Originally Posted by John255
This really sounds great! Count me in!
So your hope is if there is enough response RCG we may get a dedicated category for 1.5M and smaller.
May be good to start talking about the launch because that determines needed space. You are lucky to have so many large parks.
The term Zip-Start gets used for Hi-Start but they are different. One supplier of The Zip is Aerofoam. It is 15' rubber, and 25' line and can be used in 100' space.
I don't have any experience with these, but they sound to me like a lot of pull, lot of speed for jets, etc, and some risk. As you know the smaller HL ships can are hard too hold with a lot of pull. In a public park you also don't need the pin becoming a missile.
Sky Bench makes a good mini hi-start, but I don't recommend it any longer because of price and his high shipping cost.
Probably best may be the Dynaflight Up-Start which is 25' 1/8" ID rubber, 100' line with chute for $28 at Tower.
This one needs min 300' launch space.
I'm searching for a source for mandrel formed 3/16" thick wall UV protected tubing.
There's not much to building them. Maybe somebody's wife might start a cottage industry for the chutes. I have a small one that works good. Not a wife, but a chute.
I guess that's enough for now.
I had these videos that I think illustarate the zip start vs hi-start very well.
Hi-start, up-start, zip start or zip cord
To me a Zip start is a short piece of powerful rubber or bungee cord typically used for high powered launches optimized for speed, hence the name Zip. They typically 10-25 feet of elastic with little or no line. They are often used with flying wings where the hook is in the nose. The plane reaches very high speeds on a flat launch, then is taken straight up at high speeds. Pretty exciting.
F3J pilots use them too. The pull is so strong that the pilot literally has to lean into the plane in order to back up and stretch the rubber. These simulate the powerful pull of a two man tow launch. An example is shown in the video. Note the stance of the pilot as he pulls back.
Zip Start Launches
|3D TD (4 min 42 sec)
I think you are talking about short hi-starts or up-starts. These are soft launch devices consisting of about 25 feet of rubber and 75 to 100 feet of line used for launching TD gliders, optimized for altitude rather than speed.