Overbuilding

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Erm back on topic...(wow this is the first thread that had inspired a rocket) I am building a rocket that uses a 29mm blue tube wrapef in 16oz fiberglass, fiberglass nose cone, and 1/8 G10 fins, there back on topic :D
 
Okay, I think referring to them as "lethal projectiles" is overreacting a bit.

Regardless, folks are obviously upset about the article. Why doesn't someone write a counter-point article, that has some references back to the original, and provides alternative solutions?

"In a previous issue of Sport Rocketry, and article was printed which recommended fiberglassing, etc. Rather than trying to build a bullet-proof rocket, I thought I'd demonstrate some alternative techniques to help address the same issues as the previous author."

Then, go on to make appropriate recommendations and show the various techniques.

-Kevin
A very good and very constructive suggestion, troj. I see this thread as containing a discussion of first impressions and reactions to the article rather than a coordinated, comprehensive response. The posts constitute chit-chat, which is always the bulk of the content on forums. I don't think that forum threads really lend themselves to formulating the kind of thoughtful, well-researched article that you are talking about. Forums are far more social than scholarly; nevertheless, I do like your suggestion.

Mark K.
 
Erm back on topic...(wow this is the first thread that had inspired a rocket) I am building a rocket that uses a 29mm blue tube wrapef in 16oz fiberglass, fiberglass nose cone, and 1/8 G10 fins, there back on topic :D

I really hope you're joking, because that's absolutely gorram liu-shu ridiculous. 16oz fiberglass is the sort of thing one might use on a minimum-diameter O or P motor rocket, not a 29mm one. Blue tube is Mach-capable right out of the box; you will almost never need to glass it. Ever. Plus if you build carefully, even thin-wall 29mm tubing can take the kick of a high-thrust G (the largest motor you can currently fly); LOC 29mm tubing certainly can. There's no reason for a FG nose cone; 29mm plastic cones are pretty tough. And 1/8 G10 is overkill as well.

What you're describing is what this thread is about: dangerous overbuilding. What you've described is not a rocket, but a javelin. If you want a javelin, go join the track team.
 
I really hope you're joking, because that's absolutely gorram liu-shu ridiculous. 16oz fiberglass is the sort of thing one might use on a minimum-diameter O or P motor rocket, not a 29mm one. Blue tube is Mach-capable right out of the box; you will almost never need to glass it. Ever. Plus if you build carefully, even thin-wall 29mm tubing can take the kick of a high-thrust G (the largest motor you can currently fly); LOC 29mm tubing certainly can. There's no reason for a FG nose cone; 29mm plastic cones are pretty tough. And 1/8 G10 is overkill as well.

What you're describing is what this thread is about: dangerous overbuilding. What you've described is not a rocket, but a javelin. If you want a javelin, go join the track team.

If you go to my thread about Fiberglassing (which includes an apogigy to all who run into my threads) I explicitly stated that it would only be for static display purposes and I just wanted to build somthing that would justify my threads here(when I start a thread I have a reason) and I would really like to learn this skill, and maybe even respark my intrest in airplAnes,who knows......
 
Erm back on topic...(wow this is the first thread that had inspired a rocket) I am building a rocket that uses a 29mm blue tube wrapef in 16oz fiberglass, fiberglass nose cone, and 1/8 G10 fins, there back on topic :D
Don't forget the spent uranium for the noseweight. Ted
 
Look I really don't wanna make a short range version of a V2 here, it is on my to build list
 
If you go to my thread about Fiberglassing (which includes an apogigy to all who run into my threads) I explicitly stated that it would only be for static display purposes and I just wanted to build somthing that would justify my threads here(when I start a thread I have a reason) and I would really like to learn this skill, and maybe even respark my intrest in airplAnes,who knows......
It's an unusual rationale, but hey, it's your money and your time. This is every bit your hobby, too, and you will do what you want to do. Good luck with your project (I mean that sincerely), and let us know how it works out.

Mark K.
 
I as well Mark! Model Rocket builder flyer since 1965.

Shouldn't we all be writing letters to the editor demanding retraction and an explaination from Sport Rocketry based strictly on the UNSAFE issues raised by Bullet-Proof building?

All the discussion here is prefectly health but I think unless Sport Rocketry is made aware of their blunder they will go along blindly following the HPR stressed mandate that seems to be coming from NAR HQ?

Simply complaining about it here isn't gonna help much as the masses of Sport Rocketry young and Old readers are lulled into believing Over-Building of this sort is perfectly fine....SEE it says so right there in the national magazine.
It will not take long for someone to be seriously injured or killed by one of the things...which are NO LONGER model rockets.... they have become lethal projectiles.

Surely you have to be kidding. What is so unsafe about flying a 4 ounce plastic rocket? The author of the article was merely demonstrating the effects of overbuilding a low power kit. Sure, it is ridiculous to glass a low power rocket to survive any landing to fly again. However, to declare this article the leading edge towards a trend to build small and dangerous rockets is absurd. I guess low power flyers never fly rockets over 4 ounces with plastic nose cones or fins otherwise, you are flying lethal projectiles.
 
It's an unusual rationale, but hey, it's your money and your time. This is every bit your hobby, too, and you will do what you want to do. Good luck with your project (I mean that sincerely), and let us know how it works out.

Mark K.

Thanks, I agree it is unusual,but I think it will be worth it in the long run, I could rip out the 18mm engine mount and put a 29mm into it with some mods. The real reason I'm doing this is because my friends still think it's common to launch a metal projectile out of your backyard.....hence why I won't launch it without some guts, I still have my Contest entry I need to get a start on...... But anyway I do many thing that others don't understand why, for example I have a strong intrest in machbusting, which in reallity has no reward,except when people say where the heck did that thing go! You can't prove machbusting with the 18mm once I fly (Mach attempt this summer)
as you can see I have an obsession with overdoing things, I put epoxy fillets on my machuster (I really wish I asked you guys) right now my obsession is overbuilding tommorow it might be drop off pod (strange ideas go through teenage minds) and I hope you all saw my apology on my fiberglassing thread
Best of wishes, Monty
 
Surely you have to be kidding. What is so unsafe about flying a 4 ounce plastic rocket? The author of the article was merely demonstrating the effects of overbuilding a low power kit. Sure, it is ridiculous to glass a low power rocket to survive any landing to fly again. However, to declare this article the leading edge towards a trend to build small and dangerous rockets is absurd. I guess low power flyers never fly rockets over 4 ounces with plastic nose cones or fins otherwise, you are flying lethal projectiles.

Abuserd? It inspired me to design somthing crazy just look at my description on an earlier post
 
If you go to my thread about Fiberglassing (which includes an apogigy to all who run into my threads) I explicitly stated that it would only be for static display purposes and I just wanted to build somthing that would justify my threads here(when I start a thread I have a reason) and I would really like to learn this skill, and maybe even respark my intrest in airplAnes,who knows......

I mean no disrespect, but i would love to have that kind of money for a "wall hanging". Why not invest in something that will fly and have fun with it? I like to do some odd thing to learn for to use somethings; like dipping the sharpened ends of feathers into epoxy to make fancy light weight hair sticks. Seems overdoing it to many people, but I love them. But they have a purpose, and not just a "wall-hanging".
 
I mean no disrespect, but i would love to have that kind of money for a "wall hanging". Why not invest in something that will fly and have fun with it? I like to do some odd thing to learn for to use somethings; like dipping the sharpened ends of feathers into epoxy to make fancy light weight hair sticks. Seems overdoing it to many people, but I love them. But they have a purpose, and not just a "wall-hanging".

Acttually (confessing one more time) I designed the rocket so it would fly safly on a estes C6-3 it clears a 6ft launch rod at about 27mph
 
How about carbon fiber covered with fiberglass?

I've made those for rockets that were expected to reach mach 3

This was for a university project and was going to fly on I think a Loki motor.
 
Last edited:
How about carbon fiber covered with fiberglass?

I've made those for rockets that were expected to reach mach 3

This was for a university project and was going to fly on I think a Loki motor.

Now how about a Kevlar-carbon fiber composite? Iv seen them on US composites
 
Surely you have to be kidding. What is so unsafe about flying a 4 ounce plastic rocket? The author of the article was merely demonstrating the effects of overbuilding a low power kit. Sure, it is ridiculous to glass a low power rocket to survive any landing to fly again. However, to declare this article the leading edge towards a trend to build small and dangerous rockets is absurd. I guess low power flyers never fly rockets over 4 ounces with plastic nose cones or fins otherwise, you are flying lethal projectiles.

A bullet regardless of size is still a bullet. Overbuilding like this is really harming our hobby. It's absurd not to reconize such a grave problem when it's staring us in the face. Our hobby has always had a great safety record specifically because we build models to do no harm or as little as possible. With is kind of overbuilding mainstreaming that will no longer be the case. It's time for the LPR community to push back hard against the demise of our hobby by the overbuilders and those who are trying to mainstream it as Normal practice. Exactly what such an article in a National MODEL rocket magazine does. It's only going to take a single accident with one of these overbuilt absurd bullets to start us down the road to excessive restricted hobby death. Keep your head in the sand if you wish, but i'm trying hard to get enough people to gather to demand a retraction and explaination for allowing such an article to be published.

Publishing a counter article is fine but it doesn't really call attention to and rebut to all those how have already seen it and like poor ScrapDaddy been pull in by it. Overbuilding must be minimized...no Stopped in it absurd tracks before it really hurts someone and the entire hobby along with it.
 
A bullet regardless of size is still a bullet. Overbuilding like this is really harming our hobby. It's absurd not to reconize such a grave problem when it's staring us in the face. Our hobby has always had a great safety record specifically because we build models to do no harm or as little as possible. With is kind of overbuilding mainstreaming that will no longer be the case. It's time for the LPR community to push back hard against the demise of our hobby by the overbuilders and those who are trying to mainstream it as Normal practice. Exactly what such an article in a National MODEL rocket magazine does. It's only going to take a single accident with one of these overbuilt absurd bullets to start us down the road to excessive restricted hobby death. Keep your head in the sand if you wish, but i'm trying hard to get enough people to gather to demand a retraction and explaination for allowing such an article to be published.

Publishing a counter article is fine but it doesn't really call attention to and rebut to all those how have already seen it and like poor ScrapDaddy been pull in by it. Overbuilding must be minimized...no Stopped in it absurd tracks before it really hurts someone and the entire hobby along with it.

it just seems intresting, I told everyone it would be static as it would revive heavy critisisum if I didn't,as of right now there is only a 65% chance it will even make it off the drawing board
 
Okay... seriously...let's get ourselves back on track.

I went ahead and sent an e-mail to the editor of Sport Rocketry on this article. I didn't go into a rant, I just stated my issues, and that I thought it was kind of a bad article, not worthy of Sport Rocketry. I will not put up the full article here, but here are the main points:

1 - Out of five launches, the author had three recovery failures. It's not a rocket problem, it's a rocketeer problem.
2 - In his report, Forty Years of Model Rocketry: A Safety Report, Mr. Stine points out that one of the four primary reasons for our hobby's fantastic safety record is the fact that model rockets are light weight and designed to "self-destruct" upon impact. The rocket in the article won't do that.
3 - The article was written by a LEVEL THREE certified rocketeer who can't get an Estes kit to work - that really casts doubt on our certification process.
4 - The NAR mambership, readers of Sport Rocketry, and th author woul dhave been far better served by an article on ROCKET REPAIR, or AVOIDING RECOVERY FAILURES.
5 - Despite all the time, effort, and money spent on this rocket, it still experienced a fin failure.

I am starting to think that parts of Stine's Handbook of Model Rocketry should be on the level one test.

I have also taken the step of writing an article promoting low power rocketry (while trying not to bash HPR). It is being proof read by some associates to be sure it's a worthy piece. Perhaps now that I am duly motivated, I'll look into common recovery failures and rocket repair (I have lots of experience with this one).
 
I have been in this hobby since the late '50's My first kit was a Model Missiles. In that time I have built and flown a lot of model rockets.

The safety issue was one I have always been proud of.

One of the earliest "tests" of the safety of this hobby that I can remember was of the tester fixing a pane of ordinary window glass directly over the launch pad and firing the model into the glass.

The model would crumble upon impact while the pane of glass remained intact.

To this day whenever I build a model I always think, "Will it pass the pane of glass test?

The model in the article would not!

You can get an Estes Guardian (the subject of the article) at Hobby Lobby with a 40% off coupon for $8 or so.

For the time and expense spent on "bullet proofing" an Estes Guardian you could probably buy and build a lifetime supply of them.

"Crash all you want, we'll just make more."

Just my $0.02
 
Okay... seriously...let's get ourselves back on track.

I went ahead and sent an e-mail to the editor of Sport Rocketry on this article. I didn't go into a rant, I just stated my issues, and that I thought it was kind of a bad article, not worthy of Sport Rocketry. I will not put up the full article here, but here are the main points:

1 - Out of five launches, the author had three recovery failures. It's not a rocket problem, it's a rocketeer problem.
2 - In his report, Forty Years of Model Rocketry: A Safety Report, Mr. Stine points out that one of the four primary reasons for our hobby's fantastic safety record is the fact that model rockets are light weight and designed to "self-destruct" upon impact. The rocket in the article won't do that.
3 - The article was written by a LEVEL THREE certified rocketeer who can't get an Estes kit to work - that really casts doubt on our certification process.
4 - The NAR mambership, readers of Sport Rocketry, and th author woul dhave been far better served by an article on ROCKET REPAIR, or AVOIDING RECOVERY FAILURES.
5 - Despite all the time, effort, and money spent on this rocket, it still experienced a fin failure.

I am starting to think that parts of Stine's Handbook of Model Rocketry should be on the level one test.

I have also taken the step of writing an article promoting low power rocketry (while trying not to bash HPR). It is being proof read by some associates to be sure it's a worthy piece. Perhaps now that I am duly motivated, I'll look into common recovery failures and rocket repair (I have lots of experience with this one).

Precisely the points we are planning on posting to Sport Rockety as an NAR Section (Group Objections) after discussion at our Club meeting Saturday.
Great points Ironnerd88! Hope your article is published not scrapped as many offered on the subject have been in the past.
 
Good work Ironnerd...

I agree with you, Micro, completely. Very good points in your post.

I don't have anything against HPR, but I'd just as soon see it stay 'on it's side of the fence' so to speak. G. Harry Stine had serious reservations about HPR and had to be 'won over' but he always seemed rather reticent of it, and for good reason (IMHO). I've seen more than a few near misses and some incidents that could have turned VERY ugly very quickly. I think that if it's something folks want to take the risks to pursue, they certainly should be able to and have the freedom to, but I DO think we need a distinct "wall of seperation" so to speak, (in the words of Thomas Jefferson) between HPR and LPR rocketry. That wall of seperation is becoming increasingly blurred all the time. This sort of 'overbuilding' just further blurs any distinctions between the two.

Sooner or later there WILL be a fatality as a direct result of a HPR flight, and when that happens, I hope that there is a wall of seperation distinctly visible to show to the regulators who will come riding in on white horses...

YMMV and all IMHO... OL JR :)
 
I've seen more than a few near misses and some incidents that could have turned VERY ugly very quickly. I think that if it's something folks want to take the risks to pursue, they certainly should be able to and have the freedom to, but I DO think we need a distinct "wall of seperation" so to speak, (in the words of Thomas Jefferson) between HPR and LPR rocketry. That wall of seperation is becoming increasingly blurred all the time. This sort of 'overbuilding' just further blurs any distinctions between the two.

I'll be honest, the scariest flight I've ever seen was a low power rocket on a D or E. It suffered a separation, and the upper section came in ballistic barely missing a spectator -- it left a scuff mark on her heel as it stuck itself into the ground. It was a rocket with an extremely pointed hard balsa nosecone that, had it her in the head, would've done some serious damage.

'tis why I feel that, for group launches, LPR pads should be moved out a bit -- for a half dozen or so, one pad, who are actively involved, it's not an issue.

My experience is that most bad recoveries (low and high power) happen relatively close to the pad. Increasing the distance a bit mitigates some of that issue.

-Kevin
 
Here's a different spin on using fiberglass in model rockets. I'm mentoring a TARC team in Connecticut. Right now, the field we fly from is still frozen if you go down a foot. As a result, there is standing water. Last year, they lawn-darted a rocket because repeated dunking in puddles had softened the glue and cardboard centering rings. Recognizing that they needed to build a rocket that was virtually waterproof, they changed construction to use epoxy for all joints and initially tried a Quantum Tube airframe which turned out to be too heavy. The current airframe is LOC tubing with a wrap of 2 ounce glass cloth. It's 2 ounce because that is what I had. (It seems that a prime requirement for construction materials is that it is available in my garage for the taking.) I have vacuum-bagging equipment from when I was playing around with RC gliders, so that got put into use bagging carbon fiber (you guessed it, I had some 2oz CF in my garage) onto the balsa fins. From a structural standpoint, that's overkill. .75oz glass would have waterproofed it just as well, but it looks cool. There is another benefit to a slight overbuild. The rocket is so rugged that it's not going to get dinged easily, so it will fly the same time after time after time, and that's what it takes to dial it in for TARC. Last Saturday they put in the first of their two allowed qualification attempts. They nailed the time, but went 17 feet too high for a score of 17. Oh yeah, the landing was a reenactment of the Apollo program : Splashdown, right in the middle of a puddle. The recovery crew waded in and pulled it out before water got to the altimeter.
 
Here's a different spin on using fiberglass in model rockets. I'm mentoring a TARC team in Connecticut. Right now, the field we fly from is still frozen if you go down a foot. As a result, there is standing water. Last year, they lawn-darted a rocket because repeated dunking in puddles had softened the glue and cardboard centering rings. Recognizing that they needed to build a rocket that was virtually waterproof, they changed construction to use epoxy for all joints and initially tried a Quantum Tube airframe which turned out to be too heavy. The current airframe is LOC tubing with a wrap of 2 ounce glass cloth. It's 2 ounce because that is what I had. (It seems that a prime requirement for construction materials is that it is available in my garage for the taking.) I have vacuum-bagging equipment from when I was playing around with RC gliders, so that got put into use bagging carbon fiber (you guessed it, I had some 2oz CF in my garage) onto the balsa fins. From a structural standpoint, that's overkill. .75oz glass would have waterproofed it just as well, but it looks cool. There is another benefit to a slight overbuild. The rocket is so rugged that it's not going to get dinged easily, so it will fly the same time after time after time, and that's what it takes to dial it in for TARC. Last Saturday they put in the first of their two allowed qualification attempts. They nailed the time, but went 17 feet too high for a score of 17. Oh yeah, the landing was a reenactment of the Apollo program : Splashdown, right in the middle of a puddle. The recovery crew waded in and pulled it out before water got to the altimeter.


I'm sorry but the story is still just another excuse.
Glass wasn't required at all. A simple coating epoxy would have done the same waterproofing job or better yet just soaking a paper/cardboard tube in CA would have the airframe holding up to as any puddles as you have. Even .5oz glass would still be overkill. Internat flyers use 40mm dia. single wrap .5oz or thinner models with great success that still self-destruct on impact as they are supposed to if something goes wrong. Dings don't effect well conceived model flights all that much, Making the model indestructable is counter to the spirit of the safety code we all swore to uphold. We can rationaize away just about anything, Overbuilding must be discouraged at all levels for the good of the hobby. Your team could and likely should be using light epoxy joints that wouldn't be effected by the moisture with or without a waterproof airframe.... I'd encourage without, as I've landed Plain painted models under Chute in a river before, retrieved it and that same model is still flying, more important to get that motor casing out before it swells in the mount.
We must at all power levels treat these models for what they are, that means protecting the user and unsuspecting public from a mishap.
I have models in my current flying fleet that are more the 28year old with more then 50 flights each. Not one has a single wrap of fibreglass on the body or fins. Overbuilding is simply unnecessary.

Kevin:
Your absolutely correct. Narhams has aways been in agreement with that point. Our LRP racks and pads are a minimum of 50feet for the controller and the spectators are kept a few feet further back then that. Shoot even my Micro Rack has 50 feet of cable LOL. Actually the further away for the pad we are the better view of the flights are observed.

It would really be great if each of you would write an e-mail or letter for that matter to the editor of Sport Rocketry ASAP. asking this really bad for the hobby article be retracted, or at very least rebuffed in an editorial by the editor explaining that these practices are counter to the good of the hobby.
I've done as much as I can until Saturday, Hopefully many others will join us.
 
"Back in the day," people used to fly M motors with nothing more than cardboard tubes. Now, many are convinced that you need 5 layers of fiberglass or 3 layers of carbon fiber to fly an M motor.

-Kevin

Amen there - I STILL use glass only sparingly, and on most HPR builds it is not needed and overkill.

I have flown cardboard, NO glass on some heavy duty L motors, and in most cases they fly fine ( one shred on a full progressive burn motor notwithstanding ) .

I can see no reason for the 3 layers of glass on a Modroc - one would be overkill, but THREE ?

~ AL

Fly high, fly SAFE
 
Here is the reality: I an not convinced that anything will happen unless NAR changes the safety code. My membership is in Tripoli so the "dog" that I have in this fight is rather marginal.

Here are some questions on where this may be going:


  • Do we want to launch frangible rockets only?


  • Who decides what rocket is frangible enough? RSO, LCO, or club


  • Do we want to put a limit on launch mass?


  • Do we want to put a limit on impulse?


  • Do you want to have rules that state "no reinforcement is allowed"?


  • Do we want to have a safety bunker at launches?

There is an inherent amount of risk in rocketry and there will always be. I am all for the minimizing of risk. The question is where do we draw the line.

I don't know if those who are doing LPR/MPR "upgrades" are all that many in number, and I am sure we all can supply our unscientific, anecdotal stories. But I suspect (my guess) is that it is well below 10% and possibly much lower percentage of all LPR/MPR launches.

For me, I would like the freedom to choose (I am a freeborn American and a Texan, who has served his country in uniform) where and how I manage my risks. Now, let freedom ring.

As you were.

american-flag-jet-2009.jpg



:2:

Greg
 
I LIKE overbuilding and HATE busted fins on landings even upon only PARTIAL recovery deployment (tangled chute, etc.), thusly I build strong and have been accused of flying TANKS. Rarely do I ever have broken components upon recovery however. BUILD STRONG LIKE OX, LAST LONG TIME !!!
If D-power or above, I use epoxy for ALL construction, period. Even low power gets EPOXY fillets, which results in a one-coat, smooth, even, STRONG fillet, the FIRST time , EVERY time !:neener:
 
I LIKE overbuilding and HATE busted fins on landings even upon only PARTIAL recovery deployment (tangled chute, etc.), thusly I build strong and have been accused of flying TANKS. Rarely do I ever have broken components upon recovery however. BUILD STRONG LIKE OX, LAST LONG TIME !!!
If D-power or above, I use epoxy for ALL construction, period. Even low power gets EPOXY fillets, which results in a one-coat, smooth, even, STRONG fillet, the FIRST time , EVERY time !:neener:

You're doing it wrong.

Wood glue, when bonding wood to wood, wood to paper, or other similar materials, is stronger than the materials being bonded. In other words, the epoxy gains you nothing but weight.
 
Bunk.
I have had several failures of wood glue joints and ZERO of epoxy since I switched to it about 15 years ago.
For me it seems to give a large margin of strength along with an easy one-pass smooth fillet instead of hassling with 3+ applications of titebond fillets that often are not nearly as smooth as one thin pass of 30min epoxy that weighs LITTLE more than 3 layers of titebond that shrinks unevenly.
 
Bunk.
I have had several failures of wood glue joints and ZERO of epoxy since I switched to it about 15 years ago.
For me it seems to give a large margin of strength along with an easy one-pass smooth fillet instead of hassling with 3+ applications of titebond fillets that often are not nearly as smooth as one thin pass of 30min epoxy that weighs LITTLE more than 3 layers of titebond that shrinks unevenly.

Believe me - I've shredded several rockets built with wood glue in which the fins came off, but the fin root was still attached firmly to the body tube. No matter what glue you use, you can't do any better than that for bond strength.

Now, I agree that epoxy is nice for finishing, but if you do them correctly, wood glue joints should be stronger than the materials being bonded.
 
Bunk.
I have had several failures of wood glue joints and ZERO of epoxy since I switched to it about 15 years ago.
For me it seems to give a large margin of strength along with an easy one-pass smooth fillet instead of hassling with 3+ applications of titebond fillets that often are not nearly as smooth as one thin pass of 30min epoxy that weighs LITTLE more than 3 layers of titebond that shrinks unevenly.

It's not bunk!
look at all the test results, they are not misleading for wood to wood, wood to paper white or yellow glues are superior.
As stated earlier I have many models build in the early 1980's (27 years ago, a few older still) that are still flying, looking pretty good and have more the 50 flights, built with Elmers carpenters yellow glue and/or Ambroid cement.
It is true, a quick topping fillet of thin 5 minute epoxy can make smoothing fin and Launch lug fillets easy but it's not for strength only easy of application and they are generally sanded down a good bit durning priming anyway.
Build light, match model/motor to the field conditions and have the proper recovery system you will not be damaging your models on landing. Adding a spill hole to your plastic parasheets will all but stop the oscillation that is responsible for so many broke or nicked fins. None of this is new technology...it's all in the Handbook.
OBTW the heavier the rocket the more likely we are to snap fins on landings if the model is not dampening out the chute spill oscillations. So Overbuilding INCREASES the likelyhood of model damage.
 
Last edited:
Back
Top