Armed Polite Society
Main Forums => The Roundtable => Topic started by: RocketMan on August 23, 2009, 11:54:23 PM
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For any interested folks in the Pacific Northwest, OregonRocketry will be holding a rocket launch near Sheridan, Oregon, the weekend of Sept. 12-13.
All classes of rockets will be flown, from the small model rockets all the way up to high power sport rockets on 'J' and 'K' motors. There may be a sprinkling of heavier rockets on 'L' and 'M' motors, as well.
It is open to the public, and the public may fly their rockets for a small daily launch fee, $10 per day, or $15 for the weekend.
See the OregonRocketry (http://www.oregonrocketry.com/index.htm) website for details and maps to the Sheridan launch site.
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A little too far away, I think.
I recently got back into model rockets when my grandson visited and I built a few Estes rockets because it is something he really enjoys (me too). Among others, I built a Stormcaster, a particularly handsome rocket.
Right now I'm building an Apogee Aspire. This is a $20 rocket that, with the right F-motor, will exceed 1 mile in altitude. With the right G-motor, will exceed the speed of sound (800 to 900 MPH).
Of course, I also took him shooting at a local range, another activity he really enjoys. It was his first time shooting a 9mm (my Beretta 92FS). He was a bit intimidated at first (he usually shoots .22 at the range), but I gradually coaxed him into it, and after his first shot it was blam-blam-blam-blam ... =D
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That sounds pretty cool. I'm gonna try and keep that open in my calender. Might be pretty cool for the kiddo.
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That sounds pretty cool. I'm gonna try and keep that open in my calender. Might be pretty cool for the kiddo.
I'm planning on Saturday, myself. If you decide to go that day, follow me up. I know a short cut. =D
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In the September 2009 issue of Popular Mechanics, page 81, there is a photo and description of a 1:10 scale model of a Saturn V rocket some guy in Ohio built. It is 36 feet tall, weighs 1648 pounds, and flew 4441 feet in altitude on eight N-Class motors and one P-Class motor. :cool:
Some people just have way too much free time. :lol:
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...I also took him shooting at a local range, another activity he really enjoys. It was his first time shooting a 9mm (my Beretta 92FS). He was a bit intimidated at first (he usually shoots .22 at the range), but I gradually coaxed him into it, and after his first shot it was blam-blam-blam-blam ... =D
Sounds like he's thoroughly hooked. :)
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In the September 2009 issue of Popular Mechanics, page 81, there is a photo and description of a 1:10 scale model of a Saturn V rocket some guy in Ohio built. It is 36 feet tall, weighs 1648 pounds, and flew 4441 feet in altitude on eight N-Class motors and one P-Class motor. :cool:
Some people just have way too much free time. :lol:
This guy (http://www.rocketryplanet.com/content/view/2829/38/)
Flight is here (http://www.youtube.com/watch?v=bj4lj6YSwzg)
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:O :O :O
That's incredible ! Even landed upright, ready to launch again. =D
Never mind about the Popular Mechanics article ... :lol:
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This guy (http://www.rocketryplanet.com/content/view/2829/38/)
Flight is here (http://www.youtube.com/watch?v=bj4lj6YSwzg)
I love the cars driving past in the background, you can just imagine the reaction when that thing went off.
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:O :O :O
That's incredible ! Even landed upright, ready to launch again. =D
That was pretty slick, wasn't it?
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I wonder if the builder is considering riding in it himself ? It is clearly big enough for him to fit inside, and it already weighs 1600 lbs, so his body weight would only add another 10%. Probably less risky than Evel Knievel's launch across the canyon, assuming he could handle the 7 Gs of acceleration.
But I wouldn't want to try it.
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I love the cars driving past in the background, you can just imagine the reaction when that thing went off.
Maybe the builder can design the next one to look like an ICBM. =D
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It is open to the public, and the public may fly their rockets for a small daily launch fee, $10 per day, or $15 for the weekend.
I keep meaning to get out and try my FlisKits Corona with the booster, but without the booster on a B6 I nearly lost it last time. I need a day when it's either truly dead calm or a very gentle wind along the long direction of our land. Even on a pair of Bs the lateral travel expected in a 5mph wind is a few hundred yards.
I've also got a 24mm I've been building as an oversized camera payloader loosely based on the Corona, but after i got it far enough along to figure the actual weight, I found that nothing less than a D12 will get it off the pad fast enough to be stable, (and that to barely enough altitude to call it "flight") even with the lightest camera/battery/storage setup I've seen. I'll probably hold off finishing it until I get around to ordering a 24mm reloadable setup for more punch.
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Not familiar with the Corona, but if it uses a parachute for recovery can you use a smaller chute or a streamer ? I assume if you're using a B6 that it is a fairly light rocket.
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Estes makes a single-use black powder 24mm 'E' motor. Would that have enough kick to get your camera rocket off the pad fast enough to be stable KD5NRH?
Or, use a longer launch rod, so the rocket is going faster when it leaves the rod.
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Maybe the builder can design the next one to look like an ICBM. =D
I am sure most people can't recognize brands of ICBMs on site and wouldn't know the difference - nor do they know precisely what size an ICBM should be. They's just see a HUEG ROCKET taking off and be reasonably freaked out.
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Mrs. AD and I are planning on being there on Saturday.... Should be a lot of fun. I may have to bring out my rockets to play... :)
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I wonder if the builder is considering riding in it himself ?
That is a serious no-can-do in the model rocketry realm. Technically, you cannot fly any living creature. It is a violation of both the NAR and Tripoli safety codes. (Except maybe, you could fly fistful. =D)
That said, someone, somewhere, will probably fly in his own rocket someday, safety regs be danged. :)
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That is a serious no-can-do in the model rocketry realm.
Wouldn't that just be the point where you'd drop "model" from model rocketry? =)
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Wouldn't that just be the point where you'd drop "model" from model rocketry?
It actually brings it into another area of FAA regulations, outside of the part of FAR101 that governs model and amateur rocketry. I imagine there are a lot of other .gov regulations that come into play, as well. Not a simple undertaking.
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That sounded AWESOME. :O
Also, if anyone was seriously interested, look here: http://www.faa.gov/about/office_org/headquarters_offices/ast/licenses_permits/
Don't ask why I had that page bookmarked. :angel:
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Not familiar with the Corona, but if it uses a parachute for recovery can you use a smaller chute or a streamer ? I assume if you're using a B6 that it is a fairly light rocket.
Light, but a tad delicate:
http://www.fliskits.com/products/rocketkits/kit_detail/corona.htm
Mine on the pad:
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Fkd5nrh.smugmug.com%2Fphotos%2F541245807_nbosZ-M-1.jpg&hash=ac01e46717b22209d52f8a28d03c6bae71178fc2)
It came down pretty hard with the original chute with a slightly oversized cutout. If I could be sure it would end up in the grass, I could probably let it land a bit faster, but there are a lot of hard-packed spots that the rockets seem to aim for.
Estes makes a single-use black powder 24mm 'E' motor. Would that have enough kick to get your camera rocket off the pad fast enough to be stable KD5NRH?
Or, use a longer launch rod, so the rocket is going faster when it leaves the rod.
It might. IIRC, my calculations assumed going up to a 6ft rod rather than the 3ft I've been using. Rail lugs wouldn't work for this one, since the lower launch lug will have to be inside the fin ring, but not directly against the rocket's body, so that the upper one can be on the payload section.
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I am sure most people can't recognize brands of ICBMs on site and wouldn't know the difference - nor do they know precisely what size an ICBM should be. They's just see a HUEG ROCKET taking off and be reasonably freaked out.
I'm sure you're right. However, I was punctuating the humorous insight advanced by Mr. Cola more than making a serious suggestion.
I suppose if we really want to impress (terrify) the uninitiated, we could write "ICBM" in large letters on the side. Of course, the viewers pretty much have to read it before it launches. :laugh:
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Or, use a longer launch rod, so the rocket is going faster when it leaves the rod.
Why would that increase the velocity ? That works with a firearm, because a longer barrel means the expanding gases are pushing (accelerating) the bullet for a longer time before it leaves the barrel, but the longer rod doesn't result in the motor pushing for a longer duration. The only advantage I see of the longer rod is increased stability (and THAT would increase speed a bit, I suppose) and greater directional control as it leaves the launch pad. I would think the longer rod would result in more friction.
I'm probably wrong, but here's my chance to learn why. =)
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That said, someone, somewhere, will probably fly in his own rocket someday, safety regs be danged. :)
No kidding. Besides the safety risk, why on earth wouldn't you?
As far as risk goes, people fly ultralights and hang gliders and such all the time. A well-designed rocket can't be much more dangerous than that.
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ultra lights don't go near as fast. and i've seen some stuff go very bad off the launch rod
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ultra lights don't go near as fast. and i've seen some stuff go very bad off the launch rod
People do dangerous things. Some people knowingly do dangerous things.
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Why would that increase the velocity ?
I worded that poorly, Silver Bullet. My fault. It is a matter of propulsive force (engine thrust) exerted over time.
(For example's sake only, I'm pulling the following numbers out of thin air. A rocket's acceleration and eventual velocity are highly dependant on a number of factors too messy to include here.)
A rocket constantly accelerates as long as its engine burns. And for the most part, the faster the rocket is moving, the better the guidance effect of the fins.
With its motor burning, a rocket will be moving at x velocity when it reaches the end of a 3 foot launch rod. At that speed the fins may or may not have enough air moving over them to provide for stable flight when the rocket leaves the rod.
A rocket using a six foot launch rod will have had more time to accelerate to a higher velocity when it reaches the end of the rod, and the air moving over the fins will of course be moving faster, providing a greater flight control effect.
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(Except maybe, you could fly fistful. =D)
Hey now. Just because NASA put monkeys in orbit, doesn't mean you can do it, too.
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A rocket constantly accelerates as long as its engine burns. And for the most part, the faster the rocket is moving, the better the guidance effect of the fins.
With its motor burning, a rocket will be moving at x velocity when it reaches the end of a 3 foot launch rod. At that speed the fins may or may not have enough air moving over them to provide for stable flight when the rocket leaves the rod.
A rocket using a six foot launch rod will have had more time to accelerate to a higher velocity when it reaches the end of the rod, and the air moving over the fins will of course be moving faster, providing a greater flight control effect.
I had to read that twice. =)
A rocket at six feet will be going at the same speed regardless of whether the rod was 3 feet or 6 feet. v = v(0) + at. But, you're stating that on the six foot rod the rocket will be under greater aerodynamic "control" and thus is more stable at 6 ft + . In fact, at 3 ft + . The part that is new to me is "At that speed the fins may or may not have enough air moving over them to provide for stable flight" . I didn't realize there is a discontinuity, or nonlinearity, in the dynamic. I guess I just figured it was as simple as keeping the center of pressure behind the center of gravity, and you're saying (I think) that might not be enough; that the velocity has to be above a certain minimum for that stabilizing factor to work. Interesting.
In any case, if I have any rocketry questions, I'll know who to ask. :cool:
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I had to read that twice. =)
A rocket at six feet will be going at the same speed regardless of whether the rod was 3 feet or 6 feet. v = v(0) + at. But, you're stating that on the six foot rod the rocket will be under greater aerodynamic "control" and thus is more stable at 6 ft + . In fact, at 3 ft + . The part that is new to me is "At that speed the fins may or may not have enough air moving over them to provide for stable flight" . I didn't realize there is a discontinuity, or nonlinearity, in the dynamic. I guess I just figured it was as simple as keeping the center of pressure behind the center of gravity, and you're saying (I think) that might not be enough; that the velocity has to be above a certain minimum for that stabilizing factor to work. Interesting.
In any case, if I have any rocketry questions, I'll know who to ask. :cool:
Friction and air resistance... don't forget about them...
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So much for writing that late at night. You still had to read it twice. :laugh:
SB, you are correct in that the CP must remain behind the CG for the rocket to maintain stable flight. Swap those two and the rocket turns into a sky writer or a lawn dart.
The rule of thumb for that separation is one caliber, i.e., one diameter of the rocket body. One caliber being a hard minimum, but up to two calibers is done sometimes. Beyond two calibers, and stability problems can start to creep in again.
For the fins to exert flight corrective "pressure" at the CP, air must be moving over them. To exert enough pressure for stable flight, the air must be moving over the fins a minimum velocity. That minimum varies from rocket to rocket, depending on a whole host of design parameters.
To simplify things for the rocket flyer, a "rule of thumb" is once again used, that being 30 mph. The rocket should be moving at a minimum of 30 mph as it leaves the launch rod to maintain stability.
Many of us rocketeers use computer programs to design and flight model our rockets. I use one called RockSim by an outfit out of Colorado Springs.
Dionysusigma, air drag, gravity, even the friction of the launch rod and launch lug, are the complexities that I was ignoring for simplicity's sake.
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Why would that increase the velocity ? That works with a firearm, because a longer barrel means the expanding gases are pushing (accelerating) the bullet for a longer time before it leaves the barrel, but the longer rod doesn't result in the motor pushing for a longer duration. The only advantage I see of the longer rod is increased stability (and THAT would increase speed a bit, I suppose) and greater directional control as it leaves the launch pad. I would think the longer rod would result in more friction.
I'm probably wrong, but here's my chance to learn why. =)
It's not that the rocket would be going faster at the end of the motor burn. It's that it would be traveling faster when it left the rod. The acceleration the rocket experiences is not instant, and in fact is not a constant either. So a longer rod means that the rocket is being stabilized by the rod for a longer amount of time, which means that the rocket is traveling faster when it leaves the stability of the rod.
EDIT: Whoops, shoulda noticed the "page 2" button... But you're right in that at 6feet above the ground, the rocket is traveling at the same velocity regardless of the length of the launch rod. The difference is, with a 6 foot rod, the rocket is still being stabilized waiting to reach that critical stable velocity.
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SB, you are correct in that the CP must remain behind the CG for the rocket to maintain stable flight. Swap those two and the rocket turns into a sky writer or a lawn dart.
http://www.youtube.com/watch?v=QD8Sx4v-aXw
This is what happens when you don't hit that critical stable velocity. A longer launch rod would probably have helped on this one. Instead, since one of the fins broke off on impact, I just ended up redesigning the fins a little larger to move the CP further to the rear.
Here's the successful launch: http://www.youtube.com/watch?v=Os7Sik7Gxmc (sorry about the sideways view. forgot that I didn't have the software to rotate the video).
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A longer launch rod would probably have helped on this one.
Shorter delay too; it's supposed to pop immediately after it hits the ground :lol:
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THIS is one of my favorite model rocket videos:
http://www.youtube.com/watch?v=oqt3y19N9AI
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The rule of thumb for that separation is one caliber, i.e., one diameter of the rocket body.
...
Many of us rocketeers use computer programs to design and flight model our rockets. I use one called RockSim by an outfit out of Colorado Springs.
Over two calibers of separation leads to stability problems ? I guess my Rocketry 101 education I got from the Estes catalog decades ago (1. Get the CP behind the CG and you’re good to go. 2. Move the CP back by building bigger fins. 3. Move the CG forward by using a longer tube) is good for a first order approximation, but nowhere near the whole story.
Can’t get away from RockSim. I don’t have it, but some of the online rocket dealers are constantly waving it in my face. Given what you said about two calibers of separation between CP and CG, I can see why it would save a lot of trial and error when designing your own rockets.
One of my rockets came with CP and CG decals. I know you can determine the CG by balancing the rocket on your finger and seeing where it levels. I was trying to figure how folks determined the CP location to place that decal. One approach that occurred to me was to gradually move the CG back using weights inside the rocket, and observe at what point the rocket became unstable. I now realize that they are more likely using a program such as RockSim to calculate the location. Cheaters. :laugh:
Swap those two and the rocket turns into a sky writer
“Not that there’s anything wrong with that”; sky writers are very entertaining! (See AmbulanceDriver’s link above).
Speaking of sky writers and lawn darts .. I assume everybody here has seen the movie October Sky, based on the book Rocket Boys? Wonderful movie.
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Over two calibers of separation leads to stability problems ? I guess my Rocketry 101 education I got from the Estes catalog decades ago (1. Get the CP behind the CG and you’re good to go. 2. Move the CP back by building bigger fins. 3. Move the CG forward by using a longer tube) is good for a first order approximation, but nowhere near the whole story.
Can’t get away from RockSim. I don’t have it, but some of the online rocket dealers are constantly waving it in my face. Given what you said about two calibers of separation between CP and CG, I can see why it would save a lot of trial and error when designing your own rockets.
One of my rockets came with CP and CG decals. I know you can determine the CG by balancing the rocket on your finger and seeing where it levels. I was trying to figure how folks determined the CP location to place that decal. One approach that occurred to me was to gradually move the CG back using weights inside the rocket, and observe at what point the rocket became unstable. I now realize that they are more likely using a program such as RockSim to calculate the location. Cheaters. :laugh:
“Not that there’s anything wrong with that”; sky writers are very entertaining! (See AmbulanceDriver’s link above).
Speaking of sky writers and lawn darts .. I assume everybody here has seen the movie October Sky, based on the book Rocket Boys? Wonderful movie.
SB, one of the ways I learned to approximate CP is to take a cardboard cutout of the profile of your rocket. The point at which your rocket cutout balances (the CG of the cutout) is the approximate CP.
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That sounds fairly crude. =)
How do you deal with the fins ? Make a silhouette of each and tape it at their location near the end of the tube ? That would seem proportional.
I suspect there are certain assumptions made with that approach, such as a nose cone with reasonably good ballistic coefficient. Otherwise, you could have a flat end (no nose cone) which wouldn't make much difference in your profile, but which would make a huge difference in the actual rocket (moving the CP to the front).
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How does someone "break into" model rocketry? This seems like something I'd love to do, but have never had the opportunity... =(
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Easiest way, for about $20, is to buy an Estes starter kit, IMO. It will come with a rocket, an engine, a launch pad, and a launch controller. Actually, everything you need to launch a rocket ... once.
http://www.estesrockets.com/categories.php?cat=starter
Lots of hobby stores carry these, and even some crafts stores like Michael's.
It's very easy at this level. Things to be aware of when buying a starter kit:
1) There are varying degrees of difficulty, ranging from rockets already completely built, to requiring very little effort (ETX, I think), to requiring a little more skill (Level 1, 2, 3).
Also, when you buy a kit, you will want to buy extra engines. Look on the starter kit package to see what engines the manufacturer recommends for the rocket. They usually come in packages of three. Two or three packages should be sufficient for your first time out. I usually get some in one of the lesser power sizes (like 'A' or 'B') and also one in a higher power ('C' or 'D'), depending on the recommended engines for that particular rocket.
I also always buy an extra package of igniters and an extra package of wadding.
You'll probably need some white or wood glue. I doubt you'll need paint unless you get a Level 1, 2, or 3 rocket. Actually, I think it's not so much skill as it is patience.
The thing about rockets is it can be a lot of fun for very little effort and money. Also, it's a very fun thing to do with kids.
I only get involved with it once every year or so, and then I put it aside for awhile. It is not satisfying on the level of shooting, but it's more relaxed, cheaper, easier, at least at this level. You can build bigger, more powerful rockets, and you can design your own. Both of those paths take more money (but not much) and involvement.
The starter kits make it pretty foolproof. Observe carefully the instructions regarding putting the igniters in the engines. Estes, I think, has a great page on their web site about igniters. But, even if you do it wrong, it'll still work half the time. It's easy to do right, and easy to do wrong if you don't read the instructions.
This is a hobby that scales up. The small rockets that use 'A' and 'B' engines cost about fifty cents per launch. It's hard to beat the cost with any other hobby. My 'D' engines cost me $5, I think ? They are for bigger rockets. The 'E' engines I bought for my Aspire cost me $11 each.
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Ummm, I guess my prices were a bit off. That was off the top of my head, and my head seems to get shorter every year ... =(
https://www.discountrocketry.com/model-rocket-engines-c-9_38.html?osCsid=6aed6d9eb9e81a40001dede3f36a0e8b (https://www.discountrocketry.com/model-rocket-engines-c-9_38.html?osCsid=6aed6d9eb9e81a40001dede3f36a0e8b)
This page is showing you prices for packages of THREE engines. So, divide each dollar amount by three to get the price per, plus shipping.
I try to support my local hobby shop, even though their prices on rockets are about 20% high, except when I'm buying something they don't have; then I shop online.
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This thread was nice to read. =)
I have been wanting to get back into rocketry for awhile. Once this grad school craziness is over, maybe I will. Rocksim looks pretty cool, I will have to try the 30 day trial. I think this is a nerdy enough endeavor to teach my future child.
It would be interesting to figure out a way to move the CM mid-flight. Combined with an accelerometer you could control the trajectory. I could do that in labview, at least in theory. I imagine actually doing it could be difficult though.
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You ought to come down to the Sheridan launch, Physics, even if it's just for a couple of hours. I think you'd enjoy it.
It would be interesting to figure out a way to move the CM mid-flight. Combined with an accelerometer you could control the trajectory.
Yes you could, but it is seriously frowned upon. Guided missle stuff there, and .gov gets all jittery about that. All model rockets must be free flight, no guidance at all.
That does not include rocket boosted gliders, however. Lots of folks doing scale R/C space shuttles and the like.
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Alas, I will be in the lab all day. You are right, I would love it, and as soon as grad school is done I can focus on hobbies again. I should be done with my masters in a couple of months and will be taking a year break to make money.
Yes you could, but it is seriously frowned upon. Guided missle stuff there, and .gov gets all jittery about that. All model rockets must be free flight, no guidance at all.
That does not include rocket boosted gliders, however. Lots of folks doing scale R/C space shuttles and the like.
I didn't realize there were regs on this type of stuff. Damn, I need someone to hire me so I can do this stuff I guess. :| Anyone got the hookup at Raytheon? ;)
See that bums me out. Every time I get an idea to do some fun physics experiment, it's always freaking illegal!* What the hell kind of commie country regulates perchloric acid anyways? =D =D Luckily they haven't regulated ball lightning yet. :cool:
*In case you were wondering, yes, that was a joke.
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Y'all have convinced me to get back into model rocketry for the edification of my children.
It has nothing to do with my own enjoyment of model rocketry as a child or that the first program I wrote in my first programming language* that had a physics component was a means to estimate how high my rocket would fly.
* Quick Basic, the worlds most worthless language
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/seriously wondering if it's possible to rig an RC sub to launch a rocket... =)
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/seriously wondering if it's possible to rig an RC sub to launch a rocket... =)
In my ill-spent youth, I rigged model rockets to fire into the water and they seemed to keep burning just fine.
Given that black powder has all the oxygen it needs in the mix, I think they would work fine if you could properly seal/insulate the engine & igniter hardware.
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/seriously wondering if it's possible to rig an RC sub to launch a rocket... =)
http://rcmodelsubmarines.co.uk/#/1100-ssbn-624-woodrow-wilson/4530491327 (http://rcmodelsubmarines.co.uk/#/1100-ssbn-624-woodrow-wilson/4530491327)
You just need to build a sealed tube for the rocket to go in! Maybe rig a CO2 cartridge to eject the missile rocket with a small delay before the engine ignites.
How is that gyroscope and micro-nuke research going? =D
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Here is a spring-launched tube with electrical torpedo for a RC sub:
http://www.youtube.com/watch?v=rbGdml7aB10&feature=related
Part one of four.
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This is what you need.... Just wait for about the 10 second mark.... :)
http://www.youtube.com/watch?v=B0nw7312VJs
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Yes you could, but it is seriously frowned upon. Guided missle stuff there, and .gov gets all jittery about that. All model rockets must be free flight, no guidance at all.
I wasn't interested until you said that. Is something wrong with me?
*rushes off to buy servos and a remote control*
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There is one type of "guidance" that is legal, or at least I have never heard of it being questioned by .gov. Some folks do it for the technical challenge involved. It is to build a rocket that is a sun-seeker. The guidance system causes the rocket to actively steer toward the sun. Of course, to keep the rocket flying close to vertical, you want to launch it when the sun is high in the sky.
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There is one type of "guidance" that is legal, or at least I have never heard of it being questioned by .gov. Some folks do it for the technical challenge involved. It is to build a rocket that is a sun-seeker. The guidance system causes the rocket to actively steer toward the sun. Of course, to keep the rocket flying close to vertical, you want to launch it when the sun is high in the sky.
So what you're really saying is they are trying to make an early model sidewinder? =D
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Rat bastards... =D
1 x Quest Big Betty Kit (QU-1014) = $9.09
1 x Quest Skyscope Altitude Measurer 2 Pack (QU-7812) = $4.89
2 x Quest Payloader One Kit (QU-1018) = $14.68
2 x Quest B6-4 Motors (QU-5741) = $12.16
2 x Quest A6-4 Motors (QU-5740) = $11.74
1 x Quest T-Minus 5 Two Rocket Starter Set (QU-5736) = $30.09
1 x Quest Q2G2 Igniters (QU-7024) = $4.89
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To further whet some appetites, try these:
A great general rocketry website with a good forum: Rocketry Planet (http://www.rocketryplanet.com)
A well known manufacturer of HPR motors and stuff: Aerotech (http://www.aerotech-rocketry.com)
Another good site. With links to other good sites, too: Fly Rockets! (http://www.flyrockets.com/index.asp)
Another rocketry forum (part of a vendor website): Ye Olde Rocket Forum (http://forums.rocketshoppe.com)
HPR motors by the subsidiary of a Canadian company that make motors for commercial
and military uses: Cesaroni Technology (http://www.pro38.com)
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Hey, AmbulanceDriver, you still planning on going to the launch Saturday? Fjolnirsson and I are getting our schedules dialed in. We'll be leaving the Lebanon area NLT 0900, expect to be at the launch site 1030-ish.
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Yeah, was just talking it over w/ the Mrs. It sounds like we'll be heading out there... Should we bring a canopy type thing for cover, or will there be stuff like that set up? Don't wanna get broiled.... Especially the Mrs. Also bringing chairs, lunch, and lotsa water. :)
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Bring your own canopy if you have one. I've got an old beat up unit that's been to a lot of launches. Not a pop-up, so I may just tough it out (with the hat that Balog sold me :) ).
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We've got a 10x10 canopy. We'll make sure to bring it. It's a pop-up, so it's pretty easy to set up.
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yeah, we have an old canopy, but again. not a pop up, so I doubt we'll bring it.
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We had a great time at the rocket launch Saturday. Fjolnirsson was not able to make it due to a sick kidlet. Hopefully she is doing better.
AmbulanceDriver made the launch. He managed some successful flights on an Estes rocket he brought along. I will let him weigh in on his experiences.
My #2 son and a couple of his friends attended. We finally got our rocket fix after being away from the hobby for four years. He flew two of his rockets multiple times on 'G' class motors, including his first attempt at using a reloadable motor. Aside from a bee sting, he had a great time.
I made just three flights, but they were all perfect. The first was a small Loc Precision "Aura" I've had for close to twenty years. It went up on a single-use Aerotech D30-4T for a good flight. It spit the motor and adapter at apogee, but that's no big deal. The adapter was cobbled together from 50¢ worth of parts from the junk box, so I am out nothing.
The second flight was a five foot tall, three inch diameter custom rocket I call "Lancer", on a single-use Aerotech G80-7W motor. Another perfect flight and recovery.
My last flight of the day was my custom Payloader III rocket. At about six feet tall, it went up on a high power Aerotech H148-R motor. It used motor delay charge ejection, not electronics, and yet it ejected the chute right at appogee. Dead on perfect.
It was a good day overall. I came home dead tired, sunburned, back aching, feet blistered, but as content as I could be.
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Sounds great !
I've got my eye on a Pemberton Kraken lately. Don't know if I'll take the plunge or not right now. I need to practice standing and sitting shooting prior to my next Appleseed, which is coming up fast.
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Might as well make my rocket report.
Last week the kiddos took out the Quest Astra III kit and launched it four times, more or less successfully. Also had four more or less successful landings.
Assembly of Quest Astra III
To start with, I put the rather simple rocket together the night before. It called for the gel model glue like one would use on plastic model planes. Well, I didn't have that, but I did have some old-school JB Weld. That seemed to work wherever glue was called for, uh-huh.
I like the way Quest has a kevlar cord connected to the motor mount up through the body tube and then it tied to an elastic cord connecting to the nose cone.
Another mod to the kit was to use a dab of wood glue on every knot, shock cord & parachute.
Last, I used a fishing barrel swivel & hook about 3" short of hte nose cone as my chute/streamer attachment.
Model Rocketry Pain in the ass Factor
Finding a place to shoot them off was much harder than expected. The city of Richardson bans them at all parks. Plano has just one place in one park where they can be shot from April-October...with a permit if you are 18+ years old. I managed to get a permit.
When I was a kid, any ol' park that looked big enough was good enough. Seems our hyper-regulated society is regulating such hobbies out of existence. I would have no place to shoot them in cycling distance, were I living at my address and 12YO.
The local rocketry organization, http://www.dars.org/, has a couple other spots that can be used year-round, but they are a good ways away. Like, 20 miles & 60 miles, roughly. DARS wants $15/year to launch rockets at these sites, but they can only be utilized during sanctioned launch dates & times. Also, they imply, per their membership app (http://www.dars.org/images/darsapp.pdf) that they expect you to be a member of a national org (http://www.nar.org/) or (http://www.tripoli.org) both of which cost $60+/year.
The PITA factor was something I did not reckon with, as I ordered the materials. I am mightily angry over it, to be frank.
Flight of Quest Astra III
I was able to talk my neighbor, the disabled (TBI) PhD EE who lives behind us, to come along. We have both done rocketry, but he has the distinction of being arrested by the city for shooting off rockets. So, along with my 4YO son and 3YO daughter, we went to the designated launch section of the designated park.
All shots were done with Quest A6-4 motors, the minimum suggested motor. The launch site is so small, I would be loathe to launch this rocket with a B motor and a chute. A streamer would be the way to go.
There was a slight breeze and I took that into account with my launch site. The first launch was my daughter's turn and it went up in a large arc. I think I used too much dog barf wadding and the chute did not open, but clumped together, despite the suggested chute fold.
The second launch was my boy's first, done with a rather long streamer made from yellow "Caution" tape. This sucker was WAY overloaded, despite the lesser amount of dog barf. It went up, cocked over and looked to power into the ground cone first when, 10-15' above ground, the recovery blast went off, decelerating it and disrupting its flight. The only damage done was a busted plastic fin.
I mended the fin with Krazy Glue gel, which did a smash-up job. I called a break and we got drinks & snacks as the Krazy Glue set.
Next flight, also set off by my boy, I cut off half the streamer and it went up pretty well, mostly stright...and came down pretty well. The fin held up to the impact. (Next time I use a streamer, I'll use the length of the original, but cut out half of it from the side with alternating slices.)
The last flightwas also set off by my boy. I used the chute, again, with minimal dog barf, and pushed it all down way toward the engine mount. It was the best flight & recovery, as it went up straight up and came straight down, as the chute deployed wonderfully.
Every launch we counted down from 5 and then yelled "Blast off!" and mashed to launch button. My daughter was scared of hte rocket launch and did not want to be that close after the first. Both hooted & hollered as the rockets went up and ran after them as they came down.
Everybody enjoyed the outing and I was impressed at how robust the starter rocket was.
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Many of our benighted city and county government types, along with the school boards of various locales, have seen fit, in their infinite wisdom, to ban rocketry activities. After all, someone might get killed with those dangerous toys. So say their lawyers, anyway.
Nevermind that not one person has ever been killed as a direct result of flying model rockets.
And nevermind the number of children that die each year across this country engaging in school sanctioned athletic events.
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I suspect that stability is more dependent upon the ratio of forward velocity/exhaust gas velocity than it is dependent upon velocity of air moving across the fins.
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I suspect that stability is more dependent upon the ratio of forward velocity/exhaust gas velocity than it is dependent upon velocity of air moving across the fins.
Nope. If that were the case, non-gyroscopically stabilized rockets would not need fins.
Air moving across the fins is the important factor. The fins are airfoils that provide corrective force to the body of the rocket. The point at which the fins apply that force is called the "Cp", or Center of Pressure. Stability is highly dependant on the Cp sitting behind the rocket's Center of Gravity, or Cg. It should be somewhere between one and two calibers behind the Cg. Less than one caliber behind the Cg and the rocket will not be stable.
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Aight. I have to weigh in here. Very nice to meet RocketMan and his son, and SWMBO and I had a great time. We were actually sitting back from the flight line about 30 feet or so, which made watching the launches a little easier on the necks. :)
Saw everything motor wise from 1/2A's in the little rockets all the way up to a massive K motor which caused a silght amount of alarm from the launch coordinators (apparently they were afraid there wasn't enough distance from the flight line to the launch pad in the event that K motor decided to spontaneously disassemble itself). But in the end they launched it. and boy did that sucker fly. Witnessed a couple of impressive failures.
One of the less impressive failures was my little rocket. Scratch built guy with a streamer recovery powered by those little (by comparison to some) D-size estes motors...
First launch was absolutely beautemous. Streamer popped just past apogee, and the whole shebang drifted gently down to earth. As I was reloading it for the second flight, I was examining my shock cord, as it looked a little frayed and dried out. Was thinking I really ought to replace it, but figured it was good for one more flight.....
Launched, apogee, and pop, there's the streamer. But it's looking a little funny. Hrm. Dang it. Shock cord didn't hold up. Nose cone and streamer are still attached. But the body tube is now in a beautiful ballistic trajectory. Impact was pretty hard. When they reopened the range, headed out there to recover it. Sure enough, the body tube had telescoped about 4 inches shorter than it had originally been. *sigh*
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Judging by his reaction at the high power launches, I think AmbulanceDriver will get hooked on the big stuff. Hopefully you've got good credit limits on your cards. =D
It was a real pleasure meeting you and yours on Saturday, AmbulanceDriver. I'm glad you enjoyed the day.
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Make sure to let us know about the next one! I want to go to one of these but am just so dang busy. =)
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Let there be photos!
My neighbor snapped some phonecam photos.
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Flh6.ggpht.com%2F_ifsRjdJE1Jg%2FSrGX020FZFI%2FAAAAAAAAANA%2Fh8mI-gkMWvY%2Fs800%2Frocket_eliz_2009-09-05_01.jpg&hash=e1ee3b91454419389af51483ae625efee106392d)
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Flh5.ggpht.com%2F_ifsRjdJE1Jg%2FSrGX1HgXcqI%2FAAAAAAAAANE%2FFQ6wTkA6hWg%2Fs800%2Frocket_jason_2009-09-05_01.jpg&hash=2fd3679fa9bfc530402d2593cb243dee5754206f)
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Flh6.ggpht.com%2F_ifsRjdJE1Jg%2FSrGX1MHsVGI%2FAAAAAAAAANI%2FoQPxPbpo174%2Fs800%2Frocket_jason_luke_2009-09-05_01.jpg&hash=36b00e03f07e99776b62b7777214633fc5f8a89c)
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Flh5.ggpht.com%2F_ifsRjdJE1Jg%2FSrGX1Fy30bI%2FAAAAAAAAANY%2F1Ju05zkQb-c%2Fs800%2Frocket_jason_luke_2009-09-05_02.jpg&hash=7e2b57e01761d0c2e43668d8e05f9b382a68bc43)
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Flh4.ggpht.com%2F_ifsRjdJE1Jg%2FSrGX1axJxSI%2FAAAAAAAAANQ%2FF-GYiERLw9c%2Fs800%2Frocket_jason_luke_eliz_2009-09-05_02.jpg&hash=30aa86a0edc0bee23c607fa77c8edccc16525be1)
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Flh5.ggpht.com%2F_ifsRjdJE1Jg%2FSrGX8NoDNHI%2FAAAAAAAAANU%2FTNFx5xB3OTA%2Fs800%2Frocket_luke_eliz_209-09-05_01.jpg&hash=982428ad22b24aaabb9ce75562aaf37841d75735)
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My son used his digital SLR to take (what I hope will turn out to be) some good photos of the launch. As soon as he sends them to me I will post the best ones.
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Pictures!
Rockets in the truck
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Fi480.photobucket.com%2Falbums%2Frr170%2Fswestby%2FDSC_0052-resized.jpg&hash=f17c9b956211d685f9fb4ced5243b7fcefa91aad)
The yellow and blue rocket is my custom built Lancer, going up on a G80-7W.
The red, black and gold rocket next to it is my son's custom built Apocalypse, going up on a G79-7 IIRC.
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Fi480.photobucket.com%2Falbums%2Frr170%2Fswestby%2FDSC_0067-resized.jpg&hash=02ccd6d0d1aaa495e043a178e31d595d510d44c9)
Here's my son Matt and I behind the pad discussing a problem with the launch ignition leads.
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Lancer on liftoff.
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Matt's custom Prometheus about to go up on the first reload he has ever put together,
a G64-7W. It snapped off the pad so fast, it made a loud CRACK...,
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Fi480.photobucket.com%2Falbums%2Frr170%2Fswestby%2FDSC_0180-resized.jpg&hash=32948a89998a3653c3c34d06d536b1948e4fcad9)
...and we only got a shot of the motor flame, that with the camera running at 3fps.
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Getting ready to load my Payloader III. It went up on an H148R-M, cut to about a 7 second delay.
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Payloader III on the pad.
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Payloader III liftoff.
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Fi480.photobucket.com%2Falbums%2Frr170%2Fswestby%2FDSC_0153-cropped.jpg&hash=39b7bc479c59cd67a10dc08b34c6d58e97b8922b)
Payloader III at ejection. If you look closely, you can see the smoke coming from just behind
the forward section of the rocket. The ejection occurred right at apogee. It doesn't get any
better than that for motor ejection with a manually trimmed delay charge, without using electronics.
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Fi480.photobucket.com%2Falbums%2Frr170%2Fswestby%2FDSC_0160-resized.jpg&hash=befe2b7e4c7db17ce533f3895ba890ef1a42ae52)
Payloader III under the laundry.
(https://armedpolitesociety.com/proxy.php?request=http%3A%2F%2Fi480.photobucket.com%2Falbums%2Frr170%2Fswestby%2FDSC_0172-resized.jpg&hash=3e4d772ba4a32513d4c0fac009342c6acb0db958)