what are blood grooves for?

For looks and to reduce over al weight of the knife. The blood part of the name is just a myth.
 
As stated, the name "blood groove" is based on a myth. Anyone who believes it has obviously never used a knife to puncture an animal's body cavity. It makes no difference.
They are usually used to reduce weight while preserving strength (same physics principles behind the "I-beam"). In the case of the Pilot's Survival Knife made by Camillus and Ontario, the groove also has the added benefit of allowing the blade to turn during use, when the sawback is used for its intended role (sawing through aluminum aircraft skins). If there were no fuller in the blade, it would be much more difficult to rotate the blade to make curved cuts, while it's plunged into a rigid piece of metal.

Done and done.
 
As far as I can tell, the "blood groove" is basically for looks. It makes a knife look better, or worse. Like with the Pilot's knife above, they can have a purpose, but usually it's just aesthetics.

Edit: Forgot to add that the suction thing is a myth. If you were to stab some type of flesh, it would just conform to the groove itself, unless it had some sort of screen covering over the groove. 3 cheers for physics!
 
I don't think I buy the making it easier to make curved cuts in metal statement. As mentioned the metal is rigid, so there being a dip in the middle of the blade isn't going to matter because the blade comes back out to full thickness where it will make contact with the metal at both edges of the blade. Also, is it really made to cut through aluminum aircraft skin? How many times would a pilots knife actually be used for that purpose?
 
FlaMtnBkr said:
Also, is it really made to cut through aluminum aircraft skin? How many times would a pilots knife actually be used for that purpose?
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Yes it was designed for cutting the aluminum skin of an aircraft. I have no idea how many people have actually had to use them for this though.
 
Aren't cockpit glass, doors, and emergency exits how most pilots would exit the aircraft in an emergency? Cutting a hole through the skin to escape seems like it would take too long while plummeting towards the earth. Maybe I'm missing the point of cutting through the skin?
 
Although there are failsafes, even ejection seats and canopy bubbles have been known to fail to work as designed. If you happened to have a crash landing - especially in an area far from help - and survive, the aircraft's frame may very well be crushed, and the exists rendered inoperable.

In these cases, the amount of aluminum you would need to cut through would be much less than on an intact plane.

The intent of having a survival knife is just that--as long as you survive the landing, you are going to need tools to exit from the plane, and also to survive for a time until help arrives.

A good pilot, up to date on his or her training, and assuming clear terrain for landing, can actually land a plane that has lost the majority of its engines fairly safely. My dad, a pilot, has had to make emergency landings on several occasions. Once, while in the Navy, the propeller came off of one of the turboprops, and tore through the fuselage; he made an emergency landing on a beach, without injuries or further serious damage to the plane. There's a really neat looking plaque with a ~2x4 foot section of the aircraft skin where the propeller exited the other end of the plane in his study.
 
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I guess you can never predict what will happen in a disaster and any tool is better than nothing. I guess the design is from WW2? I know my dad didn't get such a knife as a pilot in the Navy during the Vietnam era. Did many planes have ejection seats during WW2? Sorry for the tangent.
 
Cold Kill said:
As far as I can tell, the "blood groove" is basically for looks. It makes a knife look better, or worse. Like with the Pilot's knife above, they can have a purpose, but usually it's just aesthetics.

Edit: Forgot to add that the suction thing is a myth. If you were to stab some type of flesh, it would just conform to the groove itself, unless it had some sort of screen covering over the groove. 3 cheers for physics!
Click to expand...

Um, you need to read the post right above yours. It says everything you need to know about why "fullers" exist on knife and sword blades.
 
Keep in mind, the Camillus/Ontario pilot's knife was designed quite a long time ago, when aircraft were made differently than they are today.
I haven't used mine to saw out of any aircraft, but I have tested the principle on the thin metal skin of an old refrigerator door. In terms of geometry and physics, it makes sense once you see it in action. Don't think I'd want to have to cut my way out of an 1/8"-thick aluminum shell with one, though.
 
Also in addition to reducing overall weight they can be used to manipulate distribution of mass along the length of a blade, which can change its handling and performance characteristics. :)
 
I read some ware in a story about the history of the ka-bar that the fuller was added for strength, and it helps to prevent the blade from flexing.
similer to the way the folded center section in a sheet of card board works.
 
I believe the first fuller used in a knife was as designed by Webster Marble in his ideal fixed blade, the first real hunting knife. It made the blade lighter although still stronger than most knives of the day. Kabar copied Marbles design, only with a smaller fuller that didn't really change the weight of the knife. The blood groove myth probably came about from soldiers carrying Kabars wondering what the non-functional groove along the blade was for.
 
I was always under the impression that fullers are only really useful on swords, because along the length of a 25"+ blade, you could save quite a few ounces of steel! but on any average size knife, I don't see how it will noticibly lighten the blade. Did not know the bit about the aircraft survival, I had always assumed they were there because people thought they looked cool and made money
 
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