What did you do rocket wise today?

Onebadhawk
eggtimer rocketry
the model rocket show
The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
jqavins said:
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.)
Click to expand...
I must have missed it. I thought he was going to use a commercially available bio-epoxy, but that it hadn't been selected yet. I got the impression that different bio-epoxies had different thermal ratings.

The refractory cement wasn't to save weight, it was to resist high temperatures.

People do things with waterglass and various kinds of clay, etc. Maybe one of them isn't particularly brittle. And waterglass isn't some exotic material with fancy organic synthesis, solvents, etc. Nor is cement. I had not been suggesting fiberglass batts, though I did mention ceramic fibers. BTW, natural isn't the same as safe. When I was a kid, I had an asbestos rock that I could peel fibers off of. Fortunately, I didn't do much of that.

BTW, I ran across someone on the web who said they made paper tubes with waterglass as an adhesive. Perhaps they'd be more temperature resistant tubes than any of the more ordinary epoxies.
 
jqavins said:
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.

@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.)
Click to expand...
Yep, you got it.

I'm planning to roll my own composite motor mount tube to hold 75mm Aerotech single use (DMS) motors, at least one L and then an M1350W for a level 3 attempt. Aerotech RMS and CTI Pro75 reloadable motors are not completely out of the question, but only if I can borrow cases. The rocket design is not going to be minimum diameter, so I'll need the MMT as part of a fin can assembly to go into the approx. 163mm (6.4inch) OD airframe, which I'm also intending to roll myself with the same materials.

I like your suggestion on using CRs that hold the case without a MMT, but the big restriction for me is getting cases to utilise as the assembly/carrier tool. However, I'll put that idea into the mix when I get some TAPs on board (they're 1000-times more scarce than HPR motors in Oz!).

Having used about 1.5kg of the stuff already, I'd say the Bio-Epoxy is equally suited to wetting out fabrics as the West Systems epoxy I've used for the last few years. I've wetted out 300gsm F/Glass, braided carbon fibre, and now the 200gsm and 300gsm flax with it. It's only a tiny bit thicker when mixed and it applies in very much the same way by brush or mini-roller. It's is slower to go off than West, which can be handy, but if definitely takes two to three times longer to get to the "leather stage" and full cure.

However, because it's a new and unconventional epoxy, I'm interested in knowing more detail about the conditions its going to operate in (the case temperatures) and referencing this to the more conventional epoxies used for making MMTs.
 
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.
Click to expand...
Went to the McMaster-Carr site and selected two different packs of 10 temp stickers for about US$40. Went to check-out and shipping was US$57!!!!! :mad: They just need sticking in an envelope and popping into USPS international letter post! Even buying them from an Australian site would be cheaper!
 
lr64 said:
I must have missed it. I thought he was going to use a commercially available bio-epoxy, but that it hadn't been selected yet. I got the impression that different bio-epoxies had different thermal ratings.

The refractory cement wasn't to save weight, it was to resist high temperatures.

People do things with waterglass and various kinds of clay, etc. Maybe one of them isn't particularly brittle. And waterglass isn't some exotic material with fancy organic synthesis, solvents, etc. Nor is cement. I had not been suggesting fiberglass batts, though I did mention ceramic fibers. BTW, natural isn't the same as safe. When I was a kid, I had an asbestos rock that I could peel fibers off of. Fortunately, I didn't do much of that.

BTW, I ran across someone on the web who said they made paper tubes with waterglass as an adhesive. Perhaps they'd be more temperature resistant tubes than any of the more ordinary epoxies.
Click to expand...
Yeah, when you put it that way, I'm not altogether sure he's picked one, just that it has to be bio, which puts out JB and most of the other epoxies on the market. The notion of fiberglass batts was my own; if you want something for insulation, why not use insulation? But the answer is that it's not a bio material.

On the natural isn't the same as safe point, my favorite is deadly nightshade. Or, on the flip side:
Start with the seeds of a particular type of grass. Grind them up, removing the hulls, to a super fine powder. Add water to that, and introduce a microbial culture. Work the combination until two certain proteins emerge from the grain powder which combine into a structure that gives the mass both cohesion and springiness. Then allow the microbe to thrive, which causes the mass to swell, taking on a spongy structure. Finally, heat treat the spongy mass until the microbes die and the protein pair is altered to give the mass a semi fixed shape. And people call this "all natural" and "unprocessed".​
 
Last edited:
BrendanH69 said:
Yep, you got it.

I'm planning to roll my own composite motor mount tube to hold 75mm Aerotech single use (DMS) motors, at least one L and then an M1350W for a level 3 attempt. Aerotech RMS and CTI Pro75 reloadable motors are not completely out of the question, but only if I can borrow cases. The rocket design is not going to be minimum diameter, so I'll need the MMT as part of a fin can assembly to go into the approx. 163mm (6.4inch) OD airframe, which I'm also intending to roll myself with the same materials.

I like your suggestion on using CRs that hold the case without a MMT, but the big restriction for me is getting cases to utilise as the assembly/carrier tool. However, I'll put that idea into the mix when I get some TAPs on board (they're 1000-times more scarce than HPR motors in Oz!).

Having used about 1.5kg of the stuff already, I'd say the Bio-Epoxy is equally suited to wetting out fabrics as the West Systems epoxy I've used for the last few years. I've wetted out 300gsm F/Glass, braided carbon fibre, and now the 200gsm and 300gsm flax with it. It's only a tiny bit thicker when mixed and it applies in very much the same way by brush or mini-roller. It's is slower to go off than West, which can be handy, but if definitely takes two to three times longer to get to the "leather stage" and full cure.

However, because it's a new and unconventional epoxy, I'm interested in knowing more detail about the conditions its going to operate in (the case temperatures) and referencing this to the more conventional epoxies used for making MMTs.
Click to expand...
Most epoxies will benefit from post-cure heating. That usually means heating to above 100C for a specified time. You might consult the manufacturer for tech info on the process---time, temp, resultant properties.
 
Back_at_it said:
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.

View attachment 644547View attachment 644548View attachment 644549View attachment 644550View attachment 644552View attachment 644553View attachment 644554View attachment 644555
Click to expand...
I've still got a Blobbo. Need to dig it out and fly it again.
 
BrendanH69 said:
I like your suggestion on using CRs that hold the case without a MMT, but the big restriction for me is getting cases to utilise as the assembly/carrier tool. However, I'll put that idea into the mix when I get some TAPs on board (they're 1000-times more scarce than HPR motors in Oz!).
Click to expand...
The elevated temperature of the motor casing is a temporary thing. When this discussion started I was wondering if you could incorporate an insulating layer between the motor and the motor tube. The motor tube doesn't really pick up sideways forces from the motor so some kind of a polymer material might work.

The I read the suggestion to use centering rings with no motor tube and I thought that was a good idea. With no motor tube all of the thrust would go into one centering ring. If the builder wants to build a fin can then the motor tube would still be needed. So thinking further maybe use a motor tube larger than the motor, build the fin can around it, and put the insulating layer inside the inner tube. For that matter smaller centering rings could be placed inside the inner tube to center the motor and let the air space be the insulation.
 
bjphoenix said:
The elevated temperature of the motor casing is a temporary thing. When this discussion started I was wondering if you could incorporate an insulating layer between the motor and the motor tube. The motor tube doesn't really pick up sideways forces from the motor so some kind of a polymer material might work.

The I read the suggestion to use centering rings with no motor tube and I thought that was a good idea. With no motor tube all of the thrust would go into one centering ring. If the builder wants to build a fin can then the motor tube would still be needed. So thinking further maybe use a motor tube larger than the motor, build the fin can around it, and put the insulating layer inside the inner tube. For that matter smaller centering rings could be placed inside the inner tube to center the motor and let the air space be the insulation.
Click to expand...
My guess is that even flame resistant paper would be adequate insulation, if you could replace it easily when needed. I understand you can do that yourself with boric acid and borax, or maybe waterglass. Or use a thin layer of dog barf?

----------
Went to the field to try the rocket glider, but my igniters turned out to be unreliable. I must have tested the only good one at home, or maybe they age very quickly. (maybe two weeks)
 
Raining again (still?) so played with some paint mask designs for an Estes mini HoJo.

I wanted an homage to the Cox RTF that started me on all this but I also really like some of the HoJo roll patterns I’ve seen here, so…

Nosecone section pattern would be red, body pattern in black.

Too much?

IMG_5659.jpeg
 
jqavins said:
Yeah, when you put it that way, I'm not altogether sure he's picked one, just that it has to be bio, which puts out JB and most of the other epoxies on the market. The notion of fiberglass batts was my own; if you want something for insulation, why not use insulation? But the answer is that it's not a bio material.
Click to expand...
Hi Joe, I've already picked a bio-epoxy, bought some of it and used it too. Its what I'm using to laminate the plywood fin cores.

Its from a company called Change Climate who are based in Adelaide, South Australia. Here's a link to their site https://www.changeclimate.com.au/
Picture of two laminated fins is below, showing the 1.5kg kit I purchased from them, which I've now used up, mainly because I've been ultra cautious and generously wetting out the flax cloth so that it absorbs plenty of it into its fibres, so there is a fair bit of wastage at the moment. For laminating both sides of each fin, I'm mixing a total of 300gms, and when I weigh up the peel-ply and breather cloth afterwards, I'm calculate that I'm wasting about 200gms of that per fin.

IMG_0993.jpg
 
lr64 said:
My guess is that even flame resistant paper would be adequate insulation, if you could replace it easily when needed. I understand you can do that yourself with boric acid and borax, or maybe waterglass. Or use a thin layer of dog barf?

----------
Went to the field to try the rocket glider, but my igniters turned out to be unreliable. I must have tested the only good one at home, or maybe they age very quickly. (maybe two weeks)
Click to expand...

For Some reason, foil lined 24mm motor mount tubes have existed for decades. Not sure the real reason these were made? LOC had them in the early days which means Euclid Tube created them. BMS still has them, and so does Erockets. I have wondered for decades since the later 80s why this would be needed:
https://www.erockets.biz/semroc-hea...-lined-22-0-long-1pk-sem-bth-50mf-220-master/

1715415374197.png

"Special metal foil lining on the inside, reduces burn through from model rocket motor ejections"
Why only on 24mm tubes? Some other reason has to be for Euclid to have made these tubes.
 
BrendanH69 said:
Went to the McMaster-Carr site and selected two different packs of 10 temp stickers for about US$40. Went to check-out and shipping was US$57!!!!! :mad: They just need sticking in an envelope and popping into USPS international letter post! Even buying them from an Australian site would be cheaper!
Click to expand...
I know what your talking about. The package I sent to OZ today was an eye opener. I asked the PO clerk how much it was to get it there the fastest. WOW, you have got to be kidding. I wanted to mail it not buy it a seat on a private jet. So it's going the slow route.
 
Art Upton said:
For Some reason, foil lined 24mm motor mount tubes have existed for decades. Not sure the real reason these were made? LOC had them in the early days which means Euclid Tube created them. BMS still has them, and so does Erockets. I have wondered for decades since the later 80s why this would be needed:
https://www.erockets.biz/semroc-hea...-lined-22-0-long-1pk-sem-bth-50mf-220-master/

View attachment 644785

"Special metal foil lining on the inside, reduces burn through from model rocket motor ejections"
Why only on 24mm tubes? Some other reason has to be for Euclid to have made these tubes.
Click to expand...
 
lakeroadster said:
Click to expand...

That is a nice thread, but it really does not identify why Euclid made that foil lined tube. I can't believe that LOC told them they needed Foil lined 24mm tubes for staging when they didn't sell such rockets and they "seem" to be the first that had it on the market.

A guy that used hang around LOC and was in the SkyBusters rocket club worked at Euclid. I could have asked him back at the day but I was not curious about it back then.
 

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
306
ep29030
ep29030
kramer714
Student Rocket Programs - PDR Tutorial
Replies
0
Views
136
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
592
jqavins
jqavins

Latest posts

Back
Top