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For all "COLD weather " fliers any problems with deployment at sub zero?

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blackjack2564

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I know a lot of you fly during winter months at temperatures near 32 degrees and lower.

Most all altimeters I've researched show the bottom range of use at 0 centigrade or 32 Fahrenheit.

Are you experiencing any related problems flying at such temperatures?
Are special precautions needed?
Or does everything just seem to work fine?
 

kandsrockets

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Jim this is a great subject. I have been doing some testing on this with a PF Hialt45 and a Duracell 9V battery. Being that it has been anywhere from 20 degrees to -15 degrees F here I figured this would be a good time to do some testing since I would like to do some flying in the winter. I started by doing all my prep work in my vehicle with the heater on just like I would be at the field. First I wrapped my battery with self adhesive foam (the thin stuff you can get at michaels) and then wrapped it with electrical tape, this gives it a little insulation from the cold. After having everything prep, I took the rocket out to the yard and sat it on my stands. I then went through my check list just like I was going to fly. After the alt was armed I waited 15 minutes (figuring waiting to be launched and flight) I then used my shop vac to set off the charges. Both went off with no problems. My starting voltage was 9.4V and after getting back to the vehicle it was 8.9V. One thing I did find is that after getting everything back in the warm things started to get moister on alt and battery, so this might be a problem if you want to fly it again. I would recommend using another alt and battery if you want to fly again that day or give it time for the moister to dry up befroe using the same alt. I did this test 9 times and got close to the same results with just the voltage being different a tenth or 2.
 
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blackjack2564

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I hadn't even given those issues a thought. Your experiment gives rise to that also.
I was thinking in terms of the sensors being used [particularly the baro] reading out, and/or functioning properly in the cold. And downloading data in these extreme conditions, will it corrupt?

I have been told some use the small size glove warmers to prolong battery life, by putting them in the bay, and keeping the temp. up.

My understanding from reading only is: the altimeter should be allowed to get to the ambient flying temperature, to prevent the condensation you speak of, unless some sort of heat is provided during the flight.

Maybe Adrian can shed some light on this issue when he shows up.
 
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kandsrockets

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Jim I did not find a problem with moister going from the heat to the cold, I had it the other way. The hand warmer idea sound like something I will have to try. I want to build a test bay that I can put some temp sensors in it to see what is going on. I hope to try and work on this coming week and dop some testing next weekend.
 

rstaff3

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I have a hard time deploying myself in cold weather....so I never have a parachute deployment problem :(
 

Fred22

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Before this winter I have regularily fired rockets at -40C. This year unfortunately I have been too busy but hope to start going hard again in February. You have to fire them quick or the chute freezes I think. The other problem is warm tube wet snow can soften the MBT. I have no idea about electronics but I can tell you battery life is zip in -20 to -40 if that helps. Also moisture forms on cameras if brought in from the cold so I put them in a bag and let them come up to room temp graudually to avoid condensation problems.
Cheers
fred
 

rstaff3

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Fred, so do you ever get to fly above freezing?:eek:
 

cjl

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I've never had a problem, but I've also never flown electronics below about 30F. I've done non-electronic deploy ones down to 0F and below though (only a few times) without a problem.

Of course, I don't have anything on Fred for that...
 

MarkII

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No problem with deployment, because I don't often go out to fly at those temps. When I do launch something, it is usually a saucer-style rocket, an odd-roc or a Micromaxx rocket. Deployment of a recovery system is not usually an issue with any of those, but that's not the reason that I choose them for cold-weather flying. I go with those types of rockets is because I don't have to chase them very far! ;) (I generally move my launch site to my driveway, about 30 feet from my back door, when the temp. is in that range... :rolleyes: ) We do have a rocketry "off-season" around here, usually running from October to May.

Mark \\.
 
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Fred22

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No problem with deployment, because I don't often go out to fly at those temps. When I do launch something, it is usually a saucer-style rocket, an odd-roc or a Micromaxx rocket. Deployment of a recovery system is not usually an issue with any of those, but that's not the reason that I choose them for cold-weather flying. I go with those types of rockets is because I don't have to chase them very far! ;) (I generally move my launch site to my driveway, about 30 feet from my back door, when the temp. is in that range... :rolleyes: ) We do have a rocketry "off-season" around here, usually running from October to May.

Mark \\.
All very sensible things to do. I have launched a five engine sat V on Christmas day in -20C as I lack common sence :)

Cheers
fred
 

Handeman

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No problem with deployment, because I don't often go out to fly at those temps. When I do launch something, it is usually a saucer-style rocket, an odd-roc or a Micromaxx rocket. Deployment of a recovery system is not usually an issue with any of those, but that's not the reason that I choose them for cold-weather flying. I go with those types of rockets is because I don't have to chase them very far! ;) (I generally move my launch site to my driveway, about 30 feet from my back door, when the temp. is in that range... :rolleyes: ) We do have a rocketry "off-season" around here, usually running from October to May.

Mark \\.

Here in VA, it just the opposite, we have access to the field when the crops aren't in, so we fly Oct/Nov. to Apr/May. Had the launch last weekend postponed because of cold, it was going to be in the high 20s. With that said, I don't think I've flown anything below freezing.
 

MarkII

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Here in VA, it just the opposite, we have access to the field when the crops aren't in, so we fly Oct/Nov. to Apr/May. Had the launch last weekend postponed because of cold, it was going to be in the high 20s. With that said, I don't think I've flown anything below freezing.
I'm going to make a wild guess that your fields aren't buried under several feet of snow during those months... :D

I should mention that because my area is so heavily forested, winter offers us access to some of the largest open fields that can be had anywhere around here, fields that are not available any other time of the year - the frozen surfaces of lakes! It's not an option that I have explored much yet, because I haven't found enough people who were crazy enough about flying rockets to go out to do it with, and I don't want to go running around out on the ice by myself.

Mark \\.
 
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CharlaineC

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I fly in the winter summer spring and fall. winter has its issues but this is what i do to keep flying.

1. batterys kept warm by chargng them the night befor then keeping them in the inner pocket to my coat.

2. motors kept in coat to keep warm.

3. talc on chuts and packed right before launch.

that kept me flying in the coldest weather
 

blackjack2564

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Somewhere along the line this thread has taken a left turn. I mainly interested in cold weather influences on ALTIMETERS in cold weather, and their components.

Basically their sensors are rated from 0 and above, I know there are lots of fliers up north that fly in sub zero conditions, and wondered what if any problems they have, and how they deal with it. [altimeters functioning properly]
 

MarkII

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Lousy skiing then too :) :lol:
I have heard that the outdoor rinks get pretty wet, too. (BTW, we still do ski-jumping and freestyle here during the summer. :cool: )

Back on topic, Fred makes a good point about battery output being zip when you get into the deep freeze. (That's why you store them in the freezer to preserve them.) As I understand it, basically, the chemical process comes to a near halt. Yet high-alt research rockets have electrical systems and avionics that function in the stratosphere, where it is not exactly balmy (at least, by any standards outside of Manitoba or Alberta). So how do they do it? Capacitors? Super-caps? On-board heaters? Plutonium sources? :confused:

Mark \\.
 

Adrian A

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I think that the safe operating temperature for each altimeter will vary, so test it in the cold if at all possible before counting on it working in the cold. And keeping the battery happy is very important, because cold is great for increasing the internal battery resistance, which can drastically cut down on the available current for your charge. When I have gotten the Parrot's Li-ion batteries too cold (<32F) during calibrations, I have run into problems with battery power.

Cold can also affect the altimeter calibration. If you have a recording altimeter, you can test the temperature sensitivity with a simulated flight that goes from room temperature to the freezer and back again. The altimeter should report a flat altitude despite the temperature changes. If the freezer portion reports large changes in altitude compared to room temperature, then don't expect your cold flight altitudes to be accurate either (though it should still be able to detect apogee o.k.)

Now that it's nice and cold again in Denver, I should do another test, leaving a Parrot with its battery outside overnight and then doing a simulated flight. When I did this with an earlier version with ambient air temperatures in the 20s, the Parrot seemed to work fine, and there was minimal effect on the pressure reading when I brought it inside and warmed it up.
 

dlb

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Hey Jim

YES
I did live in Michigan till 1999, during that time I flew in very cold weather, up to -22 one time.
and YES I had (2) failures, one was a complete loss, but the other had a timer relay I used ( no rocketry timer back then ) Saved me AsP, only to find out the expencive alt (Emmanuelle altimeter)(fogive the spelling) had fail due to the use of commercial grade electronic and maybe the battery a little ( it was pre-warmed). I did have to warm up the unit in my car before it would work again.

after that, I did use a wirewound resistor across the top of the micro ( 68hc11 ) to heat it up, low and behold it worked. some one told me that they used small hand warmer packs to due the same on batteries.

may just maybe using full MIL SPEC parts may help out here, but the cost of that Altimeter will climb a bit.

mostly use now days seem to be MicroChip "PIC" processors and they do have MIL SPEC parts.

Two Cents, ok a 1.5 cents:)
 
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troj

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Something else to factor in is what the temperature does to the battery. You need to keep the battery warm throughout the entire flight.

Modifying the electronics bay, or figuring out a way to keep one of those little air-activated hand warmers around the battery might help a bit.

-Kevin
 

H_Rocket

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Somewhere along the line this thread has taken a left turn. I mainly interested in cold weather influences on ALTIMETERS in cold weather, and their components.

Basically their sensors are rated from 0 and above, I know there are lots of fliers up north that fly in sub zero conditions, and wondered what if any problems they have, and how they deal with it. [altimeters functioning properly]
Jim - Speaking as an attendee of the Great St Valentine's Day Rocket Massacre (SVDRM) of 2007 (Temps around 10 degrees) we had nearly 100% electronics failure and we came the conclusion that all were based on temperature. Our thoughts were that all of the failures were battery related and held a great discussion on the merits and methodologies of altimeter functionality in cold weather.

The barometric sensor on an altimeter is essentially a membrane that may get stiff when exposed to extreme cold. At the SVDRM we had failures in barometer based systems (RRC2), timers (EFD1), and accelerometers (ARTS). Considering that some of those are entirely solid state we came to the conclusion that it was batteries, not the circuitry.

We had great discussion on the matter with the following ideas:

Keep the electronics warm (in the car or whatever) until the last minute - bad idea spelled condensation

Come up with a way to warm the avionics bay - we considered all sorts of ideas.
  • Kapton encapsulated heating elements were way too expensive and needed dedicated power.
  • Iron Oxide based heat packs - we talked this through, however controlling the head seemed problematic.

I think we just decided - if it's that cold, use motor ejection or just stay inside, have hot cocoa, and tell lies about that special flight.


Oh yeah - 32 degrees is not a problem, single digits is where we experienced the difficulty.
 
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blackjack2564

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Thanks Al....this is the kind of feedback I was looking for. The limits of usage. So evidently it seems to be all battery related then, not the electronics themselves. But I'm still wondering though, all specs on what I have seen, limit the bottom end of sensors to 32 degrees.
Must just be a little leeway there.
I understood Adrians test explanation. But unless you have access to a very accurate vacuum chamber , don't know how you can reproduce the same test at the same simmed altitude repeatedly, by pulling the vacuum. I would like to try that with my R-das.
 
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Adrian A

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I understood Adrians test explanation. But unless you have access to a very accurate vacuum chamber , don't know how you can reproduce the same test at the same simmed altitude repeatedly, by pulling the vacuum. I would like to try that with my R-das.
I think you can test the temperature sensitivity without any sort of vacuum, as long as you can trigger a simulated liftoff, and your altimeter is one that allows you to download flight data. With the altimeter at ambient pressure, just change its temperature. In the recorded data you should see no change in the altitude.
 
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