PUBLISHED: 12:44 29 June 2011 | UPDATED: 14:08 10 October 2012
Superb for systems and numbers, and an economical IFR tourer
By Nick Bloom
Since I last flew a Liberty XL-2, there have been a number of improvements. That was a few years ago, so I am looking forward to reassessing the type. The latest version is called the Vanguard. I flew its predecessor (reported in March 2007 Pilot) with Tony Creese, at that time Cabair’s senior CFI, from Elstree, which has a runway only 651 metres long.
We both felt that the Liberty we flew lacked performance for students unless the runway was longer, but there were subsequent suggestions that we had been briefed to approach too fast and that the aircraft was fitted with a coarse-pitch propeller that gave a good cruise speed but a longer takeoff. We had some other criticisms, most of which have been put right in the Vanguard, so a second look was certainly justified.
You still enter the aeroplane by sitting on the wing leading edge, but a step has been fitted which gives you an alternative of walking your way into the cockpit. I found entry pretty easy this time, and those big gullwing doors certainly help in this respect. I also found the door closing mechanism improved; it is now very positive, though apparently one of the preflight checks is to verify the rear pin is engaged by pushing on the door with your elbow.
My companion for the flight, Paul Everitt (Liberty’s business development manager who is also a flying instructor), tells me a door warning light is to be fitted soon to get round this. I really like the winding handle for adjusting the rudder pedals and the change from finger to toe brakes. The FADEC system obviously squeezes more performance from the Continental engine, but it does add several items to the preflight checklist. This is in character for an aeroplane that does seem to be designed to prepare airline pilots to deal with systems. RUGGED OR LUXURY
The seats are among the most comfortable you'll find in any light aircraft, and the standard of interior fitting out is extremely good. Apparently there is a more rugged upholstery option for schools, which can then have Liberty fit the luxury interior when the school is ready to sell the aircraft to a private owner as a tourer – one of many instances that show that Liberty listens to its customers.
Paul runs me through the start-up checklist, which as I’ve said is a little longer than on other trainers. He hands over for me to taxi the aircraft. It taxies very well and another point in its favour is the very tight turning circle you get with the free-castoring nosewheel.
The last time I flew a Liberty it had the Sensenich cruise propeller rather than the
rather finer-pitch MT propeller fitted in current models. This rather hampered its takeoff performance, and I'm looking forward to seeing how this later model compares. The Liberty certainly has a lot going for it with the Aspen avionics, which make it a very economical two-place IFR tourer, actually the only two-seat IFR tourer currently in production in America.
The addition of the Aspen avionics also makes it an ideal entry level glass cockpit trainer. The aeroplane is very fast for its horsepower and returns a good cost-per-mile. Its rugged construction should give it a long life in a training environment.
We line up, set 20 degrees of flap and I apply full throttle. The aeroplane is light for its horsepower and it surges forwards, but the wing area and section are designed for cruise rather than lift, and the takeoff run does seem rather long compared to the trainers I've flown before. Again, this is excellent providing you have a long enough runway, because a trainer that leaps into the air is a poor introduction to flying bigger aircraft.
A long takeoff run gives the student time to monitor speed and first rotate, then lift off as two separate actions. Following Paul's direction, I raise the nosewheel at 60kt and allow the aircraft to fly itself off. I estimate the takeoff run to be around 450 metres, which is fine for all but a few UK airfields like Elstree and a handful of others with short, or relatively short, grass runways.
I suspect the UK is almost unique worldwide in training from runways under 1000 metres and most training airports today have runways at least 50% longer than that. CONTROL ‘FEEL’
The initial climb rate is around 600fpm. Raising flap gives rise to some sink, nothing serious, but again a good point in a trainer. The aircraft needs some right rudder in the climb. The elevator control previously struck me as having some friction, but this is no longer evident in the current model. All the controls feel as though they are linked directly to the control surfaces and the aircraft now has a good 'feel', giving the pilot plenty of feedback.
Control harmony is a little unusual, with light rudder, moderate elevator and very light ailerons, but the controls are exceptionally pleasant and the aircraft comes across as very manoeuvrable as well as stable.
The aircraft is actually very smooth and this would make it a good instrument platform. In particular you can steer on rudder alone very effectively, which is great for the high cockpit workload during training. I find a mild left wing drop during the level stall, both without flap and with full flap. However, the level stall with full flap is exceptionally docile, and becomes even more so when there is a trickle of power.
During a turning stall, though, the aircraft rolls the wrong way, into the turn, and drops its nose, so there are limits to its docility. This is good in a trainer, because students may go on to fly aeroplanes with less forgiving stall behaviour. What strikes me about this aeroplane is how very good it is at teaching flying by numbers. It is not bad for teaching 'seat of the pants' flying, but that really isn't its character and in any case is going out of style (except in the microlight world).
Most students chasing a PPL today have touring or commercial flying in mind and don't want the equivalent of a Tiger Moth or J3 Piper Cub as their first exposure to flying. For instance, adjusting throttle via the FADEC, you have to wait for the rpm to settle.
The elevator forces change at different speeds and power settings and trimming out works better if you jab at the trim switch, then wait for everything to settle. It pays to use trim at different throttle settings and speeds. The relatively low 80kt flap limiting speed is also good for teaching anticipation.
All of these features make this an ideal preparation for bigger, more complex aircraft, assuming that is what the student wants. The instrument panel comes up higher than in some trainers, and the roof is a little lower, but again, this is good preparation for IFR flying.
The view out is good enough for initial lessons when students are learning to fly by attitude, but you want them to become more instrument aware later in the course and a big, well-equipped panel is appropriate. The aircraft's stability and quite powerful controls (especially aileron) make it very pleasant for steep turns, turn reversals and just stooging around.
Despite the slightly 'letterbox' view ahead, the view to the sides and down is excellent. The cabin is very spacious and comfortable. All of these elements make the aircraft very pleasant to fly.
While I was cruising we achieved 124kt TAS at 4,500ft at 66% power, consuming 5.5usgph. All of this information was available via the aircraft's flatscreens, which convey an astonishing amount of data once you learn how to use them.
Departing from an international airport, you need a lot of information and Paul gave me an impressive demonstration of just how easily this can be dialed up on the right-hand screen. Having said that, he still carried a thigh pad and noted the numbers down – good practice and a good example from an instructor.EXTENDED FLOAT
Landing on Elstree's relatively short runway had been a little challenging. When I try this time at an airport with a longer runway, I am still struck by how much the Liberty floats after rounding out. Even by reducing the approach speed to 60kt, we still use quite a lot of runway, though not more than was required for takeoff.
After several tries, the shortest landing Paul and I can manage between us is probably around 400 metres. However, this is with a 6kt tailwind, which equates to a landing distance of 320 metres in nil wind. (The only available airport had everyone landing downwind that day.)
The toe brakes are a great improvement over the finger brakes the aircraft had originally, reducing landing distance by a good 50 metres. Of course it is one thing for experienced pilots trying for the shortest possible landing distance to land in 320 metres and quite another to expect this of students who have just begun learning to fly.
In summary, the Liberty deserves the great success it has been having in selling to flying schools. It's a rugged little aircraft, economical to operate and exceptionally comfortable.
I think Liberty has the balance between teaching 'seat of the pants flying' (flying by attitude and feel) and flying by systems, numbers and checklists exactly right for today's training environment. A design like the Liberty needs to earn its keep as a tourer as well as from instruction, and the Liberty is eminently well suited to this role too, with plenty of endurance, comfort and a good cruise speed.
The only possible downside of the Liberty is that it isn't suitable for training on runways less than 1000 metres long. However, had it been designed for short-field training it wouldn't be as economical (you'd need more power), or efficient as a touring aircraft (because you would need more wing area and that would create drag). Losing a tiny percentage of the training market is small price to pay for a design so well suited to the vast majority of customers.
Incidentally, one thing Paul and I did discover from our attempts to land and takeoff in as short a distance as possible is that the Liberty is a great aircraft for teaching short-field technique. Get everything right and it can cope (two-up) with a 400-metre runway. This could be taught to students and it would be a great preparation for other aircraft. In this respect old-style trainers like the Tiger Moth, Piper Cub and Cessna 152 made things too easy and the Liberty is a better trainer.