Will Fox's Altitude Record Holding Pegazair 100


Pegazair P-100  High Altitude Flight
Flight Summary
Date : 12/19/07
Pilot: Will Fox
Aircraft: Pegazair P-100 with a turbocharged Rotax 914 UL engine
Altitude achieved: 26,100 ft
Outside air temperature @26,100 ft: -33 F
Time to climb (7150'-26100'):  37 minutes
Duration of flight: 57 minutes
Description of flight:
I was getting ready to take off from the Los Alamos airport to climb  to 25,000 ft to test the performance of my Pegazair P-100 and my glasses kept fogging up.  It was below freezing outside and my oxygen mask leaked when I exhaled, and the water vapor was condensing on
the right lens of my glasses.  I kept wiping it off as I went through my run-up checklist.  The anti-fog that I put on my glasses just  wasn't working. 

The same thing had happened the day before on my test flight.  I had been attempting to see how high my Pegazair would fly for several months now. I had made two previous flights during the summer and fall to see how the turbocharged Rotax powered aircraft would perform.

On the first flight, I had oxygen, but I stopped at 17,500 feet because I didn't have the IFR clearance that is required above 18,000.  On the second flight I had oxygen and an IFR clearance but  stopped at 21,000 feet when it became apparent that the above standard
outside air temperatures were really effecting performance and as a  result I wasn't going to be able to go too much higher. But what really happened, was that I also lost my nerve as I began thinking  about all the things that could go wrong with the engine and the plane. The  malfunction ghosts come to haunt you when the timbre of the engine changes or a strange vibration rumbles through the airframe. They seem to make their presence known whenever you are unsure of yourself or your aircraft. That flight showed me that to beat them, I needed to think through failure scenarios and emergency procedures more thoroughly and have a plan to deal with them. It also demonstrated that the aircraft was capable of flying higher if I could do it on a day with lower temperatures at altitude.

Breathing Oxygen

I thought I was finally ready to try it again. I planned to attempt a climb to Flight Level 250 a couple of days ago, but it ended up not happening because of responsibilities associated with my day-job. Yesterday, at noon I got the aircraft ready for the flight and did a test flight to 15,000 ft MSL to make sure all systems were OK.

That's when I found out that he oxygen mask did not fit the bridge of my nose well and the right side of my glasses kept fogging up.  This had not been a problem in the warmer summer and fall months, but with outside  temperatures a few degrees below freezing at the surface, it was making itself quite apparent.  I would try using an anti-fog on my glasses since modifying the bridge of my nose or the oxygen mask to match was not likely to happen before tomorrow.  A little water mixed with dishwashing liquid should make a fine anti fog agent.

Well, so much for that great idea. As I had finished my run-up checklist and set the altimeter to match the airport elevation of 7,180 ft, my lens fogged up again. I wiped it off again and dialed in ABQ Center's frequency to pick up a clearance.  I had earlier filed an IFR flight plan from Los Alamos to Los Alamos, direct, with a request for an unrestricted climb to 25,000 ft for an aircraft performance test. I called center to pick up the clearance and it was clear that the cryptic flight plan was a bit confusing.  As the controller began reading back the clearance, he paused and asked me exactly what I wanted to do. I told him I wanted to stay in the local Los Alamos area and climb to 25,000 ft for a performance test.  He asked me if I was ready to depart and I said that I was, so he said he would give me a squawk once I was airborne and he would work things out then.That worked for me. I called Los Alamos traffic, informed  them of my intentions, wiped my eyeglass lens one more time, back taxied runway 9, and took off.

I turned north after departure and trimmed the Pegazair to an IAS of 55 mph, reduced the manifold pressure from 38" to 34" and the rpm from 5760 to 5500. I was climbing at over 1100 fpm and the EGTs looked great. They were all within 50 F of each other. As I climbed through
10,000 ft, I switched over to ABQ center's frequency and after a moment called them with my N-number, location and altitude. The controller came back immediately with a squawk and a question as to my anticipated climb rate. I told him that I should be able to average 500 fpm.  He cleared me to 19,000 ft initially, and to expect 22,000 ft in a few minutes.

Los Alamos at the Eastern Edge of the Jemez Mtns

As I climbed through 15, 000 ft, I began to think about what could go wrong. My biggest worry was that red-hot turbocharger and exhaust system under the cowl. There is a whole lot of heat under that engine cowl that can wreak havoc on metal and rubber components that are not
well protected.  I had seen broken exhaust brackets, leaking exhaust expansion joints, cooked oil lines that cracked, and baked sparkplug leads that simply fell off of the spark plug, during the 500 hours that I had accumulated on the engine. I had thoroughly pre-flighted the engine prior to this flight but what if I missed something? Suppose an unknown section of oil line had become brittle and begun to drip oil on the hot exhaust system? A fire would soon develop, that I had no way to combat. My first indication of a problem would be the smell of smoke in the cabin. Then it would be a race against time back to the earth's surface, to get on the ground before the engine mount failed, the engine separated from the airframe, and the aircraft became uncontrollable, or worse, the fire burned through the firewall and burned me alive.  Even my Ballistic Recovery System couldn't save me from an in-flight fire. My only hope was to get back to the safety of terra firma and away from the airplane. At my maximum descent rate it would take at least 6 minutes to descend from 25000 ft back down the airport.That might be just a little too long. A friend of mine died, when he crashed because of an engine fire shortly after takeoff.

Sandia Mountains to the South


Valle Grande and the Ski Hill

Wheeler Peak and the Colorado Mountains behind.

It didn't help that his engine was a Rotax 914 just like mine. The ghost of engine fires sent a shiver down my spine.

I climbed through 16,000 ft and pushed the throttle and propeller controls all the way forward to maximized engine power.  My manifold pressure would slowly drop from here on up because the waste gate was completely closed and the turbocharger could no longer keep up with the decreasing air density.  It would be interesting to see what my manifold pressure would be when the Pegazair stopped climbing.

Colorado in the distance

Center called and cleared me to 22,000 ft and asked me for clarification on type aircraft.  I told them my designation was PEGZ and that I was a  two place STOL aircraft. I think they were getting curious about what kind of experimental aircraft they were tracking. I was flying an
oblong orbit during my climb and I noticed that the Garmin GPS showed a ground speed of about 40 knots on the upwind leg and 100 knots downwind leg. I climbed through 19,000 ft.

 I only had 6,000 ft to go. I almost forgot to change my barometer setting to 29.92. I'm not used to flying above 18,000 ft.  I checked my Pulse Oximeter. My oxygen saturation was at 98% and my pulse rate was 106 beats/min. That was almost twice my rest pulse of 58 beats/min when I was sitting in the car earlier in the morning checking out the pulse oximeter. My saturation level had  been 96% at that time. It looked like I was getting plenty of oxygen.

I had decided ahead of time that if my saturation level fell below 90% I would abort the flight and begin a descent. It was getting cold up there.The outside temperature was -5 F and I started to think about the possibility of ice forming in the fuel lines. It would be -30 F or more at 25,000 ft and any water in my fuel system would be a solid chunk of ice.  I had thoroughly and frequently sumped the tanks and fuel lines during the preflight. There were 5 sump locations and I checked them all. I should be fine. Even if with a plugged fuel line and a dead engine, I could easily glide back to the airport and make a dead stick landing. That is a nice thing about the Pegazair, it has a decent L/D as well as exceptional vertical and horizontal speed ranges that make spot landings a lead pipe cinch. I checked my pulse rate again and it was 112 beats/min.  Oh, those damn ghosts were at it again.

I climbed through 21,000 ft and thought, that at least I beat my previous record.  I looked at the cirrus clouds above me and began to look for holes to climb through if necessary.  I had been   experimenting with my climb rate and now it seemed that 50 mph gave me the best performance.  My manifold pressure was dropping more rapidly now. It was down to less than 30".  As I climbed through 24,000 ft I wondered about getting hypoxia or decompression sickness. I checked my oxygen saturation again. It was down to 96%, but still well above  the 90% abort point.  I had started breathing pure oxygen on the ground about 15 minutes before the flight to reduce the nitrogen in my body. I didn't want to get the bends. I had meant to start
breathing  oxygen 30 minutes before the flight and I wondered if it made much  difference.  I felt ok and wasn't experiencing any numbness or soreness in my joints. I didn't have any earaches, toothaches or sinus headaches. I could still multiply 7 X 8 and get 56 so the old   noggin was still working pretty well. Sometimes I had a hard time remembering that particular multiplication even on the ground. The ghosts were just teasing me.

Altitude and Airspeed

I hit 25,000 ft with a sense of elation. I had done it. What a great little plane. I leveled out and accelerated to 80 mph indicated.  I  rubbed the ice off my right lens and noticed that the view was incredible.  It wasn't the same as looking out a tiny window on a passenger jet.  The Pegazair afforded a lot more window to look out  of. I could see a 100 miles to the north, east and south.  There were clouds coming in from the west over the mountains.  The mountains were snowcapped and the sky was crystal clear with scattered cirrus clouds a few thousand feet above me.  I made a slow 360-degree turn and just took in the moment. The speed difference between my climb and cruise speeds seemed to indicate that the Pegazair might just go a little
higher.  I thought for a moment and then called Center and let them know that I was level at 25,000 ft and requested 26,000 ft. They came  right back and approved 26,000 ft.  The climb to 26,000 ft seemed to take a long time. The climb rate hovered just above 100 ft/min.  I  leveled off at 26,100 ft and the plane accelerated to 65 mph indicated. This was really cool. I had not only climbed to my goal of 25,000 ft but had exceeded it by more than 1000 ft.  I enjoyed the feeling of being as high as I have ever been in an unpressurized aircraft and in one of my own making to boot.  After a few moments, I called Center to let them know that I was ready to go back down.

They cleared me back down to 14,000 ft.  I kept the rpm up to keep the engine warm, and reduced the manifold pressure from 20.5" down to 16" as I pitched over to an indicated airspeed of 110 mph.  This turns out to be around 170 mph TAS at 25,000 ft. The airplane felt solid as a  rock and I gingerly pulsed the controls in all three axis to check for any control oddities that might appear at this high TAS. Everything felt fine, no unusual vibration, sensitivity, or strange pressures on the controls were apparent.The ghosts were finally gone.

Slats out at FL270

I wanted to prevent shock cooling the engine, so I kept the rpms at   5760 and the manifold pressure at 16" as I descended several thousand feet.  At 19,000 ft, center asked me if I could increase my descent  rate to avoid a conflict with IFR traffic climbing through 17,500 ft  that was coming out of Santa Fe.  The engine was nice and cool now, so I reduced manifold pressure to 12" and pitched over to 120 mph indicated and my descent rate went to 1700 ft/min.  After the traffic was clear, I slowed back down to 100 mph indicated and as I
approached 14,000 ft, I cancelled IFR. I thanked Center for the help and the controller said that he was happy to oblige.  I set up for an extended right downwind for runway 27 at Los Alamos and pulled the annoying oxygen mask off and cleaned my lens off one last time.  On final approach, I wiggled the rudders to wake up my feet for the landing. I made an unusually nice wheel landing, even if I do say so myself. I taxied up to the hanger and shut down.

 As I sat there, and though about the flight, I wondered why I felt so good.  Lots of people have climbed a lot higher than I did. Thousands of passengers on commercial and business jets do it every day.  I guess the difference is that they don't do it in an airplane that they  have built with their own two hands. They also don't get to pilot the exploration flight that probes an aircrafts flight envelope for the first time.  I guess this combination of airplane builder and test pilot is what feels so good.  It is a gratifying experience and a significant achievement to build and then test fly your own airplane. 

We are lucky in this great Country to be able to build experimental aircraft of every sort and to be able to go test fly them ourselves in the national airspace.  It says a great deal about the freedoms we Americans enjoy, and about organizations like the EAA and AOPA that work exceptionally hard to maintain these freedoms for all of us. 

Everyone that builds and flies their own plane has the chance to experience this feeling. Whether it is that first flight after construction is complete, or the Phase I flight envelope exploration, or additional test flights later in time, we get a chance at that feeling. It's a great feeling.  It's something to write home about.

Flight Parameters at FL270


On January 1, 2008 I climbed into the Pegzair for one last trip to the Flight Levels before I put a different engine in it. I wanted to see if I could get a little higher than the last time I was out and take a few pictures while I was there. This time I was able to climb to FL270. The Pegazair was still climbing at a little over 150 ft/min, but I was running out of oxygen and Iím sure Center was running out of patience, so I called it quits. Iíll bet the Pegazair still had another 1000 ft of climb left in it.


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