new cut, dual differential

[te-wa]

i have tested a prototype with differential fabric on the long side, at 2" per.

so now, the top layer on a Freeze is not only 6" wider than the bottom across the width of the uq, but also it is now 2" longer, along the length.

i have noticed this does two things.. first, it forces the uq into a very slight curve, about how you would lay in your hammock.
second, it allows more loft in the baffles, with almost no noticable compression of the down*

im considering offering this as standard or as an option with the quilts containing overfill. id like to see what the customer thinks as well. let me hear your thoughts!

*down has been tested to show that even with a 50% compression, it retains the same warmth.

[jackleberry]

This is the way I've made my (currently only half-filled, awaiting more down) DIY underquilt, loosely based on Shevy77's description. Due to some measurement errors, I ended up with a few inches more differential and less baffle than I had intended. The length differential is 5-6 inches. The result is very puffy looking. I won't be able to tell how well it fits until I snag some more (vintage) down.

[JerryW]

...the top layer on a Freeze is not only 6" wider than the bottom across the width of the uq, but also it is now 2" longer, along the length.

This makes perfect sense to me, and is how I made my down underquilts.

*down has been tested to show that even with a 50% compression, it retains the same warmth.

This is a very comforting statement. Where did you find out about it?


Jerry

[jackleberry]

This makes perfect sense to me, and is how I made my down underquilts.




This is a very comforting statement. Where did you find out about it?


Jerry

I think the quote is from some testing done for the military... I can't seem to find a reference to the results... IIRC the real meaning is that you can overstuff by 100% before you start to loose insulation effectiveness, not that you can compress a quilt 50% and still have the same warmth as you would uncompressed.

[te-wa]

I think the quote is from some testing done for the military... I can't seem to find a reference to the results... IIRC the real meaning is that you can overstuff by 100% before you start to loose insulation effectiveness, not that you can compress a quilt 50% and still have the same warmth as you would uncompressed.

i do believe that the statement said just that... you can squish down to 50% of its full loft before it loses thermal efficiency...
and, i cannot find that reference either but i do remember this: it was posted at BPL by our very own Jack Teir.

I wonder if Jacks' remember that info..

[jackleberry]

i do believe that the statement said just that... you can squish down to 50% of its full loft before it loses thermal efficiency...
and, i cannot find that reference either but i do remember this: it was posted at BPL by our very own Jack Teir.

I wonder if Jacks' remember that info..

Well, given that some fairly extensive searching on the matter turns up nothing in the way of references (not even in the form of marketting claims by the big sleeping bag manufacturers), I would say that this statement currently has the status of myth.

The way you interpret the statement would appear to violate the principle of loft, which would allow one to make a bag/quilt twice as warm for a given loft value by stuffing it with 200% as much down as would normally be required given the fill-power.

I personally believe that most of the claims people make about the added warmth of overstuffing are a result of A) psyhological factors B) increased down pressure resulting in decreased lofting time [most bags recommend 3-4 hours to reach full loft!] and C) crude volumetric calculations made my manufacturers resulting in UNDERSTUFF being the standard, with the added "overstuff" merely bringing the quilt closer to the correct fill level.

[te-wa]

thats good stuff, Jackleberry..
but regardless of mythical status and what not, the new dual differential cut of the te-wa's allows for fuller loft, making the compression of said loft less a concern.

end result: warmer quilt

[jackleberry]

thats good stuff, Jackleberry..
but regardless of mythical status and what not, the new dual differential cut of the te-wa's allows for fuller loft, making the compression of said loft less a concern.

end result: warmer quilt

I've been thinking about that too... Since the baffles run lengthwise, it would seem that any restriction at the ends would cause the down to migrate toward the middle--resulting in less loft at the ends, but also less down (so the down would not really be compressed a lot locally, but instead compressed a little throughout the entire baffle. It's possible that a tapered thickness like this might be somewhat desirable as the parts of your body (or just empty space in the hammock) being covered by these sections of quilt may require less insulation (if, for instance, it happens to overlap the coverage of the footbox of your topquilt). In this case the down would be better used insulating the users core (which is, I think, the basic design principle behind the fractional length underquilts).

Given the complexity involved, I think it would probably be quite difficult to put a number on what influence the edge design (tapered, ballooned, or box-end) might have on the overall temperature rating as perceived by the user. However, with the price of goose down being what it is, there is a compelling incentive to optimize its use...

[te-wa]

true that.

at the gathered ends of my quilt, it differs on lay, hammock design, and user size.
near the knee end, my pad overlaps the quilt. at the head end, im wearing a blackrock or similar hat. so, yes i think its nice that the quilt may shift down towards the core. i find my feet need much less insulation than my torso. thanks for your insights!

[Wags]

do you have pictures of this said prototype? b/c if you don't, i don't believe you...