Fire in the Sky '05 hybrid launch report

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andrewm57

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Over the Memorial Day weekend, Washington Aerospace Club held the 6th
annual Fire in the Sky launch at Mansfield, Washington.

Day time temperatures were in the high 80's to mid 90's, with light to
moderate breezes mid-day, and calm mornings & evenings. 223 flights,
plus more EX launches. An estimated 150 flyers, and 500+ attendees.
Solar & stellar gazing courtesy of local astronomy clubs, and a ballon
sat launch to 87K feet!

I had 2 specific goals regarding hybrids: 1) prove that hybrids are
reliable to launch; 2) test several manufacturers motors head-to-head in
the same airframes. The tests were the Ratt K240 vs. the new West Coast
K460 in 'Mjollnir', my faithful modified BSD Thor, and my new Sky Ripper
Systems I119 vs. my unflown West Coast Hybrids I110 in 'Laughing
Matter', a scratch 3" x 6.5' 3FNC.

On Saturday morning, I flew my BSD Thor on a Ratt K240. Normal ignition
delay; typically awesome howling liftoff & long burn; flight arced
upwind & slightly crosswind to the SE; recovered < 1/4 mile SE of the
pad. I beleive this was my 20th flight of the Ratt K240!
Missleworks RRC2X 40K = 4249'
GWiz MC = 4388'
Supply tank = 780 psi
Fill time ~= 45 secs
https://www.e2scopes.com/rockets/FITS_2005/source/dsc_0057.html
https://www.e2scopes.com/rockets/FITS_2005/source/dsc_0063.html
https://www.e2scopes.com/rockets/FITS_2005/source/dsc_0064.html

Courtesy of West Coast Hybrids, I flew the same airframe for the first
demo flight of their new K460. We attempted to launch late Saturday
afternoon, but had problems with a fill solenoid, then suffered a fill
line blow out due to excessive supply tank pressure. Sunday morning
after the tank cooled overnight, we launched from the awesome West Coast
launch trailer hooked to my pad & rail. Slower than normal pad ignition
using the WCH low voltage high current GOX & steel wool ignition; sat on
the pad for several seconds; slower than normal liftoff for WCH motors;
moderate 'buzz' and a few 'huffs'; flight arced upwind to the NW;
recovered 1/2 mile NW by the main road; suffered booster coupler damage
from finding the median rocks instead of the wheat field :( Post mortem
on the motor showed that instead of burning off the central injector,
the fill line pulled out of the compression nut, which led to higher
than normal NOX injection (greater injector cross-section), causing the
combustion instability. Assumptions are that there'd be a slight
increase in performance and definite combustion stabilization with
correct injector burn off.
Missleworks RRC2X 40K = 4809'
GWiz MC = 4724'
Supply tank ~= 740psi
Fill time ~= 60 secs
https://westcoasthybrids.homestead.com/mans2005.html
I will have the downloaded GWiz MC data later.

The winner on the K flights is the new West Coast K460! But I still love
the Ratt howl :)

Range duties and high temps/tank pressure kept me from flying more on
Sunday.

Monday morning the temperature was more reasonable, so I prepped
Laughing Matter with a SRS I119. Very nice motors, and simple to
assemble. Nominal ignition; moderate liftoff speed; absolutely stable
combustion (somebody said 'hey, that sounds just like a solid'); flight
arced NW; recovered 100 yds NW.
Missleworks RRC2 = 2336'
Supply tank = 680 psi
Fill time ~= 30 secs

Since that flight was so simple, flight lines were short & temps were
still moderate, I turned around Laughing Matter with a WCH I110 in under
2 hours. The motor went together easily, and I cheated by using a SRS
24mm preheater & Quickburst, which fit perfectly into the WCH bulkhead.
Very fast ignition; much faster liftoff speed than the SRS; definite
hybrid scream; flight arced NW; recovered 150 yds NW.
Missleworks RRC2 = 2336'
Supply tank = 740 psi
Fill time ~= 30 secs

Yes, that's right, the I flights are a dead heat! Both hit exactly
2336'. And yes, I didn't believe it at first, so I've since ground
tested the altimeter with a yogurt container barometric chamber, and I
get different readings.

All my flights off my pad were literally setup, fill, fire, recover. I
received several comments on how simple it all looked...

Other hybrid flights: Bill Clugston tried to get a ProPoly motor
launched, but ran into diffulties, but he did get off a nice flight on a
Ratt H70. At the alternate EX site on Sunday, the West Coast crew and
OROC members flew a new secret variant of their M motor in a minimum
diameter bird with a video downlink in the payload. The launch and first
8 seconds were nominal, but at about 10K', "something" happened that
completely destroyed the airframe and no pieces were recovered.

On a separate note, my thanks to Doug Pratt. He got a brand new launch
box into my hands the day before I left, and it performed flawlessly,
not only for my hybrid flights, but the box, my QaudPod & 10' rail were
used thru the whole weekend for a mid-away pad with no problems,
including a cluster of QuikBurst ignitors. Awesome stuff!

And kudos to Launch Director Jim Wilkerson, the core WAC crew, and
helpers from both SPARC & OROC. They made the launch what some are
calling the best ever in the PacNW.

Lastly, my deepest thanks to the town of Mansfield & Mayor Tom Snell.
They have gone far beyond the call to mow the field, provide
porta-potties, bring in the Lions Club food trailer, the Garden Club
cooked a lasagna dinner Saturday night, "Welcome Rocketeers" lit up on
the high school signboard, Tom's private land for the EX site, showers
at the high school gym, hardware & grocery store 5 minutes away in
town... I'm sure I've forgotten many details of their commitment to
support the launch, but this is the cats meow for a launch.
 
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