Mr. Booth, Mr. Galloway. Chris. Dan

[SkyMissy 0]

HOLY SH!#!!
That's a freakin "no shit, there I was" story! Are you all recovered now?
I'm not the man they think I am at home, no;
I'm a rocket man.
Sky World

[cobaltdan 0]

been off line for a while and playing catch up.
we have not done any testing on mismatched 2 canopies out.
what i have read agrees with jlb post.
i am not sure what to say, i also chose to fly a highly loaded main and as part of the equasion a highly loaded reserve. i am confident in my choice of reserve size with respect to openings and piloted landing. an unconsious landing under such a small reserve is risky, but then again as jlb pointed out given so many variables it is risky under any size. my personal feeling is that when jumping a highly loaded main you are accepting certain risks, those risks extend beyond just flying that main. remember its not a parachute, it is a parachute system.
sincerely,
dan

[prost 0]

I don't think there is a clear answer to this quesstion. Each route has its own risks. I think each person needs to think about which risks they are willing to take and chose for themselves. I fly the big reserve with my small canopy but I will not tell anyone they are wrong for flying a small reserve because I know it is just a different set of risks. The only other choice is to upsize your main.
William

[diverds 0]

I am attaching another email string between myself and John LeBlanc. This is my reply to his first email (see above) and his return email too me which I just received.
------------------------------------------------------------------------------------------
-----Original Message-----
From: Dave Schwartz [mailto:diverds01@yahoo.com]
Sent: Wednesday, March 20, 2002 8:22 PM
To: John LeBlanc
Subject: RE: Reserve/Main Sizes
Mr. LeBlanc,
Thank you so much for you timely and very informative
response. I am hearing essentially the same thing
from you that I was told by the folks at The Relative
Workshop. One of my concerns with a smaller reserve
is that of damage in a terminal deployment. Am I to
understand that with a PD reserve this should not be
on my "concern list"? Can you give me any insight
into the reports on the failed MicroRaven Reserves
that I have read about over the last couple of years?
My understanding is that they were being overloaded
and that this is what led to the failures. Am I to
understand that I would not be overloading a PD 126
with an exit weight of 250 lbs? As for your statement
about my choice of main not being as conservative as
my choice in reserve...well, you have a point. The
fact is that I love flying my main and I feel
comfortable with landing it in just about any
situation. My concerns with a smaller reserve are: 1.
I am now under a non-crossbraced, f-111 canopy at a
wing loading of almost 2.0 and 2, I have read these
reports of reserves being damaged at high wing
loadings. If it is safer for me to jump a smaller
reserve that is matched more to my main then I am all
about doing that. I just want to know that I am not
overloading it, and that I can land it safely at that
wing loading. What do you think?
----------------------------------------------------------------------------------------
Hi Dave,
As far as the crossbracing is concerned, structurally,
a crossbraced canopy is very inflexible, so it
generates a lot of force on a quick opening. It can be
brutal! So even though the structure is solid, it is not
necessarily overbuilt as far as a quick opening is
concerned. AS far as the aerodynamic efficiency of the cross
bracing, a great deal of hype has been generated about
all the technical reasons for the superiority of cross
bracing. As PD is the original inventor of cross
bracing, I can tell you that the biggest reason that these
canopies fly so well has to do with the refinements
possible with the airfoil, and not the crossbracing
itself. Jump a modern small PD nine cell ZP canopy such as
a Vengeance or a Sabre2, and will will be surprised at
how well they land (not that you would necessarily
want to go back that direction for your own canopy.)There
will be far less excess energy available on our small
PD reserves than on a modern ZP cross braced canopy,
but there is plenty available nonetheless.
As far as concern about blowing up a smaller reserve,
I want to make it clear that it is not that you
shouldn't be concerned, but that your concerns should be
focused on the real culprit. Our reserves are designed
with more reinforcing than the Raven series, and field
reports all indicate that the PD reserve opens with
less shock load. As for the Ravens that sustained damage,
of course they were overloaded, but not necessarily by
the suspended weight alone. The real overloading was
that they sustained a shock overload due to excessive
forces being generated on opening. This could have been
done at a light loading, if the opening was explosive
enough. It may sound like sumantics, but it is not. If
you control opening forces and distribute those forces
though the system, you are successful.
As for our reserve canopies, our design produces less
shock force on the smaller (126) canopy than on the
bigger ones. There is less surface area out there in the
breeze at any point in the opening, so it generates
less force. (This is an aerodynamic simplification, but
it holds true on our reserves.) Also, the smaller area
still has the same number of suspension lines, the
same number of reinforcement tapes in the same location.
If you think of a big canopy, the same number of line
attachments are spread out farther apart, so each
attachment has to hold the load generated over a larger
surface area. This is one reason why our larger canopies
have heavier reinforcing tapes. It is not because they
are designed to carry more weight, but that the
structure has to carry more load surface for each line
attachment point. They also generate more force at the same
suspended weight, thus need a stronger structure to
safely handle those loads.
As far as PD is concerned, a far more dangerous issue
is that of airspeed. The loads sustained increase only
slightly with increasing suspended weight, but when
you increase airspeed, the loads increase exponentially,
and that is only when things go well! I don't mean to
scare you, but it is important to understand this. The
high speed head down crowd should be very careful
about keeping their stuff closed when going fast, because
it is possible to destroy your harness and skydive
right out of it if you are going fast in a head down
while opening. The deployment systems used on sport rigs
are designed to work very well in a very low speed
cutaway situation, and acceptably well in a slightly
faster than terminal situation. It is a difficult design
challenge, but the emphasis historically has been on the
slow speed situation. Now we have people going faster,
and we are seeing that it is very difficult to keep
the deployment under control in a consistent manner
using the typical sport setup. As you go faster, the odds
of having a problem go up, so slow down!
So bottom line is that, at about 235-240 pounds out
the door, I have a 126 in my rig for small canopies, and
I feel as safe (structurally) with that as I do with
my other work rig that has a 160 in it. I land them
both fine. As for putting the 126 down in a tight area, I
am willing to do a fast approach with my feet in the
tips of the trees, to keep the most of what little
runway I have in front of me. I am also willing to stay
current at straight in approaches on everything I jump.
(This is a big thing for most pilots of little
canopies. You should get nice little swoop on a straight in
with no front risers, even on sub 100 footers.) When I
travel away from my home DZ, I am very cautious about
who I jump with, and what I am jumping. I put more
square footage over my head, in both my main and reserve.
This is purely for the greater options it gives me
when I am in less familiar areas.
Once again, I suggest you try a PD reserve demo, and
try it yourself. A 143 or 160 would be a good first
try, with a full glide approach and a good flare. Then
you can decide for yourself if the 126 is worth giving a
try.
I hope this helps!
John LeBlanc
-Dave
"Gas...Undercarriage...Mixture...Prop...Beer"