It’s as clear in my mind today as the day I saw it circa 1960. My young eyes were riveted on a red and white sunburst 450 Stearman with a checkerboard tail. It was smoke, noise, and grace in the blue sky of a summer air show.  It was great.  Cuban eights, four-point rolls, loops, and all sorts of stuff that looked like great fun do to.  It was Bill Adams at work between 20 and 500 feet above runway 3-21 at the Bloomington Municipal Airport in Illinois.  After his performance, he taxied up on the grass to the crowd line rope and shut down the big P&W. I watched the prop wind down and his hands take off a leather helmet and goggles revealing his face.  I just stared at him in awe.

My grade school buddies had heroes like Stan Musial, Johnny Unitas, and Elvis.  As far as I was concerned Stan, Johnny, or Elvis could have never even gotten a 450 Stearman off the ground, let alone do what Bill Adams could with one.  So my heroes had a slightly different requirement, I guess.  Besides Bill Adams, other heroes included Hal Krier (Great Lakes), the Cole Brothers, and anyone else who could get one of those big Stearmans upside down and back again.  I just kept visualizing doing that myself.  I built models and pretended to fly them.  I would walk around the yard holding a model Stearman upside down in my right hand.  Then with my right eye pressed up to the little fuselage, try to look through the even smaller windshield to “kind of see” what it was like to fly aerobatics in a Stearman.  (You do what you have to do as a twelve year old farm kid.)

About 30 years later, I finally got to do what I had dreamed of since childhood. It was worth the wait.  Not only does it look neat, I strongly believe aerobatics makes pilots better in many ways.  To name a few, it improves situational awareness, safety issues, finesse, timing, feel for the airplane, cross check speed, and our abilities to recover from unexpected attitudes.  Plus it feels good to accomplish something that is not all that easy to do. 

Doing aerobatics in any approved aircraft helps us improve in all these important areas, however, aerobatics in a Stearman adds a bit more dimension.  As many have said before me, a Stearman makes you really learn to fly aerobatics due to its high drag combined with a low horsepower rating.  It’s kind of like watching an elephant dance in the circus.  It can be remarkably graceful or embarrassingly clumsy, depending upon the skill of the “handler”.  

Although I strive to have reasonable skills at aerobatics, I do not claim to know everything there is to know about it.  I leave the heavy lifting to people like John Mohr who is unquestionably knowledgeable, competent, and inspirational to watch in a stock Stearman.  Although is it not my objective to be a top IAC or air show performer, my objective is to use a Stearman for everything it can be.  It seems like a waste not to enjoy what all a Stearman can do if you work with it.  This article is aimed at the person who falls in the middle like me.  So, until you can have a one-on-one with John Mohr, all I can do is share what my experiences have been doing aerobatics and maybe help others learn a little from them.  Of course, when writing an article, it is expected that other readers may likely have had different experiences, results, or ways of doing things.  Those pilots are invited to comment and let us know if they have a better way.

My experiences have been gained three ways:

1. Reading everything I could get my hands on regarding Stearmans and

aerobatics

2. Training from an accomplished air show pilot highly experienced with

     heavy/underpowered biplanes like Stearmans and Wacos,

3.  Practicing over and over and over and over.

I never found the short cut.  Especially important to me was training from someone who knew what he was doing.  I hear pilots say they will just read and go out and teach themselves.  To me, that seemed highly frustrating and even more foolish.  Either way it seemed expensive to keep burning up fuel and time flailing around hoping I’d eventually “get it”.  Instead, several of us asked professional air show pilot, Bill Bruns, to fly with us personally and get us off on the right track.  Good decision!   I still remember his words when I complained to him that my slow rolls were hideous and I couldn’t maintain heading or altitude. “Maybe my stock 220 just can’t do it?”  He took the stick of my Stearman and proceeded to roll it like a chicken on a rotisserie.   He said, “after you do 1,000 of them, you’ll be surprised how much better you will get”.  The moral of the story; get good instruction to reduce your frustration and the chances of damage to you or your airplane, but you will have to practice over and over (in a Stearman) to ever get any good.

Getting yourself ready

Here are some things to consider before just going out and “trying something”.  Although it sounds like common sense, don’t try aerobatics if you are physically or mentally tired.  There will be significant excitement and a degree of stress that closes your situational awareness to begin with.  Being tired makes it overwhelming and pointless. You need everything alert.  It’s a waste of fuel otherwise.   Remember, aerobatics can be exhausting if you aren’t used to them.  After fifteen minutes (or less), quit.  Also, don’t allow an instructor to explain things in the air.  Read about the maneuvers on the ground, discuss them there, and finally try them in the air.  Study and know what to expect before flying.

 Equipment is important.  Parachute properly rigged and signed off is a must.  Don’t forget, if the rigger’s sign off is not current, you are in violation if you wear it.  Spend some time and actually understand how it functions, adjusts and opens. Practice (on the ground) getting out of your seat belts, removing your helmet, and “jumping” out of the plane. Practice jumping off the wing, bringing your ankles together, looking at the D-ring, and then pulling it with both hands.  All this is NOT easy if the airplane is out of control.  On-ground rehearsals and reviews may save your life.

 I like leather gloves because I seem to get a better grip on the controls.  Personal choice.  I always wear sunglasses instead of goggles because I get a wider field of vision, however, I recommend resting goggles on your forehead in case you need them in an emergency like hot oil spraying from a broken oil line.  But have them adjusted tightly or they will get blown back over the top of your helmet and flutter and smack the back of your head.  It looks goofy and very uncool.   I like a reasonably firm rubber sole shoe on the rudder pedals because they feel more positive than a sneaker or lighter weight shoe.  But watch out for the clod-hopper type that are just too big to provide any sensitivity or finesse.

 Do not fly with open cuff shirts, flight suits, or flight jackets.  They can catch on controls, seat belts, etc. as your arms are moving the controls around.  A friend of mine had a Navy cadet use both hands on the stick to recover (much too aggressively) from a stall.  When he pushed forward on the stick, his left jacket sleeve unhooked the seat belt lever and he catapulted himself right out over the center section into the Michigan sky.

 Before flying, sit in the cockpit and move the controls while watching several things. Pull the stick back and watch to see if you are pulling straight.  Inexperienced pilots will pull the stick back by pivoting their right arm at the shoulder instead of the elbow.  The result is to pull the stick back and right which will tend to cause a right roll on the loop entry.  This will pull the airplane off heading upside down and the plane will come out the bottom of the loop heading in a different direction and leave the pilot disoriented.

Look at your arm pull straight back.  Do it 20-30 times to build muscle memory.  It will help avoid one of the first common errors of any maneuver.  A bad start.  More on that later.  Move the stick and rudder pedals to all extremes just to convince yourself you have enough leverage to do it.  It was amazing to me when I was at first upside down how it seemed I couldn’t possibly reach far enough forward to hold up the nose.  Try it on the ground and see how easy it is.  Another common error when rolling upside down is to use the stick as a handle to hold on to so you won’t fall out.  The only problem with that is you will pull OUT on the stick which brings it to the center and the roll stops.  You end up hanging upside down.  Sit on the ground and visually look at the stick and practice bumping it against the stop.  Try that little trick of “bumping” when flying and you may be able to overcome that tendency to pull “OUT” on the stick when you transition through upside down.

 Read & Understand the Math (which many pilots don’t)

Understand about load limits (G’s).  What geometric influence do speeds, weights, and angle of banks have on limits? What’s the difference between a +6G limit load factor  and the approximate 9G ultimate load factor?  What things can happen at 6Gs?  9Gs? Is it ok to exceed 6Gs?  Could you ever pull 6Gs in a Stearman?  How?  9Gs? How?  How fast can you fly a Stearman and make full control deflections without bending anything? Is it 1.73 x 51mph =88mph?  Or is it 2.45 x 51mph = 125mph? How many Gs will cause permanent structural failure?   If a solo pilot weighing 160 pounds is flying at 105 mph with 10 gallons of fuel and zero baggage, will he do any structural damage by pulling the stick all the way back and pressing full rudder?  This is not just theory stuff for an engineer.  I would suggest getting a thorough understanding if you want to really avoid the anxiety whether or not a Stearman will hold together.  Read about load factors in the books Aerobatic Flight Training by Lt.Co. Art Medore and Basic Aerobatics by Szurovy and Goulian.

 Also, read and understand FAR 93.303 and 93.307 regarding the legal requirements for aerobatic operation and the use of parachutes respectively.

Getting your Stearman ready

Stay as light as possible. Try to have no more than ¼ tank of fuel. Use a McCauley prop.  Install double belts.  Make sure the seat belt lever is on the left side NOT the right side. Vacuum out dirt in belly.  Empty the baggage compartment, flight cases, or any other pouches on board.  Remove seat cushions unless they are tied to the seat.  Have an A& P or IA inspect the airplane for things important to safe aerobatics such as:

  • · Seat belt attachments. Secondary belt attached to fuselage frame
  • · Inspect/remove loose objects on bottom of bird cage (pens, tools, bolts, etc.)
  • · Flying wires and terminals.

Test the witness holes on each terminal to assure the threads are in at least this far

  • · Check battery drains and caps do not leak into fuselage, double check hold-downs
  • · Visually inspect prop (esp. McCauley) hub and clamps every time
  • · Install a G-meter.
  • · Know what is inside the wings.  Age and condition of spars?  Condition or corrosion of metal spar plates?
  • · Fabric tested

Learn the Numbers

 

RPMs

Calibrate your airspeed indicator as a tachometer.  First thing, fly your Stearman in level flight and push the throttle wide open.  Record the exact airspeed and rpm once the a/c has stabilized at full throttle.  Second, lower the nose and watch both airspeed and rpm’s increase.  Keep this going until the rpm’s reach redline (e.g. 2075 on W670) and immediately record the airspeed at which this occurs.  Now you have calibrated your airspeed indicator; so as long as you keep your airspeeds under this number, you will not exceed redline rpm, let alone the maximum allowable rpm.

 It is important to understand the difference between redline and max allowable rpm.

Redline is the point of 100% power, which may occasionally be exceeded.  However,  max allowable rpm may not.

 Interestingly, redlines and max allowable rpms vary by  Stearman model and different engine/prop combinations as specified in the respective pilot’s operating handbooks.

The following rpm limits are published in each of the respective pilot handbooks:

         N2S-3                                           PT-17                                                 N2S-5/PT-13D

     W670 Cont                                 W670 Cont.                                                W680 Lyc.

                                         (Wood Prop)                 (Metal Prop)              (Wood or Metal Prop)

 Redline RPM                  2075 RPM                     2075 RPM                           2100 RPM

100% Power

 Maximum

Allowable                        2280 RPM                       2490 RPM                          2520 RPM

   RPM

 Regardless of these really high max allowable rpms, I try to stay at least 50 rpm below redline.  However, depending on prop pitch settings, rpm’s can easily get away from you, so be very aware of this!  More about the important effects of different prop types and pitch settings will be covered later.

 Airspeeds

Next, write down entry airspeeds for the basic maneuvers and attach them to the instrument panel for easy reference until you work out your favorite speeds for your airplane.  The following airspeeds have been published by different sources. 

                              Aerobatic Flight              Wayne Pierce              US Army                        US Navy   

                              Training Book

Loop                            120                          Dive to max rated             125-30                              127

Immelman                 130                             120% Top Crs                    145                                 143

Barrel Roll                  110                                120 mph

Slow Roll                     110                               Vc to FT                            115                                 110

Split S                         70***                             Vc to FT                          80***

Hammerhead             120                                130% Vc

Cloverleaf   –                                                    140 mph

Cuban 8                       125                                    **

Reverse Cuban 8   –

 *** Entry described only from snap roll

 When discussing these maneuvers in detail, I will comment on which speeds seem to work best for me in a stock 220 Continental with a McCauley prop., and the pitch settings for the prop.

 The next article for the Feb 2003 Issue, will focus on warm up maneuvers and procedures for making consistent entries to rolls and loops.  Without consistent and accurate entries, the rest of the maneuver is jeopardized.  Specifically, we will discuss the key to a straight loop. How to roll without dishing out. And how to “get vertical”.