Flaps on touch and go

[201er]

2 minutes ago, kpaul said:

just saying its a complex aircraft is a copout.

No. It's that if you forget something doing touch and goes in a skyhawk, nothing will happen. If you forget something in a Mooney, you may be sitting on your belly (gear up), roasting your engine (cowl flaps), or stalling (trim or forgetting to set prop forward).

[kpaul]

Just now, 201er said:

No. It's that if you forget something doing touch and goes in a skyhawk, nothing will happen. If you forget something in a Mooney, you may be sitting on your belly (gear up), roasting your engine (cowl flaps), or stalling (trim or forgetting to set prop forward).

Yep, same things can happen on an instrument approach, or a even a day VFR arrival.

I'm not judging, if the PIC is not comfortable doing a T&G that is fine, that is why they are the PIC.

[201er]

Just now, kpaul said:

Yep, same things can happen on an instrument approach, or a even a day VFR arrival.

I'm not judging, if the PIC is not comfortable doing a T&G that is fine, that is why they are the PIC.

I agree. But if we, as humans, have a screw up rate of 1 in a 100 or 1 in a 1000 or whatever it is, by intentionally doing touch and goes in a complex airplane, you're increasing the likelihood that one of your human factor screw ups will happen during the "go" rather than being caught on the ground prior to the next takeoff. You've never once forgotten to push the blue knob forward or forgotten to retract flaps?

[kpaul]

Just now, 201er said:

I agree. But if we, as humans, have a screw up rate of 1 in a 100 or 1 in a 1000 or whatever it is, by intentionally doing touch and goes in a complex airplane, you're increasing the likelihood that one of your human factor screw ups will happen during the "go" rather than being caught on the ground prior to the next takeoff. You've never once forgotten to push the blue knob forward or forgotten to retract flaps?

Honestly, NO.  Besides the blue knob is already pushed up prior to landing.  I use the same procedure in large and small planes and have for years, that is the advantage of military flight training, they do a good job of beating checklists and procedures into your head.

I also go-around if not down within 200-500' feet of my intended point of touch down, if the trim or flaps took me too long to set/retract on a T&G I will abort the T/O. 

Sure everyone can have a bad day and forget something and sure I could avoid all mistakes by leaving the plane in the hangar.  But that is not why I started flying 30 years ago and not why I own a airplane. 

[Hank]

40 minutes ago, 201er said:

I agree. But if we, as humans, have a screw up rate of 1 in a 100 or 1 in a 1000 or whatever it is, by intentionally doing touch and goes in a complex airplane, you're increasing the likelihood that one of your human factor screw ups will happen during the "go" rather than being caught on the ground prior to the next takeoff. You've never once forgotten to push the blue knob forward or forgotten to retract flaps?

I grew up on (several) Marine Corps air bases, and watched many complex, multi engine jets perform touch n goes (and heard many more!). They have much more to do than do we in our Mooneys.

The first time I took my mother flying, jumpers were in the air when we returned to the field, and the nearby Delta invited me to come do a touch n go while waiting for the meat missiles to clear. So we did. Mom commented that after seeing and hearing so many touch n goes, it was nice to finally do one.  

[jaylw314]

7 hours ago, M20Doc said:

Shouldn't they have been opened prior to landing in anticipation of a possible go around a long with prop forward, mixture rich (as needed based on field elevation) etc?

Clarence

My go around mental checklist has cowl flaps open AFTER cleaning up the plane.  Things have slown down and the cylinders don't heat up THAT much in 10-15 seconds.  "Flaps & flaps" is easy to say and remember, and the controls are right next to each other.

Edit:  Ooops.  Looks like a bunch of people already commented on this

Edited June 24, 2017 by jaylw314

[David Medders]

On 6/24/2017 at 5:40 AM, M20Doc said:

Shouldn't they have been opened prior to landing in anticipation of a possible go around a long with prop forward, mixture rich (as needed based on field elevation) etc?

Clarence

Taking the risk of introducing actual data into the discussion: No, cowl flaps should not be opened prior to landing. The most significant cooling in my JPI data occurs just prior to touchdown and during roll-out. Opening cowl flaps prior to landing will exceed my maximum recommended temperature change, A.K.A shock-cooling. My cowl flaps stay closed until clearing the runway.

Given a runway of sufficient length, a touch-and-go is not the risky or dangerous operation described by some in this thread. We must always be prepared for a go-around or balked landing.

Cheers

[jetdriven]

I never heard of opening cowl flaps prior to landing before this forum. I leave them closed until after landing.  I've also forgotten to open them on a go-around and it's nbd.  You have about 3 minutes before the CHT even gets close to 360. So, for a VFR go-around it's still ok.  Not optimal but better than dumping cool air into the engine at an even greater rate with the power almost completely off.

Edited June 25, 2017 by jetdriven

[Guest]

5 hours ago, David Medders said:

Taking the risk of introducing actual data into the discussion: No, cowl flaps should not be opened prior to landing. The most significant cooling in my JPI data occurs just prior to touchdown and during roll-out. Opening cowl flaps prior to landing will exceed my maximum recommended temperature change, A.K.A shock-cooling. My cowl flaps stay closed until clearing the runway.

Given a runway of sufficient length, a touch-and-go is not the risky or dangerous operation described by some in this thread. We must always be prepared for a go-around or balked landing.

Cheers

The great thing about this is that we are all free to operate our aircraft and engines as we see fit.  I open my cowl flaps on short final at the same time I push the prop control forward with one last look at the gear lights.  

I'm ready for the over shoot if required.

ive never noticed a change in CHT as a result of opening them on final, nor has it set the alarm on my JPI.

Clarence

[jaylw314]

37 minutes ago, M20Doc said:

The great thing about this is that we are all free to operate our aircraft and engines as we see fit.  I open my cowl flaps on short final at the same time I push the prop control forward with one last look at the gear lights.  

I'm ready for the over shoot if required.

ive never noticed a change in CHT as a result of opening them on final, nor has it set the alarm on my JPI.

Clarence

You should be fine.  IIRC, shock-cooling is a worry if you are starting at high power and high CHT.  On final, you've already been at low power and low CHT for a few minutes, so any further cooling is not an issue.

I think the reason most checklists do not call for opening cowl flaps on final is to reduce workload during short final.  You shouldn't open them at your GUMPS check, because you might very well be at high power and high CHT right before that, otherwise it would make sense to include it as a prep for the go-around.  That's a good enough reason for me to wait until after the go-around.

[David Medders]

18 minutes ago, jaylw314 said:

You should be fine.  IIRC, shock-cooling is a worry if you are starting at high power and high CHT.  On final, you've already been at low power and low CHT for a few minutes, so any further cooling is not an issue.

jaylw314 -- I am fascinated that you completely ignore actual JPI data. Being naturally aspirated, perhaps your Mooney is more forgiving. However, your statement is demonstrably inaccurate for a portion of the Mooney fleet.

David

[David Medders]

1 hour ago, M20Doc said:

ive never noticed a change in CHT as a result of opening them on final, nor has it set the alarm on my JPI.

Clarence

I can see how cowl flaps would not have much impact with your cylinders hanging out in the breeze.

 

[carusoam]

Reference to the M18... Not the Big8...

-a-

[jaylw314]

38 minutes ago, David Medders said:

jaylw314 -- I am fascinated that you completely ignore actual JPI data. Being naturally aspirated, perhaps your Mooney is more forgiving. However, your statement is demonstrably inaccurate for a portion of the Mooney fleet.

David

I'm paraphrasing some of Mike Busch's webinar's through EAA.  Can't remember which ones, but he commented on that a few times.  There's also this article

[carusoam]

Lots of discussions that are airframe specific...

There is always a similar, but separate discussion on cooling the Turbo after a flight...

My C's cowl flaps were variable, but got set like the newer ones...

I haven't found the cowl flaps on my O yet... 

Back to flaps...

1) Some set T/O flaps for landing and use them for T/O....  minimum requirement for setting cowl flap changes and trim changes...

2) Some don't use T/O flaps...

3) Some land full flaps and reset for T/O flaps, adjust the trim, while verbal mediating a short memorized version of the T/O checklist...

4) I taxi back, reset everything, then execute the T/O checklist old style... and I'm OK with that... 

I'm not as big of a fan of approaching the end of the runway at flying speed and not having all my ducks lined up.  Having the trim set way up can be pretty disconcerting after rotation.

Best regards,

-a-

 

Edited June 25, 2017 by carusoam

[David Medders]

19 minutes ago, jaylw314 said:

I'm paraphrasing some of Mike Busch's webinar's through EAA.  Can't remember which ones, but he commented on that a few times.  There's also this article

I am confused.

Your initial position was, "...shock-cooling is a worry if you are starting at high power and high CHT."

Now your position is shock cooling is not a problem at all?

I will stick with Lycoming's recommendation.

 

[Guest]

3 hours ago, David Medders said:

I can see how cowl flaps would not have much impact with your cylinders hanging out in the breeze.

 

There are actually eight of them all huddled together in my cowl.

Clarence

[jaylw314]

3 hours ago, David Medders said:

I am confused.

Your initial position was, "...shock-cooling is a worry if you are starting at high power and high CHT."

Now your position is shock cooling is not a problem at all?

I will stick with Lycoming's recommendation.

 

I'm confused, too.  Welcome to the club.

I'm not sure where you think I said "shock cooling is not a problem at all."  My read on the article was that it might not be as large a problem as we think it is, but that we need more information that we don't have.

I tested it out this afternoon.  On short final, my CHT's were already between 310-320.  After opening the cowl flaps, they came down to 270-290 on landing.  Fastest cooling rate was -43 degF/min.  With the cowl flaps closed, they came down to 285-295, with the fastest cooling rate -36 degF/min.  Both are within Lycoming's -60 degF/min suggested max cooling rate.  granted, it was a hot day out (95 degF), but unless your CHT's are in the 400's right when I pop open the cowl flaps and reduce power, I just can't see it being faster than -60 degF/min.

[johncuyle]

Interesting, My 75F are infinitely adjustable.

I've got a 1980 K. Mine are infinitely adjustable. I have flown a J model with three position (up, takeoff, full) and I strongly prefer the latter, especially for go around and touch and gos. I don't do touch and goes much because getting it trimmed back to takeoff takes forever and it requires a LOT of forward pressure on the yoke to not stall when power on, 10 degrees of flaps, and full up trim. Anyone know if it is possible to switch the infinitely adjustable over to the three position setup?


Sent from my iPhone using Tapatalk

[gsxrpilot]

I'll say it. shock cooling is not a problem at all in fact it's just one of those Old Wives Tales that seem to hang around forever. A lot of it probably has to do with Lycoming's lawyers not letting them change their documentation for liability reasons. It has nothing to do with what's in the documents, but any change invites liability.

I think you'd find that most owner pilots that are very involved, studied, and keeping up with information and research, have let this myth die long ago.

 

[Guest]

RAM Aircraft of Texas suggests that Shock Heating can be just as much trouble.

http://www.ramaircraft.com/Maintenance-Tips/Engine-Shock-Heating-During-Takeoff.htm

Clarence

[Hank]

9 minutes ago, M20Doc said:

RAM Aircraft of Texas suggests that Shock Heating can be just as much trouble.

http://www.ramaircraft.com/Maintenance-Tips/Engine-Shock-Heating-During-Takeoff.htm

Clarence

Sounds like a turbo problem. He recommends standing on the brakes and advancing the throttle to 27-30", waiting several seconds, then applying takeoff power. Do think I've ever seen 30" MP in my Mooney . . . So I'm safe.

P.S.--ever seen the in-cockpit videos of Bob Hoover? No, I don't move my throttle between WOT and Idle/Cutoff nearly as fast, but I'm also not nearly as slow as some here suggest for takeoff. Couple of seconds, I'm done.

[ArtVandelay]

RAM Aircraft of Texas suggests that Shock Heating can be just as much trouble.
http://www.ramaircraft.com/Maintenance-Tips/Engine-Shock-Heating-During-Takeoff.htm
Clarence

Takeoff is one thing, but pulling back the throttle is another.
I would argue that the 2700 RPMs (or more, since tachometer may not be accurate) have more to do with takeoff failures than the internal heating of the engine. My ears tell me there is a huge difference between 2700 vs 2600 RPMs, I now back off the prop on takeoff a turn to 2650, engine seems happier.

[midlifeflyer]

...and another topic was referred to as a "food fight!"

Two of them in this one. Simple technique choices reaching religious proportions. 

[PTK]

I think shock cooling has to do with the rate of coolng and the starting temperature of the cylinders. It's more of an issue if the starting cht is high and the rate of cooling ( °/min ) is high. Lycoming recommends to not exceed 50° F /min. If the cht's are not allowed to get too high then the impact of cooling rate is not as high. If cht's are allowed to get high then the rate of cooling has a bigger impact.

A cylinder starting at say 450°F and cooled to say 340° at > 50°/min is shocked cooled. If that cylinder starts at 400°F and is cooled to 340° the rate has a much lower impact because the temp delta is much lower. If that makes sense.