Date: Mon, 5 Apr 1993 17:39:38 GMT
From: sasaki@netop3.harvard.edu (Marty Sasaki)
Message-ID: <1993Apr5.173938.11709@das.harvard.edu>
Organization: Harvard University
Subject: Quality of construction, especially the Big Brother


Sam Rouse submitted a few things about construction quality of the Big
Brother. I would like to take exception to much of what he said about
the construction quality.

First, let me say that I agree that the Big Brother is an
exceptionally fine flying kite. I often fly my BB just for the fun of
flying.

     1) Reinforcement weight is kept at a minimum.  Leading edge 
     pockets are made of a double layer of the same fabric as the sail, 
     with small diamonds of heavy dacron around stress areas (barely enough 
     to surround the holes).

Adding full reinforcements or heavier fabric in certain areas won't
add much to the weight of the kite, and will result in a more durable
kite. As an example, 1.5 ounce ripstop leading edge rather than two
layers of .75 ounce fabric will hold up to abrasion better, and won't
add any weight to the kite.

       Seams are simple overlap-and-sew (no folds); 
     this also seems to minimize airflow disruption (though it doesn't look 
     as tidy up close and may not be as strong).  In another airflow 
     preservation measure, bungees at the wingtips are knotted inside of the 
     leading edge pocket.

This has minimal or no effect on the airflow. This was done to make
construction easier and quicker, I'm sure. Bob Childs, who knows more
about airflow on stunt kites than almost anyone, double folds his
seams.

      2) Standoffs are made of the same material as the 
     frame, and fit into closed vinyl caps connected to the spreaders and 
     sail (no protrusion at all in front or back).  Reinforcing where
     the standoff connects to the sail consists of 7 long oval-shaped 
     patches of sail material arranged in a pattern radiating out from 
     the attachment point and folded around the trailing edge, making the 
     area of greatest stress 15 layers thick and distributing the stress 
     over a large area.

I have to admit that this is really slick and very pretty. It looks
like a flower on the sail. Having said that, if you really wanted to
save weight, you could use a much ligher standoff. The reinforcement
is also overkill and adds weight.

       3) Vinyls have a two-part construction - an outer 
     sleeve of thin-walled vinyl (for strength and rigidity) and a softer 
     inner sleeve of some other, sort of oily-feeling material (neoprene?) 
     which has the odd but wonderful characteristic of maintaining a solid 
     grip on the rods while never getting stuck to them (always easy to 
     assemble & disassemble).

This is a very neat construction detail!

      4) Tail of sail is attached to the keel 
     with a velcro system to allow compensating for sail stretch.  

This is a neat feature, and requires a lot of work to sew. A long
enough length of bungee would do the same thing.

     5) No metal anywhere on the kite (nice to not have to dispose 
     of those ridiculous boatanchor swivel clips on the bridle that 
     so many mfgrs are still obsessed with!

I agree here, but be careful about the loop attachment system. A
larkshead is one of the weakest knots around.

       6) Very light framing material is 
     used; very thin-walled.  It seems to be comparable to the
     Beman "Diva" spars used on the Chicago Fire Bees but with 
     even thinner walls. This is the lightest kite I have flown.

Wolfe says that these are Wolfe rods. I suspect that they are Beman
rods. They are a nice compromise of stiffness and weight versus
strength. I did a quick measurement of one of the rods and found that
it was identical in specs to one of the Beman rods.

      7) Finally, 
     and perhaps most important to the performance of the kite, it does 
     not have a flat sail - only when the standoffs have been put in place, 
     making the sail taut and imparting a slight curve to the leading edges, 
     does the kite assume its real shape.  The tautness of the sail also 
     makes it very quiet in flight.  Seams use a wave stitch combined with 
     a straight stitch; the material appears to have been glued prior to 
     stitching.

This is beginning to be old hat, although the Big Brother was one of
the first to have this configuration. Many kites are like this
including the Katana, the Jordan Pro, and the Tracer.

I have very mixed feelings about the construction of the Big Brother.
On one hand, the reinforcements are well placed, and the velcro
adjustment on the tail are nice. On the other hand the seams are
irregular and poorly done, and the trailing edge hem is uneven.

Don't get your Brother wet, or if you do dunk it, remove all tension
from the sail as it dries. I've heard of many Brothers flying very
poorly after they are dunked...
--
Marty Sasaki            Harvard University           Sasaki Kite Fabrications
sasaki@noc.harvard.edu  Network Operations Division  26 Green Street
617-496-4320            10 Ware Street               Jamaica Plain, MA 02130
                        Cambridge, MA 02138-4002     phone/fax: 617-522-8546


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