Richard Thorp <rthorp>
writes:

I have been laid low with sinusitis for the past week – so thought
I would do a release force test on my barrel release – something that I have
been wanting to do for a while:

I use the top black one in the picture - I forget the source of it but it is a
thin wall aluminum barrel 3/4in inside diameter with a stainless steel curved
pin. The tension is limited by a single loop of the fishing line I have used as
a weaklink since Hempstead. I do not have a good way of measuring forces – I
used a lever and baggage scale. To the best I can determine the weaklink was
failing around the 200lbf mark, so all the tests done were probably between
150lbf and 200lbf

Anyway. At this “high” load of 150 – 200lbf, the top black release takes a VERY
VERY strong pull to open it. It always opened, but the release force is MUCH
higher than I am comfortable with. You have to be sure to grip it properly when
releasing. I can really see how a first attempt could potentially fail. It could
be helped with a larger diameter ring around it so that if you slide your hand
down the line there is a better shoulder to pull against.

I have another barrel release – the lower one with the red line. This I made
myself with thick wall Al tube 3/8in inside diameter and a straight parachute
pin. This is very similar in geometry to the ‘Getof’ release I have seen around
– and is a design I like. The combination of the straight pin that has a better
mechanical advantage and the smaller tube means the release force is much
smoother and very easy – 2 fingers can easily operate it.

So – what is the conclusion?. Well this is a personal question of risk
tolerance, but for me I feel the 3/4in design is very marginal. I am now not
wanting to use it as my primary and have to fight with one hand off the bar to
effect a release. I also can see very little sense in using it as a secondary
release – secondary releases will be used under high stress situations and often
with an unpracticed hand with the release in an awkward position. For approx $10
and 10 minutes work I can make up a much better alternative.

Just food for thought.

Personally, with hundreds of launches, I have not had any problem
with the smaller blue version of the curved pin barrel release. Thanks to Larry
Bunner.