The International Cessna^® 170 Association

Do flap gap seals make deference?

AR Dave wrote: The 2nd fastest and easiest way to take-off from a short field.
Line up straight and set flaps to 20.
Pick up the tail to 2”.
Let it fly off almost on its own. (slight Pull)
Clean to 10 and accelerate
Clean to 0

I use a slightly modified approach.
Line up straight and set flaps to 10. (easy to reach handle / less drag)
Just before it starts to fly I pull flap handle to 20. It now feels like you are on an elevator.
Clean to 10 and accelerate
Clean to 0

The less parasitic drag the better, I would think. I have flap gap seals and even aileron seals (although I'm not sure what the aileron seals are). My mechanic was talking about them during my annual last week. I've always had flap gap seals so I don't know, before vs after.

N2865C wrote: I use a slightly modified approach.
Line up straight and set flaps to 10. (easy to reach handle / less drag)
Just before it starts to fly I pull flap handle to 20. It now feels like you are on an elevator.
Clean to 10 and accelerate
Clean to 0

Only been flying my 170 for a month, but so far this is the approach I've been using to get off the ground / climb quickly as well.

Any part of the story below that is a violation of any FAR didn’t really happen. The rest is true, mostly.

Hoping to once again commit aviation, I put the whip to my ragwing C170. The 80/43 prop wound up, and 02V accelerated downwind and downhill. Galloping along, I could feel the jolts from the tussock-covered tundra through the tubular frame of the 50-year-old pilot’s seat, the 180 gear, and the 8.50X6.00 mains. What in retrospect seems like a ridiculously small Scott tailwheel brought up the rear of this accident looking for a place to happen. The flaps were set at zero degrees.

With the yoke in my left hand, I began to feel anxiously for the point where the gathering speed would cause the empennage to fly. I wanted desperately for the tailwheel to stop crashing from tussock to tussock, and an early lowering of the nose on takeoff reduces drag by fairing the wings with the relative wind.

The caribou hunter standing ahead and to the right of my takeoff roll marked the point at which this bucket of bolts was either going to fly or I was going to have to pull the throttle and stand on the binders. No one wanted to see 02V in a crumpled mess at the bottom of the ravine, which marked the end of this short section of relatively smooth tundra.

The beauty of Alaska on this crisp fall day was almost enough to bring tears to your eyes. But, at the moment, I had other things on my mind: If this takeoff didn’t work out, I might soon have something very ugly to cry about.

Don't ask me how I got talked into retrieving a couple of caribou hunters and the fruits of their labor from the side of a mountain near Sparrevohn. My former instrument flight instructor had dropped two of his buddies off here about 4 or 5 days earlier. However, on departure, he found the rough tundra a bit challenging for his nose-wheel-sporting C172. When he got back to town, he came to me, suggesting my plane would be more suitable for picking up his camouflage-clad chums, their gear, and their bags of meat. Naively, I said it sounded like fun, and that was that.

We left Merrill field early in the morning, rolling down the runway as a flight of two. Nearly two hours later, the C172 was left at Sparrevohn, a military radar installation with a 4100 foot, one-way, gravel airstrip. My former flight instructor accompanied me in my C170 on the 10 minute hop to the “hunting strip,” which derived its designation from the fact that someone had hauled out and left about four or five traffic cones.

Following an uneventful arrival, Iloaded up some meat, some gear, and one of the hunters. I tried to takeoff uphill, into the wind. But, before I could gain flying speed the plane was into tussocks as tall as the wheels, and the takeoff was aborted. It took all four of us to maneuver 02V back to the area of less severe grass clumps. We decided that a downhill, downwind takeoff should be attempted. I asked my former instructor if he would like to handle the honors. He declined but said he would accompany me with a load of meat and we would see what happened. We positioned the plane, reconfigured the load, stationed the above-mentioned hunter at the point of reckoning, and climbed in.

I thought I heard “fly you bastard, fly” being mumbled from the right seat as we bounced down the mountainside. The ravine loomed ever closer, but the tailwheel, except for the bouncing, wouldn’t yet come off the ground. The plane was gradually feeling lighter, but the tussocks, like three-foot waves during a rough-water takeoff, were sapping most of the plane’s ability to accelerate. The tail bounced high, and I yanked on full flaps. But, the plane still would not fly, so I dumped them just as quickly. The tail settled back to the tundra. The hunter to the side of our path came and went. My former instructor yelled, “We’re committed now.”

Once again, I pulled on all the flaps in a single, quick motion. Miraculously, the plane jumped off the tundra, stall horn wailing, just moments before plunging over the edge of the ravine.

Although we had not planned it, we had just executed a “carrier takeoff.” When the ground goes away, ground effect goes with it. The nose was lowered instinctually, and I promptly bled off the flaps as we gathered speed. The ravine was wide enough that the flaps were up and we had enough speed to raise the nose and initiate a climb by the time we reached the far side. Also, the downhill side of the ravine was lower than the uphill, so we easily cleared that obstacle as we climbed away. I turned to my buddy and said, “I don’t think I can do that four or five more times today.” The man in the right seat wasn't up for more of the same either, and he said so.

After retrieving the C172 in Sparrevohn, we dropped the hunters a note wrapped around a rock. It said we would send the cavalry. On our way back to “Anchor Town,” we stopped at Lake Clark for fuel. At the lodge, we left directions and instructions for one of the commercial operators to ferry the boys out in a tundra-tire-equipped Super Cub as soon as they could fit it into their busy hunting-season schedule.

The day was waning as we walked back to our freshly-fueled planes. I noticed the weather towards Lake Clark Pass wasn’t looking very good. I asked my buddy if we had time to get through the pass before dark. “If we leave right now,” he said over his shoulder as he climbed into his plane. I followed him on the back taxi and into the air. It was raining long before we got to the pass. Night had fallen by the time we entered it.

I followed his strobe as his plane threaded its way through the notoriously treacherous geography. Through the dark and the rain, I could just make out the white of the glaciers spilling down the black mountains on both sides of us.

Breaking out into the wide open of the west shore of Cook Inlet, we were still a long way from home. But the gas flares on the tops of the oilrigs out in the inlet sure were a welcome sight.

Gordon Sandy
N4002V

Great story, I like it.

I believe a quote from Arnold Schwartzenegger was in order. You ever see "Commando"? He's in a Grumman Goose talking off from the water with a hapless female student pilot ( the movie's damsel in distress) at the controls. "Fly or die!" he bellows, then as the airplane takes off :"works every time!"

Eric

That used to be my motto when I was flying RC planes in my teens........... there's nothing left of those birds but some old busted motors, and trashed servos. Ahhh, "fly or die" those were the days.

Gordon, ... You gonna just GIVE that kind of writing talent away??
Nice job. If so, how 'bout writing another version for the 170 News? All our members would surely enjoy it.

Just to give consideration to a few things:
Anything which creates additional drag will generally lengthen a takeoff.
This includes flaps extended prior to actual flight, elevator not streamlined (as in trying to prematurely lift the tail) prior to flying speed, etc.
By starting out with the tail feathers faired (i.e., with the elevator in nuetral position) and with the flaps retracted, and then accelerating to flying speed and "popping" the flaps to a takeoff setting, (while using prior experience to also provide exactly the right amount of up elevator simultaneously with the flap deployment) ... then in theory at least... the shortest takeoff roll will be achieved. The airplane accelerated without the drag penalty of deployed flaps....until the exact moment of flight when the takeoff flaps were suddently "set" by "popping" them... And the airplane also didn't suffer the additional induced drag of a downward elevator placed in such a position by a pilot anxious to get the tail up prematurely. (In other words, if the airplane began the takeoff roll with the elevator faired nuetral...then the tail came up as it was ready to come up of it's own accord...which happens to be a signal to the pilot that the airplane is approaching flying speed anyway.)
If a pilot then simply appies a small back-pressure (actually a relaxing of backpressure since the elevator no longer needs to be held nuetral) to prevent the tail from further rising....then the airplane will not waste additional forward motion building unnecessary additional speed prior to lift-off.
The problem then exists in simply determining that exact moment when...with flaps deployed...the airplane will leave the ground. That's the moment the flaps would need to be "popped".
Practice, practice, practice.
Of course, that's a lot of "technique" and practice. And such experimentation is rarely if ever accurately documented. Most of us are not likely to be that exact or that proficient. Not even Cessna's test pilots were good enough or proficient enough to warrant promoting such techniques. They were certainly loathe to document any such techniques sufficiently to endorse them. And they had the benefit of experience, perfect, light-weight airplanes, and accurate documentation.
For the majority of us, it's probably best to do just what the book recommends. Set the flaps prior to takeoff. Release the brakes after power is set. Allow the tail to rise of it's own accord to a tail-low takeoff position... and let the airplane do what it was documented to do.
Just read the documentation so you'll know what it's gonna do before-hand.
I recall (when I was much younger, renting someone else's airplane) going into the shortest strips I could find, just for the thrill of getting back out of there. (The old Almeda-Genoa airport's southwest-bound runway comes to mind, as well as the old southbound grass strip at the old in-town Bay City, neither of which still exist.) I'm pretty certain that tree leaves left chlorophyll on the lower wing surfaces on some of those takeoffs that gave me such pleasure.
Now that I'm older, fatter, and own the airplane I fly,... I'm a lot less willing to give myself such challenges.
I suspect the undocumented performance of tundra grass and down-hill slope in the bush country remains conjecture to the rest of us. These airplanes, operated in such conditions, become the unique tool of the experienced bush-pilot in such situations. There's a reason they're successful at what they do. The rest of the wannabes either have their epithets on gravestones... or enjoy the tales of those bushpilots that do it regularly, ...while snug and safe by our fireplaces.