Turning into the wind for runup

Tantalum said:
How many people are flying their single engine piston with a sustained wind speed of 30 knots?
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Tantalum said:
I highly doubt the more typical 3 to 5 knot that most people see does anyting...


At least.. but compared to a 45-minute preflight the 15 minutes for the run-up is not bad


...I do notice that in gusty winds I get funky RPM readings, but that's true also facing into the wind I have found as the relative wind speed for the propeller changes by the same factor
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If most people only fly in 3-5 knots, why do we bother teaching X wind take off and landing, proper aileron position during taxi and ground reference maneuvers? Yes, most the time there is no need to turn into the wind, but it is equally important to know when you should.
 
I'll only point into the wind if I'm behind a student (or a plane that looks like a flightschool plane on a single lane taxiway). My runup takes <2min but I'm not going to sit with a warm engine facing away from the wind if someone is learning how to check for mag drops. Interestingly I often have to wait before I can run up for the oil temp to rise to 50 deg (Rattletex 914) - and this wait can continue after arriving at the runup bay if there hasn't been a strongish tailwind during the taxi.... Oil temps idling on the ground after runup facing into the wind are around 78. Out of the wind I've seen 90. My $0.02
 
Mike Blackburn said:
Interestingly I often have to wait before I can run up for the oil temp to rise to 50 deg (Rattletex 914) - and this wait can continue after arriving at the runup bay if there hasn't been a strongish tailwind during the taxi.... Oil temps idling on the ground after runup facing into the wind are around 78. Out of the wind I've seen 90. My $0.02
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That’s my challenge in the Waco. Takes FOREVER to get the oil up to temp. If it’s cool out, I basically point away from the wind while waiting for the oil to warm up and then point into the wind for the actual run up.
 
Fearless Tower said:
Usually just the people getting paid.
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Yep.

I always assumed we did runups into the wind to avoid dinging up the prop. Never thought about engine cooling, but seriously how long does it take to check the mags and cycle the prop a few times? It should be about a 30 second affair.
 
Ryan F. said:
I'd much rather see consideration given to where the tail is pointed
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:yeahthat: I'm amazed how many pilots have no conception of where there prop blast is going or what it might do. Don't instructors teach that any more?

I do agree that on a high wind, gusty day, you may want to turn some airplanes into the wind, particularly tail wheel airplanes. That's a different operational consideration. Engine cooling is a non-factor in "most" conceivable scenarios.
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I've been flying almost exclusively taildraggers for the last 40 years. If there's enough to affect my choice of where to point my nose when doing a runup, it's probably too windy to fly anyway.

My runup consists of checking the mags and carb heat, takes about 15 seconds. I'm usually more concerned with the engine being sufficiently warmed up, not overheating.
 
Lindberg said:
How do y'all do rolling runups without riding the brakes?
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I fly on grass and when it is high and wet, I have to taxi my 150 at at least 1500 rpm just to get moving sometimes. So easy enough on a wide grass runway to mag check at 1700 while going from the center to one end for takeoff.
 
Damn you fellas are arguing about something that would be so easy to test in any airplane with CHT and a breeze. Are we taking bets? I bet OWT.
 
I have flown with many dirt field dirt runway bush pilots in the Sierra Madre of Mexico and the mag testing is done while taxiing and using partial brakes. The idea is to keep the prop moving in front of the gravel being pulled up. As said it's best to look for planes on final but if there is going to be a long ground running then do this into the wind and then turn toward the runway approach then wait and scan for traffic.

And when starting the take off run, if there is enough runway, open the throttle slowly to get the plane moving ahead of the gravel and then full throttle. Since my runway is dirt I do the above all the time.
 
kgruber said:
It is not recommended. Turn in the direction that you can see base leg and final, without blasting anything behind you.
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Actually page 2-17 of the Airplane Flying Handbook recommends,

“Air-cooled engines generally are tightly cowled and equipped with baffles that direct the flow of air to the engine in sufficient volumes for cooling while in flight; however, on the ground, much less air is forced through the cowling and around the baffling. Prolonged ground operations may cause cylinder overheating long before there is an indication of rising oil temperature. To minimize overheating during engine run-up, it is recommended that the airplane be headed as nearly as possible into the wind and, if equipped, engine instruments that indicate cylinder head temperatures should be monitored. Cowl flaps, if available, should be set according to the AFM/POH.”

There is no recommendation to position the aircraft to see base leg and final for the pre take off check. Also the best way to assure the plane in front isn’t going to blast you is to maintain a safe distance.
 
DavidWhite said:
Yep.

I always assumed we did runups into the wind to avoid dinging up the prop. Never thought about engine cooling, but seriously how long does it take to check the mags and cycle the prop a few times? It should be about a 30 second affair.
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Don't thing the folks on floats take very long. They do it as they taxi..
 
I point in the direction the run up is best designed for. Usually, that is either 90 degrees, or into the prevailing wind.
 
AKBill said:
Don't thing the folks on floats take very long. They do it as they taxi..
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On floats you typically taxi downwind to maximize available take-off distance into the wind and typically taxi at idle to avoid water damage to the prop, so there's really no good time to do a full mag check on the water unless you are step taxiing. (I would often do quick one at idle just to detect a completely dead mag.)

The good news is that an engine problem on take-off is usually not a big problem with plenty of lake ahead of you, and you can always check them at normal power as you approach to land.
 
If wind makes that much difference, then what do you do when wind is calm?
Clip4 said:
Actually page 2-17 of the Airplane Flying Handbook recommends,

“Air-cooled engines generally are tightly cowled and equipped with baffles that direct the flow of air to the engine in sufficient volumes for cooling while in flight; however, on the ground, much less air is forced through the cowling and around the baffling. Prolonged ground operations may cause cylinder overheating long before there is an indication of rising oil temperature. To minimize overheating during engine run-up, it is recommended that the airplane be headed as nearly as possible into the wind and, if equipped, engine instruments that indicate cylinder head temperatures should be monitored. Cowl flaps, if available, should be set according to the AFM/POH.”

There is no recommendation to position the aircraft to see base leg and final for the pre take off check. Also the best way to assure the plane in front isn’t going to blast you is to maintain a safe distance.
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If pointing into the wind is necessary for cooling, what does one do when there is no wind?
 
dbahn said:
On floats you typically taxi downwind to maximize available take-off distance into the wind and typically taxi at idle to avoid water damage to the prop, so there's really no good time to do a full mag check on the water unless you are step taxiing. (I would often do quick one at idle just to detect a completely dead mag.)

The good news is that an engine problem on take-off is usually not a big problem with plenty of lake ahead of you, and you can always check them at normal power as you approach to land.
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I stand corrected, thanks
 
Do you really mean this? Wouldn't it be better do this before pulling on to the runway since a plane maybe just about to touch down where you have taxied? I do agree with the 360 since with light wind airplanes might land or take off either direction.
 
dtuuri said:
Y'mean a 270 don't ya? Or maybe a 450, depending which way? I prefer the former. :)
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I carry an inspection mirror in the Cub (NORDO) and will sometimes check behind me and if no one is behind me do a 360 turn on the taxiway just to view all of the airspace around the intersecting runways. It's not so important on single runways but it still helps to rotate enough to see where a landing airplane will be turning from downwind to base. I can't say that I've ever thought to do that on the runway, however. Now, come to think of it I've never seen anyone else do that either.
 
The primary reason I favor turning into te wind for a run up is so my rpm checks are normal and consistent. Sit 90* to the wind and your rpms vary. Why bother doing mag and prop checks if you can’t believe the tach?
 
dbahn said:
I can't say that I've ever thought to do that on the runway, however. Now, come to think of it I've never seen anyone else do that either.
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It used to come in handy here back in the day. That taxiway at the approach end of runway 3 (used to be runway 2 before the north pole moved left) isn't much wider than the wingspan of a Piper Colt. You could clear final, but not base. So, across the runway you go after checking final and around the button to clear base and downwind. If somebody was on base you'd have time to head back off the runway. We all did power off approaches in the Colt, so a base leg was tight to the runway, hidden behind tall trees and difficult to see anyway from a Colt.

2G1.jpg​
 
Now think about doing a runup in a twin while the ramp is covered with ice....

It is done usually while taxying.
 
My recollection from reading Deakin is that a direct tailwind was actually just as good if not slightly better than a direct headwind in terms of cooling.

But, it's merely one of many things to take into consideration when deciding where to point during a runup. Wind direction, OAT, presence of other airplanes or something else that may get blasted behind me, etc...

write-stuff said:
If you can find that study, I'd really like to see it. When doing ground runs with the cowling off, temps go up really fast. With the cowling on (and prop blast therefore being circulated over the engine), temps stay manageable. I infer from this that the prop is responsible for most of the cooling.
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Fearless Tower said:
That is because the cowling keeps the airflow around the engine. You will see a difference between cowling on or off regardless of where the wind is.
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write-stuff said:
Yeah, I believe that's what I said.
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@write-stuff, I took your post to mean exactly what you said: That "the prop is responsible for most of the cooling". But it's the cowling that's responsible for the cooling (by directing the airflow around the engine properly), not the prop.
 
Lindberg said:
How do y'all do rolling runups without riding the brakes?
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Quickly.

You can check mags and exercise the prop without gaining too much speed, particularly if you're on a long straight taxiway. But not if you're reading it off of a checklist and squinting at the tacho trying to distinguish between a 50 and 55 RPM drop.
 
flyingcheesehead said:
My recollection from reading Deakin is that a direct tailwind was actually just as good if not slightly better than a direct headwind in terms of cooling.
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I like Deakin, but in this case (and how many others, I wonder?) he's offering opinion, not fact.
 
Weekend Warrior said:
I read a study once that said the prop produces almost 0, nil, nothing, in regards to cooling air at run-up. And, the best cooling is obtained by pointing either directly at the wind, or directly away.
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Ryan never said why....he just invoked Deakin. lol

According to the wise folks at APS....it has to do with "reverse" flow out the cowling around the prop hub....and some measured theory using video and tufts.

They claim that a "tail wind" is better for improved engine airflow than facing into the wind. The prop acts like a disk and the flow is directed off the disk into the engine....Could be....but I doubt it makes that much of a difference....cept when arguing over the topic on an internet forum. :D
 
Zeldman said:
Now think about doing a runup in a twin while the ramp is covered with ice....

It is done usually while taxying.
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We had a guy take a 135 checkride in the King Air when it was pretty icy out...I think they did the run up on the runway so they had room to slide.

When they got back, the Fed said, “Nobody’s reported it, but it’s nil out there.”

I said, “No, it’s not...it’s poor.”

Him: “It’s very poor.”

Me:”But it’s still poor.”

Him: “When’s your next checkride?”

Me: “Next week, but it’s scheduled with somebody else.”
 
PaulS said:
To cool the engine. Don't know about you guys, but my engine is idling most of the time until take off. Also the airflow from the propeller is minimal near the crankshaft.
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Yes. Look at the prop. It is narrower at the base near the spinner. The prop is not designed to blow air into the cowl, it is designed to blow air over the control surfaces. In flight you do get the full force of the moving air into the cowl.
 
JOhnH said:
Yes. Look at the prop. It is narrower at the base near the spinner. The prop is not designed to blow air into the cowl, it is designed to blow air over the control surfaces. In flight you do get the full force of the moving air into the cowl.
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Yes, but you also get an augmentor effect because of the fast moving airstream that is passing the air exit.
 
Lindberg said:
How do y'all do rolling runups without riding the brakes?
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Depends on the size of the ramp/taxiway, which way the wind is blowing, whether or not there's a Pilot Rated Passenger in the right seat, whether there's dual controls/brakes, etc.
 
Stewartb said:
The primary reason I favor turning into te wind for a run up is so my rpm checks are normal and consistent. Sit 90* to the wind and your rpms vary. Why bother doing mag and prop checks if you can’t believe the tach?
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If the winds aren’t gusting does it matter? And if the winds are gusting does it matter? I’ve never seen rpm jumping about regardless during run up that would interfere with leaning for altitude and other checks.

I guess what I’m saying is that let’s say you get a 10 kt gust. Will that cause an rpm differential greater than say 25-50? I don’t know. I’ve never seen the rpm fluctuate during run up...ever. And yes, I’ve performed the run up perpendicular to the winds quite often.
 
I thought we were talking about winds? If it didn’t make a difference I wouldn’t have said it.
 
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