daedaluscan wrote:I am unconvinced by the video. Maybe someone could remake the video it with a slighty more accurate approach?

Personally I feel that no flaps, tail up, yank on the Johnson bar, release to 10degrees and accelerate in ground effect gets me off the ground the fastest/shortest but I would be the first to admit that it is just that - a feeling. Besides it just feels like fun:)

Here ya go.
https://youtu.be/

What's left out is tire size. Larger tired increase AOA. The Skywagon has manual flaps for a reason. Though that technique worked for him, blend number 1&4 for 29's or 31's and you will smoke number 1.

Akt

RKTX wrote:

daedaluscan wrote:I am unconvinced by the video. Maybe someone could remake the video it with a slighty more accurate approach?

Personally I feel that no flaps, tail up, yank on the Johnson bar, release to 10degrees and accelerate in ground effect gets me off the ground the fastest/shortest but I would be the first to admit that it is just that - a feeling. Besides it just feels like fun:)

Here ya go.
https://youtu.be/

Bravo! Well done.

Other than to win a short takeoff ground run contest, the real advantage of a short ground run, of using flaps or elevator or both to make the aircraft fly as soon as it will in low ground effect, is to maximize seconds of acceleration in low ground effect. More seconds of acceleration in low ground effect is airspeed in the bank at our time of greatest need going just over the obstacles with assurance about the outcome of the takeoff.

Leaving low ground effect earlier and clearing obstacles by more altitude than necessary is like giving up our takeoff go around. We may not need the extra free energy. There will come to day, however, when we will wish we had not given it up so quickly.

I don't usually do a me-too, but this time I vote twice: First for AKT and the tire size making a difference.
Second vote is for Contact and staying in ground effect as long as feasible. Which is not as easy as it reads.

Wannabe,

Stay dynamic and proactive on the elevator. Wiggle the control wheel for and aft . Put the nose just a little low, high, low, etc. We do that in the crop field all the time, to stay ahead of the aircraft.

Contact

Agreed on the better AOA afforded by bigger tires and extended gear.

I drew a very different conclusion watching his video. While he in fact appeared to have an increased ground roll using techniques that have helped others shorten their ground roll, I cloud not come up with the conclusion that the others were wrong. The conclusion that was more obvious to me was that he simply hadn't mastered the other techniques.

I have personally watched too many people slam their tail in to the ground while trying to do a flap jump. Slow motion video of this happening in a supercub is exceptionally telling, as on many cubs the fabric between the ribs will ballon when loaded. When such a plane has the tail hit the ground on take off roll you can actually watch the balloons deflate (in other words the wing unload) only to have to start the process all over again, consequently lengthening the ground roll. It doesn't mean the technique doesn't work, it just means they fubar'd it.

RKTX's video was a good example of how performed correctly, his (RKTX's) technique will shorten the roll, watched in slo mo you can see he just kisses the ground with the t/w. Which to me says that even though he's already debunked the AOPA video, he might even be able to get it shorter

In the AOPA video he doesn't appear to hit the ground with the tail, but watching the inside footage over a few times, it appears he never quite gets the airplane 'on the step' and consequently has very little rotating to do. He appears to be essentially just willy nilly yanking flaps from a very low attitude followed by a weak rotation... In his case simpler is probably better, but as RKTX has shown, he's leaving performance on the table.

Having said all that, there is a lot of 'how they do it in Valdez' that just doesn't work for every application. Load your plane with a month worth of camping gear, and then try and lay the whip to it on a gravel bar from a standstill... Might be fine in a cub with 6" gear and 35's, but probably a piss poor idea in a 180 with a wood cored prop

Take care, Rob