24
$\begingroup$

Military parachutes for use by humans (both paratroopers and distressed aircrew) tend to be of simple round or (more recently) cruciform design:

round military parachutes

(Image by the United States Army, via Wikimedia Commons.)

cruciform military parachutes

(Image by the United States Army, via Flickr, via Wikimedia Commons.)

These are simple drag parachutes, generating no lift. In contrast, sport parachutists nowadays almost invariably use much-more-advanced rectangular or elliptical ram-air parachutes, which generate much lift and relatively little drag:

sporting ram-air parachute

(Image by John [shebalso] at Flickr, via Wikimedia Commons.)

Military use of ram-air parachutes is essentially limited to display teams.

This seems rather odd, given that lifting ram-air parachutes:

  • allow for much lower descent rates (and, thus, softer touchdowns - something which would be especially important for paratroopers, who jump with lots more heavy gear than sport skydivers, and ejectees, who are likely already injured, and, thus, tend to have less ability to tolerate hard touchdowns) than drag parachutes, due to their greater aerodynamic efficiency;
  • allow their users to glide considerable horizontal distances once deployed and can be manoeuvred nimbly, which would:
    • allow paratroops to be dropped some distance from a target and glide silently in;
    • allow wind-induced dispersal of a large paratroop unit to be negated;
    • allow paratroops to manoeuvre to land in a suitable area or to evade antiaircraft fire;
    • allow ejectees to glide towards territory controlled by friendly forces and/or terrain with the least potential for further exacerbating any injuries to the ejectee.

So why do military users stick with drag parachutes rather than moving to lifting ram-air parachutes?

$\endgroup$
14
  • 3
    $\begingroup$ I don't know for sure but I assume it's because it's easier to get your weapon out of you aren't busy flying the chute, plus remember that these are 18 year old kids with nearly 100lbs of equipment, armor, and supplies. The chutes also make decent cover/shelter. $\endgroup$
    – Ron Beyer
    Jul 9 at 0:48
  • 35
    $\begingroup$ How long do you want to linger in the air when hostiles are shooting at you? $\endgroup$
    – MaxW
    Jul 9 at 8:31
  • 13
    $\begingroup$ "allow paratroops to manoeuvre to land in a suitable area or to evade antiaircraft fire;" Show me proof that you can evade bullets simply by changing the shape of your parachute, then I agree with you. $\endgroup$
    – EarlGrey
    Jul 9 at 9:28
  • 9
    $\begingroup$ "allow paratroops to be dropped some distance from a target and glide silently in" I'm sure some military branches do have experience with this. Usually those are the branches that take less photographs of their manoeuvrers. $\endgroup$
    – Mast
    Jul 9 at 13:56
  • 16
    $\begingroup$ I'd just like to add something that I don't think warrants a full answer. I couldn't find public domain pictures easily, but image search 'paratrooper deployment'. The point of these is to land large numbers of troops. The air can be pretty densely packed with troopers and their parachutes. Do you want 1,000 18 year old kids deployed in close proximity to all be steering their own highly maneuverable parachutes? $\endgroup$ Jul 9 at 19:53
52
$\begingroup$

You’ve made some faulty assumptions there as the military does use square chutes for specialist parachuting, but rounds are popular for several reason:

  • Static-line round chutes are deployable en-masse from a much lower altitude / height than square chutes. The lowest that we can drop the round chute is 400’ (which is very low) versus circa 1500’ for a square.

  • They require the least amount of training to get the user competent to jump out of the two. Since the chute isn’t steerable, the soldier is reliant on the aircraft crew to make sure they are despatched in the correct position in space to arrive at the DZ. So their only job is to run forward when the light goes green and follow the guy in front out of the door then action their drills and brace. Remember this is only their method of egressing the aircraft to get to the ground and fight and it’s not a particularly covert method of entry. This provides a large degree of force concentration, the largest number of people out of the aircraft and onto the ground in one go.

  • Square chutes are steerable and can be deployed in several ways and at much higher altitudes/ heights to allow the user to either free fall from height down to a low altitude before actuating they chute, or to use static line or pull immediately after jumping to fly in to the DZ from as far away as possible. This is a much more covert method of entry and requires a lot more training to achieve with inherently greater risks. Hence it’s not for everyone and isn’t usually given the media attention that round chutes get. This boils down to some assumptions that people have that the government / military operations have almost infinite resource to train and keep people competent in high-end skills whereas almost the opposite is true and keeping it simple is usually the preferred option.

$\endgroup$
16
  • 8
    $\begingroup$ Also for emergency egress, the user may be unconscious from the ~18G ejection, so they wouldn't be able to steer anyway. And have exactly zero training. $\endgroup$
    – Jan Hudec
    Jul 9 at 5:31
  • 25
    $\begingroup$ Also, when you're hanging in mid-air, you make a rather nice target. So you generally want to get on the ground fast, not hang around enjoying the view like a sport parachutist. $\endgroup$
    – jamesqf
    Jul 9 at 5:41
  • 27
    $\begingroup$ One factor may be that if the paratroopers deploy on "dumb" chutes, very rapidly, then they will tend to fall in the same staggered pattern all the way in. If they all started wheeling around the place on steerable parachutes they would not just need to train in how to operate the chute but also in "flying" safely in a big pack. $\endgroup$ Jul 9 at 9:04
  • 13
    $\begingroup$ @JanHudec I had an uncle (now dead) who survived when his Lancaster was shot down by a German night-fighter. His position was one that was usually unsurvivable. He recovered consciousness with his chute open and no knowledge of leaving the aircraft or opening his parachute. $\endgroup$ Jul 9 at 12:25
  • 13
    $\begingroup$ Its worth noting that some units like the SAS and US Marine Corps Recon do use ram air parachutes for case of inserting small numbers of high skill forces covertly. So its different parachutes for different roles. $\endgroup$ Jul 9 at 15:04
3
$\begingroup$

As Arkem stated, they use both, but the primary reason for the use of a simplified parachute is just that it's simplified. In general Airborne troopers are supposed to fall where they are told to, as intended by the pilot, as instructed by the wing commander, as ordered by the REMFs.
When you give that same trooper the ability to adjust their flight path then you add in all manner of variables that are not only unnecessary, but dangerously unpredictable.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.