I agree about the alpine environment, it beats 33f and rain in my opinion too. I would be curious about how much weight you have in your sled? One mountaineer I spoke with gave me figures of 75lbs in the sled and 75lbs on his back, I saw in another thread here on PS about the woman who crossed the Antarctica had 187lbs in her sled. That brings up why we were contacted in the first place, an inquiry about weight reduction and whether or not there might be a better way of doing things.
One model I like is the "5 mechanisms of heat loss".
1) Conduction, warmth being lost due to contact. Warmth transmitted through materials into a colder object you are in contact with.
2) Convection, air movement causing warmth to be pulled away from you as it moves around you ( wind, air movement due to the environment ie. up/down valley flows, on/off shore air movements, etc...).
3) Radiation, warm air radiating up and away from you into space.
4) Perspiration, sweating ( over heating or natural cooling). Moist air conducts more rapidly than dry air enabling greater heat loss reducing efficiency of insulation and other materials.
5) Respiration, warmth leaving via breath. This can also reduce efficiency of insulation and other materials if not properly vented, typically.
Without arguing about the viability of modern equipment like sleeping bags and tents, perhaps there are better ways of doing things? Perhaps weight can be reduced by looking at the problems in new ways? Nor would I try to argue old school vs new school or that equipment can substitute for skill sets. Simply looking at how modern materials and new design can improve on the weaknesses of existing gear.
One thing mentioned above is that a snow cave ( and a well built shelter ) work very well at protecting people from very cold exterior conditions. This is done by the efficient insulation the snow provides and controlled ventilation both of which essentially create a separated air layer just as a parka and jacket do. So creating those separated air layers are very important and using gear you already have can help reduce weight. The sleeping bag has a few weaknesses, like compression of insulation on the bottom and if down , moisture degrades it's insulating capabilities over time. Another problem can be overheating, a modular system can help extend the functional temperature ranges of a system, like the modular 3 piece military sleeping bag (2) and Gore- Tex bivy (1).
Looking at these issues with an eye to reducing weight and improve efficiencies we are trying to simplify the pieces, improve the material efficiencies, incorporate and combine with existing gear, make the pieces modular and maximize design efficiencies. Recently we were invited to a military cold weather and mountaineering symposium where we got to kick around the pieces we are working on in a real world environment and get some good one on one with end users. The results are encouraging as weights were reduced, materials and design has mitigated some of the traditional problems. Plus it was great to spend time with some of you and other military mountaineers!!
Posted are some images and please PM me with any questions. My hopes are that this thread facilitates a discussion about insights into experience and needs so it might be useful to our soldiers. Thanks Group One Equipment...