Flaps and Carb Heat on Landing Rollout

Tantalum said:
Has a plane ever failed to execute a successful go-around because the carb heat was left on? I can't imagine it robs *that* much power
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I can tell you this... in the 150hp 172, I've done a t&g and forgotten to turn it off, and it's very noticeable. Push it off and it feels like somebody kicked it in the ass. I could definitely see it making the difference between clearing the trees or not on a short runway. Wouldn't surprise me a bit if it was 10%. If you had a carb temp gauge, I suppose you could observe the temperature rise and calculate it.
 
Jim K said:
I can tell you this... in the 150hp 172, I've done a t&g and forgotten to turn it off, and it's very noticeable. Push it off and it feels like somebody kicked it in the ass. I could definitely see it making the difference between clearing the trees or not on a short runway. Wouldn't surprise me a bit if it was 10%. If you had a carb temp gauge, I suppose you could observe the temperature rise and calculate it.
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This is from another forum where someone asked a similar question but essentially it depends on how much your rpms drop by. If you normally get 2,500 rpms and with carb heat it's only 2,400, you'd lose about 12% (2400/2500 = 96%, .96^3=.88, so 12%).
 
My CFI had a strong preference for taking care of flaps+carb heat after exiting the runway (assuming successful landing). It made sense, less distraction for a student pilot. If you can focus on 1 thing at a time less chance of a screw up.

But then on my final landing for my PPL checkride the DPE wanted to see me "clean up the plane" before we exited the runway. I thought it was a "gotcha!" trap so I told him I'd do that after we taxi'd off.
It wasn't a trap; he continued by saying "I really hope you're not task-saturated with taxi-ing in a straight line down the runway for exit".... I... went ahead and pulled carb heat and flaps.

The post-flight feedback was simply that whatever you do -- you should be consistent about it.
 
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Tantalum said:
Has a plane ever failed to execute a successful go-around because the carb heat was left on? I can't imagine it robs *that* much power
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Several reasons as others have noted. With carb heat off you get all the power available. It also keeps the engine from detonation and this can be more a factor if using auto fuel. I'm flying an experimental and it has a Marvel Schebler ice maker on it so I like carb heat but I turn it off on short final.
 
The first plane I learned to fly that had flaps was a Cherokee, and it was at a short field. I learned to remove all flaps immediately on touchdown, and I think that's best short field technique in that aircraft. Pulling the flaps aids in braking quite a bit. I think it also removes any confusion over next steps when the wheels touch the ground...in that aircraft, that runway. I do the same thing in an Arrow. As others have pointed out, if you confuse flaps and gear in a PA-28, you may not be sober.

Now, in an aircraft with switches that are shaped exactly the same for flaps and gear? Yeah, I could see doing it differently. I'm wondering, though, if those had an ejection seat, would they also use the same kind of switch? (And I'm guessing here...maybe they have a lift/pull thing for gear, as does the Arrow I've flown.)

The aircraft I fly run 100LL or one of the UL variants. My initial training was in a cub, where making ice is secondary only to having fun, so carb heat on at numbers downwind, if not sooner, and carb heat doesn't come off until the airplane is stopped, or the wheels are on the ground and I've asked the passenger to push it in. I know that in theory, the drag isn't going to change much between full idle and stopped engine, but I'm too much of a chicken to see how well I react to the noise reduction. Different aircraft, actual experience in the aircraft engine out? maybe different answer.
 
Why retract the flaps on EVERY landing, because you might need it on a short field? Do you do every take off as a short field take off because you might, one day, have to take off from a short field????

STANDARD procedure should be to leave everything alone until off the runway. It is safer.

If something is DIFFERENT, then you modify your standard procedure for THAT time. So if the field is short, sure, raise the flaps after touchdown for better braking. But in that case, MAKE SURE you are raising the flaps.

Even with a big lever. Think about this, you train yourself to grab that lever and put it to the floor one roll out. Now you get a vintage Mooney. You grab the lever, move it to the floor and retract the gear.
 
I was taught to dump the flaps on rollout and wait till I am clear of the runway to take care of the other stuff.
 
Chrisgoesflying said:
This is from another forum where someone asked a similar question but essentially it depends on how much your rpms drop by. If you normally get 2,500 rpms and with carb heat it's only 2,400, you'd lose about 12% (2400/2500 = 96%, .96^3=.88, so 12%).
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The following are not solutions, only questions.

12% of what? 12% of (RPM ^ 3)?
Ah!, if they aircraft was at a stable speed in level flight and the change was made, then the speed would maybe drop 12% - assuming a proportionate power loss (see below).

At 2,500 RPM the torque curve will be pretty flat (I guess) and so engine power will be proportional to RPM, so a 4% loss. If the torque curve was over its peak at 2,500 RPM, then the power loss would be less.
 
Chrisgoesflying said:
If you normally get 2,500 rpms and with carb heat it's only 2,400, you'd lose about 12% (2400/2500 = 96%, .96^3=.88, so 12%).
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I think this may be misleading, in that one might deduce that losing 12% of one’s power would lead to a 12% loss in climb ability. Maybe not that big a deal.

I think that’s wrong. A plane climbs because of excess power. In a low powered plane, it’s easy to imagine that losing 12% power could result in a 100% loss of ability to climb. Which would be a big deal!
 
This is mostly an argument about technique although there's probably going to be the usual "mine is the one true way" comments.

In the Cessnas, leaving carb heat on doesn't seem to matter much because the location of the control allows it to be pushed in with the same motion as the throttle. Interestingly, despite all the discussions about the differences in carb/engine position, the location of the carb heat control is the reason Piper manuals give for their recommendation to only use as needed.

So, personally, I don't bother with turning off carb heat before landing.

Flaps I don't touch until off the runway. Too many real cases of people accidentally retracting the gear. Just not a particularly good risk/reward equation.
 
Albany Tom said:
Pulling the flaps aids in braking quite a bit
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Exactly. In le Arrow, Dumping flaps and having the yoke in my chest means I don't touch the brakes until just before turning off. And I am carrying very little energy at that point, so the braking is minimal. Since I pay for brake pads, this is my SOP be it short field or 10,000' of asphalt.
Pinecone said:
Why retract the flaps on EVERY landing
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See above. And why NOT retract the flaps on every landing? In my case, because $$$ for brakes.
 
WDD said:
My PPL CFI instilled in me to immediately raise the flaps and turn off carb heat - in that order- after touchdown in case had to take off again.

A recent flight with my CFII ( different instructor) had her comment that I shouldn’t touch anything until clear of runway. Someday might flip up the gear handle vs flaps.

I see merit in both. Thoughts?
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When do you ever have to takeoff?

If you do touch and go operations in a fixed gear airplane, you do have to clean up the plane on the roll.

You should not perform TGs in a retractable gear aircraft. Taxi off and then perform the after landing checklist. A stop and go with after landing checklist is also an option.
 
Much of this topic depends on what you fly and where you fly. If you fly into short strips? Not pushing carb heat in for a go-around can cause serious problems, and last second go-arounds caused by unexpected turbulence aren’t something you practice so not pushing carb heat in is easy to do when your hands are full trying to keep the plane upright and out of the trees. The same is true on bigger airports if a crosswind pushes you off your path. Engine response is far better without carb heat. I consider every landing to be an aborted go-around. My prop is flat and carb heat is off on short final. I do the same at home on a big runway, but I land on either the first or last third of that, depending on wind.
 
On the always lift flaps because of short fields and saving brakes argument...how short are we talking? I used to fly out of an 1800' runway and rolled out normally with limited braking without worrying about retracting flaps.
 
Tantalum said:
How much lift is a wing at 0* angle of attack going 45 knots really generating anyway..?
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Not all of us are at 0* angle of attack on the ground ;).
Stewartb said:
Much of this topic depends on what you fly and where you fly.
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Yeah for sure. I teach primary students to let it be and run through their checklist when off the runway, unless doing a touch and go... But I'm also trying to keep their task saturation as low as possible so they can just focus on the landing.

For teaching STOL you bet your ass flaps are coming up ASAP.
 
My place is 400’ from the east threshold so I try to land and stop in 400’. Coming in the other way I fly over the first 3000’ to land in the last 800’. Lots of Cubs and Cessnas here do the same thing. Twins and jet props like the long pavement. It’s all about what you’re flying.
 
Clip4 said:
You should not perform TGs in a retractable gear aircraft.
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I am not trying to be argumentative here, so please take this only as a question so I can be informed. I have a... uh, friend, who does T/Gs in his retractable gear Piper... may or may not be an Arrow.... :)

Why not do TGs in a retract?
 
Deelee said:
I am not trying to be argumentative here, so please take this only as a question so I can be informed. I have a... uh, friend, who does T/Gs in his retractable gear Piper... may or may not be an Arrow.... :)

Why not do TGs in a retract?
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Arrows have Johnson bar flaps so the chances of getting the flap lever and the gear handle are exceptionally low if you're rushing. In most other retracts they're both switches. So if you're task saturated it's not uncommon to flip the wrong switch at which point your squat switch may or may not save you.
 
Mtns2Skies said:
In most other retracts they're both switches. So if you're task saturated it's not uncommon to flip the wrong switch at which point your squat switch may or may not save you.
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Ah ok that makes sense.... like this?

Yeah the Johnson bar handle is pretty far away from the gear lever in the Arrow.

(that video is so hard to watch)
 
Pinecone said:
Why retract the flaps on EVERY landing, because you might need it on a short field? Do you do every take off as a short field take off because you might, one day, have to take off from a short field????

STANDARD procedure should be to leave everything alone until off the runway. It is safer.

If something is DIFFERENT, then you modify your standard procedure for THAT time. So if the field is short, sure, raise the flaps after touchdown for better braking. But in that case, MAKE SURE you are raising the flaps.

Even with a big lever. Think about this, you train yourself to grab that lever and put it to the floor one roll out. Now you get a vintage Mooney. You grab the lever, move it to the floor and retract the gear.
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Not all planes need flaps for short takeoffs. My RV-8 is airborne in 500’ and climbing through 600 by 3100’ from the start of the takeoff roll.
 
Pinecone said:
Why retract the flaps on EVERY landing, because you might need it on a short field? Do you do every take off as a short field take off because you might, one day, have to take off from a short field????

STANDARD procedure should be to leave everything alone until off the runway. It is safer.

If something is DIFFERENT, then you modify your standard procedure for THAT time. So if the field is short, sure, raise the flaps after touchdown for better braking. But in that case, MAKE SURE you are raising the flaps.

Even with a big lever. Think about this, you train yourself to grab that lever and put it to the floor one roll out. Now you get a vintage Mooney. You grab the lever, move it to the floor and retract the gear.
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I'm not small enough to fold into a vintage Mooney unless I have a double arm amputation above the shoulder. So either way, that won't be an issue.

As I said before, the Comanche skates while the flaps are at 27.
 
Chrisgoesflying said:
I heard in high compression engines like the Cherokee with the 160 HP, leaving the carb heat on at full power during a go-around could damage the engine due to detonations (not sure if that's the correct thing)... I don't know enough about this stuff - I just fly the plane lol, but I don't really want to try it out myself to confirm or debunk ;-)
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In some larger engines that can be a problem, but the "little" Lycomings with their tiny carb heat muffs shouldn't have any trouble. We never did with all the Lyc-powered school airplanes.

In very cold weather, carb heat can help engine acceleration with the carb heat on. It helps the fuel vaporize. That can be critical in the go-around; a stumbling engine can result in a landing you didn't want. One of our Citabrias had exactly that problem during a simulated forced approach to a snowy field; the engine burped and quit when the instructor called the abort, and they ended up stuck in the snow.
 
Ummm. Flaps down, stick full aft, nose high for maximum weight on wheels and maximum air braking.
 
Deelee said:
I am not trying to be argumentative here, so please take this only as a question so I can be informed. I have a... uh, friend, who does T/Gs in his retractable gear Piper... may or may not be an Arrow.... :)

Why not do TGs in a retract?
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Eliminate TGs and eliminate the risk of an early or accidental gear retraction while the aircraft is in ground effect and settling back to the runway.

https://www.faasafety.gov/files/gslac/library/documents/2011/Feb/50765/FLYING LESSONS 110127.pdf
 
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Maxnr said:
Right on. I trained on these and later owned one. Just touch the brakes when the flaps are down and rolling out and you "flat spot" two tires. Its due to a low wing & airfoil that produces excellent lift flaps down, a stabilator (flying tail) that is really powerful when the yoke is forward and a fwd CG. You can, at times see about a foot of daylight under the mains when somebody pins the nosewheel after touchdown and flaps are still full down. This type also has a history of ground loops caused by an FAA term called wheel barrowing. Roll out with mains barely touching, flaps down, the nose wheel planted and a cross wind and she can spin around on the nose wheel. The FAA issued an AC years ago on this W.B. issue. It was canceled years ago but may still be available on the web site. It's a good thing that the flaps are manual and you can go to flaps up with the speed of a switch blade. I was taught from day one not to taxi with the flaps down in any type so that propwash debris doesn't damage the flaps.
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Yep, I put a small flat spot on my right main that way a few months ago. Lesson learned. With the flaps down and the plane rolling at 50mph or so, it really doesn't take much brake pressure to lock up a wheel.

Side note - when I upgraded my radio, we pulled about 12lbs out of the panel between a heavy old radio, an unused CDI, and a bunch of old ghost wiring. Not much as far as useful load is concerned, but being so far forward it made a difference in balance. The plane has been noticeably easier to land since we pulled out all that junk.
 
Deelee said:
Ah ok that makes sense.... like this?

Yeah the Johnson bar handle is pretty far away from the gear lever in the Arrow.

(that video is so hard to watch)
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One would think that having weight on the wheels would lock out gear retraction.
 
Never had any issues retracting flaps to T/O position or pushing carb heat in a go around. I’m a fan of not touching anything on the runway during a full stop landing. There’s literally not one thing leaving your airplane configured that will harm your airplane if you wait until crossing the hold bars
 
Half Fast said:
One would think that having weight on the wheels would lock out gear retraction.
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You would think.

Except sometimes those switches fail. And on some planes, (like Cessna singles) the squat switch is only on the nose gear. So if the strut isn't compressed enough (because you're holding the controls back), you've bypassed that interlock.
 
First off, however you fly your plane is the right way. I'm not trying to get anyone to do anything different than they want to.

But we are trained to manage the airspeed, altitude, attitude, throttle, mixture, prop, trim, tune radios, talk on the radios, write down things we hear on the radios and few other things simultaneously. And if we're IFR, add in flying courses and glideslopes too.

Yet when we're rolling out on the runway while the only tasks are having to keep the plane on the runway and maybe listening to tower tell us which taxiway to exit on and what the ground frequency is, we're incapable of successfully moving the carb heat control and retracting the flaps?
 
donjohnston said:
First off, however you fly your plane is the right way. I'm not trying to get anyone to do anything different than they want to.

But we are trained to manage the airspeed, altitude, attitude, throttle, mixture, prop, trim, tune radios, talk on the radios, write down things we hear on the radios and few other things simultaneously. And if we're IFR, add in flying courses and glideslopes too.

Yet when we're rolling out on the runway while the only tasks are having to keep the plane on the runway and maybe listening to tower tell us which taxiway to exit on and what the ground frequency is, we're incapable of successfully moving the carb heat control and retracting the flaps?
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Descending, slowing down, intercepting the loc are all part of the flying. Is not retracting the flaps until you’re clear of the hold bars going to make you blow through the glide slope?
 
jordane93 said:
There’s literally not one thing leaving your airplane configured that will harm your airplane if you wait until crossing the hold bars
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I disagree. In my Beech, leaving the flaps down will harm my tires during braking, and I have the flat spot to prove it. That’s why there is a required placard on the panel.

This matter depends on the aircraft and the runway.
 
Half Fast said:
I disagree. In my Beech, leaving the flaps down will harm my tires during braking, and I have the flat spot to prove it. That’s why there is a required placard on the panel.

This matter depends on the aircraft and the runway.
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Leaving any flaps down with normal braking will end up with a bald spot on your plane?
 
Half Fast said:
One would think that having weight on the wheels would lock out gear retraction.
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It's always the variables that bite you. An area Bonanza pilot liked to show boat by putting the gear switch in UP and starting the take off roll. Looked cool when the wheels retracted on lift off. He was relying on the Weight on wheels switch to hold the gear down until airborne.
Then he used another runway that remarks said "Pavement in poor condition." The wow switch worked just great up until the first bump. You can guess the rest.
 
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For the folks that apply the brakes on landing, are you based at shorter runways?

I notice when right seat some people seem to coast with minimal or no breaks to the very end while others like to slam on the brakes and make the first taxi
 
jordane93 said:
Leaving any flaps down with normal braking will end up with a bald spot on your plane?
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Leaving flaps full down and applying normal braking can (and often does) skid the tires. The wing is still generating a fair amount of lift with full flaps. It’s a well-known characteristic of the baby Beeches, it’s discussed in the operator’s handbook, and there’s a required placard.

Every plane has its own quirks. Broad generalizations about things like flap use will therefore have exceptions.
 
jordane93 said:
Interesting. Are the flaps the size of a door or is the landing gear/tire assembly that flimsy?
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The Musketeer has average sizes flaps, 6:00X6 tires and MLG struts that use rubber doughnuts. They are robust airplanes according to my CFI. He was a Beech test pilot. He was on a different project. However, he told me of riding with a Musketeer test pilot who wrung it out. Wing tips were seen deflecting two feet.
See my #23 post and that should cover it.
 
RussR said:
I'm trying to think of the case in a light airplane where, once landed, and apparently rolling for at least a little bit, it would make sense to take off again instead of just stop.

The number of realistic scenarios for that must be really small.
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Yeah like once in a fiction novel the first cfi wrote but couldn’t get published because it was the dumbest story ever told.
 
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