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guides:chasing_your_flight

Successful Payload Recovery

This guide aims to help make sure you successfully recover your payload after its flight. It's very easy, on your first flight, to concentrate on getting the tracker and payload made but to forget about how you're going to chase and find it.

Before You Launch

There are things you can do to improve your chances of a successful recovery:

Test the tracker
  • Don't assume that just because it shows where your home is on the map that it will still give an accurate position in the air. Run through a sample flight.
  • Test that it works across meridians.
  • If it's a ublox, make sure you're putting it into flight mode.
  • Test that it reports the altitude correctly above 32,768 metres and below zero metres.
  • Test how long it runs on fresh batteries. This needs to be comfortably longer than the flight time. Minimum should be the flight (say 3 hours) plus 2 hours messing about before launch, and 2 hours after it lands. If you fly with less than this you need to be on the ball when chasing.
  • Test that it works when cold. Minimum test would be in a freezer, but better if you can override the thermostat or put the freezer in “Turbo” mode. Or use a container of dry ice.
  • Test that the constructed payload is robust enough for flight and landing. Watch any youtube burst video to see how violent the initial descent can be. Also the landing might be onto concrete at 10m/s. Will your payload survive being thrown down the stairs or dropped out of an upstairs window?
Construction Tips
  • Design the payload container carefully to ensure that everything is prevented from flying about.
  • Use enough foam insulation to protect from a heavy landing and from the cold.
  • Make sure there's no easy path for cold air to enter, especially around the radio transmitter.
  • Consider giving the radio transmitter its own insulation to stop it from drifting (a drifting radio signal is a pain to track)
  • Construct the radio aerial so that it can't fall apart and that it's protected from being broken when landing.
  • Make sure that payload is going to be easy to spot. Bright colours perhaps contrasting are good. Same goes for the parachute.
  • Think about including a buzzer. Especially useful for tree landings and field landings in the Summer when crops are high. Sometimes you can be meters away yet it takes a long time to find the payload.
Other Tips
  • For a first launch, consider borrowing a known-good tracker from someone else, and adding it to your payload train (i.e. attach it in the line, a few metres above or below your tracker).
  • Or make a simple low-power radio beacon (one that just switches on and off every second or so) and attach that - even if your main tracker fails completely you could use direction-finding techniques to locate your flight.
  • Hone your tracking skills by tracking other people's flights. Don't make your own flight the first one you track yourself!

Setting Up Your Chase Car

A well stocked chase car will make the chase a lot less stressful. Technology has a habit of going wrong during the chase - e.g. phone batteries going flat, 3G dropping out, computers crashing, 3G SIM card running out of credit (I've had all of those plus others). So, if you have spare items (laptops, batteries, audio leads etc etc) take them just in case. On my longest chase (following a foil balloon) just about everything in the car failed at some point during the chase.

  • Make sure you have a working 3G setup. e.g. a 3G dongle on a laptop, or a MiFi type device (3G WiFi Access Point) or (last resort) mobile phone set up for WiFi tethering.
  • Consider having the 3G dongle on the car roof, or using a 3G magmount aerial, for a better signal and fewer dropouts.
  • If you use a phone for tethering, make sure you have a car phone charger and/or a spare fully charged battery. Also take a spare phone. 3G + GPS + WiFi will drain your phone battery before the chase is over.
  • This may sound obvious, but take a suitable SSB UHF radio with you. If you don't you might as well stay at home.
  • Also take a magmount aerial for the roof and a yagi. Check that the radio will have enough battery power for the preparation and chase, and if not take spare batteries and/or a car charger (or use an inverter (12v → 240v) and your regular laptop power adapter - usually cheaper than a car laptop charger).
  • Take a laptop or netbook or tablet set up with the latest dl-fldigi for decoding, plus audio lead. if this isn't the same kit you tested with then test it first! Also, take a car charger to keep that laptop running.
  • Make sure you have an IRC client installed and set up so you can keep in touch with the tracking network. After your own tracking kit they are your best resource!
  • Remember to pack boots, a real paper map (for when all else fails), a telescopic pole / fishing rod and other implements for tree recoveries. If it might be dark when you get to the landing spot, take some good torches (and make sure they're charged up!)

Launching

  • Remember to attach waterproof labels with your phone number and maybe email and postal addresses. Put one on the outside of the payload so it can be seen, and another inside where it can't be lost.
  • If you have a camera in the payload, make the first photograph one of your label!
  • Get that fill right! If it's windy, wait for the wind to stop before measuring the neck lift. if in doubt, add extra Stirks!
  • Check that the aerial is properly attached to the payload. Confirm that by measuring with a meter between the transmitter pin and the end of the aerial, and between transmitter ground and the ground plane.
  • Get online and check that your payload has appeared on the map.
  • Make sure the chase car has appeared on the map
  • Get on the IRC chatroom and tell people when you're going to launch, and what dial frequency you have, so they can get tuned in and help with the tracking.
  • If it might be dark before you get to the payload, put some hi-viz reflective tape on each surface. you don't need much and it's not expensive. With the tape, and a good torch, it's actually easier to spot a payload at night than in the day.

Chasing

  • Unless you're lucky enough to have a landing spot within a few miles of the launch site, you will need to get packed up quickly. Consider doing that before launch - have someone hold the balloon while everyone else puts the kit away in the chase car(s).
  • Have one passenger whose job it is to keep the tracking running, to keep an eye on where the flight is going and the expected landing spot, and to stay on the IRC channel to keep everyone else informed and to ask for and get advice on where to go etc.
  • Each chase is different, but in general it's best to basically follow the balloon and to find somewhere to wait, roughly where the expected burst point is, where you are close to the major roads in the area, until the balloon has burst. A junction between the 2 major roads in the area is ideal as then you can go quickly in any of 4 directions once the balloon has burst and you have a fairly good idea where the balloon will land.
  • Don't make the mistake of committing yourself too early - i.e. driving down some tiny twisty roads to the predicted landing spot when you can just wait on a more major road. It's easy to find yourself 1 mile from the landing spot but 3 miles and 10 minutes away by road.
  • If the flight is down and you don't have a signal, drive to a road near the expected landing spot or the last known position. Once you're within about a mile you should hear the signal come back.
  • Once you can hear the signal, try to get it decoded. if you can't get a full sentence either stop and get the Yagi out, or drive towards the signal as it gets stronger.
  • When you have that final position, tap it into your Sat Nav and follow that. Or use mapping on your PC.
  • Get as close as you can by road. If you can't see the payload use a handheld GPS, or a smartphone with GPS mapping - several offline mapping programs are available so you are still covered without 3G, or a smartphone with a direction-finding program such as “Ham GPS”. Take a radio with you (a scanner is ideal) and the Yagi.
  • Note that the predictor does not know the ground height. Predictions will tend to be a few 100m further along than the actual landing. Never rely on a prediction to find the exact payload location, its easy enough to walk past a payload when you know where it is, knowing the location to 100m is as good as lost without a radio
guides/chasing_your_flight.txt · Last modified: 2013/07/22 09:20 by daveake