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REV 2.4 - Sat Jun 25 15:49:47 2011

Door Knob
P.O. Box 470396
Broadview Heights OH 44147
(330) 745-9755
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SPECS: 62" x 7.67" - 130.7 oz
ROCKSIM FILE: Right Click to Download
SpaceCAD FILE: MISSING - please submit here
REC'D MOTORS: 54mm, H - K

(Contributed - by Michael Erwin - 10/29/09)

HPR, Parachute, Level2, 54mm MMT, Upgraded SkyAngle 60" Custom Classic II Chute.


Parts in the kit were:

  • 1 x 7.5" BT
  • 1 x 54mm MMT
  • 4 .x 25" Plywood Fins
  • 4 x Loc-N-Fin Fin holders
  • 1 x .25" MMT Forward Centering Ring with .25" hole drilled for Eye bolt
  • 1 x .25" MMT Rear Centering Ring
  • 1 x Eye Bolt
  • 2 x Washers
  • 1 x .25 Nut
  • 1 x Paper Launch Lug
  • 1 x 25' 9/16" Tubular Nylon Shock Cord with quality loops
  • 1 x .25 quick link rated at 800lbs
  • 1 x 60" LOC/Precision Chute upgrade at LOC to a SkyAngle 60" Custom Classic II

After seeing Barry Lynch of LOC/Precision flying a Doorknob at our local launch, I knew I wanted to this to be my Level 2 attempt kit.

Instructions while brief & to the point, they were logical and extremely easy to follow. Take your time and dry fit everything, including the LOC-N-FIN pieces. After using the LOC-N-FIN building method, I am already looking forward to additional LOC/Precision large kits.

While I used heavy duty epoxy on the centering rings, I used JB Weld on an AeroPack 54mm retainer. There is enough room to mount the AeroPack recessed and then the rear centering ring reinforces the internal rear of the fins.

Time for the basic construction is extremely short, about 25 minutes, not counting epoxy drying time.

As I stated before, I did have LOC/Precision to upgrade the Parachute from the LOC Standard, to a custom SkyAngle Classic II to match the Black/White/Orange & Chrome paint scheme. While the upgrade isn't really needed, I wanted a slightly robust chute.

The overall quality of the construction has convinced me that I am going to use a LOC/Precision "Bigger" Big Nuke for my Level 3 attempt with Dual Deploy.

The BT spirals, nose, fins are simple to fill with Elmer's WoodFiller and sanding with 400 grit, I used white.

Nose Cone is huge, and well built, took very little to clean up the molding flash. I decided to do something a little different on the fillets for the fins, I used 1/8" radius over bend bit in a laminate trimer. Then sanded with a palm sander going from 320 to 600 grit. Then for the fillets on the fins, I used LocTite PowerGrab. This was the first time I used PowerGrab for fillet, but it worked very well, and takes spray paint well.

While decals are not included, there are decals available on the LOC/Precision website. However I like the look of the classic Orange/White/Black/Chrome Doorknob Sandia Labs paint scheme.

The looks are classic, bold & beefy looking and to me this is a perfect kit for my Level 2 attempt.

Painting was rather straight forward. Initially used Rustoleum Professional over Rustoleum Primer for the NC.

However I had to strip the NC back to down to plastic, the primer was just not adhering to the polypropylene.

Never had this many problems with a NC before, but the previous attempt was the first time I used Rustoleum Primer. So I went back to my old method, which never failed before.

Here are the NC finish steps I used for GREAT adhesion.

  • 1) Wash & let air dry the NC
  • 2) Sand with 320
  • 3) Wash & let Dry
  • 4) Sand with 60, lightly, since it scars the NC deeply. NC is fuzzy to say the least.
  • 5) Wash & let Dry
  • 6) Sand with 180, which leaves the NC very "fuzzy"
  • 7) Apply 2 coats of Dupli-Color Automotive Plastic Adhesion Promoter with 3 minutes between coats
  • 8) Apply coat of Dupli-Color Automotive Sandable Primer (Hot Rod Grey) within 6 minutes of applying last coat of Adhesion Promoter
  • 9) Wait 6 hours
  • 10) Lightly sand with 320 to remove some of the "fuzzy" appearance
  • 11) Apply 2nd coat of primer, wait 4 hours & sand with 320 to remove more "fuzzy" appearance
  • 12) Apply 3rd coat of primer, wait 3 hours & sand with 400 to remove remaining fuzz & light scratches
  • 13) Apply 1st coat of Gloss White Rustoleum Professional as a base over the primer.
  • 14) Wait 12 hours & sand with 400
  • 15) Apply 2nd coat of Gloss White, wait 12 to 24 hrs
  • 16) Mask off white, black & orange areas.
  • 17) Apply Orange Rustoleum Pro
  • 18) Apply Black Rustoleum Pro
  • 19) Remove masking, hopefully leaving the paint on the NC and not attached to the tape.

Conditions were 66F & 52% humidity in my workshop.

Afterwards, I mounted the rail buttons.

Construction Rating: 5 out of 5

My initial flight with the Door Knob was a Level 2 certification flight, on a Aerotech J460T with at best that can be called a scratch in a 7.6 delay to achieve 6.5 seconds.

RockSim9 put it 1347' and with the 8-14 mph wind & barometric conditions, ~5 degree angle in the launch rail and everything was a go for launch.

Nice pop of the launch rail, great blue flame from the BlueThunder, that showed up nicely in the photo by Jerry Myers.

Immediately after a perfect apogee, the winds picked up, and it drifted a good bit, what seemed to be a mile.

However the Door Knob landed upright, or as Lee Barry of Merlin Missiles put it "...and he stuck the landing!"

As I was driving to recover the rocket, I could see the chute inflate and it layed over nicely.

On my second flight, using a J275W, same day, it landed a lot closer to the pad, maybe 2000 feet away. However as I walking to recovery it, I could see that the chute was inflating and picking the NC airframe up off the ground, and then dragging the airframe towards a highway about 300' feet away. Once I got to the rocket, it was 5 feet from the highway guard rail.

The NC had no peeling or flaking or scratches for that matter.

After all is said and done, I not sure I would fly a J275W in it again the delay at 6second was way to short and was still climbing when the deployment occurred. However all my anti-zippering strategies paid off.

The J460T with 6.5 second (7.6sec with scratch) is perfect for low altitude flight on relatively small field.

Flight Rating: 5 out of 5

Extremely quick build. Great quality, honestly, I wouldn't change a thing about this kit.

The only issue I had, was the NC paint issue, clearly not a LOC issue at all.

Overall Rating: 5 out of 5

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