North American Navion
PUBLISHED: 12:45 29 June 2011 | UPDATED: 14:08 10 October 2012
A 100-hour pilot imported this 1947 North American Navion L-17-A, and he couldn't have chosen better
By Nick Bloom
Most newly qualified pilots are pretty cautious. They hire the club PA-28 and make occasional forays to a familiar airfield for a cup of coffee. Matthew Eames (37, father of three, a transport manager) is a little more ambitious.
Just one year from starting his PPL he has imported a 1947 North American Navion – the only one in the UK. After ten hours of dual training on type, he has now soloed the Navion... and he has just 100 hours on his licence. It was reading the 'Practical Aviation' article in Pilot on importing an aeroplane from America that inspired him, so, by way of thanks, he offered the Navion to Pilot for a flight test.
As far as we know, it is the first North American Navion in the UK – any others in the country are later models produced by other manufacturers.
First impressions are that this is a big, solid aircraft and that even the power of its 225hp flatsix engine (the aircraft originally had 185hp and has been upengined) might not be enough. However, the wing area is generous, the wings are slightly undercambered, which gives additional lift and there are enormous slotted flaps.
It is a beautiful aeroplane, finished in gleaming aluminium and in its original US military markings. The fin and rudder seem perhaps a touch on the small side. The undercarriage has long legs, so the cabin is high off the ground, but even from the outside you can see that it's a big cabin with big windows.
All four occupants have to form a queue in the right order and enter the same way: via a giant footstep and handhold in front of the port wing's leading edge, onto the wingwalk and down into the cabin. (No step, and therefore no entry on the starboard side.)
The canopy slides all the way back, so for the passengers in the rear stepping down to the floor from the wing is dead easy, which is one consolation for the step and handle – today's passengers brought up on airline travel might find that mode of entry rather Spartan.
Once in the back, expect oohs and aahs of delight because the rear cockpit is superbly roomy and is also fitted with some very large windows. The Navion has terrific rear seats. Matias Gomez Villafane, who as check pilot for the flight takes the right seat, gets in first, then me and finally Matthew, who’s sitting in the back.
It's difficult for the front seat occupants to come aboard without standing on the seats, because it’s a long step down to the floor and the instrument panel gets in the way. The crew seats are adjustable, but I find my knees uncomfortably close to the instrument panel by the time I've moved mine forward enough to be able to reach full rudder travel.
I have short legs, but the pedals could do with being brought a couple of inches aft. Possibly they can be adjusted and have been set up for a long-legged pilot.There are full dual controls, as you'd expect in an aircraft of this type. PEDAL POWER
The pedals are linked to the nosewheel and rudder, but not to independent brakes – the only means of stopping the aircraft on the ground is a handbrake. The rudder is linked to the ailerons, so your feet will bank the aircraft as well as yaw it... and you can steer (to a degree) with the yoke while taxying. The seats are upright and very comfortable, although it takes me a while to get used to having no shoulder harness and just a lapstrap.
The control yokes seem tiny compared with the rest of the aircraft, which is big, bulky and masculine.
The cabin doesn't seem very military, though, being rather luxuriously upholstered and soundproofed. There is time for a quick introduction to the controls before we have to join the camera ship for a streamed takeoff. The throttle, propeller pitch control and mixture control are all plungers, the throttle fitted with a vernier.
A few times during the flight I take my hand momentarily off the throttle and put it back on the pitch control by mistake – they're right next to each other and if you don't look, it's an easy mistake. Other plungers operate hydraulic pressure, carb heat and cowl flap; rather a lot of plungers, altogether.
Undercarriage and flaps are hydraulic and you have to remember to pull the hydraulic plunger out or they won't work... and push it back in afterwards so that the system stays charged. Pulling it out is one of the pre-takeoff checks.
The flap and undercarriage levers are small affairs at the base of the panel, the undercarriage lever protected in ways I'll describe later. Rather to my surprise, because they look like they might shorten the takeoff, Matias advises me not to use those generous slotted flaps until landing, so we leave them up.
He also advises me to have a look around and remember how high we are off the ground so that I don't 'bury' the aeroplane when I touch down – a common mistake for pilots who are lulled by the Navion’s handling into thinking they're landing a PA-28. To close the canopy you twist the large handle to release the locking pins at its base and haul forwards until the catch at the front engages.
Twisting the other way pulls the canopy the final half-inch, completing a very effective seal. It's a good system.
Time to get started. I reach up to the bank of switches on the roof for the master switch, fuel primer and mags, then down to push in mixture and throttle until the fuel pressure gauge reads maximum. I then crack the throttle and press the starter button and the big six-cylinder Continental rumbles into life.
After warming the engine, cycling the prop and checking the mags, we tell the cameraship pilot we're ready and follow him backtracking down Peterborough Conington's long runway. I'm taxiing with my arms crossed – right on the big brake lever under the centre of the panel, and left operating the throttle. I can tell that this is a heavy aeroplane, because it takes a firm pull on the brake lever to slow it down and a fair bit of throttle to get it moving again. The ride is firm and the Navion feels solid. SITTING HIGH
The view out at this stage is excellent to the sides, because you are sitting quite high in relation to the wings, and pretty good ahead. Directly ahead, the view is rather hampered by the fairly low roof and rather high instrument panel, but I've flown other aircraft that were a lot worse. The engine really does rumble – it's not just a figure of speech.
Taxying, once I've got used to the lack of differential brakes, is very pleasant, and the turning circle, when we need to turn around, is good and tight. During the taxi I try the rudder-aileron link, and it's true – you can steer a Navion like a car, using just the 'steering wheel'. I watch the Chipmunk we are using for a cameraship accelerate down the runway, wait until it has lifted off and then open the Navion's throttle.
With the weight of three souls and 90 minutes' fuel on board, the Navion moves forwards at a fairly brisk pace, but it takes a couple of seconds for the controls to come alive so that I can unload the nosewheel.
Elevator is neither light nor heavy during the takeoff run, making it easy to set the right pitch angle. At 60mph I rotate and we lift off at 70mph with only a slight nudge backwards on the yoke, but this feels a little early, so I hold the aircraft down until the ASI reaches 80mph before climbing. Initial climb rate with no flap and wheels down is around 700fpm. Now that we're established in the climb, I need to raise the undercarriage.
You apply the little finger of your right hand to a safety lock, a small flap under the instrument panel.
While pulling this sideways with your littlest digit, you grasp the undercarriage lever between thumb and forefinger and pull it first out and then down. The first few times you'll probably strain your little finger – as I do. The three lights that show green or red are with the switches above the windscreen. Climb rate with the wheels folded away is around 900fpm.
In the briefing we all imagined that the 225hp Navion would rapidly overtake the 145hp Chipmunk, but the two aircraft actually seem to be quite evenly matched and it takes a couple of minutes at full throttle to catch up. I gingerly draw alongside and begin evaluating the various blind spots – to be safe the two aircraft must be in sight of each other at all times – and how the Navion reacts to control inputs and different power settings.
The big side and rear windows make this a better than average aircraft for formation work and reduce the 'blind' areas. The aircraft responds quickly to throttling back, but more slowly to added power, which means it must be fairly draggy. It looks pretty well streamlined (especially with the wheels folded away), so this must be a combination of weight and wing area. The controls feel quite light for such a big aircraft and its manoeuvrability is excellent.
When the cameraman in the Chipmunk begins making hand signals – to drop down and back, for instance – it's easy to obey. Matias is asking what I think of the Navion, and I have trouble expressing an opinion. I am not entirely comfortable, at least not yet.
The aircraft has a slightly unusual feel, probably because of the oddly small control yoke, the seating position close to the instrument panel and the vernier equipped plunger throttle control, always rather awkward for formation work. I don't think it's because of the rudder being linked to the ailerons, even though in close formation I am sideslipping almost constantly. I can feel the link, but it isn't getting in the way.BREAKAWAY
As the photoshoot progresses I start to feel properly at home. For the breakaway shot I need to bank without letting the Navion drop under the Chipmunk, so I add top rudder. This holds the nose up rather well. And later, with fully crossed controls for the head-on shot, the rudder turns out to be surprisingly effective.
When I take the lead for the rear-three quarter shot, I am required to hold a steady
90mph without climbing or descending. It's easy in the Navion, which is obviously very stable as well as quite manoeuvrable. One thing I do find out from early in the flight is that the elevator can become quite heavy if the trim wheel isn't set right.
It's a small knurled wheel on the rather cluttered base of the instrument panel, somewhat low geared, but quite effective. It doesn't take long to become familiar with it. The cameraman gives a thumbs up, he's got all but the landing shots, which he'll take later. The Chipmunk banks away and we are free to see what this bird can do.
The Navion is not cleared for aerobatics or intentional spinning, but in the Utility category, which we just meet, since Matt and Matias are both lightweights, it is cleared for steep turns, Chandelles and Lazy Eights.
Sampling these gentle coordination manoeuvres greatly increases my liking for the aircraft, which turns out to have controls that would do credit to an aerobatic machine. Its roll rate is particularly good, making roll reversals a treat, and it is clearly capable of a low-G loop, aerodynamically, though it would be foolish to risk it structurally.
The level stall with full flap and undercarriage takes a long time to arrive, and I have the yoke pulled all the way back into my chest before it comes, a series of mild nods without any suggestion of wing drop.
The descent rate is marked, of course, but not dramatic. The stall in a steep turn (undercarriage and flaps retracted) is equally docile, the wings rolling level at the stall break. In both the level and the turning stall, I am heaving back on the yoke; few aircraft give this much warning.TOURING STYLE
During the flight back to Conington I am able to sample the Navion's style as a tourer.
Setting the manifold pressure at 23 inches and the propeller at 2,300rpm, the indicated airspeed settles at 130mph. At these settings, Matias has found the Navion to consume around 45 litres an hour, giving a cruise range of five hours to dry tanks.
The view ahead is a little restricted by the roof and a moderately high instrument panel, but is excellent to the sides and fine for navigation purposes.
The Navion is very stable and would ride well through turbulence. The linked rudder and aileron means you can steer with your feet quite easily, making the Navion a good instrument platform. All in all, it makes a fabulous tourer, and it's easy to see why a modified version of the design re-entered production in the Seventies as the Rangemaster.
Back in the circuit I have little difficulty in getting the Navion to slow down to its flap and gear limiting speed of 100mph. To lower the undercarriage you don't need to use your little finger on the safety catch – just pull and lower the lever. Another lever drops the flaps. These lower the nose and reduce stall speed, but they don't seem to have any bad effect on stability.
The Navion rides down final approach as if on rails... or it does until I realise I'm too high and go for a full sideslip, which the aircraft performs beautifully. A good sideslip usually goes with a high crosswind limit, an important advantage in a tourer.
I allow the approach to stabilise at 75mph, and make some final adjustments to the elevator trim. There is quite a stiff crosswind from the right, so I approach like a crab, heading right to stay lined up with the runway. With full flap at this speed you can see everything ahead over the nose. Elevator response during the roundout is good – neither too responsive nor 'soft' and we are now floating over the runway. I push left rudder and the Navion lines up.
Pulling the throttle all the way back, I feel the aircraft is about to touch down and ease back on the yoke, but this is evidently inadequate: we make a perfectly good landing, but on all three wheels at the same time. We fly a few tight circuits and touch-and-goes for the camera. During one I allow the speed to creep back on a low base leg and ease the nose down to recover.
The Navion loses quite a bit of height before the ASI needle creeps back to its previous healthy figure, a reminder that this is quite a heavy aircraft; get slow and low and final and the earth could 'rise up and smite you’. Retracting undercarriage after each takeoff is becoming routine, but I still sprain my little finger occasionally.
After that first landing I learn to heave back on the yoke before touching down. While in some aircraft this would have you zooming and stalling, it's necessary in the Navion – at least one that's been up-engined like this example – if you are to arrive on the mainwheels and then lower the nosewheel. IN A FLAP
For the final touch-and-go, we leave the flaps down to see how they alter the takeoff. They have a wonderful effect. Previously, on opening the throttle the aircraft has surged forwards but run perhaps 100 metres before being ready to fly. With full flap, it lifts off much earlier and although I cautiously hold the aeroplane down before banking and climbing away, it feels ready to go immediately. Handling when I do bank and climb is unaffected.
During the last week, Matias and Matt have had a busy schedule, assembling the Navion after its trip in a container across the Atlantic and test flying it. The next task after arranging its debut in Pilot is to take it to its new base, Eaton Bray airstrip.
Matias will assist Matt in adapting to safe operation from a modest grass runway. I'll bet the key to short takeoffs is to use flap, and no doubt this is something the pair will be exploring. Matt should have a lot of fun with his Navion. It takes courage and imagination for a low hour pilot to import a 1947 military aircraft, and I'm sure we'll be hearing more about Matt's choices in the coming years.