reloading question

[Schuyler]

I just got my first reload casing in the mail and I noticed that it says "Only reload immediatly before use". My two questions are: 1) What is the reason for this? and 2) How far in advance can I load it?

 

[hardinlw]

Depends on the casing.

For the hobby engines and older style delay elements on the high power, the concern is that pressure is applied to the delay element which may cause it to compress with time resulting in failure of the O-ring to seal. If the seal fails, you get blow-by which may damage the case or cause premature ejection. A secondary concern is that the propellant will oxidize and/or absorb moisture once removed from the sealed package. If you seal up the assembled engine in an air-tight container (zip-lock bag works) then that concern is alleviated. For the hobby engines, I commonly build them up ahead of time (a day or two is fine) and thread on the aft closure without tightening it. I also leave off the ejection charge and igniter. I seal up the engines, igniters, and ejection charges in a zip-lock bag. At the field, I tighten the closures, install the ejection charge, and install the igniter.

Another caution that is not obvious is to avoid getting grease on the ends of the delay element. That can make it ignite late or not at all which will ruin your day. I'm working with a TARC team and taught them to have one person greasing the O-rings and casings and another assembling the delay elements, etc., so there is minimal chance of getting grease where it does not belong. That is also easier done at home than at the field. I already had 2 of the 24mm cases and bought a third so they could make up 3 engines the night before test flying. When we were flying in 30 degree weather, that was really important. Frozen fingers don't work too well assembling engines at the field.

 

[blackjack2564]

I usually load up several motors the night before a launch. Much easier to do sitting at the table at home, than a windy,busy, launch site. I have flown motors that were loaded a year and a half before hand, with no ill effects.

The motor paperwork that comes with the reload must be consumer friendly for warranty purposes.
If you think about it, what's the difference between a reloaded motor and a single use which can sit for years before use.

 

[Handeman]

Larry and Jim pretty much covered everything. The only other issue you might come across is that some of the propellants were not very compatible with the delay grains. Prolonged exposure of the grain to the delay could cause problems with the delays. By prolonged, I mean many months and or years in the package. Some of the Aerotech reloads now come with the delay or grains sealed in individual plastic bags. So if you make up one of these and let it sit for 6 months or more, you might have an issue with delay.

If you are leaving assembled motors sit for over 6 months, you have too many cases and need to send some to me so I can verify they still work. 20 or 30 test flight aught to be a sufficient test.

 

[jj94]

Above three answers nailed it. What I do if I happen to load a motor before immediate use is loosen both closures by one turn, leave out the ejection charge, and leave out the igniter. Loosening the closures just makes sure that the o-rings don't compress. Leaving out the ejection charge makes sure that black powder grains won't get in between the o-rings and what ever they are in contact with. That makes sure that the black powder won't screw up the seal that the o-rings make after the closures are tightened. Leaving out the igniter is self explanatory. It makes sure that the igniter won't become damaged during handling and to prevent a fire hazard. What I also do is to put a sliver of Blue Thunder propellant snugly in the C-slot of hobby line reloads. It's easy to ignite, burns very hot, and it doesn't oxidize much. It aids in fast and complete motor ignition. If the propellant from the reload happens to oxidize during storage, the Blue Thunder should be able to ignite it anyway.

 

[Crazyrocket]

To add to the above, I also put a piece of tape on the motor case to put a note to remind myself to tighten the closures and add BP. Nothing stinks more than remembering to add BP AFTER the launch button is pressed!

 

[Schuyler]

Thanks for all the replies everyone! And Handeman, sure, I'll get those cases in the mail right away

 

[Graham Orr]

Argh...

Well, we were going to have another launch this week for the experimental engineering class. We had a launch last week and got 23 flights off (of 32 planned, though 2 rockets ate it)...

This week we had 30+ motors (RMS) prepared, mostly H's and I's but the launch has been cancelled due to W (25 mph sustained winds). The next time the class has the opportunity to fire the motors is next year. So basically we have 30+ motors sitting here that we must do something with.

I don't think the school would be happy if we just burned off $800 of reloads for fun. Perhaps pull out the forward closure in all R T G motors and put them in an isolated bag and hold them until next year? (Chemical incompatibility in W motors isn't as much of an issue, I believe. Also, most of the rockets have electronic deploy.)

Ideas?

 

[blackjack2564]

Graham....
I have kept many loaded motors over a year with no problems. Especially if your flying electronics...no worries.
Just loosen the closures a few turns and if you have nozzle caps,use them.
No further storage requirements other than labeling them so next year you know what's, what.

If you don't have the caps, store them in baggies, Tupperware type containers, or something to keep out moisture and humidity.

There is really no need to remove the closure.

The only issue I'm aware of is with redlines. The interaction of delay and propellant can cause erratic delay times. If you have any of those I WOULD remove them if motor ejection is used. If they are being used in altimeter deploy, there should not be an issue.

To be 100% sure on every thing else, call or e-mail Gary at AT. He is really good about getting back to you on issues like this. And nothing beats the source to resolve an issue.
By the way, how you making out on getting those tubes for the 25 rockets.
PM me if I can be any help, I have lots of resources [for many other items] if Tom Henderson doesn't work out.
Your Mudd 4 rocket looks to be the spitting image of a Wildman 3. Ya know they come in carbon also, and be modified to your specs.

 

[Graham Orr]

So...
The prof is going to let us use the motors for our personal use at the next ROC launch...

 

[dave carver]

wheeeee

 

[WillMarchant]

12 hours according to the https://www.aerotech-rocketry.com/warranty.aspx warranty.

 

[Pantherjon]

Guess I am hosed if the 29mm case goes blooey from the load that is loaded in it..Been loaded in there so long I have forgotten WHAT load I have in there!..It's a hobby line case and I am pretty sure it is a G something- I think...It has been oh, 3 maybe 4 months now?

 

[blackjack2564]

Your absolutely correct John! That reload is DEFINITELY a danger and should be disposed of immediately and correctly.

I just happen to have the needed equipment to do the job safely.
Next launch give me the load as soon as I see you and I will dispose of it in my H.D.R. [ Hazemat Disposal Rocket.]:blush::blush::blush:

We will both appreciate the experience and you can sleep good at night full knowing it is no longer a danger to you or rocketry in general.:cyclops::cyclops:

 

[Pantherjon]

WHEW! You are such a savior Jim! Now I can sleep easily knowing this motor will be disposed of properly..Oh, BTW, I was rummaging around the motor boxes(actually putting them back in after the cat tipped them over!) I discovered that the motor in question is actually in the 24/40 case! I believe it is an E28-7T as that is the only 24mm 'card' in the box(the other one is for a 54/852 reload which this obviously is NOT)..

Am sure we can 'rig' an adaptor for the HDR to properly dispose of this highly danerous motor!

:roll:

 

[berlinetta]

This was all good information. I have a J350 which I assembled for LDRS and never got to fly it, I am looking to fly it this April though.