The paragliding variometer - here's a brief introduction to this wonderful little flight instrument. Perhaps it's more like semi-random waffle, but I guarantee you'll learn something!
Practically all pilots of engine-less aircraft are familiar with variometers, or varios as they are often called. This is because the variometer is essential to getting the most benefit out of the rising air, or lift, you might encounter during a local or cross-country flight.
It's function is to tell you exactly how fast you are rising or sinking relative to the ground.
Although a pilot can feel the surging of the aircraft as it enters thermal lift, it's hard to tell everything that is happening just by 'feel'. Once the aircraft is going up at a more-or-less constant rate, you need a variometer to detect tiny changes in lift strength. This makes it possible, with some practice, to work your way into the middle of the thermal. There are several other kinds of lift, but a paragliding variometer is mostly used for thermal lift. That is, big parcels of rising air that are slightly warmer than the surrounding air.
A bit of trivia. Someone has figured out how to modify a Gameboy Advance SP and turn it into a paragliding variometer! I would imagine you would need some electronics ability or experience to do this successfully. I won't include the link here, it might be gone tomorrow. :-) Just search for it using The Well Known Search Engine Which Starts With G.
A paragliding variometer can have up to three ways of letting you know your vertical speed. Audio sound, digital readout or analog clockface.
Some varios are quite basic, like the simple audio-only vario with nothing but an Off/On switch.
Let's have a quick look at each type in turn.
The audio sound indication. If you are going up faster than a pre-set value, you hear a beep-beep tone which increases in pitch the stronger the lift is. Different models have different sounds. Some of them have a sink-alarm as well, warning you with another sound that you are sinking faster than some pre-set value.
The digital readout. Just a number here, like a digital clock. The number gives an accurate indication of vertical speed, in knots, 100s fpm (feet per minute) or m/s (meters per second). Or, somewhat quaintly to those of us used to the metric system, Miles Per Hour. :-) Mmm maybe not in a modern paragliding variometer, but definitely the case in some older U.S. varios used in sailplanes.
And the analog clockface. Not a real physical clockface any more, these days its a picture on an LCD display. Although you don't get such a precise indication, the 'needle' on the 'dial' gives you an instant impression of how fast you are climbing or sinking. If the needle is horizontal, you are in 'zero sink' meaning that you are maintaining the same altitude. If the needle points up, you have a grin on your face, if it points down, well let's just say you have a few things to think about for a while. Unless you're tucked under a nice cumulus cloud at 3000 m (9000 ft) that is.
The audio-only devices mentioned above are the paragliding variometer of choice for those pilots that really like to keep things pure and simple. Also those who avoid complex technology whenever possible! 'I can center a thermal pretty quick with this, why use anything else?' these guys would say. Also, most audio varios these days seem to take lithium batteries that can give around 6 year's operation for the average pilot!
Looking over all the currently available gear, there seems to be just two basic groups of paragliding variometer used by pilots today. Some ultra-simple audio-only units for the 'simple is best ' crowd at one end, and a number of almost ridiculously complex devices for comp pilots and gadget freaks at the other. :-)
Common to all the devices is modern mankind's unrelenting drive towards miniaturization. I guess one day we'll have voice-command audio varios surgically implanted into our ear-lobes. :-| Holographic GPS displays projected into the air from tiny projectors built into our helmets... Who knows.
It seems the design of a high-end paragliding variometer, such as the Flytech 4030 Race is driven by a small number of top competition pilots who are able to influence the manufacturers with their wish-lists. These guys are so busy in the air that they also demand the utmost in 'ease of use' as well. So at least these devices are becoming easy to use in flight, despite the huge amount of information they can provide.
As you might have gathered, the top-end 'varios' are actually far more than just variometers. More like 'flight management systems' really, packed with features related to speed, time and navigation. And these kinds of instruments continue to pump out information even on the ground. You can upload data collected during a flight onto your PC for later analysis. At least one paragliding variometer will even print barograph traces out for you!
All rather hi-tech compared to the mechanical barograph I used when I took the Alice Springs Gliding Club's Standard Libelle to 13200 ft amsl, to claim my Gold 'C' altitude gain. On a 'blue' day, not a cloud in the sky as I remember. Many years ago now. The trace was etched onto a foil sheet which had been held over a smoky candle, before the barograph was sealed. Afterwards, a nice spray of shellac or similar stuff was applied to make it a permanent record. How times have changed!