The art/science of flying a Cub

Along the same vein, flying a cub that is....

I exercised some poor ADM last Sunday and got away with it, not proud of it, I just want to learn from it. I found out what severe turbulence is to me in a Supercub. If someone out there has an insight into flying in severe turbulence and appropriate technique for handling the same I would love to hear it. I know how I handled it (not fun) and had I had any idea what I was letting myself in for I would have stayed on the ground and caught the smoker home. My story is below and I offer it in the hopes of saving someone else from the discomfort and hazard I put myself in.

My Super Cub and I were on my way home from Fairbanks through, dare I say it, "Windy Pass".

As you can imagine with a name like that the wind has been known to blow there, last Sunday was no exception. The McKinley Park weather advisory was reporting surface winds in the 20mph range with occasional moderate turbulence. Not being a complete idiot I thought to myself, self lets go over the foothills of the range headed southbound at 7500 feet or so and stay out of most of this nonsense. Well as I approached Healy I was experiencing up and downdrafts in excess of 1500 fpm with some expected wave action off the ridges. At one point as I was nearing 10,000 feet and experiencing a headwind of approximately 60mph according to the GPS I did the math and realized at 46 mph across the ground that i didn't have enough fuel to play this game trying to slog it out up top and I was going to have to descend due to ceilings on the south side of the pass anyway. Now McKinley Park airstrip, for those of you that haven't been here is about 7 or 8 air miles from Healy up the pass and was only reporting 20 with gusts to 26 on the surface. So I did the math turned a little west towards the pass and descended to 3500 as I passed McKinley Park. It was a little bumpy but not too bad and I was making 74mph across the ground, so far so good. As I neared the south end of the pass the turbulence caught me I was approximately 1,000 feet agl and the next thing i know I am being tossed around (literally and figuratively). My head hit the overhead 4 times should harness wasn't tight enough, the sleeping bag that was tucked into the extended baggage knocked the removable back off my back seat and everything in the rear seat pouch hit the ceiling and then the floor. For the next eternity (about 10 minutes or so I "flew" through the pass alternately standing on one wing or the other, finally settling into a 20 degree or so nose down attitude with about 2300 rpm to maintain altitude (yes nose down) if I tried to get closer to level I gained altitude and got tossed even harder. From then on it was a throttle and rudder game until I got spit out the other end.

Long story I know, but can someone give me a rule of thumb about wave height of turbulence in proportion to wind speed? Is there such a thing? This is one of those I don't want to go there again things, but at the same time we sometimes find ourselves unexpectedly in situations and have to work through them. The best solution would have been not being there and I now know that, but when you are there how do you determine the altitude that will give you the best ride? Thanks in advance for what I am certain will be an enlightening series of posts.

http://skyvector.com/?ll=63.58521575906958,-148.93676521429666&chart=39&zoom=1

Hi Dale.

That is a bad area when its windy. I hit it in the Boeing all the time. When it blows like that the waves continue higher than us. Usually 37,000 or higher. We will see turbulence from the McKinley area past McGrath and usually get out of it by Unalakleet. The same in every direction depending on the wind. There are days where you wonder what you got yourself into. nasty.

I had a similar experience a number of years ago in Rainy Pass. That turbulence was so bad that I was almost knocked out when my head hit the x brace. It convinced me to get a helmet. I've worn one on every flight since.

dalec, That is a tough area. You did not mention anything about the winds aloft direction and velocity. Flying on the downwind side of McKinley with high winds aloft will generate turbulence all the way up above the oxygen levels in a Cub. I realize that it is a long way around but in the circumstances which you describe it likely would have been smoother heading over to the McGrath side of the big mountain. It is smoother on the up slope side of a hill. Ground speed would be higher with a lower power requirement and it could be glassy smooth. Perhaps, without me knowing the weather, going the long way around through Rainy pass would have been a better choice on that particular day?

Going West wasn't an option there was a front out west ceilings were to low, while I could have gotten to McGrath I probably would have been forced to fly all the way to Lake Clark and around.

Winds aloft at Talkeetna were reported as 3000' 25 knots @ 210, 6000' 60knots @ 180 degrees. Interestingly enough when I came out the south end of Windy I picked up a 25 mph tail wind. Needless to say the winds were all messed up.

Now back to my original question: Has anyone ever seen or heard of a rule of thumb that correlates wind velocity with wave height of turbulent air? What I am trying to get at is, would I have been better off at 200' agl than 1,000' agl? I was already in the midst of it and wonder if there is something that I could have done to reduce the impact of the turbulence. Believe me when I say, had I known how rough it was going to be down there I wouldn't have gone.

I dunno (no experience w/that yet) but have been told that if you get caught in the wind in a valley, it's worse near the tops, bumpy below, but usually a more steady wind (one way or the other) down low in the valley. Seems that moving around to find the "best" place to fly would be prudent. Since winds, terrain, A/C weight, etc, will always be different there is probably no "rule" to follow, but like many things, try this 'n that to see what works best.

Flame retardant suit on, whad'ya's think about that?!

I find that some pipe insulation on the upper tubing helps, not with the turbulence but with the size of the bumps on your head. ;-)

Glenn

NimpoCub said:

have been told that if you get caught in the wind in a valley, it's worse near the tops, bumpy below, but usually a more steady wind (one way or the other) down low in the valley

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This seems (to me) to be an important bit of info to know about. MUST BE some opinions, or better yet, some experience w/this idea. I know that things are different all the time, but is this a generally good theory??

Thanx (I hope)

In the one valley (Matanuska) that I have enough experience to comment upon, what I've found is that the air is indeed bumpier up high, while the wind blows steady down low. What I consider a pretty good blow is with wind from the East: when the normal 10 minute flight from Palmer to the cabin takes 20 minutes or more. In that situation, what I've found is:

- Up high (it's all relative, but that means 3500 - 4000 for me), the air is rough, bumpy but "do-able"
- Lower (circa 1500), the wind is steady, with infrequent rolling bumps.....however, this may not matter since I have a strip in the valley and......
- If one is trying to land into that steady wind, the terrain effect (is that the right word for the wind blowing over the hills and ridges?) makes it far bumpier than it was up high and causes donut pinching in the seat.

With the newly updated -12, a strong wind from the East translates to a great day not to go to the cabin.

I don't profess to be any better than the rest, I am just throwing in my two cents. I agree with what is being said, practice maneuvers and landings. My preference is to practice all that stuff at or near MCA up at altitude. Rarely have I ever been scared at altitude in cruise configuration, so I try to practice at MCA. I do most of my sweating when the ground is approaching too quickly or not departing quickly enough which oddly enough happens at low airspeed.

Cubs don't have a lot of aeileron authority, and it isn't the appropriate control at slow speeds anyway. Flying hours in cruise configuration, I find myself incorrectly trying to use the stick to correct a dipping wing when at low speeds. Last thing you need to do when approaching the ground at slow speed is stall an already stalling wing.

If a wing starts to dip on short final, the most likely cause is the dipping wing is stalling. Of course throwing the stick over only increases the angle of attack on the already failing wing; the tool of choice is the rudder. When I am out and about on a day with a little turbulence, I slow down to MCA or my usual approach speed, trim the elevator, center the stick and hold it there. Corrections are then made with the rudder. Practice with the rudder until it becomes instinct.

The other item that helps me is to practice crosswind landings every chance I get. I am blessed with a river that has lots of large, open gravel bars and a predominant wind down the river. I see lots of pilots out practicing landings with the wind on the nose. I like to start with a small crosswind component and land with increasingly more crosswind as I feel comfortable.

I, like all the rest here, only make those picture perfect landings when there is absolutely no one around to see them. I received a compliment from a flight service person once when I walked in for a weather briefing. I had landed at the airport for fuel in a nasty crosswind. I made the landing described above: one wing low, rode it out, and made my turn onto the exit and nose into the wind just as the other wing settled. After adding fuel, I went in for the briefing. When I asked for the briefing and told her I was flying a Cub, the FSS attendant replied, "Unless you can fly like that guy that landed the Cub about 10 minutes ago, don't even try."

I think it pays to practice rudder contrl and crosswind landings for someday I may have to do one for real.

Sorry, but I have no idea about flying cubs, (200+ hours all together is my total flying time ) and I´m just asking since there is a curved ball on your message that I am trying catch....

What do you mean by MCA? are you on a MEA... or maintaining a MOCA? How is that different from getting up to safe clearance off the ground? IFR talk is new to me so I´m trying to learn something new here. Pls don´t shoot the messenger, I live in VFR world, and don´t go to VMC areas just because...

Hi JM,

He was refering to: MCA "Minimum Controllable Airspeed"

(he was hanging the airplane on the edge of a stall and keeping the wings level with the rudder.)

In IFR flying MCA is minimum crossing altitude and is used to plan a climb to an airway with a higher MEA.
In our cubs we just look outside and if an obstacle is too close we pull back on the stick and push the throttle forward a bit. Saves on having to do all that fancy math!

Thanks, like I said just learning here. Better grasp of the comment now.

JM - just like this...

njneer said:

JM - just like this...

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Steady! Cool stuff, thanks for sharing. Wish you could capture the AOA on that picture! How high are your from QFE?

AOA = A lot like being in a reclining chair. I don't have an artificial horizon, so I don't have a number on the AOA. When I first added vortex generators, I experimented with slow landings. I can touch the tail wheel with the mains about 2 feet above the pavement. Did that once, it is really tough on the equipment.

QFE (?) = field elevation? I was out over Knik Arm (near Anchorage, Alaska) approaching Birchwood airport at 2,000 feet MSL. Field elevation is 96 feet.

When I first added vortex generators, I experimented with slow landings. I can touch the tail wheel with the mains about 2 feet above the pavement. Did that once, it is really tough on the equipment.

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If you want another challenge try dragging the tail wheel without letting the mains touchdown. After I installed the VG's this summer I was up doing slow flight above the Knik arm and my Spidertracks unit recorded me at 26 mph. I love slow flight, it really helped me get my head wrapped around short field work in my cub. It made a huge difference in the places I was willing to take my cub.