STOL Techniques-from an Article by Mike Vivion

[JimC]

"I wish I had been smart enough to study physics more".

Me too.
Physics is fun though. I spend a good bit of my time working on the biomechanics and flapping flight mechanics of extinct flying reptiles called pterosaurs. The interaction of the two is fascinating.

Here I am out in my front yard holding the left humerus of Quetzalcoatlus northropi, one of the largest animals that ever flew (wingspan about 34 feet). Shoulder is in my right hand; elbow in my left. You can learn a bit about aerodynamics from studying these critters.

 

[CubCruiser]

I find my very limited understanding of physics to be very helpful when teaching practical flying techniques. As an example, the FAA version of a short field takeoff defies practical thinking. Stopping when moving only to hold the brakes before take off has never made any sense except to pass a check ride.

I wish I had been smart enough to study physics more.

sj

Agreed. And furthermore, short fields are often soft and soft fields are often short, yet we’re supposed to teach them as two separate entities.

 

[bob turner]

I have always wondered why the FAA separated short and soft field techniques. I do not seek operation on either, but when confronted with an off-airport operation it is usually both, and often the "soft" is also bumpy and sometimes smelly.

I like Jim's front yard.

 

[BC12D-4-85]

Short.....soft.....skis? Add any appreciable power and away we go! If the tail touches that causes drag.

How do the FAA's guidlines deal with that? See page 7-5 for a brief guide: https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/seaplane_handbook

Gary

 

[DENNY]

Soft field and short field are similar but approached differently. Soft field primary attention is to decrease weight on the gear by early AOA increase and use of flaps, this will increase the takeoff distance. Short field attention is given to getting too rotation speed with least amount of drag before perfect timing of rotation and flap application. As usual with FAA training/exams it is best to learn the standard, complete the test to standard, then go learn real world flying. In true off field flying the two are sometimes blended. Understanding how to properly unweight the tires is important especially in a world that students are trained not to use flaps for takeoff. Don't get me started on that one.
DENNY

 

[sj]

"I wish I had been smart enough to study physics more".

Me too.
Physics is fun though. I spend a good bit of my time working on the biomechanics and flapping flight mechanics of extinct flying reptiles called pterosaurs. The interaction of the two is fascinating.

Here I am out in my front yard holding the left humerus of Quetzalcoatlus northropi, one of the largest animals that ever flew (wingspan about 34 feet). Shoulder is in my right hand; elbow in my left. You can learn a bit about aerodynamics from studying these critters.

That is crazy.... and "humorus" first that you have one of those laying around your house, and second the wingspan....

sj

 

[JimC]

"and "humorus" first that you have one of those laying around your house, and second the wingspan...."

Well, its actually a research grade cast. The actual fossil materials are stored at the J J Pickle Research Lab at the University of Texas at Austin (I'm in west Tennessee). We try not to handle the fossil materials any more than absolutely necessary because they are extremely fragile, so make casts of the originals. I've got lots of this stuff lying about the house - much to my wife's disgust.....

Here on the hood of my car is a left wing and shoulder girdle of the small morph of an adult Quetzalcoatlus (4.8 meter wingspan). And in the background against the windshield, a head, neck and torso of a juvenile Brazilian pterosaur called Anhanguera piscator (5.05 meter span).

The animals were quadrupedal on the ground - the inboard 'half' of their wings served as their front legs. And to stay somewhat on topic, they were STOL specialists, launching from a standing start with their hands (front feet) the last part of their bodies to leave the ground. Q northropi stood about the same height as a giraffe, but had a tiny body.

 

[JimC]

SJ, I notice you're from northwest Arkansas.
Did you know Sam Cordrey who owned Sam's Aircraft?

 

[sj]

SJ, I notice you're from northwest Arkansas.
Did you know Sam Cordrey who owned Sam's Aircraft?

He died the year before I moved down here I believe. His business is still going, not sure who owns it now but a lot of folks use it.

sj

 

[JimC]

He was my first cousin. I think his former employees own it now.

 

[WindOnHisNose]

Mike, nicely done, as usual!

Mike has agreed to speak again at the Great Minnesota Aviation Gathering, to be held on Friday and Saturday, May 16-17, 2025, at the Buffalo Municipal Airport (KCFE). His topics: 1. Ski plane flying; and 2. How To Get Found.

Randy

 

[sj]

He was my first cousin. I think his former employees own it now.

That sounds right. It's likely where I will go once my current local option is no longer available.

 

[JimC]

Sam did really good work.
I expect they still do.

 

[RedOwlAirfield]

I wish I had been smart enough to study physics more.

sj

SJ;

You're not missing out on anything. My sister had postgraduate degrees out the wazoo - in physics. Not to speak ill of the dead but she was possibly the stupidest person I ever knew. To be fair she was that way before she studied Physics, but it sure didn't get any better the more degrees she had. To the point, "Smart" is most definitely not a prerequisite to study physics successfully.

Of course I was a truck driver, so consider the source.

 

[bob turner]

There are different kinds of smart. One kind that very few folks possess is the ability to do well in the study of physics.

 

[JimC]

Bob, I'm not sure I agree with that. Most of the people I know are kind of talented at physics. Jörgen for example ain't no slouch. I'm impressed with what he has done with skatesailing.and dragon sails.

 

[mvivion]

All I can say about that is: In aviation, physics bats last.

 

[JimC]

Would you elaborate on that please?

 

[bob turner]

I personally am not a great physicist. I think the only way I got my degree was by memorizing derivations I really didn't understand. I have, and had, friends who had intuitive feel for such things as Green's Function, but I was not in that club. I did get quite good at integral transforms, but I am convinced that there is a group of folks out there whose brains just operate in esoteric areas far beyond my expertise.

Nevertheless, the advanced study of physics at the graduate level in fact does require "smarts" beyond the average. You could conceivably make the case that a person who is not smart could get a college degree, but it becomes far more difficult to make that case when you are talking about advanced degrees in science.

 

[BC12D-4-85]

Locally, physics was applied to the University ski hill. Back in the '60's we'd ski from the top to bottom without injury. They even had a jump to go airborne. Then someone did a Humpty Dumpty and was injured on a sled.

The Physics department determined if the hill's available height for use was shortened, the kids couldn't achieve orbital velocity on the way down. Then plastics improved over the previous inner tubes and today they are back to required speed.

Gary

 

[TR Dunn]

Those that shun the science of physics are still bound by its “laws”. Unfortunately, they lack the understanding of “why things do what they do” and learn mostly from trial and error versus those who study the science and apply its “laws” to predict an outcome. As simple as two kids competing to be the first on the dock, jumping from their rowboat as it approaches. The one with an understanding of physics stays dry, the other does not.

No physics, no flight…physics is integral from design, to materials, to flight. One cannot correctly rig a set of floats, skis, or a bi-plane without physics. Use a torque wrench? Physics. Fly an aircraft? Physics. I introduce physics at an appropriate level of understanding to all I teach. To fully exploit the science of flight, one must know why the machine does what it does, and for that, one requires at least a rudimentary level of understanding and ability to apply the science of physics. Those who do not are merely along for the ride.

TR