# Frozen BP... safe?

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#### Justy

##### Well-Known Member
A few days ago I went out launching with my brother. This was good. He asked me to take his launch box home, since he was giving a bunch of his friends rides home. Fair 'nuff.

The days since have been cold. Very cold for this place. Today was the coldest January 4 on record in Vancouver. It hasn't been above freezing since the day I launched, and while that may not seem much to folks in the midwest, it's something unusual for us, our climate just doesn't do that (something about a warm water current from the Sea of Japan keeping the winters mild). We do scrape frost off car windows each winter, but I am unaccustomed to scraping frost off the INSIDE of my windshield. And this whole frozen lock thing is strange, too.

BUT ANYHOW... tonight I remembered that I hadn't pulled the launch box out of my car, meaning the BP motors inside are quite thoroughly frozen. There are some motors sealed in their Estes packages, and some loose.

So, my question to those who know more than I... once thawed, will they still be safe to fly?

#### Johnnie

##### Well-Known Member
Temperature cycles on BP motors can be bad over time as they will expand and contract with temp cycling...this usually causes the propellant to crack, causing motors to cato on ignition.

I have had BP motors in my garage for years where the temps will be in the 20's and 30's in the winter, and in the upper 90's during the summer months...those motors burned just fine. I would just take note of the above paragraph as something that can happen over time.

#### n3tjm

##### Papa Elf
Do not fire them if the motors are frozen. Let them warm up first. If you are a die-hard rocketeer, and launching in the winter, keep the motors in a warm place. Sudden change in temperature from cold to the heat of firing it can result in a cato.

#### BlueNinja

##### Well-Known Member
They should be okay as long as you use a gradual temperature change. Cast Iron will crack when it's hot, then you put water on it. BP pretty much does the same thing.

#### Ryan S.

##### Well-Known Member
yeah I have seen many motors cato on cold days, however I used to keep my BP motors in the cold garage all winter and then they would gradually warm up. If you are really worried you could test fire a motor and see what happens

#### gerbs4me

##### Well-Known Member
they should be ok
you should take Ryans advice and test one motor first.

#### Justy

##### Well-Known Member
Thanks everyone!
I think I will take the advice and test a motor before loading one into a rocket.

#### powderburner

##### Well-Known Member
In the old days, my mom wouldn't let me keep motors in the house, so they went into the garage (and froze in the Iowa winters). But I don't remember having problems with motor failures, at least for the old Estes A-B-C motors, even for those that had been frozen.
Now the D-13's were another matter . . .

#### astronboy

##### Well-Known Member
I have heard that extreme heat is worse than the cold... That even the temps in a locked car can cause the propellent and thus the casing to swell. Once the propellant cools, it contracts, but the casing does not. If the motor is then ignited, the gaps between the casing and the propellant can cause the propellant to burn from the edges, as well as the core. Then you have a CATO on your hands.

I myself have never stored a motor in extreme environments. (Thanks to my Engineer Dad!!) When I rediscovered my rockets in my Moms attic 2 yrs ago, the rocket engines were not there. I found them (Thankfully) still in my old ESTES starter kit flightbox under my bed in my old bedroom, safe from the unheated attic weather extremes.

I burned all of those motors before realizing that I should be saving them, but none catoed. Even the old C5-3s. I now collect vintage motors, and am cringing as I remember burning a quite a number of motors from my good sized old stash of early 1970's 'diamond boxes'

I know that I am probably jinxing myself as I write this.... but I have never experienced a CATO. Now or then.

#### powderburner

##### Well-Known Member
Originally posted by astronboy
I burned all of those motors before realizing that I should be saving them . .
astronboy, do you have any particular reason to say they should be saved?
does someone out there want them? do they have any special collector value?
I had the impression that old motors were worth pretty much what new motors cost---that no one out there was 'collecting' them. I have an box stuffed full of old motors (all the way down to 1/4A, also probably still have some D13's if you are feeling lucky) buried in the bottom of a closet. I just use them as the need pops up.

#### astronboy

##### Well-Known Member
Well powder burner.... as they say: one man's collectible is another man's weekend of motor burning.

Motor collecting is a fun, if small part of the hobby, and is mostly affordable as well. Of course, when you are talking Model Missles Rock a Chute Motors, or something like that, the price can be quite high. Generally, ESTES, Centuri, MPC, Cox, and MRC motors can be collectible to some people, but are seen just as motors to others. The prices do vary a bit depending on the motor, but generally run in the 'new motor' price range. The thing that I believe keeps the price down is 1) there were millions of these made, and 2) You have no idea how the motor has been stored over the years, so there is a loss of intrinsic value... what is the value of a rocket motor that may CATO?

Anyway, I find it to be a neat way to collect something without breaking the bank with the high kit prices found on ebay.

I have a collection of about 120 motors that range from Mid 1960's ESTES motors, to sealed 'diamond boxes' , ESTES 18mm shorties, MPC 2.25" long 13mm long burn B3s, some mid 1980's B14s, some Cox C6-4s, 'old' Quest motors with the orange/white labels, Centuri 18mm and 13mm motors, an Apogee 18mm D10, and even some ESTES E15 explode-o-matics!!

Most of the 'collection' has been culled from garage sale type boxes of old rocket stuff, or aquired by trading motors at launches. None of it is really worth much in a  sense, but I just find it neat.

For example, Quest, in its short history, has had at least 6 variations in motor labeling, packaging, and even several manufacturers. The motors are cheap, but make for a fun colection.

#### ghp3

##### Well-Known Member
A timely subject. I have been storing my motors in my Pittsburgh, PA garage. Outside temps have been as low as the single digits, but mostly in the teens and twenties, probably 15 degrees warmer in the storage area. I was planning on launching yesterday (Sunday, Jan 18) and pulled the motors out of the garage Friday evening to let them warm up. However, the first motor I flew--an Estes D12-3--CATO'ed and trashed a nice scratch built. The motor was older and purchased through an ROL auction, so I don't know it's history, and the other 5 motors I flew (all Estes Bs, Cs and one D12-0 booster) burned fine. So it's unknown if it was the cold or another factor, but I'm a bit nervous about the other Estes Ds and Es i've got.

ghp3

#### HeadHunter

##### Well-Known Member
I think it also concerns the humidity level where the motors are stored.

Say you keep them in the steamy bathroom closet, then take them out to the car, leave them overnight then fire them off at the crack of dawn after that cold night you might have a concern. BP is mildly hydroscopic, but I think you would have to line up quite a few variables to have a problem. Of course, that is what Morton Thiokol told NASA!