Why waste money, weight, and space on down...or ANY fill for and UQ?

**hutzelbein** · 03-30-2016, 05:10

In order for your idea to work, you would need to sew a lot of fabric pockets to keep the air from circulating (and thereby constantly moving warmth to the colder outer shell). I believe this is what Therm-a-Rest is doing with their NeoAir pads: there is no insulation in the pads, just many air chambers. The question is, is it possible to use the principle for an underquilt? And will it save weight over a down quilt? It definitely won't be as easy to design and make as you imagined it - otherwise somebody would have already done it. You might also want to look into the "Garlington insulator".

**jcdflint** · 03-30-2016, 05:11

Originally Posted by Jeff Myers

Really holding back a smart tail answer to this question right now.

It is not the total amount of air but the frequency of the individually trapped pockets. Heat becomes stored there. Even put a down jacket back on after being too hot. It is still warm. Sure a large air gaps means the heat has to travel farther, but unless we are talking a vacuum sealed chamber , air is not the insulation.

Bubble wrap ..Dude ! :0

**jcdflint** · 03-30-2016, 05:22

Originally Posted by Mystery Oneal

I have been hand sewing my down TQ, I'll try to get some pics up when she's finished. Since it is being hand sewn, I have had lots of time to meditate on the design for my UQ...which i will also be hand sewing...after I finish the winter tarp.

During my meditations I realized that the down in an UQ doesn't really do all that much to improve the efficiency of an UQ. On a TQ it is pushing the 2 layers of fabric apart to maintain the 1-3 inches of trapped airspace, and the trapped air is what is keeping us warm. But, on an UQ we have gravity working for us. In theory, with slight modifications, one could easily make an UQ shell that hangs with a relatively uniform space between the 2 layers of fabric and works just as a down filled one. The only real catch is that the shoulder area might need some help staying at optimal fluff.

My idea was to have the two layers of argon 90 with a 2 inch strip of webbing sewn between them around the perimeter (similar to the way baffles are generally sewn across the middle). Argon might work as the 2 inch strip, but I figure the stiffness will help it keep the 2 layers apart in the corners. Also, I would add a baffle (of any material) down the center (lengthwise) to keep the bottom layer from sagging too much. Everything else would be pretty standard, cinch cords on the head and foot, shock cord along the length for suspension, etc. I have also played around with the idea of having the top bit of fabric a few inches narrower than the lower fabric. The idea is that it would be easier to sew than darts, and should minimize compression (this is something I will mock-up once the rest of my fabric arrives).

For those that have months and years of UQ R&D experience under their belt, I challenge you to give me one good reason why I should put down in my UQ....other than the fact that I'll have 7 oz of the stuff left after I stuff my TQ. Thanks for the feed back.

Not the best Idea... BUT !!! keep your invented mind going.. Always good to do things with your own hands ..

Have fun with this Hammock stuff.. Good day , Jeff P.S Don't let the "NEG" stop your passion ...

**Sunndog** · 03-30-2016, 05:46

There is one thing that needs a mention in this thread

Dude is HAND SEWING an UQ, TQ and tarp!.....that deserves some major respect imo

**hutzelbein** · 03-30-2016, 05:51

Originally Posted by jcdflint

Yupppp... no need to play anymore.. Its all been done...lol

That's not what I said. I only said that the original idea won't work, because it's so simple that somebody would have done it already. Actually, it's very close to the Underquiltprotector-concept - which I use and love. I also said that the basic idea works - but that it's not as easy to implement. I'm all for experimenting. I have done quite a bit of experimenting myself - that's why I know that in 99 out of 100 cases it turns out way more difficult (if not impossible) to achieve the initial goal. If the OP will experiment with fabric air pockets (but way more than he suggested), I would be very interested to read about the results.

**jcdflint** · 03-30-2016, 06:35

Originally Posted by Sunndog

There is one thing that needs a mention in this thread

Dude is HAND SEWING an UQ, TQ and tarp!.....that deserves some major respect imo

Amen...

**jcdflint** · 03-30-2016, 06:36

Originally Posted by hutzelbein

That's not what I said. I only said that the original idea won't work, because it's so simple that somebody would have done it already. Actually, it's very close to the Underquiltprotector-concept - which I use and love. I also said that the basic idea works - but that it's not as easy to implement. I'm all for experimenting. I have done quite a bit of experimenting myself - that's why I know that in 99 out of 100 cases it turns out way more difficult (if not impossible) to achieve the initial goal. If the OP will experiment with fabric air pockets (but way more than he suggested), I would be very interested to read about the results.

Good reply...

**mountainhanger** · 03-30-2016, 06:50

Originally Posted by kev138

Air filled baffles would be inadequate insulation because there is nothing to trap your bodies radiated heat. Down, synthetics, wool, etc., trap the heat you give off and warm up the air in between the fibers ( or feathers ) allowing you to stay warm. An undequilt with no insulation wouldvbe like running the heat in your house with all the windows and doors open.

Mylar ( space blankets ) and sleeping pads work ny trapping your heat because they are impermeable and do not allow the heat to pass through. The dowside being in really cold weather they also trap moisture generated by the temprature difference between your body and the air ( think a cold glass of ice tea on hot day and picture the beads of water. Same principle).

What you describe sounds like a very complicated wind sock. It may block some of the oustide winds on your bottom but it's not going to trap any of your heat. Air is a good thermal conductor but a poor thermal insulator.

But i am no expert, i just read alot. My understanding or attempt to convey it may be imperfect. It may be safe to say that if it were a bang up idea somebody would be doing it, and selling it.

Well said ..... Thank you for this response

**GreatBigDave** · 03-30-2016, 07:06

Originally Posted by Mystery Oneal

... For those that have months and years of UQ R&D experience under their belt, I challenge you to give me one good reason why I should put down in my UQ...

One word: convection.

**Wanderlost** · 03-30-2016, 07:13

The flaw in your logic is that the down functions as a means to keep the heat from transferring through air movement. It acts as a baffle to limit the air movement. Air is a good thermal conductor but it does not insulate well. Your body may warm up that air in the UQ, but any air movement is going to pull that heated air away and replace it with colder air. The down limits that air movement so the warm air stays where it is better.