First, I had to calculate the parachute’s parameters, I mean the canopy’s form and size.I chose a dome-shaped canopy. You won’t have difficulty seaming it together, and it will be fairly effective. All you need to do is cut out 14 pieces like the ones shown in the picture below and quilt them.However, we must know the length and the width of a piece. It depends on the canopy’s size and is calculated by the following formula:

where m is the weight of a jettisoned object, g = 9.81m/s; Cx is the aerodynamics finesse (for dome-shaped canopies, Cx = 1.3); p is the air density. At +20°C air density is 1.2 kg/m; v is the speed of descent.Now let’s try to figure out the appropriate speed of descent. To fine-tune it, I’m going to use my first trainer plane – a ceiling-tile LM-07 (it’s gone through hell and high water since it was built, and now the only divine parts of it are the empennage and the wing. The rest of it has been replaced repeatedly). Its flight weight is 1.2kg. However, to be on the safe side, there should be 1.5kg (considering the weight of the parachute, onboard cams, etc.)Now the speed of descent. Generally, the plane should survive a fall from 1m on the landing gear. Calculated by the formula

the maximal speed of descent is approximately 4.42, and we’re going to scale it down to 4.4m/s.Now that we have used all values, we have a canopy size of 0,98m, which we will definitely round up to 1m. By the way, this is the size of the dome's base, not of the entire canopy.Now let’s calculate the length of the pattern. The perimeter of circle is calculated by the following formula:

The perimeter is 3.54m. As long as we have 14 pieces, each one should be 25.3cm wide. The height of the pattern is 0.9m.Well, how big a piece of fabric do we need? As far as I calculated, it would be 3x1.2m.A 3x1.5m piece was available at the local store. Make a paper printout, cut out a template and line off the fabric. First we refer to the formula above and later, given that the pieces of fabric are a little wider, use a different scheme. Eventually, I had 15 pieces instead of 14, which meant that the canopy would be a little bigger I should say that at that point I should have noted that irregular number of lines could have posed difficulties, but things finally turned out even better!Cut it out.Then I quilted it. I used a compact, convenient and, I dare say, hobbyist-oriented sewing machine. The only flaw – the self-loosening seam – can be fixed by blocking it at both ends. This makes the seam very strong.I pieced it together in sections – first in twos, then I’d put the twos together to make fours, and so on.Next thing we do is fix lines. There are no photos, but all you need to do is attach strong threads, which have the same length. Attach them where the seam ends.The whole thing resulted in an impressive canopy. However, I did realize that I had chosen a wrong type of fabric, since it was too heavyweight (the shop assistant had told me that was the lightest-weight of all available ones at the moment. Well… I’ll look for lighter fabric a bit later). The whole parachute weighed 300g. Well… quite the margin, which I made in the beginning. What I really didn’t like was that the parachute seemed too big even in packed form.I spent long hours trying to figure out how to release it. That was not about dumping weight from the airplane, because that weight would be the airplane itself. Finally I decided to attach the parachute to the belly, and it was supposed to come off under the action of gravity and counterflux. The plane was supposed to turn over after canopy deployment and to land upside down.I made 3 line groups, each containing 5 lines (that was when 15 made right!); two fastened over outer wing panels and one – over the tailboom. First time we followed the packing method applicable for true large parachutes, which we had looked up in the Internet. The test showed that the method was fairly effective, but too labor-intensive. Therefore, we went over to a simpler and faster packing technique.The tape should come off during separation. Choose mounting points on the fuselage in such a way as to place them symmetrically around the gravity center. For example, I have two on the front edges of the panels (placed at one third of the panel’s length from the fuselage) and one on the fuselage at a little shorter distance. First, I’d try to mount it by the tail strut, but the line would get too slack and the canopy would collapse on that side.I had borrowed the idea from Sergey Alexeev from Krasnodar. I didn’t use pull rods though. I just attached a servo with an arm to the body. Once I turned the transmitter knob, the rubber band would come off from the servo arm and release the parachute.Well, why cover the parachute with paper (as shown in the parachute packing video)? First I thought that it would improve its aerodynamics. On a hot day the rubber band would stick to fabric and pull the parachute sideways, which would inevitably result in the parachute getting caught on the wing mount pins or completely failing to deploy, because the rubber held tight. It wouldn’t stick to paper – the rubber would slip off letting the parachute go right down and backwards.. As I went through parachute packing and strapping drills, I made about half a dozen test launches. Although not all of them went perfectly, I ended up with a clockwork system.Here are onboard and ground cam videos of three successful tests (honest, during the first one the lines twisted but, happily, untwisted before landing). The onboard cam was looking down at an angle.FlawsFirst: the parachute turned out to be too big and heavy. Using lightweight fabric is a solution. Second, in order for the parachute release system to work properly, you should keep your plane horizontal during flight. However, I think I should have tried other positions as well. Anyway, what I did was quite enough for ‘messing’ with the plane rescue system:)Thanks for reading and watching :)