So, I was watching a video today from valdez of the guy with the green straight tail 172 like mine. I am totally fascinated with guys performance this year and last year. What I noticed is from the moment he releases the brakes, it looks like he is "pumping" the yoke back and forth. You can see the elevator flapping up and down. What is that all about? What's th benefit? Obviously whatever he is doing works since me made a 90' takeoff with an O-300 powered 172! I'd love to talk to this guy if any of you know him. I've mananged to get mine off in under 300' with just me and 3/4 tanks.

Here's the video:

https://instagram.com/p/BUDU64bFO8f/

Dynamic control input?

Well if you just crank it back you're adding drag. He's probably just finessing it to hold the nose off but not to much. I don't just crank back on the Mooney because it definitely adds a lot of extra drag. I usually wait till around 40kts to start really pulling it off. So maybe this is what he's doing...finessing!

It's up, then there's full power it's down then level then up again just at rotation. Watch it again. That's also a 172 striped down to bare bones with a 15mph headwind at sea level. Also great pilotage

Akt

aktahoe1 wrote:It's up, then there's full power it's down then level then up again just at rotation. Watch it again. That's also a 172 striped down to bare bones with a 15mph headwind at sea level. Also great pilotage

Akt

I've watched the video probably 20 times and there's a lot more than up down up going on there. I totally get that it is stripped down and a nice headwind but thats still amazing. If you've ever flown anything powered by an O-300, you understand.

aktahoe1 wrote:It's up, then there's full power it's down then level then up again just at rotation. Watch it again. That's also a 172 striped down to bare bones with a 15mph headwind at sea level. Also great pilotage

Akt

Watch it a couple of more times - I count 4.5 diminishing up/down cycles from brakes released until the final yank off the ground.

I think he's sampling elevator effectiveness because he knows how it feels when he can yank that sucker up. I'd be curious to hear what he would describe the motion as. For all we can guess out here, it might have been as simple as shifting his hand for a better grip on the yoke.

Can't seem to post it. I don't think it's anything more than what you just said.

It's up and down then brakes released and its level then full yoke back and up he goes.

I guess one could imagine he's pumping the elevator to create a tail fan creating more forward thrust but that's a huge stretch.

Someone post it

Akt

So... using the elevator as a flipper, to help create thrust? I know that not's what you mean, but let's start the rumor that it's a good technique It will be comical to use next time I'm in a STOL contest. Seriously, though I didn't see the video, I'd bet he was just getting a feel via the elevator effectiveness to how soon he could lift off. Too much of that may cost him a little drag though.

You wanna see some impressive Valdez action, watch the video of Frank Knapp in his Lil Cub. Wow!

https://youtu.be/B-T9bFPr8k0

That is great flying. Interesting that it looks like he starts with 10 degrees of flap and then uses full flaps to pull it off. Im guessing that has 40 degrees and the Johnson bar?

daedaluscan wrote:That is great flying. Interesting that it looks like he starts with 10 degrees of flap and then uses full flaps to pull it off. Im guessing that has 40 degrees and the Johnson bar?

The straight tail 172s have manual flaps just like your 170. Popping full flaps at just the right time really will reduce your ground roll, and this is a great example of that. You'll see just about everyone in the STOL competition do this.

I'm curious what his empty weight was, how much fuel, and pilot weight. Also curious what prop and pitch, that can make a big difference as well. He has a STOL kit also, not sure which one. Great flying for sure! Watching someone do this in a 172 is more impressive than a purpose built light weight expiremental doing it even shorter IMHO.

A buddy of mine has an 0-300 172 with a climb prop. Up here where we live at 6500ft, it takes about 12-1400ft to get that hunk off the ground solo, no rear seat, low fuel, etc. Impressive well setup plane, but regardless of mods and whatever has been done, it's amazing to see one of those get off the ground that short!

That's pretty astounding.

I'm sure that the propeller used is a competition-only prop, and that there was about five minutes of fuel on board. Wouldn't surprise me if there are NFS pistons somewhere inside that cowling, and perhaps a bit more than the tiny zap of juice that comes from a standard magneto.

And I will guess that if the FAA happened to do a CG balance ramp check on the airplane at that contest, it would not meet the TCDS. Removing the battery (and starter, and generator) and hand-propping it would take 50+ pounds out and move the CG back at the same time.

Did anyone have a readout of the headwind at that particular moment? Looks like it may have been a little more than 15 MPH?

No matter how well he race-prepped the airplane, it is a spectacular performance.

I think he is using the prop blast, relative wind, and dynamic control movement to get the nose wheel light before he releases the brake.

EZflap wrote:

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And I will guess that if the FAA happened to do a CG balance ramp check on the airplane at that contest, it would not meet the TCDS. Removing the battery (and starter, and generator) and hand-propping it would take 50+ pounds out and move the CG back at the same time.

So would doing something like that in a normally certified aircraft be .... hmmm... . at the moment the right word fails me.... completely Kosher? Does Valdez operate on some sort of an "Honor System"? Just curious.

For experimental I suppose it's all okay... just about anything goes. Regardless, that was an amazing performance of plane and pilot. Hat's off.

I also know there is some wiggle room for special " Exhibition-Air Racing Certification and Operations "
Link: http://www.faa-aircraft-certification.c ... acing.html

I would guess that any FAA inspector who would be at Valdez AK on the STOL competition day would more than likely leave his/her FAA "hat" back in the office on that day.

Actually it wouldn't surprise me that the "honor system" is being used, but not in the way you may be thinking. I'm guessing that they might all tacitly understand and agree its a competition, and that when the competition is over the certified airplanes are put back in certified condition.

EZFlap wrote:I would guess that any FAA inspector who would be at Valdez AK on the STOL competition day would more than likely leave his/her FAA "hat" back in the office on that day.

Actually it wouldn't surprise me that the "honor system" is being used, but not in the way you may be thinking. I'm guessing that they might all tacitly understand and agree its a competition, and that when the competition is over the certified airplanes are put back in certified condition.

Totally irrelevant to the original post. I don't care about the legalities of the contest or the FAA. I'm truly interested in learning more about his technique.

My guess is something along the lines of trying to get it light on the nosewheel also.

Using the spring gear to his advantage maybe? Rock it up and down to lessen wheel weight drag?

I've now watched the video half a dozen times, and while I can see the elevator action, I don't see that it does much to benefit the short take off, Popping the flaps is where the airplane leaves the ground, and of course, it takes practice to know what the airspeed needs to be before doing that to achieve the departure the way he does. Definitely outstanding use of what little the airplane has to offer.

Cary

Jeredp wrote:
Totally irrelevant to the original post. I don't care about the legalities of the contest or the FAA.

Well actually, I may have been posting a reply that was relevant to Denali's comments, as opposed to the original post. Hope that's not too burdensome.

As for pumping the yoke directly, one other reason I can think of might be that he is trying to get the nosewheel oleo strut fully extended. If you take the weight off the nose, the strut will extend and usually stay there, leaving the airplane in a slightly nose high angle for the takeoff run, slightly reducing the amount of up elevator that is required to rotate for takeoff.