I read all the aopa comments. Sounds like a bunch of pavement pounders. I wonder what they would say about being soloed out of a 1300 ft grass airstrip before hitting 20 hours in a c170b. Much less taking the plane in there at 100 deg full fuel and guys?

I'm not sure the Aopa bunch would approve of this article, I know as they pointed out I'm not a Cessna test pilot, but I have learned some things that are contrary to what the POH says. Please forgive me in advance, I like Aopa. I love backcountrypilot.

Please read and file in the back of your mind.
FAA versus reality

Richard
http://www.avweb.com/news/pelican/18208 ... directed=1

The article is exactly what we were trying to explain to those idiots. They have no clue, no experience, and will certainly attack anyone questioning their limited, strictly by the book, POH wisdom.

Guess it's no different than a group of rock crawlers with Jeeps, or motocross guys trying to explain themselves to a bunch of guys who tour the roads, and think anything that might get their chrome dirty is absolutely nuts. Not the group to go to for technical advice on how to work a rock face, or expect them to understand the how and why of what you're doing. They have no frame of reference and think you're crazy, and back up their position by reading the warning page of the Jeep's owner's manual.

Gump

Richard,

I agree with him that the FAA ways for short field takeoff, both with and without the 50' obstacle, are wrong. It would have been much better, all these years, if they had just used the soft field method for all takeoffs.

I very much disagree with his method for short field over the 50' obstacle. He wants to keep the airplane on the ground until he pitches up to Vx. This gives up way, way too much free ground effect energy. Your takeoff was appropriate for both soft field conditions and for short field conditions, and for short field over the brush at the end, and for any takeoff anywhere.

I have taken off exactly the way you took off in the video 50,000 or more times. I always take off that way. The use of low ground effect has saved my tin and skin numerous times. We don't know, for sure, what will happen on any takeoff. The time the engine quit, I was in low ground effect. It was easy to see that I had enough runway available to land on. At 200' at Vx or Vy, I would not have know this as surely. When the engine quit in the field I was spraying, five times, I had plenty kenetic energy of pressure airspeed to maneuver to a good landing area. I only scratched the airplane one of those times. I used many spray strips where we maneuvered around obstacles in low ground effect by using rudder to turn while keeping the wing level with aileron. This would be on both takeoff and landing when using the approach/departure with the crooked path.

The best way to get an aircraft out of any field in any situation is to get the nose or tail wheel off as soon as possible, get the mains off as soon as possible, and use low ground effect to accelerate as soon as possible, Now we are maneuverable, ready, whatever comes.

Notice in the newest, 2013. Practical Test Standards for both Private and for Commercial Pilot that the acceptable takeoff standard has changed from stay on the ground and rotate at Vx or Vy as appropraiate to accelerate in ground effect until Vx or Vy as appropriate. They won't admit it, but they now realize that they have been partly responsible for so many takeoff mush and stall accidents.

How are you doing with the "Safe Maneuvering Flight Techniques"? If you don't have "Contact Flying," send me your postal address and I will send you a signed copy. It goes into the background of the techniques much more than the e-book.

I am attaching some short stories I wrote in a Creative Writing Short Story Class I took for fun. Since I wasn't very creative, I wrote semi-true stuff from my past. I also attached a different organization of Safe Maneuvering Flight Techniques. One of the guys from the AOPA thread you started asked for my e-book. He reorganized it and sent it back to me. I think it was just some trick with the computer, but I don't know computers that well.

Jim

Rich, if you would have filed a flight plan.....[emoji23]

Rich, I have kinda been takin a break from opining on here for awhile, but have to say you did good!!
You took off, didn't bend anything and it felt OK to you!
I'm not to well with words and usually put most of my foot in my mouth sometimes.
I'm an old bastard that got away with lots of stuff they say you're not supposed to do. have flown a bunch of different birds, loved everyone of them.
Like PP low wings will fly just about anywhere.Had to laugh at the Bo taking off, I flew an old E-model with drop tips and vg's on it out of Yakutat when I first went there, It was the first low wing retractable in most of the strips around there, Yep I was a Dumbshit for even trying!!
Sure had fun tho. Orin Hudson gave me a few tips on how to get one off the ground and flying(he had about 12,000 hrs in Bo's) nothing he said was in any book?? (He and contact flying grew up together in different places doing different things, but flying the same!!??)
My dads last plane was a 150-150, 1959 model, hell of a little plane, Looked kinda funny with him and I in there as we had to fly with both windows open to get the doors shut, just no place for arms!!
Keep doin what ya like, and take everything ya hear for what it's worth??
Have fun, thanks for the video
GT
OH yes here is a little video from AK that might interest you for short field, lots goin on here!!
https://www.youtube.com/watch?v=WVR_HMAx5uc
My friend Don sent this!

Wow GT. Quite the vid! Whats bouncing behing it in mud in the slow motion? Did one of the people get hit, or is that a plane part?

The comments below the vid indicate that there were people standing at the end of the field and that one of them was run over but somehow survived. Always amazes me the chances people will take for no good reason (not talking about the pilots here--the spectators). At the end of the annual Marble fly-in, there are often folks on the road that crosses the end of the strip, watching airplanes come toward them. A couple years ago, I was already in the air building speed in ground effect when a pickup drove out on that road and stopped in the middle. I was plenty high as I passed over them, but sheesh, how dumb!

Cary

Ha Ha! Lot of big (and not so big) mud puddles passed as runways in AK in earlier times. There's a good reason why we learned non-POH use of flaps and the magic of ground effect to get in and out of places with heavy airplanes.

Gump

I read the AOPA posts and that is some funny shit. I like the one where the is saying "I wouldn't want your name in my logbook anywhere" I literally laughed out loud at that.

Nothing can be right unless it is in the POH, was what I took away from that string.

.

"I very much disagree with his method for short field over the 50' obstacle. He wants to keep the airplane on the ground until he pitches up to Vx. This gives up way, way too much free ground effect energy. Your takeoff was appropriate for both soft field conditions and for short field conditions, and for short field over the brush at the end, and for any takeoff anywhere.

I have taken off exactly the way you took off in the video 50,000 or more times. I always take off that way. The use of low ground effect has saved my tin and skin numerous times. We don't know, for sure, what will happen on any takeoff."








I could not agree more. I'm a touch shy of the 50,000 times, but 95% of the last 28 plus years flying has been from "unapproved surfaces". I always take off that way as well.

UpNorth

Before I die, I would like to see as much of this stuff as possible taught to as many pilots and instructors as possible. I hope we can get some kind of workshop going on this in the spring. Yes, there are a lot of expensive mountain clinics. No! they don't teach this stuff.

I'd like to ask some of our highly educated engineers and high-time graybeard pilots how we can reconcile the takeoff techniques mentioned in this thread with one or two of the laws of physics.

According to Wikipedia, the L/D or lift over drag (design efficiency, glide ratio, etc.) of the Cessna 150 is 7 to 1, which means that at maximum efficiency (level cruise flight) the 1600 pound airplane is making 228.5 pounds of drag. For the sake of discussion, I think it's safe to say that on a max performance STOL takeoff, with draggy flaps out 10 or 20 degrees, and at a higher AoA (flying at minimum speed with the stall warning almost chirping) we should have maybe 25% lower L/D, something like 5 to 1.

But "ground effect" provides a lower drag environment because of the cushion or downwash reaction or whatever. So let's say that the ground effect gives us back everything we lost from the flap drag and the high AoA, putting our Cessna 150 back up to 7 to 1 efficiency. 228.5 pounds of drag struggling along in ground effect on our short max performance takeoff.

Now let's look at rolling resistance. For the moment, assume smooth, level ground. Assuming that our wheel bearings are greased and not damaged, most of us can pull our Cessna 150 across the ramp with a lot less than 228 pounds of pull. Maybe 20 or 30 pounds of pull once the aircraft was rolling. Even if we hooked the 150 up to the back of a truck with a rope and a fish scale, and drove it down a long runway, I suspect that even at 60 miles an hour you would see far far less than 228 pounds of pull on that fish scale.

The reason for this, if ancient textbook memories serve, is that towing it down the runway there is NO induced drag - the drag created by the generation of lift. Because the WHEELS are carrying the weight of our 1600 pound Cessna, the wings do not have to make any lift or the lift-related drag. And wheels have a much higher L/D than wings... this is why the railroad is still the most energy-efficient way to move cargo.

To hell with the official "pilot operating handbook", the laws of physics seem to be telling us that an airplane will accelerate to climb speed faster if the wheels are supporting the weight until the moment we climb away. When you remove the induced drag (from lifting 1600 pounds off the ground) and replace it with a much smaller amount of wheel bearing drag and tire rolling resistance, you have less force resisting the acceleration of the airplane.

This example of course is based on smooth level ground, which we may not have out in the real world. So it would seem that there is some point where the height of the grass, or depth of mud, or surface texture favors the early liftoff and acceleration in ground effect... the textbook soft field takeoff. But it also seems that there would be an equal number of scenarios where you can take advantage of the lower drag of the wheels to carry the airplane weight, and wait till the last second to use the wings and their lower efficiency.

Now all of this theoretical physics seems to be in contrast to what many of you guys actually do out there in real-world conditions. My question for you is why and how does this work better than what physics would indicate?

Rich,

I'm bummed that you pulled the video though I certainly understand why you did. Sounds like you did a nice job flying. I'd love to see the video so I can post an informed comment on the AOPA site (no I'm not FAA). I don't have a whole bunch of hours like many of the AOPA "Pilots With a Capital P", but find that kind of sanctimonious attitude both irritating and hypocritical. I just deleted the rest of my rant.

My buddy and I share a 150. He's better with it than I am on short field ops though. You certainly have to know how to fly a wing.

Don't let the know it alls with no practical experience get to you.

Unless of course you aspire to do their kind of flying.

I'd love to see the video if it's posted anywhere.

Frank

EZ Flap,

I am a History and English teacher and both my math and science knowledge is marginal. I don't understand the physics of ground effect as well as others, I just know from many thousands of hours of experience that it works best for short field as well as for soft field from any surface. I think a lot of distrust of the basic low ground effect takeoff comes from allowing the aircraft to climb into much too high ground effect after liftoff. I think this error results from fear of, and lack of exposure to, low ground effect flight. Also, the percentage of increased performance in low ground effect is greater as the size of the engine involved becomes smaller. With normal engines on training aircraft, airplane and helicopter, tremendously greater acceleration is achieved in low ground effect.

The people who have done the most science with low ground effect are hydroplane or seafaring vessels that use a wing to get into and operate in low ground effect. The only number I understand, with their many involved charts and graphs, is that 40% of their lift comes from ground effect. They are much faster than regular vessels.

Again, I think many pilots who experiment with the roll it off verses the ground effect takeoff allow the aircraft to pitch up too much and attain ten to fifteen feet of altitude. There is a vast difference in acceleration in an aircraft trying to maintain six inches to three feet of altitude verses one struggling to maintain ten to fifteen feet altitude. The trick is to not think about climbing at all until at least Vy. The trick to maintaining low ground effect altitude is to move the stick or control wheel fore and aft dynamically. Like keeping longitudinal alignment with rudder, keeping level in low ground effect requires dynamic, proactive control movement. Control movement, not pressure. Proactive, not reactive. Dynamic, not static.

Crop dusters get to practice this 99% of the time. If not crop dusting, we need to fly down long runways at three feet, then two feet, then one foot. Don't try to keep the stick static. One foot is easier than three feet and vastly easier than fifteen. The closer we fly, the sooner we get feedback from being too low. No, it doesn't hurt anything to touch down.

After flying down the runway fast, which is easier, we need to practice staying in low ground effect at slower and slower speed until we are able to do it at slower than stall speed (hover taxi.) This skill is helpful on landing as well as takeoff. As with any control, the slower we go the grosser need be the control movement.

A major advantage of the low ground effect takeoff, especially in short field and/or high altitude work, is that we know how we are doing much sooner in the takeoff run. If we can't get a small airplane into low ground effect relatively early in the run, we need to abort. It is much more dangerous to wait until the last possible moment and then see if it will leap tall buildings in a single bound. Getting off earlier, in low ground effect, might just convince us to rudder turn around the obstruction or quit.

I appreciate your participation, EZ, you make us think. How are we going to make a good judgement if there is only one choice?

Contact

Good stuff Contact.

Gump

Interesting topic. Here is my take. Once air moves over the wing for any reason you will have lift and drag. The more wind moving over the wing the more lift and drag. The wing don't care if the tires are on the ground it will start lifting and creating drag, as this happens the wheels support much less of the weight. Once you reach flying speed you would have to hold the wheels on the ground by keeping the tail high and keeping the wings from producing more lift and on the case of a hard runway this might help build speed quicker If you kept the tail high and no flaps throughout the start. Once you drop the tail to increase the AOA you have all the drag and lift back. On soft ground with take off tail low and flaps your tire is not supporting that much of the plane weight the wing is. Keeping it on the ground is more drag than just getting in the air. If I had a hard runway I might keep the tires on it with tail high a bit longer to help build speed. But once in the air ground effect will help build the speed. As Contactflying pointed out this is not 15 feet up. It takes practice to do it right I still touch a tire every now and then it always seems to be when my wife is with me. She always wants to know if I was changing my mind about the takeoff. There are so many factors to consider that you have to have more than one way to skin the cat.
DENNY

I think I've told this story before, but the thing that made low ground effect takeoff a necessity for me and my troop, was Vietnam. My numbers are second hand, from my chew chief, but I believed him. We didn't reduce rocket, minigun, and chunker load to carry full (1700 lbs for 2.5 hrs endurance) fuel for a 45 minute trip to work the Chup Rubber Plantation way up the Mekong in Cambodia. My crew chief said we were at 12,500 or about 3,000 lbs over gross. This was four trips per day for about ten hours flying per day for about thirty days straight. Our Vietnamese allies were getting their clock cleaned. At least each trip shortened, more trips however, as they retreated back to An Loc where they were hauling wounded out in Chinooks.

Anyway, the AH1-G Cobra would not hover higher than six inches. We just thought forward, not really moving the stick at all. Very slowly, the helicopter began moving forward. Just before transitional lift, the skids would settle with power to the perforated steel plank runway. If enough momentum had been developed, you were then off into a six inch ground effect takeoff. Attempting to go higher before zoom reserve was established would cause rotor bleed, rotor deterioration, or what helicopter pilots sadly call, "losing turns."

Once beyond transitional lift and back into low ground effect, acceleration was very rapid to a speed at which climb could be accomplished without losing turns.

Any attempt to add collective (increase pitch in all rotor blades) would be the same as trying to pitch up to high ground effect in an airplane. Losing turns or slowing down is the effect. Losing turns or slowing down causes descent and loss of acceleration. A vicious cycle can develop. If we try to go up or stay too high, we decelerate. If we decelerate, we descend. We then pitch up even more, causing more deceleration, etc.

To be most effective, we need to stay in low ground effect where the wing, rotor or fixed, can fly flatter. Airplanes wings and helicopter rotors like to fly flat or down hill. Any aircraft, plane or helicopter or flying boat, flies much better in low ground effect than anywhere else. This is where top speed was measured until airplane manufacturers had to fess up. It won't fly that fast out of ground effect.

So, whats the quickest way to get into geound effect? 'Pop' 10 degrees of flaps? Start the roll with 10 or 20? This has been a struggle for me. I feel like no matter what technique i use, my mains are stuck until about 45 mph. Thoughts or suggestions?