Why does POH not specify full flaps angle?

skidoo

skidoo

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skidoo
I think the early 150's and 172's had flaps marked 10, 20, 30, & 40. I understand that some later models limited the max flap setting to 30 deg. My 182 has three notches; 10, 20, and Full. It doesn't state in the POH what full is. I had assumed that it would be 30. But, after looking at the maintenance manual, I saw it stated that full was at 38 degrees. That was a pleasant surprise. Concerned it may be a typo, I went out and confirmed it was indeed 38 degrees. Nice! So, does anyone know why the actual angle isn't stated in the POH. Just Curious.
 
skidoo said:
I think the early 150's and 172's had flaps marked 10, 20, 30, & 40. I understand that some later models limited the max flap setting to 30 deg. My 182 has three notches; 10, 20, and Full. It doesn't state in the POH what full is. I had assumed that it would be 30. But, after looking at the maintenance manual, I saw it stated that full was at 38 degrees. That was a pleasant surprise. Concerned it may be a typo, I went out and confirmed it was indeed 38 degrees. Nice! So, does anyone know why the actual angle isn't stated in the POH. Just Curious.
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Same reason that aileron and elevator angle is not mentioned, nor is flap deflection. For the pilot that's really not useful information.
 
gismo said:
But if you really want to know it's in the TCDS:

http://tinyurl.com/Cessna182-TCDS
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:redface: Darn, I keep forgetting about that document. It seems to have just about everything you want to know. Looks like all of the 182 models had 40 deg flaps until the S and T versions with 38 deg. Somehow I was erroneously thinking the change in 172s also applied.
 
skidoo said:
Somehow I was erroneously thinking the change in 172s also applied.
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They were counting on that. Someone in Marketing figured (probably correctly so) that 'Full' wouldn't scare you and give cause for a libel suit if you make a bouncy landing with all those flaps. Isn't that why they they reduced the flaps in the 152/172's?
 
nosehair said:
They were counting on that. Someone in Marketing figured (probably correctly so) that 'Full' wouldn't scare you and give cause for a libel suit if you make a bouncy landing with all those flaps. Isn't that why they they reduced the flaps in the 152/172's?
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No, that was because of a GW increase. At the higher weight the airplane couldn't meet the balked full flap landing requirements with 40° flaps.
 
gismo said:
the airplane couldn't meet the balked full flap landing requirements with 40° flaps.
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?? Oh? Well, I was really kidding, but I did think that libel suits accounted for some of the design change.

This is the first I've heard of a factual aerodynamic reason. Can you expand or reference some other details on this? I really could use it to help me get away from my attitude that so much of the modern aircraft design features are politically motivated. Thanks.
 
nosehair said:
?? Oh? Well, I was really kidding, but I did think that libel suits accounted for some of the design change.

This is the first I've heard of a factual aerodynamic reason. Can you expand or reference some other details on this? I really could use it to help me get away from my attitude that so much of the modern aircraft design features are politically motivated. Thanks.
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Look at the 172 manual for the last year that it was 40 degrees and the first year that it was 30 degrees. You'll see that gross weight increased 100 lbs when they went to 30 degrees.

After that, read the certification requirements, and it becomes pretty obvious.
 
jesse said:
Look at the 172 manual for the last year that it was 40 degrees and the first year that it was 30 degrees. You'll see that gross weight increased 100 lbs when they went to 30 degrees.

After that, read the certification requirements, and it becomes pretty obvious.
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not to mention the STC for 40 deg flap 172s that allow a 100 lb gross weight increase if you limit the flap travel to 30 deg.
 
nosehair said:
This is the first I've heard of a factual aerodynamic reason. Can you expand or reference some other details on this? I really could use it to help me get away from my attitude that so much of the modern aircraft design features are politically motivated. Thanks.
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It's not in anything Cessna published publicly, but the flap reduction and GW increase came together, there's an STC to increase GW 100 lb for the 2300-lb 172's by replacing the flap switch with one that limits flaps to 30 degrees, there were no structural or power changes made to the plane, and there's a full-flap/MGW balked landing requirement in the certification rules. Considering all information, it seems to follow that the GW increase was allowed by the flap decrease.
 
Ron Levy said:
...there's a full-flap/MGW balked landing requirement in the certification rules. Considering all information, it seems to follow that the GW increase was allowed by the flap decrease.
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As an aside, out here in the summer, my CFI limited me to 30* flaps on final, a 150hp Skyhawk has some pretty lousy go-around performance when the density altitude is 9000ft.
With full flaps, you may just hit the ground before the climb is established.

Coming from Florida, that was my first introduction to the difference bwtween sea-level flying and high-DA flying.
 
PilotAlan said:
As an aside, out here in the summer, my CFI limited me to 30* flaps on final, a 150hp Skyhawk has some pretty lousy go-around performance when the density altitude is 9000ft.
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Does your instructor also recommend not raising the gear on a retractable plane just because it might not extend again? Even with 30 flaps, you don't have any go-around at 9000 DA in a 150HP 172 unless you're really light. Better to use full flaps and make a good landing because the landing always has to be made eventually, but with 30 flaps, you end up using more runway because the flaps might fail during an unanticipated go-around.
 
Ron Levy said:
Does your instructor also recommend not raising the gear on a retractable plane just because it might not extend again? Even with 30 flaps, you don't have any go-around at 9000 DA in a 150HP 172 unless you're really light. Better to use full flaps and make a good landing because the landing always has to be made eventually, but with 30 flaps, you end up using more runway because the flaps might fail during an unanticipated go-around.
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Before you start attacking instructors at high density altitude airports for some their acquired modifications to sea-level operating procedures, you ought to try a couple of them.

I don't necessarily agree with this one but I can see why a pilot might consider limiting the amount a travel that the flaps have to do to get to the go-around setting for a 110 HP 172 (loss of about 3% HP per 1000' density altitude) on an 8000' runway quite a bit of which you may have already used up because of higher TAS and GS, and where you'd like to climb to a safe turning altitude before you bust the Class B surface area less than a mile off the end of the runway.
 
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Simple, I just never use the 40* setting on the flap switch: no STC's, no balked landing issues....the balked landing performance going from 40* to 30* is really dismal compared to going from 30* to 20*.....ask me how I know!!!
 
DutchessFlier said:
Simple, I just never use the 40* setting on the flap switch: no STC's, no balked landing issues....the balked landing performance going from 40* to 30* is really dismal compared to going from 30* to 20*.....ask me how I know!!!
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I always used 40 degrees of flaps on your 172. Preferred landing that way - but that's just me.

I was just looking in my logbook - the last time I flew your 172 was 1/1/2006. I had flown it to Des Moines Iowa from Rochester Minnesota on 12/23 but the weather went IFR and I had to take a bus home. I went back to DSM on 1/1/2006 and flew it back to Minnesota.

My first demo flight was also done in your airplane. Didn't fly it a whole lot though, about 10 hours total.

I think I paid about $75 / hr wet for it. Wish I could still fly it for that :)
 
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jesse said:
I always used 40 degrees of flaps on your 172. Preferred landing that way - but that's just me.

I was just looking in my logbook - the last time I flew your 172 was 1/1/2006. I had flown it to Des Moines Iowa from Rochester Minnesota on 12/23 but the weather went IFR and I had to take a bus home. I went back to DSM on 1/1/2006 and flew it back to Minnesota.

My first demo flight was also done in your airplane. Didn't fly it a whole lot though, about 10 hours total.

I think I paid about $75 / hr wet for it. Wish I could still fly it for that :)
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So do I and I own the danged thing :D Lease rate right now is $90 with a $13/hr fuel surcharge.

I began learning in a different 172 that only had 30* max flap setting, so I got used to that, most folks have their own preferences, but alot have done the STC to stop the flap travel at 30*. I won't do that.

You just want me to fly back out to MN and get you in 71D again! Hey, anytime you want to meet up let me know, you are more than welcome to revisit the plane and fly it again.

Jesse, was the plane painted and the interior replaced when you flew it?

I've got about 175 hrs in 71D right now...the plane has put about 300 hours on since last May.
 
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