Dragon GL3 portable glidepath indicator
Originally designed for the military, the Dragon GL3 portable glidepath indicator brings big-airport tricks to grass strips or remote helipads.
Words: Pat Malone Images: James Ram/Westcountry
So you’re flying into a strange strip in an area that is unfamiliar to you and, just to make it interesting, it’s getting towards dusk and the evening mist is beginning to coalesce in your brain. The cross you made on your chart doesn’t seem to conform to any visible ground feature, and the field you were assured would stick out like a sore thumb blends seamlessly into a greying landscape.
Suddenly, a flashing red light stabs out and catches your attention. There, on the beam, is your destination ? obvious, really, you don’t know how you could have missed it. You turn towards the light, which changes slowly to flash red and white, and you descend with the glideslope, wondering what on Earth you were worrying about.
Your little friend here is the Dragon GL3 portable approach lighting system, which brings big-airport tricks to grass fields or remote helipads. It sets up two lights, white and red, on a glideslope you choose yourself, and is visible for more than five miles ? much further, if it’s getting dark or the weather’s on the turn. It’s easy to set up, easy to use and a bit of fun; whether it crosses the all-important divide between ‘nice to have’ and ‘desperately needed’ is for you to decide.
The GL3 was designed for the military, and is also used by the emergency services ? largely for helicopter approaches to improvised landing grounds amid flood and carnage. But private owners have also bought them for approaches to their homes in low visibility, at dusk or in iffy weather. And indeed, the portable approach light system is very effective.
The Dragon GL3 looks a bit like a copper’s radar gun and isn’t much bigger, if a tad heavier at 5.7kg. Minimal training is required to use it, it says ? and it is true. Despite the fact that I’m a technophobe who still hasn’t worked out why my TV has two zappers, I set it up in three minutes after watching a short how-to video on YouTube: monkey see, monkey do. The average 11-year-old could probably erect this puppy quicker than I did: plonk box on tripod, attach bits, plug-in and presto! Check the sight glass to make sure it’s just about level, switch it on and consult the digital readout below the lenses for the glideslope angle. (It doesn’t rely on the sight glass bubble for the approach angle ? it’s much smarter than that.) You nudge the angle up and down with a switch on the side, and the only thing you have to remember is that if the reading is too high and you need to lower it, take the digital display below the value you want and nudge it back up to the right level.
You bolt a compass on the back, which helpfully reads backwards so you orientate the projector to the compass reading the pilot will be flying his approach on. There’s a screw-on clinometer that’ll tell you exactly what the approach angle needs to be if you have trees, pylons or any bloody wind farms nearby. Choose whatever glideslope you like from 2.4 to 15�, in gradations of 0.1�.
Looking down the business end of it, the display is beyond simple ? white light, too high, red, too low, alternate red and white, just right. You see a single blinking light at any one time. If it’s red or white it pulses twice a second, but if you’re on glideslope and you’re seeing both, you get four flashes a second, two of each. The lights sort of segue into each other, so you get a hint of warning that you’re wandering off the glideslope before it actually happens. If you’ve ever used a PAPI or a VASI, it’s like that, only easier. The lights have three brightness settings, the highest of which impinges on battery life, which is about five hours between charges.
I took it to Bodmin Aerodrome and popped it on the end of Runway 31. Now, Bodmin ? one green field among many ? has a reputation for being well-hidden, and even locals sometimes have to look a little harder than expected. The trick is to follow the A30 west and turn left at the BP service station just east of the town, and it’s two fields over.
I shot a few approaches in the Robin, and the GL3 did exactly what it said on the tin. The real value, I thought, was in bringing the aircraft right to the numbers. For example, 31 ? the ‘long runway’ ? is 480 country metres, so if you don’t get wheels on quickly enough, you might just be dicing with the coppice next door. I flew out to five miles to check the power of the light on the middle setting and found it still very bright at that distance; this was around 1530 on a slightly dull February afternoon. (The makers say that bright sunlight reduces its effectiveness to two to three kilometres, and it’s designed for dusk or night-time operations.)
I left the box out for much of the afternoon, and everybody had a go and liked it ? not only for the glideslope, but for judging the base-final turn. The cut-off at the edge of the beam is abrupt; it doesn’t fade into view. Military chaps value this feature. If you’re being a bit Secret Squirrel about where your helicopter landing site is, you don’t want to be scattering light profligately. Instructor Matt Culverhouse said a student who was having difficulty rolling out on the centreline could use the beam to help judge his timing.
It’s in the helicopter world that the Dragon comes into its own. We have some fairly low-tech tricks for keeping helicopters on the straight and narrow. Robinson R44 owner Rob Palmer suggests using three dinner plates, set out a metre apart in a triangle. It’s amazing how far away you can see three decent-sized dinner plates, and they make it relatively easy to judge distance and approach.
Rob owns the excellent car sales company Exeter Diesels, and keeps his helicopter (G-HAGL, geddit?) at his home a few miles from the city. The site was chosen for its beauty and tranquillity, not for its approachability. It sits in the folds of a Devon valley, occupying a slightly dog-legged, narrow hollow facing the west, with the hangar and helipad halfway up the hill on the south side. To the west, the National Grid guards the entrance to the valley ? the big, 400,000-volt jobs, marching across a ridge ? and to the south lies a neighbour’s noise-sensitive stud farm.
Behind the ridge on which Rob’s house sits is another valley, so when the prevailing wind is blowing from the south-west, you make a downwind leg over the wires, with ground level rising and falling sharply beneath you. Make your base across a valley with an eye on vertical speed indicator and then drift, turn finals a little high to get over the ridge and over Rob’s roof, then down to the helipad. Keep tight control of your speed because your go-round options get progressively less attractive quite a long way out, what with the hillside ahead and the wires on your flank ? and if you get a whiff of vortex ring, it’s goodnight nurse. Coming into an east wind, you’ve the wires to clear on finals, then it’s a relatively steep approach into the hillside until at about 100ft, where you’re either well set up or you go round. I’ve never approached from the north, but Rob tells me the winds swirl through the valley in such a way that even he lands somewhere else and walks home.
So, it’s a good place to play with the Dragon ? never mind the rise and fall of the ground; never mind the pucker-factor of sailing close to the wires; never mind the capricious winds that snake through the hills ? just acquire the beam and ride it down, and your only concerns are speed and distance.
Again, setting up the GL3 was the work of minutes, and after some messing about at the bottom of the valley for the photographer, I set it up for a 4� glideslope to give me ample clearance over the pylon on finals. I flew out a couple of miles and imagined I was a new customer who’d been invited down to look at a motor and given an approximate approach area. The lights are visible a long way out ? you couldn’t mistake them for anything else ? and the lateral spread is 16�, meaning that at five miles, the beam is more than a mile wide.
Starting from 1,000ft agl, I flew a straight-in down the red beam until it started to sublimate towards white, commenced a descent and ran straight into the pad, directly over the top of a power pylon, secure in the knowledge that I wasn’t going to get my tailboom stuck in it. Obviously, it doesn’t give you any distance information, so you can only use it in conjunction with your usual situational awareness clues. But while I know the pad quite well, I’m pretty sure that if I was a complete stranger to it, I’d be able to make a safe and steady approach using the beam.
Pros and cons
This is perhaps where the Dragon works best in the civilian world ? for strangers visiting challenging helicopter-landing grounds. If you’re coming home at night and your ground lights are activated from the cockpit, the Dragon can be made to work in conjunction with your system by the addition of a radio-operated switch between battery and battery tester. That gives the kit an extra dimension, but for many of us, I suspect, the cost is a dimension that trumps many others. The people at Cornwall Flying Club made strange little choking noises when I mentioned that the Dragon GL3 cost �12,000: one of the members bought an airworthy Cherokee for that last year.
As you’d expect, something this simple has to be pretty complicated. It uses a series of paired projector lenses and prisms, which must be heated to keep condensation at bay. It uses separate colour channels, rather than splitting light as some fixed installations do.
A lot of the instructions betray the unit’s military origins: how to operate it in the dead of night with no outside light sources; how to anchor it by digging it into the ground or packing stones or sandbags around it; and the injunction ‘not for explosive environments’ is probably not aimed at the civilian world. It has a number of fail-safe features; if the beam deviates by half a degree, perhaps because someone has tripped over the tripod or helicopter downwash has knocked it off true, it shuts down, and it comes back on within a second as soon as it’s been restored to level. You can power it from the mains or a car battery with an external adaptor?it is entirely waterproof and doesn’t take much maintenance.
Inventor and manufacturer Gerard Bauer says that, as well as the armed forces, the Dragon has found a home in the disaster-relief business, where picking a landing spot out of chaos in conditions of poor visibility comes with the territory. But you’ll find them on the grouse moors, and in places where helicopter owners have arranged to meet. “They’ve also been bought by commercial operators who want to extend their night capability, and by private owners who want more peace of mind when returning home late or in poor weather.” That’s all very well if you can get over that �12,000 drawback ? but then, not everyone is as poor as you and me.
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