Lg a/c terminology;Greg?

Let'sgoflying!

Let'sgoflying!

Touchdown! Greaser!
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Dave Taylor
What does 'heavy turn' mean? Seems to reference a lg a/c moving from hold short to the rwy.
 
"747s heading to all the way to Hawaii lining up on the numbers WITHOUT a "heavy turn" but we have RJ drivers on the way to KBHM doing "heavy turns" to line up on the piano keys"
 
I suspect it may have to do with turning the other way when entering the runway to go to the very end and then turn around so you can use every inch for takeoff. The term "heavy turn" is probably related to the fact that they usually do this only when they're really heavy, i.e., right up to max gross. I routinely do such "heavy turns" in my not-very-heavy Tiger because I'm a big believer in the Three Most Useless Things in Flying, one of which is "Runway behind you." Sounds like someone's griping about those RJ's spending more time on the runway for takeoff than the poster feels is necessary, and thus delaying the poster's departure. If I were the pilot of the RJ, I'd tell the poster to pound sand -- I'll use all the runway I can get, thank you, because I never know when I really might need every inch.
 
" The only problem I have with the 'heavy turn' on to the runway is that it is usually followed by a flex thrust or derated takeoff. "
 
My guess would be a combination of what Ron mentioned and also the practice overshooting the center line with the nose wheel then making a really sharp turn to line up. Long planes (usually heavies) have to do it to get the back wheels over the centerline without having to pull way down the runway. I don't think it's an official term, either way. Sounds like you were talking to a controller recently?
 
Let'sgoflying! said:
" The only problem I have with the 'heavy turn' on to the runway is that it is usually followed by a flex thrust or derated takeoff. "
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That sort of defeats the purpose of the "heavy turn," and I think that's the issue here. If you need all the runway, you should also need all the thrust. If you hog the runway just so you don't have to go full thrust, you're making others pay for your issues.
 
Ron Levy said:
That sort of defeats the purpose of the "heavy turn," and I think that's the issue here. If you need all the runway, you should also need all the thrust. If you hog the runway just so you don't have to go full thrust, you're making others pay for your issues.
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Reduced or Flex thrust is determined by several factors but one of them is not doing a "heavy turn" on the runway. Essentially if you meet the criteria you can reduce the takeoff thrust and not compromise runway performance. Reduced takeoffs reduce wear on the engines.

It's all a matter of technique. When flying jets I prefer to make a rolling takeoff coming out of the taxiway if possible. The performance charts are based upon a static takeoff so if you are already rolling you have gained some kinetic energy.
 
Rotor&Wing said:
Reduced or Flex thrust is determined by several factors but one of them is not doing a "heavy turn" on the runway. Essentially if you meet the criteria you can reduce the takeoff thrust and not compromise runway performance. Reduced takeoffs reduce wear on the engines.

It's all a matter of technique. When flying jets I prefer to make a rolling takeoff coming out of the taxiway if possible. The performance charts are based upon a static takeoff so if you are already rolling you have gained some kinetic energy.
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Thats a great point and why I always felt that a rolling TO on a short field made more sense than position and hold to full throttle to double check instruments. I always thought more speed earlier mean airborne sooner and the chance of clipping a tree was greater than and engine failure on TO. No support for this just my gut.
 
AdamZ said:
Thats a great point and why I always felt that a rolling TO on a short field made more sense than position and hold to full throttle to double check instruments. I always thought more speed earlier mean airborne sooner and the chance of clipping a tree was greater than and engine failure on TO. No support for this just my gut.
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Just think kinetic energy. The heavier the plane the more effect this has.
 
Spool-up time is also a factor. If you have a really high-inertia engine (like the old centrifugal flow engine we had in the TF-9J Cougar, which was 13 seconds idle to mil), you may well do better to stop and spool than to take it on the roll, unless you can get a lot of speed on the roll onto the runway or can max the throttles long before you're lined up. With the piston engines most of us use, spool-up is nearly instantaneous.
 
AdamZ said:
I always thought more speed earlier mean airborne sooner and the chance of clipping a tree was greater than and engine failure on TO.
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Yes, unless the acceleration is slower during engine power-up, and you end up with less speed later.
 
AdamZ said:
Thats a great point and why I always felt that a rolling TO on a short field made more sense than position and hold to full throttle to double check instruments. I always thought more speed earlier mean airborne sooner and the chance of clipping a tree was greater than and engine failure on TO. No support for this just my gut.
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You may not have any supporting documentation for this but I assure you it is SOP for any bush pilot worth more than his weight in moose turds :yes: :cool2:

On the other hand letting it get away from you - especially in a tail-dragger - will not result in a short takeoff run but rather a ground loop or a plane in the trees before the halfway point :sosp: Which is probably why they prefer student pilots to concern themselves with the static runup and release method of short-field takeoffs.
 
Rotor&Wing said:
It's all a matter of technique. When flying jets I prefer to make a rolling takeoff coming out of the taxiway if possible. The performance charts are based upon a static takeoff so if you are already rolling you have gained some kinetic energy.
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Depending on weight and type of nosewheel steering (and level of experience :tongue:), I have found this tricky. If you pour the coals to it while you're still coming around the turn, I have found you can be pointing towards the weeds accelerating very fast. :yikes: To avoid scaring my captain and myself I'll keep rolling slowly until lined up with the centerline before moving the throttles forward.
 
Lance F said:
Depending on weight and type of nosewheel steering (and level of experience :tongue:), I have found this tricky. If you pour the coals to it while you're still coming around the turn, I have found you can be pointing towards the weeds accelerating very fast. :yikes: To avoid scaring my captain and myself I'll keep rolling slowly until lined up with the centerline before moving the throttles forward.
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LOL Lance. The Lear has much quicker acceleration, engine and otherwise, than a "heavy". Besides, I don't think anyone was suggesting you set takeoff thrust while still in the turn. :)

I had to get used to the Sovereign. There is a noticeable delay between advancing the throttles and the resulting thrust, but when you get it, you get it allatonce!
 
Rotor&Wing said:
Not sure I understand what you're saying.
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Imagine you're flying a TF-9J, which takes 13 seconds to go from idle to mil. You roll onto the runway and without stopping, advance the throttle to mil. In the 13 seconds it takes to spool up, you've rolled a long way down the runway at a very low acceleration rate, so you're well down the runway at little mroe than taxi speed before you get full thrust. OTOH, if you pull up, stop, run it up, and don't release the brakes until you see 100% RPM, you get your head pushed back in the head rest pretty good as that full thrust accelerates you a whole lot faster, and you use less runway reaching rotation and liftoff speeds. If you try to push the throttle up earlier (like leaving the hold short line), you maybe get that ride Lance F described or even what happened to Dick Martin on that tricycle on Rowan & Martin Laugh-In.
 
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Ron Levy said:
Imagine you're flying a TF-9J, which takes 13 seconds to go from idle to mil.
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Ok, I thought we were talking in terms of modern aircraft.

My technique if the jet is rolling down the taxiway is to stand up the throttles as we come through the turn onto the runway. As we are lining up set TO thrust. At that point you've built up considerable energy and speed. Even coming from a full stop on the taxiway with break away thrust you can still do this. No problem with nose wheel steering (unless ice or very wet) just release the tiller after centerline lineup. The only thing to watch for is if a small aircraft is behind you then you have to be careful.

The Performance data is determined from a rolling start from stop and not from a stop/max thrust/break release.
 
Ron Levy said:
Some more modern aircraft have high spool-up times, too, especially those with high-inertia high-bypass fans.
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Not as long as the old engines. Plus you are talking spool up from flight idle whereas if you are already above flight idle the spool up time is considerably less.

On any aircraft of considerable weight (which is what we are talking about here to begin with) just to move the aircraft from a complete stop will take what is called "breakaway thrust" and that alone will reduce spool up time.
 
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