Where Did My Engine Go? – First Attempt at Gliding!

Sit tight and grab some popcorn. This is going to be a very long post :).20141011_102914

Imperial College Gliding Club is the oldest and one of the largest university gliding clubs in the world, having started in 1930, with a current membership of about 70 people, and owns 3 gliders. And we get crazy subsidization from the university, so it’s very cheap!

7:30 on a Saturday morning, we departed Imperial on a minibus for Lasham Airfield, a little more than an hour away from central London. It sounds far… and it is, and that’s mostly Heathrow’s fault.

The entire London airspace is class A down to ground, which means all aircraft operating in this area must be IFR (flying by instrument, under ATC control), and since gliders obviously can’t IFR (we don’t even have radio!), we can’t fly in the vicinity of London.

1 hour of bumpy sleep later, we arrived at Lasham amidst miles and miles of farmland! I was especially excited since I haven’t seen any empty space ever since arriving in London about a month ago. London = people + people + people + buildings + people + people.

Lasham is an ex-RAF airfield that is almost 100% devoted to glider operations nowadays, and is the home of Lasham Gliding Society – the biggest gliding society in the UK, and the club with which the Imperial gliding club is affiliated.

They held a morning briefing at the beginning to discuss weather, etc, which is really cool. Apparently weather systems work the same way in the UK as in Canada!

I was a little surprised that they actually set up the launch point on the runway, then someone explained that that’s because gliders don’t land on runways, so the runway is in fact the safest place to be on the airfield. Cool, eh?

At Lasham they have 2 main launch methods – winch and aerotow.

A winch launch is when a winch on the opposite end of the runway pulls in a cable that’s about as long as the runway, attached to a glider on the other end. The glider is accelerated from 0 to 60 mph in about 2.5 seconds (>1g lateral acceleration), and goes into an extremely high angle-of-attack climb to 1000 ft in about 10 seconds (~6000 feet per minute), and the glider releases the cable at about 1500 ft. It’s quite amusing.

An aerotow is exactly what you would expect – a powered airplane tows the glider into the sky, and normally the glider would pull the release and the tow plane takes the cable back. In some emergency situations the tow plane can also release, in which case the glider would have to fly back over the field to drop the cable first, before coming back to land, since it’s difficult to land with a cable attached to the front of the glider. If they both pull release… the cable will fall on some unlucky dude on the ground. Or an unlucky cow. Or something.

On my first day gliding I got to try both an aerotow (to 3000 ft) and a winch. The aerotow is nice because the flight is much longer due to the higher starting altitude, and also because the instructor let me fly part of the tow since I had prior flying experience!

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It’s harder than you think. Well, at least it was harder than I thought it would be.

Flying in a tow is essentially formation flying. If the glider goes too fast, there will be slack in the cable, which is bad because when the slack is removed afterwards, there will be sudden stress on the connection point which may break. If the glider goes too slow (high angle of attack), it will out climb the tow plane thanks to the extremely high lift wings, which is dangerous for the tow plane because it can put the tow plane into a nose dive if it runs out of elevator authority.

We also have to stay out of the tow plane’s prop wash, by either flying above it or below it.

They charge us for the tow by altitude, so we can pull the release any time, and the tow pilot will note down the release altitude, and charge us that amount afterwards.

We pulled the release at 3000 ft, since it gives us a nice long fall to the ground, while not being terribly expensive.

As soon as we pulled the release, the tow pilot did a steep descending turn out of the formation and dived straight at the runway threshold, in the opposite direction of the active runway. That’s quite amusing to watch. That guy has clearly been doing this all day for a very long time and figured that’s the absolute fastest way to get back on the ground.

We did some steep turns, stalls, and landed back at the field in about 25 minutes. The glider has a sink rate of something like 150 ft per minute, and you can actually do a steep 360 turn and only lose something like 200 ft. It’s absurd for someone used to powered airplanes.

The glider I flew (Schleicher ASK 21) has a glide ratio of 34:1 at a Vgs (best glide speed) of about 50 kt, and that’s obviously the biggest difference between a glider and a powered airplane, which typically have glide ratios on the order of 7:1.

It’s almost impossible to land a glider without using spoilers or air brakes, since they would just float forever.

With air brakes, it sinks like a rock just like a powered airplane, but using air brakes is pretty tricky, since they require the use of elevator at the same time to maintain approach speed. It’s called elevator-spoiler coordination. They must be used at the same time, just like ailerons and rudders. Definitely something I have to work on.

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Besides spoilers/air brakes, another major difference between gliders and powered airplanes is the use of rudders. Gliders need much more rudders to coordinate turns thanks to the extra long wings. That said, I didn’t really find it to be a problem. Definitely more rudder than on Diamonds, but only about the same amount as Citabrias (and probably other tail draggers).

Controls are much more sensitive at low speed (50 kt), obviously since this glider is designed to fly at low speeds most of the time, though some competition gliders do go quite fast. On a DA40 for example, at 60 kt you would need pretty much full control movement to make it do anything. Not the case for gliders. I wonder how sensitive the controls will be on a glider in a high speed dive.

The cockpit is also much simpler –

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The major instruments are all the same.

Airspeed indicator is slightly simpler since there are no flaps and no Vx or Vy. Vgs is marked. We really only care about Vgs and Vne for the most part.

One interesting instrument is the variometer. It’s kind of not really the same as vertical speed indicators, in that they do indicate vertical speed, but only as a result of air movement, and not control input. It compensates for control input, so if you just put the glider into a climb by pulling back on the stick, the variometer won’t actually go up.

And the most important instrument is a piece of string taped to the windshield, for turn coordination. Not sure why they don’t use a regular turn coordinator.

I didn’t get to do the landing on this flight, but it’s interesting that we can pretty much just pick anywhere to land on the field, as long as there is grass…

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(Picture from Wikipedia since I forgot to take one)

On the next day, I got to fly a motor glider, the Scheibe Falke SF-25C to practice circuit planning, since that’s probably the hardest part of the conversion from powered airplanes to gliders, since glider circuits are slightly different.

Yes, we actually turned off the engine after takeoff.

We usually start the circuit on the upwind side at about 800 ft, fly a fairly standard downwind and judging glide slope using a strange method, and do a diagonal leg between downwind and base, where we can adjust if too high or too low, then finally landing with speed brakes or spoilers.

I haven’t been flying for about 3 months now, so the first few landings, while definitely survivable, weren’t exactly like butterflies gently planting their feet on the petals of a flower. Need to get my flying skills back!

I am starting to get the hang of glider circuit planning though!

From now on, I’m planning to fly every other week or so, and hopefully get my glider license in a few months. Knowing how to fly an airplane definitely helps a lot, but there’s still quite a bit to learn.

Quite a change to switch to the most basic form of flying after having flown airplanes that cruise at 140 kt with full glass avionics and 2-axis autopilot coupled with nav computer, but I’m loving it!

… my wallet is loving it as well. It doesn’t even want to think about renting a powered airplane in London. Cessna 152s here cost more than G1000 DA40s back in Canada. Crazy. Also doesn’t help that all airports charge landing fees!

Next up: archery and SCUBA diving. Yeah, I’m probably going to fail my degree.