Level-3 high-performance design and build thread

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Before the launch:
IMG_3103.jpg

IMG_3104.jpg

After: (That's just the wind picking up the chute)
IMG_3106.jpg

IMG_3108.jpg

IMG_3109.jpg

IMG_3119.jpg


The blank oval is from the Darrell Mobley sticker that ablated away on the way up. Otherwise, the fins were undamaged.

More pics and a video in a bit. Raven data file is attached. You can read it by downloading the Featherweight Interface Program at
https://www.featherweightaltimeters.com/FIP.php

View attachment L3L Oct9 2011.FIPa
 
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such a beautiful rocket!!!

i was about to post about a pre/post flight picture, and then you post it 2 mintues before i ask!

can't wait to see the custom nose cone in L3 ready position. What altitude did the telemetrum and beeline read out?
 
[YOUTUBE]rWI29JmCtWk[/YOUTUBE]

As usual with the NCR club, I had a lot of help today. It started immediately after I arrived, when I realized that I left my big plastic bin of tools and supplies at home, 2 hours behind me. But I did have my computer and tracking equipment with me, and the rocket was pretty much complete. But who would ever have a socket wrench with an 8" extension? Mike Shinn did, along with the case and hardware he lent to me. Anyone have grease and a warm place to prep the motor? (It was drizzlinig, windy, and 35 degrees earlier this morning) Larry Haynes did with his RV, along with coffee and donuts. Help with assembling my first 3 inch motor? Steve Jensen was there.. Oh, my shear pin material (1/16" basswood) is in that bin too. No worries. Dave Bishop has some 2/56 nylon screws, and a tap and drill. And sandpaper for the final pre-launch finish. Chris LaPanse and Vic helped set up the tower. Bdale and Keith Packard de-conflicted the Telemetrum channels. Bear helped pack up. Joe Hinton does all the million things needed to put on a smooth launch and also coordinated my FAA high-altitude call-in window, provided a nice motor cleaning station (Chlorox wipes work great) and reminded me to fill out the record application paperwork. And so on. I'm probably leaving someone out, but suffice to say it was a team effort today to work around my packing screw-up and get the flight off. Overall it was just a great day today. And congrats to Dave Hanson on his level-3, and the CAP for their cool red-blue-white flight, among other notable flights.

More flight details: I wound up with a very large stability margin (6+ inches), which made me feel more confident about the fact that I had a couple of fins that were a little tweaked. But I was still pretty nervous about having a clean boost. Extra stability margin really covers well for a lot of errors, because the boost appeared to be nice and clean. I angled the tower 2 degrees away from the flight line, and a little toward the south, since there was about a 10 mph wind from the North. But since it was only about a 15 G boost, it weathercocked a bit toward the North and a little West.

I had a Telemetrum coverage the whole way, though when it was most distant there wasn't a lot of margin for error with my Yagi pointing. The new Telemetrum interface with the az and el helped there. But boy, I would sure like an option for crummy American units. We saw the max altitude on the display, and I was worried for a minute that 9745 meters might have broken the 35,000 waiver. And some sort of error in a quick calculation gave us an initial altitude of 32,000 something, which was announced before we caught the error.

Kudos to RASAero for again nailing the altitude prediction. I bet if I put in the 10 mph launch wind, rather than the 6 mph launch wind, that it will be right on.

The rocket landed on private property just N of the Pawnee National Grasslands, 2.1 miles from the pads, but I had the number of the landowner programmed in my cell phone and I got permission to retrieve the rocket as I drove out to get close to it. As soon as I got over the last rise, I could see the big orange chute ballooning up. Getting sight of an intact rocket on the ground is my favorite part of rocketry, (though kicking back with a beer and a laptop looking at data after a flight is a close second). The rocket was doing its best to get back home, and went a hundred yards or so while I was watching it.

Damage report:

Nosecone: I had some blistering, mostly near the tip, but in some spots along the side. Just some raised welts.
Airframe tube: No damage.
Fins: No damage at all. The post-cured Aeropoxy really worked well, and I didn't see any ablation or any change to the surface. It still had some wipe marks from when I put on the last coat of epoxy. The Darrell Mobley sticker did come off, as expected.
Shock cord: none
Chute: Maybe a few scorches. I haven't done a close inspection yet, though.

From this afternoon's quick look at the Raven data, it looks like the deployments were benign, the descent rate pre-chute was 150 feet/second, and 19 feet/second after main deployment. The main chute took quite a while to inflate, losing about 500 feet between initiation and full inflation. The accelerometer was significantly off, based on the accel-based apogee time. I didn't re-calibrate the accel during my pre-launch checkout, and it looks like I should have. I think it might have been 10%+ low, but even so, it was reading about 1400 mph, Mach 1.8. I think the real top speed was around Mach 2, due to the motor burn being longer than expected, at about 5.2 seconds.
 
Adrian, your post demonstrates beautifully what is so great about this hobby - the willingess of people to support and help each other.
 
Adrian A said:
...but I guess beauty is in the eye of the beholder.
Click to expand...

As Henry Ford said, "The most beautiful things in the world are those from which all excess
weight has been removed."

Congrats on a spectacular flight!
 
Beautiful flight yesterday Adrian, and I'm glad I was there to see it (and help out where I could).
 
Congrats on an amazing *test* flight! Beautiful project and awesomely aggressive build nature!

Will the M configuration rocket be the same length?

Great job!!!

-Eric-
 
dhurstell said:
A sure precursor to disaster in any of my projects.... :y:

Whats your secret for avoiding such obvious jinx?!?!!!
Click to expand...

Sledgehammer testing for the chute holder and stand-on-the-tube testing for the fins. :gavel:

ECayemberg said:
Congrats on an amazing *test* flight! Beautiful project and awesomely aggressive build nature!

Will the M configuration rocket be the same length?

Great job!!!

-Eric-
Click to expand...

Thanks, guys. What I flew was a 4-grain case, and I'm planning to fly at least a 6-grain case for my level-3 cert flight. I'll leave the aft tube extra long so that in case a manufacturer comes out with a bigger 75mm motor, I can use that.

Since the rocket will be significantly longer, I'll redesign the fins to take advantage of that. I'm not sure yet if I will go with a clipped delta shape or the swept-back fins like I had on the L3L version I just flew. I'm not worried about the swept back landing durability any longer, especially since my new big chute brought this down at only 19 feet/second.

Thinking about my strategy for motor selection I still like the idea of flying the L3 cert with a motor that I'm very confident the rocket can handle, and moderately confident it will set a new M record. Then I'll fly it with an extension sleeve in front of the aft tube with the highest-simming certified motor that's available for the flight. The extension sleeve wouldn't take any real loads, and it would just be there for aerodynamic continuity. I could glue it in and fair it in between flights.
 
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Adrian, great design and flight. Very impressive. I noticed there looks to be more friction-fit tape showing on the motor casing in the landing photo compared to the pre-launch photo. Did the booster section actually shift relative to the casing/av-bay at some point or am I missing something? I'm assuming the case heat made the tape adhesive gooey and the apogee event shock kicked the case a little bit?
 
TD Sky said:
Adrian, great design and flight. Very impressive. I noticed there looks to be more friction-fit tape showing on the motor casing in the landing photo compared to the pre-launch photo. Did the booster section actually shift relative to the casing/av-bay at some point or am I missing something? I'm assuming the case heat made the tape adhesive gooey and the apogee event shock kicked the case a little bit?
Click to expand...

The motor is really the central structure in the rocket. The aft airframe tube with the fins is captured on the bottom by the thrust ring, but it can slide upwards. I did a friction fit with the blue tape just to keep it from bouncing around too much after the apogee deployment. The tape came off fine with no residue. Blue tape is an essential part of all my rockets. Here it worked great for keeping the shock cord from snagging on the inside of the nosecone, it held down the Beeline GPS antenna and some wire inside the av-bay, and it was used for the aft fin can friction fit.
 
Burner said:
Adrian,

Are you using the same nosecone for the M flights?
Click to expand...

I'm going to work with Jeff Lane (Shockwave rocketry) on a new version of the cone with high-temperature resin and anything else we can think of to improve the heat resistance. My goal is to have it come back from the cert flight without any damage, and then fly it again the next day in an all-out flight and have it stay together.
 
bandman444 said:
What is the red piece at the top of the tower? Seems built for the design.

Bryce
Click to expand...

That's just the top of the tower that I built and painted about 3 years ago. It's just 3 2x3's with 1/4" plywood triangles screwed and glued to hold them together. I used 3/8" hooks that were threaded into 3/8" rod couplers that were potted into the 2x3s. For this flight I was nervous about fin clearance, so I used a belt sander to carve out some more clearance from the plywood triangles. The fins add a 4" radius to the 3" tube (11" total), and the tower can accommodate that with about 3/4" of margin as long as the rocket stays within about +/20 degrees of roll on the way up. More than that and the fins would run into the 2x3's.
 
Good news: Greg was able to download the Beeline GPS flight data, and it looks good, with a good lock before apogee. Initial report is 31,600 feet. I'll dig into the KML file and plot it against the Raven for an interesting comparison.

LrecordGoogleEarth.jpg


Edit: I tried to upload the kml file directly, but that's not one of the allowed file types.
 
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Here's the KML data converted to altitude vs. time and plotted against the Raven data:

L3LGPScomparisonplot.gif


The pad altitude from the GPS is pretty fuzzy, so I adjusted it to put zero at the altitude readout just before liftoff. That also allows the low-altitude portion at the end of the flight to match the Raven data pretty well, also.
 
Here's some food for thought. Data on the SR-71 Blackbird suggests that at cruise speed, roughly mach 2.5 to mach 3, the canopy glass INSIDE temps were over 600 degrees F.

One caveat, though, the SR-71 was at cruise speeds for much longer than any of our rockets are capable of.
 
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