Welcome! Ultralight backpacking is my passion, and keeping up on new technologies, gear, and techniques relevant to UL backpacking is what floats my boat. I'm always looking for the lightest, most functional gear to improve a lightweight or ultralight backpacking kit, and report my impressions and field testing results here. For hikers wanting to keep up on the latest and greatest ultralight backpacking gear, this is a good place to hang out. Also, there is a lot of information here (and on our informational website Southwest Ultralight Backpacking) on useful techniques and backcountry etiquette -- food for thought for hikers wanting to lighten their load and their impacts.

My goal for Ultralight Insights is to understand, test, and report on new technologies and gear of interest to lightweight and ultralight backpackers. It's a passion after all, so we just plain enjoy talking about it. I hope readers will add their own wisdom and comments, respond to my questions, ask their own questions, and correct me if I get something wrong. Happy hiking! Will

Saturday, September 13, 2014

GEAR REVIEW: Six Moon Designs Flight 40-FKT Backpack

By Will Rietveld


When I started this review in 2014 the Flight 40 was offered with two harness options -- traditional shoulder straps or a vest harness. I opted for the vest harness. Since then, to simplify things, SMD has split the original Flight 40 into two separate models. The Flight 40 Backpacker and the Flight 40 FKT. The difference between the two models is that the Flight 40 FKT (tested here) utilizes the Vest Yoke, While the Flight 40 Backpacker uses a more traditional standard Shoulder Yoke. The two packs now have a bungie attachment system on the front instead of the daisy chain on my test pack.

The main updates in the 2015 Flight 40-FKT are as follows:
  •  Adjustable and removable harness. You can choose either the Vest or Standard Shoulder Straps.
  •  Seven different harness options available (4 vest harneses and 3 standard harneses), along with 8 different hip belts. This gives the Flight 40  63 different possible configurations.
  •  SMD now uses  a single bag, vs the dual sizes of before. The volume of the pack is now 44L (vs. 48L before) for the M/L version. The volume listed does not include any of the pocket storage.
  •  Side pockets are now much deeper and have a closure at the top.
  •  A removable hydration is now included.
  •  Features like hip belt pockets, etc. are included in the standard price.
  •  Several new color options are available.

Following is my review of the pre-2015 model:

Six Moon Designs has reinvented and consolidated their backpack line down to two models – the Fusion and the Flight – each in two size capacities.

The Fusion 50 and 65, with a sturdy frame, adjustable torso, and capable suspension are sub 2.5-pound backpacks designed to satisfy the needs of most lightweight backpackers.

The lighter weight Flight 30 and 40 backpacks have a Delrin peripheral loop frame that is anchored to a weight-dispersing hipbelt, and features a unique vest harness. These packs offer extra comfort for backpackers at the lower end of lightweight or the higher end of ultralight.
The vest harness is what triggered my interest in the Flight. Earlier this year I tested the Ultimate Directions Fastpack 20, which also has a vest harness, and was impressed with its carry comfort and freedom of movement from not having a hipbelt. It felt like I was wearing the pack. But a hipbelt-free pack is only comfortable up to a certain point, about 10 pounds.

Nevertheless a vest harness is a refreshingly innovative feature for a backpack, and intrigued me enough to test a backpack with that feature. As you will see the Flight has numerous complementary features that add up to a very comfortable and capable backpack.

 Specifications and Features

Note: the specifications below are for the pack I tested. The weight and some of the pack details have changed on the 2015 version. Go to the Six Moons Designs website to see the current specifications.

Six Moon Designs (www.sixmoondesigns.com)
Flight 40
Sizes Available
S/M, M/L; size M/L tested
S/M is 44 liters total, M/L is 48 liters total
Specified Weight
S/M is 30 oz; M/L is 32 oz
Measured Weight
31.85 oz for size M/L
Pack body is 210 denier Robic, body contact areas are DriGlide, high wear areas are 410 denier PU coated nylon ripstop pack cloth, pockets are high-tenacity 4-way stretch nylon
Delrin rod peripheral frame, vest harness with 6 pockets and two point attachment, 2 sternum straps, load lifters, stiffened removable hipbelt with 2 zippered pockets and 4-pull tightening, hipbelt stabilizers, 2 front stretch mesh pockets, front daisy chain and ice axe loop, side zig-zag compression straps, extension collar, drybag top closure with top compression strap, interior zippered security pocket.
Now $220

The new Six Moon Designs Fusion 40 backpack actually has 48 liters (2900 cubic inches) of volume (which includes the extension collar and pockets) in size M/L, and weighs 32 ounces (2 pounds). The smaller volume Flight 30 (not shown) has 36 liters (2200 cubic inches) of volume in size M/L and weighs 21 ounces.



The following photo series shows the Flight’s notable features and details.

The Backpanel View shows the business side of the Flight. The center is well padded against the backbone. The shoulder straps flare out at the bottom to create the vest harness with two sternum straps. It has a two-point attachment to the pack body. The vest harness has six pockets, two of them zippered. The pack has a total of 10 exterior pockets.

Close up of the vest harness, with red bandanas inserted in the three pockets on each wing. It connects with two sternum straps.

Inside the pack, a peripheral Delrin rod is anchored to a high density polyethylene (HDPE) reinforcement attached to the back of the hipbelt. There is one zippered mesh security pocket on the inside. The pack does not have a sleeve for a hydration reservoir, but there are two loops for hanging one.

The wide padded hipbelt has a thin sheet of HDPE under the outer skin to provide stiffness and distribute weight. It’s tightened with a four-pull system connected to one central buckle. The HDPE layer in the hipbelt has a 6-inch cutout at each end, which allows the hipbelt to wrap and tighten around the hipbone. The hipbelt pockets have a large capacity, a big plus.

The pack’s frontpanel has two large stretch nylon pockets that wrap around the sides, and a combination daisy chain, lower ice axe loop, and upper top compression strap down the middle.

Each side of the pack has a four-point compression system that tightens with one pull. Note that a Platypus hydration system fits nicely in a side pocket.

The top has a 10.5-inch extension collar with a drybag-type closure and top compression strap.

The bottom of the pack, and other abrasion areas, are 410 denier pack cloth. The pack body is 210 denier Robic fabric. Note that the main shoulder strap attachment is to a wing on the bottom of the pack; the other attachment is to a wing located at the top of the side pockets.


Preliminary Testing

I tested the Flight 40 for this First Look article by carrying it on day hikes with 20, 25, and 30 pounds of weight. I loaded the pack with an old sleeping bag to fill it out, and placed 2-liter bottles of water high against the backpanel to simulate a backpacking load. Each hike was about 5 miles and took 2 hours.

My initial impressions of the Flight 40 are as follows:
  • Note that the actual volume of size M/L is 48 liters, not 40 liters.
  • In spite of its lightweight peripheral rod frame (see photo 4), the Flight is a capable load hauler. It easily and comfortably carried everything I put in it, up to 30 pounds. It gave me the impression that it is capable of carrying even more weight, if I am. For a 48 liter pack, the most a hiker is likely to carry is 25 to 30 pounds.
  • Its load carrying ability comes from the peripheral rod frame that is solidly anchored to the back of the hipbelt in the lumbar area, in combination with a stiffened hipbelt that spreads the weight, plus a bifurcated hipbelt that wraps around the hipbones. The pack effectively transferred all the weight to my hips and the hipbelt stayed on my hips, which is remarkable for a 2-pound backpack.
  • I really like the vest harness, it makes the pack feel like it’s being worn rather than carried.
  • I also like the six stow pockets on the vest harness. They are made of stretch nylon and are handy for a digital camera, snacks, or anything used often on the trail. Two of the pockets are zipped.
  • Further, I also really like the large hipbelt pockets, which are the largest attached pockets I know of.
  • Some hikers will miss a hydration sleeve; the Flight doesn’t have one. That doesn’t bother me since I use a 1-liter Platypus flask based hydration system in a side pocket, which is lightweight and convenient. The side pockets on the Flight are perfect for that arrangement.
  • One thing I miss on the Flight is a large stretch mesh pocket on the front of the pack. That’s where I put a large turkey roaster bag containing all of the items I want to keep handy on the trail. Fortunately, that bag of stuff fits into the other side pocket. Overall, however, there seems to be less pocket volume on the front of the Flight, compared to a conventional design with one large front pocket plus two side pockets.
  • The middle strip on the front of the pack measures 4.5 inches wide and has a daisy chain plus 8 attachment loops, enabling the Flight to easily carry items lashed to the front of the pack. For extra capacity, one could attach a tall, narrow gear bag to the front.
  • It is not easy to reach and replace a water bottle carried in a side pocket. The pockets are deep, large, and contain a compression strap within. One is likely to have other items stuffed in the pocket, plus the compression strap interferes, so inserting a bottle back in the pocket (with the pack on) is the challenge.
  • The Flight is built of bomber fabrics. They are very durable and will last a long time, but from a lightweight point of view, they are overkill. The counter argument is that heavier fabric doesn’t contribute much extra weight to a backpack, perhaps 3 to 4 ounces in this case; most of a pack’s weight comes from the frame, reinforced hipbelt, straps, and connectors. 


Field Testing

I carried the Flight 40 on several multi-day backpacks loaded with 21-23 pounds of lightweight gear.

  Although the Flight 40 would seem to be too small in volume for lightweight backpacking, its actual volume (in size M/L) is 48 liters, and it in fact has plenty of volume for a multi-day trip using a true lightweight gear kit. That assumes good gear choices and no unnecessary extras.

This pack's load carrying capacity is indeed remarkable, considering the pack's minimal lightweight frame and overall light weight. It carried the stated loads comfortably all day. That capability is due to a combination of a lightweight Delrin rod loop frame that is anchored to a supportive hipbelt with a four strap tightening system and cutout that molds the hipbelt to your hip bones. This pack is capable of transferring most (if not all) of the pack weight onto your hips.

I tested the pack with the vest harness option (now the FKT model). The vest harness with two sternum straps helps to distribute weight so overall it feels like you are wearing the pack rather than carrying it. The vest also adds lots of pockets to keep things handy. And the hipbelt pockets are the largest I have seen and also hold a lot of stuff.

This is a pack you will want to use with a hydration system because a water bottle in a side pocket is not easily reachable with the pack on, and part of the side compression system is inside the pocket so it is hard to insert a water bottle with the pack on. There is no hydration sleeve inside the pack, so a hydration reservoir would either need to go inside at the top of the load (there are two hose ports) or in a side pocket. My preference is the latter, for easier access and easy monitoring of how much water I have left.

The side stretch mesh pockets are large and hold a lot, but if you use one for carrying water, only limited outside pocket space if left for gear. I personally missed having a large stretch pocket on the front of the pack, along with two side pockets. I like to put all of my smaller items in a large turkey roaster bag (or other dry bag) and stuff that in a large stretch pocket on the front of the pack, but the Flight 40 didn't give me that option. I was able to stuff a smaller version in a side pocket (with a hydration reservoir in the other), but it was less then ideal. The daisy chain in the middle (now a bungie attachment system) allows one to strap a gear bag (or other gear item) onto the front of the pack, which would work okay.


Overall the Flight 40 is a very capable load hauler for its light weight, and I consider its volume to be ample for a multi-day backpack with lightweight gear. Many backpackers fear getting a pack that turns out to be too small in volume, but frankly you are better off to know the volume of your gear kit and match the size of your pack to the size of your load. A right-sized pack that is completely filled carries much better than a oversized pack partially filled. It you must purchase a larger pack "just to be sure its big enough", get one with a good compression system so you can adjust pack volume to get a tight pack no matter the load size. For that approach the Flight 40 is a good choice; it has an excellent side and top compression system.
My main issue with the Flight 40 is the outside pocket design. Granted, a pack designer needs to choose a single design that will please a majority of buyers, and then buyers need to decide if it meets their needs and preferences. I personally prefer a three pocket design that covers the sides and front of the pack with pockets. Other people like a "cleaner look". You need to make your own decision.

Other than the pocket design, I like everything about the Flight 40. Its an amazingly capable and comfortable backpack on target for a true lightweight backpacker.


  1. Just wondering if you had any thoughts towards the torso length of the M/L size. I had read the S/M was quite long in the torso.

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