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benrichardson

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Hola again. Just wondering what materials do you guys find best for the fins? I don't know whether to go down the route of wood like balsa... Or try fibreglass as I have a tad experience with it?


Thanks hope you can help again!
 
Basswood is a good next step, Balsa-Ply another. Birch can be "iffy" these days, much of birch is now birch veneer over a poplar core and much of it will warp and the worst times. Hobby Birch has pretty much escaped that but it will still warp. I've use cheap Luan Philippian mahogany door skins painted with epoxy so that it soaks in.

But if you have experience with fiberglass then go with that. There are sources of real thin waferglass and circuit board material that has worked fine over the years.
 
Basswood is a good next step, Balsa-Ply another. Birch can be "iffy" these days, much of birch is now birch veneer over a poplar core and much of it will warp and the worst times. Hobby Birch has pretty much escaped that but it will still warp. I've use cheap Luan Philippian mahogany door skins painted with epoxy so that it soaks in.

But if you have experience with fiberglass then go with that. There are sources of real thin waferglass and circuit board material that has worked fine over the years.

Ditto Dave's Post;
Add to that "built up" Heavy Cardboard or 1/64", 3/64th" & 1/32" Light Aircraft Ply fins can be quite large for MPR & Clustered Models without adding a ton of unnecessary mass.

Fiberglassing is a technique best left to the HPR crowd. "Glassing" LPR or even MPR model rockets is just overbuilding that should be avoided where possible. Our LPR/MPR Models are intended to absorb kinetic energy not transfer it to an object being stuck. Bullet proofing models with fiberglass while it may seem like a way to strengthen our models is just not a good thing for our hobby.

167-lp02-sm_Laser-X 3D staged Liftoff_06-10-95.jpg
 
Ditto Dave's Post;
Add to that "built up" Heavy Cardboard or 1/64", 3/64th" & 1/32" Light Aircraft Ply fins can be quite large for MPR & Clustered Models without adding a ton of unnecessary mass.

Fiberglassing is a technique best left to the HPR crowd. "Glassing" LPR or even MPR model rockets is just overbuilding that should be avoided where possible. Our LPR/MPR Models are intended to absorb kinetic energy not transfer it to an object being stuck. Bullet proofing models with fiberglass while it may seem like a way to strengthen our models is just not a good thing for our hobby.

I cannot disagree with you more on the fiber glassing of LPR.

At first glance, the uninitiated or inexperienced builder might agree wholeheartedly with your assessment. You hear "fiber glass" and "rockets"... you think of the big HPR monster tubes and think beefy fins! The HPR guys are busting Mach speeds and have birds that weigh dozens if not hundreds of pounds! They use 6, 7 and 9 oz. fiberglass cloth in multiple layers and wraps. This of course adds the desired strength these folks are looking for, but with the added weight. Not a problem for HPR... just use a bigger and more powerful motor!

With the lower power weight is a serious factor! An 18mm Estes C6 tops out at 4 oz. max lift-off weight. So heavy glass isn't an option. When fiber glassing LPR I typically use very light weight .75 oz cloth in a single wrap around a cardboard tube or 1 layer per side of a balsa fin. This adds virtually no significant weight with much added strength and resilience. This gives your rocket a much greater lifespan and durability. There is a fine line between adding weight vs. the need for stronger materials due to it's weight. Sort of a double edged sword so to speak... this however does not cross that line.

There are also many benefits to glassing.

For Body tubes:

Much added strength
Cover spirals and requires much less sanding!
Tubes gain some elasticity and resist dents and crushing

Balsa Fins:

Extreme strengthening (as light as bass, stronger than ply)
Seals the grain.

Let me put it this way. I could smack you over the head with one of my 20" long, 2.75 oz., BT-60 rockets using the fins and the rocket would be fine. You on the other hand would get an "owie"!

Fiberglass materials are generally used in many products because of how strong they are for being so "light" in weight!

I don't glass every rocket I build. It does add a little extra time. The results however are spectacular!

Give it a try!


Jerome :)
 
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I cannot disagree with you more on the fiber glassing of LPR.

At first glance, the uninitiated or inexperienced builder might agree wholeheartedly with your assessment. You hear "fiber glass" and "rockets"... you think of the big HPR monster tubes and think beefy fins! The HPR guys are busting Mach speeds and have birds that weigh dozens if not hundreds of pounds! They use 6, 7 and 9 oz. fiberglass cloth in multiple layers and wraps. This of course adds the desired strength these folks are looking for, but with the added weight. Not a problem for HPR... just use a bigger and more powerful motor!

With the lower power weight is a serious factor! An 18mm Estes C6 tops out at 4 oz. max lift-off weight. So heavy glass isn't an option. When fiber glassing LPR I typically use very light weight .75 oz cloth in a single wrap around a cardboard tube or 1 layer per side of a balsa fin. This adds virtually no significant weight with much added strength and resilience. This gives your rocket a much greater lifespan and durability. There is a fine line between adding weight vs. the need for stronger materials due to it's weight. Sort of a double edged sword so to speak... this however does not cross that line.

There are also many benefits to glassing.

For Body tubes:

Much added strength
Cover spirals and requires much less sanding!
Tubes gain some elasticity and resist dents and crushing

Balsa Fins:

Extreme strengthening (as light as bass, stronger than ply)
Seals the grain.

Let me put it this way. I could smack you over the head with one of my 20" long, 2.75 oz., BT-60 rockets using the fins and the rocket would be fine. You on the other hand would get an "owie"!

Fiberglass materials are generally used in many products because of how strong they are for being so "light" in weight!

I don't glass every rocket I build. It does add a little extra time. The results however are spectacular!

Give it a try!


Jerome :)

Jerome:
You make my point exactly: All that Extra strength makes the model more Dangerous not just more durable. I use single wrap .5oz fibreglass body tube models for Competition models but not for super strength rather super light weight. But I can get very close to the same minimum mass by using Tracing vellum instead of Glass and epoxy making the model Less of a potential projectile. The main difference is these super light weight PD and SD models will not penetrate a body or damage property if one happens to hit someone or something.

It's all about overall Hobby safety. NOT making models that won't suffer minor flight damage on landings. Glassing over cardboard tubes in considered Overbuilding no matter how else you try to justify it. It's totally unnecessary and a DANGER to yourself and others.
If your Flying on your own property, Alone by yourself, do whatever the Heck you want but Stop telling people this sort of construction is good for the hobby... It is NOT.

I'm still flying stock models built Way back in the early 80's some of which have 50 or more flights. Are they as pretty as they were went first finished? NO but they are perfectly flightworthy even though they are Only Cardboard, Balsa, Elmer's glue and some primer and Paint.

Stop trying to make this pig look like a silk purse. Fiberglassing over Standard .013 and .021 wall cardboard tubes should be considers a crime in my book since you making a semi-safe hobby model into a potential letal projectile.

That's all the time I'll waste trying to educate you folks on the BANE of OVERBUILDING. But it is a problem that if not greatly reduced will become a major problem for the hobby very shortly as a whole or at very least cause more local and federal Law intervention, restrictions and/or out right ban for something that really is totally unnecessary. Repair you minor flight and landing damage with normal methods instead of building Bullet proof projectiles that may curtail or in the worst case out right cancel everyone's ability to fly model rockets at all.
Remember: The General public has NO understanding of what our "Models" can do, Just an accident or two and Authorities will take action none of us want. Build Light and fly!

40mm-10mm-ss_1-wrap .56oz FibreGlass bodytube_03-94.JPG

FibreGlass_Carbon Fiber & .25mil mylar_08-27-06.jpg

218c_MM .125A 25cm SRD,PD or SD Fiberglass_07-14-09.JPG

218d_MM .125A 25cm x.375 SRD,PD,SD &Alt Fibreglass_07-14-09.JPG

216-Mk2-4_MM Mk4,3 & 2 Vellum models_02-18-13.jpg
 
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Well said Jerome. Today I glassed a 28" BT-50 Tube with 2oz. cloth. Here are the before and after weights:

24mmMDTRI 001.jpgAfterGlassWeight24mmMD 001.jpg
 
A lightweight FG airframe is not a dangerous projectile. I do custom FG tubes using 0.75 to 1.4 oz cloth in a variety of weights...they are generally lighter and more flexible than paper tubes. An implication that such tubes are somehow more dangerous than a regular BT-5 or BT-20 is simply false. Blanket statements about "FG == overbuilding" and "glassed paper tube == lethal projectile" in the LPR realm are just not correct. There is no data to support such a claim...if there was then FG would be disallowed in the safety code. Disclaimer - I fly HPR too and am pretty used to 2-10kg rockets in addition to LPR comp.
 
John,

I understand you have a lot of experience.... I can respect that... but I do not have to agree with you.

You also fundamentally used both sides of the argument. You stated you have used fiber glass for it light weight properties and also talk about it being a "heavy" projectile. We are talking a few grams or ounces, All within the prescribed safe range for "model" rocketry. You are holding on to the illusion that fiberglass construction is like using lead. Even if it was lead weight, 1 lb of lead weighs the same as 1 lb of feathers! lol Using your logic then, clustering motors should be outlawed as well.. Surely adding additional motors increasing the rocket's impulse is a "bane" in your book when you can simply use a single higher impulse motor barely adding any significant weight?! Right? No?

There is nothing "unsafe" about launching lightly glass "model rockets"....... Estes makes dozens of rockets with plastic parts weighing more than most of my glassed birds.

I have been called a "Rules Nazi" and a "Weight Nazi" many times in these circles. Safety is an utmost concern of mine. I advocate "SAFE" flying.

This is not my first rodeo either. I'll take my 35+ years of "progressive" rocket and hobby building vs. your 50+ years of 1960s, antiquated way of doing things any day of the week.

Part of the enjoyment people get out of this hobby is the variety of building techniques. Learning new ways, different and maybe better than before. Enjoy your hobby the way you want to! Nobody is forcing you or anybody to fiberglass a rocket. I just say be safe if you do... follow the rules... and have fun! Do that, and I won't rain on anybody's parade. Be unsafe, break the rules or ruins others having fun doing the first two... well I'll be all over on that!

Jerome :)
 
One of our local hobby shops sells some pretty decent plywood in a variety of thicknesses. That's what we use, along with my daughter's TARC team. 1/8" is a pretty good compromise between weight, stiffness, and durability. If you are doing TARC (which I'm inferring from previous posts), we've found this year that it's really important to have a very durable rocket. You want to be able to launch it a dozen or so times to dial in altitude and hang time. Every time you make repairs, it monkeys just a bit with the results and it takes another launch or two to adjust. I would highly recommend using a slightly thicker wall than the standard Estes BT tubes. We did not find it that important to be lightweight for this year's rules, although that may change with next year's.

As for the overbuild/optimize argument upthread, I'd just say that there is no One True Way to build a rocket, any more than there is One True Way to have a relationship with another person. Every launch is a risk, which is managed with good practices from the various safety codes. My Estes Wizard could do a lot of damage to a person if it came in ballistic, and it's a lot harder to see than a TARC-style rocket.
 
Hola again. Just wondering what materials do you guys find best for the fins? I don't know whether to go down the route of wood like balsa... Or try fibreglass as I have a tad experience with it?
My personal favourite is balsa laminated with paper. Simply trace round the fin on plain simple copier/printer paper, flip the fin over its leading edge and trace round it again, then cut out the resulting shape. Spread white glue all over both sides of the fin (some people like to dilute the glue with water to make it easier to spread), then wrap the paper shape over the fin leading edge to cover both sides. Smooth out any bubbles, then put the fin between a couple of pieces of greaseproof paper and put something heavy on top of it, e.g. a stack of books. Doing both sides at once this way reduces the risk of warping, which is likely if you only paper one side at a time so only one side gets coated with glue which then dries.

Once the glue is fully dried, dribble thin cyanoacrylate glue around the edges, let it dry, then sand the edges. This seals the edges so the paper is less likely to peel off.

Net result: a fin which is significantly stronger than plain balsa, doesn't need multiple coats of sanding sealer, and doesn't upset the people who hate fibreglass. :lol:
 
Jerome:
Lets be clear here: I never said the amount of added mass was or is the problem. What I said and will repeat is Glassing over our Standard .013" or .021" Craft body tubes ADDS "UNNECESSARY Mass" to the model.
As you mentioned and I agree every gram of additional mass added to a LPR model directly effects its potential Altitude. If Your glassing over your standard tube those few grams may mean you'll need some additional nose weight or Larger Fins to get the CP/CG back to where it should be...That's MORE UNNECESSARY Mass.

But the overall Mass of the models is NOT, repeat NOT THE Issue.
Making our LPR and MPR Body tubes "stronger and more durable" you are removing one of the properties that the Craft body tube was chosen for. That is it absorbs impact energy by accordian crumpling rather then Transferring the energy by Penetrating the object or person.
Let me Illistrate: Several years ago at one of our club public monthly sport launches one of your newer, Less experienced adult rocketeers decided to build and fly a Styrofoam Shuttle mounted on a 36" BT-50 booster tube capped with a PNC-50AD Plastic Nosecone. Because he had used a coupler between the two 18" pieces of tubing he added a wrap of 2oz fiberglass cloth. He explained later that was Just to make it stiff. Long story short launching this model on a C6 the model immediately tipped horizontal flying under power into the tent of another club member sitting preparing his model for launch. The booster Struck him in the thigh just below the groan. imbedding the NC and forward tube more then 4" deep. Requiring an emergency trip to the hospital, 6hrs of surgery and months of recovery time. During the follow-up investigation we learned had the same NC been used on a standard BT-50 it would likely have penetrated the skin but NOT completely penetrated the thigh. Why? because the standard BT-50 would have Accordian Crumpled and/or split absorbing most of the energy rather then simply transferring it. Had this booster hit our member in the chest He'd be dead.

While it is perfectly true that at this time Fibreglass, Graphite and Carbon Fibre laminating materials are fine by the safety code. It must also be noted that these materials have been in use in NAR and FAI competition flyers for DECADES. They are/were NOT use to strenghten anything, They are used to reduce the overall Mass of 40mm x 500mm FAI international models. Back in the 90's we were using very light carbon fiber over 1/20" Contest balsa compressed into a laminate .005 and .010" thick super stiff, ultra light weight fin materials. Again used to REDUCE the overall Mass of the models being built. Some years later this sort of material was produced as "WaferGlass" in .005" to .020" thickness. You now call this material G-10. The HPR folks as mentioned earlier looking at mock+ are using this stuff in thickness with mass we'd never even consider.
Point being even with all these exotic materials the Overwhelming concern was to make the models LIGHTER while still allowing them to crumple on impact if necessary. Safety was ALWAY foremost.

I'm glad you used the term "Progressive" Meaning Liberal or "Doing anything I want, with what I what, anytime I want". This has been an on-going concern since the early 90's.
IT is the progression of little things making the overall safety of the hobby worse. With most new builders finding STUFF on forums like this one and seeing some of the outragoues posts on U-tube it's no wonder these things spiral out of control.
Someone sees an international flyer laying up Ultra light single wrap .56oz glass & Mylar PD,SD or HD bodies and says Hey thats a great Idea! I don't have a mandrel but I could just lay the glass over a standard body tube....and the problem begins. NO research, No Science, just Hey that looks good.
If you are truely a SAFETY First guy, YOU MUST NOT tell people glassing over cardboard tubes it a good practice. Unless it is somehow possilble to build in a forward break-away crumple zone that will absorb most of the models kinetic energy should it hit something or someone.

With the current Safety code it could be possible to use and fly Graphite Kite spars and Carbon Fibre Arrow shafts. Most do not Why? Because the pose a danger. We are not allowed to fly even Thin Wall Aluminum tubing for the same reason "All These material DO NOT Crumple on impact they Penetrate, just like Glassed cardboard body tubes do.

It is my hope that at some point both the NAR and Tripoli Safety committees will recognize the potential danger of flying these Laid-up composite Bodies for what they are "Leathal Projectiles" and adopt some common sense revisions to the use of said materials. Til then I'll keep right on spreading the Conservative Safety first Always "antiquated" Word.
 
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The force of an object is subject to its mass and speed (F=M*A). The damage done to a person being hit would be the same whether an object was made out of mostly cardboard or iron weighing the same. Your "crumple zone", like on a car, would need to be on the person, not the projectile to save a more internal part or organ. Yout logic is based on imperial data. Nothing more.

The hobby we enjoy has an element of danger. We launch long pointy objects high in the air. The idea is to get them back, safely and do it in a safe manner. Your example of that person getting hit is a tragic accident. How you described it has nothing to do with a wrap of fiber glass. What you described is more likely the result of unsafe launching practices. First off, either the rocket was not designed or tested for stability or the conditions of the launch were not safe. Any of these violate the safety code and should not have happened.

5. Launch Safety. I will use a countdown before launch, and will ensure that everyone is paying attention and is a safe distance of at least 15 feet away when I launch rockets with D motors or smaller, and 30 feet when I launch larger rockets. If I am uncertain about the safety or stability of an untested rocket, I will check the stability before flight and will fly it only after warning spectators and clearing them away to a safe distance. When conducting a simultaneous launch of more than ten rockets I will observe a safe distance of 1.5 times the maximum expected altitude of any launched rocket.

&

9. Launch Site. I will launch my rocket outdoors, in an open area at least as large as shown in the accompanying table, and in safe weather conditions with wind speeds no greater than 20 miles per hour. I will ensure that there is no dry grass close to the launch pad, and that the launch site does not present risk of grass fires.


It is also not a good idea to have your spectators or participants in the line of fire or path of the rockets. This includes recovery areas.

Just so everybody is clear on this. NAR liability insurance will not cover accidents that find the rocketeer or club a in violation of the safety rules.

Jerome
 
Many actual companies already make mid-power kits that are made of Fiberglass, and have been doing so for a long time. Badazz even had kits made of PVC, hardwood and Metal components. Micromiester must think that Eric at Badazz is the ULTIMATE SUPER BANE of the Hobby:y:. If I wanted to use a Rocket to actually penetrate something I'de go with one of his Kits.
There is no excuse for building unstable kits that fly out of control. The basics of stability are not "Rocket Science", oh wait, they are, but they are so simple a baby should be able to figure them out.
I use sims now because they are fun, but I can make a model fly straight without them.
If someone is building unstable models that are going to hurt someone because they are unstable, then they are going to hurt someone regardless of what they are made of.
I'de rather be hit by my lightweight glassed models than one of my older, heavier papered or basswood models if I had to be hit by one at any kind of velocity.
It's sad that this conversation has to happen, as Fiberglassing is here to stay, whether Micromiesters head explodes or not.
Have we helped the OP get his question answered?
 
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...Many actual companies already make mid-power kits that are made of Fiberglass, and have been doing so for a long time...

Many also make kits that use TTW fin mounting...

The HORROR!!!:y:
 
Jerome:
Lets be clear here: I never said the amount of added mass was or is the problem. What I said and will repeat is Glassing over our Standard .013" or .021" Craft body tubes ADDS "UNNECESSARY Mass" to the model.
As you mentioned and I agree every gram of additional mass added to a LPR model directly effects its potential Altitude. If Your glassing over your standard tube those few grams may mean you'll need some additional nose weight or Larger Fins to get the CP/CG back to where it should be...That's MORE UNNECESSARY Mass.

But the overall Mass of the models is NOT, repeat NOT THE Issue.
Making our LPR and MPR Body tubes "stronger and more durable" you are removing one of the properties that the Craft body tube was chosen for. That is it absorbs impact energy by accordian crumpling rather then Transferring the energy by Penetrating the object or person.
Let me Illistrate: Several years ago at one of our club public monthly sport launches one of your newer, Less experienced adult rocketeers decided to build and fly a Styrofoam Shuttle mounted on a 36" BT-50 booster tube capped with a PNC-50AD Plastic Nosecone. Because he had used a coupler between the two 18" pieces of tubing he added a wrap of 2oz fiberglass cloth. He explained later that was Just to make it stiff. Long story short launching this model on a C6 the model immediately tipped horizontal flying under power into the tent of another club member sitting preparing his model for launch. The booster Struck him in the thigh just below the groan. imbedding the NC and forward tube more then 4" deep. Requiring an emergency trip to the hospital, 6hrs of surgery and months of recovery time. During the follow-up investigation we learned had the same NC been used on a standard BT-50 it would likely have penetrated the skin but NOT completely penetrated the thigh. Why? because the standard BT-50 would have Accordian Crumpled and/or split absorbing most of the energy rather then simply transferring it. Had this booster hit our member in the chest He'd be dead.

While it is perfectly true that at this time Fibreglass, Graphite and Carbon Fibre laminating materials are fine by the safety code. It must also be noted that these materials have been in use in NAR and FAI competition flyers for DECADES. They are/were NOT use to strenghten anything, They are used to reduce the overall Mass of 40mm x 500mm FAI international models. Back in the 90's we were using very light carbon fiber over 1/20" Contest balsa compressed into a laminate .005 and .010" thick super stiff, ultra light weight fin materials. Again used to REDUCE the overall Mass of the models being built. Some years later this sort of material was produced as "WaferGlass" in .005" to .020" thickness. You now call this material G-10. The HPR folks as mentioned earlier looking at mock+ are using this stuff in thickness with mass we'd never even consider.
Point being even with all these exotic materials the Overwhelming concern was to make the models LIGHTER while still allowing them to crumple on impact if necessary. Safety was ALWAY foremost.

I'm glad you used the term "Progressive" Meaning Liberal or "Doing anything I want, with what I what, anytime I want". This has been an on-going concern since the early 90's.
IT is the progression of little things making the overall safety of the hobby worse. With most new builders finding STUFF on forums like this one and seeing some of the outragoues posts on U-tube it's no wonder these things spiral out of control.
Someone sees an international flyer laying up Ultra light single wrap .56oz glass & Mylar PD,SD or HD bodies and says Hey thats a great Idea! I don't have a mandrel but I could just lay the glass over a standard body tube....and the problem begins. NO research, No Science, just Hey that looks good.
If you are truely a SAFETY First guy, YOU MUST NOT tell people glassing over cardboard tubes it a good practice. Unless it is somehow possilble to build in a forward break-away crumple zone that will absorb most of the models kinetic energy should it hit something or someone.

With the current Safety code it could be possible to use and fly Graphite Kite spars and Carbon Fibre Arrow shafts. Most do not Why? Because the pose a danger. We are not allowed to fly even Thin Wall Aluminum tubing for the same reason "All These material DO NOT Crumple on impact they Penetrate, just like Glassed cardboard body tubes do.

It is my hope that at some point both the NAR and Tripoli Safety committees will recognize the potential danger of flying these Laid-up composite Bodies for what they are "Leathal Projectiles" and adopt some common sense revisions to the use of said materials. Til then I'll keep right on spreading the Conservative Safety first Always "antiquated" Word.



Shame someone got their "Groan" pierced.
 
Many also make kits that use TTW fin mounting...

The HORROR!!!:y:

I saw a Snail crawling along the edge of a Razor, and he carried with him a model rocket with TTW fins that were Glassed....The Horror... The Horror....
 
Micromiester, I have a lot of respect for your skills, and learn a lot from your posts.
I just want to make it clear that I can see where you are coming from, but that we'll just have to agree to disagree on some stuff.
I don't fly in areas that have "Bystanders", so I don't worry about a "Model Rocket Massacre". The thought never even crosses my Mind to be quite honest.
 
My advice on fins is to use like carpenters glue on the wood fins. You could also use Testors glue on the fins as well. I hope my advice is helpful?

Xan
 
My advice on fins is to use like carpenters glue on the wood fins. You could also use Testors glue on the fins as well. I hope my advice is helpful?

Xan

Wood Glue aka yellow wood glue for wood fins(common brands are Elmers Carpenters and TiteBond) it grabs very quick when applied in thin layers making long couplers difficult to insert. White Glue of which the best known is Elmers Glue All (not School Glue) works the best for gluing tube couplers since it doesn't seize/grab as fast yellow glue does. Testors works for certain plastic fins and two piece nose cones, but not on wood. CA (aka superglue) mostly in the thin variety is great for tacking parts together and "hardening" cardboard tubes which make them tougher for minimal weight. Epoxies while unnecessary on most LPR rockets do have uses, I use them mainly when repairing damaged rockets using very long couplers since they don't grab as fast as the yellow and white glues. I have slid couplers as deep as 6 inches into a tube with yellow glue but it was pretty tough, and I get it wrong more often than I care to admit.
 
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