The Path to HPR?

I understand that there are no hard and fast rules for this, but I'm curious if there is a generally accepted path to high power rocketry. What are the skills and fields of knowledge that you would want someone to attain before they consider going for L1 certification?

Use sound building techniques for L-1 type rocket.
Learn Cp to CG relationship for safe,stable flying and design. [center of pressure CP center of gravity CG] this determines whether additional nose weight need to be stable, a non issue with most kits...they will usually tell ya if needed.
Understand the 5 to 1 thrust to weight ratio for lifting rocket off pad.[ 10 to 1 for breeze over 10-12 mph]
What glues to use for materials chosen in build.
How to design recovery components...sizing chutes and correct length of shock cords.
Attaching recovery harness to airframe/motor/motor mount [Y-harness]
Protecting recovery gear from scortch/burning. nomex, doc barf, piston, etc.

Choosing/adjusting delay in motors for correct apogee ..VERY IMPORTANT>>>>MAYBE EVEN MOST. You want that chute out at top, not early or late, would risk damage to chute or airframe. [no worries with fiberglass. lol]

Proper sturdy motor retention.
Using guidance...rail buttons or guides.
Understand motor choice and use for field conditions you may encounter. [peak thrust/average thrust/total lifting capabilities.]
The above are basics needed to build and fly a simple motor eject project for successful L-1 flights.

Then you can incorporate these below.

Advanced: when to upgrade fins/glues/body tubes for flying over mach.
using electronics for dual deploy.
Adding drogue for DD.
using trackers or GPS

AND MOST important have lots of fun and meet new friends along the way. Good luck!

low power kits will introduce you to the techniques involved in building hpr rockets.
Rex

Jim is absolutely right (as always). That's the way to gain your certs 1, 2, 3. I would suggest looking over the NAR level 2 exam and try to learn that stuff. Not needed until L2, but IMO it should be for L1. It's just basic rocketry that is as necessary for L1 as it is for L2 and beyond.

HOWEVER ... if you buy a kit that will fly equally well on G and H motors, and if you learn to fly it and recover it well on big G motors, there really isn't much difference in flying it on a baby H.

One warning: I have seen people (college aged, mostly) who come out to the field, launch their L1 cert flight with motor deployment, do everything right, get the main out at apogee, and watch it drift away, never to be seen again. YOU ABSOLUTELY NEED TO KNOW how to fly your field. Know the windspeed and direction, know your max altitude, know your descent rate, and know approximately where it is going to come down.

Before launching your cert flight, watch other people's. See where they are landing. If you don't think you can recover yours, don't launch it. There's always next month.

I did my level 1 on a 4" madcow super dx3 with an H100 motor and using motor deployment. It didn't go too high, i was able to see it the whole flight. Worked great for me.

Chad said:

I did my level 1 on a 4" madcow super dx3 with an H100 motor and using motor deployment. It didn't go too high, i was able to see it the whole flight. Worked great for me.

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How long did you spend flying LPR and MPR before feeling ready to go for L1?

JCRL said:

How long did you spend flying LPR and MPR before feeling ready to go for L1?

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Now you are on the right track. You can learn a lot about building and flying principles in LPR and MPR (and more economically). HPR lapel pins are not indicative of expertise.

Myself, I did LPR as a kid, and reintroduced myself to LPR and MPR for about 4 years as a BAR before thinking about L1.

It's really good that you are asking about this stuff!!!

Crazy Jim nailed it (as usual) but I might be able to add a few additional insights.

Move up the power-scale slowly, no need to rush. You will gain valuable insight with "G" motors. Smaller rockets might not seem as impressive as those M powered giants, but you can practice and learn almost every High Power technique with smaller, lighter less expensive "G" power. Perfect your building techniques, learn about motor assembly, Dual Deploy, Composite staging, recovery using RDF or GPS, and lots more. The altimeters and trackers you use in the "G" power rockets can be moved effortlessly to High Power when you are ready.

Make perfect and effortless recovery your main priority. The potential for disaster and financial loss increases greatly with the power increase. Use a checklist and do everything in your power to reduce the chance of ballistic recovery. Have a sure-fire plan to recover your rocket when it goes completely out of sight.

You'll get a ton of satisfaction when everything works exactly as you planned!


In This Photo:
Wildman Rocket $100. On-Board Electronics $150. High-Power rocket motor $200.
View from 2 miles high over Argonia Kansas - priceless!

I would get a mid power sized kit. LOC Vulcanite, Wildman Jr, something like that. pick something you like, and if your field size at your closest club is small, you may need to get something fatter to fly lower....but in general, get a nice, basic kit that's capable of flying on F and G motors... I'd recommend a 38 mount.

Then start a build thread here, and you'll get tons of specific advice

Buckeye said:

HPR lapel pins are not indicative of expertise.

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This.

@scsager that is one of the most beautiful pictures I've seen on this forum

I’m going to go counter to what many people say. If you have only built LPR before, I would strongly recommend building a heavy wall cardboard rocket with a 29mm motor mount and plywood fins. That will give you the building skills to build a rocket that will fly well on F and G motors in park flying mode. When you get comfortable with all of the skills Crazy Jim mentioned, then you can put in an H and get an L1. You’ll learn a lot in this build that you can take to a new HPR rocket with a 38mm mount that regularly flies on H and I motors.

So....what I did.....
My favorite rocket growing up was my Dad's Optima. So, I cloned it in blue tube.

2.6" wide, 4' tall. i used a 29mm mount. I've flown the snot out of this thing, but it flies well on an F50T, all the way up to an I200W. Love it. Built two more in blue tube, 38 mount and a dual 29. and a 2.2" downscale with a 38mm mount in carbon fiber. I have plans for a full scale fiberglass some day. (OK I have something like 12 or more optimas....but i digress)

My L1 was on this rocket with an H133BS, after several F and G flights. I don't think you need practice flights, and honestly they just add risk. But that's the way my path went. It's an easy size to fly, and durable.... I like it lots.

JCRL said:

@scsager that is one of the most beautiful pictures I've seen on this forum

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- Thanks!
This one was really a family project. My wife supplied her 2.6" Wildman Darkstar. I provided the K830 motor, and my daughter Sabrina supplied the cameras and project leadership. It was her idea to fly the biggest motor we could afford in a small/light rocket. Her goal was "Mach" + 2 to 3 miles high. Apogee was 11,500'. That photo is a screengrab from the onboard video. She got a few other good shots.

JCRL said:

How long did you spend flying LPR and MPR before feeling ready to go for L1?

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Thanks for starting this very interesting and useful thread. In my case, three years exactly (that was just coincidence). Unlike quite a few TRF'ers I didn't fly LPR as a kid. My journey in rocketry started when I built a few Estes kits stock, then got to know Open Rocket and started scratchbuilding. In the end my LPR stuff was reasonably sophisticated - ring fins, clusters etc. I watched HPR flyers at my club carefully, and learned about delays, prepping reloads etc. Before buying an HPR kit I talked to the vendor and a few L2 guys about suitable rockets for the field I was going to fly at. As a result of these discussions, my first HPR kit was a Loc Fantom: 4" dia airframe, 38mm MMT. Motor choice is in my signature - an CTI H125. Sometimes, because of the similarity of the materials people suggest Loc kits are just bigger versions of LPR, but at the time it felt like a challenge. Like others have suggested, I did a build thread here on TRF and I cannot thank everyone who chimed in enough.
And since we're posting nice-views-at-apogee pics, here's a recent one of mine deploying the drogue a tad under 8000' above Fairlie Moor in Scotland this summer, looking towards the Firth of Clyde and Great Cumbrae. In my head I can trace a direct geneology from this rocket (again, 4", mostly either Loc or PML materials) and that first HPR build I did 4 years ago:

JCRL said:

How long did you spend flying LPR and MPR before feeling ready to go for L1?

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growing up in Daytona Beach FL we saw a lot of shuttle launches and my father introduced me to model rockets. Now i have two kids of my own and one weekend decided to build/fly some models with them. They were not that interested but it really hooked me. I didn't fly any LPR or MPR before getting in to high-power. My first flight was an L1 attempt that failed (broken fin on landing). My second flight of the dx3 won me the L1 certification. However, I want to get into MPR in order to perfect some build ideas because high-power motors are so expensive.

Tim51 said:

Unlike quite a few TRF'ers I didn't fly LPR as a kid.

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I also never flew rockets as a kid. I think that I once built one in cub scouts, but I can't recall ever launching it. I caught the space bug a few years back, around the time that SpaceX started consistently landing their rockets. I had been kicking around the idea of building model rockets, but it felt like kid stuff, then I saw a profile on BP Space and his incredible landing rocket program in Nashville; a bought an Estes Viking within the week. So far I've just been flying on Bs and Cs at my local park with the Viking and an Estes Patriot.

JCRL said:

I also never flew rockets as a kid. I think that I once built one in cub scouts, but I can't recall ever launching it. I caught the space bug a few years back, around the time that SpaceX started consistently landing their rockets. I had been kicking around the idea of building model rockets, but it felt like kid stuff, then I saw a profile on BP Space and his incredible landing rocket program in Nashville; a bought an Estes Viking within the week. So far I've just been flying on Bs and Cs at my local park with the Viking and an Estes Patriot.

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you'll find this interesting too, developing a recovery chute that guides the rocket back to the pad after deployment

@Chad I just saw that video yesterday! I was hoping that it would have some information about how it worked; seemed really intriguing.

Not to gainsay or dispute anything posted so far, but:

JCRL said:

I understand that there are no hard and fast rules for this, but I'm curious if there is a generally accepted path to high power rocketry. What are the skills and fields of knowledge that you would want someone to attain before they consider going for L1 certification?

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Those are two distinct questions (the first doesn't have a lot to do with the second).

First question (overlong almost-an-answer):

L1 certification doesn't have to be too different from flying a big rocket on a mid power motor. Build and fly some mid power rockets before attempting L1.

I honestly have not seen a lot of fliers do it that way. Most of the L1 cert attempts I have seen seem to have been folks going straight from LPR to HPR, or folks who just started at HPR (who tried to cert at the first high power launch to which they brought a rocket).

If you want to scratch-build your L1 rocket, get Mike Westerfield's Make: High Power Rockets. (on Amazon here) for an expanded and illustrated version of the advice you got upthread -- all compiled into one place by one author who knows (pretty much) the subject about which he is writing. The L1 rocket presented in the book is a conventional design, does not require special tools or building techniques, and is made of easily sourced components (he includes a bill of materials for each of the rockets in the book).

If you want to build a kit, I'll echo @boatgeek: My advice would be to get something made from easily worked materials (paper and plywood) which will fly well on mid-power motors as and is capable of flying on an H. So a 29mm motor mount, or something that can easily be adapted down to 29mm.

My reasoning on this is that F and G motors are less expensive than H and I motors, and you can (probably) fly mid power in more places and under a greater range of conditions than you can fly high power -- so the rocket won't ONLY be your L1 rocket.

Really, for me, the trickiest parts turned out to be lining up the certifiers and arranging to have a another HP motor put aside for me in case I'd failed to certify on the first attempt (I brought two L1-capable rockets on the day I'd planned to fly for cert, in case the first attempt ended catastrophically. Since you are only permitted to buy one L1 motor prior to being certified I made arrangements with another flier to bring another copy of my cert motor to the field).

Flying a Jolly Logic chute release is not a terrible idea for a cert flight. It adds another potential point of failure, and puts one more thing to your checklist, but you will not certify if your rocket drifts away over the horizon.

Last thing I'd suggest: in addition to the certifiers try to line up a photographer/videographer to record the launch. It will be more fun for you to watch it happening if you don't have a camera in front of your face.

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As for what I would want to see someone do before getting certified... I'd include a written exam with some math problems. I'd ask questions like:

1) Why is it necessary for the CP to be aft of CG, and why is it desirable for it to be a at least one body diameter aft of CG.?

2) Why is the rule-of-thumb that it is better to launch on a motor with a thrust at least 5 times the pad-weight of the rocket, and what things might affect that determination (what circumstances could change that might incline you go with a lower thrust motor, or make it safer to go with a higher thrust motor)?

3) Why does the shock cord have to be as long as it is (and what can you do to get away with a shorter shock cord)?

4) When designing a rocket with a cluster of motors, why might it be safer to cant the engine mounts so that the nozzles are directed outwards from the central axis of the rocket?

... 5)... 6)... and a bunch more questions like this -- but these are only my opinions on the matter. You can certify (and fly happily for a long time) without knowing all of this stuff.

edit: Badly screwed up the bb code...

jlabrasca said:

Last thing I'd suggest: in addition to the certifiers try to line up a photographer/videographer to record the launch. It will be more fun for you to watch it happening if you don't have a camera in front of your face.

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Ditto that. You have two choices on launch day: 1) watch and pay attention to the flight, or 2) try to video it. It is pretty much impossible to do both.

All great advice above ^^

For those who don't have an interest in moving up the power curve slowly, be aware it is indeed possible, you just need to research and prepare more carefully.

Something mentioned obliquely - get to know your field and fellow fliers. You can't do HPR in a vacuum. You won't be park flying HPR like you mention with Bs and Cs.

Newly BAR'd, I was happy with mid-power. Estes PS11 kits (2-3", cardboard, 1/8" plywood). Scratch building upscales of my childhood favorites with 24-29mm mounts in BT70 and BT80. Club flying up to E-G. Orchard flying A-D. Not only are small motors less expensive, you will often hear the mantra 'know your field'. Knowing that wind x mph from which direction will put you in the trees, or in neighboring fields, or in the swamp.

Get to know the club members, get to know the field. The most important decision you may make in getting an L1 is to wait for better conditions.

My motivation to Level Up the first time was having to pull a rocket from the pad. I ran into a subtle difference in how the two local clubs regard lay people flying at club launches and F-G flights. On a day when I didn't have my boy (L1 Jr at the time) with me to just switch names. Oops. But the shame pushed me over the edge.

I did my L2 simply to spur my boy into finishing his. Competitive urge.

Charles_McG said:

I ran into a subtle difference in how the two local clubs regard lay people flying at club launches and F-G flights.

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What rule prevented you from flying mid-power as an uncertified flier?

Nytrunner said:

What rule prevented you from flying mid-power as an uncertified flier?

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Yeah, what's the rest of that story?

Nytrunner said:

What rule prevented you from flying mid-power as an uncertified flier?

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Don't know if this applies here, but our club got really squirrely about MPR, HPR, and non-certified people at HPR pads. Since one launch site (under FAR 101) had baby HPR and MPR on the same pads, everything got messy quickly. NAR and TRA safety codes have some moderately strict (and IMHO reasonable) limits on who can go to HPR pads.

Now that makes sense.

Good for a club to consider for their layouts (and challenging for clubs with limited equipment

If I understand correctly, TRA insurance doesn't cover non-members (except reciprocated NAR/BSA/etc.) at launches at all. The local club allows LPR fliers to fly with them anyway. The club defines LPR as A-E for this purpose.
If I understand correctly, NAR is much the same, but the local club keeps the normal LPR definition. Well, they use A-E for flight fees ($0).
For purposes of 'thriftiness', my Boyo was an NAR member, but I wasn't. We usually put rockets up under his name.
One TRA launch day, my Boyo had other fish to fry and I went alone. It was noticed after I had a G motor set up on the pad.
I didn't argue - I didn't intentionally trip over some fine print. I did fetch my launch fees back later.

And then I got an NAR membership of my own, and an L1 so it won't happen again.
Both clubs are full of fine folks, a number of whom are TRFers. If I didn't explain it exactly right, I'm at least close.

Makes more sense now.

At MDRA, we don't have separate HPR pads. My kids fly E motors on the 1010 rails right next to H, I and J motors. Wouldn't work at a NAR/TRA sanctioned launch.