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Hornet driver: Pushing the limits
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A Canadian Forces CF-18 Hornet fighter Aircraft flies over the coast of Halifax. (CF Photo by Corporal Peter Reed)
First flown in 1978, the venerable McDonnell Douglas (now Boeing) F/A-18 Hornet has served not only with the United States Navy and Marine Corps, but with the air forces of a host of allied nations including Canada and Australia.
While known for its remarkable versatility and outstanding maneuverability, especially at low speeds, the Hornet is not particularly renowned as an exceptionally fast fighter aircraft. On the contrary, “The Hornet is not a really fast jet, but it will go just barely supersonic without afterburner in a clean configuration, something older fighters wouldn't readily do”, said ‘Alf’, a retired Canadian Forces CF-18 pilot. He added, “If you were to ask me how many times I've been over Mach 1, I couldn't tell you. In about 1200 hours on the CF-18 and 300 hours on the CF-5, it must have been hundreds of times”.
‘Alf’ continues, “In air-to-air training at medium to high altitudes, Hornet pilots will often go supersonic, sometimes four to six times during a 1.3 hour mission. Not for long periods, but when it counts- either giving your own missiles a high, fast push for launch, or running away from incoming missiles in a high-speed dive”.
The Canadian Forces CF-18 demonstration aircraft practices his performance over 19 Wing Comox, British Columbia, Canada.(CF photo by Master Corporal Robert Bottrill)
Another time speed can become important is during low-level strike missions. ‘Alf’ explains, “When I was flying the CF-18 Hornet, at least 50 per cent of my missions were extreme low level air-to-ground attack practice sorties over Central Europe. During the late 80s and early 90s, we had decided that the best tactics for the threat at the time involved very high speeds- around 480 to 510 knots- and low level, legally 100 feet AGL in peace time, but lower during war time. The reasons were many, but had mainly to do with surprise and avoiding detection or engagement by surface-to-air threats.
“I have also flown many missions during Red Flag, and Maple Flag, and around the Cold Lake and Bagotville low flying areas, where I spent almost 50 per cent of my flight time at between 250 and 100 feet AGL, and many times saw 600 plus knots indicated airspeed (over 621 miles per hour)”. At low level, 600 knots is about 93 per cent of the speed of sound. To give an indication of just how fast the speed of sound is, ‘Alf” explained: “Typically, Mach 1 is about 720 miles per hour at sea level, and can be as low as 600 miles per hour in the 30,000 to 40,000 foot range”.
CF-18 Hornet aircraft during an Air to Air refueling exercise. (CF Photo by Private Laura Brophy)
While flying fast at low altitude was exhilarating, ‘Alf’ explained that his most memorable feat occurred at high altitude where he coaxed his CF-18 to an astonishing Mach 1.86. As ‘Alf’ explains, “It definitely wasn't easy to get there. I had to push the limits of the rules to achieve that speed; here is how I did it.
“I studied the AOIs (Aircraft Operating Instructions) to see the max speed limits. I found them to be about 735 Knots Indicated Airspeed, or Mach 2.0, as long as the jet was above roughly 33,000 feet- the exact altitude is getting hazy now. It was a maintenance test flight with a clean aircraft and fuel load of about three-fourths full or so.
“I climbed on a Rutkowski path to somewhere in excess of 48,000 feet. Without a pressure suit, it’s not wise to exceed 48,000 feet by much; a pressurization failure can be quite catastrophic. I attained 1.4 Mach in level flight in full afterburner, of course. Then I gently dropped the nose to accelerate at 0.1 to 0.2 G (i.e. describing a gentle descending arc through the sky) while being careful not to hit exactly 0 G - the engines can flame out in prolonged flight at exactly 0 G.
“As I passed through something like 40,000 feet, the nose had dropped to about 25 to 30 degrees down, the airspeed was approximately 705 Knots Indicated Air Speed- I can't remember exactly, because I haven't viewed the 3/4 inch tape in years- and the Mach was building past 1.84. At that point the nose started to snake slightly (wandering back and forth slowly) and I got scared! I pulled the nose up gently, while retarding the engines to minimum afterburner. I saw 1.86 on the Mach in the HUD, and then it started decreasing. The nose stopped snaking.
“I pulled the engines out of afterburner, to full military power- never yank them below idle at such high speeds. The engines are automatically protected from dropping below full military power at such high Mach numbers, but I don't trust the automated systems to be working, especially on a test flight out of major maintenance. If the engine speed were to drop below 100 per cent of the normal fan rotation at such high air speeds, the fan blades would tear themselves apart!
“As the nose came back up above the horizon, the speed started to decay to Mach 1.4 or so. I let the aircraft zoom a bit, and further reduced speed to a more 'normal' Mach 1.2, before starting to pull it back towards home base. I had to lose speed and altitude to continue the test flight profile. While I was there, I completed the intake doors check- those are the doors just aft of the LEX fences that open above Mach 1.33 to alleviate intake pressure, and they don't close up again until below Mach 1.22.
“It was a very interesting experience, but the slow wobble of the nose had me imagining the famous opening sequence of the Wide World of Sports, where that ski jumper had a spectacular wipe-out. I was in no mood to push it any further; all aircraft have speed limits for a reason”, ‘Alf’ concluded, mentioning that he still has his original ¾ inch HUD tape of the incident.
CF-18 Hornet aircraft during Air to Air refueling exercises. (CF Photo by Private Laura Brophy)
‘Alf’ adds, however, that his experience pales in comparison to his father’s experiences. “My father used to fly the CF-104 (Starfighter) - he told me all about his first Mach 2 run. At one point, he was at Mach 2.2 plus and climbing when the SLOW light came on, which meant his intakes were overheating. He ended up zooming through 78,000 feet before heading back down”.
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