Cessna's recommendation on flaps

[Aye Effaar]

So I went flying a 172s with another pilot this weekend. It was a 2008 SP model.

I noticed the other pilot used flaps-10 on every takeoff. I didn’t think much about it, but he also didn’t cleanup until 700 AGL. When I asked why – he said his instructor had recommended this. Later, during a descent 8 miles away from the airport, he put in flaps-10. Again, he said his instructor had advised.

I'd been flying S models for years and never seen this. And I've never had an instructor recommend this either. I checked the POH to see where this idea might have come from.

I was surprised to discover Cessna now recommends flaps-10, even for a normal takeoff, and to only retract at a “safe altitude”. A check of descent procedures leaves flaps to pilots discretion, but since they mention flaps in the checklist – it’s easy to see where someone would consider during descent normal.

Just wondering what other S drivers are doing?

 

[WDD]

I've never heard of this, and I've flown a few SP's here and there. 10% flaps on take off only for short field is what I'm used to. But I can't see the harm, and if it's in that plane's POH, then sure.

As far as decent, as long as you're below Vfe not going to harm anything, and on IFR you go to 10% flaps at FAF - so there's that. I don't do any flaps VFR until I'm on downwind FWIW.

 

[ktup-flyer]

I don’t even put flaps in in the 182 until 3-4nm out, unless I’m shooting an approach. They’re not difficult to slow down. I always take off with flaps though.

I don’t remember taking off with flaps in the 172

 

[Stewartb]

Takeoff 20° flaps for all but very soft or short, then 30°. Landing I don’t add any flaps until slowed to <90mph on downwind. All landings with full flaps.

 

[dmspilot]

I was surprised to discover Cessna now recommends flaps-10, even for a normal takeoff, and to only retract at a “safe altitude”.

Seems to be specific to the NAV III model. It does fly a bit different, owing to the higher empty weight and a different weight distribution than the conventional model.

 

[Aye Effaar]

Takeoff 20° flaps for all but very soft or short, then 30°. Landing I don’t add any flaps until slowed to <90mph on downwind. All landings with full flaps.

You take off in a 172 with flaps-30 ?

 

[Pilawt]

You take off in a 172 with flaps-30 ?

Any flap extension beyond 20° in a 172 is pure drag, no additional lift.

 

[Busflyer]

Takeoff 20° flaps for all but very soft or short, then 30°. Landing I don’t add any flaps until slowed to <90mph on downwind. All landings with full flaps.

Seriously?

 

[TommyG]

Flaps create lift. No harm in putting 10 degrees in for takeoff. I know a guy keep the 10 degrees until 3k feet.

 

[Stewartb]

In my old Hawk XP, yes, seriously. I recall my float check ride in that plane. The DPE demonstrated 40* flap landings onto a short lake surrounded by tall trees. I mentioned the placard said 30* maximum. He said 40* works better. He was right. Every float pilot I know uses 20* for the takeoff run and bumps it to 30* to break the water. Some use it momentarily, some leave it alone for initial climb out.

I use the same flap settings in my 180, as well. Sometimes in the 180 I practice takeoffs with flaps 40. Amazing performance but requires adequate power.

 

[benyflyguy]

I don’t even put flaps in in the 182 until 3-4nm out, unless I’m shooting an approach. They’re not difficult to slow down. I always take off with flaps though.

I don’t remember taking off with flaps in the 172

Same here in a 182H. Approach before FAF, if VFR beam the numbers. Always on take off. Rarely 40 degree unless super short runway or practicing it

 

[DavidWhite]

In my old Hawk XP, yes, seriously. I recall my float check ride in that plane. The DPE demonstrated 40* flap landings onto a short lake surrounded by tall trees. I mentioned the placard said 30* maximum. He said 40* works better. He was right. Every float pilot I know uses 20* for the takeoff run and bumps it to 30* to break the water. Some use it momentarily, some leave it alone for initial climb out.

I use the same flap settings in my 180, as well. Sometimes in the 180 I practice takeoffs with flaps 40. Amazing performance but requires adequate power.

Cue all the “experts” here who’ve never landed on anything shorter than 2500’ telling you you’re wrong.

 

[luvflyin]

In my old Hawk XP, yes, seriously. I recall my float check ride in that plane. The DPE demonstrated 40* flap landings onto a short lake surrounded by tall trees. I mentioned the placard said 30* maximum. He said 40* works better. He was right. Every float pilot I know uses 20* for the takeoff run and bumps it to 30* to break the water. Some use it momentarily, some leave it alone for initial climb out.

I use the same flap settings in my 180, as well. Sometimes in the 180 I practice takeoffs with flaps 40. Amazing performance but requires adequate power.

I’m sure there’s other float specific things also. On the 180, I’m wondering how launching with 40 would effect loss of engine on take off procedure. In some situations, I could see it maybe not being a bad thing.

 

[asicer]

Just wondering what other S drivers are doing?

As I recall, the POH said it gets the weight off the asphalt sooner but doesn't make any overall difference.

Seems to be specific to the NAV III model. It does fly a bit different, owing to the higher empty weight and a different weight distribution than the conventional model.

I think it was specific to the 180hp. I'll have to check my 172R POH when I get a chance.

 

[Pilawt]

Cessna did not recommend extended flaps for normal takeoffs in the earlier, lower-powered 172 models because although ground run was shorter with 10° of flap, the advantage was lost in the climb over a 50' obstacle. With 180 hp and above the equation shifts a little bit. Cessna now says 10° on takeoff is "preferred", but in boldface type the manual says anything more than 10° is "not approved for takeoff."



By contrast, my PA-32-300 is a high-powered airplane with small flaps. I know PA-32 pilots who keep 10° flap extended after takeoff all the way up to cruising altitude.

Bottom line, use of takeoff flaps is type-specific - read the manual and understand the reason for the recommendations and limitations. "My CFI did it that way" is not enough.

I think it was specific to the 180hp. I'll have to check my 172R POH when I get a chance.

I just looked at both the 172R and 172S manuals - the text for both appears the same regarding takeoff flaps, except obstacle clearance speed is a knot higher for the 172R.

 

[asicer]

I just looked at both the 172R and 172S manuals - the text for both appears the same regarding takeoff flaps, except obstacle clearance speed is a knot higher for the 172R.

Hm, weird given that the R is supposed to have the same horsepower as the N and P (albeit at lower RPM).

 

[dmspilot]

I think it was specific to the 180hp. I'll have to check my 172R POH when I get a chance.

I already checked. The NAV III model states 10° is "preferred". The others do not.

 

[Stewartb]

I’m sure there’s other float specific things also. On the 180, I’m wondering how launching with 40 would effect loss of engine on take off procedure. In some situations, I could see it maybe not being a bad thing.

Power loss in that configuration wouldn't turn out well. Using 40* for takeoff is mostly a training exercise for going around in crappy conditions on a short strip when you don't have time or space to milk off the flaps.

 

[aftCG]

Ten degrees flaps when 8 miles out, really? Someone worried about how slippery the mighty C172 is?

I don't see any use for them until midfield down wind but okay

 

[Bonchie]

We have S models and I’ve always just taught no flaps for a normal takeoff because that’s what all the other 172s and 182s I’ve flown took.

We use the POH checklists and they say 0-10 degrees for normal takeoff. I figured why add the extra step for students if it’s not a short field and necessary? Climbs great no flaps anyway.

If it’s an option, I say do what you find best.

 

[asicer]

I already checked. The NAV III model states 10° is "preferred". The others do not.

Actually, looks like it's the same text from the P onwards in the amplified section. Here's what the N says:




And from left to right, the P, R, NAV I/II SP, NAV III SP (they all say the same thing word for word):



Not sure why the abbreviated section is different. Maybe it just evolved over time?

 

[dmspilot]

And from left to right, the P, R, NAV I/II SP, NAV III SP (they all say the same thing word for word):

I'm referring to this:

 

[asicer]

I'm referring to this:

View attachment 108227

Yup. Like I said: not sure why the amplified section is word for word while the abbreviated section is different, other than perhaps there was some evolution over time.

 

[IK04]

Back in the pre-POH days, we would extend the flaps until they lined up with the trailing edge of a fully lowered aileron.

That worked well for short and soft field takeoffs.

 

[Daleandee]

Back in the pre-POH days, we would extend the flaps until they lined up with the trailing edge of a fully lowered aileron.

Isn't that the best setting for lift to drag?

 

[Stewartb]

Fast taxi a Cessna at 20° flaps and hold it just below flying speed. Apply full flaps? You’re flying. Conversely, that’s why short field guys dump flaps on touchdown.

 

[Busflyer]

In my old Hawk XP, yes, seriously. I recall my float check ride in that plane. The DPE demonstrated 40* flap landings onto a short lake surrounded by tall trees. I mentioned the placard said 30* maximum. He said 40* works better. He was right. Every float pilot I know uses 20* for the takeoff run and bumps it to 30* to break the water. Some use it momentarily, some leave it alone for initial climb out.

I use the same flap settings in my 180, as well. Sometimes in the 180 I practice takeoffs with flaps 40. Amazing performance but requires adequate power.

If you were referring to float flying in your original post then I’ll defer to you. I have no experience with that but if you’re referring to grass/hard surfaces then that just seems like a lot of extra drag.

 

[RyanB]

Full flaps at 10 miles out is the best procedure in the 172.

 

[Sierra_Hotel]

Full flaps at 10 miles out is the best procedure in the 172.

 

[MauleSkinner]

Full flaps at 10 miles out is the best procedure in the 172.

How else,are you supposed to fly a stabilized approach?

 

[WWFeldman]

Full flaps at 10 miles out is the best procedure in the 172.

Does that include my 40 degree flaps? I might never get there.

 

[RyanB]

Does that include my 40 degree flaps? I might never get there.

Whatever you’ve got - use ‘em all!

 

[bflynn]

2005 172S, no flaps on takeoff. Flaps start in 10 degrees abeam the numbers, 20 degrees on base. My POH says 20 degrees is the final flaps configuration for landing.

 

[RyanB]

POH says 20 degrees is the final flaps configuration for landing.

What’s the last notch (30deg) for then?

 

[bflynn]

What’s the last notch (30deg) for then?

That is an excellent question.

 

[Sac Arrow]

I don't get the point of using flaps on takeoff other than a short or sort field, short of an airliner. The DA40 I had some hours in had one notch of flaps as standard on takeoff. The CFI that checked me out thought it was pointless. I thought it was pointless. I did it both ways. It didn't seem to make any difference on takeoff performance either way, except that the flaps hurt climb performance.

 

[dmspilot]

2005 172S, no flaps on takeoff. Flaps start in 10 degrees abeam the numbers, 20 degrees on base. My POH says 20 degrees is the final flaps configuration for landing.

On what page does it say that?

 

[asicer]

2005 172S, no flaps on takeoff. Flaps start in 10 degrees abeam the numbers, 20 degrees on base. My POH says 20 degrees is the final flaps configuration for landing.

Does your POH say something different than in post #21?

 

[bflynn]

The airplane is 45 minutes away, but thanks to some idiot on American last week, I’m quarantining right now. it will be a while before I could go take a picture. However, I have a very clear memory of no flaps on takeoff and only 20 degrees for landings.

 

[kaiser]

I don't get the point of using flaps on takeoff other than a short or sort field, short of an airliner. The DA40 I had some hours in had one notch of flaps as standard on takeoff. The CFI that checked me out thought it was pointless. I thought it was pointless. I did it both ways. It didn't seem to make any difference on takeoff performance either way, except that the flaps hurt climb performance.

Really? I did touch and gos with a CFI in a DA40 and on one go we (it was him but I’m PIC, so “we”) commanded flaps up. I felt like the takeoff roll was double! Took ages to get off the ground.

In general regarding flaps on take off, I heard of an unofficial study* where you trade shorter take off ground roll for something like 100-150 fewer fpm.

*Bunch of guys took a 182 and measured performance in various configs