flaps.

Dan

 

[Skylane81E]

The TCDS for the 182S lists 38° flaps.

Dan

Then it's 38!

 

[skidoo]

Then it's 38!

Yes. I believe the notches are marked as 10, 20, and Full.

 

[denverpilot]

Got it now. Amazing what sleep will do.

 

[Henning]

Yes. I believe the notches are marked as 10, 20, and Full.

Personally I like a momentary flap switch, that way I can fine tune it for exactly what I need for that approach. Sometimes I'll set power way out and tap a little flap and spin a little trim and tap a little flap and spin a little trim... all the way down, just watch and adjust a little and end up at speed, trim and flap just in time.

 

[Dan Thomas]

Personally I like a momentary flap switch, that way I can fine tune it for exactly what I need for that approach. Sometimes I'll set power way out and tap a little flap and spin a little trim and tap a little flap and spin a little trim... all the way down, just watch and adjust a little and end up at speed, trim and flap just in time.

Personally, I prefer manual flaps. Big lever. With that one can haul the airplane off the ground after a really short ground roll (flaps up reduces drag and allows better acceleration) and with manual flaps one can dump them in the flare and get good traction immediately for better braking. The trick is to be right close to the flaps-down stall speed, and when the flaps come up the lift vanishes. Electric flaps are way too slow for any of that.

One of our guys once demonstrated the manual-flaps takeoff in an old 172. Ground roll less than 400 feet, sudden full flap and the thing jumped off the ground. The trick comes in bleeding it off gradually in ground effect so it accelerates without sinking back to the surface.

Of course, I drive a 1951 International pickup with three-on-the-tree and power nothing. Bet some of the young pilots here have never even seen three-on-the-tree or a vehicle without power steering and power brakes and power windows and power seats. Pilots used to all that need electric flaps. No biceps.

Dan

 

[Henning]

Personally, I prefer manual flaps. Big lever. With that one can haul the airplane off the ground after a really short ground roll (flaps up reduces drag and allows better acceleration) and with manual flaps one can dump them in the flare and get good traction immediately for better braking. The trick is to be right close to the flaps-down stall speed, and when the flaps come up the lift vanishes. Electric flaps are way too slow for any of that.

One of our guys once demonstrated the manual-flaps takeoff in an old 172. Ground roll less than 400 feet, sudden full flap and the thing jumped off the ground. The trick comes in bleeding it off gradually in ground effect so it accelerates without sinking back to the surface.

Of course, I drive a 1951 International pickup with three-on-the-tree and power nothing. Bet some of the young pilots here have never even seen three-on-the-tree or a vehicle without power steering and power brakes and power windows and power seats. Pilots used to all that need electric flaps. No biceps.

Dan

The old 182s were even better at it. Those were hard planes to beat, the first few years of the 182. They were some real performers. Thing is with the wheels on the ground and the nose down, the flaps aren't providing lift so they are form drag, and at less than flying speeds, form drag is quite minimal. It's only when you start putting some weight on the wings do they start multiplying on induced drag which is the strong drag at low speed. Flaps work because Lift=Induced Drag. So the real accelerational advantage gained in the "Yank and Pop" method really isn't substantive over just setting the flaps before you take the runway. If there was a substantive advantage to slamming out the flaps, I guaranty that airliners would have them on high speed linear actuators.

 

[dmccormack]

Thing is, the slip is NOT the maximum performance angle descent. Try flaps 40 riding the stall buffet straight ahead sometime. You have to time dropping the nose to flare right though or you won't have enough energy. But if you've gotta get in steep and short, that'll get you done best.

Better yet, slow it up and then slip (with full flaps if ya got 'em). Too often slips are added while still at normal descent speed, lessening the advantage.

 

[Henning]

Better yet, slow it up and then slip (with full flaps if ya got 'em). Too often slips are added while still at normal descent speed, lessening the advantage.

Nope, see my explanation above with the L/D graph. The best you are going to be without being stalled is at buffet straight ahead. Induced drag is much stronger at low speed than form drag.

 

[dmccormack]

Nope, see my explanation above with the L/D graph. The best you are going to be without being stalled is at buffet straight ahead. Induced drag is much stronger at low speed than form drag.

Sure, you can mush it down, but if you're that high and need to drop that steeply, would be faster (and safer) to just go around.

 

[Henning]

Sure, you can mush it down, but if you're that high and need to drop that steeply, would be faster (and safer) to just go around.

It would be "faster" to spiral down as well, but again, you induce greater energies and stresses. You don't need to slow all the way down if you start early, and if you are way out looking at all white PAPI/VASI lights, it's much more comfortable for your passengers if you just slow down to below L/D max and let it sink in. The closer you are when you start the slower you have to go, but as long as the stall horn isn't sounding, the passengers don't know the difference (hell, three pilots on AF 447 didn't know the difference!) and it's more of an airliner feel to them. Passengers don't like crooked airplanes, they don't like steep spiraling turns, they don't like pointing at the ground in a screaming airplane, but you can sit there and sink out of the sky all day with the nose level or a bit high and as long as you act like nothing is happening, they won't know anything is wrong for a long time....

When I first got my multi I flew around with an old guy in his 421 and he go in back and do work he needed to get done. The standard of operation? "Don't spill my drink."