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Yaw Drift
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31432 167 2015-1-6
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cory
lvl.1
United States
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Whatever I do I cannot get it to stop drifting when I yaw in GPS mode. I've calibrated the compass, I've degaussed the compass, I"ve done advanced calibration 20 miles from society. The craft never flies as well as it did out of the box.

Out of the box I could yaw in 10mph without any drift. Now after messing with the IMU it seems I always drift about 10 feet to the right when the craft is facing forward in GPS mode... If I go to atti mode, the drift is ALOT less.

When I yaw in GPS mode, it drifts 10 feet away, then it seems GPS kicks in and it starts to fly home.... It seems yawing is disabling the gps.. I can fly the craft around in GPS mode by yawing to the left and right. As soon as I stop yawing, about 3 seconds later the craft starts to fly back to the last GPS spot...

Another issue I see is when I yaw, and I try to fight the drift, the craft actually WANTS to go into the direction of the drift... Like its fighting my stick movement and has a mission to complete this drift.... 2 seconds later GPS seems to kick in and it flies back..

Its very annoying... I have video out of the box yawing while it holds its position... Anyone have a fix for this? I've never crashed. it all seem to start happening once I calibrated the IMU. Since then I've calibrated.




I'm out of options, this thing was a dream to fly and yaw around, but now its grounded because of its instability. If I cant fix this, I'll have a cheap phantom vision + for sale soon.
2015-1-6
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Jamie Hellmich
Second Officer

United States
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Cory, I'm with you brother.
I have this issue as well.  It should pirouette on it's axis as my other quad copters do, and I'm quit certain it did the first morning I flew it.  I would have noticed it then.   It does it in GPS mode, and in ATTI mode.  A painfully slow yaw seems to help a bit, or a super fast one.

It is very disconcerting as it will drift up to 10 to 15 feet in a 180° turn either direction with no wind.  In GPS it will eventually return to the position it held at the start of the spin, but the Phantom seems to "get angry" as Cory has described when I try to correct the movement or force it back to position.

In a ATTI it will just kinda keep drifting right and back until manually corrected, in a CCW/Left 180.  Opposite for a CW/right yaw.

I have performed countless compass calibrations, IMU calibrations, re-installing firmware, prop changes, etc...  I keep thinking it's something I've done, or not done correctly.  I've been flying RC planes and copters for many years, and am an AMA instructor, so I'm not new to the hobby, and have some technical experience with the radios and aircraft.

It's been my thought to send it back to B&H because of this, and I have until the end of January with their extended Holidays Return Policy.  It makes me very nervous to fly within 20' of anything, and I had dreams of nice video sliding through the trees and skirting about river and creek shore lines, etc... But not when I can't rotate and pan the camera without drifting out of position.

So Cory, I'm not trying to hijack your thread here, I do have the same condition and wish to ask the others on the forum here...

Too All...Does your Phantom 2 Vision + pirouette in place in a hover, or does it wander or drift as Cory and I have described?

Jamie


2015-1-6
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rod
First Officer

New Zealand
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Hi Jamie, mine spins on its virtual axis as if it were on a pole!  Nothing special with my rig but usually have the luxury of 10-12 sats.(I am in New Zealand)  I must say I have had no problems at all (other than a self inflicted dodgy compass calibration!) since new.  Sorry Cory I'm no help on this one , just answering Jamie's question.
Cheers!
Rod
2015-1-6
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Jamie Hellmich
Second Officer

United States
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rod@voxvideopro Posted at 2015-1-7 11:38
Hi Jamie, mine spins on its virtual axis as if it were on a pole!  Nothing special with my rig but u ...

Thanks for the response Rod.  I've been hanging on trying and hoping to find something with Google and forum searches, but can't seem to find any solution.  Pretty much stumped at this point.

I'm like Cory, and think it has something to do with my first IMU calibration or firmware update the morning after I first flew it.  Later that afternoon after "messing with it" in Assistant, I flew it and immediately noticed the drift.

Jamie
2015-1-6
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dutch445
lvl.2

United States
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my v3 does the same thing, posted on another forum and it seems pretty common place,
and nobody can really answer why it happens,

Rod is yours a vision plus v3?
2015-1-6
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Pmcdn2014
lvl.2

United States
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When I had my vision I experienced yaw drift.  I agree, it's very annoying.  I reset the compass and recalibrated like this video demonstrates and it worked for me.  

http://vimeo.com/103634940

Good luck!
2015-1-6
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rod
First Officer

New Zealand
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dutch445@gmail. Posted at 2015-1-7 11:52
my v3 does the same thing, posted on another forum and it seems pretty common place,
and nobody can  ...

Hi Dutch, no it is a PV2+ with the controller that has neither the wheel or the lever on the back.
Rod
2015-1-6
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Jamie Hellmich
Second Officer

United States
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Pmcdn2014 Posted at 2015-1-7 12:03
When I had my vision I experienced yaw drift.  I agree, it's very annoying.  I reset the compass and ...

My compass numbers are good, with the MOD always around 1450 to 1550.  I've calibrated it numerous times, at numerous locations.
2015-1-7
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cory
lvl.1
United States
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Thanks for the responses guys, lets keep this thread alive.... There are 50 threads on the Internet that die without a fix of this issue.

MY buddy has the same exact Phantom vision 2 + bought from the same company. He's never done any IMU calibration and his spins on a dime. Mine on the other hand will drift 10-15 feet even when yawing slow.

Pmcdn2014 thanks for that video. Thats callled degausing the compass. I've done that a few times without any luck.

I also have 11 sats down here in Florida. Its not a sat or compass issue. The issue seems to be the GPS disabling, or the GPS postition is skewing when yawing causing the craft to want to drift. Like I said above, if I try to hold the craft in position while yawing, its FIGHTING me to drift. This tells me the flight controller is WANTING to drift in that direction. If it was a simple level issue or compass issue, then when I hold the craft it should just spin in place while I hold it..... However it seems to be WANTING to move to the drift position before realizing its screwed up and drifts back...

It only seems to be getting worse after each calibration.
2015-1-7
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cory
lvl.1
United States
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ps, I've also been flying Heli's and planes for 20 years. The Phantom acts just like my Trex 450 without a GPS when yawing. I'm not new to this game, there is a problem here.

I posted on DJI's page and they linked me to a fan created video to adjust gains. So it seems they dont know either.
2015-1-7
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Jamie Hellmich
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United States
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As it does this in ATTI mode as well, I'm not sure it is just GPS related.  Gains have no apparent affect based on my trials adjusting.

I have been considering the "Mounting" values adjustments for IMU and GPS unit location in Assistant "Basic" settings.  A possible software balance/CG issue?  My values are all 0's, as are apparently the Defaults.  I'm grasping for straws.
2015-1-7
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cory
lvl.1
United States
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Jamie, that was my next move as well...I've also adjusted gains without success. However when I change the value of the mount location, it just changes back to 0. It doesnt allow me to change it within the software.

Mine certainly drifts in ATTI mode, but if I stop the craft it doesnt fight me to go into a drift. In GPS mode, its like it fights me to drift, then returns back to the original spot.

I'm going to take some video tonight to show everyone.

Question for someone who's phantom spins like its on a pole... Can you connect your craft to the DJI software and tell me the mounting location values, as well as your gain values? Please make sure you have a version 3 plus..
2015-1-7
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cory
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United States
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I know the GPS is dead center, but open crafts, the Main Controller is off center a cm or two. Perhaps when we did the IMU configuration, it changed the to the 0,0,0 mount location, when it should have the Y axis off my a CM or two....
2015-1-7
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cory
lvl.1
United States
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Here is the first flight I took with my craft, around the 50 second mark you can see me yawing without any drift. I will take another video when I get home, in the same location so you can see what type of drift it has now... Its definitely some kind of software issue.

2015-1-7
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Jamie Hellmich
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United States
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cory@movecost.c Posted at 2015-1-7 23:39
Jamie, that was my next move as well...I've also adjusted gains without success. However when I chan ...

When you typed in the value for Location, did you hit the "ENTER" key on your keyboard?  I know you have to do that to change the Gains.
2015-1-7
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birdfolk
lvl.4

United States
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When shut off, do all the props spin with the same degree of ease and consistency?
2015-1-7
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cory
lvl.1
United States
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Jamie, yes I hit enter after the values. after I hit enter it defaulted back to 0.

Birdfolk, yes all the props spin up and stop at the exact same time.
2015-1-7
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Jamie Hellmich
Second Officer

United States
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Come on guys, only 3 people have responded to my query.  How about you regulars?

Too All...Does your Phantom 2 Vision + (or other Phantom 2 model) pirouette (yaw spin) in place in a hover, or does it wander or drift as Cory and I have described?

I'd kind of like to know if this is just the nature of the beast and common to the model, or if I have a problem.  I know I do not like the way it behaves, and is it just something I'll have to live with?

Jamie

2015-1-7
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gnixon2015
First Officer

United States
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P2V (no plus), no yaw drift (10 flights only 1 compass calibration, no crashes)
2015-1-7
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cory
lvl.1
United States
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I just went to a buddies house.. He has a Vision Plus V2... Spins on a dime, no drift....

I put mine in the air, and it started moving backwards immediately.... Then went back to its take off position... I did a yaw, and it flew 20 feet off course.

I think I'll just return this, seems there is no fix, and all DJI did was point me to a forum post about gains. Seems to be a defect, hopefully UAV direct will refund my cash... This thing is no longer fun to fly, and its more of a disapointment. I've spent way too much time (20 hours) trying to get this thing to fly like it did out of the box, I'm done with the disapointment.
2015-1-7
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Jamie Hellmich
Second Officer

United States
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After work I even tried putting lead weights I use to balance my planes on the different motor arms to see if changing the physical CG affected it. After numerous flights with different weight locations and amounts, it did not once affect the wandering during a pirouette.

In fact, the Phantom maintained perfect level hover in GPS or ATTI mode no matter where I put the weight.  It corrects for CG very well.  So I've eliminated it being due to a physical CG problem.

I am considering returning mine as well, if I can't figure this out in the next week or so.
2015-1-7
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Jamie Hellmich
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United States
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gnixon2015 Posted at 2015-1-8 08:09
P2V (no plus), no yaw drift (10 flights only 1 compass calibration, no crashes)

Thanks for your response.

Jamie
2015-1-7
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cory
lvl.1
United States
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I'm running an IMU calibration right now with a stack of papers under the front, so its unlevel as hell.. I want to see if it has any effect.... Gotta wait for the MC to cool down first.

I've tried adjusting the mounting location of the GPS...The values dont seem to stick after a restart, but even changing the GPS 10 cm off, it made no difference... Its like the gains and mounting locations are just for looks. They dont do anything.
2015-1-7
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cory
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United States
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I believe this software is uploading values to the V3's that are causing the IMU to become out of wack. They come from DJI with the IMU perfect. Perhaps even the MC is offset, but when loading the software it resets things to zero causing the craft to be out of balance, even when the software thinks its in balance. I've even tried the different verions of the software, 3.6 vs 3.4, none of them want to hold the GPS offset values. And forget about changing the IMU offset, they are hardcoded to zero.
ps. I'm a software programmer, so I have some unique testing.
2015-1-7
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cory
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OK so after calibrating the IMU with a stack of papers under the front definitely produced some results. It drifts way more to the front than it did. It made it way worse, so now I'm waiting for the MC to cool down so I can do another calibration with the papers on the back end instead of the front.

Now I'm starting to think that even though the craft is on level ground, the IMU inside is not level.... Need to find the exact tilt to calibrate the V3 on, and perhaps I can eliminate this... Hopefully have an update here in 15 min.
2015-1-7
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gnixon2015
First Officer

United States
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that is some awesome info cory.  keep us posted, very interested how your tests come out.
2015-1-7
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Jamie Hellmich
Second Officer

United States
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cory@movecost.c Posted at 2015-1-8 10:24
OK so after calibrating the IMU with a stack of papers under the front definitely produced some resu ...

Good deal man, I was thinking about that earlier today.  Awesome.
I've been wanting to look under the hood to make sure everything is where it's supposed to be, but afraid to cut the decals voiding any warranty or return ability.



2015-1-7
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cory
lvl.1
United States
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Ok I think I got it... Definitely a balance issue. now my drift is reversed. I think this is going to be a pain staking trial and error to balance this thing perfect so it spins on a dime.... Apparently v3's are coming from the factory pre balanced. When us end users are redoing the IMU, its not 100% balanced like it was from DJI... Perhaps the v3's are more sensetive..

The most important thing we have to do is do the IMU calibration in the same exact spot, facing the same exact way each time... Calibrate, and go fly... If it flys to one side, raise that side with a single piece of paper and recalibrate. Fly again, I'm going to spend another 5 hours doing this over and over to see if I can fix the issue.

my results are definitely promising... at least I can manipulate the drift now.
2015-1-7
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Jamie Hellmich
Second Officer

United States
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how much did you shim the rear during cal to make it go opposite?
I will start experimenting with this tomorrow afternoon.
2015-1-7
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cory
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Well F me.... Mine is spinning on a dime now.... I lucked out and stuck the right about of papers under to balance her... She spins on her axis on a dime now.

For anyone else having issues, you need to find out which way its drifting... You need to raise the opposite side of the drift with a few pieces of paper. Re-calibrate and test your flight. If it still drift to the same side, re-calibrate it and raise the opposite side more. If it drifts too much to the other side, then remove a piece of paper.. The MOST IMPORTANT THING IS TO ALWAYS PLACE YOUR CRAFT IN THE SAME EXACT SPOT, AND FACING THE SAME DIRECTION WHEN DOING THE IMU... Manipulate the level with peices of paper...

These IMU's need to be dead center to the millimeter.
Hopefully it helps the many people out there who had my issue. Mark this one solved.
2015-1-7
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cory
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United States
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Jamie, mine took about 10 pieces of paper under the back end to fix the drift... Mine was drifting dead forward. So I placed the paper on the back end of the bird. Its quite unlevel when doing the calibration, but flying is a dream now.. I'm soooooooo happy.

If you're does a drift to the front and center, turn the bird a little so you get a drift to the front or back. This will make it easier to shim it up with paper... I would think it would be harder to fix a front left drift... Its better to turn the bird and calibrate till you get a solid forward or reverse drift. From there, shim it up with some paper on the front or back, opposite of the drift.
2015-1-7
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Jamie Hellmich
Second Officer

United States
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As I yawed CCW with the back of the Phantom to me, it would drift to it's back and right on a 180° spin.  I will try just shimming the front first based on your statement.

Thanks again Cory.
2015-1-7
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cory
lvl.1
United States
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Yup, mine would do the same thing... If it drifts to the back and the right, put the craft in the same exact spot, but turn it to the left and re-calibrate it.... It should now fly directly backwards when yawing... After that now you can shim up the FRONT, since its drifting to the back.... Remember, shim the opposite side of the drift.

Good luck, its not a defective craft, its perhaps a slight variation on how the IMU is setting inside. Or perhaps my floor isnt as level as I thought.

Anyhow, this will definitely solve the first problem. But it takes alot of trial and error... And dont ever touch IMU calibration again..lol
2015-1-7
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Jamie Hellmich
Second Officer

United States
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Yeah, I'm not sure how level my desk is, but nothing rolls off and it's pretty massive.  I'll put a level on it.  If this does work, I may go ahead and look inside to see if the IMU is out of kilter or loose.

Funny though, I've done the IMU cal a couple of other places as well, with the same result.  Maybe the surfaces were actually all level, and this shimming will do it.

10-4 on leaving the calibration alone once it's good.  Later.
2015-1-7
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cory
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United States
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Jamie, my desk is level as well..I leveled it with a bubble level. I believe the V3's IMU are not 100% level inside the craft which is why when we do the IMU they drift...

My craft would fly 20 feet when yawing before this fix... I'm pretty sure we all have the same issue... Shimming is definitely the answer.  I just got back from flying outside, and I can spin the craft like its on a pole, just like these V2 owners are saying..

Its great now, and most importantly, I'll be able to sleep tonight..lol...Good luck, and I hope you solve your issue... Its was definitly disapointing, but now I'm fully confident that its fixed...
2015-1-7
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Jamie Hellmich
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United States
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Good deal, I know EXACTLY how you must be feeling.  I can't wait until tomorrow afternoon to work on it.

I'm in the Ormond Beach/Daytona area, and work down at the Space Center.  You anywhere nearby?
2015-1-7
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cory
lvl.1
United States
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I'm in Boca! 3 hours south
2015-1-7
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rod
First Officer

New Zealand
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Gerry1124 Posted at 2015-1-8 11:50
Can I send you guys some of this stuff?  We got it all last night.

Hi Gerry, no it wouldn't survive here in New Zealand at the moment, we have seen 30C this week!
(Mid summer of course), but if you can hang on to it until August--------
Cheers!
Rod
2015-1-7
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Jamie Hellmich
Second Officer

United States
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Gerry1124 Posted at 2015-1-8 11:50
Can I send you guys some of this stuff?  We got it all last night.

Hey Gerry,

Bring it on, we don't get that around here.  That might be fun to play in... for a couple of hours... then you can have it back.  

Jamie
2015-1-8
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cory
lvl.1
United States
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ITs 58 this morning and I have the heat on and 3 layers.
2015-1-8
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