I just finished reading Tad Eareckson's review of my hook-in alarm on his forum.
Here:
http://www.kitestrings.org/post8270.html#p8270He spends a great deal of time ripping my article (from 1992) to pieces. That's okay. Nothing wrong with that. I'm just puzzled why it took so long. At the time I wrote that article, I was exploring electronic ways to reduce the possibility of FTHI, as were other pilots. He quite rightly stresses again and again the process of lifting the glider and feeling the leg loops, what I erroneously called the hang straps. Hang straps, leg loops, it's all part of the harness suspension. Something I have always done without thinking much about. If I couldn't feel the leg loops, I didn't launch. Quite right and the correct practice that has never failed me. Flying a Fledge 2 teaches you to do that because for me, it's damn near impossible to launch a Fledge as it is VERY tail heavy. If you can't feel the leg loops tugging at your legs, crotch, and butt, the glider won't launch because as you start your run, the tail will drop and you will just be dragging a stalled dead glider behind you. You stop dead in your tracks. I always did anyway. Feeling the leg loops, the Fledge is easier to balance as you start your run. Plain and simple. I never installed the hook-in alarm on my Fledge because I knew it wouldn't make any difference, but on my WW, I figured it
might. Also, on the Fledge, you don't hook into a hang strap. There is none, only a bracket and a bolt. It never had a backup strap either.
The practice of lifting my glider and feeling the leg loops has always worked for me, even while flying other gliders. Enough said there.
Had I read
FTHI.pdf by Tad Eareckson, I probably would have never built the device. It was a curiosity to me back then. In all the years I've had it and used it, it actually prevented only one FTHI. In this case, I lifted the glider and the alarm started wailing. I hadn't fully lifted the glider yet to test the leg loops, but I did pause before launching because of the alarm. It could have been that one time I didn't test my straps. Since the sensor was installed in the backup strap, I set the glider down and hooked into the backup and missed the main. I lifted the glider, felt the leg loops, then performed a successful launch. The glider was a WW Sport 150, much easier to launch than a Fledge. Easier to pickup and launch even when not hooked in.
Also, at the time, it was common to have backup straps and I can't remember why, other than maybe there was hang strap failures leading up to folks adding multiple straps and extra carabiners. I remember when there were carabiner failures.
Anyway, I'm posting this because others have tried to design similar devices and they might like to know a bit more about it's history and whether it was a failure or a success. After reading Tad's essay, I'm more inclined to remove the device and the extra hang strap. The device continues to work, but it does add complexity to the glider.