HAWK Vario System

I've been flying with LXNAV's new HAWK vario system. To explain really quickly, it isn't a Total Energy vario. It works like this: if you can model the performance of the glider, and you can keep track of the attitude and airspeed, then you know what the resulting flight path should be. Now watch what the real flight path is. The difference between the model and the reality is the movement of the air. This is a crude description of what the system does, but it shows you what the system is aiming to achieve: a measurement of the three-dimensional velocity of the air mass. Split this 3D wind vector into the horizontal component - wind - and the vertical component - lift. The result is a fast accurate wind readout and a variometer that miraculously shows whether the air is going up or down. Experienced pilots have been able to do this in their heads - to some extent - for a long time, but the latest generations of computers can do it much more accurately, just as they can fly drones, land rockets on their tails, and so on. And we can't do that at all!

Fooled by Wind Shear

I've been using HAWK for a while now, and I've noticed something: I've been completely fooled by much of the wind shear within and around thermals. I thought I'd got it licked, but it turns out that I haven't understood it at all. It seems that around the boundary of single or multiple cells of rising air there is often a "soft" transition where the speed of the flow (the wind) changes enough to drive the Total Energy (TE) needle up or down by a couple of knots or more for a few seconds, but you can't feel a gust! This is why we often start a turn in completely the wrong place using our old TE variometers. Endlessly irritating. The HAWK vario is simple - wait until it says you're going up fast enough then turn hard right there - you simply don't miss the core. Well, you can still turn the wrong way, but you know what I mean. This translates into far fewer wasted circles. 

Understanding Air Movement & Errors

So an interesting step forward. I hesitate to say "Doh, just buy HAWK" because I'm not writing this to sell kit, I just want to educate soaring pilots. But having some experience with the system now, flying one glider with HAWK and one without, I understand more about the airmass movement and am more able to deal with the errors built into the TE system. This is a work in progress, so I'll get back to you sometime and update you on what I've learned over the summer. And will I put the HAWK system into the two-seater, bearing in mind that I'll have to replace the vario, maybe build new panels with all that entails? Probably. If I can afford it. Hah! Buy some more copies of the Soaring Engine and I will!

Fly safe

G

Editors Note, we invite you to "Ask G" with your questions to be answered in a future article by G Dale.  What's your question?  Curious about soaring weather?  Glider fundamentals? How does a particular instrument work?  Sailplane preparation?  Something else?  Let us know and send an email.  Time for you to Ask G.

Banner photo by Sean Franke. Graphics by G Dale

   G Dale is the popular author of The Soaring Engine book series.  He follows the endless summer, working for the British Gliding Association, The Gliding Association of New Zealand, and the Gliding Federation of Australia, always teaching cross country flying. He’s also flown and worked at various gliding clubs around the world: at Nympsfield as Chief flying instructor, at Booker again as CFI, at Lasham as DCFI and soaring coach, and at Glide Omarama as head coach, with visits to Minden, Serres, Takikkawa, Narromine, Lake Keepit, and many other clubs as a peripatetic soaring instructor and mountain flying coach.