Fiberglass or not?

I will be launching a 1 pound rocket with an I49, and I have several q's about it.
1) Do I need to glass it? Max speed will be about 300 MPH, and it is Minimum Diameter.
2) How do you attach fins on a Minimum diameter HPR?
3)will Phenolic be strong enough?
Any tips would be appreciated...

I would not suggest flying a custom min. dia. rocket for your certification flight if that is what you have in mind, as it is more likely to break or get lost at high altitude. Also, the I49 requires electronic recovery. Are you set-up for that? Make sure you have the system down before attempting to certify.

No need to fiberglass... but surface mounting of fins does require some amount of reinforcement.

Make sure they are very straight, consider using an alignment tool or jig, and tack them on with crazy glue (CA is the official name.) This is not structural, but it will hold them in place. Then reinforce the fins at the attachment point with a layer of epoxy, called a fillet. This alone, as long as you sand the airframe and fin base, and use good strong epoxy, should cover slow motors like the I49.

Fast motors, supersonic flights, etc, will call for fin to fin fiberglass if you want to be safe. And I generally do prefer to be safe. If you want to push a 38mm minimum diameter rocket to it's limits, but dont want to spend the money on fiberglass or carbon, consider this one: https://www.redarrowhobbies.com/kits/Public_Missiles_model_rockets/cirrus.htm

This classic little rocket comes with fiberglass reinforcement for the fins, but still uses phenolic for the airframe. It is a jem.

Phenolic is PLENTY strong for most level 1 motors. The fin attachment is more of an issue here.

I personally only build fiberglass for level 1 and above, these days. Not because I have to, but because I like the confidence it gives you. One of my fiberglass rockets survived a really bad landing... with no damage, I get a 2nd chance whereas a paper rocket would have been destroyed. Also, the fiberglass allows future flights on very powerful motors. For example my 38mm fiberglass rocket is good for an I800 or any J motor. I would question (but not discount totally) the ability of a 38mm phenolic rocket, that is 6 feet long, to survive those flights.

Finally, and then Im done with the rant, if you are building a 38mm min dia rocket and are not worried about getting the max. altitude possible, consider this:

https://giantleaprocketry.com/pdf/acmefincans.pdf

These fin canisters are very easy to install on a rocket, and are ultra-strong. But they come at a cost, about $27, and also are not as aerodynamic as surface-mount fins.

I've flown a G-125 in a minimum diameter (29mm) phenolic airframe and it survived. Rocksim indicated it would be supersonic, so you should be fine at 300 mph with no glass. I used 1/16" fiberglass fins and slotted the airframe to install them, then built up modest epoxy fillets. I saw it deploy the streamer, but never found it.

Thanks, both of you. I am just planning several hpr rockets for after my cert

Keep in mind, the I49 requires electronic deployment. JRs cant use electronic deployment

Alex

blackbrandt said:

I will be launching a 1 pound rocket with an I49, and I have several q's about it.

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Your sig says you're going for a junior HPR cert. I'm guessing you don't realize you cannot fly with electronic deployment as a junior certified member? Item #2 under Junior HPR Participation specifically forbids it.

The qualification flight and all future flights must be single deployment only. This is due to regulatory requirements of ejection charges used in dual deployment systems. On board electronic devices are permitted as long as they are not used for deployment.

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1) Do I need to glass it? Max speed will be about 300 MPH, and it is Minimum Diameter.

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Need to? No. But strips across the fin roots will help reinforce the joint a bit. If your bonding is good and your fillets are good, you're fine.

2) How do you attach fins on a Minimum diameter HPR?

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Epoxy, and good fillets. If you're not going to use fiberglass to reinforce the joint, I wouldn't use CA to tack them on.

3)will Phenolic be strong enough?

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Plenty strong.

-Kevin

What are some long burn motors in the H and I range?

blackbrandt said:

I will be launching a 1 pound rocket with an I49, and I have several q's about it.

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As pointed out above, you can't use an I-49 of a Jr. L1 flight as it requires electronic deployment which is not allowed for Jr. L1 use. Long burn low thrust motors can be effected by wind much as like an E9 in a stiff breeze and end up flying horizontal rather than vertical. Not good for a cert flight.

1) Do I need to glass it? Max speed will be about 300 MPH, and it is Minimum Diameter.

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No. Glassing is not required for most L1 rocket. A minimum diameter rocket for a 38 mm motor has a 40-41 mm od and would look similar to a LOC Weasel. It would weight about 850 g loaded with a I-49, apogee over 8000' and have a top speed over 600 mph accoriding to my quick sim. A minimum diamter rocket on an I motor is not a good flight profile for an L1 cert flight that requires apogee deployment. Your rocket could drift 1 to 3 miles away from the launch pad. You stand a better chance of loosibg it than recovering it.

2) How do you attach fins on a Minimum diameter HPR?

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You surface mount the fins with epoxy. You can use a thin strip of fiberglas or a wood strip to reinforce the filet.

3)will Phenolic be strong enough?

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Phenolic is brittle. Plain old cardboard is a better choice.

Any tips would be appreciated...

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Use a 4" diameter rocket with a motor that provides a T/W ratio of 10 or higher for your cert fight. You will see the entire flight clearly as it will apogee at 1300'-1500' and will not drift sideways more than twice the apogee distance so you won't lookse it.

Find a mentor before you decide what to build.

Purchase and read Modern High Power Rocketry 2nd by Mark Canepa

blackbrandt said:

What are some long burn motors in the H and I range?

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If you insist look at the combined list. My advice is not to use a long burn motor in a minimum diameter motor, but pick a 4" rocket like this 4FNC example that weighs between 4 to 6 pounds with the motor. Pick a motor with am average thrust of 150 Ns or higher. A higher thrust shorter burn motor will lift off quicker, be less effected by wind, and fly straighter.

Bob

An additional trick for strengthening fin attachment on a min diameter rocket is to make little epoxy rivets. Drill a series of small holes in the body tube where the root chord of each fin will attach. Then mount each fin with epoxy rather than tacking on with ca. When it sets you file down all the little epoxy dimples on e inside of the airframe and fillet as usual. Migt be overkill and probably would work better on cardboard than phenolic, but another technique I have seen/used.

While it's true that you can't use electronic deployment as a Jr L1, you can find an adult who is regular L1 or higher to fly it for you or help you prep and then put their name on the flight card. This should be easy since if you're doing JR L1 you're working with an adult HPR flier anyway and is standard protocol with most clubs. As a former youth flier of high power (and now certified adult), you can PM me with any questions you might have about rockets or how to get them flown them safely and legally while under 18.

David Harris
TRA L3

No, of you are a junior Level 1, you cannot use electronics, period. It is against the rules.

This is a significant limitation as opposed to not getting the junior cert, and just flying with a parent.

-Kevin

Are any of you from a club in NC or VA

If you want to launch a minimum diameter for your Jr L1 go for it. I did it for my 18+ L1 with DD, but if you use an Aerotech 2 grain, @1.5lbs, you'll get about 3000ft, or on a CTI 2 grain you'll get about 4500ft-5000ft.

It's much more exciting than a KISS rocket that you know will work :roll:

troj said:

No, of you are a junior Level 1, you cannot use electronics, period. It is against the rules.

This is a significant limitation as opposed to not getting the junior cert, and just flying with a parent.

-Kevin

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But the post from Marsman said to fly it under the adults's name, and if the adult's name is on the flight card, it is the adult's flight, and the adult's legal responsibility and liability if something goes wrong. And I don't see how that is against the rules.

Or are you saying that rules actually say that if my son gets an L1 cert, and he helps me prep a flight with my name on the flight card that has electronic deployment, this cannot be done under the rules, but it could be if he didn't have an L1 cert? If this is the case, where is the line drawn? If he helps me unpack the kit and is on the field when I fly the rocket, is this against the rules as well?

sam_midkiff said:

But the post from Marsman said to fly it under the adults's name, and if the adult's name is on the flight card, it is the adult's flight, and the adult's legal responsibility and liability if something goes wrong. And I don't see how that is against the rules.

Or are you saying that rules actually say that if my son gets an L1 cert, and he helps me prep a flight with my name on the flight card that has electronic deployment, this cannot be done under the rules, but it could be if he didn't have an L1 cert? If this is the case, where is the line drawn? If he helps me unpack the kit and is on the field when I fly the rocket, is this against the rules as well?

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The NAR rules for junior HPR certified fliers specifically state

The qualification flight and all future flights must be single deployment only. This is due to regulatory requirements of ejection charges used in dual deployment systems. On board electronic devices are permitted as long as they are not used for deployment.

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So, if your son gets a junior HPR certification, he has to operate within the confines of the program he chose to participate in.

The NAR junior HPR Certification Policies are pretty cut and dried on the matter.

Skip the junior certification and just fly rockets with your son, if he wants to be involved with rockets that use electronic deployment. But if he wants the junior certification, then he has to follow the rules of that program.

-Kevin

troj said:

Skip the junior certification and just fly rockets with your son, if he wants to be involved with rockets that use electronic deployment. But if he wants the junior certification, then he has to follow the rules of that program.

-Kevin

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Exactly... imho there is something to be said for waiting until you are 18 to cert level 1 anyway. It is a personal choice... but you can enjoy mid power for a while and pace yourself.

The way I interpret the rules are that if the Junior is flying the rocket, then it has to be single deploy. But if the adult is flying the rocket, then it's the adult's rocket and it can be dual deploy. There aren't any rules about who can build a high power rocket, just who can fly one. If blackbrandt wants to get Junior HPR certified, I see no problem with him building a rocket and giving it to his dad or mentor to prep at the launch site and fly. He can even advise on the prep if he wants. It's no different than letting an adult who only flies model rockets watch/talk to you as you prep your high power rocket.

I'd just say ask your local RSO(s) and see what they're comfortable with.

blackbrandt, what you can do is fly your minimum diameter on a streamer recovery and fly it single deploy. Regardless of this debate, you're allowed to use a radio tracker since it's not used for deployment. It won't drift that much farther on a streamer than on a dual-deploy parachute, and if you have a tracker on board it doesn't really matter except for a longer walk.

Marsman said:

The way I interpret the rules are that if the Junior is flying the rocket, then it has to be single deploy. But if the adult is flying the rocket, then it's the adult's rocket and it can be dual deploy.

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I don't understand how you can "interpret" this sentence that way:

The qualification flight and all future flights must be single deployment only

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If you choose to participate in the junior certification program, then you must follow all the rules governing it.

Remember, our launch insurance is based on folks following the rules.

-Kevin

Marsman said:

I'd just say ask your local RSO(s) and see what they're comfortable with.

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Back in the day, an RSO let me fly G125s before I was 18. It is on you to follow the regulations as the RSO is not going to catch everything. The fact is, having an adult fly a rocket with electronics will not work for jr 1 cert. They can legally fly it, but that wont be a cert flight. The RSO has the final say on a flight, but does not have the final responsibility that a rocket is safe or legal. Check the level 2 test for more on this.

Marsman said:

blackbrandt, what you can do is fly your minimum diameter on a streamer recovery and fly it single deploy. Regardless of this debate, you're allowed to use a radio tracker since it's not used for deployment. It won't drift that much farther on a streamer than on a dual-deploy parachute, and if you have a tracker on board it doesn't really matter except for a longer walk.

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If a fin pops off, or the airframe cracks, you wont certify. Few 38mm rockets can recover on a streamer, and the RSO WILL be concerned about a 40 fps recovery.

I believe that if it's for a Certification flight, it doesn't really matter if built by minor and prepped by adult, or vice-versa, the cert flight for a Junior L1 must be single-deployment w/no electronic charges, period.
if the rocket was registered on flight card with adults name on it, the cert flight would go to the adult anyway and no Jr L1 given to the minor.

This is a saftey measure to ensure that NAR members under 18 can still enjoy the satisfaction of achievement in HPR, without breaking any laws regarding handling/use of black pwdr among minors.

BlackBrandt...there are lot's of great things you can still do to achieve a high level of excellence in sport rocketry and challenging kits for HPR without the need for dual deploy for a cert flight. I feel if you have to have an adult build/prep/or register the rocket for you, then it takes away alittle of the satisfaction of "I built this myself". However it is necessary for an adult to supervise the built/prep of HPR. but you should want the flight card registered to you!

Good Luck with your choice on your Jr L1.......we need more youths to get involved in Rocketry for the hobby to survive! and HPR is a great way to get the word out that rockets are not all toys!

You can get a Wildman dragon or wildman jr and fly it on a CTI H54. Simple, happy flight.

FWIW, I fully support him certing on a single deploy fully Jr L1 qualifying rocket. What I'm advocating him do is after the cert flight build a dual deploy rocket in conjunction with his dad/mentor and have the dad/mentor handle all of the 'regulated' black powder and prep and fly the rocket.

I agree with troj and New Ocean that he can't fly dual deploy on the cert flight or on any of his other flights by himself as a JR L1...I'm just saying he can be involved in a dual deploy flight as long as it's not 'his' rocket and an adult L1+ is prepping and flying the rocket.

I also fly a 38mm minimum diameter single deploy and on a streamer and it works great...fins have carbon fiber layups but I think that fiberglass would be fine if done well.

Jr. L1s can't fly any high power rocket by themself until they are 18 and become a Sr. L1. Not only can they not handle BP, they can't handle the high power motor either. A Sr. L1 or higher NAR member must assemble and insert the motor into the rocket and insert the igniter and connect it to the launcher.

Bob

Hi folks, i am on a cell phone so typos might happen.
The NAR rules are quite clear and not open to extentions.

JR L1 can not use blackpowder, ematches or electronic deployment as stated in the rules.
I am under an extreme travel work sched for the next 7 to 8 days and wont be able to comment more until i return. The TRA analogy does not work for NAR jr l1and does not apply.

Art Upton
NAR HPR services chairman

Ok, so we've beaten this dead horse repeatedly.

I'm sure the young lad realizes he can't cert dual deploy and has rethought his motor selection (and maybe even his design)....so.......

let's see the build thread!

cbrarick said:

I'm sure the young lad realizes he can't cert dual deploy and has rethought his motor selection (and maybe even his design)....so.......

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It's not the cert flight that was in question; it's the subsequent flights.

-Kevin

troj said:

It's not the cert flight that was in question; it's the subsequent flights.

-Kevin

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Hi Kevin, all NAR JR. L1 flights flown at NAR launches must be flown the same way as the JR L1 cert flight to be covered by the NAR.

Just caught this before my next leg of the journey.

Art