What did you do rocket wise today?

madcow rocketry
Advertise with us
The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Sent a couple of emails to TRA and Aerotech to see if there is any actual measured temp data available for the external case temps as recorded during motor certification.

I've reviewed several recent motor certification test data sheets on the Tripoli website and I can only see a "pass" statement with regard to the NFPA 1125 section 7.4.1 external case temp requirements. As the "shall not exceed" requirements are either 200, 220 or 316 degrees C, n

"Common sense" says there should not be a problem here because many, many level 3 F/Glass motor mount tubes and MD airframes have been flown over the years with big, hot motors. So, we'd have heard all about it and if there was a problem then kits would have been redesigned if the case temps were cooking the epoxy resins out of the F/Glass matrix. Wouldn't we?

The reason I'd like to know more actual data is that I'm preparing a build plan to roll a composite material motor mount tube for an M class motor, using a commercially available Bio-Epoxy rather than the more traditional products like West Systems. To help me assess its safe use in this particular component, I'd like to understand the typical operating temperatures that the Bio-Epoxy composite MMT would need to be capable of sustaining, all while retaining its structural integrity.

Anyone got an insight into this topic?
 
lr64 said:
BTW, when I win Powerball, I will purchase a large property, not too far out of town. It will have a rocket launching area, a dirigible hangar for indoor free flight and MMX rockets. There will be a pond for RC sailing guys, There will be a weather resistant, solar charged RC sailplane winch always available. Also a solar charged golf cart for retrieval purposes for anyone with limited mobility. The dirigible hangar will be oriented perpendicular to the prevailing winds for slope soaring. Maybe I'll build my subterranean mad scientist's lair underneath. In that case, fire and blast resistant areas with good ventilation and at least two exits will be provided for those who want to make propellant, as well as appropriate magazines for such material.
Click to expand...
Sounds great. Please tell me there will also be fully equipped shops, separated into separate rooms with separate HVAC systems, for dirty work (wood shop, machine shop, etc.) and clean work (electronics, kit assembly, etc.). Also with a half bath and a kitchenette.
 
BrendanH69 said:
The reason I'd like to know more actual data is that I'm preparing a build plan to roll a composite material motor mount tube for an M class motor, using a commercially available Bio-Epoxy rather than the more traditional products like West Systems. To help me assess its safe use in this particular component, I'd like to understand the typical operating temperatures that the Bio-Epoxy composite MMT would need to be capable of sustaining, all while retaining its structural integrity.

Anyone got an insight into this topic?
Click to expand...
prfesser said:
I would check the specs of the Bio-Epoxy against West's; softening temperature, maximum-use temperature, etc. If the Bio-Epoxy's temperature ratings aren't materially different from those of West or other commonly used epoxies, it ought to be okay.
Click to expand...
That, and this: try going by the maximum allowed temperature under 1125, 7.4.1; if the epoxy can stand that, then you don't need to know anything else. That's what requirements and specs are for.
 
prfesser said:
I would check the specs of the Bio-Epoxy against West's; softening temperature, maximum-use temperature, etc. If the Bio-Epoxy's temperature ratings aren't materially different from those of West or other commonly used epoxies, it ought to be okay.
Click to expand...
West isn't particularly good with heat. Even PVC pipe is better. There's a reason so many homebuilt composite airplanes are white. If I was going to the trouble of making a motor case, I'd want something good for a higher temperature.

from reliable and unreliable sources on the net:
West heat deflection temperature 48- 53C
PVC heat deflection temperature 54-80C
ProSet HDT room temp. cure 55 C
" " post cure up to 88 C
System 3000, after post cure 154 C, but that post cure has several temperatures, ending up at 149 C!
You can find systems that will go higher.

I try not to leave anything made with epoxy like West in a closed car on a sunny day. But something like West is probably fine for body tubes, etc. if you take that precaution an don't live in a really hot place.



jqavins said:
Sounds great. Please tell me there will also be fully equipped shops, separated into separate rooms with separate HVAC systems, for dirty work (wood shop, machine shop, etc.) and clean work (electronics, kit assembly, etc.). Also with a half bath and a kitchenette.
Click to expand...
Of course! That should go without saying.
 
Finished up a couple of rockets. The Estes Impulse is from the original Pro Series and a clone kit is available from Bad Boy Rocketry. It's a cluster with 2x24mm motors. I'll fly it on the 18th, weather allowing. The 2nd is the Estes Fox Fire. I love the looks of this one but retention is strictly friction fit.
 

Attachments

  • Estes Fox Fire.jpg
    Estes Fox Fire.jpg
    119.6 KB · Views: 0
  • Estes Impulse.jpg
    Estes Impulse.jpg
    253.9 KB · Views: 0
RokitFlyr said:
In 20 or so years, I've never had a problem with West Systems and heat in a vehicle or sun. Temps here in central Wa. are often in the 100 degree range.
Click to expand...
I once helped someone straighten out an epoxy/glass wing by strapping it to a door and leaving it in a car on a sunny day. It worked. I've also had a foam wing that was merely inside of a translucent bag have a melt down*. Not sure how much of that was the foam, and how much the epoxy.

*Maybe "sag down" would be more accurate.
 
jqavins said:
That, and this: try going by the maximum allowed temperature under 1125, 7.4.1; if the epoxy can stand that, then you don't need to know anything else. That's what requirements and specs are for.
Click to expand...
I looked that up. 200° C for motors under 160 n-s, 220 for above. Except for single use motors above 80 n-s, when it's 316. In other words, much higher than most epoxies are rated for.
 
Almost finished designing my future EggFinder "Base Station".

(Click images to enlarge)
1.png 2.png

Base station features:
2x EggFinder LCD Rx boards: One for GPS tracking, the other for rocket telemetry
1x EggFinder LCD-GPS module (For GPS board)
1x LCD Module (For GPS board)
1x EggTimer Voice Module
1x EggFinder BT module (for cell phone connectivity)
1x AdaFruit 2.5W mono amp.
1x Pololu 5V step-down regulator (For powering amp & voice module)
1x Self-enclosed mini speaker
1x 10K audio-taper Pot for volume control
1x SPDT switch with BBM switching (For sending GPS or Telemetry to Voice Module)
1x 2S 1500mA LiPo pack
1x LiPo charging port with separate Run/Charge switch
1x On/Off LED laminated power switch
And last but not least, an adjustable cell phone cradle
 
Last edited:
lr64 said:
I looked that up. 200° C for motors under 160 n-s, 220 for above. Except for single use motors above 80 n-s, when it's 316. In other words, much higher than most epoxies are rated for.
Click to expand...
I would assume, since the regulation is written specifically for these rocket motors, that the numbers are based on what is realistically achievable. It would surprise me if the actuals are much lower. There will be some margin built in, so I expect the actuals are in the ballpark of 10 to 20 degrees lower.

On the other hand, since we know that we don't get 2nd degree burns from removing cases after a flight, it's clear that those are peak temperatures, and the cases cool off quickly after the burn is complete. So the duration, or better yet the whole time-temperature curve, is important. And getting that from the test data is probably pretty difficult, and in reality it depends on the MMT's thermal properties as well as the motor's.

@BrendanH69, your best bet is probably to make a tube, stick the motor you plan to use in it, and ground test. If you're able, it'd be cool to place a thermocouple or two in the tube and get that time-temp curve.
 
jqavins said:
I would assume, since the regulation is written specifically for these rocket motors, that the numbers are based on what is realistically achievable. It would surprise me if the actuals are much lower. There will be some margin built in, so I expect the actuals are in the ballpark of 10 to 20 degrees lower.

On the other hand, since we know that we don't get 2nd degree burns from removing cases after a flight, it's clear that those are peak temperatures, and the cases cool off quickly after the burn is complete. So the duration, or better yet the whole time-temperature curve, is important. And getting that from the test data is probably pretty difficult, and in reality it depends on the MMT's thermal properties as well as the motor's.

@BrendanH69, your best bet is probably to make a tube, stick the motor you plan to use in it, and ground test. If you're able, it'd be cool to place a thermocouple or two in the tube and get that time-temp curve.
Click to expand...
If I can't get real data, then maybe a home made test method could be possible. Motors are scare and super expensive here, so would be idea if it could be done on a flight. Let me think about that.

I'm thinking the same way as you - we all have experience that our cases (incl. DMS motors) are hot to handle when we recover them, but my impression is that they're never as "baking oven hot" as as the the NFPA 1125 limits. That being said, the peak case surface temps are going to be around motor burnout, which is usually significantly earlier than when we walk up to the rocket and recover it.

For the moment, I'm curious that the real data MUST be out there, because it is required to be measured and recorded during certification otherwise there'd be nothing to back up the "pass" declaration if the Fire Authorities were to ask for the evidence.

The temperature limits stated in NFPA 1125 7.4 of 200oC (392oF), 220oF (428oC) and 315oC (599oF) are pretty big figures and probably easy to achieve in the certification process. However, being 10 or 20 degrees under them as you surmise would still be very challenging for the epoxy within a composite structure of a MMT or MD airframe. So, how do we know which epoxies would be acceptable for the specific application when scratch building MMTs, especially for HPR and long burn HPR motors? What epoxy do Aerotech use in their DMS FWFG cases, because clearly it must be good stuff to survive both the surface temp requirement AND the structural, pressure and failure mode requirements that are also required.
 
Investigated whether it's worth trying to design black powder motor cluster/parallel staged configurations for windy-day egglofting:
  • 2X A10-3 cluster B eggloft (vs. B6-4 off a piston or B14-3T)
  • 2X A10-0 + B4-4 cluster staged C eggloft
  • 2X B6-2 cluster C dual eggloft
  • 2X A10-P + B4-2 cluster C dual eggloft
  • 2X B6-0 + C6-5 parallel staged D eggloft
  • 2X B6-0 + C6-5 cluster staged D eggloft
  • 2X C5-3 cluster D dual eggloft
  • 2X C11-0 + D12-5 parallel staged E dual eggloft
  • 2X C11-0 + D12-5 cluster staged E dual eggloft
  • 2X D12-0 + E16-8 parallel staged F dual eggloft
  • 2X D12-0 + E16-8 cluster staged F dual eggloft
Finding: doubt any of the cases pencil out as beating a single composite motor or a BP motor off a piston.
 
BrendanH69 said:
If I can't get real data, then maybe a home made test method could be possible. Motors are scare and super expensive here, so would be idea if it could be done on a flight. Let me think about that.

I'm thinking the same way as you - we all have experience that our cases (incl. DMS motors) are hot to handle when we recover them, but my impression is that they're never as "baking oven hot" as as the the NFPA 1125 limits. That being said, the peak case surface temps are going to be around motor burnout, which is usually significantly earlier than when we walk up to the rocket and recover it.

For the moment, I'm curious that the real data MUST be out there, because it is required to be measured and recorded during certification otherwise there'd be nothing to back up the "pass" declaration if the Fire Authorities were to ask for the evidence.

The temperature limits stated in NFPA 1125 7.4 of 200oC (392oF), 220oF (428oC) and 315oC (599oF) are pretty big figures and probably easy to achieve in the certification process. However, being 10 or 20 degrees under them as you surmise would still be very challenging for the epoxy within a composite structure of a MMT or MD airframe. So, how do we know which epoxies would be acceptable for the specific application when scratch building MMTs, especially for HPR and long burn HPR motors? What epoxy do Aerotech use in their DMS FWFG cases, because clearly it must be good stuff to survive both the surface temp requirement AND the structural, pressure and failure mode requirements that are also required.
Click to expand...
They won't tell you how LONG the casing is hot, but some temperature indicating stickers might be a good start. You can probably find them cheaper than at McMaster-Carr, but if you're in a hurry, they ship pretty quickly.
https://www.mcmaster.com/products/temperature-stickers/
That would be simpler than using a thermocouple, amplifier, etc. and some kind of data recording, though I bet some flight computer or other could handle it.
One commonly available epoxy that has a high temperature rating is the original JB Weld. https://www.jbweld.com/product/j-b-weld-professional-size However, I've heard that it's metal filled, which probably means it's heavy, and unsuitable for wetting out composite fabrics. But maybe a could of rings of it could be in contact with the casing, with some kind of insulation everywhere else. I guess muffler cement is brittle, and then there are refractory cement and hydraulic cement, but I suspect they're a bit on the brittle side. Things can be done with waterglass and other substances or fabrics, but that might be brittle, too. Certainly the waterglass and ceramic fiber composite sample I attempted was brittle, but maybe I brought it up to temperature too fast. If you don't slowly heat it first, waterglass can foam up when heated quickly, though I understand that after slow heating it isn't vulnerable anymore. Also known as sodium silicate. Can be found in some concrete sealers, at pottery supply stores, etc.
 
Came home from work to a package from Wildman.... A 98mm Aeropack retainer, a Skyangle Cert 3XL, and a couple of other goodies.... Now to start building that massive LOC 7.5" behemoth that i staking up floor space in its box in my garage.... As soon as I clean off my workbench, that is!

I also got the first coat of pain on my MDRM.
 
lr64 said:
They won't tell you how LONG the casing is hot, but some temperature indicating stickers might be a good start. You can probably find them cheaper than at McMaster-Carr, but if you're in a hurry, they ship pretty quickly.
https://www.mcmaster.com/products/temperature-stickers/
Click to expand...
Thanks for the link to the McMaster temp stickers, they're a great and simple idea to try first on a regular HPR flight. Will look into ordering some.

You are also correct - JB Weld is totally unsuited to wetting out composite cloth materials for rolling tubes. I do of course use it for anything the attaches directly onto the MMT, such as fin tabs, Centering Rings etc.
 
lr64 said:
They won't tell you how LONG the casing is hot, but some temperature indicating stickers might be a good start. You can probably find them cheaper than at McMaster-Carr, but if you're in a hurry, they ship pretty quickly.
https://www.mcmaster.com/products/temperature-stickers/
That would be simpler than using a thermocouple, amplifier, etc. and some kind of data recording, though I bet some flight computer or other could handle it.
One commonly available epoxy that has a high temperature rating is the original JB Weld. https://www.jbweld.com/product/j-b-weld-professional-size However, I've heard that it's metal filled, which probably means it's heavy, and unsuitable for wetting out composite fabrics. But maybe a could of rings of it could be in contact with the casing, with some kind of insulation everywhere else. I guess muffler cement is brittle, and then there are refractory cement and hydraulic cement, but I suspect they're a bit on the brittle side. Things can be done with waterglass and other substances or fabrics, but that might be brittle, too. Certainly the waterglass and ceramic fiber composite sample I attempted was brittle, but maybe I brought it up to temperature too fast. If you don't slowly heat it first, waterglass can foam up when heated quickly, though I understand that after slow heating it isn't vulnerable anymore. Also known as sodium silicate. Can be found in some concrete sealers, at pottery supply stores, etc.
Click to expand...
Brendan is trying to build with bio materials, including a specific bio epoxy, so JB is out of the question. Also, it's pretty thick stuff that I doubt would wet out fabric at all without being massaged in.

Substituting refractory cement for JB Weld to save weight? I don't think you thought that through; you're too smart to seriously suggest that.

Waterglass is neat stuff, though I only know that in principal. (A water soluble silicate? That's just bizarre and cool.) I've been meaning to try some stuff with it. I don't see how it could possibly not be brittle.

In any case, JB, waterglass, cements, fiberglass batts, and so forth are all off the approved materials list, so all of this is moot.

@BrendanH69, have I gathered correctly that you plan to use Aerotech SU motors? Those have thrust rings, so you don't need an engine block at the forward end of the MMT. In point of fact, you could leave out the MMT completely, and that would make this epoxy temperature problem go away. A tube for the motor is a great convenience, but you really don't need it. Make your wooden CRs with their ID to go with the case diameter so they hold the motor directly. It makes lining up the motor to load it a bit of a pain, and installing the CRs a challenge, and those are really the only problems. (Tack each ring to an motor case with a single drop of CA. The case is a carrier to glue the rings to the inside of the BT. Once the glue is fully cured, give the motor a twist; CA sucks in sheer, so the case will come right out.)
 
Very carefully laid out and drilled six holes in the 260 Space Booster. Looked at the result and reconsidered strength issues, so epoxy will be used instead. In this rocket it means that the shock cord won't be replaceable at the lower end, but I don't expect to fly it often enough to worry about it. 1" tubular nylon in a 4" rocket ought to hold up for a good while, anyway.:)
 
Kind of a late update. Flew with the club this past weekend. The launch was out at the Seed Farm so I took the opportunity to fly some of my larger models.

In the order that appear.

- Vaughn Bros. Blobbo. Flew on a D12-5. Nice flight. Easy to track and recovered safely.
- Falcon Commander 2.0" upscale. Flew on an E30-4. Another perfect flight with good safe recovery.
- Maxi Alpha III. Flew on a D22-4. My rebuild added a little bit of weight so it's just a touch heavy for a D12. The D22-4 is a good replacement.
- Upscale 3.1" Yankee. Flew nicely on the F67-6. Only flew to about 500 ft. so there is a lot of room for larger motors. Nice safe recovery.
- Upscale 2.5" Upscale Laser. Flew really well on the E30-4.
- Maxi Streak. Flew on the C6-5. Nice high flight. Easy to track and recovered closely.
- Butt Ugly. This we the 97th flight of this scratch build. Flew on a D12-7. Nice high flight. Easy to track and landed close to the pad.
- Luna Bug BT80 Upscale. First flight since the updates to Steam punk. Due to the additional weight, i attempted to fly on an E20-4. Unfortunately the rocket was unstable and tumbled. It hit the ground nose first but no damage done.

05052024Launch_1.jpg05052024Launch_4.jpg05052024Launch_5.jpg05052024Launch_6.jpg05052024Launch_8.jpg05052024Launch_9.jpg05052024Launch_11.jpg05052024Launch_13.jpg
 
lakeroadster said:
Do a swing test on that awesome Luna Bug @Back_at_it . Then add some nose weight and do another swing test to verify stability.
Click to expand...

It passes the swing test with flying colors. The interesting thing is that the CG has only moved a 1/4" toward the rear with all of the updates. The rocket flew perfectly the week before without any issues.

At this point, a couple of oz of nose weight isn't going to hurt anything.
 

Similar threads

NTP2
What do you do (or did) for a living?
7 8 9
Replies
252
Views
9K
conneryc
conneryc
MarsLander
Bad Boy Rocketry Rocks. Just sayin'
Replies
4
Views
299
ep29030
ep29030
kramer714
Student Rocket Programs - PDR Tutorial
Replies
0
Views
135
kramer714
kramer714
KenECoyote
Is it really a model rocket if you don't launch it?
4 5 6
Replies
158
Views
6K
bjphoenix
B
T
First-time UK Rocketeer looking for help!
Replies
6
Views
571
jqavins
jqavins

Latest posts

Back
Top