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Motor casing temperature

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lmt56

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I am working with a group on the SLI program and one thing they want to do is put some sensors on the motor tube to measure its temperature during flight.
To go alone with this I would like to find some stick on thermometer to place on the motor casing.
Does anyone know of a good source for these?
Also what kind of temperature should we expect?
The motor will be one of the following.
6 grain 54mm
6xl grain 54mm
2 grain 75 mm
3 grain 75 mm
I am thinking 400 to 500 degrees.
Thanks for any helpfull input.
 

dave carver

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I'm pretty sure 200 or so is as hot as they get. 500 would have things so hot that the tubing could burst into flames as paper combusts at 451 degrees. Plus I've used PVC as motor mount tubes, 500 would definatly have left things welded together.
 

blackjack2564

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200 C = 392 F is the norm high, so your close.

I had these stick on sensors used to check just like your trying to find, don't remember where they came from. They actually will show in color and digital read out what the high temp reached is. Only can be used once as they permanently show the result. Place one right where liner meets nozzle and another where liner meets forward closure to attain the highest temp. and most useful data. [in most cases]

By the way these were thin enough they did not interfere with fitting motor into MM tube, something you must be aware of when purchasing these.

You might try e-mailing AT I know they use them, and could probably give you the source for your experiment.
 
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Diosces

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Used something similar to these for a mechanical design project

Max T paper thermometers
Like blackjack said, get the ones single use ones that display maximum exposed temperature
 

lmt56

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200 C = 392 F is the norm high, so your close.

I had these stick on sensors used to check just like your trying to find, don't remember where they came from. They actually will show in color and digital read out what the high temp reached is. Only can be used once as they permanently show the result. Place one right where liner meets nozzle and another where liner meets forward closure to attain the highest temp. and most useful data. [in most cases]

By the way these were thin enough they did not interfere with fitting motor into MM tube, something you must be aware of when purchasing these.

You might try e-mailing AT I know they use them, and could probably give you the source for your experiment.
Hello Jim
These sound like just what I am looking for.
If you remember where you got them from please let me know.
Best
L. T.
 

blackjack2564

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They looked similar to these from the above link, but to be exact you will have to contact Gary or Karl at AT. The motor I was flying was a demo supplied by AT, and had them already attached.

4A_4B_LABELS_m.jpg
 
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rocketdude25

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I'm pretty sure 200 or so is as hot as they get. 500 would have things so hot that the tubing could burst into flames as paper combusts at 451 degrees. Plus I've used PVC as motor mount tubes, 500 would definatly have left things welded together.
Don't forget there is some thermal lag associated with the casing itself. Most HP motors burn in the 3 to 4 second range. I would guess the casing itself never gets much above 60 C (about 140F). Standard aluminum thermal conductivity is in the order of 221 W/mk. I think CTI uses 6061-T6 grade aluminum so it would depend on the thickness of the casing (which I do not know off hand). That being said, if anyone has measured a burn out temp of casing please post it here.
 

bobkrech

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The motor casing temperature should not exceed 200 C or 392 F as per NFPA 1125 certification requirements. At NAR S&T we have used both thermocouples and temperature indicating strips to measure compliance. Larger motors like the ones you mention are likely to be just below 400 F

The hottest part of the motor tube is usually, but not always at or near the nozzle.

Omega make a number of 4 and 8 temperature sensing strips.

My choice is shown below.

http://www.omega.com/ppt/pptsc.asp?ref=TL-8&Nav=temf02

[FONT=Verdana, Arial, Helvetica, sans-serif]TL-8-330-10 [/FONT][FONT=Verdana, Arial, Helvetica, sans-serif]
[/FONT][FONT=Verdana, Arial, Helvetica, sans-serif]$13.00 [/FONT][FONT=Verdana, Arial, Helvetica, sans-serif]Eight Temperature Range Label (330, 340, 350, 360, 370, 380, 390, 400°F), package of 10 [/FONT]


Bob Krech, NAR S&T
http://www.nar.org/SandT/docs/ST-MotorTestingManual.pdf
 

troj

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NFPA 1125 says that a motor's case cannot excess 200C (392F)

-Kevin
 

Jeroen_at_CTI

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I think CTI uses 6061-T6 grade aluminum so it would depend on the thickness of the casing (which I do not know off hand). That being said, if anyone has measured a burn out temp of casing please post it here.
IIRC this was answered via a PM some time ago.

All 54 motors and most 75 motors that we fired at the test stand can be handled with bare hands after firing. I'd say they are less than 60 to 70 degC. Some might get up to 80 degC or so, but not much more. For sure a lot less than the 200 degC requirement.

Jeroen
 

FredA

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As I recall, the 200C max case temp was just bumped to 220C.
 

bobkrech

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As I recall, the 200C max case temp was just bumped to 220C.
Not as far as I know, but IIRC it's up for discussion in the current round of NFPA 1125 modifications proposals.

Bob
 

billspad

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Not as far as I know, but IIRC it's up for discussion in the current round of NFPA 1125 modifications proposals.

Bob
I think that's one of the things that they all agreed on but it still doesn't take affect until 2011.
 
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