Some folks I see applying pretty large pulses of power when dragging it in for a short landing. I have always used pretty smooth application of power and still land pretty short. I have not played with the technique, but is there anything to gain from cycling from idle to Burst when holding off from touch down way behind the power curve? I would think that smaller inputs on a well planned and stabilized approach would be best. It seems like it might be hard on the engine and prop as well.

If I need more power I push the throttle, less I pull it. Kinda like looking at the ASI and VSI while landing. I don't, and I don't worry about what they're doing. Eyeballs and seat of pants work fine. If it's windy, and hot with lots of sink the engine gets used as another tool to land me where I want. Cold and smooth not much gets changed.

I don't think running throttle in/out are hard on the engine and prop. You're not exceeding any limits.

Gump

I agree with Gump. In a strong downdraft, I go full throttle and then adjust. In a strong updraft, I close the throttle and then adjust. Unlike the quick control response of rudder and elevator, throttle and aileron give slow control response.

When we baby the throttle, we never bracket the proper glide angle. In the downdraft, we add throttle too slowly. In response to going shallow on the glide angle, we slowly add too much throttle and go high on the glide angle. The result is landing long. In the updraft, we reduce the throttle too slowly and go high on the glide angle. When we start down again, we add throttle too slowly and go low. Low scares us so we slowly add throttle and go high. The result is landing long.

Because nature is dynamic, our control movement (including throttle) must be dynamic. Unlike rudder control, however, throttle control must be reactive and dynamic. Rudder controls the longitudinal axis only by being proactive and dynamic. The throttle changes glide angle too slowly to comfortably bracket glide angle proactively. If we get right on it and don't baby it, the throttle will do fine controlling the glide angle reactively.

In reference to the hover taxi, or dragging it in, yes the throttle and elevator must be used dynamically and reactively to prevent touchdown until arrival at the desired touchdown spot. The advantage of the hover taxi, or dragging it in, is that extreme low ground effect allows controlled flight at very low speed. Going well below stall speed in low ground effect on an approach to landing is sometimes very, very advantageous.

Delete, posted in the wrong thread.

steve wrote:The width of my farm strip used to be about 1/4 the size of yours and it was plenty wide. It is hard to tell from a picture if there is any change in elevation down the length of your strip, if there is (and depending on your soil types) I would suggest installing a perforated drainage tile about 60 cm under the surface, the entire length of the strip (just off to the side of where you would normally land), providing there is a place to outlet the water. If if you have anyone that installs drainage tile in your area this would be much more desirable than using gravel, as it would dry the ground quickly and no prop concerns as with using the gravel. I you are handy, have access to a backhoe and laser, or transit, you could do it yourself. I used to have a drainage business, feel free to ask if you have any questions.

Steve

I'm guessing this was meant for motoadve drainage question eh Steve?
David

Revving the engine must be hard on it.
You are accelerating lots of parts and increasing the stresses on the engine overall. Stress = wear and tear. No different to cycling the prop during run up, you want to minimise it to minimise engine stresses.
You are also creating thermal cycles, albeit very small localised ones, but they stress the metal also.

The larger the engine, the larger the rotational inertia, and the larger the forces required to accelerate it. More force means more wear and tear. Obviously this kind of wear pales in comparison to the wear and tear which happens at start up. But the point is, smaller engines are faster to react or will wear less with this kind of "throttle jockeying".

I am like you, I typically use a pretty smooth action, but of course you go for the throttle quick when conditions require it... On a gusty day, I end up working the engine more than I would in steady winds.
I think some guys have a genuine feel for the throttle and get added control from jockeying it, but I think some others end up 'over-controlling' the aircraft.

You're not going to hurt anything in an aircraft engine with occasional bursts of full throttle operation, or conversely, suddenly pulling it back to idle. It's been my experience that the harder you run 'em, the better they do and the longer they last. I think the stats show overwhelmingly that engines that have been babied have way more problems throughout their lives, and are way less likely to reach the recommended TBO.

And, like Contact says, for short field operation, your engine/prop is another control to use to get you to the specific spot you want touch. If you don't use it you might as well be flying a glider. Just chop the throttle at downwind and coast every time. Doesn't work real well, and THAT is hard on engines.

Gump

Using that throttle is the only way to nail your intended spot every-time. I'm talking within a couple inches or a foot or two, otherwise like Gump says, it's a glider and your either short or long on your precise spot. Elements play a huge part as well. Gotta use that throttle.

Akt

Pitch = airspeed
Power = altitude

Quick power adjustments matter for accuracy landings (tires, floats, skis). Many pilots struggle with the concept.

Ever flown with Greg Miller? He's not afraid of the short burst, like blipping the throttle on a dirtbike. It's amazing how just a half second of 1200 rpm can make a difference. It's usually in the final moments before touchdown though to make the spot, whereas sustained power is more appropriate above 50 feet for the glide slope.

GumpAir wrote:You're not going to hurt anything in an aircraft engine with occasional bursts of full throttle operation, or conversely, suddenly pulling it back to idle. It's been my experience that the harder you run 'em, the better they do and the longer they last. I think the stats show overwhelmingly that engines that have been babied have way more problems throughout their lives, and are way less likely to reach the recommended TBO.

And, like Contact says, for short field operation, your engine/prop is another control to use to get you to the specific spot you want touch. If you don't use it you might as well be flying a glider. Just chop the throttle at downwind and coast every time. Doesn't work real well, and THAT is hard on engines.

Gump

I agree you need to run the engine hard regularly for it to last. Running an engine hard is different to jockeying the throttle.

You can run an engine up to red-line on a test bed and keep it there for weeks on end, and it will go long past TBO. It's a common test, they don't mind that one bit.

The fact is, cyclic stress is what damage mechanical things. It's a big part of my job, so when you talk about gunning the engine that's the first thing I think of. Wear and tear. Like I say, it's not the biggest cause of wear and tear, but it's certainly not helpful! I agree that an "occasional blast" is nothing to think twice about.

I agree that you need to use the throttle to hit your spot. My point is, going crazy with it 24/7 isn't helpful for the engine. I'm not saying you're going to miss TBO, I'm saying fly thoughtful of the engine - it's the most expensive bit, and as you point out it keeps you from becoming a glider...

This is especially true with a larger engine. Smaller ones have a greater tolerance for "play-time".

I know I am alllllll over the throttle when I'm working on short field ops. I think I picked that up from something Greg Miller said in one of his videos

Zzz wrote:Ever flown with Greg Miller? He's not afraid of the short burst, like blipping the throttle on a dirtbike. It's amazing how just a half second of 1200 rpm can make a difference. It's usually in the final moments before touchdown though to make the spot, whereas sustained power is more appropriate above 50 feet for the glide slope.

Greg is one guy who can really pull every last bit of performance out of his plane, and I think the first time I saw some footage from Valdez he won the landing contest using pretty dramatic bursts of power as he dragged it in for touch down.

I understand the pitch and power relationships well, just have never utilized the burst technique. I am not scared to drag it in super low and slow to minimize energy at touch down, but I am usually only making very small changes to the throttle. I will start experimenting with the burst method and see if I notice any benefits.

Combine throttle with ground effect and it's amazing how much you can slow down before touching the ground.

Gump

As you "burst" the throttle you also suddenly increase rudder and elevator authority with the increased airflow over the tail and must compensate by relaxing the initial control inputs. Aggressively retarding the throttle you decrease the same airflow and must now respond with increased inputs as you are now close to the ground. The fact that you now enter ground effect and are operating below the power curve also complicate the manoeuver.
It seems that a lot of students and new backcountry pilots need a few hours to coordinate the inputs.
My observations anyway...

The time it takes a young student to learn is heavily dependent on the teaching method. The attitude that I can do this only because I have lots of skill and experience, the right stuff, is not conducive to rapid learning. The more casual attitude that this is not rocket science, this is just a simple machine, etc. is more conducive to rapid learning. Students learn by doing. All my primary students soloed quickly using techniques that other instructors said were for advanced students only. If we concentrate on aircraft control and taking the student from where he is to where he wishes to be, full control competency I assume, that can happen quickly.

Isn't mastering these "complicated manoeuvers" the point of all this backcountry flying stuff?

Gump

GumpAir wrote:Combine throttle with ground effect and it's amazing how much you can slow down before touching the ground.

Gump

Agreed Gump. Coordinated with wings level and power on, you can push most well designed slow flying planes incredibly far before they will do anything weird. If you pull the power out of this dance, things can change pretty quickly. That's why I am wondering what the theory is behind unsteady power application when going for the low airspeed, ground effect, high-precision touchdown.

Slow and steady seems to suit me well, but some really good pilots that I know use other methods.

I can't speak for anyone else, but my use of sudden throttle for short field work is all about seat of the pants feeling and arresting sink. You can feel the plane enter ground effect, and depending on descent rate, it often takes a healthy burst of power to arrest your sink. Then it's just a matter of keeping the airplane off the ground with throttle and elevator until you want it to touch the ground. And, in what attitude you want it to touch the ground. Increase pitch to get your speed down. Throttle, often lots or all, to make the airplane go up and down.

It's like watching the proverbial Cherokee 140 take off from Truckee on a hot summer day with four pax and full fuel. They pitch it in the air with elevator, and have just enough power to make it fly in ground effect. And down the runway they go, wallowing around until they get scared and pull power, or run it off the end of the runway into the trees.

Same thing, only you work that with throttle, whatever throttle it needs, to make the airplane go precisely where you want it to. It's way easier in real life than it sounds, and like Contact says, "it ain't rocket science." It's just another tool in the bag of tricks that comes with practice. Go find some long stretch of dirt to play on, and practice staying in ground effect with the gas pedal. It changes from the Cherokee wallow to hovering a few inches off the dirt with all the control in your throttle hand like magic.

And yes, you might have to jockey the throttle, so beware!

Gump