Technique building history?

I was gifted an older 29mm mount 4" build. Retention of the era is masking tape, and recovery attachment is by looped metal cable to flat half inch elastic strap. On tube fin mount. Not plywood ring motor mount...this is old school by appearance to me. (Of course I don't know how old is actually old school) launch buttons apparently didn't exist...6mm+ lugs are on this 53" tall orange army missile.

I'm pretty new to higher powah building, so im looking for knowledge of how we built, 20-30+ years ago so I know just how old of a style this is.....I'm wondering about mount rings of the day, (obviously not laser cut plywood rings) were they super heavy cardstock ply? The cable is looped through the top ring and who knows if these rings can take a good deployment or a 29mm shot today. If in doubt, I could shove some new rings on top of the old tube onesand on bottom and have a modern eyebolt and retention method.

So what did we use back then, in steps. The build histories are interesting.

20 years ago my dad and Iwere building with kevlar and nylon primary shock cords attached to the motor mount. At the time I remember "old" rockets built they way you said.

Scrapmaster87 said:

20 years ago my dad and Iwere building with kevlar and nylon primary shock cords attached to the motor mount. At the time I remember "old" rockets built they way you said.

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So I'm looking at near 40 years or so. I'll poke a bit into the rings and see how solid they may be.

If you post a pic we could maybe take some guesses. I don't know enough about e.g. ACE, Composite Dynamics, USR, AAA but someone else here likely does.

Didn't NCR aka North Coast Rockets use (and still does) a steel cable recovery anchor system? They also made some military scale and scale like models as well.

I think Rich may be right. How about a picture or two, Rob ?
Can you find your model here ? https://www.ninfinger.org/rockets/catalogs/NCR1989CAT/NCR1989.pdf

Pictures will come later this week when i get home. By all research it appears in exact dimension to the Mad Cow patriot missile (like on apogees page) but with older build parts in 29mm mount size and wood strips up the sides in white, like their picture shows.

The retention is pretty much that gorilla mount in a 4" to 29mm centering ring.

Forensically, I did drill a small hole into the aft ring, and it's not wood. it's a very thick sort of grey cardstock. Possibly 1/8" or more like 3 mil. Probing in to that hole with a small metal tent stake, there s 2 rings total on the 16 inch long motor tube. Looking in the motor tube, it has seen quite a bit of ejection charge residue. Given this, I'm not too sure of the mount strength but I think it would still handle F50's just fine, and occasional G78 single use stuff, but also some lower power 29mm reloads. So I'm leaning towards re-rigging with new heavy duty elastic strap on that cable and either continuing with tape, or popping on an estes retainer and giving it a whirl. I'm not doing delayed release or serious high power launches with this but if I did, I would replace the mount.

According to Tim at Apogee in a article some years ago, we builders have a strong tendency to underestimate the strength of centering rings, and/or overestimate the strength they really need, and consequently overbuild. Obviously this rocket has flown before and is still in one piece, so wouldn't sweat the rings, or much of anything else. That gorilla shock cord mount would make me nervous with a cardboard centering ring, even a super thick one; can you tell if the forward ring has been upgraded to wood?

Some folks still use 1/4" launch lugs.

MPR isn't HPR. Relax and launch that puppy.

Some kits still use steel cable for recovery harness attachment.

https://www.cosmodromerocketry.com/AerobeeHi.html

Fiberboard rings for 29mm is more than strong enough, even for H motors. 1/4" launch lugs are common. 3/8" less common. Our club still has 1/2" rods in our trailer because some kits still use them.

Friction fit motors on 29mm is not unheard of but it is uncommon. I built a kit 2 weeks ago that was 4x 24mm and 1x 29mm and all 5 motors are masking tape thrust rings and friction fit.

It could be 40 years old....or 4, you really don't know unless you know who built it.

jqavins said:

According to Tim at Apogee in a article some years ago, we builders have a strong tendency to underestimate the strength of centering rings, and/or overestimate the strength they really need, and consequently overbuild. Obviously this rocket has flown before and is still in one piece, so wouldn't sweat the rings, or much of anything else. That gorilla shock cord mount would make me nervous with a cardboard centering ring, even a super thick one; can you tell if the forward ring has been upgraded to wood?

Some folks still use 1/4" launch lugs.

MPR isn't HPR. Relax and launch that puppy.

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I drilled a small hole in the rear, saw the shavings and couldn't tell what it was but it was thin. So I was worried. The mount tube also had a few blisters inside in the exhaust residue, so I just got cautious and removed the mount. They were phenolic rings, plastic like. After removing them, I realized they were rather solid and the gorilla mount would have held given that the strongest 29mm reload would only put this at 2500 feet. A g76 hobby rms should post 1000+ ft. It was around 800-900 grams. But I decided to redo the mount with through wall new fins and .125 wood rings for a strong bottom end. Adds about 200 grams in the end with a good solid recovery rigging. Something I can level1 with.

heada said:

Some kits still use steel cable for recovery harness attachment.

https://www.cosmodromerocketry.com/AerobeeHi.html
......

It could be 40 years old....or 4, you really don't know unless you know who built it.

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It's late 80s early 90s. It's got age on it and the guys collection had quite a lot of vintage Estes. A teacher who retired about 6-8 years back

With a 29mm mount on a 4" rocket white glue is fine, 30 min. epoxy was hardcore back then. The fins will not strip off from acceleration or speed. The biggest problem was fins breaking off from a hard landing (chute didn't open fully) or zippering the tube (the delay was guesstimated and delays were not adjustable, you had to buy a motor within 2 seconds of your guess). Electronics have fixed the delay problem and kevlar blankets keep chutes safer. Bigger, lighter chutes are common with a chute release; less drift. Back in those days, the trend was from wide elastic to nylon strapping to reduce zippering. A longer cord meant you didn't need a shock cord, just retention.

I know its just my opinion, but I wouldn't pass a rocket thru the RSO with a 29 mm mmt built with white glue. Sorry, but at least use some thick superglue. But for me epoxy is the only way to go for high power. And don't kid yourself, 29mm in a 4 inch rocket, you're going to get into HP size and weight real fast if you're not already there. So ditch the white glue and build like a high power rocketeer with epoxy please.

Good idea to replace whatever those 4" x 29 mmt centering rings were with plywood.

But back to the original question, back in the early 90's there were several HP kit manufacturers that used steel cable connections to centering rings for recovery harness connections. I've got an original THOY Pheonix (from Ypsilanti Michigan) that has its original steel cable thru the top centering ring for recovery harness attachment. But the centering rings were 1/8 inch plywood. I don't know of any manufacturers that were using steel cable thru any kind of fibre/cardboard/plastic centering rings. But the only kits I bought in those days with steel cable recovery harness attachments were high power kits.

Does anybody know who is the manufacturer of your rocket? That would really help as would pictures of the actual rocket.

Brad

RocketRev said:

I know its just my opinion, but I wouldn't pass a rocket thru the RSO with a 29 mm mmt built with white glue. Sorry, but at least use some thick superglue.

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The joints on centering rings, both MMT to ring and ring to body tube, are loaded mainly in sheer. Super glue sucks rocks in sheer. I agree that epoxy would be best, but I'd far rather see white glue than super glue. And with TB I wouldn't be too concerned, assuming there are good fillets. (But I'd still use epoxy on my own such builds.)

this is getting epoxied in, jbweld on the mount tube and tw fins jb to mount tube, then epoxied elsewhere, epoxy clay filets. itll be able to take abuse, which is what its for. RMS hobby reloads and occasional 29/360 shots. For white glue, Titebond3 is really good stuff and gets into the pores well, and in this scenario, I wouldn't have any issue with it given i'm using 3 rings and would still jb the fins to the motor tube for the localized heat. Anyway, It's building up solid.

Rob40 said:

For white glue, Titebond3 is really good stuff

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Titebond 3 is an aliphatic resin wood glue. Closer to a 'yellow' glue than white elmers glue

RocketRev said:

I know its just my opinion, but I wouldn't pass a rocket thru the RSO with a 29 mm mmt built with white glue. Sorry, but at least use some thick superglue.

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on a paper and wood rocket white glue is likely a better bond than super glue

When I'm using cyanoacrylate adhesive on model rockets, I am first off using the very THICK super glue. One can create far more than adequate fillets with this stuff especially when you have some ZIP available. I've also used various things for increasing the strength matrix of the CA fillets from baking power (uh works in very small amount on small rockets) to chopped fiberglass and chopped carbon fibre, as well as very thin fiberglass cloth. In my experience it works great. The very thin fiberglass cloth and thick CA make an excellent repair combination for healing old wounded model rockets that I just can't give up on for whatever reason.

And I too have used the Titebond 3 yellow glue for model rockets. But getting into higher thrust motors just begs for stronger adhesives in my opinion and the initial question has to do with getting into high power rocketry. And suddenly its a whole new ballgame when it comes to the forces working on the air-frame and fins of the rocket. I've seen too many even Titebonded cardboard and plywood rockets fail from those very same forces working on the air-frame under high power rocket motor pressures.

Model Rocketry? Titebond is great.
Mid-Power Rocketry? Titebond becomes questionable.
High Power Rocketry? Titebond is inadequate.

Just my two cents worth from my 50 plus years of building and flying rockets of all sizes. And I know that there are some who disagree and that's your privilege. Just don't ask me to pass a High Power Rocket thru my RSO station if its been built with white glue or even Titebond.

Brad

RocketRev said:

. Just don't ask me to pass a High Power Rocket thru my RSO station if its been built with white glue or even Titebond

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With all due respect to you experience and observations, isn't that a bit much of a blanket statement? For a minimum diameter screamer I wholeheartedly agree, but based on technical data and the properties of the material, not on opinion.

For anything subsonic or even pushing transonic a bit, the properties of plywood, Loc tubing, and wood glue (formulated to bond to those natural composite materials) are just fine. There have been L3 certifications and mach busters with TBII. (And I've seen some 'Strong composite layups!' that absolutely flubbed before they hit 600mph)

Give the science a chance Rev, poor build skills can trash even the "best" materials. Please don't let the priviledge of being an RSO get clouded by personal tastes.

That's my opinion as a Rocketeer and an engineer.

RocketRev said:

...

Model Rocketry? Titebond is great.
Mid-Power Rocketry? Titebond becomes questionable.
High Power Rocketry? Titebond is inadequate.

Just my two cents worth from my 50 plus years of building and flying rockets of all sizes. And I know that there are some who disagree and that's your privilege. Just don't ask me to pass a High Power Rocket thru my RSO station if its been built with white glue or even Titebond.

Brad

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Since we're all free to express our opinions here (more or less ) I'll add mine.

I'm very glad not every RSO shares your opinion. And No, I'm not giving back my Level 2 I got with a LOC Doorknob built with Titebond II as the primary adhesive.

Titebond II, cross-linking polyvinyl acetate according to this website:

https://www.titebond.com/product/glues/2ef3e95d-48d2-43bc-8e1b-217a38930fa2

Rob40 said:

Pictures will come later this week when i get home. ...

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Rob40 - did you get any pictures of the mystery kit yet ? Or maybe you already identified it ?

I too will add my concurrence to that of SamB and Nytrunner, TBII or most any yellow wood glue is good enough WHEN USED PROPERLY and the rocket is kept within the performance envelope of the materials its bonding.

I've been flying HPR since 1989.

Recovery mount, in 1989, LOC used a nylon string embedded in epoxy like the Kevlar string embedded in epoxy as shown in an earlier post.
I've used the LOC method, same except using TN shock cord material, steel cable through the top CR and looped around the motor tube, Kevlar strap epoxied to the motor tube, and eye bolt or U bolt in the top centering ring. I currently use the LOC with TN, Kevlar on motor mount, or eye bolt in top CR (with glass reinforced ring and fender washers). Elastic works for rockets weighing up to 2-3 lb., above that, TN is best.

Rails didn't become common until about 10 years ago. Rods work fine as long as they're big enough. 1/4" rods are only good up to mid power, above that you need to go to at least 3/8", although I prefer 1/2". I still have a lot of rockets with lugs. My 54mm Deuce uses a 3/4" x 10 ft rod and I have a rocket that uses a 1" rod.

Glue. If the rocket is cardboard & wood, yellow wood glue works fine if the part fit is good. White glue will get brittle after a few years. If there are gaps to fill, 5 minute epoxy is stronger than the materials. Fiberglass rockets will need a better epoxy.

Motor retention. I still use tape in several of my rockets, especially with paper motor tubes. I always build with about 3/4" of the motor tube sticking out behind the rear CR. Before reloads (introduced in 1990), you had to build a thrust ring with masking tape. Lightly friction fit the motor then wrap tape over the motor tube - thrust ring joint. Works for reload cases also. I use Aeropak retainers on fiberglass rockets.

I commented earlier on that Gorilla shock cord mount, how I wouldn't be comfortable with a steel cable bearing on the centering ring unless the ring is plywood, and not altogether happy about long term wear even if it is. I moment ago I had a thought that would make me more comfortable (and, I admit, quite possibly for no other reason). A steel grommet. Or if the ring is too thick for a grommet that I can find (in which case I'm pretty sure it's for no other reason) then a washer epoxied to the bottom of the CR aligned with the hole to reinforce that edge.

samb said:

Titebond II, cross-linking polyvinyl acetate according to this website:

https://www.titebond.com/product/glues/2ef3e95d-48d2-43bc-8e1b-217a38930fa2

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Whoa, I was under the mistaken impression that TBII was alphatic resin. Looking at the Titebond site, seems that original Titebond is aliphatic resin (class wood glue), TBII is PVA, and TBIII is "Advanced Proprietary Polymer".

OK, this doesn't happen often, but I am ready and willing to be re-educated. When I saw Titebond 2, like Neil_w, I also figured that it was just an upgraded alphatic resin.

I've never seen or used either TB-2 or TB-3, which apparently are NOT alphatic resin.

But now I'm learning that instead of mere alphatic resin, TB-2 is PVA while TB-3 is an "advanced Proprietary polymer." I'm going to have to learn more about these two adhesives.

So until I learn otherwise, I am giving you all, more than just a little give on the use of TB-2 and TB-3 in high power rocket building.

But I will still NOT personally pass a simple alphatic resin adhesive built rocket for High Power. Yes, I know there will be those who have seen some TB-1 built high power rockets that have worked just fine. My difficulty is that I've seen alphatic resin adhesive fail way too many times with high power rockets under high power rocket motors.

Seriously, thanks for the education guys. I may be an "old dog" but I've never been afraid to learn "new tricks."

Brad