Build Thread: The Stars are Right... Mondo Kraken.

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Thanks, Layne!

Despite the kvetching, I am enjoying seeing this progress!

Status:

Nosecone: Filled, primed, sanded. Needs 2nd coat, and then will need masked off for canards to be painted. Seam lines still visible after sanding--denial technique may be required after final coat.
Upper AF: Filled, primed, sanded. First coat applied. Will sand and apply 2nd coat. Shear pins calculated, not yet drilled.
Av-Bay: Complete.
Lower AF: Masked, filled, primed x2. Waiting on second primer coat to cure, see if there's anymore filling to be done, or if I can live with the results as-is.
Fin #1: Masked, filled, primed x2. As lower AF.
Fin #2: Masked, filled, primed, sanded. Ready for second primer coat --minor blemishes.
Fin #3: Masked, filled. Ready for primer.
Fin #4: rejected. Waiting on replacement tube to re-cut, re-glass, and, obviously, finish.
MMT: Cut to length. CRs sanded to fit. Not yet installed (will do so after fins are on: need this out to properly clamp fins in place).
Retainer: Not yet installed.
Main chute: not yet purchased. Will be FC Iris Ultra 96" Target landing speed ~15 FPS.


Later!

--Coop
 
Have you decided on how the motor mount is going to be secured? I was always a little worried because there aren't any fin tabs preventing the motor mount and centering rings from just pushing through the rocket and out the front.
 
Have you decided on how the motor mount is going to be secured? I was always a little worried because there aren't any fin tabs preventing the motor mount and centering rings from just pushing through the rocket and out the front.

Epoxy?

It doesn't take much to have tremendous shear capacity.
 
Thanks for the question--while a tube fun such as this has no TTW tabs to lock the fins, AF, and MMT into one assembly, I am not worried about pushing the MMT through the airframe. The front and rear CR are double-thick, and there is a middle CR as well. Aeropoxy and generous foreward fillets will tie the CRs to the AF and MMT. I'm confident in its ability to hold...





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Two more replacement fins cut. One currently curing.

Shot nosecone, upper airframe, and lower airframe with first coat of paint.

Fins (except the one currently under construction) are in primer.

Starting to resemble something--pics soon!



Later!

--Coop
 
001.jpg

The fin I screwed up. Undig.

002.jpg

Yeah. It's bad.


IMG_0021.jpg

With luck...

IMG_0029.jpg
Maybe this one will be passable...


IMG_0031.jpg

...fingers crossed!

IMG_0020.jpg

...and starting the paint process...



Later!

--Coop
 
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Much thanks, Adrian! I'm pretty stoked about it. Looking forward to Red Glare this year, I'm telling you!


Later!

--Coop
 
Flight Report
Red Glare 17
MDRA
Higg's Farm.
250 Ell Downes Road
Henderson, MD.
April 12, 2015.


Weather: Sunny. Mid 60's. Slight breezes. Comfortable humidity.


Red Glare 17 was held April 10-12. Scheduling and financial concerns permitted only a day trip for us this time out, and Sunday, the 12th, proved to be the better day. And it couldn't have been more perfect. Field conditions were excellent. Rain in the mid-week left the dirt soft, but not muddy. You could drive on the property without concern of getting stuck.

We arrived around 1030. Flights were already well underway, and things were in full-swing by the time we unpacked the car. With me were my son and daughter, and my girlfriend's son, ages 12, 8, and 8.

12-year-old would be a junior L2, if he was a smidge older. He assists well in flight preparation of the larger rockets and had even designed a couple of them –one of which is an Estes Hornet upscale, to 4” diameter. It is dual-deploy with electronics on-board, and flies well on large I's and small J's. We have flown it on an I-350 with an adapter from 38mm up to 54, and on 54mm J-250s--the latter of which we have loaded for today.

My daughter gets real excited, and once she launches what she really wanted to, she gets equally excited about chasing ladybugs and playing with any other kid in the general vicinity. She will also just sit and watch any motor J or better. Tell her an N sparky is about to go, and you'll have her full attention. What she REALLY wanted to fly today is a tiny rocket on a little itsy bitsy motor (½ A) because she can do it all herself. While she has large rockets (some much larger), she doesn’t like that daddy has to do the motors or set up the electronics. She feels Daddy's job should be to help fold parachutes and fill out flight cards.

My girlfriend's son has been to launches with us before, little ones in the park when he was real young (and didn't like the noise), but also a large club launch, so he's seen it before. He has not, however, flown anything before –we're correcting that this time. He is the proud owner of a small Estes easy-to-build kit, and we picked up a few B6-4 motors for him at the Animal Motor Works trailer. He's attentive when being shown how to do something, and seems to be analyzing everything that's going on.

Personally, I had three main projects I wanted to fly. All were Pemberton Technologies designs. First, was the Screamin' Green Meanie kit. I'd launched this before on C-11's and D-12's often, but it has sat for a year or two status-post rebuild and upgrade: the original cardboard centering rings had blown out, making for a loose-fitting motor mount. These had been replaced with light ply rings and a screw-on retainer. The heavier components in the back necessitated additional nose weight up front for stability. Thus, the entire rocket is heavier enough so that C-11's are out completely, and it might hit 150 feet on a D-12 3. Problem there (aside from “why bother?” altitude) is that everything else we have that flies on D's takes D-12 5's. The 5-second delay on this, at that altitude, would lead to a crash. So we need something with more power. I've got a couple of Cesaroni 2-grain F motors, and wanted to fly this on the F-51, which should give it a nice, high flight to about a thousand feet. Unfortunately, this flight didn't occur, despite being all set up for it. Had we another day, then yes. But I ran out of time and daylight.

Similarly, my daughter's G-force's flight was scrubbed. This was on-deck, however, problems with getting Devon's Hornet off the pad put us three flights down. We kept having igniter problems with it, and after three tries, that flight was scrubbed because I'd feared the altimeter battery might be getting low on power, and I didn't want to put it up in the air with a questionable battery, perhaps leading to a ballistic recovery (major safety concern) and there was just no time to disassemble and replace it, even if we got a known good ignition source (I left my multimeter at home in order to save space).

So those three planned flights didn't happen.

The ones that did:

My girlfriend's son flew his rocket on a B-6-4. It was a textbook flight, however, during recovery, the small, substandard shock cord attachment point the manufacturer needlessly insists on molding into their plastic broke, and it landed in two pieces. It is easily fixed, and something I'd considered modifying right from gitgo, however, I didn't, because I didn't have the tools at her house when I walked him through the build. This failure is completely my fault. But other than the broken mount, no damage, and so I consider this a successful flight on his record to 475 feet. The Lunch Control Officer (LCO) let the five hundred or so people in attendance that this was his first flight ever, and he did get a round of applause.

My son flew his Pem-tech Kraken three times on D-12's to ~650 feet, each. Each one was flawless. This is a fantastic motor and rocket combination. And it looks so damned cool doing it! Maybe next time, I get him a couple of single-use E's, just to see what he does with them...

After the thrice-failed Hornet, I brought forth the King Kraken. This is a Pemberton kit, and when I built it, I knew this was going to be my penultimate level one kit. If I could get that thing up in the air and recover it damage-free, I would consider myself ready for a Level 2 attempt. Today's flight was on an I-180-9 –a motor choice that gave Mr. Pemberton himself pause –he cautioned about a long walk to recover. Well, he was fairly on-point. With the parachute ejecting at apogee, barely visible at roughly 2400 feet up, it took a while to get back to earth, riding the 30” Fruity Chutes parachute and a leisurely 15 feet per second. However, the winds were kind, and we could see where it landed from the flight line. My son recovered it while I was getting the big project on the pad. We kept in touch by cell phone throughout the recovery.

The big project was next: Mondo Kraken. Mondo Kraken has been my pet project for a long time. It was originally conceived in 2012. I began fiddling with the design file on the 18th of March, 2013. I finished fiddling and called it “good to begin” a year later, on the 28th of March, 2014. Construction began 1st of April of the same year and was completed on June 25th. Moving to a new home, schedules, and money delayed the first flight until now.

An overview: Mondo Kraken is a 2.0x upscale of the King Kraken in length, but 1.78x upscale in width. She is 5.54” in diameter, with fiberglass reinforcement to the airframe as well as the interior and exterior aspects of the signature tube fins (and yes, glassing the interior aspects of those fins was a complete bitch). She stands 7 feet tall, and weighs 12Kg empty. A kilogram of lead in the nose keeps her at around 3 calibers of stability. However, this places the nosecone and assorted bits and pieces at 2,500 grams itself.

She has two altimeter circuits: a Missile Works RRC3 and she was scheduled to fly a Telemetrum, however, problems with the Telemetrum led to a last-minute replacement to a Missile Works RRC2+, a simple reporting altimeter, which doens't permit downloading flight data, merely beeps out max altitude. The RRC3, however, does permit downloading the data, albeit not as much data as the Telemetrum, had it been functional, would have yielded. The RRC2+ is perfect in its simplicity, and after a slight modififcation to the av-bay, was installed 3 days prior to flight. The Telemetrum, once functional, will be able to be reinstalled with ease.

Recovery logic is to deploy a drogue chute at apogee, which I estimated to be at 3,100 feet. 3 grams of black powder would shear the 4 #4-40 pins holding the pieces together, separate the airframe, and deploy the drogue. The backup altimeter (RRC2+) would fire another 3 gram charge 1 second after apogee. With the upper airframe tethered to the lower by 50' of 9/16” tubular kevlar, this would fall at roughly 75 feet per second to 800 feet, where the RRC2+ would fire its main charge. The RRC3 would fire a backup to the main at 700 feet. Each main charge is 4 grams of black powder. At this point, the charge shears off the 4 pins holding the nosecone on, and a 48” parachute deploys. This does not recover the rocket, however; it is attached to the nosecone, and a deployment bag. When the 48” inflates, it pulls the deployment bag off of the main chute: a 96” diameter black and purple beauty by Fruity Chutes custom-ordered for this project in matching colors. Under main, and without the extra weight of the heavy nosecone, the rocket descends at 14-15 feet per second until landing. The nosecone rides the 48” chute at roughly 16 feet per second. Complicated? Yes. And with complicated comes nerve-wracking.

Also to add to my stress level, the motor: Mondo Kraken has a 75mm (3-inch) motor. I'd never assembled a motor this large, and though I'd read the instructions several times, and had seen a video online of a similar motor (same hardware, different reload kit with different assembly requirements), I'd never done one myself, and just wanted someone with a clue to be there for some guidance. Robert DeHate was, thankfully, on-scene with Animal Motor Works, and was gracious enough to assist and explain things so that next time, I think I'd be good to go. My inexperience was, honestly, the biggest time-killer this trip. For the next time out, I think we will do better.

With the altimeters checked and re-checked, motor assembled, dog barf added, ejection charges made, shear pins installed, and flight card filled out, I brought the thing to the RSO table. With the motor in, and everything, she was flirting with 16Kg. I found my way to the C rack, and a 1515 rail that was a little shorter than I found ideal, but I figured what's two feet among friends? I positioned the rail for loading and realized my helper was a thousand yards away, getting King Kraken out of the field in which it had landed. Damnit.

Thankfully, the flier next to me (whose name I completely forget, and I apologize for that) took pity on my dumb ass and gave me a hand getting Mondo onto the rail and raised up to position. I armed the altimeters, activated the cameras, and installed the igniter –heeding Robert DeHate's advice on proper seating depth for motors of this size. The previously-mentioned flier whose name I forget despite his kindness even took the obligatory “guy standing next to his rocket on the pad” photo for me with my phone. This will only be shown to close friends and not published online, as my likeness need never be committed to any website.

What seemed like an eternity later, they announced my flight. Luck had positioned my tent so that I had a clear view of my rocket on the pad. I stood as close as the safety barriers permitted, and began recording video on my phone. My son took pictures with his.

When the LCO hit the button, I held my breath, and the motor puked out a gout of flame. This was silent, orange-yellow, and smokeless. That vision lasted only a fraction of a second, because in the next eighth-second, that motor came up to pressure. When it did, it was as if the gates of Hell had been thrown open, and all the demons within were spitting and screaming with rage. There was a reverse mushroom cloud of smoke and sparks that completely obscured the rocket next to mine on the pad. The Mondo Kraken was released. As she began to climb, the flame from the motor kept growing. As long as the rocket... twice as long... THREE times as long... 20+ feet of flame growling out the back of that thing as she nosed right into the sky. The published burn time on that motor is 3.8 seconds, but that has to be an error... it seemed MUCH MUCH longer. Finally, it burned out, and we watched the tracking smoke trail grow as she kept rising. She reached apogee, and I could see a small plume of white smoke WAY up there... I knew we had an event, and after a few seconds, I could see it falling under drogue through the binoculars. It flopped around on the air currents as it descended, however, mostly lay flat, with the upper airframe slightly higher than the lower, thanks to the parachute attached close to its aft end. After a minute or so of descent, which, again, seemed like thirty, I said to the kids: “We should be seeing the main soon.” As I uttered this, I could see another smoke plume and heard the report of the charge firing. The nosecone came off, the red and blue 48” inflated, and then, in glorious splendor, the black and purple 96” blossomed, and the rocket swung underneath the main canopy. The nosecone and 48” chute drifted close by, like a planet orbiting its parent star. It came to rest 500 yards or so away, and I could see where it had landed.

The kids were clamoring for me to come on and go get it.

I lit an Oliva Serie G, and started walking.
 
Congratulations! That was a spectacular flight. But the memories with the kids... Priceless.

What motor was that? I apologize if I missed it. The plume on that was phenomenal!
 
Thanks, Bill!

It was a CTI L-820.


Later!

--Coop
 
I did not get the camera angles I wanted. The rearward-facing camera cut out prior to launch (operator error), and the sideline video we tried taking came out all blurry. The keychain cam I had slapped on with electrical tape, however, did work, and we got some interesting footage from it.

[video]https://youtu.be/-l3VdfDc80c[/video]

Later!

--Coop
 
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