From: Bill Brown
Date: Tue, 21 Mar 2023 13:17:37 PDT
I use either the 4mm (5/32") polystyrene tube or the 4.8 mm (3/16") polystyrene tube to inflate the Yokohama balloons. These are Evergreen Scale Models # 225 or 226 available from Amazon or eBay. The polystyrene tube does not stick to the internal valve material but I wouldn't recommend using the 5.5mm (7/32") (model 227) tube as that would be too big and could mess up the internal valve since it could drag it back out as you withdraw the tube.
- Bill WB8ELK
Kapton tape (1mm) has been successfully used to seal balloons. It is better than the heavy-duty packing tape recommended in the video. Another alternative that has been used successfully is Tyvek.
Re: Orbs 32" Balloon Foil Color #1ststupidquestion
From: Bill Brown
Date: Wed, 22 Mar 2023 14:34:33 PDT
Clear is best...silver and white will work, gold and red will absorb too much heat and likely burst. We've done test with all of those colors.
- Bill WB8ELK
Re: Yokohama stretch questions
From: Steve G8KHW / AJ4XE
Date: Fri, 24 Mar 2023 02:18:33 PDT
Ground stretching of some form is certainly needed in order to fly higher and avoid weather. I don't think there is one right way to stretch - there are just ways that have worked. Advice ranges from specifics about humidity, pressures and measuring techniques to Mikael's simple " 0.450psi for one hour" (its difficult to argue with a year in the air).
Steve
K9YO -- Yokohama recommends a high humidity when filling balloons. However what is good for weddings is not necessarily good for pico balloons. It is a fact that moisture will weaken the strength of the balloon material. There was a post that mentioned that the moisture will form a hydrogen bond with the material and may not evaporate. This is not an exact science. As the post above notes a balloon was up for one year stretched without additional moisture. Our club has had a balloon fly around Antartica for several months stretched dry over a 3 hr period to the magic 100 inch diameter. I have also had successful flights stretching dry. All that being said, many people have had success with stretching with higher humidity.
Lots of good info here. I often launch by myself. 10m WSPR is a lot easier for a single person than 20m but can be done. 15m is a good compromise as well. I launch in a grassy yard with no tarp since I like to release some small party balloons as sounding balloons to figure out the best place to launch so I can readjust the launch area. One key thing to note is that I usually put an inch or two of #26 gauge hookup wire on each end of the magnet wire and solder that hookup wire to the tracker...I also cover the solder joint of the hookup wire to the magnet wire with Kapton tape or very small heatshrink. If you solder magnet wire directly to the tracker board there is a high probability of it snapping off at liftoff. You could cover the solder joint with epoxy or contact cement instead of the hookup wires but I think the small added weight of hookup wire is worth it as I've never had a problem using the hookup wire method. I tape the top antenna wire every foot with 1/8" wide Kapton tape to 15 lb braided fishing line. I often do the same to the bottom antenna wire if it is going to be a windy liftoff and there is a chance some stress will be on the bottom antenna wire at liftoff. I tie the fishing line to the tracker such that there is some slack in the magnet wire/hookup wire combo so that all of the weight is on the fishing line. I use 34 gauge magnet wire typically. Keep in mind that at altitude the resonant length of the antenna wire will not be 468/Fmhz used for installations near the ground. It will be something between ground level and free space (492/F). I typically use 483/Fmhz and that seems to work out pretty well. For example, for today's flight W4CQD on 10m WSPR (W4CQD-4 on APRS.FI and amateur.sondehub.org), I used 103 inches up and down and saw some great signal reports. Of course, 10m is really hot now that we are Solar Max.
I make a loop of fishing line/magnet wire at the very end of the top antenna wire and cover the knot with a small piece of Kapton. I then attach a 3' length of braided fishing line to the balloon with a #12 or #14 fishing swivel at the end, I use 1" strips of Kapton to cover where the fishing line ties to the balloon neck. One strip to cover the fill port, poke an 1/8" hole with a hole punch, tie the fishing line to the balloon neck through the hole, then put another piece of 1" wide Kapton over the tie point. The fishing swivel hooks to the loop at the top antenna wire just before liftoff.
I have launched in 20 knot winds but definitely don't recommend that unless you have a 1000 foot concrete runway for it to travel down with no nearby trees or power lines. I did this from a small airport in Indiana and it took almost the whole length of that runway. Try to launch under 5 knot winds with reasonably clear skies. Also check the nearby weather out to about 100 miles downrange to make sure you won't hit any bad weather before it reaches float altitude. Figure it will take about a minute to reach an altitude clear of trees and power lines (1 m/s for a minute to reach 60m altitude) . Also know that in any kind of wind there can be downdrafts...if it is a hot day, try to have it fly over a blacktop parking lot as that will produce an updraft. Figure the distance traveled for one minute based on the current surface winds and that will give you an idea how far away the trees and power lines need to be from you.
You will need to do the pressure test before launch on a Yokohama or similar type of balloon.. I bought an inexpensive digital manometer from Amazon (RisePro but similar ones are available). I use a 60-gallon aquarium pump but also use a Craftman tire inflator (about $70) that has a nice vacuum port on it for rapid deflation when you are done. I usually let it slowly inflate with the aquarium pump over the course of a few hours and finish it up with the tire inflator. 0.45 PSI is what I suggest to test the Yokohama balloons....but the new PartyWoo can handle upwards of 0.65 PSI. As to the SBS-13, they will perform better/higher if you stretch them too...but keep it under 0.2 PSI during testing. You can fly the SBS-13 without pressure testing but I would keep the free lift around 5 grams if you do that. You can go up to 8 or 10 grams if it is pressure tested. All of the above balloon will stay aloft longer if you use a heat sealer on the inflation port. Either that or some glue but the heat seal if preferable.
I have a new batch of Yokohama balloons and I have seen failures at 6.5 grams free lift. I would suggest going with 5 grams free lift on the Yokohama and about 6 grams on the PartyWoo 50" (it's not really 50" but probably about 33 to 34 inches diameter after stretching).
- Bill WB8ELK