Aviation Puts the Awesome in Sixth Grade Science


Sixth grade was rough for me.  I was 5’4” and clumsy, I read a lot of Heinlein, and I was much more comfortable around adults than my age peers.  I remember spending a lot of time wishing that there was some way that I could really impress the other kids with the deep thoughts that I was thinking.  But, alas, I never managed to do that.

Fast forward to a couple of weeks ago.  My son is now in sixth grade.  Thankfully, he’s much better adjusted than I was and at least as smart.  But he also longs for ways to demonstrate to his peers the awesomeness of the thoughts he thinks.  He arrived home one day and announced that he was to be “scientist of the week” in his science class.  He was supposed to do a science experiment and report on it in class.  He and I thought for awhile and hatched a plan.

On that Tuesday, the skies were clear and visibility was unlimited.  I met him at the doors of his school as classes let out in the afternoon.  I wore my flight suit.  (Because, of course, it’s always good for your classmates to hear that your dad met you at the door wearing a flight suit.)  We drove to the airport, preflighted a TG-7A motorglider, loaded our scientific instruments and implements of destruction into the aircraft, and launched for a piece of airspace out between Detroit City Airport (KDET) and Selfridge ANGB (KMTC).

FOD Experiment Posing

The idea was to take two balloons to 10,000 ft. MSL.  One out in the unpressurized cockpit and one sealed in a mason jar as a control.  We’d observe the experimental balloon every 1,000 feet or so and then measure it 10,000 feet.  We could also visually compare it to the control balloon in the jar.

I’m working on my CFI in gliders and,  if I have someone else in the aircraft (other than when I’m flying formation), I take the instructor seat on the left and the other person takes the primary pilot seat on the right.  (Air Force doctrine calls for the stick to be in the right hand and the power in the left and, because there’s only one throttle and it’s in the center, the PIC sits on the right side in the TG-7A.)  This means that I can let my son do most of the flying from right after takeoff until just before landing.  I get practice flying from the left seat while also honing my instructor skills while he flies.

I gave him the controls just after rotation and we flew north of the field and began to climb.  He circled up and I held up the balloon(s) for the camera, along with note cards with the altitudes on them.  At 10,000 MSL, I did the measurement, and then we pulled the throttle and circled back down and landed.

FOD Experiment Measurements

The experimental balloon didn’t grow as much as we thought it would.  We actually worried about that.  There was no apparent difference between the experimental and control balloons if you just eyeballed them.  But, when we measured, we found that the circumference did expand from 25.5 cm to 29 cm.  Assuming that the balloon is spherical (close enough), that’s a 41% growth in volume.  After (not before!) doing the calculations, we compared our results to the actual difference in atmospheric pressure for a standard atmosphere and found that the balloon’s expansion was within 2% of the 43% drop in atmospheric pressure in a standard atmosphere.


We did a PowerPoint presentation summarizing the experiment and he delivered it for the class on Friday.  It went over extremely well.  The teacher even called in the other science teacher to watch once the first slide with an aircraft on it popped up and made it apparent that the presentation was going to be special.

Lessons learned (among many others):

(a) It’s okay to have preconceptions about what will happen, but be objective about your data-taking and accept the data.  The best scientists know that it would be even cooler if the experiment had yielded results different from what you expected.  Isaac Asimov put it well:  “The most exciting phrase to hear in science, the one that heralds new discoveries, is not ‘Eureka!’ but ‘That’s funny . . .’”

(b)  Aviation captures imaginations.  The presentation made a huge impression in the class.  It held the class’s attention and even drew in the other teacher.  Every kid in the room understood the results.

(c)  You can become a legend at your school if you present photographic evidence that, at the age of 11, you flew a TG-7A nearly two miles high and back.

FOD and I will surely come up with additional excuses to incorporate aviation into his homework.  And, in the meantime, we’re spending lots of time flying for flying’s sake.  It’s nice having 100 lbs of willing student in the right seat so that I can sit left seat and practice my instructor thing for my CFI certificate.


Who We Are and What We Do: A Journeyman’s Letter Back to the Tribe

I’ve been thinking a lot lately about how I’m going to approach turning this weekend’s first airshow performance experience (and, frankly, this whole season) into Airspeed episode content.  This is big, huge, life-event stuff for me.  I’m still pretty tingly about having done it, even as I write this on the Thursday after returning.  I really want to get writing, but I need to let it simmer for awhile before really writing the episodes.

So you knew that it was going to start squirting out.  This afternoon, I undertook an intermediate measure.  I wrote an e-mail to the cast, crew, and friends of the Acro Camp movies.  Although I’m the putative mastermind and the guy behind the camera, I am very much a camper myself at heart.  I only made the movies because there were no casting calls by anybody else making them that I could answer.  So I made those movies myself with my friends.

I really needed to tell a core group of people what was on my mind.  I needed to tell people who really get it deep in their bones.  I needed to tell my tribe.  So the e-mail turned into a message that one who has gone far afield to seek his fortune might write back to the tribe.  To tell his fellow tribe members how different it is out in far-away lands.  And how he has carried the tribe with him.

Smarmy BS?  Maybe.  But it’s my smarmy BS.  And I’m pretty proud of it.  And it’s probably not smarmy BS, either.

You’re going to get the full energy of this experience in an Airspeed episode or two soon.  But, until then, I couldn’t think of a good reason not to share this with the broader Airspeed community.  You guys are, after all, a part of the tribe.


Ladies and gents of the Acro Camp community:

I discovered something this weekend.  A TFR is perfectly fine as long as they put it there for you and you’re in it, wings-up and burning free gas.

Long story short, I flew my first airshow this weekend in a hot box and a TFR over the waterfront at Rogers City (KPZQ) as Tuskegee 2 in a two-ship demo of TG-7A motorgliders.

I was supposed to be 3, but our No. 2 ship developed a bad mag on the way up and had to divert for MX.  3 did make it up, but the Sunday demo was cancelled for wind (bumpy as HELL for practice that morning and the gust ground-looped lead on the taxi for the second takeoff, so we knocked it off).  We returned to KDET as a three-ship, but got some passes in over town before departing.

For those not in the know, the TG-7A is a motorglider with a 59.5-foot wingspan initially flown by the USAF Academy.  Piper Tomahawk firewall-forward and Franken-glider behind.  The academy surplused out three of them in 2003 and the Tuskegee Airmen National Historical Museum in Detroit got them to use in training kids to fly and to raise awareness about the museum and its programs.  Out fleet represents fully half of the remaining flying fleet of TG-7As.

They’re yellow, they look great with big bank angles, they fly great in formation, and we can fill the sky in front of the crowd line with swooping longwings to great effect.  At the conclusion of the initial part of the demo, the solo ship (that’s me) does 180-aborts back and forth in front of the crowd between 0 and 300 AGL and then recovers.  The two other ships gaggle-climb to 1,000 AGL and go engine-out and glide back to recover, preferably on a taxiway right in front of the crowd.

We’re not technically aerobatic, but we bank big enough that you actually have to take the low wing’s dihedral into account to avoid the stinkeye from the FAA.

Anyway.  I know that you campers came to Michigan and experienced some really new sensations in a very public way and at a rapid-fire pace.  It changed every one of you in some way.  It might be hard to believe, but it changed the crew who watched and filmed you, too.  And the director/editor who re-lives it in his basement late at night as he watches from his perch out on the wing.

I told you during the camp that I’d never ask you to fly a camera rig that I hadn’t already flown myself.  I made good on that part.  But I did ask you to undergo that trial by fire of learning acro in the camp format when I hadn’t really ever had that experience and didn’t have a genuine sense for what that was like.  I’m not sorry that I did that to you.  In fact, I’m still kind of jealous of you.  But I still threw you into a deep end in which I had little or no experience.

But you need to know that I do put my stick and rudder skills where my mouth is, even if it is a little time-delayed.  I’ve only been flying these aircraft since March.  I got sucked in when I realized in the middle of my second flight that I was training for the rating (these things are in the glider category, so it’s new-rating time if you want to fly them PIC).  I picked up a commercial certificate with the glider rating on July 12 and got asked a couple of days later to join the team.  I went from 0.2 formation (in an L-39) and no real glider time to airshow demo team member in just a few months.

When you commit to fly a show, you’re committed.  The team can’t very well get a sub at the last minute.  You commit or you don’t.  And, if you commit, you suck it up and go fly to a high standard that involves being very close to other aircraft and constantly earning the trust of the other two guys.  Even when it’s bumpy as hell.  Even when you’re forced to land downwind because there’s a KC-135R blocking some other important part of the airport.  Perform.  Period.

I got an education.  I was reactive a lot more than I was proactive.  I have a lot to learn.  But airmanship like the kind that Don and Barry teach translates.  The pace, order, and mutual support of an IAC contest translates.  The camaraderie of an Acro Camp translates.  It’s all right there waiting for you when you need it.

I just wanted to let you know that you guys helped make this weekend possible.  If you think that I considered not flying the show, you’re right.  It would have been easy to bow out.  I was a brand-new glider driver whose media reputation probably gets him more credibility that his flying skills really deserve.  I was pretty goddamned scared and saw a lot of stuff that I’ve never seen before and was expected to figure out quickly.  But I’ve got a little piece of each of you in my hands, feet, eyeballs, and heart.  That – and lots of other stuff – made it happen.

We are a rare collection of people.  We demand of ourselves the willingness and capability to do things that aren’t easy.  We do them because they’re hard.  And because, if there’s fear in doing a thing, we also know the fear of not doing the thing and regretting that we didn’t take on the challenge.  This is who we are.  This is what we do.  And we will forever be different from the others among whom we move from day to day.  We are amazing people, every one.  And I’m insufferably proud to be a part of an intrepid band of humans who take on challenges like this.

The team is still working out some last-minute details, but, if things go as we expect and you’re in the neighborhood, stop by [airshow event and location withheld from blog post until confirmed].   I’ll be there.  Flying Tuskegee 3.  In the box.  Wings-up.  Being like you.

Invertor et vomens!  Smoke on!

- Dogbag

Tuskegee 3


A Pilot FAQ for Journalists – First Installment: Stalls

A few weeks ago, I posted in a few social media outlets that we in the aviation community do a lot of complaining about how badly the non-aviation media screws up aviation coverage but we really don’t do much to fix it.  We really ought to put together a FAQ or a wiki for the relatively few mainstream journalists who care enough to read up and get it right.

I got a lot of good feedback.  Enough that I think it’s a viable idea.  I haven’t decided yet whether to make it a FAQ or a wiki or something else.  But I figured that I’d put together an initial entry on a topic that most non-aviation journalists seem to get wrong as an example of what I’m thinking about doing.

If you’re interested in assisting, please crop me a comment on this entry.  And, if you have suggestions about this particular entry or about means to make the FAQ/wiki/whatever work, let me know those, too.

So here goes . . .

What’s a “stall?”  And why does it have nothing to do with the aircraft’s engine?

The general public understands that, when a car’s engine stops running in an unplanned sort of way, that engine has “stalled.” But “stall” means something completely different in the context of aviation.

A stall in an airplane usually has nothing to do with the engine. Sure, an airplane’s engine can “stall,” but aviators usually use some other word, such as “quit” or “stop.”

Let’s talk about how an airplane stalls. Airfoils develop lift by moving through the air. Airfoils include the wings on airplanes, the rotor blades on helicopters, and lots of other things. The control surfaces on airplanes and even the propeller blades themselves are also airfoils. Heck, a barn door can be an airfoil under the right circumstances.

We’re going to talk about some specific kinds of airfoils, namely the wings on airplanes. Generally, the aircraft engine rotates the propeller, pushing or pulling the airplane through the air and creating airflow over the wings. The wings develop lift when they interrupt the air, sending some over the top and some over the bottom. The air over the wings develops something called “laminar flow,” which is a fancy way of saying that the air on both the top and the bottom of the wing moves quickly and uniformly in the area very close to the wing.

The angle of a wing as it meets the airflow is called the “angle of attack.” When you tip a wing up into the airflow – when you increase the angle of attack – more air hits the bottom of the wing and there’s a greater pressure differential. Low angles of attack are good for cruising and that’s what you see when you see an airplane overhead that’s pretty much level and is on its way somewhere. High angles of attack are good for climbing. You can see an airplane with its wings at a high angle of attack every time you go to the airport and see them taking off.

With us so far?  Good!

Imagine what would happen if you increased the angle of attack a lot. Thirty or forty degrees or something like that. At some point for every wing, the airflow is simply smacking the bottom of the wing and not enough air goes over the top of the wing to keep that laminar flow. Eddies and turbulence build up on the top of the wing and the laminar flow just dissolves.

At that point, the wing won’t fly anymore. It’s not developing lift. That angle of attack for any given wing is the “critical angle of attack.” When a wing exceeds its critical angle of attack, the wing is “stalled.” When aviators talk about an airplane being stalled, they mean that the airplane’s wings have exceeded the critical angle of attack and that the wings aren’t developing lift like they otherwise might. What does that look like? The airplane’s nose is usually very high and its forward speed is very low.

Technically speaking, stalls are entirely dependent on the angle of attack of the wing.  But airspeed (the speed of the airplane through the air) is a pretty good proxy for that angle of attack.  The slower the airplane is moving through the air, the less air is moving over the wing to create lift.  And the greater the necessary angle of attack if the airplane is to keep flying at the same altitude.  So sometimes pilots talk about stalls in terms of airspeed, specifically “stall speed,” below which the airplane will stall.  The slower the airspeed, the more likely it is that an airplane will stall.

Stalls can be bad if they occur when the pilot isn’t expecting it, so student pilots and experienced pilots alike practice stalling their aircraft so that they know how to recover from stalls. The private pilot practical test standards require that an applicant for a private pilot’s certificate for airplanes be able to stall an airplane – and recover – with a lot of power or with little or no power, and in turns either with or without power at bank angles of up to 20 degrees.

Stalls are bad at low altitude, such as when you’re taking off or landing. It generally takes some altitude in order to recover from a stall – about 100 feet in many aircraft in the case of a power-off stall. That’s altitude you might not have.

Stalls can also lead to other bad things. One of them is a spin. A spin happens when the airplane is stalled and “uncoordinated.” An airplane is uncoordinated with the tail is not where it’s supposed to be – when the pilot doesn’t use the rudder to keep the stalled airplane from rolling in the direction of the wing that is the most stalled. Too much rudder produces a “skid” and too little rudder produced s “slip.”

If you stall and you’re sufficiently uncoordinated, one wing or the other will drop and the airplane will start falling in a lazy spiral. The spiral will be in the direction of the wing that is the most stalled. The other wing, the one that’s less stalled, will be flying just enough to keep the rotation going. It’s called “autorotation.” Being in a spin is very unpleasant if you’re not use to it. There’s a lot of green in the windshield and the airplane is turning at an increasing rate..

Stall and spin recovery isn’t particularly difficult. The pilot pushes on the yoke or stick to decrease the angle of attack and get laminar airflow over the wings.  That’s usually enough to recover from a stall that hasn’t developed into a spin.  If the aircraft has begun to spin, the pilot must usually use the rudder to stop the autorotation as well.

Aerobatic pilots go up and have fun with stalls and spins.  You might have seen aerobatic pilots at airshows performing maneuvers called “snap rolls,” “falling leaves,” “avalanches,” and other maneuvers with equally exciting names.  These maneuvers have stalls and spins as essential elements.  They look dramatic from the ground and they’re fun to do in the airplane once you’re received enough training and as long as you perform them at altitudes high enough to recover if you goof it up.

The way stalls get into the news – and the way most members of the media get the terminology wrong – is when a stall results in an accident that gets reported. As you can imagine, an accident could easily occur if you stalled an aircraft so close to the ground that you didn’t have enough altitude to recover. That’s doubly true for spins, because spins usually take something like a thousand feet in which to recover.

If a stall or spin results in an accident, it’s most often in the traffic pattern of an airport.  In the pattern, aircraft are moving more slowly and are turning and otherwise maneuvering to take off from, or to land on, a runway.  The most common stall or spin accident in the pattern is a spin on the turn from the base leg to the final leg.  That’s a 90-degree turn that begins when the pilot is flying perpendicular to the end of the runway and the pilot turns to point the airplane at the runway in order to land.  Sometimes wind or distractions cause the pilot to be further away form the final approach course than the pilot planned to be, so the pilot banks further than the pilot should or tries to increase turn rate using too much rudder (a “skid”).   If the pilot allows the airplane to get too slow at this point and the airplane stalls, the uncoordinated state of the airplane can lead to a spin at low altitude.

The aviation community knows a lot about stalls and spins in the pattern.  We pay a lot of attention to the accident reports so that we can learn from them.  Flight instructors work hard with student pilots so that they know how important airspeed and coordination are in the pattern.

Journalists sometimes report on an accident saying that the engine “stalled” when, in fact, the airplane was stalled all right (its wings had exceeded the critical angle of attack), but the engine was just fine when the airplane interfaced with the planet. The actual event that the reporter misreported was probably an aerodynamic stall and/or spin in the pattern or on takeoff or landing. Reporters who get this wrong do aviation a disservice because each time they do it, they cause a few hundred more non-pilots to believe that general aviation aircraft are mechanically unreliable. When it was actually pilot error of some kind.

So, if you’re a member of the media and someone tells you before you go on the air that an aviation accident involved a stall, inquire further and find out whether it was an aerodynamic stall. If your source is a pilot or an aviation official, chances are good that he or she won’t use the word “stall” unless it was an aerodynamic stall. If the engine quit, they’ll usually say that the engine quit. And if you ask them to clarify, you’ll be an instant Einsetin to them because you’ll have clued them in that you recognize the difference.

If you’re a pilot or aviation official with the solemn job of briefing reporters on an accident or incident involving an aerodynamic stall, please take the time to explain what an aerodynamic stall is and point out that it has little or nothing to do with the engine.

And if you’re a member of the non-flying public, recognize what aerodynamic stalls are – that they generally have nothing to do with a powerplant or any other function of an aircraft. And that pilots train long and hard to avoid situations in which stalls occur, recognize their onset, and be always ready to recover from the rare unexpected aerodynamic stall.

Aerodynamic stalls are very rare in everyday flight operations. Unless you’re a pilot who’s training or performing aerobatics, the odds are very small that you’re ever experience one – even if you fly commercially every day of the week and on weekends, too, your whole life. They just don’t happen much.

Stalls are a natural result of the behaviors of airfoils under certain extreme conditions. Aerobatic pilots put them to use in graceful and energetic performances around the world at airshows and other events. Student pilots train to recognize them and recover from them so that they can fly safely for decades to come.

Red Tails Disappoints

As a new-media and social-media guy, you build audience by getting excited about your subject matter and getting the audience excited, too. But you build credibility when you point out the ugly among the good. I really wish that this post wasn’t going to have to be about credibility. Or about ugly. But it is.

I just got home from seeing Red Tails. I had heard that the film had received less than stellar reviews, but I made it a point to avoid others’ opinions and go see the film for myself.

I’m so disappointed. It was like watching a train wreck in slow motion.  Here’s what I saw. [Read more...]