12December2017

You are here: Home Articles Others Objective: Overcome 78 turns of inverted flat spin
Monday, 21 November 2011 11:08

Objective: Overcome 78 turns of inverted flat spin

Written by  Snap&Roll
Rate this item
(0 votes)

Spencer Suderman

78 turns of inverted flat spin was the new Guinness Record attempt to beat, tried by the American airshow pilot Spencer Suderman with his Pitts fully prepared and equipped for the occasion. With Drift HD170 cameras on board to record the attempt, two judges FAI to give autenticity and an oxygen system for the pilot, the attempt was initiated at an altitude of 21,000 feet from inverted flight during the Air Festival Center (San Diego).

Spencer Suderman explains in exclusivity in Snap&Roll the conclusions from his experience after trying to beat a world record since 1999 nobody had tried to beat.

If you are a pilot the following paragraphs should leave pulled muscles in your brain trying to wrap your mind around the numerous questions that the situation I describe brings up.  

The current inverted flat spin world record is 78 turns from an altitude of 16,000’ and has been held by Wayne Handley since 1999 when he broke his own previous record of 67 turns from an altitude of 12,000’ in his Pitts S1 set ten years prior.  Wayne said that he did it for the publicity[1] and frankly, I pursued this record for the same reason.

Ever since I started performing aerobatics I have been captivated by the inverted flat spin but it wasn’t until I became an air show pilot in 2006 that I thought of going after the record.   My opening maneuver in every air show is the spin albeit a short one of about 10-15 turns started from a relatively low altitude.  After procrastinating for years I decided in the beginning of 2010 that 2011 was the year I would finally do it.

Las vueltas de barrena vistas desde el sueloA las 10:15 am del jueves 10 de marzo 2011 despegue del Servicio Aeronaval (NAF) El Centro con mi avión Biplano Pitts S-2B Meteor hacia el norte, en dirección hacia el Área Restringida oeste2510A  subiendo a 15.000 pies ('altura límite de la zona restringida”) y me dirigí al espacio aéreo clase A  habiendo sido autorizado inicialmente a nivel de vuelo 250 (25,000pies), y posteriormente a nivel de vuelo 270. Colacionando la autorización del ATC le dije: "El Centro, Pitts 260gr autorizado a ascender a nivel de vuelo 270 y con esperanza a poder llegar hasta allí arriba" cuando en ese momento un avión de Southwest Airlines se le oyó decir por la radio: "Una Pitts aquí arriba????, en que demonios está pensando este chico! "

At 10:15 AM on Thursday March 10th 2011 I took off from Naval Air Facility (NAF) El Centro in the Meteor Pitts S-2B Biplane headed North West bound into Restricted Area 2510A then climbed through the 15,000’ ceiling of the restricted area and headed for class A airspace having been cleared initially to FL250 then subsequently up to FL270.  While repeating the clearance to ATC I said; “LA Center, Pitts 260GR is cleared to flight level 270 and hoping to actually make it that high” at which point a Southwest Airlines jet was heard to say, “A Pitts up here, what the hell is that guy thinking!”

At 10:44 AM I reached 21,000’ and that was as high as the plane would climb so I rolled over and initiated the inverted flat spin. 

After spinning through 18,000’ in 3 minutes I started the recovery at 3,000’ ending the maneuver with a gentle pull to level off at 1800’ and called El Centro tower to request a landing clearance.  After issuing the clearance to land the tower congratulated me on a new world record having heard from someone in the crowd on the ground in the restricted area that I did 93 turns.  I had no idea how many turns I actually did because its impossible to count them for that long of a spin while paying attention to so many other things related to managing the aircraft systems as it descends at 6,000’ feet per minute while trying to maintain the requisite level of situational awareness to recover the maneuver safely.  In the end the onboard cameras clearly showed that I was only able to complete 64 turns and not set a new world record.

Not the least of the questions you may ask  is:  How does a civilian aircraft  - certified only for day VFR flight - depart from a military airport,  fly through a restricted area into class A airspace and perform an aerobatic maneuver that is widely misunderstood, probably never been done to this extreme and definitely never been documented in this detail?

Describing the inverted flat spin is actually a challenge because it is not really a spin at all but a gyroscopic maneuver driven by the precession of the turning propeller.  An upright or inverted spin is an aggravated stall where one wing produces more lift than the other, resulting in autorotation[1] but the airplane is still flying since the lift is reduced not eliminated[2].  The inverted flat spin is an evolution of the inverted spin since power is added to the inverted spin when right rudder is used in planes equipped with Lycoming engines turning clockwise as viewed from the cockpit.  As the power is added the nose rises toward the horizon and the plane turns around its vertical (yaw) axis like a top placing the wings almost perpendicular to the airflow as the plane falls towards the ground.  The plane is definitely not flying, only falling and the flight controls are virtually useless until the power is reduced and the plane returns to an inverted spin where it can be recovered.

Spencer Suderman intentado batir el record

In preparing for my record attempt I sought advice from many skilled pilots including Wayne Handley and quickly learned that very few really understood the maneuver well enough to provide salient advice and I would have to figure much out for myself.  At that point all I knew is an oxygen system would be required due to the altitudes involved so I contact the usual vendors and finally selected a system from Aerox that included a full face mask that could attach to my flight helmet and a small cylinder that could be strapped into the front seat of my Pitts and provide 60 minutes of Oxygen up to 25,000’.

 

The Pitts biplane is highly capable of entering and recovering from spins and with its io-540 engine and 3 blade propeller has plenty of climb performance but I have never had a reason to climb much above 12,000’.  The first thing I had to figure out is how high could it go because I wanted every bit of altitude I could muster for the actual world record flight.  According to published data the service ceiling is 21,000’[1] but of course its not IFR certified so legally I could only fly up to but not over the floor of class A at 18,000’.  No one I talked to ever flown a Pitts that high so there was no knowledge of how high it would really go but since service ceiling is the altitude at which the aircraft is unable to climb at a rate greater than 100 feet per minute[2] I figured I could eek out a bit more than 21,000’ from the plane but that would later prove untrue :(.

 

Repasando los videos con los jueces

The first test of my new oxygen system was a flight to the floor of class A airspace to determine time to climb and fuel burn.  This was the first of many educational flights all recorded on 2 or 3 HD video cameras on my helmet and inside the cockpit where I incrementally expanded my knowledge of the Meteor Pitts.  The lesson of the day was 19 minutes to climb to 18,000’ burning 8 gallons of gas.  The plane still had plenty of climb left so I was highly encouraged.

By the middle of 2010 I had the equipment needed (airplane, oxygen, video cameras) so my attention turned to finding a place to perform the actual record breaking flight while gaining maximum exposure for my effort and of course lots of practice flights to increase my stamina in the spin while testing spin performance from different altitudes.

Since I was already scheduled to perform in the 2011 NAF El Centro Airshow as I have done in prior years I approached my contacts there about doing this world record attempt as part of the show.  Since 2011 is the Centennial of Naval Aviation Celebration at all Navy air shows it would be an added value to have a world record set at the same show that kicks off the Blue Angels season.  Plus I figured that since they own the airspace they could clear me to the altitude I would need, if only it were that simple… 2 days later I had a call back with an enthusiastic thumbs up but with the caveat that I had to deal with any regulatory issues that might come into play which meant my next call was to the San Diego FSDO.

I have always maintained great relationships with the FAA employees that I have encountered at the air shows where I have flown so I called the inspector at the San Diego FSDO who usually oversees the El Centro air show and told him what I wanted to do.  He told me to give him a few days to run this down then he would get back to me with some operational guidelines.  A week later I got the callback and was both disappointed and encouraged at the same time.  I would not be allowed to perform this attempt at the air show in waivered airspace for a number of reasons but mainly because of a rule that you must have practiced your performance within 15 days of the air show and since I would not be able to practice the spin from altitude before the attempt I wouldn’t meet the requirements. The FAA, however, did suggest using the restricted area adjacent to the El Centro class D, and since it is controlled by El Centro they could authorize it.  There was hope!

While El Centro was onboard with this plan the restricted area 2510A only goes up to 15,000’ so I would need a way to get above 18,000’.  Once again my friends at the FAA had thought this through and suggested that I apply for an altitude reservation (ALTRV) which would allow ATC to clear me into class A and protect the airspace around me in a predefined circle up to a specified altitude.  The only requirements for my aircraft are a VHF radio and a mode C transponder, CHECK!

While it still took several months to get the ALTRV approved and no less than a dozen FAA people on an ever growing CC list in the emails to review it, in the end they were nothing short of supportive and encouraging for my requested activity.

When I registered my attempt with the Guinness Book of World Records website they sent me a requirements document which stated that two IAC judges had to witness,  adjudicate the attempt and fill in affidavits in order for the record to be accepted.  I contacted Jim Nahom and Casey Erickson who enthusiastically agreed to do this although both questioned my sanity (they weren’t the only ones).

Dentro la cabina durante la barrena

I am not sure if it was a coincidence or collusion but a few days later they each called to review in detail with me what I had asked them to witness.  Casey not only runs a flight school but competes in her Pitts S1 and Jim had competed for many years in a Pitts S1 as well.  They are both extremely familiar with how a Pitts flies and its capabilities and did some math to figure out that if I was going to get 79+ turns in the spin given that a Pitts can only do ~5 turns per 1000’ below 7,000’ and less as the altitude increases then I would need to climb to 24,000’ to do this.  I told them that their estimates concurred with the practice flights I had been doing with video and the data I was gathering by spinning in 5,000’ blocks of airspace from 3k-8k, 5k-10k, 8k-13k, 10k-15k, 13k-18k and tracking on a spreadsheet then extrapolating the performance up to 25k.

During these flights I was trying to figure out ways to make the plane spin faster.  I tried various stick positions and just letting go, which sends the stick to the left forward corner and the plane oscillates a bit but the spin rate remains unchanged.  I tried different engine RPM’s and power settings but at altitude the manifold pressure is low anyway so that didn’t matter but RPM had a noticeable impact on spin rate, although small.  I reduced RPM’s in the spin until the nose dropped a bit then added 100 RPM back in and got about a ½ turn per 1000’ higher spin rate than at 2700 RPM.  Keep in mind that a 64 pound prop can exert a lot of gyroscopic precession but also a fair amount of rigidity.

After studying the videos and building data models I concluded that once the spin is developed the stick position has no impact but keeping it forward and slightly to the right would keep the plane from doing uncomfortable oscillations and not overstress my arms from holding the stick against the pressure of the flight controls for several minutes.

The flight on March 10th was the culmination of years of desire and emotional investment with a liberal helping of practice/conditioning flights and a very steep learning curve on all aspects of the flight including mechanical, physics/gyroscopic, physiological, regulatory, and promotional.  So many people and organizations supported me in this effort and that list includes the NAVY and FAA, numerous product manufacturers who provided Cameras and Oxygen equipment, my Air show Competency Evaluator (ACE) Bill Cornick and of course my wife Stacey and family 

Here are my lessons learned; 

  • The descent rate of a spinning airplane is not linear so the higher you go the faster it falls and that makes sense when you consider the decrease in ambient pressure as altitude increases.  My spreadsheet was wrong, VERY wrong L
  • The rotation rate of the airplane is consistent at any altitude and the inverted flat spin is purely a gyroscopic maneuver that cannot be affected by the ailerons or elevator and cannot be accelerated like a regular upright or inverted spin.
  • Going higher is not the solution and never will be; spinning faster is.

 The questions I get asked:

Why has no else tried this since Wayne in 1999 and before you in 2011?

I don’t know because it is really not hard to do this you just need to climb high then hold right rudder and hold the stick forward and to the right and wait.  I think you could train a monkey to do it.

What if you turbo-charge the plane or use Nitrous to get more power to start higher?

That won’t work.  Even if I could have reached 25,000’ that might have only gotten me another 8 turns, I think, and still wouldn’t come close to the 79 needed to break the record.

Will you do this again?

Yes if I find an airplane that can climb to 20,000’, spins faster and can stay inverted long enough without fuel/oil starvation.  I have looked at all of the common aerobatic planes and talked to the manufacturers and it seems that no one makes a plane that can do all of these or someone would have done it by now.

 

 
Read 3022 times Last modified on Wednesday, 20 November 2013 08:39
More in this category: Know Your Parachute »
Login to post comments
"Aerobatics is the hidden rythm of our soul..."

Newsletter