Russian Paratroopers to Land on Drifting Arctic Ice [Archive]

A_Van

18th Feb 2016, 14:19

Rock Hudson is, of course, number 1 in this nomination. On the intelligence side, I would add Alec Baldwin as a CIA analyst (Jack Ryan) in "The Hunt for Red October" :-)

As for the article, the current Russian defence minister loves shows since his times with the emergency management ministry. Poor polar bears....

BEagle

18th Feb 2016, 15:24

I recall the tragic occasion some years ago when several jumpers made fatal dents in the Antarctic.

I've always suspected that failure to apply temperature correction to their altimeters caused them to deploy their canopies lower than they intended, with a higher vertical velocity than planned.

I trust that our Russian chums won't make a similar error.

skydiver69

18th Feb 2016, 16:16

I've always suspected that failure to apply temperature correction to their altimeters caused them to deploy their canopies lower than they intended, with a higher vertical velocity than planned.

IIRC it was to do with the failure to notice or to take into account the difference between ground level at the take off point compared to the DZ.

KenV

18th Feb 2016, 16:41

I've always suspected that failure to apply temperature correction to their altimeters caused them to deploy their canopies lower than they intended, with a higher vertical velocity than planned.
I'm confused here. For freefall/HALO jumpers, they are at terminal velocity long long before they get anywhere near the ground, so I don't understand the bit about "higher vertical velocity than planned."

And for static line jumpers, they don't deploy their canopies at all. It's done for them when they reach the end of the static line. So if the canopies deployed too low, it was because the airplanes they jumped from were too low.

Can someone clear up my confusion?

KenV

18th Feb 2016, 16:45

IIRC it was to do with the failure to notice or to take into account the difference between ground level at the take off point compared to the DZ. Since the Russians are jumping onto drifting ice, their DZ is at seal level. So the only way this could be of concern for them is if they take off from an airport well below sea level. Seems unlikely.

str12

18th Feb 2016, 17:12

Perhaps they didn't want to land at terminal velocity but wanted something more conducive to life?

Pontius Navigator

18th Feb 2016, 17:34

If they land at seal level are they at risk of being eaten by the said seals?

Trim Stab

18th Feb 2016, 18:09

I'm confused here. For freefall/HALO jumpers, they are at terminal velocity long long before they get anywhere near the ground, so I don't understand the bit about "higher vertical velocity than planned."

The South Pole is about 9500ft above MSL, so air is thinner, so the velocity when they would have intended to pull their rip-cords would have been higher than for a jump at sea level.

skydiver69

18th Feb 2016, 18:11

Since the Russians are jumping onto drifting ice, their DZ is at seal level. So the only way this could be of concern for them is if they take off from an airport well below sea level. Seems unlikely.

Ken I was responding to Beagle recollection of a different and much earlier event.

KenV

18th Feb 2016, 19:08

Ken V. Perhaps they didn't want to land at terminal velocity but wanted something more conducive to life? I think that's a reasonable assumption. The question I had is how does delaying their opening cause them to descend faster than terminal velocity? That seems impossible. Or did I misunderstand the statement?

Tourist

18th Feb 2016, 20:17

Since terminal velocity reduces with altitude, and cold air is denser, I can't imagine why....

Fonsini

19th Feb 2016, 00:53

Ice Statio Zebra also revealed several military secrets, not least of which was the ability of the MiG 21 to fly from a Russian base to a point 320 miles WNW of Nord, Greenland - do 2 low passes, and return safely to base on internal fuel only. Quite a feat in 45 minutes, bet the Lightning couldn't do that :E

NutLoose

19th Feb 2016, 01:23

They better get Clint Eastwood and the Firefox out of there before they arrive.

Trim Stab

19th Feb 2016, 05:52

Since terminal velocity reduces with altitude, and cold air is denser, I can't imagine why....

More correctly, terminal velocity reduces with density altitude. At South Pole, approx 9500ft amsl, and with summer temps around -20, density altitude would have been about 5000ft. Still high enough to increase terminal velocity by around 8%.

BEagle

19th Feb 2016, 07:30

Oh my, do RTFP, KenV!

I wrote 'vertical', not 'terminal' velocity.

:rolleyes:

Pontius Navigator

19th Feb 2016, 08:35

BEagle, he also made the assumption that they had jumped with a sufficiently great altitude to reach TV before planned chute opening. And indeed the TV at altitude will be higher than the TV at chute opening height.

But at a lower height TV may not be achieved before chute opening but as you say, the VV may well be higher than planned.

FODPlod

19th Feb 2016, 08:46

It seems to be open season on KenV every day in this forum, doesn't it?

What interests me more are the arrangements to exfil the paratroopers after they land. Any information?

Union Jack

19th Feb 2016, 10:33

KenV

19th Feb 2016, 14:03

Oh my, do RTFP, KenV! I wrote 'vertical', not 'terminal' velocity.

Dearest Beagle. Please read what I wrote and not what others assumed I wrote.

I said that for a freefall/HALO jump, vertical velocity at canopy opening IS terminal velocity. I politely stated I was confused and politely asked for clarification.

I also said that for a static line jump, canopy opening, and thus vertical velocity, is determined by the length of the static line which is independent of any altimeter the jumper may be wearing. I politely stated I was confused and politely asked for clarification.

Thank for your F'ing reply, but it did nothing to clear up my confusion. So I politely ask once again, please clarify my confusion.

KenV

19th Feb 2016, 14:07

Since terminal velocity reduces with altitude, and cold air is denser, I can't imagine why.... Which rather points up my confusion. If they delayed their opening, then they would be lower when they opened, which would reduce rather than increase their terminal velocity. So I state politely again, I'm confused and politely request clarification.

pasta

19th Feb 2016, 14:14

KenV - on this side of the pond we have a habit of understating things slightly more than you might be used to.

By "lower than intended" I should imagine BEagle meant "lower than ground level".

When descending by parachute, it's desirable to arrive at ground level with a sufficiently low vertical velocity to be able to absorb the impact with one's legs. In this case, the parachutists in question arrived at ground level "with a higher vertical velocity than planned."

Does that help?

BEagle

19th Feb 2016, 14:14

1. The plan was to freefall.

2. Then to open the canopy at a certain altitude.

3. At the planned altitude the parachutists would have been at a certain velocity, but not at terminal velocity.

4. If altimeter temperature error correction hadn't been applied in such cold weather, the actual altitude would be lower than planned.

5. Hence the vertical velocity would have been higher than planned.

6. The parachutes would have taken longer to reduce the vertical velocity to the normal parachute descent rate.

7. A combination of lower level and higher vertical speed when the parachutes were deployed might therefore have proved fatal.

Did anyone else not understand that line of thought from my original post?

As an example, if it was ISA-45 and they'd planned to pull at 500 ft, their actual altitude would have been only 380 ft and depending on the height at which they'd exited, they could have fallen 120 ft further than planned, perhaps accelerating beyond the capability of the parachute to develop fully?

KenV

19th Feb 2016, 14:34

BEAGLE:
At the planned (opening) altitude the parachutists would have been at a certain velocity, but not at terminal velocity.Then I am more confused. It takes about 15 seconds for a human body to reach terminal velocity. Less if they are encumbered with heavy equipment like weapons. I've never encountered a military freefall jump where the freefall was planned for less than 15 seconds. In my experience, such a short freefall would be pointless and a static line jump would be preferable. And if it was planned for less than 15 seconds, they'd use a stop watch, not an altimeter to determine their opening point. Brits (or whoever did this jump) must have very different tactics or procedures than the American tactics/procedures I'm familiar with. That explains things. Thanks for the clarification.

Did anyone else not understand that line of thought from my original post? Pasta clearly did not. He offered an entirely different explanation.

pasta

19th Feb 2016, 14:44

If it's the incident I'm thinking of, one parachutist deployed too low; two failed to deploy at all.

BEagle

19th Feb 2016, 15:06

Neither were they military parachutists.....:rolleyes:

O-P

19th Feb 2016, 15:10

Ken,

How does the persons weight (with heavy equipment), alter the time it takes to reach terminal velocity? Perhaps there is a new form of gravity I'm not aware of.

KenV

19th Feb 2016, 15:14

Neither were they military parachutists.....:rolleyes:These were sport jumpers?!! And they planned a jump with a freefall that never reached terminal velocity? And that was done at such low altitude that opening just a very few seconds late would result in their death? Not even smoke jumpers do that, and they arguably take the greatest risks of any jumpers. Before I was confused and your previous reply cleared that up. My confusion was caused by a difference of procedure. But now I'm incredulous. I've never encountered sport jumpers that planned such jumps. Never. I must live a very sheltered life.

KenV

19th Feb 2016, 15:36

Ken,How does the persons weight (with heavy equipment), alter the time it takes to reach terminal velocity? Perhaps there is a new form of gravity I'm not aware of. Dearest O-P,

Cross sectional density is the primary driver of an object's terminal velocity. Putting heavy equipment on a human body makes the human body more dense which "alters the time it takes to reach terminal velocity". Reducing the cross section (like going straight head down vs spread eagled) also "alters the time it takes to reach terminal velocity." If gravity alone were at work as you suggest (like perhaps on the moon) you would be correct that neither mass nor density would have such an effect. But then there would be no terminal velocity at all and the max velocity from a free fall would be the escape velocity.

O-P

19th Feb 2016, 15:48

Ken,

I beg to differ. Two objects with identical Cd and frontal area, but with differing mass, will fall at exactly the same rate.

KenV

19th Feb 2016, 16:24

I beg to differ. Two objects with identical Cd and frontal area, but with differing mass, will fall at exactly the same rate.So a human being of mass 100 kg and that same human being of mass 300 kg will have the same terminal velocity? Ummm, no.

Terminal velocity is reached when the drag force equals the mass force. It is a very simple balancing equation.

If the Cd and frontal area are identical, their drag is identical and the resulting drag force will be identical for any given speed. Since one object is heavier, the mass force of one object will be greater than the other. Since they have identical drag force, the heavier object must have higher terminal velocity. It is very simple and basic math.

FODPlod

19th Feb 2016, 17:41

What interests me more are the arrangements to exfil the paratroopers after they land. Any information? - FODPlod

In the immortal words of the port lookout:

"On the beam a submarine
On the bow, another cow"

Jack

Nearly 100 paratroopers (http://barentsobserver.com/en/security/2015/04/russian-paratroopers-landed-near-north-pole-08-04)? A submarine? That's surprising. An ice breaker was used in other instances:

Russian Arctic scientists to be evacuated (http://barentsobserver.com/en/arctic/2015/08/russian-arctic-scientists-be-evacuated-ice-floe-05-08)

I'd be very interested in reading the source of your information, please?

Union Jack

19th Feb 2016, 18:47

I'd be very interested in reading the source of your information, please?

My apologies, FODPlod - I was of course having a bit of fun in the spirit of "Ice Station Zebra", and hence the:D

Jack

taxydual

19th Feb 2016, 19:41

Cor. What a lot I've learned.

Terminal velocity
Cd
Mass
Drag Force
Cross Sectional Density

Everyday is a school day.

The biggest thing I've learned though

Russian Paratroopers to Land on Drifting Arctic Ice

All of them are F'ing barmy.

NutLoose

19th Feb 2016, 19:59

I hope the RAF paras are ok

RAF parachute instructors collided mid air during training jump - Mirror Online (http://www.mirror.co.uk/news/uk-news/raf-parachute-instructors-collided-mid-7340013)

KenV

19th Feb 2016, 20:00

FWIW, the Russians used an interesting parachute system like nothing we (USA) use. It's a combination static line system and free fall deploy system. The static line deploys/extracts a small drogue chute, the troops drop to a preset altitude at a reduced velocity free fall because of the drogue, and then the main chute is extracted by the drogue by some kind of automated system. Don't know if the auto system is timer based or altitude based or both. And it has a steerable ram air airfoil type canopy. Fascinating.

LINK (http://tvzvezda.ru/news/forces/content/201504080912-e7qr.htm)

And it's hard to be certain but in the video it looked like one jumper's drogue collapsed/burst during his drop. They have a manual reserve, but the video did not show that.

Tourist

19th Feb 2016, 20:39

Ken,

I beg to differ. Two objects with identical Cd and frontal area, but with differing mass, will fall at exactly the same rate.

Methinks you misunderstood your teacher during that lesson....:rolleyes:

O-P

19th Feb 2016, 21:56

Tourist,

Do explain how mass affects gravity in a freefall acceleration.

Basil

20th Feb 2016, 08:51

Do explain how mass affects gravity in a freefall acceleration.
Ah, but it isn't acceleration they're discussing; it's TV and I'd tend to agree with KenV that WEIGHT*=THRUST
DRAG= Cd 1/2 p V^2 S
Assuming that the parachutist falls in the face-down attitude then Cd will be largely constant.
Therefore since thrust is increased, say doubled with a military load, then TV will be higher but, due to the V variable being squared, nothing like doubled.

*ie mass in a gravitational field.

Re the 'dent in the ice' wrong subscale setting seems to me the most likely explanation.

BEagle

20th Feb 2016, 08:53

O-P, what you assert is correct in a vacuum - but not otherwise.

Take a piece of A4 paper and drop it out of the window. Now take an A4 piece of steel and repeat the experiment - I think that you'll find that the time taken to reach the ground is rather less for the latter case.

?v=5C5_dOEyAfk

Two forces are acting on the object, weight (mg) and drag (Cd½ρV²S); the resultant force which accelerates the body is (weight-drag) and only weight has a mass term. As the body accelerates, drag increases until it is equal to weight, at which point there is no further acceleration and the body is descending at terminal velocity.

O-P

21st Feb 2016, 00:04

Basil/Beagle,

Thanks for your polite responses. Rather than pure mass, it's a mix of surface area and Cd that affect the drag rate.

Ken, I apologize. Tourist go **** your self.

Ken, I guess a 300kg human will hit the same TV as 100kg human if the drag characteristics are right...like weapons.

Sorry Ken, I was wrong.

BEagle

21st Feb 2016, 07:31

I've edited my post to correct the formula for Drag - it should have been Drag = Cd½ρV²S.

Tourist

21st Feb 2016, 10:10

Ken, I apologize. Tourist go **** your self.

Methinks you misunderstood your parents when they tried to teach you manners too.....

Backinblack

23rd Feb 2016, 10:48

What interests me more are the arrangements to exfil the paratroopers after they land. Any information? - FODPlod

This is their first jump:
https://www.youtube.com/watch?v=w32kaOYb7lo

Dougie M

23rd Feb 2016, 14:14

The VDV seem to prefer their reefed drogue dispatch system which may be due to the drop speed of an IL76. I can't see it throttling back to 115kts. The drop itself from the helmet cam was about 50secs, half of it in "attenuated free fall" (about the same speed as in a tandem fun jump) That would equate to about 4000ft. The phase under the main canopy was about the same which equates to about 500ft so the release height would have been around 5000ft mark or 1500m. The troops weren't on oxygen so the mid level scenario fits.
UK Freefall qualifying height is 12000ft. Oxygen is used by the jumpers at or above this height. The terminal velocity of a para in the standard posture shown is around 120kts.

http://i1299.photobucket.com/albums/ag76/dougiemarsh/5f548a76-c7a5-4af9-b7de-e8f9f80d7511_zpsm3l5dfzy.png

Top Bunk Tester

24th Feb 2016, 10:26

beardy

24th Feb 2016, 10:53

Icetrek - BARNEO ICE CAMP (http://www.icetrek.com/barneo-ice-camp.html)

There was a very interesting documentary about this.

http://www.channel5.com/show/north-pole-ice-airport

The 'civilian' parachutists prepare the runway.

Barneo is a seasonal camp, set-up in late March every year only through a highly complex and technical series of logistics incorporating Ilyushin-76, Antonov-74 and Mi-8 flights from Moscow and Siberia, parachute and skydiver drops, specialist advisers and observers and temporary camps on the Arctic Ocean. Once the ice runway has been prepared, using tractors parachuted onto the ice, technical AN-74 flights deliver the camp infrastructure and Barneo usually opens its doors to the first passenger flight around April 2.

KenV

24th Feb 2016, 17:38

For a comprehensive analysis of the Antartic accident see the following link:
Tragedy in Antarctica | Parachutist Online (http://parachutistonline.com/feature/tragedy-in-antarctica%E2%80%94-lessons-from-the-south-pole)So the account on post #26 was wrong on several counts:

The jump most certainly was planned to freefall to terminal velocity.
The plan was to deploy at 5000 ft AGL after a 4000 ft freefall. (Typical planning)
A 5000 ft AGL pull altitude would have given lots of margin for multiple errors. (Good planning.)
The tragedy was not a result of altimeter error due to cold.
The cause was hypoxia of the jumpers. (Very very bad planning and a major violation of the Skydiver's Information Manual.)
The three dead jumpers never used oxygen during the climb.
The three that died did not pull "too late." They never pulled at all.
None of the dead jumpers had auto deploy devices (moderately bad planning, but not a violation.)
The three surviving jumpers all used oxygen at least part time during the climb by sharing a single portable O2 bottle with the pilot. (bad planning and a violation, but just good enough to survive, if just barely.)
The lone surviving single jumper had an auto deploy device and it fired. (good planning.)
The other two survivors jumped tandem, did not suffer hypoxia and manually pulled as planned at 5000 ft AGL. (good planning)

Still a tragic event, but very different than what was originally described.
Also very very different than what the Russians did. No comparison at all between the antarctic tragedy and the Russian arctic jump.

KenV

24th Feb 2016, 17:42

Therefore since thrust is increased, say doubled with a military load, then TV will be higher but, due to the V variable being squared, nothing like doubled.Assuming all else is equal, terminal velocity varies as the square root of the increase in mass. So mass must be four times greater to double the terminal velocity.

KenV

24th Feb 2016, 17:57

The VDV seem to prefer their reefed drogue dispatch system which may be due to the drop speed of an IL76. The US Military jumped for decades out of the C-141 which is very similar to the IL-76 and have never (to my knowledge) used such a system. And they continue to jump out of the C-17 which has a similar jump airspeed. The C-17 is a STOL design and can fly slower than the C-141, but that requires full flaps/slats and high AOA which results in a high deck angle. The C-17 deck angle may not exceed 4 degrees during a jump which requires an airspeed similar to C-141. I doubt that IL-76 jump airspeed is significantly higher, if at all. And interestingly, they jump single stick off the Ilyushin's ramp, not double stick out of side doors. Very different in multiple ways.

KenV

24th Feb 2016, 18:08

What interests me more are the arrangements to exfil the paratroopers after they land. Any information? They apparently jumped onto an ice flow that has an ice runway that civilian aircraft can use. Apparently, when their arctic training is done they board a jet and fly home. No Ice Station Zebra submarines.

LINK (http://www.icetrek.com/barneo-ice-camp.html)

Skymong

6th Mar 2016, 05:09

The US Military jumped for decades out of the C-141 which is very similar to the IL-76 and have never (to my knowledge) used such a system. And they continue to jump out of the C-17 which has a similar jump airspeed. The C-17 is a STOL design and can fly slower than the C-141, but that requires full flaps/slats and high AOA which results in a high deck angle. The C-17 deck angle may not exceed 4 degrees during a jump which requires an airspeed similar to C-141. I doubt that IL-76 jump airspeed is significantly higher, if at all. And interestingly, they jump single stick off the Ilyushin's ramp, not double stick out of side doors. Very different in multiple ways.

They are jumping squares not rounds hence the single-stick. The parachute is deployed by either a timer or pressure device allowing it to be used across a wide range of altitudes.
I'm guessing the use of the drogue means that body position is less important on those jumps that have any significant freefall time, thus circumventing the need for the training associated with MFF ops.