Nigel's notes on the Aeros Phantom

OK. I'm going to ramble about the Aeros Phantom because rambling on the web is what I do.

They don't make them any more (see the Aeros web site) but, as I read elsewhere that they only ever sold about 150 of them, I guess that didn't even make enough money to cover the development work. This is really sad because it has everything the engineer in me thinks a hang glider should have. I fear there will never be a mark two.

Well "has everything" is pretty big statement from a 'know nothing' newbie still struggling to land on his feet consistently. However after too many years in instrumentation physics, quite a bit in the aero industry, I'm pretty bitter and twisted about the crummy level of engineering the world seems to want to serve up to me.

Here, on the left, is another of my gliders. This one is the old friend that I did much of my initial training on. It's another Aeros called a Target. This is a good, solid, dependable training glider that will do its best to be controllable and predictable. In the picture the A-frame is folded so it lies down so it isn't going to get blown away. This enables us to see the profile of the wing more clearly.

Well the first thing you will notice is that the wing is a sail stretched over a frame with battens, or ribs if you want to be pedantic, inserted into it to control the shape. There are also wires, a bit hard to see in the picture I know, coming from the top of the king post and pulling up on the back edge of the sail in places. This is the most significant difference between the hang glider and the paraglider. The wing of a hang glider is shaped mechanically while on a paraglider it is shaped by the air flowing through it. This is, I confess, one of the reasons that I'm not brave enough to fly a paraglider.

Now this wing is a very clever design. Various parts of it give lift and they all vary as to how much lift they give depending on the speed of the airflow over the wing and the 'angle of attack', that is the direction the airflow hits the wing. The idea is that if everything is going well all those bits of lift add up so they are net pulling up at a point just in front of the king post so this is where you hang the cargo. I'm sorry. I mean the pilot.

The pilot holds onto the 'A-frame' which, on the Target, is solidly wired to the wing and pushes it about. Now, of course, since they are hanging from a strap they can't push anything but what they do is pull themselves forward, push themselves backwards, or left or right relative to the wing using the bar. This changes the balance of the craft and it moves to correct the forces applied. Hang gliding is wonderfully unsubtle in that everything you do to control it depends on where you put your bottom.

Wing span13.29.6m
Aspect ratio12.95.7
Load weight50-10060-114kg
Breakdown length5.8x0.5x0.25.7/3.8/2.5m
Min sink rate0.65m/s
Min airspeed33-3525km/h
Max airspeed11081km/h
Best glide ratio19.59
Mouse over for imperial measurements.
Wing span4331ft
Aspect ratio12.95.7
Load weight110-220132-251lbs
Breakdown length19x1.6x0.6518.7/12.5/8.2ft
Min sink rate128ft/min
Min airspeed20-2215mph
Max airspeed6850mph
Best glide ratio19.59
So what's in the design of the wing? Well the important bit is 'washout'. A proper aerodynamic description of washout goes far beyond what we need to know here but basically you arrange the washout so as the wing approaches a stall, that is the point where it is either too steep or too slow to continue flying the parts of the wing further back still give lift while the parts at the front are failing. This means that the rear end goes up pretty much regardless of what the pilot does and the wing dives, goes faster and flies out of the stall. The key thing is that it is continuing to fly.

There is no disagreement that 'continuing to fly' is really good news. Early hang gliders, with no stiffening in the sail and hence no controlled washout, suffered from a disastrous problem called 'the luffing stall'. Basically if the nose got pointed down too far the wing just flapped loosely and gave no lift and critically no control to fix things all the way to a very nasty impact with the ground. OK, if you stall a modern hang glider too low it might still hit the ground before it dives enough to regain its airspeed and fully recover flight but at least it tries and it isn't a total fall out of the sky scenario.

However the wing of the Target is built to save beginners and it's not actually a very efficient wing. The Wright brother's 1902 glider, held by many to be more innovative that the Wright Flier made the year after with an engine in it, incorporated the discovery that a larger aspect ratio (length to width ratio) made for a much better wing and we are sacrificing that.

So what's the alternative? Well keep the washout but sweep the long thin high aspect ratio wings. Now this demands a level of rigidity that the Target does not need but again, as you approach the stall, the washed out tips are still giving lift while the core of the wing, well forward, is failing and so the nose is going to drop and the speed comes back on. What we are building now is a modern aeroplane.

Sadly all this rigidity comes at a price. The Target weighs in at 25Kgs ready to fly while the Phantom is 38Kgs and the higher level of complexity means it take about three times longer to rig it out of the bag to be ready to fly. (Well it takes me three times as long.)

OK, so we are dealing with a real aeroplane now, so what other differences do we get? Well the first is real control surfaces. That is real ailerons to control roll and hence turn and real flaps to increase lift at lower speeds so we can shape the wing to choose between higher speed flight or a slower speed landing. Aeros also add some things they call SPADDs (Split Aileron Drag Device) to make up for not having a rudder and help us do coordinated turns. A SPADD is an aileron extension on the wing tips that only does up not down. One final tweak is the addition winglets on the wing tips. These are there to stop there being so much airflow from the top of the wing to the bottom of the wing round the end which is a shortcut and means that the ends of the wing wouldn't pull their weight on the lift front. Since they are part of our stall recovery trick that would be a bad move. As they improve wing efficiency you will see them on quite a lot of aircraft these days. They just mean you get more working wing for your span.

So what does this give us? Well we have the high aspect ratio wing so it offers more efficiency and in a glider that means we get more travel horizontally for the amount of height we consume (remember that gliders are always flying down through the air like a cart rolling down a slope). This means you go faster and go further before you have to find some more air that is rising faster than you are descending to put you back up into the sky again. There are a whole bunch of other detailed features to make it a better glider but, as a result, it is more picky and more demanding on the pilot. Yes, it can deal with an amateur quite well but to wring out it's full performance needs a finer pilot than I am.

Right so where do I come into this? Well one day I was up on a hill, Devil's Dyke just north of my home in Brighton, not flying but just walking about looking nervously at the paragliders and wondering what I was looking at with the hang gliders. OK, there were a lot that I recognised as being like my Target and the Rio 15 but there were a couple that I recognised as being of the 'Kingpost-less' type because they didn't have Kingposts. I realised that that meant they had nothing to pull up on the sail but, as I could see they maintained their wing shape they were 'Rigid's. I was learning the words back then. Some of them had spoilers on the top of the wing so they evidently used that to control the turning. Big spoilers, for normal flight, offended me.

Turning is the problem. A modern aircraft with a modern pilot in it does a 'coordinated turn'. A coordinated turn is when the pilot uses the controls so that the aircraft banks as it turns and adjusts so you get no sideslip, no lateral acceleration down the slope of the bank and no unplanned height change. As an airline passenger you assume this as the aircraft changes course you see the wings tip but your drink does not slop about in your glass. A good coordinated turn is the smooth, efficient way to do it and is the hallmark of a good pilot. On a glider we like the word efficient as we have no throttle to open to put back the energy we wasted doing it wrong.

Now a glider like the Target does quite a reasonable turn but it's hardly fully coordinated because all we are doing is moving our centre of gravity relative to the centre of lift and that tips the wing rather than banking it. Proper bank control needs proper ailerons and a rudder.

As I walked about suddenly one glider stood out. It had ailerons. I stopped and stared. I wasn't expecting ailerons because... well because these were hang gliders weren't they? Weight shifting was their thing. So as soon as I saw them I was interested. It had flaps too. I was suddenly looking at what I mentally considered a real aeroplane. This was a hang glider but with real flying control surfaces and all those years in the aircraft industry sighed with happy approval. I was looking at an Aeros Phantom and it was love at first sight. Look at the pictures. Can you really blame me?

So yes, this one is mine. After my introduction it was still just a pipe-dream and I wasn't even looking for one but, a couple of years after I first saw one, I saw this advertised and knowing they were scarce and only going to get scarcer I caved in, paid the asking price and took it home. I consider that I have laid it up, like a fine wine, for when I can enjoy it.

The path for me from wanting to fly a hang glider to actually flying has been long and hard but the knowledge that my Phantom is hanging up in my home, warm, dry, protected and waiting for me has sustained the drive through the bad times when I knew I was just having to get on with other things and wait. Even when I had learnt to fly it had to wait. The advice is that you needed at least 60 hours of airtime, yup, that's two and a half days in the air, and that sounds a good call. Once your flying hours are counted in days then hopefully you have the good habits and skills to manage an unfamiliar glider and the personal discipline to be very careful in your procedures. I have to admit that one of these has quite seriously injured a pilot I like and respect because, so I was told, he was distracted at a vital moment in his setup procedure and failed to complete a step that does not exist on an 'ordinary' hang glider. I have taken this as a salutary warning for myself.

tl;dr I fell madly in love with this long slim Ukrainian bimbo who takes forever to get ready, promises the earth, wants to spend all my money, tries to make me run faster than my poor little legs can go but, on a good day, she lifts me to the skies.

As a note to myself the rest of the pictures are on the 2012 reel.
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