It's kind of
rare that I am up before the crack of noon on Saturday.
But I somehow managed to crawl out of a warm bed into the frigid morning air - must have been in the low 60's!
Arrived at the sod farm about 9:30 and started getting the rocket together.
Fortunately, Dennis Welch of New
Horizons Hobbies was there with some badly needed DaveyFire ignitors.
I had cobbled together some ignitors which worked most of the time.
"Most of the time" is not good enough here. "Always" is preferred.
Here Greg Peebles kindly shows me how to pack the parachute. I haven't flown much HPR, and need every lesson I can get.
He even stayed cool when I accidentally fired both ejection charges. What a guy. But no damage was done, just the sweet smell of sulfur smoke lingering on me and probably him too... (Where ya been, honey? Out cavorting with Ms. Vesuvius again?) And it provided an inadvertent test of the ejection system: the main chute piston did not fully emerge. That led me to wonder, and finally realize that my finely-ground homebrew black powder is much lighter than the granular commercial stuff. So the volumetric measure that came with my CPR altimeter is not accurate here. It may throw a gram of FFFG, but it only throws 0.6 gram of my powder. So I doubled it up for the next round.
And now I know to pack the parachutes first, THEN load the altimeter. Duh.
Don't get excited... I am not aiming my Stinger at the passing trucks. Just yearning to hear those 3 little beeps that mean so much, checking the ignitors for continuity.
Chutes and ejection seem OK, so... ITS MOTOR TIME!
Since the loads were pre-assembled and dry-fitted as per Jeff Taylor's suggestion, it all went together smoothly at the launch site.
NEFAR Club prez Greg Lukach kindly called in for a window, as I suspect
this will go over the 2000 feet standing waiver.
Here is why:
Input to RocCAD:
No wonder sugar makes kids bounce off walls.
Mee too. I even supplement mine with caffeine to create a cup of artificial enthusiasm
Remember the old ads we saw on TV that proclaimed: "Sugar is all energy!"
In a sense that is true. Everything is all energy. Einstein fingered that one out. Clever guy.
But back to the launch. Here I am spreading Viagra on the launch rod. Or did they say Vaseline?
Funny thing. I finally learned how to block all the x-rated ads from my e-mail. Soon as I did so, started getting tons of ads for Viagra. Guess they figured that if I didn't want the former, I must need the latter. Those clever adver-teasers!
Do I look nervous? Well I am. Not used to launching in front
of a bunch of people.
I am confident of the motor. It will go. But where? Stability? Gonna trust PML on that one. Altimeter? Never used one before. E-matches? I trust them. I fired one as a test, and it had enthusiasm. I fired two more by accident while getting the airframe ready, and they worked fine. Really fine. I would be proud to make ignitors like that, and just might one day. Who owns Daveyfire? I want to buy some stock.
So I relax a minute and look at the scenery. Teresa took this one. She is getting pretty good.
Click on the picture above to get a "brief" (2 meg file, 7 seconds) video of the launch, including a few seconds of looking at the sky. It's up there somewhere! Comments from the crowd did my heart good. That alone made it worth all the work.
Click here for a longer video (8 meg .mpg file, 30 seconds of video) of the launch and recovery. My apologies to modem users.
Eventually it did come down, about 450 yards away. Farther than
expected for a "close proximity recovery" system.
But I am most relieved. It flew well and survived to fly again.
Teresa takes it easy while I do all the hard work...
...of listening to the altimeter beeping out its song.
Then a flash: My camera can record movies. The movies include sound. I will take a movie of the beeping, extract the audio, display it with GoldWave and capture the graphic with Paint Shop. Geek stuff 101.
Here it is:
So it went 4 beeps, 8 beeps, 4 beeps, and another 4 beeps = 4844 feet. A bit higher than expected. I am not the least bit disappointed, but do wonder about the difference. I also wonder about the accuracy of this kind of altimeter. No doubt there is some error, but how much? Maybe I should read the manual again.
Reassembled airframe and myself for streamlined travel, it's back to the truck for another round.
Loading is virtually identical to the first flight. Motor contains
about 5g less propellant, and is slightly slower-burning.
These differences are thought to be trivial.
Click the picture above for a video of this launch (813k
.mpg file, 4 seconds of video)
Click here for a video of its recovery (1.3 meg .mpg file, 15 seconds of video)
Returned to earth about as far away as the first launch. One of
the club members suggests that it is deploying the main parachute at apogee.
I suspect this is true.
Altimeter beeps: 4626 feet, almost exactly what the calcs predicted.
Again it is recovered intact and quickly readied for a third launch. Time is marching on...
The boys at the pad were comparing this propellant with APCP. Someone commented that it seemed just as powerful. While I would certainly like to believe that, I am also striving to practice good egonomics and avoid such tempting delusions. It is decidedly less powerful.
Comparing this with an APCP motor of similar size may provide a good illustration. For instance, the Animal Motor Works CC-54-1050 is also a 3-grain 54mm reload containing 598 grams of Green Gorilla, which I presume to be an AP composite propellant, with perhaps some barium nitrate or carbonate to give it a green color. It is designated a J-370, so its average thrust will be a bit lower, but it burns 2.7 seconds, roughly twice as long as my sugar grains. All told, Green Gorilla will deliver about half again as much impulse, and the calcs suggest it would send my little airframe to 7900 feet. Even further out of sight.
So if I am going for a space shot, creating surface-to-air missiles, or entering a high performance competition, APCP is the right stuff. Since I am not doing any of those at the moment, KN/SU will suffice.
Strong thrust, short burn. That's pretty much the KN/SU story. Clever grain configurations might allow a longer burn. KN/sorbitol burns more slowly. I think KN/SU propellant might be especially good for a first-stage booster, especially with an uninhibited grain with its gonzo thrust and regressive burn.
Or perhaps it would serve as an initiator grain for a hybrid motor -
use a grain large enough to kick the rocket off the pad, burn through the
tubing holding the NOX back, and ignite the PVC grain at the same time.
Maybe one could eliminate the high-voltage electrical ignition and make
it more reliable. "Tribrid" is taken, so what do you think... would
this be a "bibrid?" "dibrid?" (Aaaah! Somebody stop me!)
The sky is clearing and the wind is picking up. I have made an adjustment that might get the altimeter working in dual-deployment mode - I had left out one of the o-rings on the first two shots. But I cocked the launch rod into the wind a bit anyway...
Click the picture above for a video of this launch (1 meg .mpg file, 5 seconds of video)
A fellow rocketeer commented: "Hard to see a blue rocket against a blue sky..." He was right. It just vanished. That was pretty cool the first time, somewhat cool the second time but now it is getting old. When you stand around wondering where it is, and realizing that it went pretty much overhead. Still not real confident in the ejection system, I'm wondering if it will come down like it went up. I'll have to work on a smoke trail or something. Heard a "pop" from somewhere up there and started to breathe again. Much higher altitude and I might turn blue myself.
There was no video of the recovery, as this vehicle was lost from sight
in the clear blue sky. So here are a few earlier pictures of the
sky. Appropriate use of imagination is suggested.
But a couple of folks saw the rocket coming down in the distance, and pointed me in the general direction. So Teresa and I took off at a lope and combed the fields to and fro, back and forth, over again. As the sun was sinking low, I ran back to the truck, packed up our stuff real quick, learned that I had gone to the wrong spot, and headed back to where Teresa was still looking. Greg Peebles and Richard Creamer joined us to look. Greg pointed out the vicinity of where he had seen it coming down. I had misunderstood, and was combing the wrong field, of course. Richard carried his son Casey on his shoulders, over the fields looking too. Richard found it, way over in the cow pasture. Or maybe it was Casey who had a higher vantage point. By the time I got there Teresa had retrieved it, the altimeter still beeping its plaintive song: 4640 feet.
Apparently this altimeter's idea of dual deployment is to fire both parachutes at apogee. Unless I have done something wrong, which seems very likely.
Next time I launch this airframe it will be shocking pink or some other
obnoxious color so I can SEE it.
My truck could use the rest of that sky-colored paint.
Teresa rests after her vigorous walk.
So do I, a tired old guy.
So the Sudden Rush lives to fly another day. The Loki motor performed admirably every time. Recrystallized KN/SU can indeed power a rocket to substantial altitude, and quickly.
Possible changes for the next time:
- Add a smoke grain to aid in tracking. It will cut into the propellant supply somewhat, but the difference can be minimized. Perhaps by adding that conical grain-end mentioned above. And it really doesn't need to go that high. Two grains this size could produce 440 Ns thrust, sending it to about 2500 feet. That way I would have a chance to observe the entire flight and mebbe figure out if both ejection charges fired at apogee or did the inertia of the drogue deployment jar the nose cone loose? Expiring minds want to know!
- Lengthen the airframe by adding a payload section. Rocks, sand, beer cans, or non-vertebrate animals can be added as ballast to keep the altitude reasonable.
- Add roll or two of flourescent marking tape to the recovery tackle. 100 yards of dayglow streamer should make it easier to find among the cow-patties.
- Figure out why the dual-deployment system isn't working. That would make some of the other changes unnecessary.
- Fly it with sugar syrup propellant.
I suspect the sugar syrup version is inferior to recrystallized propellant,
but need to test that notion. It is much easier to make, and I believe
it can use fertilizer-grade KNO3, producing propellant for less than $1.
per pound. Economy is NOT a good reason to go into experimental rocketry,
but I gladly accept it as a side benefit.
Well that was fun! My deepest thanks to the officers and members of NEFAR who have encouraged me over the last couple of years since I have joined. This intrepid group of rugged individualists have provided all kinds of moral, technical, and administrative support to make this launch possible. And to Jeff Taylor for supplying such a fine motor casing, to Public Missiles for making good kits so I don't have to scratch-build everything at once, and to Dixie Crystals, for supplying the finest sucrose in convenient 5-pound bags.
Thanks guys! May there be many more!
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