Change Forum... Civil Aviation Travel, Polls & Prefs Tech/Ops Aviation Hobby Aviation Photography Photography Feedback Trip Reports Military Av & Space Non-Aviation Site Related LIVE Chat My Starred Topics | Profile | New Topic | Forum Index | Help | Search
 Military Halo Jump (Tech Question)
 wardialer From United States of America, joined Sep 2001, 1194 posts, RR: 0Posted Mon Jul 11 2011 23:14:20 UTC (4 years 3 weeks 1 day 23 hours ago) and read 30568 times:

 For example, how long would a free fall take from 30000 feet to ground level? Is there a simple formula for this? I know ground level is not realistic since you are closure to the gorund, of course, you need to deploy the parachute. But this is just for an example. Or, lets say from 30000 feet to "Opening Altitude" which would be like around 7000 feet. How long would the free fall take from 30000 feet to 7000 feet? thx.
 tugger From United States of America, joined Apr 2006, 6145 posts, RR: 10 Reply 1, posted Mon Jul 11 2011 23:58:31 UTC (4 years 3 weeks 1 day 22 hours ago) and read 30564 times:

 Quoting wardialer (Thread starter):For example, how long would a free fall take from 30000 feet to ground level? Is there a simple formula for this? I know ground level is not realistic since you are closure to the gorund, of course, you need to deploy the parachute. But this is just for an example. Or, lets say from 30000 feet to "Opening Altitude" which would be like around 7000 feet. How long would the free fall take from 30000 feet to 7000 feet?

Though it is of course mission specific, I am betting they would more likely open at less than 2,800 AGL. That's a "normal" low safe open altitude for fun jumpers. Basically 2,800' gives you time to pull and if there is a problem with your main chute, to cut away and open your reserve and reorient yourself for a landing.

For a military HALO operation though they quite likely would open lower than that to minimize any chance of being seen by others. They wouldn't be as concerned about the risk of a chute not opening as each is packed professionally and the worry isn't about a problem with a chute opening (which happens rarely anyway). If you open at 7,000' you would give people on the ground about 7 minutes to spot you. Technically they could open as low as 1,000' but that is really low and doesn't leave much time to orient yourself for landing.

So with that said, and using this freefall calculator: http://keisan.casio.com/has10/SpecExec.cgi, the freefall time would be around 75 seconds (30k to 2k)

Tugg

 I don’t know that I am unafraid to be myself, but it is hard to be somebody else. -W. Shatner
 mffoda From United States of America, joined Apr 2010, 1169 posts, RR: 0 Reply 2, posted Tue Jul 12 2011 09:54:59 UTC (4 years 3 weeks 1 day 12 hours ago) and read 30456 times:

 In MFF Operations (HALO), the typical opening altitude for a training jump is 4000' AGL. (will depend on experience level to some extent)... As far as FF time/speed is concerned, It is approx. 120 mph or 55 mps. That works out to be approx. 5.6 seconds per 1000'. (however, one must reach terminal velocity first.)
 harder than woodpecker lips...
 tugger From United States of America, joined Apr 2006, 6145 posts, RR: 10 Reply 3, posted Tue Jul 12 2011 10:10:39 UTC (4 years 3 weeks 1 day 12 hours ago) and read 30445 times:

 Quoting mffoda (Reply 2):In MFF Operations (HALO), the typical opening altitude for a training jump is 4000' AGL. (will depend on experience level to some extent)... As far as FF time/speed is concerned, It is approx. 120 mph or 55 mps. That works out to be approx. 5.6 seconds per 1000'. (however, one must reach terminal velocity first.)

That calculation only works with lower altitudes "thick" air (normal max "fun jump" altitude is 14,000' so no oxygen is needed for the ride), the thinner the air the higher the terminal velocity, hence the shorter the freefall times.
For example in 1960, when Captain Joseph Kittinger jumped from 102,800', he fell for 4 minutes and 36 seconds and reached a maximum speed of 614 mph. That's 276 seconds to fall 89,000' (he popped his chute at 14k').

Tugg

 I don’t know that I am unafraid to be myself, but it is hard to be somebody else. -W. Shatner
 wardialer From United States of America, joined Sep 2001, 1194 posts, RR: 0 Reply 4, posted Tue Jul 12 2011 10:24:53 UTC (4 years 3 weeks 1 day 12 hours ago) and read 30438 times:

 Tugger - The calculator link does not work. Can you please post another alternate link? Thx. Or, can this formula be done from a regular standard calculator? I was going also ask you what speed did you enter to give the 75 second fall result from 30K to 2K? Also, what is more covert? HALO or HAHO? And I cannot understand why HAHO would be covert as well because the chutes open at a much HIGHER altitude compared to HALO and enemies may spot you if one glides down at a very very slow rate of descent.[Edited 2011-07-12 10:26:27]
 tugger From United States of America, joined Apr 2006, 6145 posts, RR: 10 Reply 5, posted Tue Jul 12 2011 11:09:06 UTC (4 years 3 weeks 1 day 11 hours ago) and read 30415 times:

 Quoting wardialer (Reply 4):Tugger - The calculator link does not work. Can you please post another alternate link? Thx. Or, can this formula be done from a regular standard calculator? I was going also ask you what speed did you enter to give the 75 second fall result from 30K to 2K?

Hmmm, lets try this:
Free fall (time and velocity)

If the link works you'll see that the calculation is fairly easy and if your calculator can handle equations then it can do it. Basically its a straightforward curve. The key difficulty is factoring in the thinner atmosphere which reduces drag and increases freefall speed at the higher altitudes. Ergo the freefall speed decreases as you go lower in the atmosphere and the air gets thicker and drag increases.

I didn't enter in any speed as it is the gravitational constant of 9.8m/s2, the only variable is "how high".

 Quoting wardialer (Reply 4):Also, what is more covert? HALO or HAHO? And I cannot understand why HAHO would be covert as well because the chutes open at a much HIGHER altitude compared to HALO and enemies may spot you if one glides down at a very very slow rate of descent.

They are two different types of operations. If you have airspace access then HALO is fine but if you do not have the ability to get near the airspace of the intended target without being detected then HAHO can be used. A HAHO team can be deployed many, many miles outside an opponents airspace and fly under canopy to the intended target. Basically a HAHO relies on the fact that a person under a canopy is a very small radar target, and for all intents and purposes is undetectable to radar. HAHO usually uses the cover of night to minimize visual detection.

So they are covert because the opponent cannot see them coming.

And you can actually combine HAHO and HALO ops, you go HAHO to enter airspace then "remove" your canopy and do a HALO to drop down quickly and get to the ground.

Tugg

[Edited 2011-07-12 11:16:53]

 I don’t know that I am unafraid to be myself, but it is hard to be somebody else. -W. Shatner
 mffoda From United States of America, joined Apr 2010, 1169 posts, RR: 0 Reply 6, posted Tue Jul 12 2011 13:13:37 UTC (4 years 3 weeks 1 day 9 hours ago) and read 30355 times:

 Quoting tugger (Reply 3):Quoting mffoda (Reply 2): In MFF Operations (HALO), the typical opening altitude for a training jump is 4000' AGL. (will depend on experience level to some extent)... As far as FF time/speed is concerned, It is approx. 120 mph or 55 mps. That works out to be approx. 5.6 seconds per 1000'. (however, one must reach terminal velocity first.) That calculation only works with lower altitudes "thick" air (normal max "fun jump" altitude is 14,000' so no oxygen is needed for the ride), the thinner the air the higher the terminal velocity, hence the shorter the freefall times. For example in 1960, when Captain Joseph Kittinger jumped from 102,800', he fell for 4 minutes and 36 seconds and reached a maximum speed of 614 mph. That's 276 seconds to fall 89,000' (he popped his chute at 14k'). Tugg

I am well aware that air is thinner as one increases altitude... But, there is a tremendous difference between 25-30k' f vs. 102k'.

the link below is from the United States parachute association.

http://www.uspa.org/Portals/0/SIM/Freefall_Table.pdf

The table lists the various Exit Altitudes (feet) with an opening altitude of 3,000'.

Example: Exit altitude 14,000', freefall distance 11,000', FF speed 120 mph, FF time 66 seconds. (with given terminal velocity)

Interestingly... 11,000' (11) x (5.6) (from my earlier post) = 61.6 seconds + (however, one must reach terminal velocity first.) = 66 seconds.

 harder than woodpecker lips...
 mffoda From United States of America, joined Apr 2010, 1169 posts, RR: 0 Reply 7, posted Tue Jul 12 2011 13:38:20 UTC (4 years 3 weeks 1 day 8 hours ago) and read 30347 times:

 Quoting wardialer (Reply 4): what is more covert? HALO or HAHO?

HAHO is more clandestine, because the A/C is further from infiltration point and generally out of sight and sound. With today's generation of parachutes a haho operation from 30k' could provide a offset of between 60-80 kilometers. (depending on wind and equipment load.)

 Quoting tugger (Reply 5):And you can actually combine HAHO and HALO ops, you go HAHO to enter airspace then "remove" your canopy and do a HALO to drop down quickly and get to the ground.

"enter airspace then "remove" your canopy"

You are going to have to explain that one to me?? Are you suggesting cutting your main chute away?

 harder than woodpecker lips...
 tugger From United States of America, joined Apr 2006, 6145 posts, RR: 10 Reply 8, posted Tue Jul 12 2011 13:59:37 UTC (4 years 3 weeks 1 day 8 hours ago) and read 30336 times:

 Quoting mffoda (Reply 6):I am well aware that air is thinner as one increases altitude... But, there is a tremendous difference between 25-30k' f vs. 102k'.

I understand, and I was certainly not implying anything about your knowledge in my response. Merely pointing out that the 5.6 calc doesn't work for a 30k' drop.

My big glaring mistake is that the calculator I posted and used is most definitely wrong and I did not check the number properly (I trusted the calculator, my bad    ). It did not factor in drag which means its assuming freefall in a vacuum, which is of course very wrong. I'll chalk up my failure to it being late when I first posted and then rushing this morning and not properly vetting my numbers.    Ah well....

This calculator from the same site does take drag into account:
Free fall with air resistance (time and velocity)

And it calculates a time of approximately 144 seconds for a 200lb person falling 28,000 feet. time will of course change for varying weights (a 300lb person takes just 120 seconds) and wind resistance (i.e. drag or "size" of the person falling).

Again my apologies for providing incorrect times.

Tugg

 I don’t know that I am unafraid to be myself, but it is hard to be somebody else. -W. Shatner
 tugger From United States of America, joined Apr 2006, 6145 posts, RR: 10 Reply 9, posted Tue Jul 12 2011 14:18:31 UTC (4 years 3 weeks 1 day 8 hours ago) and read 30318 times:

 Quoting mffoda (Reply 7):"enter airspace then "remove" your canopy" You are going to have to explain that one to me?? Are you suggesting cutting your main chute away? Wow!

Yes, that can be done!

Not hard to have multiple chutes, every skydiver already jumps with two, a main and a reserve. For a military operation, it all depends on the requirements of the mission. It is easy enough to pop your second canopy when you reach the desired altitude.

Normal civilian skydivers have done this before (though it is not something that is normally done), intentionally jumping with multiple mains, popping the first at a high altitude, then cutting the first one away and freefalling again and then popping their "main main" (still keeping the reserve available).

The first canopy can take a long time to drift to the ground and land a looong way from the LZ. For a military ops you wouldn't just let the canopy go as it can lead to you discovery. Instead it is "removed" from use and concealed (how that would be done so there is no risk to the skydiver I have no idea) or destroyed after it is cut away (incendiary device?).

Tugg

 I don’t know that I am unafraid to be myself, but it is hard to be somebody else. -W. Shatner
 mffoda From United States of America, joined Apr 2010, 1169 posts, RR: 0 Reply 10, posted Tue Jul 12 2011 15:04:23 UTC (4 years 3 weeks 1 day 7 hours ago) and read 30297 times:

 Quoting tugger (Reply 9):Yes, that can be done!

The only military unit that routinely did or does cut away's is the USAPT (Golden Knights). They would attach a 3rd canopy (round) to the front of their harness and use it to demonstrate a malfunctioning canopy.

No military unit that I have ever worked with has ever utilized a 3rd canopy in the manner in witch you suggest.

On the other hand, we have done a variation of HAHO... HAMO, where we would freefall to a medium altitude of approx. 12,500' before deploying the main canopy.

btw tugger... do you know what the first 3 letters of my screen name stand for?

 harder than woodpecker lips...
 tugger From United States of America, joined Apr 2006, 6145 posts, RR: 10 Reply 11, posted Tue Jul 12 2011 15:54:30 UTC (4 years 3 weeks 1 day 6 hours ago) and read 30268 times:

 Quoting mffoda (Reply 10):The only military unit that routinely did or does cut away's is the USAPT (Golden Knights). They would attach a 3rd canopy (round) to the front of their harness and use it to demonstrate a malfunctioning canopy. No military unit that I have ever worked with has ever utilized a 3rd canopy in the manner in witch you suggest. On the other hand, we have done a variation of HAHO... HAMO, where we would freefall to a medium altitude of approx. 12,500' before deploying the main canopy.

On the multiple canopy options, I don't doubt you (I would be foolish to do so), all I was saying is it can be done. There would be very few situations where it would be. And if you say you haven't seen it then I can't argue.

 Quoting mffoda (Reply 10):btw tugger... do you know what the first 3 letters of my screen name stand for?

Well after a quick google I did! And I will assume that you are not using ODA improperly. So hats off to you, sir.

After your first post I suspected (hey, this is A.net, I've learned) that you knew what you were talking about and noticed "MFF" matched your name. Quite possibly you have fallen a few thousand miles.

And though I don't have much air under me, happily I am not a Wuffo.

Tugg

[Edited 2011-07-12 15:55:24]

 I don’t know that I am unafraid to be myself, but it is hard to be somebody else. -W. Shatner
 mffoda From United States of America, joined Apr 2010, 1169 posts, RR: 0 Reply 12, posted Tue Jul 12 2011 17:33:37 UTC (4 years 3 weeks 1 day 5 hours ago) and read 30240 times:

 Quoting tugger (Reply 11):happily I am not a Wuffo.

No harm done tugg...

 harder than woodpecker lips...
 wardialer From United States of America, joined Sep 2001, 1194 posts, RR: 0 Reply 13, posted Tue Jul 12 2011 22:14:37 UTC (4 years 3 weeks 1 day ago) and read 30153 times:

 I usually done it this way given the AVERAGE speeds for example: From 30000feet to 2000 feet would equal 28000 feet difference which turns out to be 5.30 miles. (28000 / 5280). Then take the 5.30 miles / 150mph (150 is just an average example I use) and that then turns out to be 2.11 minutes. 1 mile = 5280 feet So just take the jumping starting alt of 30000 feet and the opening chute alt of 2000 feet = 28000 difference = 5.3 miles. Then take the 5.3 miles divide that by 150 and you get 0.0353 and then X that by 60 = 2.11 minutes on a standard calculator. Of course, it will not be accurate because it depends on weight, density alt, and so forth. Its just a rough estimate on the freefall before opening begins....[Edited 2011-07-12 22:26:53]
 tugger From United States of America, joined Apr 2006, 6145 posts, RR: 10 Reply 14, posted Wed Jul 13 2011 11:33:29 UTC (4 years 3 weeks 11 hours ago) and read 29993 times:

 Quoting mffoda (Reply 12):No harm done tugg...

So I have a question. Normally I always set my altimeter on the ground at the LZ. A simple way to know when you wanted to open, i.e. when you were close enough to the ground. With MFF you don't have that. How do you set a firm opening altitude? Atmospheric pressure reports for the area? Laser/ground altimeter? Something else? Just curious. Thanks.

Tugg

 I don’t know that I am unafraid to be myself, but it is hard to be somebody else. -W. Shatner
 mffoda From United States of America, joined Apr 2010, 1169 posts, RR: 0 Reply 15, posted Thu Jul 14 2011 11:02:34 UTC (4 years 2 weeks 6 days 11 hours ago) and read 29858 times:

The easiest way is to set the altimeter at the departure airfield, by adding or subtracting the difference from the DZ / IP (map data). You can also get elevation, barometric pressure and wind direction from the A/C and sometimes nearby airfields.

Rgds,

 harder than woodpecker lips...
 wardialer From United States of America, joined Sep 2001, 1194 posts, RR: 0 Reply 16, posted Fri Jul 15 2011 10:19:13 UTC (4 years 2 weeks 5 days 12 hours ago) and read 29720 times:

 http://www.paragear.com/catalog/PICTURES/altimeters/I1170-3.jpg In the pic above, what type of altitude does this measure? The sea alt or the AGL alt for skydiving operations? I always see these on HALO jump operations on ones wrist I suppose it is MSL rather than AGL....I dont know for sure....Please, can someone verfiy? BTW - I got an offer to try out skydiving, but not for the military though....Its more of a recreational jump from a Mi-8 helicopter.....Question is, is a military operations junp more reliable than these recreational ones? I have to get myself prepared for this....
 Top Of Page Change Forum... Civil Aviation Travel, Polls & Prefs Tech/Ops Aviation Hobby Aviation Photography Photography Feedback Trip Reports Military Av & Space Non-Aviation Site Related LIVE Chat Forum Index

Reply To This Topic Military Halo Jump (Tech Question)
• Military aviation related posts only!
• Not military related? Use the other forums
• No adverts of any kind. This includes web pages.
• No hostile language or criticizing of others.
• Do not post copyright protected material.
• Use relevant and describing topics.
• DETAILED RULES

 Similar topics: More similar topics...
Overseas Leisure Travel Military Question. posted Thu Sep 20 2007 23:10:00 by Mike89406
Military TAF Question? posted Tue Apr 5 2005 20:49:43 by Jourdan747
Military Meteorology Question posted Mon Nov 8 2004 20:42:08 by Dl757Md
Very Hard Military Plane Question... Give It A Go! posted Tue Mar 23 2004 22:46:50 by MartinairYYZ
Military ATC Question posted Sun Jan 27 2002 02:11:10 by N1641
Question About "Top Gun" posted Mon Jun 6 2011 10:07:54 by Airimages
Military Watches Used By Navy SEALs? posted Sat May 28 2011 12:30:59 by wardialer
UN Military Operations In The Ivory Coast posted Mon Apr 4 2011 16:49:37 by Bthebest
Best Non Fction Military Aviation Book Ever! posted Fri Mar 25 2011 23:27:17 by geezer
Tracking Military Aircraft? posted Sun Mar 20 2011 04:32:53 by eugegall
Overseas Leisure Travel Military Question. posted Thu Sep 20 2007 23:10:00 by Mike89406
Military TAF Question? posted Tue Apr 5 2005 20:49:43 by Jourdan747
Military Meteorology Question posted Mon Nov 8 2004 20:42:08 by Dl757Md
Very Hard Military Plane Question... Give It A Go! posted Tue Mar 23 2004 22:46:50 by MartinairYYZ
Military ATC Question posted Sun Jan 27 2002 02:11:10 by N1641
Best Military Open Houses? posted Sat May 12 2012 18:18:55 by gegtim
Military Technology Systems Podcasts? posted Wed Apr 25 2012 09:57:47 by wardialer
Question About Orbiters At KSC posted Sat Apr 14 2012 12:53:31 by HaveBlue
Delta 737 Landing At Jnas Question posted Sat Apr 7 2012 22:29:49 by HaveBlue
Very Hard Military Plane Question... Give It A Go! posted Tue Mar 23 2004 22:46:50 by MartinairYYZ
Military ATC Question posted Sun Jan 27 2002 02:11:10 by N1641
Fake Chinese Parts On US Military Aircraft posted Tue May 22 2012 11:42:09 by chuchoteur
Best Military Open Houses? posted Sat May 12 2012 18:18:55 by gegtim
Military Technology Systems Podcasts? posted Wed Apr 25 2012 09:57:47 by wardialer
Question About Orbiters At KSC posted Sat Apr 14 2012 12:53:31 by HaveBlue
Question About Swiss Military Activity posted Sat Sep 25 2010 10:36:13 by BlueElephant
Overseas Leisure Travel Military Question. posted Thu Sep 20 2007 23:10:00 by Mike89406
Military TAF Question? posted Tue Apr 5 2005 20:49:43 by Jourdan747
Military Meteorology Question posted Mon Nov 8 2004 20:42:08 by Dl757Md
Very Hard Military Plane Question... Give It A Go! posted Tue Mar 23 2004 22:46:50 by MartinairYYZ
Military ATC Question posted Sun Jan 27 2002 02:11:10 by N1641
Fake Chinese Parts On US Military Aircraft posted Tue May 22 2012 11:42:09 by chuchoteur
Best Military Open Houses? posted Sat May 12 2012 18:18:55 by gegtim
Military Technology Systems Podcasts? posted Wed Apr 25 2012 09:57:47 by wardialer
Question About Orbiters At KSC posted Sat Apr 14 2012 12:53:31 by HaveBlue
Military Meteorology Question posted Mon Nov 8 2004 20:42:08 by Dl757Md
Very Hard Military Plane Question... Give It A Go! posted Tue Mar 23 2004 22:46:50 by MartinairYYZ
Military ATC Question posted Sun Jan 27 2002 02:11:10 by N1641
US Military Troop Charters (Non-specific)? posted Sun Dec 30 2012 18:01:51 by Sevensixtyseven
Military Aviation (Mostly) Humor posted Wed Nov 21 2012 07:16:32 by Geezer
Russian Military Plane Bucket Lav? posted Thu Nov 15 2012 10:43:40 by bonusonus
Photo Essay About Russian Military A/c posted Wed Nov 14 2012 19:27:13 by boacvc10