Sunday, February 13, 2011

Flying Inside the Box

What did we do before Google Earth?  Did we have paper charts and maps of stuff like roads and fields and stuff?  Did we have scales to everything when printers and copiers changed the size of everything?  I don't remember.  I have a vague recollection of considerably more work.

Our Jackson box is shown above, parallel to runway 6/24, which puts it perfectly over swampland but makes it a bit of a bugger to fly because it isn't square with all the wonderful section lines here in Michigan.  And runway 14/32 isn't quite orthogonal to it either.  Runway 32 was extended since this photo; the threshold of 14 is now just west of the middle of the box.  It can be hard to keep flight lines parallel to the box edges when not in a position to clearly see 6/24 from the air.

Runway 14/32 is closed during the competition, but 6/24 stays open for business at all times.

Combine Google Earth with a site like Calculate distance, bearing and more between Latitude/Longitude points (and there are many others, but this one did exactly what I needed) and laying out a box is really painless.  The site calculates distance between points specified by Lat/Long, and also gives the bearing between points and extrapolates points from known positions, given distance and bearing.  All the equations and code are explained also for those who need it, but I just used the plug and play features.

This box is exactly where our box was positioned last year, but I wanted to check it and re-plot it.

A competition aerobatic box is 3300' square (which is a smidgen over one square kilometer).  The east corner is positioned so that the box will sit northwest of runway 6/24 and west of the buildings between the runway and I-94 to the north, with at least a 164' buffer zone from edges of the aerobatic box to runway and buildings.

I set the east corner where it was last year.  The Lat/Long was obtained with a Google Earth marker; I projected the 3300' line parallel to the runway to obtain the south corner, defining the "front" of the box (SE edge).  Then adding 90 degrees to the bearing and projecting north and west corners was painless.  The website gives mid-points between lat/longs automatically, so the middle is easy to find.  I simply typed the Lat/Longs into Google Earth markers, took the screen shot into MS-Paint and threw the box lines in.  Nothing very sophisticated but this is all the FAA needs for depiction and is quite accurate.

We'll use a GPS when we place the box markers out in the fields, and the box will be within a few feet of a perfect size.  From the air it looks very nice and square, however cockeyed to the rest of Michigan as we know it.

The box goes to 3500 AGL, or almost exactly 4500 MSL at Jackson.  The lower limit depends on category, and the Unlimited base is only 328' AGL.  Since the box crosses I-94 just a little, there's a small wedge cut out of the north corner over I-94 which might only affect an Unlimited flight where the base is kept at 500' AGL.  The base for Advanced is 800' AGL and higher for other categories, so they are not affected.

We have line judges at the east and south corners, watching the SW and NE edges as well as the front edge along the runway.  The judges sit safely clear of 6/24 on the south side, almost box center and parallel to the front edge of the box.

So this picture will go in with the 7711-2 form, some pilot procedures documentation, and a page or two of IAC standards, and we'll see what the FAA folks need, if anything else, to approved this year's competition box.  It will be nice to have things in place early.

Wednesday, February 9, 2011

Aerobatics Training vs Upset Recovery Training

Ever since I started flying aerobatics in 1999 I heard complaints about the schools that promoted "upset recovery" courses vs. those that taught aerobatics for aerobatics' sake.  The "upset recovery" courses were considered a scam, because for far less money (and the same amount of training) the things taught in basic aerobatics were exactly what the "upset recovery" courses did.

Well, almost.  It is 80% marketing and 20% actual differences.  The schools doing aerobatics training just need to adopt the marketing lingo - and make a few minor adjustments to the syllabus - to pick up the "upset recovery" training market.

There are only three basic conditions in which one may arrive having departed controlled flight momentarily.  First, and most common, is nose-low high-speed, and that could be upright or inverted.  Wake turbulence encounters can put the aircraft upside down, nose-low very quickly.  Second, the aircraft could be nose-high, slow speed - but still flying.  Third, a stall situation (normal or accelerated) can quickly develop into a spin, and that spin could be upright or inverted depending on how the aircraft got there and use or abuse of controls along the way.

Basic aerobatics courses almost always include loops, rolls, hammerheads and spins (the four fundamental maneuvers from which most competition maneuvers are derived).  Once a person has looped and flown Cubans or Hammerheads the recovery from nose-low conditions, upright or inverted, has been taught, with appropriate power reductions if an over-speed situation is imminent. One learns that pulling the power, rolling upright, and lastly loading the airframe sufficiently during recovery (in other words, don't be a wimp about pulling the nose up, but don't pull the wings off either) will arrest a high-speed situation nicely.  The aerobatic maneuvers also put the aircraft at very low speed with the nose high on the tops of the loops and hammers and Cubans and such, and one is taught tricks like yawing out instead of pitching out (the hammerhead vs. the humpty).  Finally, we spin every which way and learn to recover, whether upright or inverted.  It's all right there in the basic aerobatic maneuvers, and paying extra for an "upset recovery" course is just a waste.  Remember that the hardest thing for most people is not the business of flying the aircraft but just the ability to keep up with its attitude and recognize the situation.  This can be physiologically taxing, and basic aerobatics gets a pilot though the learning and exposure curve.  Any upset recovery course has to do the same.

Well, mostly, but that isn't the whole story.  If a pilot isn't too concerned with flying aerobatics long-term then the emphasis can shift for a dedicated Upset Recovery Course.  First, a deemphasis on coordinated aerobatic maneuvers.  In other words, if you aren't going out to loop and roll other aircraft, then don't worry so much about making them pretty.  But you still will need to loop and roll and hammer and Cuban at least a little bit to get used to seeing the world in unusual attitudes.  You just don't have to be worried about doing it very smoothly.  The emphasis is on attitude recognition, not on smooth aerobatic flying skills. Secondly, recoveries can take on intentional uncoordinated aspects as the emphasis shifts to minimum altitude loss.  Yes, one still cuts the power, rolls blue-side up, then pulls to level while bringing power back in as necessary, whether in a simulated wake turbulence encounter or on the back side of a Cuban eight.  But in the upset recovery course stomping excessively on the top (blue side) rudder while rolling to get the nose up is an option, where in aerobatics it would be considered sloppy.  Finally, all aerobatic trainers used for upset recovery courses will roll faster than non-aerobatic aircraft, so simulated limitations to roll rate are appropriate for upset recovery courses.  So are simulated limitations on rudder effectiveness for spin recoveries.  We try to make the little aerobatic hotdog airplane respond as much like a non-aerobatic bird as possible.

So my local school (Berz) is planning to develop a webpage that describes aerobatic training programs that we already do, including upset recovery training, having recognized that those marketing these courses as something special are attracting locals half way across the US to get something they could get very well right at home with us for half the cost.  We just didn't explain it well, because we thought it would be evident that any school teaching competition aerobatics could do a darn good upset recovery course also.  To the general flying public that isn't necessarily obvious, and, in fact, it might sound a little scary - many who want some upset recovery training are forcing themselves to do it because it will be good for them, not because they want to fly aerobatics long term or enjoy being upside down.

1) Don't run out of airspeed, altitude and ideas simultaneously.  2) Subject to point 1, keep the brown side anywhere you want it to be.  If you like down, then we'll teach you to get it back there safely.  If you like anything but down, we'll have you flying competitions soon.

Saturday, February 5, 2011

Why Aerobatics? And why compete?

Yep, that's me in the Pitts, awesome picture by a grinning Victoria Neuville who was snapping shots of everything including herself when not actually flying.

So here's a blog about setting up an IAC sanctioned aerobatic competition and some of the details of flying aerobatic competition maneuvers and how contests and judging and flying it all works and maybe it begs the question of why we do this in the first place.  What sort of crazy impulse would inspire someone to depart "reasonable" flight attitudes for the world of high g's loads, weird attitudes, spinning horizons and potential nausea?  And then do it in front of others?

Here are a few reasons why aerobatics are cool.  There's a lot of press about this right now (AOPA articles and such) and a movie in the works (AcroCamp) and more.  It seems to be in a renaissance - after years of backing away from spin demonstrations and accelerated stalls in the Practical Test Standards, the benefits are again appreciated.

1)  Aerobatic experience helps maintain a broad field of vision and attitude awareness through fast and extreme pitching or rolling. Without experience, vision narrows and blurs and awareness of aircraft attitude is often lost when things happen quickly - especially if unexpected.

2)  A theoretical understanding of sensations and control inputs for unusual attitude recovery is rarely sufficient to accomplish the task if needed. A little aerobatics will develop appreciation for the forces – both on the yolk and on the body – to minimize altitude loss and recover from all attitudes safely and without bending the airplane.

3)  Aerobatics training will help to gain a lot of faith in the aircraft – it is generally tougher than we are, but some experience will help the nerves and the nausea abate.

4)  After some aerobatics, the comfortable level with “normal” flying on turbulent or uncomfortable days goes way up. Compared to spinning and rolling and pulling serious g’s, what’s the big deal?

5)  Aerobatics training exposes the pilot to safe operations within the full operations envelope - from red line to stalls, normal and accelerated.  The safety afforded by this experience for normal aircraft operations is invaluable.

6)  Who knows, this figure skating in the sky might actually be addicting. Advanced aerodynamics and energy management in spades. Comfort and control in any attitude. Grace balanced with forcefulness. Freedom. Fun. And membership in the club of a rarer but special breed of pilots that constantly challenge themselves to fly more precisely and more completely, whether in competition or just for fun.

There's flying aerobatics way up high for fun.  Then there's learning the precision of competition maneuvers.  Then there's doing it in about 2000 feet of vertical workspace with a 1500 foot minimum altitude.  Then try to keep a sequence of maneuvers in a 3000 foot square box over the ground (it looks like a postage stamp).  Then throw in people watching and messes with your mind...and you've got a competition.  Fast thinking and precision flying.  Besides great flying skill development, the surprise of competition acrobatics is the camaraderie and support of all the other pilots.  It's a great group.

The neat thing is that it doesn't really take very long to get started.  Some fly their first competition after a half-dozen lessons.  You can fly it with a safety pilot, so jump in the deep end two feet first and have fun.  You'll be glad you did.

Or just get some basic aerobatic training with advanced spin recovery work and be a better pilot for it.  It's unusual attitude recovery and more.

Competition Aerobatics - Basic maneuvers and this year's Primary Known

Time to start discussing what we fly in competition and how we fly it.  Part one: the basic maneuvers.  Here's this year's Primary Known routine, which covers three of the four basic competition maneuvers and a combination maneuver, as well as the aerobatic steep turn.

The diagram above (an Aresti depiction) shows six maneuvers, numbered in the order flown.  Maneuvers always start and end in level flight (true for all aerobatic categories), and start at the dot and end at the line.  While the maneuvers are flown in order, typically depicted top to bottom, the aircraft may in actuality hold altitude throughout.

There are only four basic aerobatic maneuvers which alone and combined form almost all competition maneuvers:  the roll, the loop, the hammerhead, and the spin.  There are just a few other maneuvers that don't neatly use or combine these four.  One example is the aerobatic steep turn, which is included in this Primary Known routine.  Straight lines can go horizontal, vertical or on 45 degree uplines or downlines.

Each of the six Primary Known maneuvers include challenges:

1.  The 45 degree upline.  Really a combination of 1/8th loop figures with a straight line section. This is used to slow the aircraft to near the stall speed, and is tougher to fly properly than it looks.  The radius of the pull up to the 45 line and the pitch back to level flight should be the same, which means a harder, faster pull to the 45 and a slower pitch to level to get the same apparent radius of the partial loops at beginning and end.  The pull into the 45 upline can easily hit 3 g's and the push back to level may be near 0 g or slightly negative.  During the climb the climb angle is judged not by track but by the zero-lift line through the wings, but the horizontal flight in and out is judged by flight line compared to the horizon, so that the slow flight at the end requires just enough nose-high pitch to hold altitude.  During the climb the deceleration changes the p-factor and thus the rudder input to hold heading increases constantly.  And you can't see anything over the nose so this is mostly flown looking out to the side.

2.  The spin. This is a one turn power-off spin, entered from level flight.  After the spin rotation ends the aircraft should continue to pitch down to a vertical line before the initiation of the quarter-loop recovery to level flight.  Problems: when power is reduced to idle in the level flight leading to the spin entry, the rudder input changes dramatically to hold heading (as the p-factor goes away); the pitch changes to hold a horizontal flight path up to the point of the stall (no climbing or sinking into the entry);the stall, drop of the nose into the spin and rotation should all start simultaneously, without the nose jerking up at the moment of the stall; the rotation should stop at one turn exactly, with no continuing yaw, followed by the nose pitching down to vertical; the recovery, while not hard, requires a pretty good 3 to 4 g sort of pull to hold the speed in check.  There's a lot here going on pretty fast.

3.  The half Cuban eight.  This is a combination of two basic maneuvers - the loop and slow roll (known to judges as an aileron roll to differentiate it from snap rolls).  5/8ths of a loop (which should appear round from the ground) is stopped momentarily at the inverted 45 downline, then a half-slow roll upright is followed by a little straight flight on the 45 downline before pulling to level flight.  The half roll should appear to be placed in the middle of the 45 degree downline, which is a trick as the speed is increasing throughout - it takes longer to draw the inverted portion of the line before the roll than the upright portion after the roll before the 1/8th loop pull to level.

4.  The loop.  This is supposed to appear round to a ground observer, which means the pilot has to adjust the rate of looping to compensate for speed changes in the aircraft and the effect that any wind might have to distort the loop.  Oh yeah, it is supposed to stay on heading also, with no rolling tendencies anywhere.  Not all that easy to do well!

5.  The aerobatic steep turn.  This is a roll to more than 60 degrees of bank (we usually shoot for about 70 degrees), then a stable, level steep turn, followed by a roll back to level.  No turn should happen during the rolling and no rolling should happen during the turn.  Tougher than it looks to coordinate properly and keep level.  We usually cheat with just a little "top" rudder to help hold altitude without having to pull more than 3 g's or so.

6.  The slow roll (judges call this an aileron roll).  This is a once-around roll where the aircraft is supposed to hold a constant pitch attitude and heading while rolling, which means lots of rudder and elevator input changes through the roll to keep the nose in line.  Again, much tougher to fly well than it looks at first blush.

Primary routines do not include hammerheads.  I've tossed an Aresti diagram here without explaining symbols as such, so some future blogging will include an explanation of these things, but I wanted to throw the easiest routine up here for starters and discuss why even the basics are challenging and interesting.  The diagram above is largely self-explanatory, but we'll cover more details later.

There's much more to discuss, but enough for now.  We'll break down Aresti figures and scoring methods and some judging standards in a later blog entry.

Happy looping - Don

Thursday, February 3, 2011

On the IAC Calendar

JACKSON, MI here we come!  July 9-10, 2011: The Michigan Aerobatic Open 2011.  Competition in all power categories: Primary, Sportsman, Intermediate, Advanced and Unlimited.  More on that in a subsequent blog.  Practice days July 7 and 8.

First progress has been made on a huge to-do list provided by the IAC in preparation for the Jackson competition.  If you are an IAC member you can find it here.  Heck, I think the link works even if you aren't an IAC/EAA member.

The airport is planning on us being there, and I had a great conversation with Kent Maurer, airport manager.  Kent is a retired police officer in something like his 8th year of airport management and loves it.  He does pretty much everything from administration to mowing and spent a lot of time on the plows this week.  I'm looking forward to meeting him in person soon.  Kent had anticipated our contest dates and posted them on the Reynolds Field calendar already. Thank you!

I then spoke with Dave Flynn, airport tower chief.  Dave flew in the military (C-130's and such) and has some great stories from those days.  The kind of guy that deserves an uninterrupted session over a beer or three, and I really hope to get that opportunity.  Dave likes having the acro gang around.  He said "they always know where they are coming out of the box" which leads me to believe that the general flying crowd doesn't always know where they are.  He mentioned the typical nice top view of an Extra diving out of the box on a right downwind to 24 in a steep bank and descent to the runway and remembers clearing a guy on a 3-mile straight-in for 24 for landing #2 behind an aerobatic something or other that was just coming out of the box.  The guy on final questioned his judgement; Dave told him he might get a glimpse of the lead aircraft exiting the runway if he got there in time.

Which brings up a point: aerobatic competitions typically do NOT close down the hosting airport.  In fact, we love having people fly in to watch.  At Jackson there is a lot of fly-in airport restaurant traffic during the event, just like any other weekend also.

The hosting airport will adjust traffic patterns if necessary and will stay open for business.  The box at Jackson sits just north and parallel with 6-24, over the top of the north end of runway 32, which closes for the competition.  If runway 24 is in use the non-competition folks fly a regular left hand pattern.  The competitors leave a high-post position south of the field well above the pattern and fly around the east end of the airport and enter the box from the northeast on the north side of the runway.  After completing a routine, a competitor will leave the box, enter a right downwind for 24 and land with instruction from the tower.  If runway 6 is active, the pattern reverses, with non-competitors flying right traffic to 6 to stay south of the field and competitors leaving the box in a left downwind for 6.  While above the pattern and in the box the competitors are on frequency with the chief judge.  When in the pattern climbing out or leaving the box to land the planes switch back to the tower.  The tower can talk with the chief judge at any time.  It all works rather smoothly.

The runway sets a "dead line" that competitors dare not cross for penalty of zeroing their routine, and most of the competition flying has a base altitude well above runway traffic, so the competitors simply don't get in the way.  The non-competitors taking off and landing may be a little self-conscious having a group of judges sitting under tents next to the runway, but they really don't have time to watch non-competitors much.

Finally, I am obtaining box information from last year and preparing to file the docs required to have the same aerobatic box at this year's competition.  I spoke with a very helpful operations inspector at the East Michigan FSDO (Willow Run) today and know what steps to take to complete all that - the form 7711-2 and supporting documents.  I'll post some of that stuff here as I get it.

I'm going to see if Nancy will write something for this after she makes contact with the local EAA chapter and starts to work on volunteer staff, starting with recruiting a chief judge.

More soon.  We'll be working on sponsorships in February also - that should be interesting!