Winter frustration and bad Estes motors

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

mbecks

Well-Known Member
Joined
Nov 6, 2015
Messages
420
Reaction score
17
Location
Canada
Just want to vent some frustration about rocketry in a cold climate. Where I live its been consistently -20c to -25c (-4f to -13f). I finally got a project finished and went to launch it even though it was cold out and hopefully get some footage for a Youtube channel I want to start. Two of the cameras froze and shut off with out me noticing making the only footage I got coming from a cell phone. On top of that I bought a pack of E12 motors and two of them blew up, the second one blowing apart my motor mount. Is it all Estes E motors that suck and fail consistently. I thought it was just the E9s but man am I disappointed those E12s are $10 a pop where I live so having them just blow up feels like such a waste of time and money. Does anyone else live in a cold climate and have issues with rocketry? Does the cold effect the rocket engines?

rockets blowing up.
[video=youtube;Du85yZFO8pU]https://www.youtube.com/watch?v=Du85yZFO8pU[/video]
 
Cold temperatures cause BP to shrink and crack. Estes motors should always be stored indoors and relatively dry. Temperature cycling multiple times is even worse. Absorbing moisture over time adds to the problem. The E12's have a larger amount of BP which makes the thermal issues worse... stress from cold increases with length and diameter.

When I lived in the Northeast US, I would keep the BP motors in my pocket until the last minute when launching in the Winter.

Composite propellant with its rubbery binder is not as susceptible to cold/shrinkage issues. Some formulas can absorb moisture (certain effects chemicals) and swell over time.
 
From what I hear from a lot of sources is exactly what jsdemar said. BP motors don't do well in very cold temps. The problem is that the rate of shrinkage of the BP and the outer casing is not exactly the same. The cracks that form allow the flame to propagate quicker than the motor is designed for, thus causing an overpressure situation and rocket confetti.
 
living in Canada I doubt the motors are kept heated during transport into Canada. I feel like rocketry in Canada in the winter may just be a waste of time. Man oh Man what else am I going to do with my winter. The rocket sled made it bearable. Guess I can try staging more rather then going bigger.
 
living in Canada I doubt the motors are kept heated during transport into Canada. I feel like rocketry in Canada in the winter may just be a waste of time. Man oh Man what else am I going to do with my winter. The rocket sled made it bearable. Guess I can try staging more rather then going bigger.

I usually buy motors during the summer and bring them inside during the cold months (I’m in Montana so my temperature range is similar to yours.
Perhaps I’ve been lucky. I haven’t had BP catos in spite of the fact that I have at times forgotten to bring the motors in from my cargo trailer. Perhaps it’s possible that the slower heating and cooling isn’t as hard on them; I don’t know.
For the most part we don’t fly during the winter. The exception revolves around TARC. Practice flights have to happen during the winter months. I would recommend the following:
Order your motors during the summer. Bring them in a cooler or a surplus ammo box lined with styrofoam when you go out to fly in the winter months.


Steve Shannon
 
Last edited:
Thanks for the advice Steve, guess I’ll stock up this summer and keep them in my house. I just went out and followed the advice of keeping the motor in my pocket and behold it was a successfull yet slightly boring launch. Way better then it blowing up though.
 
Can you get some Aerotech or CTI MPR E-F motors in Canada? They are generally unregulated in US outside of show drivers license on purchase and fuel grain is APCP which is more temperature stable, price per unit is higher but quality is there. The casings are reload able. I think either of those brands with APCP fuel grains would reduce CATOs. Certain G loads don't require certification.

Taketa airbags had Issues in high humidity and wasn't lab tested for high humidity kinda off topic but maybe Estes never tested for Canada's cold climate??? And you may have more failures than general users elsewhere?
 
The only thing I'll mention about reloadable RMS hardware is the Superlube coated o-ring assemblies for aft and forward closures itself is temperature sensitive. In a out of state student launch my team camped with assembled motors in our coats and sleeping bags for an multistage HPR launch without igniters inserted. The RSO recommended to keep the aft closure lose overnight then tighten it next morning because there was a bunch of moisture and the temperatures were below freezing and we really didn't have a warm place to store motors. He referenced the space shuttle and got a few wide eyed looks from the weary bunch. Virginia in October isn't Canada Cold however there was a bunch of moisture and fog with frozen dew. Didn't have an Aerotech CATO that day. One CTI Cato from other technical issues (blame us) not CTI. Then the booster CTI motor worked fine. Keep that motor kinda warm before launch it will be fine.
 
Independent of the temperature-cycling issues (which are important, but it's been covered well by others), I personally will not touch the E9 or E12 motors. I have just heard too many negative reports. I know there are some here who claim to have launched a zillion of one or the other without any failures, but I've heard enough anecdotal evidence that I am unwilling to trust any of my rockets to them. On the other hand, the 29mm E15 and F15 motors have been fine, as far as I can tell. Personally I am two for two with them. ;)

Sorry for your CATO but I would suspect it is something that you can get under control, both by motor selection and more careful management of motor storage. Good luck, I look forward to seeing those videos. :)
 
I've heard from fellow rocketeers in person that the only way to launch in extreme cold is to keep the engines warm and dry until right before use. Sounds like the consensus and you've had success with one so far. The only wildcard here is how were they stored in the hobby shop before you bought them? Not much can be done about that aspect I suppose.
 
Yes, very cold weather is not good for any solid propellant model rocket motor, no matter who makes it.

Some are more susceptible to catos in cold than others. For example i have had D12's blow in cold weather when C6's and A3's were fine. Indeed at one launch during the morning, a D12 blew at about 38-40 degrees. Later t got a bit warmer, about 45 degrees, another cato. MUCH later in the day, temperature mid-50's or 60, the third motor from the same pack of D12's worked FINE! Not exactly an ideal R&D project with such limited sample numbers, but it certainly was interesting for two to cato when cold and the one that did not was warmer.

After that is when I started to try to keep the engines warm inside a car with the heater on, not left outside in the cold. And once prepped, to fly soon while still "Warm". The rocket's motor too. :)

Another example was in the late 1970's. A rare snow in Birmingham, I converted a rocket car into a rocket sled, putting skis where the wheels were. I used some FSI D4 motors, I'd flown several packs before and all had been fine. Boom-boom-boom-boom, four of them blew at ignition. I used a C6, it worked fine, but the skids did not get any "traction" so the rocket car skidded to one side rather than run straight. Later used more of those D4's in warmer weather, and they were all fine. And indeed at least two of those packs that worked fine later, had been among the packs I'd had out in the cold previously. Only time I ever had any D4's to fail, was on that one COLD day, where 4 out of 4 blew.
 
Do you have the lot numbers for the failed motors. My current list is as follows:

C11
A 11 08 10
A 06 28 11

E9
09-04-12
06-28-11
06-14-01 A
A 06 28 11 1
A 01 12 16
A 09 15 14
A 1-12-16

E12
A 08-18-11
A 08 18 11 (E12-0)
A 11 15 11 (E12-0 & others?)
A 04 02 12 (E12-8 & others?)
05-15-12
 
Another data point to consider is the likelihood of a large spread in the temperatures the motor has been exposed to.
If the motor has been exposed to temps of, say, 140 degrees F, you shouldn't fire it if the current temperature is under 60 degrees F. 60 or above would be fine.

Or the time since said large spread. I had a group of D motors made 40 years ago that have definitely been exposed to temps 150 degrees or more in summer, and 20 degrees or less in winter, over many years, yet have been stored inside for 20+ years since then. All have worked flawlessly.
 
No. They do not crack from cold. They just shrink. The cardboard casing will not shrink as much as the proipellant and so there can be a gap between the outer propellant surface and the inner casing surface. This would be "bad".

Proven scientifically.

Keep your BP motors stable and launch no more than 75 degrees colder than the hottest temp they ever soaked at.


Cold temperatures cause BP to shrink and crack. Estes motors should always be stored indoors and relatively dry. Temperature cycling multiple times is even worse. Absorbing moisture over time adds to the problem. The E12's have a larger amount of BP which makes the thermal issues worse... stress from cold increases with length and diameter.

When I lived in the Northeast US, I would keep the BP motors in my pocket until the last minute when launching in the Winter.

Composite propellant with its rubbery binder is not as susceptible to cold/shrinkage issues. Some formulas can absorb moisture (certain effects chemicals) and swell over time.
 
aerostadt the lot number for the E12s that failed is A 05 15 12

sheesh why do I live in this county. I was going to try and do some more rocketry today but the temperature is -38c (-36f) our numbers are almost meeting finally. That is to cold to be out side for longer then like 5 minutes.
 
Maybe a policy of "if it's cold enough to freeze the cameras, not a good launch day" would make sense?

I admire your persistence and ability to push forward with the hobby in what I would consider extreme conditions. I bail when it gets below 50F/10C and switch to "build mode."
 
aerostadt the lot number for the E12s that failed is A 05 15 12

sheesh why do I live in this county. I was going to try and do some more rocketry today but the temperature is -38c (-36f) our numbers are almost meeting finally. That is to cold to be out side for longer then like 5 minutes.

I will add this lot number and mark it as cold weather. I went back to post #15 and was able to attach a summary of my old science project. I donot have the original full copy. I wonder if Estes Industries might have it from a long time ago. At the time I proposed that it was cracking of the BP propellant. There is a strong belief that it is the cardboard case separation. In any case cold temperatures are involved. I think that back in 1965 I might have cooled one motor to +10 DEg.F. and it did not fail. Probably, others might have done this kind of science project since 1965, but I have not seen the results. (Actually, such a project might be harder to do now, because I used a nice commercial recording thrust stand from RDC, which has long since gone out of business.) Large BP motors have a long history of bad failures. Willy Ley in his book, "Rockets, Satellites, and Space Travel", talks about Max Valier's rocket car Opel Rak II through IV back in Germany in the 1930's. Eventually, Max was killed in an accident trying to build such a car. Willy Ley in his book proposes the idea that tiny cracks are developing in the BP.
 
Marc_G - After the frustration of having my cameras freeze up losing footage I thought I was getting and having motors fail I am 100% on board. I think my new rules is if its colder to -15C launches are cancelled. That may seem to cold to all of you south of the boarder but seeing as though 6 months of the year is that cold and colder I cant do nothing for that long.

Aerostadt - interesting, Ill take a look. I guess I should become the cold weather rocketry guinea pig.
 
Mildly insulated launch box built of something fire resistant? That way you don't have to stuff-n-chuff in a big hurry with cold hands on the ice.

Just an idle thought.
 
I ran the second of several environmental abuse studies for an NAR R&D project with Estes' support. I fired 432 D12-5 motors.

Controls, temperature cycled, abused in lapidary tumbler (for a LONG time), dropped on floor from table, humidity cycled and humidity soaked. I also has x-rays of the motors and peeled several to verify what was happening.

The only crack was along the outside nozzle propellant interface. This results in LOWER peak thrust since the 'dome' never gets to full size. IF there is a propellant to casing dis-bond (and it is a mechanical 'bond' not an adhesive 'bond'), then the flame can get to the sidewall and propagate up the side leading to failure BEFORE the normal peak thrust time. This had been a mystery as everyone though the failures were occurring before the flame reached the casing, but the flame got to the casing sooner with the small crack. Again, that is a crack between dissimilar materials and results in LOWER pressure/thrust, but if the flame can then get up the sidewall because of a per-exisiting dis-bond, it will fail sooner.

I will add this lot number and mark it as cold weather. I went back to post #15 and was able to attach a summary of my old science project. I donot have the original full copy. I wonder if Estes Industries might have it from a long time ago. At the time I proposed that it was cracking of the BP propellant. There is a strong belief that it is the cardboard case separation. In any case cold temperatures are involved. I think that back in 1965 I might have cooled one motor to +10 DEg.F. and it did not fail. Probably, others might have done this kind of science project since 1965, but I have not seen the results. (Actually, such a project might be harder to do now, because I used a nice commercial recording thrust stand from RDC, which has long since gone out of business.) Large BP motors have a long history of bad failures. Willy Ley in his book, "Rockets, Satellites, and Space Travel", talks about Max Valier's rocket car Opel Rak II through IV back in Germany in the 1930's. Eventually, Max was killed in an accident trying to build such a car. Willy Ley in his book proposes the idea that tiny cracks are developing in the BP.
 
No. They do not crack from cold. They just shrink. The cardboard casing will not shrink as much as the proipellant and so there can be a gap between the outer propellant surface and the inner casing surface. This would be "bad".

Proven scientifically.

Keep your BP motors stable and launch no more than 75 degrees colder than the hottest temp they ever soaked at.

Cracking depends on the formulation of the BP, the range of temperatures, and the size of the charge. Temperature cycling of pressed propellants has been studied "scientifically" by other people who have "proven" there are internal cracks. See Journal of Pyrotechnics, etc.

If the BP absorbs moisture during temperature cycling, each time it's exposed to cold temperature it begins to crack. If the BP dries out, it further opens the micro cracks. Expose to moisture then freeze again, the cracks grow further. You will not see this on a typical xray image without sophisticated modern equipment. The additives Estes uses helps to reduce this effect, but the processing may have changed over the years, or it can vary from day to day.

Certainly, the delaminating of the casing is a major problem at cold temperatures. This can also happen with APCP, but less likely.
 
To be clear:

There were no propellant grain cracks in the D12-5 motors and I tested 432 of them. Others also tested hundreds of them. YES, propellant grains can crack but the studies you cited in Pyrotechnics Journals were not specifically for Estes commercially made motors. Just because a pyotechnician can studied mechanisms for grain cracking does not mean the Estes motors have grain cracks. As noted, size and formulation and method of manufacture/pressing will influence this behavior. just do not smash with a hammer....

The D12-5 motors were tested on the MIT static test stand with thrust time curves generated for each motor fired. It there were ANY cracks there would be evidence on the curves.

Now, the Estes C5 motors from year "X" had cracking in the grain. It was from the tool used to form the core when the motor was pressed ("pintle"?). That was bad.

Also, the casing did not "delaminate". The cardboard casing simply swells when the propellant grain swells at higher temps and then when the grain shrinks at lower temps, the cardboard does not shrink back at the same rate or all the way, resulting in a compromised mechanical 'bond'. This allows the flame to propagate up the outside of the propellant grain (inside the casing) generating way too much pressure.

FSI F100 motors also were prone to cracking. They also had a huge centerbore. F100 (F80) + cracks = :y:

Cracking depends on the formulation of the BP, the range of temperatures, and the size of the charge. Temperature cycling of pressed propellants has been studied "scientifically" by other people who have "proven" there are internal cracks. See Journal of Pyrotechnics, etc.

If the BP absorbs moisture during temperature cycling, each time it's exposed to cold temperature it begins to crack. If the BP dries out, it further opens the micro cracks. Expose to moisture then freeze again, the cracks grow further. You will not see this on a typical xray image without sophisticated modern equipment. The additives Estes uses helps to reduce this effect, but the processing may have changed over the years, or it can vary from day to day.

Certainly, the delaminating of the casing is a major problem at cold temperatures. This can also happen with APCP, but less likely.
 
apparently the video no longer works. sheesh I'm screwing up all my vids right now.
 
Reading thru this, our Canadian member recommended not launching below 5 degrees F (-15C)

The problem seems to be with big C, D or greater?

I was hoping to launch from frozen lakes and temperature down to zero Fahrenheit. I only launch standard B & C motors. Is 5 degrees fairly safe?

Will an Estes cheap ignition system light a rocket motor at that outside temperature? Do I need bigger batteries? I could use hand warmer packs.

Someone mentioned that 50 degrees F is cold??!? That doesn't even make sense. I think I've seen those temperatures in June and August before...
 
I stumbled upon the Quest Q-Jet motors...
"They are not susceptible to thermal cycling like black powder motors."
So it sounds like temperature isn't an issue?

I've only launched Estes motors before.
 
I didn’t know that about the Qjets... they’re very nice motors, although the Estes motors are better if you prefer a slightly longer burn.
 
I'll be interested to see what Gary (or whoever is answering questions in the big Aerotech thread) says about minimum temps for Q-Jets. Since they are Black Max composite, rather than black powder, I expect what causes issues is different than with Estes BP motors.

Ignition at lower temperatures would only be an issue in that batteries perform poorly when cold (and that is true of alkaline, lead-acid and lithium-polymer chemistries). I'd certainly want to keep the launch controller battery warm and/or increase the nominal voltage if flying out in sub-freezing temperatures. Q-Jet igniters don't need a whole bunch of current, so they would be relatively forgiving under really cold conditions.
 
Reading thru this, our Canadian member recommended not launching below 5 degrees F (-15C)

The problem seems to be with big C, D or greater?

larger propellant mass relative to the casing. So mini-A motors, 18mm C motors, and nearly all the larger BP motors (not sure about C11) are susceptible.

it seems the real culprit is difference of min and max temp exposures. Someone has mentioned a spread of 75 degrees F is the limit, but I don't know if that has been properly experimentally determined.

I was hoping to launch from frozen lakes and temperature down to zero Fahrenheit. I only launch standard B & C motors. Is 5 degrees fairly safe?
Air temp at launch is not the factor as much as the temp of the motor itself. If you can keep the motor warm(ish) until you use it and don't let it sit on the pad too long, you should be fine.
Will an Estes cheap ignition system light a rocket motor at that outside temperature? Do I need bigger batteries? I could use hand warmer packs.
batteries need to be kept warm to push the electrons along. Handwarmer should suffice.

Someone mentioned that 50 degrees F is cold??!? That doesn't even make sense. I think I've seen those temperatures in June and August before...

If you're like me (from GA) 50 degrees F is colder than I want to be. :)
 
Back
Top