JoosVos

By an inverted version I mean that the direction of jump-run is opposite to the sum of all wind vector displacements.

I believe that spotting according to the total displacement is the best way to spot.

However you raised the obvious question that the total displacement vector may be opposite to the upper winds ... making the jump-run longer ... Hence I added the inverted version of the spot ... the purpose of this is to decrease the total length of jump-run in an attempt to make the total spot more compact.

You will find that the spot ofter isn't directly into the upper wind ... nor the wind on the ground ... instead the spot will always be in line with the sum of all displacement vectors.

If you would like the calculator to give jump-run directly into the upper wind ... or ground wind ... jump-run offsets will have to be calculated. It is my understanding that not many pilots can accurately fly a jump-run with an offset. (The only benefit would be that jump-run could then be flown directly into the upper wind ... and therefore would most likely be shorter)

However ... before we should worry about this I would like to make sure that the quality of the data the model currently uses is good. I estimate the accuracy of the current model to be approx 20% ... You would only save an additional 10% or so from flying accurate offset jump-runs.

So when the model is perfected to be accurate to less than 10% ... I guess it would be really cool to improve it further ... and include offset jump-run recommendations.

I know this calculator isn't perfect ... but it has proven to be a great tool to help determine the first spot of the day. From then on ... the jump-masters can adjust it depending on how the spot came out.

Again, feedback is greatly appreciated.

Stay safe & have fun!

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I plugged in some numbers for direction and speed and it returned info that was waaaaay off what it should have been.

Plug in some simple numbers that you know should generate a specific result and see.

I'm trying to figure out what it is that putting me out on a downwind and sometimes crosswind jump run.

I may be wrong here....I'm just using simple numbers.

12000 - Direction 270, Speed 15
9000 - Direction 90, Speed 15
6000 - Direction 270, Speed 15
3000 - Direction 90, Speed 15
ground - Direction 270, Speed 15

Results:
The ideal spot is 0.023 miles at heading 92 degrees

The Green (go) light should be switched on -0.877 miles at heading 92 degrees

12000 - Direction Speed 15
9000 - Direction Speed 15
6000 - Direction Speed 15
3000 - Direction Speed 15
ground - Direction Speed 15

The "center" of the spot is 0.023 miles at heading 92 degrees

Caution: Because of the difference in direction in upper winds and total displacement an inverted version is deplayed.

Inverted version: The Green (go) light should be switched on -0.9 miles at heading 270 degrees

Regular version: The Green (go) light should be switched on -0.9 miles at heading 90 degrees

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I made some changes to the spot calculator ... now when the angle of the displacement and the upper winds differ more than 90 degrees ... the sport will be inverted ... shortening the jumprun ... this makes the most sense

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The new and improved

http://www.skydivemidwest.com/spot_calculator/

More feedback is greatly appriciated - I want this thing to work well

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I plugged in some numbers for direction and speed and it returned info that was waaaaay off what it should have been.

Plug in some simple numbers that you know should generate a specific result and see.

I'm trying to figure out what it is that putting me out on a downwind and sometimes crosswind jump run.

I may be wrong here....I'm just using simple numbers.

12000 - Direction 270, Speed 15
9000 - Direction 90, Speed 15
6000 - Direction 270, Speed 15
3000 - Direction 90, Speed 15
ground - Direction 270, Speed 15

Results:
The ideal spot is 0.023 miles at heading 92 degrees

The Green (go) light should be switched on -0.877 miles at heading 92 degrees

Alright ... I figured I'd give some insight into the spot calculator ... the way it works ... the psychological part of spotting etc.

First of all ... the winds you entered don't make much sense as far as a realistic scenario ... and hence it is not very interesting do discuss it in detail ... but since you use this result as evidence that the calculator is flawed I will take some time to explain the results and why they are unsymmetrical.

This is the principle the calculator is based upon.

Adding up 'air-layer' displacements vectors described below:
*(13500-10500) using 12000ft data and 15sec affecting displacement
*(10500-7500) using 9000ft data and 15sec affecting displacement
*(7500-4500) using 6000ft data and 15sec affecting displacement
*(4500-1500) using 3000ft data and 110sec affecting displacement (110sec because part of this descent will be under canopy)
*(1500-00) using ground wind data an 90sec affecting displacement (90sec is a good average for the time period spend under parachute under 1500ft)

This data will determine the jumprun dead center. Meaning the middle jumper on the load should get out at this displacement.

We are not done yet....

Next we have to take into account some other factors:
* The delay from green light to actual exit ... and its associated displacement. This depends on what aircraft you use ... faster aircraft have a greater displacement because they travel further in a shorter amount of time.
For a king-air this is approximately 0.15 miles.
* The airplane forward speed drift after exiting the aircraft. The kinetic energy your body has opposed to air layer you transition to will make you travel an additional 0.15 miles after exit - in the case of a king-air.
* The length of a complete jump-run. This is different for many aircraft ... and load sizes ... but a full load in the king-air is between 1 mile and 1.4 miles long. Smaller loads are obviously shorter.

So lets say we have no wind ... meaning no additional displacement aside from the three major factors listed above ... a spot would look something like this

Greenlightdistance = 0 - greentodoordelay - freefalldrift - (lenghtofjumprun / 2)

A spot with no wind in the King Air therefore should be about 0.9 Miles prior ... and understand that the first jumper under parachute will in fact be under paracute 0.6 miles prior to the center of the airfield and the last jumper will be under canopy 0.6 miles after.

So aside from obvious variations on jump-run length - and other factors that are not taken into account ... this model fairly accurate.

Over the last summer we at Skydive Midwest have done our best to adjust variables to make the spot calculator more accurate - and have enjoyed very, very few off landings since.

Also ... keep in mind that the human mind tends to be drawn to spotting short on windy days ... and long on no-wind days.

Also ... offset jump-runs maybe something an experienced pilot can perform accurately ... but with a proper heading the gains are minimal. Therefore the calculator doesn't include an offset. If anybody would be interested in having an offset included let me know, I like a challenge. ;-)

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In conclusion - people that want to can use this tool to help determine the first spot of the day - hopefully eliminating the dummy loads and the clash of egos over who knows best. Also I would love to make this tool better and more accurate so I invite suggestions and feedback.

Mainly we are looking for the following aircraft data:

jump-run speed
your delay from light till actual exit (use a stopwatch etc ... lets be scientific here :-))
the average length of jump-run (in miles - this has to be very accurate )

Alright everybody, have a great week!
...Its late ... I'm gonna hit the hay.

I pull at 5200 - newer sets - meaning releasing drogue

at 5800 - older sets

if the spot is really short with high winds ... i'll take it to 4600 ... in efford not to land off airport

if the spot is long ... really long ... I'll pull at 6000

Pull wherever you're comfortable - it's all good as long as you don't pull lower than 4500 - and always do a handle check early on in freefall

Bram Clement

A very good teacher - by the book - fair - very proffessional - reliable and available

My drill;

Seatbelt until 1500ft
Hook up lowers at 1500ft and take seatbelt(s) off
(this way the student can't 'fall' out)
Hook up uppers aprox 2000ft below exit alt.

In case of emergency exit - quick hook up one/both upper(s). (Comfort is a factor...

jumped for a while time without helmet.

Risers have caused me -
bloody fingers (don't try to control the opening)
bloody neck and ears (no helmet)
hits causing headaches

It is worth it to wear a helmet - openings can really hurt!

A friend of mine couldn't jump for two days from getting his head (with protec) stuck between the risers.

... it's still skydiving

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...Why restrict students above 500ft - why is that good?

My thinking is that it may keep them from driving all over the sky while in their landing pattern. Everybody going the same direction does its part in preventing collisions. One of my worst fears is seeing a first-jump student spinning a 360 on downwind without clearing airspace...and the potential results.

Ok ... I see ... why don't you say no more than 180? That way they have 360 range. If they turned on final too high or too short. They can turn around ... and turn back without drifting crosswind too much.

Do you use radio?

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How the hell are you supposed to turn on to final if no 90's lower than 500ft? USPA recomends you enter the down wind at 1000ft, and for the retards out there that means that you need to make 2 more 90's.

tome it down a bit man

I believe that a 360 can be usefull over 1000ft for losing altitude

Below 1000ft I don't believe you should restrict canopy traffic - 90 max turn will limit the student to a 180 total range - I really don't see the use for this

A 360 turn eats up around 200ft with student size canopies ... give or take

Why restrict students above 500ft - why is that good?

I've watched the video several times - I really can't see any major faults on the JM's side ... besides losing the student :-) ... looks like the student is flying a strong de-arched body position and pushes both legs down underneath her

Maybe if this went out the door stable they could've kept it stable ... but it didn't ... and they didn't keep it stable

I don't think the guys did such a bad job - not every AFF jump will go smoothly - that is why you teach a student what to do when both I's are gone ... because that CAN happen

...

and on this jump it did

...

Ok, I guess we agree.

The thing is that I can think of some situations when pulling the reserve first could cause problems.

Let say - you pull - trapdoor effect (drogue collapses) - and you keep speeding up - nothing happens - you pull your reserve first

BUT - it was a baglock

If you make the mistake of pulling you reserve before cutting away - you will likely end up with a main/reserve entanglement

I think it is dangerous to generate specific responses to odd malfunctions when the regular procedure would also do.

I understand your fear of terminal reserve openings - but it doesn't have to take long to pull your cutaway handle - is it worth it to skip that step and possibly end up with a entanglement (in case you mistake the baglock for a bridle failure)

Right - it is all about muscle memory - that is what people fall back upon when the unexpected happens.

About the entanglement.. I get it.. keep fighting

Thanks for the reply

I agree - it, arguably, could be better NOT to cutaway before pulling the reserve in this situation.

430lbs is a rather light tandem - it would come down to about 185lbs instructor and 185lbs student and 60lbs of gear.

there is a reason for current recommended procedures - there are lots of different things that can happen on a tandem jump - you have to keep it simple.

Long story short - going for the reserve right away wouldn't be bad in this situation specifically - but neither would cutting away first

In the light of all that can happen on a tandem jump/deployment - I believe that it is best to keep it simple.

drogue - main - secondary - cutaway - reserve - rsl

straight for reserve when: hardpull on drogue or bridle/drogue entanglement only.

It is simply arrogant to assume you will be aware of the exact nature of your malfuncion when it happens.

Thanks for your reply - I understand your perspective.

ps: How are you going to deal with an entanglement on a tandem? - I wouldn't know

I bought a different altimeter (low profile) because student kept grabbing mine - going for the handle....

A hand camera is out of the question!

Now on later level skydives - with unstable manuevers I have taken my helmet cam with

That is very valuable for a debrief...

..... and ......

Maintain your gear - don't wait untill it breaks

When you are the jumper - you don't have the time to figure out what is going on - replay the video - etc

Keep it simple

drogue - primary ripcord - secondary ripcord - cutaway - reserve - rsl (in that order)

Only staight for the reserve when
- hardpull on the drogue (ie student graps right hand)
- drogue or bridle entanglement that won't clear

just a thought

The sigma openes shitty sometimes - and ofter turns sluggisch - but does very well in turbulence and is pretty forgiving

The Hop has much more forward speed - flatter glide - low toggle pressure and on no/low wind days a powerfull flare BUT when you hit that bump just before landing... it can hurt

At our DZ we have Sigma's Hop's and a A-2... on windy days we jump Sigma on no/low wind the hop and a-2

That A-2 flies really nice btw!

I thought I lost it there - finally people are making sense. Thanks for the post!

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Sorry if this is a thread hijack, but I've been looking at the numbers on my Neptune.

Our exit altitude is 11000ft. It's the highest in the country, and is equalled by 2 other DZ's. Our DZ is 5000ft AMSL and going higher creates hypoxia issues requiring O2, etc.
An AFF L1 begins deployment sequence at 5500ft.
Main side needs to secure the pull by 4000ft.
If they fail, reserve side needs to secure the pull by 3500ft.

Then the AFF I's need separation. We need to be under canopy by 2000ft.

For the life of me, with over 2000 AFF dives, I cannot see a scenario where being open with your student after clearing your airspace and ensuring horizontal separation from the other AFF I and the camera person is even remotely possible.

Our AFF students are on radio, and the duty instructor - who remains on the ground - deals with radio for all AFF students still on double instructor levels, and all SL students prior to PRCP's. If they cannot fly a pattern, they do not pass to single Instructor levels/PRCP's.

The thought that not being open with your student is somehow doing them a dis-service irks me somewhat. I have been doing AFF since 1992, and have not yet had a student "lose" me. If this process of being open with the student is so required, why are our SL students not followed out by a senior jumper, or why are there not 3 AFF instructors, 2 for freefall and 1 for canopy coaching.

I think the efforts to "open with the student" pose far, far more risk to the AFF team than properly training the student to land without assistance prior to embarking on AFF L1. Our radio is not used if the student is responding as trained. We have paddles as a back up should the radio fail.

t

thanks for the post

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...How does it help to pull high with a student and fly with them for landing - what are you going to say "hey student" "follow me!" ?! :-)

Exactly! NOW you're getting it!
Wouldn't it be nice for the confused student to have someone nearby that could guide them in...either to the LZ or to a good alternative landing area? And to assist in case of an off-landing injury???

So you are saying you should be that close you can talk to the student - .... you ride through the opening ... track and pull ... how are you supposed to get back up to the students flying level - for one .... what do you tell them ahead... follow the yellow parachute ... what if they follow somebody else ... do they follow all the way in for landing ... what about staying clear of other traffic ... I guess I see so many obsticales for this ... tell me how does this work?!

Also, why not have a radio with BOTH AFFIs simply for the off-landing scenario if nothing else?

Good Idea!

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For the life of me, with over 2000 AFF dives, I cannot see a scenario where being open with your student after clearing your airspace and ensuring horizontal separation from the other AFF I and the camera person is even remotely possible.

The thought that not being open with your student is somehow doing them a dis-service irks me somewhat.

I think the efforts to "open with the student" pose far, far more risk to the AFF team than properly training the student to land without assistance prior to embarking on AFF L1. Our radio is not used if the student is responding as trained. We have paddles as a back up should the radio fail.

I believe that what is being suggested is for one of the JMs to be open to guide the student in the event of a high altitude opening.
I am not terribly experienced as an instructor only having around 500 actual instructional jumps and I have only had one scenario where the student was opened above 10k, I had to pull them out as it was my only option before loosing the student – it was a really wild ride!
I was the only JM on the dive and buzzed it down to the ground ASAP to get on the radio. The student landed where she was supposed to with MINIMAL radio assistance because the ground training was through and complete. So opening high was not at all necessary and my first priority was to follow the plan, to land and be on radio.
Radios sometimes fail as well, I have that happen a few times but no issues have been created by that so far.

I fail to understand how a “disservice” has been created.

thank you for your post

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Sorry to see that:

1) you apparently assume that all goes well on every student jump.
2) you seem to think that all DZs have a "base station" operating.
3) you apparently have little concern for students' general welfare.
4) you missed the reference to "confused" students.


You post relates nothing that would contradict any of those line items.

see above

You know an awful lot about me I guess. How does it help to pull high with a student and fly with them for landing - what are you going to say "hey student" "follow me!" ?! :-)

maybe pull high - fly up to them - and drag 'm to the landing area by the pilot chute.... sounds good

or

pull high - float - put both feet in the center A's or students canopy and help him find the dropzone flying around a two-stack?

OR

'I' lands - talks to student via radio - meanwhile base-station is already talking to student while 'I' is on the way down - if all else fails student can SEE where the other parachutes are going and landing

No - doesn't matter - was just wondering

I don't think you should 'stay up with a student' - I believe you can be more of a help on the ground - when you use a radio - if the case is that the student needs to see canopies to find his/her way back to the dz they can still do so - even if the I lands a lot sooner

I haven't seen anybody jump different gear on AFF jumps yet - not saying nobody does.

Thanks for the post.

took a football player up last summer 315lbs... wasn't so bad actually - as long as you don't jump a 182 or similar. Went out of the PAC

I always work myself up when I get a 240 + student... but it never seems to be much of a problem.

I would never let somebody help me flare - a friend of mine hurt his leg bad doing that. A small girl helped him flare but lock her elbows... you don't know what they are going to do...