UKHAS Wiki

UK High Altitude Society

User Tools

Site Tools


guides:how_to_lose_your_flight

How To Lose Your Flight

There are many, many ways to lose a flight, and the aim of this page is to list as many of them as possible, in the hope that new launchers avoid all of the standard pitfalls. Of course, it's possible (and perhaps likely) that new launchers will come up with new and exciting ways of losing a flight, but at least by reading this list you will put some thought into making sure that your flight is one of the successful ones.

Before You Launch

Choice of tracker
  • Rely on a GSM tracker. In the UK, GSM trackers seem to work in about 50% of flights in which they are used. So with one of these (and nothing else) you've got a 50% chance of losing your payload. Even if it does work, you won't get a position until about the time it lands, so you won't be able to get to the area, which is good as it increases the chance of your payload being stolen, or eaten by a combine harvester, before you get there.
  • Rely on a SPOT tracker. It's not quite as unreliable as a GSM tracker, but it's close and has the same disadvantage of not working throughout the flight. As a bonus, the SPOT is expensive and roughly doubles your financial loss if indeed you never recover the payload.

As you intend to lose your payload, you won't use a radio tracker. These, sadly, offer the most reliable option (but you can reduce reliability by not testing - see below) and work throughout the flight (though there are ways to alleviate this - see the section on Tracking below).

Testing
  • Don't bother testing that your tracker works when it crosses a meridian (latitude or longitude).
  • Don't test that it reports the altitude correctly above 32,768 metres and below zero metres. Obviously you can only test this by faking the altitude, but that's such hard work that you may prefer not to bother.
  • Don't test the range. This involves putting your tracker in one place and your receiving equipment in another - for example find a friend to drive off with your tracker in a car whilst you receive and decode the signal at home. Doing so checks many things - transmitter power, quality of the aerials, and sensitivity of your receiver, so avoiding this test gives you 3 different failure modes for the price of one.
  • Don't test how long the tracker works on batteries. The flight batteries (Lithium Energizers) are expensive so you can save money as well as time by not bothering with this test.
  • Don't test that the tracker works when cold. Well, the freezer if full isn't it and you don't want your significant other to drop your tracker on the floor when grabbing a pack of frozen peas. Or perhaps you do …
  • Keep your constructed payload somewhere comfortable where it won't get dropped on the floor or, worse, down the stairs. Just think - dropping it might break something! Much better to wait until the balloon bursts (when the payload may well spin uncontrollably) or when it hits the ground (hopefully at 30mph because you messed up the parachute) and allow it to break just the once.
Payload Construction
  • Use a large container with plenty of space for the contents to fall about (see above).
  • Don't use polystyrene foam, so the landing impact is much harsher on the contents (and, for bonus points, on whatever it hits).
  • If you do use foam, make sure it's that stuff with the metal foil backing. Your payload will be safe but, because the foil blocks the GPS signal, you won't know where it lands.
  • Put all cameras inside cases. GoPro, for example, sell a model specially designed for the purpose. It has “humidity strips” which will absorb moisture from the atmosphere before you launch, and then, at altitude, deposit that moisture as fog on the coldest part of the case which is right in front of the lens, producing an artistic soft-focus effect.
  • Solder the radio aerial on so that, with a bit of luck, it will fall off during descent as the support lines wrap around the spinning payload.
  • Choose a good colour for the payload box. For example, duct-tape grey in winter, or bright yellow if you're hoping to land in a rapeseed field in the summer.
  • Use an RP-SMA plug on the aerial, and an SMA socket on the tracker. This is advanced failure mode, and everything will look OK before launch, but you will notice (with delight) that your tracker's signal disappears within seconds of the launch.
  • Use cheap batteries rather than Lithium Energizers. This includes Duracells Alkaline or anything else that is not a Lithium primary cell. 2 recent flights used this option, on the same day, with 1 successfully lost and the other only found because it had a backup radio tracker using Energizer Lithiums.
  • Don't build the tracker on a PCB or Veroboard, as these are solid and reliable. Instead, use a breadboard, and pretend your taking things seriously by using cardboard and/or duct tape to stop the components from falling out.
Before The Launch
  • Leave everything you can till the last moment. For example, don't bother doing any tracking a day or 2 before your launch day. This gives you a great excuse for not doing any of the testing (see above).
  • Don't check the predictions. Well, Michael Fish said that that hurricane wasn't going to happen, so what do the forecasters know?
  • Ignore the predictions. Same reason as above. Just because the predictions show a landing in the middle of London, they'll be wrong, won't they?
  • Don't create a payload document, saving you the time of seeing if your tracker actually appears in the right place on the map.
  • Don't create a flight document (see launch fails below).
  • If you tracker has a “Remove this before launch” tag, forget to actually remove it. This is much easier if you …
  • Don't have a pre-flight checklist, or if you do then don't have someone whose job is to make sure the items are confirmed and checked off.
  • Don't check that you can receive, decode and upload telemetry from your tracker to the internet.

Launch Fails

  • Don't label your payload with a phone number or email. I mean, when your payload lands at 30mph into someone's greenhouse, you don't want them contacting you, do you?
  • Don't put in enough gas, ensuring that your flight goes a lot further than you expected, perhaps landing in the sea. If it's windy, it's really easy to do this as the wind will lift the balloon and thus mess up your careful neck-lift calculation.
  • Don't bother tracking the flight at the launch site. I mean, you know where it is, so what's the point? Once it's in the air though others in the HAB community will start to track for you, unless …
  • … you don't tell them. Sneaky huh?
  • Or, you could tell people about the flight, but not bother to create a payload document. That makes it more difficult for others to tracker, especially as they won't know the frequency to listen to. Hey, these guys do this as a hobby, why make it easy for them?
  • Celebrate your flight before you even launch, by inviting your team to a nearby pub for a drink or 3. This relaxes all of those pre-flight nerves.
  • Forget to take weighing scales, so that the amount of gas in the balloon is a complete guess. This will hone your chasing skills as you won't have a clue where it's going to land, if it ever does.
  • Use nice dark materials for the payload container and, especially, the parachute as that is usually the easiest thing to spot after landing. If you can manage to land in a rape seed field then yellow is ideal, but if not then just opt for black and try to land at night. Perfect!

Chasing

  • Take your time packing up your kit into the chase car. The longer you take, the further away you will be from the flight when it lands, meaning that you won't get a good final position before it falls below your horizon. You will then have a wider area that the payload may have landed in, increasing your chances of spending the next 4 hours driving around aimlessly while those cheap batteries slowly die.
  • Chase on your own. You may find it a tad difficult to keep the receiver tuned in, and watch the map to see where the payload is, and check the IRC channel for advice, all the time whilst driving, but if not then at least you have insurance. You do, don't you …?
  • Don't take any tracking kit. Right now you're asking “Oh pleeeease, nobody would be that stupid”. Think again; it's happened.
guides/how_to_lose_your_flight.txt · Last modified: 2016/05/10 07:10 by daveake