Updrafts, & Downdrafts

[Bigwheels]

I'm wondering if any of you gents have a proven method for doping for winds @ up, & down angles?
For instance. If you were shooting @ say 1300 yds with the wind behind you @ the FFP, but there was a blind canyon down range that caused the wind to travel uphill @ say 45* going left to right what would you dope to compensate?
BTW yes I was doing just that last week with my 300WM 208 A Max @ 2950 fps. 28.40"hg, 38*F, & light wind @ 0-2 mph from behind me.(I was doped @ 38.5 moa , & 1-1.5 moa R) But I have tried the same shot in a 8-12 mph wind, & I was being blown high.

 

[BOLTRIPPER]

Re: Updrafts, & Downdrafts

the method i use ....is polished chicken bones, sometimes a rabbits foot , when i can find it

 

[BOLTRIPPER]

Re: Updrafts, & Downdrafts

them big voids in the earth between you and the target will always goof on you....certianly in any sort of downrange wind that may bisect the bullet path....

seriously a good spotter that can call corrections is someone that is worth their weight

 

[softcock]

Re: Updrafts, & Downdrafts

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BOLTRIPPER</div><div class="ubbcode-body">them big voids in the earth between you and the target will always goof on you....certianly in any sort of downrange wind that may bisect the bullet path....

seriously a good spotter that can call corrections is someone that is worth their weight </div></div>
-
Yes it is a hell of lot more than just reading the wind direction . it's the ( Rotors ) threw terrain that is pretty hard to visualize to make calls . 'Rotors' are the Up's & Downs .

I think that shooters that have been pilots or especially Gliding or flying low-performance wings & Paragliding etc. have and overwhelming advantage to those shooters that never experienced ( Rotors ) & learned the wind and directions that cause the Up's & Down's of channeling winds flowing over different terrains .
Once you do a bunch flying close over ground terrains and actually feel the forces that pick you up & throw you around . Or then the ones that just push you down & drop you like a rock . It all becomes perfectly clear then why your bullet does not go where you make your call sometimes .
.

 

[Bluejazz]

Re: Updrafts, & Downdrafts

As far as the wind pushing up the face of a 45 degree hill, I would guess the speed, devide by 2, and subtract it from my dial up.
For instance: if the wind is going up the face of the slope at 10mph, use a full value wind call, but devide by 2 as it is at a 45 degree angle up the hill.Now subtract that amount from your dope, as the wind is lifting your bullet.
I don't get a chance to shoot much in the mountains, being a flatlander, but that is how I would approach it.

 

[longshooter]

Re: Updrafts, & Downdrafts

Being it only acts for a "moment", and not 1300 yards, you probably need only a "moment" adjustment, down.

 

[Bigwheels]

Re: Updrafts, & Downdrafts

Bluejazz, & Longshooter. I think you are on the right track. If the updraft is say about 100 yds thick nearest the target & is blowing @ 10 mph @ 45* you would want to dial for, in effect, a quartering wind hold, & subtract elevation for a lesser quartering wind. About 1/4 a full wind walue maybe?

 

[bohem]

Re: Updrafts, & Downdrafts

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bluejazz</div><div class="ubbcode-body">As far as the wind pushing up the face of a 45 degree hill, I would guess the speed, devide by 2, and subtract it from my dial up.
For instance: if the wind is going up the face of the slope at 10mph, use a full value wind call, but devide by 2 as it is at a 45 degree angle up the hill.Now subtract that amount from your dope, as the wind is lifting your bullet.
I don't get a chance to shoot much in the mountains, being a flatlander, but that is how I would approach it. </div></div>

Reasonable guess, though the sin(45*) isn't 0.5, it's 0.7071

I would suggest you try that value instead when trying it.

I was shooting that day with Bigwheels, my 260 was supposed to need 54.75 MOA but instead I was on target in 51 and change if memory serves correctly.

I'm interested in seeing how some others have approached it in a scientific manner. I was shooting this weekend at 1275 across strip mine land and had a similar experience. My approach was to look at the wind, try to read any mirage possible in those areas, then I took about 1.5 MOA off the dope at 1275 for my 208Amax & 30-06 combo. It was close, but hardly scientific.

 

[Bigwheels]

Re: Updrafts, & Downdrafts

I'll give this a try. Breaking out some reference cards, & assuming the following:
208 A Max (.649 BC), @ 2950 fps
DA of 1000' ASL.
Wind @ 10 mph with vertical component of 45* from L to R.
1300 yds.

Elevation should be 38 MOA, & full value crosswind @ 10 mph should be 7 1/4 MOA.
So if I account for the 45* angle updraft alone I should need about 5 1/4 moa windage on the dial.
Also using the 45* component for elevation as is, I would only need 36 3/4 moa.
However I'm thinking that gravity will have more influence than the wind component. So I may only want to 1/2, or even 1/4 the resulting adjustment for elevation. Leaving me with settings on my scope of 37-37 1/2 moa UP, & 5 1/4 moa Left.
Obviously not real scientific, but just thinking out loud.

 

[softcock]

Re: Updrafts, & Downdrafts

<span style="font-weight: bold">quote:
.... " is polished chicken bones, sometimes a rabbits foot ".</span>
-
It all boils-down to making 'Educated Guesses' from what you think you are visualizing in your brain happening with the winds effects @ different ranges when you bullet goes downrange .
So Even though the shooter makes a formula to do the counter-corrections of up & down rotor push & wind push & pulls . Is it not all still guessing game from visualization with the invisible wind you think you see ?
.

 

[Bigwheels]

Re: Updrafts, & Downdrafts

Correct. But isn't it the same with any wind component? We all have some formula for wind correction. I've just never heard anyone talk about a vertical component before.

 

[SPAK]

Re: Updrafts, & Downdrafts

I don't have any experience data to add but can you take your wind correction data in the horizontal plane and flip it vertical and apply it to your vertical DOPE??

For example normally, if you estimate your wind coming from 11 oclock position you would take 1/2 value wind call and apply your range appropriate windage dope.

Now if your shooting with an updraft can you apply the same principle by flipping the "windage clock" in the vertical direction? Take your wind at 1/2 or 3/4 value depending on the angle, and whatever dope you would normally apply for horizontal correction, subtract that from your elevation dope??

Does that make sense? I don't have any experience with this first hand so I can't comment on whether or not it works. Just my thought process.

 

[paphil]

Re: Updrafts, & Downdrafts








I'm new to this forum and decided it was time to chime in. I've been shooting for 50 years and got into long range about 4 years ago . I'm always interested when other people have the same problems that I have and doping the wind is my biggest shortcoming. I recently got the new DVD from Best of The West on doping the wind. It has alot of data from big names like Dave Tubbs, Lance Hopper, Steven Coff, and Bobby Hart, as well the guys from BOTW. It gives info about sloping winds, elevation changes, angle shots, temperature changes, reading mirage, flags, and vegetation. It doesen't answer all the questions but it sure gave me enough to work with for a long time. It also touches on magnus spin and how that spin differs for a left or right wind. Well worth watching if you are serious about doping the wind.

 

[Bigwheels]

Re: Updrafts, & Downdrafts

Using the horizontal wind clock to arrive at the solution I posted earlier. I think that gravity will be more influential than the updraft tho, but a downdraft may be equal to, or more than the wind clock would say. I just don't know for sure. All I know is that I have experienced this in the field shooting, & I'm trying to understand it better.

 

[Greg Langelius *]

Re: Updrafts, & Downdrafts

Yep, it must be Winter...

 

[BOLTRIPPER]

Re: Updrafts, & Downdrafts

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body">Yep, it must be Winter...</div></div>






some in TEXAS still got the ability to take a poke at shit out long......with success

 

[Bigwheels]

Re: Updrafts, & Downdrafts

I guess some of us don't have the luxury of shooting year round in 70* temps over flat ground. I do most of my shooting during winter, as summer is my busiest time of year for work. Where I have to do my shooting, hitting @ 1300 yds with any consistency IS success.
Sorry if you find my question trivial.

 

[mattj]

Re: Updrafts, & Downdrafts

Check out this article by Shawn Carlock (the .338 Edge guy).

 

[Bigwheels]

Re: Updrafts, & Downdrafts

Thanks mattj. That is what I'm looking for. I'm kind of surprised that he uses a full value for correction in an updraft. I would have thought that gravity would negate some of the correction for an updraft, & increase it for a downdraft. At least someone has tried to quantify it.

 

[Greg Langelius *]

Re: Updrafts, & Downdrafts

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Sorry if you find my question trivial. </div></div>

No, not trivial, but perhaps futile. In order to determine an adjustment value, you need to define the input values for the up/downdrafts. My concern is about how one goes about that with a good degree of accuracy.

As for it being Winter, for most of us it is a time for reflection, and for questions not unlike these.

Greg

 

[Bigwheels]

Re: Updrafts, & Downdrafts

Determining that there is a verticle component to the wind you think you "see" isn't all that hard on some days up here. Fog, snow flurries, etc. are fairly common this time of year. I believe that my question was answered by Shawn Carlok in the link mattj posted. I was on the right track, but assumed that the correction would be different for up, vs. down winds. He says it's the same as any other wind call for correction, just on the elevation dial.

 

[notquiteright]

Re: Updrafts, & Downdrafts

Wheels-
long before men decided that if they couldnt make a computer give them the answer it wasnt so, they did it the time honored way. they ran experiments and measured the result- real world, real time.

You say you shot the problem and the bullet was blown high. How much higher? Seems you had the answer before you.

Personaly I never noticed a vertical wind effect at speeds under 15MPH which means a shift greater than .5MOA. The bore angle upward of 38 minutes is about where the loft effect can start, just need more wind beneath your bullet.

Just an idea, start recording your shot data so you can build a knowledge base because as far as I know there isnt a shooter ready program to determine the verticle wind component.

Last I heard most programs say a headwind drops the strike and tail winds raise it.

Shoot and record, it isnt a fact until the paperwork is done.

 

[Bigwheels]

Re: Updrafts, & Downdrafts

I am going to start recording this stuff now that I have a data book. I hadn't really started to consider this 'till recently, as I had been thinking I was just doing something wrong. I am now confident enough in my abilities to recognise that something else was happening, & after seeing others that day were having similar results, I posted the question to see if others with more experience had done any work on it. I have learned that Shawn Carlock had, & will be using this info next time out to see if it jives with what I see.

 

[memilanuk]

Re: Updrafts, & Downdrafts

Even on (somewhat) flat KD ranges, up & down drafts can ruin your day in a hurry. Usually wind coming down over the top of the impact berm pushing the shot high, or wind sneaking up a draw to between the firing line and the target to push a shot high. The problem with trying to quantify it is its incredibly difficult (at least for me) to really see it and put a value to. Is what caused your 9th shot to drop out of the 10 ring a down draft, or were you riding an up draft for the first string and got bit by the return to 'normal' conditions? About the best I've been able to do is watch the target and the conditions when others are shooting and try to identify the 'normal' condition and simply hold up when they get unstable. Some times (Fullbore) you don't have that luxury and an educated guess of holding 'about this much' high or low is all you can do.

 

[Bigwheels]

Re: Updrafts, & Downdrafts

True enough. I now realise that some of my confusing results from days now long ago were probably a result of this. I do the vast majority of my shooting alone, & therefor am trying to quantify as much as I possibly can to increase my hit percentage. Especially now days when money for practice rounds is scarce. I hate to waste money on misses.

 

[Greg Langelius *]

Re: Updrafts, & Downdrafts

All I am trying to convey is that the shooter can put too much faith in computational solutions. There is always more going on along the trajectory than nearly all of us can quantify and include in the computation. Monte's comments mirror my own views, but he has a lot more practical experience in the matter than I ever could claim.

Greg

 

[JC Steel]

Re: Updrafts, & Downdrafts

I think bigwheels bullet was hitting about 6 moa high. Is that correct bigs? I know it was super high and hard to spot because it was in the bushes way above the target. After we figured it out bigs was able to get consecutive hits.

 

[badbot]

Re: Updrafts, & Downdrafts

I remember seeing wind flags that were able to show vertical somewhere.

found it,
http://benchrest.com/class/index.php?a=2&b=259

 

[Bigwheels]

Re: Updrafts, & Downdrafts

Yes. At first it was hitting a LOT high, but I soon realised that I was using dope for the wrong bullet. Once I figured that out I think it was more like 1-1.5 moa high.

 

[JTG]

Re: Updrafts, & Downdrafts

Count on a second round hit.

 

[kocoa88]

Re: Updrafts, & Downdrafts

Bigwheels,

For what it’s worth, I think Monte is spot on. SWAGing the vertical wind especially over open terrain like you are shooting takes some getting used to... And then, it is never 100%. Keeping as accurate data as you can for your weapon system will be your best bet over time.

The diagram in Sean’s article is ok but it doesn't paint the complete picture. Approx every 10 feet of elevation from ground level up the wind changes speed. (Of course ground level is relative to your position and the position of the target in which you intend to engage.) This is due to ground temp, air temp, hi and low pressures, micro terrain and other factors that can go on and on. Reading the terrain and determining how the wind is moving over the terrain will give you a leg up for the most part. The best way to describe it is how water moves over rocks in a stream. If you think about how water moves over rocks in a stream you will have a good idea how the wind works while it is moving over and through draws, fingers and valleys. But, you must first establish the general wind direction.

Reading the conditions that Sean described in his article i.e. leaves, grass and the like is a good indicator but are not a constant. Contrary to popular belief grass, leaves and other biological indicators are subject to collecting moisture. Therefore, a dry leaf will act differently from a wet or green leaf. Temperature plays a part in that as well. Colder temps will lock in moisture and will not allow the plant to act as it would in warmer temps. I’m sure you can see where I’m going with this. Again, accurate data will get you through things like this.

Without writing a book on it here, your best bet again, is to keep accurate data for the conditions that you shoot in. The more problems that your terrain dictates for your firing solution, the more finite you need to get in recording your data. PDA's and other electronic gadgets are great for starting data but there are none out there with the technology needed to give you accurate data for the situations you describe. I know, I won't make many fans with that comment but it is what it is.

I surely don’t have all the answers but I can’t emphasize enough about keeping accurate data for each weapon. Maybe I’ll see you at the Steel Challenge in Kettle, Falls. If so, we can talk about it further.

 

[Bigwheels]

Re: Updrafts, & Downdrafts

Thanks kocoa88. I'm looking in to it more carefully now that I've figured out what it was. And I can't promise I can make it out for the shoot this year, but I'm going to try.

 

[bigngreen]

Re: Updrafts, & Downdrafts

During an elk hunt this last season I got in a spot that I could visually see the down draft due to a light snow and I took some time to put some notes down for that particular spot. It is quite common effect in the area I elk hunt due to the lay of the land and the prevailing wind, these are fairly predictable I think as it's acting on an up slope not just tumbling over the ground. One thing I noted was that I could make a better wind call bases on the sound of the wind in the trees as apposed to the movement. I applied that to a couple shots at 803 and 1093yrds and found that in a 5 MPH wind at the ground if I could hear the wind higher up in the trees I added 2.5 MPH to my reading on the ground and the dope was spot on. I think it would have been a better reflection of what was going on to use 0-300yrds 5mph and 800-target at 5MPH with the middle much higher, but adding half of full value seems to have worked out over all but I haven't done it more than a few times, it may fall apart later.
I'm trying to take my notes on the down draft and work them out so I can us Loadbase to give me a good prediction, this one spot that has an almost constant down draft that I would have to shoot through at about the 850ish yrds to 1100yrds that ends in dead air and starts in a strong cross wind in a saddle, it's a little intense but the spot is killer for elk feeding out, for now I close down the distance to 836 yrds and shoot up the bowl that has is almost dead compared to the surrounding area.
So far my solution is full value from gun to 850 then form 850 to 1100 also full value but toggling off to see what number that range contributes to the dope then adding it's value to my vertical and leaving that with a much lower value for the wind dope since the air is slammed down by the higher wind flow that does not drop into the canyon but move like a blanket over the area. I plan on shooting this out till I get it or get over it, but the down drafts have really intrigued me, for now not shooting elk though them but trying to get a grip on it if possible!