[NRV Rocketry] How To Get into High Power Rockets
tweeks
tweeks at rackspace.com
Fri Aug 30 12:21:27 CDT 2013
Great tips Charles! Thanks for sharing!
Yes.. I know it's a lot of info. It will eventually get into our wiki that I'm
(still) setting up so that folks can edit and amend it. (want to help? :)
The L1 rocket list I linked to listed all decent MP-L1 kits, and I too included a link to
"Modern High-Power Rocketry 2". Good book. :)
Other experienced Rocketeers here have some "getting started in high power" tips?
How about some of our members who have got their L1 or L2 cert in 2013 like Charles?
Jimmy? Carlos? others? :)
As Charles and I said.. the /best/ (and cheapest) way to learn this stuff is to ask
questions of folks who have gone before.
Learn from others pain. Check it out some of our painful lessons from 2011-2013:
http://nrvr.org/photos/pics/canted_m.JPG
http://nrvr.org/photos/pics/burned-ring_m.JPG
http://nrvr.org/pics/big-bertha-crash.jpg
http://nrvr.org/photos/2013-04-13_VT-Kentland+Night-Launch/2013-04-13_vt-kentland_night-launch/img_7433_c.jpeg.html
http://nrvr.org/photos/2013-02-16_VT-Kentland-WEB/2013-02-16_vt-kentland/img_6398.jpeg.html
http://nrvr.org/photos/2013-02-16_VT-Kentland-WEB/2013-02-16_vt-kentland/img_6494.jpeg.html
http://nrvr.org/photos/2011-04_NRVR/2011-04_nrvr/dscf5748_flv.jpeg.html
Wow...
We really need to start a "Misery of Defeat/Really Cool Lessons Learned" page!
:vD
Not mocking folks pain (much ;), the point is here that each person involved
in the shots above can tell you exactly what NOT to do to avoid these costly
mistakes. ;)
As Monta likes to say,
"From the ashes of disaster grow the roses of success!"
-- Chitty Chitty Bang Bang
We invite you all to plant your roses in our garden!
It's a vast, fertile wasteland of knowledge. hehe.. ;)
Tweeks
NRVR Founder
On Friday 30 August 2013, Charles Albright wrote:
> Thank you, Tom , for your effort to provide a comprehensive picture of
> what's involved in the building and flying of high power rockets. There is
> much good information there.
>
> I'm concerned, however, that someone new to high power will find all that
> information hard to swallow in one gulp. I hope I can help simplify some
> of it and pare down the list to that which applies to one's first high
> power rocket.
>
> First, I highly recommend that you start by building your first high power
> rocket from a kit. This will provide you with hands-on experience with a
> well designed (stable) rocket and allow you to learn new building
> techniques without having to worry about acquiring all the right parts on
> your own. However, while the kit may provide a parachute, it may not
> provide a (Nomex or Kevlar) parachute protector. You should purchase and
> use such a protector. You may also have to provide your own motor
> retention hardware. And some high power kits will come with launch lugs,
> which may work just fine. But if you prefer rail buttons (as I do), you'll
> have to supply your own.
>
> There are a number of high power rocket kit manufacturers. As just one
> example, take a look at LOC Precision to see some of what's available.
>
> http://locprecision.com/
>
> You may want to start with a smaller "large" rocket kit designed to fly on
> a G motor as a way to ease your way into all this. Such a rocket will
> probably be somewhat like a scaled-up "Estes" rocket with some high power
> attributes. A G motor is the most powerful one you can buy without
> certification.
>
> For your first pure high power rocket, I recommend one with a 4" diameter
> body tube. Sometimes construction requires reaching down into the body
> tube to attach or glue (i.e. epoxy) a part and, in my experience, it can
> be very difficult to put your hand in a smaller tube and still be able to
> see what you're doing. And speaking of epoxy, in general the slower the
> cure, the stronger the bond. I use 30-minute epoxy most of the time, both
> because of the stronger bond and due to its more forgiving nature in that
> it allows you more time to get the glued part into its proper position
> before the epoxy "seizes" it. This can be especially important when
> inserting and fastening the motor mount to the inside of the booster body
> tube.
>
> Concerning materials, I recommend you stay away from fiberglass in the
> beginning. It can be messy and even dangerous, requiring breathing
> protection while cutting, drilling, and sanding it (think surgical masks).
> It is completely feasible to complete both Level 1 and Level 2
> certifications without ever touching fiberglass. I know because I've done
> it using only cardboard-type tubing.
>
> Concerning electronics, Level 1 certification can easily be achieved
> without any electronics, using only motor ejection to deploy a single
> parachute. More advanced techniques such as altimeter-controlled recovery,
> dual-deploy parachutes (drogue and main), shear pins, etc., can be left
> for higher certifications.
>
> I recommend using rocket design and simulation software to verify the
> performance of any high power rocket. One excellent example is the
> OpenRocket program which is available via free Internet download (no need
> to pay over $100 for Rocksim).
>
> http://openrocket.sourceforge.net/
>
> Such software can help you get the ejection timing right (i.e. at slow
> speed near apogee), which along with a long shock cord, is the best way to
> "zipper-proof" your rocket (i.e. avoid having the shock cord rip a slot
> down the side of the rocket body tube). Generally, zippering occurs
> because of bad recovery deployment design and timing, not because of a
> weak body tube.
>
> Finally, look at rockets successfully flown by others, ask for advice (from
> more than one person), and read and learn using the Tripoli and NAR
> websites and the excellent book by Mark Canepa, "Modern High-Power
> Rocketry 2." There is one copy available in the local public library
> system (on the shelf in Christiansburg).
>
> Charley Albright
> Tripoli # 14063, Level 2
>
>
> ----- Original Message -----
> From: "Thomas Weeks" <tweeksjunk2 at theweeks.org>
> To: <nrvr at nrvr.org>
> Sent: Friday, August 30, 2013 1:46 AM
> Subject: [NRV Rocketry] How To Get into High Power Rockets
>
>
> Someone at the meeting the other night asked me,
> "Tweeks.. how do I 'graduate' from fun little model rockets to
> these big ones that I've seen fly at some of these local NRVR launches?"
>
> What's the Same, and What's Different for High Power?
> ============================================================
> For those who are wanting to move to, or even just dabble in High Power
> rocketry, here are some of the most common differences between model
> rockets (A, B, C, D motors), medium power (E, F and G motors) and bigger
> beefier High Power (generally, H, I and up motors):
>
> Some construction and flight principals stay the same as low power/model
> rocketry: -What makes a rocket stable
> -Center of Gravity in front of Center of Pressure by 1.5 Body tube
> diameters (remember the string, "spin test"?)
> -You need a 5:1 thrust(N) to weight(N) ratio
> or weight of rocket(lbs) x 4.45(N/lb) x 5 ~ or < avg thrust of motor
> (N) Ex: 1lb rocket needs at least 22.25 Newtons of thrust motor, something
> like an F23 or bigger
>
> http://www.apogeerockets.com/Rocket_Motors/AeroTech_Motors/29mm_Motors_Sin
> gle_Use -Undistracted attention to packing your own chute
> (feels to tight.. do it again)
>
>
> The biggest differences between model/low-power and what you need to do for
> high power rockets construction and design wise are:
> -Higher speed flight = MUCH more violent component stresses
> -More stresses = Design Changes: "Beef-Up" everything
> -Move from glue to epoxy
> -beef up motor mount/bulkhead strength
> -move from elastic shock cords to nylon/kevlar shock cord
> -move from 2ft shock cord to 20ft shock cord
> -move from chute snap swivels to 1/4" quick links
> -zipper proofing your design or body tube
> -reinforce body tube strength (fiberglass/kevlar/carbon fiber)
> -reinforce fin root edge/mounting strength (through tube mounting)
> -use BEEFY fin fillets (epoxy, metal putty epoxy, etc)
> -high speed = greater internal pressure = popped nosecones = make vent
> holes -for chute protection move from paper wadding to kevlar cute cover
> -move from launch lugs to rail buttons
> -If in doubt, over design (to a point :)
> -Bigger rockets = more weight (more violent launches & ejections)
> -More weight requires slower/safer recoveries = larger chutes
> -Larger Chutes = more drift and...
> -need for smaller drogue chutes (more toward L2) to slow them down first
> -need for altimeter controlled drogue & main chutes ejections
> -need for Ebay/electronics and static port holes
> -need for secondary/backup ejection systems
> -ground ejection system testing
> -Higher speed/altitude/mass = MUCH more violent ejections
> -need for nosecone sheer pins to hold main chute in until needed
> -Preflight check list(s) (due to added ejection system complexities)
> -Compare notes, ask questions, learn from the experts (end THEIR mistakes
> ;)
>
> Also.. this is a great illustrated book to much of what I list above and
> more: "Modern High-Power Rocketry 2", by Mark Canepa
> http://www.amazon.com/dp/1412058104
> (we just gave a copy away at the last meeting!)
>
>
> What High Power Certification Is, And What's Required:
> ========================================================
> To even purchase these high power motors though requires a certification.
> So that's one reason why people even bother getting certified.
> You want to fly big rockets?
> You need to get certified (which is the industries way of keeping
> everything safe).
>
> Here is some info on what certification actually means:
> https://en.wikipedia.org/wiki/High-power_rocketry#Certification_in_the_USA_
> .26_Canada
>
> This means that you'll first need to either become a formal member of
> either NAR or TRA (Tripoli):
> http://www.tripoli.org/Certifications/tabid/80/Default.aspx
> http://www.nar.org/NARjoin.html
>
> NRVR is currently a TRA group(#143), but we can certify NAR members also,
> and the certifications are cross group compatible.
>
> You very first HP motor purchase is allowed, but you'll want to contact our
> group's RSO (rso at nrvr dot org) to go over your rocket, the motor you
> want, and announce that you desire to do a certification launch attempt.
> At this point, you do not have to be a member of NRVR, VAST, or any other
> local "club", but this is where most people go ahead and do join, as we
> will be helping you a lot during your journey to becoming certified.
> Here's how to join NRV Rocketry (our local club in the NRV):
> http://nrvr.org/membership/
>
>
> Get Your Level-1 Cert with a Rocket That Can Fly Both Medium & High Power:
> ===========================================================================
> === I always recommend that folks in the NRV start off with a dual purpose
> rocket that can fly as either medium power (F-G) or high power (H, I etc).
> Especially since some of our launches are medium and model rocket flights
> only, while only some (at this point) allow for high power flights. Here
> are several good Rockets to choose from, many of which can handle both
> medium power (F & G) as well as starter High Power (H) motors:
> http://www.apogeerockets.com/Rocket_Kits/Level_1_Certification_Kits
>
> NOTE: Personally, I recommend getting one with a 38mm motor mount.
> Cessaroni motors are the easiest (and cleanest) to work with. And they
> have a deal right now. If you're buying a "cert motor refill", the y give
> you the metal motor casing (a $40-50 value) for free! Just mention it when
> buying your Cessaroni motor refill grains. :)
>
> Also. here are a few really nice little videos (from Apogee) on the
> ins and outs of "Level-1" HP rocketry and certification:
>
> Intro to Level 1 Certification Rockets
> http://www.apogeerockets.com/Advanced_Construction_Videos/Rocketry_Video_60
>
>
> and then if you really want to see what building a Level-1 Rocket is like
> from start to finish, here's a really nice ten part video series on how to
> construct high power rockets, from beginning to end:
>
>
> Building Your First High Power Rocket - Part 1
> http://www.apogeerockets.com/Advanced_Construction_Videos/Rocketry_Video_61
>
>
> these videos above make for a really of useful set of starter videos to
> help those interested in moving a bit beyond the basic Estes model rockets
> of our childhood.
>
> Any other certified members have anything similar to share? Suggestions?
> Gotchas? Lessons Learned?
>
> Tweeks
> NRV Rocketry Founder
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