New to the forum, first HPR build, LOTS of questions

[dbrownsd]

Hi all!!

This being my first post here I thought I'd give a little background before I get to my questions....

I used to build rockets like mad... About 20 years ago. Estes skill level 5 was an easy build at that time. Then life happened.

Now I have a 6 year old son who is entranced with rocketry. He wants to be an aerospace engineer when he grows up so he can build things that go into space. As short of an attention span as he has anything that has to do with rockets captivates him. Six hours to build a rocket lego set? Daddy's not allowed to take a break till it's done. 15 minute video of accordion folding a Mylar streamer? Won't look away because ROCKETS!!

This summer I introduced him to model rocketry, and re-introduced myself to it. He LOVES it. We've built three rockets in the last two months with several more slated for this winter.

That said I figure I need to stay a step or two ahead of him so I'm going for my HPR L1 cert next summer. I just bought the kit I'm going to use which is the...
Drum-roll please... LOC Hi-Tech rocket. I got it for $70, and it'll fly on engines as low as E (200ish ft according to rocksim) all the way through I motors. It can also be set up for dual deployment when I'm ready to take that step.

In going over the instructions, everything seems pretty straight forward except one thing which I kind of question. The shock cord mount. It has a length (haven't measured it yet) of I'm assuming nylon braided cord for the shock cord mount, and an elastic shock cord (1/2" wide). The instructions are to fold the shock cord mount in half, tie a 1" loop in the end, and tie knots 1/4" from the loose ends. Get some masking tape and stick them down inside the air-frame. Epoxy the ever living $)%& out of it..... Done.

Wow... That seems like a lot of hoping the epoxy soaks into the cardboard from the inside just right in order to hold it. Also, how should I be tying a 1/2" piece of elastic to the mount? Just a standard double knot and some CY to seal it?

Is there a better way to do the shock cord mount / cord. My thoughts (based on some research / youtube / "this just isn't right") are that I should take a length of Kevlar thread (size / length unknown), mount the end down into the engine mount, use a Nomex wad slid down as far as I can get it and call it a day.

Second question.
This kit comes with a 1/4" launch lug. Do I need to look at converting it to a rail launch? I have plenty of ideas on how to do that properly.... Is it possible to have both on the same rocket? The launch lug for low power flights, and on the other side (It's a 3 fin rocket so 1/3 of the way around) have rail buttons for the high power flights?

Third question.
What considerations do I need to account for when building a rail launch pad. Here's what I'm thinking. A wooden box 24" x 18" and about 8" deep. If I need I can rig up some leveling legs (about 20" long) that fold into the long sides for transport, but unfold for support (I don't really think I'd need them tho). I'd cover the top wood piece with a piece of plate steel for a blast plate. I'd embed a drill chuck in the top so I could mount any size rod up to and including the 1/2" rail mount rods that are out there, and hinge the lid so not only can I tilt the rod down for loading, but have a storage box for all my launch kit. Some nice handles on each end for easy transport and.....

Last question.
I live in the wonderfully flatish state of South Dakota (I'm outside of Sioux Falls). According to NAR and Tripoli there are no chapters out here. The NoDak chapter links to to dead websites. I'm planning on heading down to Nebraska when I'm ready to do my cert flights, but are there any rocketeers in Eastern SD, SW MN, NW IA or NE NE that can direct me to areas that once I get my HPR I can use to launch (Given all the FAA waivers are in place). Speaking of FAA waivers, I'm having a hard time finding if it's altitude based or power based or both. I've read all the info I can find and can't find anything concrete other than NS based and distance from an airfield.


Well, wall 'o text complete.... Please be gentle, I'm new again in an entirely different level.

Pics of kiddo's builds including NARTREK builds coming soon....

 

[troj]

First, welcome to the forum! Your experience with your son is how I got back into rocketry....except that my kids lost interest, and I stayed hooked. My oldest three have little, or no interest, but my youngest loves it.

There's a new program on the forum that looks like a good fit for you -- Take a look.

Wow... That seems like a lot of hoping the epoxy soaks into the cardboard from the inside just right in order to hold it. Also, how should I be tying a 1/2" piece of elastic to the mount? Just a standard double knot and some CY to seal it?

Is there a better way to do the shock cord mount / cord. My thoughts (based on some research / youtube / "this just isn't right") are that I should take a length of Kevlar thread (size / length unknown), mount the end down into the engine mount, use a Nomex wad slid down as far as I can get it and call it a day.

Don't use CA on the shock cord -- it will make it brittle in that spot. Believe it or not, a knot is all that's required -- I typically use a couple overhand knots. The LOC mount isn't optimal, but to start out with, it's fine. A better option is an eyebolt in the forward centering ring, assuming the tube is large enough you can get your hands in there to tie a knot. I'm also not fond of the elastic, and use tubular Kevlar, instead.

This kit comes with a 1/4" launch lug. Do I need to look at converting it to a rail launch? I have plenty of ideas on how to do that properly.... Is it possible to have both on the same rocket? The launch lug for low power flights, and on the other side (It's a 3 fin rocket so 1/3 of the way around) have rail buttons for the high power flights?

Lugs work; I only use buttons. On smaller rockets, lugs are fine. As they get heavier, rod whip becomes more of an issue.

What considerations do I need to account for when building a rail launch pad. Here's what I'm thinking. A wooden box 24" x 18" and about 8" deep. If I need I can rig up some leveling legs (about 20" long) that fold into the long sides for transport, but unfold for support (I don't really think I'd need them tho). I'd cover the top wood piece with a piece of plate steel for a blast plate. I'd embed a drill chuck in the top so I could mount any size rod up to and including the 1/2" rail mount rods that are out there, and hinge the lid so not only can I tilt the rod down for loading, but have a storage box for all my launch kit. Some nice handles on each end for easy transport and.....

That would work, or you can use a camera tripod, or sawhorses, or....

I live in the wonderfully flatish state of South Dakota (I'm outside of Sioux Falls). According to NAR and Tripoli there are no chapters out here. The NoDak chapter links to to dead websites. I'm planning on heading down to Nebraska when I'm ready to do my cert flights, but are there any rocketeers in Eastern SD, SW MN, NW IA or NE NE that can direct me to areas that once I get my HPR I can use to launch (Given all the FAA waivers are in place). Speaking of FAA waivers, I'm having a hard time finding if it's altitude based or power based or both. I've read all the info I can find and can't find anything concrete other than NS based and distance from an airfield.

Your best bets are going to be Nebraska (where I am; we launch south of Lincoln), or Minnesota (south of Minneapolis). There's also a club in the Des Moines area.

Waivers are based on rocket weight and motor size.

-Kevin

 

[dbrownsd]

I'm also not fond of the elastic, and use tubular Kevlar, instead.

Tubular? Can you provide dia and source?

Lugs work; I only use buttons.

Have you ever tried, or seen, both on the same rocket to account for different power engines? Should I just go one or the other flat out?

Your best bets are going to be Nebraska (where I am; we launch south of Lincoln), or Minnesota (south of Minneapolis). There's also a club in the Des Moines area.

Are any of these available outside of club events? Lincoln is about 4 hours from me. If I wanted to go down an launch on a "random" weekend... Could I?

Waivers are based on rocket weight and motor size.

That basically confirms what I found online. The part I don't understand is a light rocket that can go over a mile and mach + on a F motor doesn't require a waiver. But a rocket that is heavy but only goes 1200' (nowhere near air traffic) on a H or I motor does?

 

[bobkrech]

A lightweight rocket on an F is not going to be moving very fast at altitudes where aircraft fly.

The FAA is concerned about rockets being a hazard to aircraft in-flight. The kinetic energy of a rocket impact weighing not more than 1.5 kg propelled by not more than 125 g of propellant is comparable to a large bird impact and is not likely to do severe damage to the aircraft. Heavier rocket impacts can damage an aircraft in-flight and therefore require a waiver so that the FAA can issue a NOTAM to warn pilots of the rocket launch activity.

As the airspace is shared, a rocket launcher is legally obligated to scan the sky for aircraft before launching, prohibited from launching into the path of aircraft, and prohibited from launching into clouds. Following the procedures makes the chance of encountering an in-flight aircraft vanishingly small.

Bob

 

[Zeus-cat]

You will need to go to a NAR or Tripoli launch to get your high power certification, but once you have it you can always launch near where you live. That assumes you can find a place to launch high power rockets; farms are great for this. You can call in a waiver just for yourself. Better yet; start a club in your area.

 

[Spurkey]

First off, welcome to the forum! This is a great place to learn about the hobby. It's easy to get overwhelmed by the amount of information to process when building a rocket, always keep in mind that there usually isn't "one right way" to do something and that many have personal preferences when it comes to techniques each with their own pros & cons.

Is there a better way to do the shock cord mount / cord.

Certainly. I don't like using elastic in shock cord, especially if you're considering working your way up to high-powered motors with this kit. When the parachute comes out at apogee when the rocket's travelling at speed, the elastic stretches to its limit and then snaps back. Often the nosecone impacts the body tube, if you search for "Estes ding" on this forum you'll find many, many accounts of this happening. Estes nosecones & body tubes get dinged up because Estes a) uses full elastic cords b) uses soft balsa for nosecones. There's also the potential of the parachute fouling with all that bouncing back & forth.

As for better ways, here are a couple:
https://www.madcowrocketry.com/v/vspfiles/files/pdf/bomarc.pdf
https://www.madcowrocketry.com/v/vspfiles/files/pdf/patriot26.pdf
https://www.apogeerockets.com/Advanced_Construction_Videos/Topic (videos 061 & 087)

If you're looking for sources for better shock cord material, nearly all of the rocketry vendors carry some variants:
https://www.apogeerockets.com/Building_Supplies/Parachutes_Recovery_Equipment/Shock_Cord
https://www.giantleaprocketry.com/products/components_recovery.aspx#Shockcords

Second question.
This kit comes with a 1/4" launch lug. Do I need to look at converting it to a rail launch?

If you're looking to fly G-motors & above I would strongly recommend adding a set of rail guides in the manner you described: 120° away from the lugs. Keeping the lugs gives you greater flexibility for launching at small club launches where a rail might not be present. As with anything in this hobby there are many different types, I would suggest picking one of the cheaper ones to get some experience with them:

https://www.apogeerockets.com/Building_Supplies/Launch_Lugs_Rail_Buttons/Rail_Buttons
https://www.giantleaprocketry.com/products/components_launch_systems.aspx
https://www.coastrocketry.com/Launch Lugs.htm

The Apogee videos include ways of installing them.

Lastly, check out many of the "build threads" on the forum, they're forum threads where someone documents how they are building a particular kit. If you can find one close to the kit you're currently building it's a great place to ask questions about why the builder chose to do things they way they did.

 

[Handeman]

Welcome aboard!

The advice you've gotten so far is spot on. You don't need a FAA waiver until the launch weight (rocket + motor) is over 3.33 lbs (1500 g) OR the propellant weight is more then 125 grams. That means you could launch your LOC Hi-Tech with a 38/240 case and a Aerotech H123W without a waiver and be legal. You would have to have your L1 cert to buy and use the H motor, but that is a separate issue. And that combination should get well over 3,000 feet.

I have a rocket about the size of the Hi-Tech that has both 1/4" lugs and rail buttons. The kit came with the lugs and I added the buttons 120º away when the club got rail pads. That is probably not the best set up for high performance, but it still gets almost out of sight on large H motors and is very versatile.

I use the 1/8" tubular kevlar for all my rockets that size. It is plenty strong, packs small and is relatively low cost.

Keep asking question, searching the forum, and most of all, keep launching rockets!

 

[Rocketjunkie]

I have a High Tech in my fleet. I have modified it for dual deploy and it weighs 28 oz ready to fly except motor. My shock cord mount is like the LOC but I used a short length of 3/8" nylon strap (from eBay). My shock cords are the same nylon strap, 20' for apogee, 6' for main. I also enlarged the chute to 30". You will need an adapter for most flights as the rocket has a 38mm mount. If you build it completely stock per instructions you should end up at about 24 oz. I use the stock 1/4" launch lug that came with the kit.
I get just over 1000 feet on a G54, a little over 2000 feet on 29/240 or 38/240 reloads, around 3000 feet on full H motors, and nearly 6000 feet on a 580 N-s I85.

 

[RadManCF]

Your best bets are going to be Nebraska (where I am; we launch south of Lincoln), or Minnesota (south of Minneapolis). There's also a club in the Des Moines area.

There are three clubs in MN, MASA, the club I belong to, flies in Nowthen, which is east of Elk River, a few miles north of I94. Tripoli MN flies in North Branch, MN, about 45 min north of Minneapolis/St. Paul. Tripoli Southern MN flies in the southern part of the state, in the Austin area.