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I learned to fly in Victoria, Australia in the 1960s while I studying Aeronautical Engineering at RMIT in Melbourne, specializing in Aerodynamics. I trained on Victa Airtourers at Moorabbin Airport with Civil Flying Services. The CFI was Jock Garden a highly respected WW2 pilot, senior instructor with UK Central Flying School, and a test pilot on early jets. The Airtourer was designed by Henry Millicer, one of my lecturers at RMIT and was built by the Victa Lawn Mower company in Bankstown, NSW. Henry and I were of Polish extraction and we got along well.
Next to Civil was Schutt Flying School with two Mooney M20s on the flight line. I had always been “besotted” by the Mooney as I felt the design was well ahead of the norm – it looked like it was doing 200 kts. while sitting on the ground. I studied up on its aerodynamic design and performance characteristics as a precursor to getting an endorsement. Coming off basic trainers, I figured that the M20 would be an exciting challenge.
Schutt Flying School had two Mooney M20s on the flight line.
The briefing was by an instructor, who was about my age, before we proceeded to the aircraft. After a pre-flight check, we climbed on board and taxied out. Flight control checks were good and we got our clearance. The M20 accelerated down the runway and I had been told to look for 60-70 kts. for a smooth takeoff and climb out. The Mooney lifted off (virtually by itself) and I could feel the acceleration. Glancing at the airspeed indicator (ASI), I was surprised to see only about 35 – 40 kts. The M20 was good, but surely not that good. We continued to accelerate and had become definitely airborne but the ASI still showed around 40 kts. Something was not right with the ASI – we were flying!!
As the remaining runway was being consumed at an alarming rate, and given that a high performance aircraft like the Mooney preferred to be airborne, I reached for the landing gear retract handle ready to “clean her up” as I fully intended to continue the takeoff and circle back to land with or without an operational ASI. As pilot-in-command, the instructor took over. Power-off , stick forward. Much like a flat stone skipping across a pond toward the opposite embankment, we proceeded down the runway. To his credit, the instructor eventually managed to land on the runway, pulling up on the grass verge. Expecting the worst, we were surprised to see that the Mooney appeared intact with no visible debris on the runway; however, the prop tips were bent back almost 90 degrees due to impact with the runway.
Many aircraft have upturned wing tips (winglets) to improve aerodynamic efficiency and reduce wing span. Similarly, some prop blades had bent back tips to improve aerodynamic efficiency and provide better ground clearance. These were known as Q-tips, normally done in a Jig not on a rotating engine in close proximity to the ground. This Mooney would not be flying for some time as no doubt the engine must have been damaged. I did end up getting my endorsement on the other M20 on the same afternoon.
What had transpired?
First, the M20 had an aerodynamically operated flap cover over the pitot tube rather than a pitot sock and flag. At some stage, a wasp got past the flap, entered the tube, built a nest, and laid some eggs partially blocking the pitot tube causing the ASI to malfunction.
Second, the Mooney had an efficient laminar flow wing. These are pre-disposed to a phenomenon called an aerodynamic drag bucket. In simple terms, at low angles of attack and particular lift coefficients, the drag coefficient of the wing drops, sometimes deeply and abruptly, while the lift coefficient stays up. The lift to drag ratio can increase markedly as you enter the drag bucket and drop as you exit. Also, laminar boundary layers are generally sensitive to local airflow conditions and can easily “trip” into turbulence or high drag. I believe these two aerodynamic phenomena in combination and along with the abort event, had caused our “pirouette” along the runway. Because I had never experienced this combination, I chose to continue the takeoff.
The Mooney had an efficient laminar flow wing pre-disposed to a phenomenon called an aerodynamic drag bucket.
Another factor supporting my decision was something that I experienced during my training. My CFI had a surprise for me one day. When I got into the Victa, I saw that he had covered the ASI. This was not in the syllabus. Jock did help me through the initial circuits but after that, it felt natural. I never really understood or appreciated the rationale behind this exercise but his words made some sense: “Man has always wanted to fly like a bird, so, when you fly, think and act like one, don’t you be flown”. Maybe he wanted me to develop an “inbuilt instinct” about flying. “You never know when”.
Lessons learned
It is almost guaranteed that the unexpected will happen quite suddenly and at the most inopportune moment and usually with little time to react. What you do determines the outcome. Classic advice is: stay alert, calm, think logically and resist panic. Panic clouds judgement and reactions, usually resulting in a bad outcome. I also think that knowing the vagaries of your aircraft helps.
Rightly or wrongly (to the casual observer), I believe, given my knowledge of the aerodynamics pertaining to this type of aircraft and prior experience during my training, I could have saved the Mooney from any damage on that day. At no stage had I considered that continuing the takeoff would be worse than aborting. I had every confidence I could fly the aircraft, as it was already airborne and aerodynamically stable.
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I agree, for VFR in your situation flying the airplane without an ASI would be the option I would choose to make a circuit and return to troubleshoot the problem.
I owned and flew an M20 Mooney for over ten years. You wanting to keep her airborne was the right call. The decision to chop power with diminishing runway on an airplane that is showing positive flight and climbing characteristics was a panic reaction. Fortunately, both of you walked away and only damaged the prop and engine. Mooney, a fantastic flying machine in every category, prefers to be in the air over on the ground. Slowing it down to land is more of a challenge than other singles, but that is a plus, not a minus. If I can find a place to park one, another Mooney, newer and with a glass cockpit, is on my bucket list.
I would have continued the take off as well, seems dumb to me to abort a takeoff without enough runway to safely land and stop just because of an ASI not working. You should be able to safely fly VFR without an ASI if you have to, beside you can always use your GPS ground speed as a guide to airspeed if it’s not to windy
You were VFR
Pitch and power indicated the Airplane was flying you’re lucky it wasn’t worse
My first instructor required me to fly the entire pattern with the ASI covered before he would sign me off to solo.
Years later, I was flying a 172 when I had a takeoff experience similar to the author’s. It took a few seconds to confirm that the aircraft was climbing normally with normal engine indications. Continuing in a closed-traffic pattern to a normal landing was a non-event. I’m not certain that rejecting the takeoff after becoming airborne would have had as happy an ending.
I had a similar incident in our Cessna 180 when, in the departure turn out I noticed the airspeed indicator acting very oddly. I handed the plane over to my wife, a non-pilot but a pretty good stick, while I troubleshot the problem. Turns out that, after engine shutdown, I always hung the key ring on the alternate static knob and, over time, the knob had been pulled out slightly affecting the static system. Pushing the knob back in cleared the problem and we continued our flight.
Nowadays, after shutdown, I keep the key in my hand and, after climbing down out of the aircraft, I place it on the seat. The plane is kept in a hangar so it’s not a security issue.
Oddly enough I had a similar experience checking out in a Mooney. This was an older aircraft with the aerodynamic pitot cover, and later I discovered that there was just enough friction in the device that it stuck in the closed position. Never having seen such a device before I didn’t catch it on preflight, I flicked it open and it seemed free to move so I continued. There was a difference in my flight: I only had 2500 feet of runway. So, when I didn’t see the “airspeed alive” at about midpoint on the takeoff roll I should have aborted but the plane became airborne right away. I saw the airspeed still reading zero but the aircraft climbed normally. I told the instructor to take over because I’d never flown without an airspeed indicator (first flight in make and model, too) and didn’t understand what happened. He took us around the pattern and landed, being used to the airplane enough that he could judge by manifold pressure and airflow sound when to deploy flaps and gear. I was prejudiced against that aerodynamic pitot cover ever after and never flew an airplane equipped with it.
I hope the instructor paid for the engine overhaul and new prop!
This Monday morning quarterback also believes that flying the airplane with an inop ASI would have been the better option. I was getting my tailwheel endorsement in a Citabria a few years ago and on one very cold morning right after take off our ASI went from working normally to stuck at about 50 knots. A small amount of water in the pitot system had frozen, expanded, and blocked the ram air. I alerted my instructor in the back seat and he simply said to fly the airplane. We alerted tower, were cleared to stay in the pattern, and made a normal landing. It was a great lesson in ‘feeling’ airspeed based on feedback from the airplane.