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chuckakers

Spotting calculator

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I agree ... spotting should be learned the old fashioned way first! Look at the forecast, do the math in your head, make a plan, and finally get in the plane and stick your head out the door. I can do it and every student rolling off the assembly line should be able to do as well.

I'm not trying to replace spotting skills with a calculator. I'm just trying to help DZs & Jumpers get this info faster so they can make better informed decisions as well as to help instructors train students how to spot (can you say visual aide). ;)

Mostly into developing software these days (web sites, databases, & simulations). At the DZ you'll find me with the other 'vidiots' looking for something to shoot ;)

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So, my buddy has been sucked into the wonderful amazement of the waste of time on this sight. First, Digi, your doing a lot more for the sport than the people giving you a hard time on this sight so don't let it discourage you. Second, I would be more than happy to stop by and help with the program over some coffee. 3rd, Stick to your friends for help and assistance because forums are full of people like Mr. 99 years experience that have nothing better to do than screw with you. The few people that will give positive assistance will not out way the computer drama is my life crowd. 4th and most important, no offense to any, if you can't come up with a functional jump run and spot within 30 seconds of a weather report in your head that will put you in position to make it back to the airport easily without concern, go play golf and argue about the type of grass on the green.:S

Beware of Wandering Minions!!!

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I have used DJ's programs for about 8 years now and I recomend them. The spotting calculator that he has been developing and tweaking would do well at most DZs now days,, since most DZ planes use GPS to release the jumpers and the majority of people that jump at bigger aircraft DZs have NO CLUE how to spot. He'll most never even look down when the GREEN light comes on!!!!!
The simplicity of the program and the VISUAL aspect is one he'll of a teaching aid all in itself!!!!
SONIC BEEF #1 BASE 708, NC BASE 3
SLI,IADI,AFFI.TIE.FAA Rigger, Single & Multi Commercial Pilot,CFI, CFII, MEI

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Oh and another of my 2 cents, if you can't do the spotting thing I mentioned above, you instructors failed you terribly. No complicated pull of gravity with the moon, the amount of drag on you goggles, crap added in, but a simple way to calculate a functional spot, you instructors failed you. [:/]

On the other hand, I think your program needs a little tweaking, and we have discussed it a load, and I have failed to assist the way I should have with it, but what you are doing is amazing and appreciated by many, keep up the good work buddy and i will see you soon!

Beware of Wandering Minions!!!

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I've made some updates to the 'Spotting Calculator' for you as requested...

1. If you are not logged in there is a link to request a login now plus appropriate 'Jumpers Notes'.
2. The 'Release' circle is based on 30 seconds at aircraft jumprun speed.
3. The 'Opening' circle is half the Release diameter.
4. I've added Bearing, Distance, & Lat/Lng to the mouse move (bottom of map).

Thanks for all your input & support!
Mostly into developing software these days (web sites, databases, & simulations). At the DZ you'll find me with the other 'vidiots' looking for something to shoot ;)

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Again [popsjumper] you show yourself for what you are! You took the bait again but now sadly; there is no 'Catch & Release' for you. You've shown your colors as you turned to run & hide by deleting our posts. Delete this post too if you want, but you and I both know I've got your number and it's a zero.



:D:D:D
You attribute those deleted posts to ME? Not mine. It's a pretty asshole thing to do to try to say that the deleted posts are mine knowing full well they were not.
OK, dude, here's my colors for you... You, sir, are acting like a real asshole.

So now after all your whining and crying because you didn't get the pat on the head you were fishing for you fix it up a little and add a little info on how to use it so it works better?

Congrats. You're done.
My reality and yours are quite different.
I think we're all Bozos on this bus.
Falcon5232, SCS8170, SCSA353, POPS9398, DS239

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The "drift value" is some constant divided by the vertical speed.



Actually no .. the drift values for freefall & canopy are the amounts of horizontal drift (in meters) experienced per one thousand feet of vertical travel. These values are multiplied by the speed of the wind at that altitude to produce the total drift experienced. This drift distance along with the wind heading determines the direction of horizontal travel.



Let me try again...

D = C/V
where D is your drift value,
V is the vertical speed,
C is some constant.

Solve for C:
C = D*V

You think 3 is a good value for a belly flyer. V is perhaps 50 m/s for them so C becomes 150.

Now lets assume we want to find the D value for someone free flying at 65 m/s. Then D becomes 150/65 which as about 2.3.

Then we want to find the D value for someone that is flying a fast canopy. V is 10m/s, D becomes 15.


See how easy it is when you start out with something that is easy to understand like vertical speed instead of some semi-magic constant?

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I do see what you are getting at but I'm just explaining how I'm doing it. I learned the math from this publication, put together by some long forgotten rocket scientists, so please take a look ... http://www.fas.org/irp/doddir/army/fm3-05-211.pdf Page 247 ... It also contains allot of other interesting Military skydiving information for the non Military jumpers out there.

I took this method and instead of averaging or dog-legging I went the other way. As you can see averaging just makes it easier for us humans to do it by hand. As I'm using a computer, I can easily go the other way by doing more with the same information. So my program automatically gets & subdivides the winds aloft data into 200 foot altitude increments. Calculating the drift for a 16k jump this way gives me 80 drift vectors vs. the 5 you get from winds aloft data or the 1 you get from averaging. Hey, it's a computer, it likes doing long mundane repetitive calculations ;)

The bottom line here is there are still too many variables (e.g. air density, old/unreliable forecasts, jumper movement, changes in vertical speed (exit, tracking, opening), not to mention what we do while in canopy flight) for any computer application to take into consideration and still be user friendly. Anyway, I think my program does a pretty fast & accurate job of getting you into the ball park with the known information available ... but it can't get you to home plate. Getting to home plate still depends on, where the pilot puts you out, what you do while in freefall, and even more on what you do while under canopy.
Mostly into developing software these days (web sites, databases, & simulations). At the DZ you'll find me with the other 'vidiots' looking for something to shoot ;)

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I have an idea and need some genius (or other capable person) to help make it happen. I think it would be a handy thing. Here's the idea.

I lot of areas of the country have winds at very different directions and speeds at different altitudes at certain times of the year. Here in southeast Texas for example, in the winter we can have ground winds from the south at 5, while the uppers at 13k are screaming 70 from the west or northwest. Complicating matters, the wind will actually change direction slowly as the altitude changes, creating a constantly changing drift direction.

I want to have a simple way to calculate where the "perfect" spot is by using something like excel or other common application. I want to input the wind speed and direction at the commonly reported altitudes (as reported by flight service, or observed by the pilot on previous loads using GPS) like 3k, 6k, 9k, 12k, along with the exit and deployment altitudes and the type of jump (think different speeds equals different freefall times equals different amounts of drift) and have it tell me where the spot is - measured in distance from a target like the peas or center of the landing area. Kind of a high-tech way to throw a WDI, but includes freefall in the calculation. The spreadsheet figures out the cumulative drift distance and direction, then reverses that to display the distance and direction needed to exit from any given point.

It would work for any group from headdowners to wingsuiters, and for any target location.

Any takers?



This is what i came up with. If you have EXCEL, feel free to put info in top form. If not, simply use the top one as an example and print it out to use when writing the info in on bottom half.

Before you all go crazy with your "know it all BS" about glide paths, wingloading, canopy brands, etc., calculating the spot for a load of jumpers is just a 'calculated guess' with known margins of error that require the canopy pilot to have the ability to fly out of anyway.

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I couldn't find any accounting for forward throw?

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Before you all go crazy with your "know it all BS" about glide paths, wingloading, canopy brands, etc., calculating the spot for a load of jumpers is just a 'calculated guess' with known margins of error that require the canopy pilot to have the ability to fly out of anyway.



Yep, all those variables would have to be calculated on a case-by-case basis if you wanted to account for all them, I agree.

I like to calculate the prefect spot for round canopies having no forward drive which is what one had to do "back in the day" and what is determined when using a WDI.

Fortunately for us these days, our ram-air canopies with lots of drive can overcome those margins and increase the possibility of landing on target as shown on page 200 of the 2009-2010 SIM. If one lands off, it's because...
1) the jumper opened outside the boundaries of that cone or,
2) the spot was off

Accounting for first and last exit points for the number and types of groups on the load is relatively easy after one determines exit separation requirements.

The one variable that is hard to account for is the winds aloft. What you get from weather services is an estimate at a particular point in time for a particular region of space and can be radically different at the DZ. That's why I call the first load Wind Test Dummies...all in good humor of course.
:D:D

All in all, your spreadsheet is much easier to use than others and is quite straight forward.

As an aside,
- if you ever go to Deland, ask Mike Johnston for the winds aloft board.
- if you ever jump with Mike Mullins piloting, be sure to calculate the spot and tell him where you want to exit.
:D:D;)
My reality and yours are quite different.
I think we're all Bozos on this bus.
Falcon5232, SCS8170, SCSA353, POPS9398, DS239

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What's funny, is I came up with this based on a homework assignment that Mike Wadkins gave me on teaching spotting a few days ago as part of our S/L I course. BTW, I notice your from STF. He had just been at your DZ prior to ours. Anyway, it was just an idea I had to help teach students the principle idea of spotting. Mike liked it.

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I like to calculate the prefect spot for round canopies having no forward drive which is what one had to do "back in the day" and what is determined when using a WDI.



Spotting “back in the day” was part science, part voodoo and a lot gut feeling. You could get ground winds by checking the flag at take off but uppers where sometimes hard to come by. When doing “big ways” with 2 or 3 DC-3’s it got really tough. Because of the formation the lead pilot would not give you a true cut and the added airspeed and prop blast would scatter the exit more. One of the big variables was trying to figure the “jam up time”, how long it was going to take before you heard the “hup” after calling the cut. On the ground it might take 10 or 12 seconds and in the air it would be 15 to 18 or more seconds. Because you were trying to spot for all round reserves that time difference could be a big deal. More than once I can remember hanging outside of a DC-3, with no floater handles, looking down watching the spot go to hell because some clown dicking around in line up.
But now we have the lemming light and all those problems are a thing of the past.

Sparky
My idea of a fair fight is clubbing baby seals

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That is funny, lemming light is quite appropriate for some.

Our GPS has not been picking up the satelites the last few days and we have been manually spotting and determining winds from orbiting, it has been quite cool going back to grass roots.

Buying an new GPS is not so cool.

any suggestions on a good unit?
"When the power of love overcomes the love of power, then the world will see peace." - 'Jimi' Hendrix

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Hi there,

I am keen as to check out that calculator, My version of XL will not open it, what version was used to create that calculator/xl document?
"When the power of love overcomes the love of power, then the world will see peace." - 'Jimi' Hendrix

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I have xl 2003.

even somebody else with a current verion of xl could save it and then save as an earlier viersion could they not?
"When the power of love overcomes the love of power, then the world will see peace." - 'Jimi' Hendrix

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I can open the document fine, but it opens as a "read only" file so I can't experiment with it. Any ideas?



Do a "File | Save As" and save it to your computer. After that you should be able to open and modify it. (In Excel, "read only" just means you can't save any changes to the original file that you linked to.)

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I have xl 2003.

even somebody else with a current verion of xl could save it and then save as an earlier viersion could they not?



You should at least Install the compatibility pack. If nothing else, download it and install it. Here's a link to Service Pack 3 and also the Compatibility pack

Here's office 2003 service pack 3


Here's Office 2003 Compatibility Pack


Microsoft update will also find all the updates as well. The help files are a fairly large download and it won't hurt anything to ignore them.
My grammar sometimes resembles that of magnetic refrigerator poetry... Ghetto

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