Jets vs raceplanes Part II

Matt Hall and Ben Murphy explain the differences between military aircraft and the raceplane

Hall in his Edge

One thing all Red Bull Air Race World Championship pilots have in common is a fascination with flight. Some flew commercially, some became instructors and others joined the military. This is the second part of how a military jet differs from a raceplane. In part one we spoke to Cristian Bolton, François Le Vot and Martin Sonka about their experiences. In part two we speak to former Royal Australian Air Force Wing Commander Matt Hall and former RAF Red Arrows Team Leader Ben Murphy.

Hall spent many years flying the F18 Hornet and knows it inside out. "Obviously there's a massive difference in speed, so there's no need to go into that, but a raceplane will out accelerate a clean F18 Hornet – meaning it's carrying no weapons and no external fuel tanks," explained Hall. "But the Hornet will just continue to accelerate to its maximum speed. The raceplane has a better power-to-weight ratio than a Hornet," he added.

Murphy, who flew a Hawk in the Red Arrows agrees. "Obviously, the Hawk is much faster; but the raceplane is much, much more manoeuvrable and can pull considerably more G," Murphy noted. "For this reason, I find that the raceplane is much more demanding to fly well," he explained.

In terms of manoeuvrability, most jets have inertia so they take a long time, in comparison to a raceplane, to start and stop moving. "The Hornet has a G-onset rate of around 6g per-second," said Hall. "So if I fully pull back on the stick in a Hornet its G-limit is just over 7g and it will take a little over a second to get there. The raceplane can go to 12g (my MXS-R could go to 14g) and has a G-onset rate of 40g per second, so you can get to those limits of 12g or 14g in just over quarter of a second!"

Hall early on in his military career ©Photo courtesy of Matt Hall Racing

Hall continued: "It's the same with rolling the plane. The raceplane has a roll rate of 400-degrees per-second and that's instantaneous. You can get to top roll speed straight away and start and stop the roll instantly. In the Hornet when you roll it, it takes time to wind up – you can get it to roll quite fast – but it'll take a whole revolution to accelerate to its roll rate and then stopping it, you have to allow for the inertia. So typically in a Hornet you have to stop the roll at 60-degrees from where you want to be because it will slow down to that."

Hall also said that when he takes his Hornet friends flying in a two-seat Extra he asks them to fly a roll and they struggle to get their timing right. "They always under roll. That's because they take the aileron out with about 60 degrees to run and it's very hard for them to drive their hand to maintain the roll as they're not used to having something stop so quick. They can also over-G the raceplane because they're not used to the onset rate," he explained.

Murphy explained why jets need 'help' with the controls. "A military jet is so heavy, and the aerodynamic loads on the control surfaces are so huge at high speed, that the controls would be impossible to move by physical effort alone. So the control surfaces are moved by hydraulics (generally by a fly-by-wire system) and then the aerodynamic load is 'simulated' to the pilot by an artificial feel system - so the feedback is nowhere near as real as in the raceplane. In most cases, a military jet's computer will limit the pilot's input if it thinks it might put it outside of the safe flight envelope - we don't have anything like that on the race plane so the pilot is truly in charge!"

Murphy during his military career ©Photo courtesy of Ben Murphy

For any motorsport athlete 'feel' of the machine is exceptionally important. The raceplanes are direct connect, "Which means no matter what I do with my hands on the control stick, it will directly affect how the control surfaces move in the air," said Hall. "So I feel the air loading on the control surfaces through the stick in my fingers and I can feel the aircraft. The more modern jets are all fly-by-wire, so there is a more synthetic feel through the stick. The stick is just being used as a traditional type of controller, you tell the computer where you want to go and the computer decides the most effective use of controls to get that way. So you're not finessing the aircraft, you don't have that raw connection," he explained.

Although they are both flying machines, Murphy knows they have completely different roles to play and as such have to be flown differently: "The job of flying a military fast jet is actually more about 'operating' it than 'flying' it – operating the weapon systems, self-defence suite, navigation systems, reconnaissance systems, etc. The aim is to put bombs on target – the flying is only one part of it. Having said that, a lot of what I learned flying the Harrier at high speed and low level is applicable in the Air Race. And certainly flying in the Red Arrows gave me a lot of experience operating at the limits of the aircraft close to the ground – whilst thinking about wind, terrain, crowd safety, etc."

You might be surprised to hear that a raceplane is a lot nosier than a jet. "The loudest thing is the air conditioning. Every pilot in the Air Race will have a headset with noise cancelling features," Hall said. "The jet has better visibility – they're designed for you to be looking at what's going on around you. And the raceplane is designed to be as clean and light as possible and you only need to look out the front to see the next pylons. In a jet you also have a lot more instruments and a lot more to operate, where in a raceplane you set it up for when you're in the track, but once you're in there, you're not doing any systems management you are just purely flying the aircraft!" Hall added.

In the air with Hall and his F18 Hornet ©Photo courtesy of Matt Hall Racing 

Murphy is only in his first season as a Master Class pilot and has only raced his Edge 540 once, but it has already found a place in his heart. "I'm extremely lucky to have experienced both types of flying – but for me, piloting the raceplane is as close to 'raw' piloting as you can get. And as someone who loves to fly, that wins hands down!" Murphy concluded.

Both Hall and Murphy will be taking on the 12 other Master Class pilots next week in Cannes on 20-22 April. Watch them put their air force skills in action by getting your tickets HERE.