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HomeMay 2004-1
My Baby N Project
Reflections from LDRS 22
Reprinted from May 2004 High Power Rocketry
by Charles Nozicka #6635

Having flown many M motors over the past
several years, it was time for me to step up
to the next level and build an N project! I
selected a Performance Rocketry nine-inch diameter
Honest John. I usually fly at the Bong Recreational
Area in southern Wisconsin where our launches are
limited to M impulse motors. So, I was very anxious
to build my Honest John project to fly on an N2000
at LDRS 22.

The Honest John
The Performance Rocketry Honest John "kit"
comes with an Honest John (HJ) nose cone, fiberglass
airframe and fincan. The nose cone is fiberglass
with a molded Gelcoat finish. The Honest John
style fincan is fiberglass and carbon fiber with a
nicely finished Gelcoat surface. Excellent finishing
is characteristic of the Performance Rocketry components.
The airframe was a single five-foot section of
fiberglass, nine inches in diameter. Also included
were a four-inch PML phenolic motor mount and
several plywood centering rings. This is a very basic
kit, with only basic components; the rocket enthusiast
supplies the engineering for the recovery system,
the definitive motor mount and other internal components.
The Fincan and Motor Mounts
I ordered a single four-inch diameter fiberglass
airframe for my N motor mount and designed four
outboard 38mm fiberglass motor mounts to allow
possible air-starting four J570 motors. The four outboard
and the center motor mount are all constructed
of fiberglass and were mounted in the fincan
with two centering rings. The remaining 3½-foot
section of the center motor mount was secured with
several more centering rings and main bulkhead
(Figure 1). This "main bulkhead" consists of two ½-
inch plywood centering rings that were epoxied
together with West System epoxy and epoxied to the
forward two ½-inch plywood bulkheads. This provided
a two-inch main bulkhead to which two 3/8-
inch U-bolts were bolted. Between each layer of
these plywood rings was a layer of West epoxy.

The lower motor mount within the fincan containing
the outboard motor mounts and two centering
rings was filled with Marine foam. The one-piece
fincan consists of carbon fiber and fiberglass laminate
fins. The entire fincan is covered with a Gelcoat
finish. Each fin is hollow. I reinforced the fins by filling
each with eight ounces of West slow-cure epoxy
accessed through the outside edge. The fins were
filled an ounce at a time, and the fin was then
allowed to set upright. This West epoxy provided
reinforcement to the trailing edge of each fin. The
remainder of each fin was then filled with marine
foam using small aliquots with each fin sitting on
its root edge to fill the remaining space in small
increments from the root to the outside edge.


Fig-1.jpg
Figure 1 - Rocksim Diagram

The airframe was then fitted to the motor mount
fincan assembly. This was much easier said than
done. Performance Rocketry components have an
outstanding finish, however, my components did
not fit together easily. The shoulder on the fincan
required an enormous amount of sanding to allow a
fit into the aft airframe. All of the sanding on both
the shoulder and on the inside shoulder of the airframe
was accomplished using a Black & Decker
rotary power sander. Even with power sanding tools
this material is extremely tough and required
approximately five hours of trial and error sanding
to allow the airframe to fit precisely. The fincan/airframe
junction epoxy was allowed to dry.

Next the two-inch forward bulkhead was
installed. It was epoxied to the forward center motor
mount and inner airframe simultaneously with slow
cure West epoxy. Once this dried, approximately ¼-
inch layer of West slow cure epoxy reinforced with
fiberglass filaments was poured into the airframe
forward of the bulkhead (the rocket in an upright
position). This provided another ¼-inch epoxy bulkhead
forward of the plywood bulkhead. The two 3/8-
inch U-bolts were already bolted into the bulkhead
at this point.

The Nose Cone
The aft end assembled, I began to sand the inside
part of the fiberglass airframe to fit the shoulder of
the nose cone. This is no ordinary nose cone. The
nose cone on this Honest John is five feet long with
an eleven-inch shoulder, which I cut down to eight
inches. I modified the Honest John to fly with dual
deployment; the nose cone contains a center sixinch
diameter airframe that will be used for a main
parachute bay when dual deployment recovery is
utilized. The six-inch center airframe in the nose
cone is 48 inches long and is secured in place by
foam and several plywood centering rings. A sixinch
tube coupler, 12 inches long was fitted with
bulkheads on either side with an inner 54mm airframe
to serve as the altimeter bay. The altimeters
are contained within this smaller airframe nestled
in the larger piston/altimeter bay. The entire altimeter
bay is fitted as a piston within the six-inch airframe
located in the nose cone (Figure 2). Sheer pins
secure the piston/altimeter bay. The piston/altimeter
bay is vented with ½-inch tubing to a port two feet
below the top of the rocket airframe. This allows the
altimeter bay to be unaffected by the turbulence created
by the nose cone during boost and isolates it
from the main airframe (drogue compartment) pressurization
during drogue deployment. The altimeter
bay must be isolated from the drogue ‘chute compartment
because deployment of the drogue could
interfere with the altimeter function. A resetting of
the altimeter or premature main deployment could
result. (Refer to Figure 1)


Figure 2
Dual Deployment Design
At apogee, charges separate the nose cone from
the main airframe and deploy the drogue ‘chute.
The altimeter bay as a piston remains in the upper
airframe contained within the nose cone until separation
occurs when charges are deployed at a preset
altitude allowing the main parachute to be
deployed. For this initial flight, this main parachute
bay in the nose cone was not utilized. This flight
would utilize single stage recovery at apogee; the
altimeter bay was fitted with twin Adept ALTS 25
altimeters. I have used these altimeters extensively
in numerous "Baby M" flights and found them to be
exceedingly reliable. They were set to deploy the
eight gram main chute charge at apogee.

Nose Cone Fit
Getting the collar of the nose cone to fit into the
forward airframe took a few more hours of power
sanding to both the shoulder and airframe collar.
The airframe smelled like formaldehyde during the
sanding process, so I sanded in a well ventilated
area. The high performance fiberglass airframe is
somewhat different than the Dynacom or Hawk
Mountain spiral wound fiberglass airframes I have
used. It seems to be a solid epoxy composition and
was approximately 3/16 inch in thickness. The airframe
at the collar was slightly out of round and
had to be sanded to fit the nose cone properly. When
doing this on a one- or two-inch airframe, sanding
is a minor point, but getting an eight-inch collar to
fit the nine-inch diameter airframe takes a lot of
elbow grease and time even with power tools.


 
Figure 3

Custom "Zupan" Standoffs
Since the Honest John requires airframe standoffs
for its rail buttons, I enlisted the excellent machining
skills of my friend and fellow flyer Dave Zupan.
He made several custom aluminum standoffs that
were the focal point of the airframe. As you can see
in Figure 3, these were precisely machined to fit on
the curvature of the airframe. They were beautiful!
Thanks, Dave!

Murphy's Law
This was not your simple "put together the components"
type kit. However, the end result was
worth the effort. Even rushing to complete this bird
for LDRS, the white nose cone and fiberglass fincan
section contrasted with a metal flake burgundy
main airframe. The result was beautiful, although
not perfect, due to small paint imperfections that
were the results of rushing to complete the rocket
for LDRS. As with any project, I felt I had plenty of
time. But everything ended up taking longer with
the help of Mr. Murphy. I'd bet Mr. Murphy was a
rocketeer!

Having finished painting the airframe a few days
just prior to leaving for LDRS, we were set. My
friend Ed Dewey and I were on our way to our first
LDRS experience. The Honest John would be
launched with single stage recovery with two main
Sky Angle XL parachutes to be deployed from the
main airframe at apogee. One connected approximately
ten feet from the main airframe and one
approximately ten feet from the nose cone with sixty
feet of ¾-inch Kevlar strapping between the parachutes.
The parachutes were each attached to twelve
feet of double thickness ¾-inch tubular Kevlar
recovery harnesses that had dual attachments to
both the nose cone and airframe bulkhead.

The Motor
Flying in the Midwest yields few opportunities to
fly motors larger than M impulse. This would be my
first N2000 flight in a rocket that is twelve feet long,
nine inches in diameter, and weighs 68 pounds
without the N motor. The Kloudbusters’ Argonia,
Kansas site would make a perfect area to recover
this large bird after a 9,000-foot single stage flight.
Assembling the N2000

This was my first four-inch motor. Even though I
have assembled over a dozen three-inch M motors
from AeroTech, Animal Motor Works and Ellis
Mountain, I was told the four-inch N2000 motor
would be a different experience. Although relatively
simple to assemble, the process requires "super gluing"
the forward retaining ring to the forward liner
and sanding the entire assembly to fit inside the 42-
inch long motor casing. The aft one-piece nozzle and
retaining ring must be fitted to the liner and then
the assembly must be sanded so that it again will fit
into the motor casing. I was told this would take an
extensive amount of sanding, but after building the
Honest John this sanding seemed very minimal. The
motor was easy and straight forward to assemble,
even in the 100º Argonia heat. I assembled the
motor in approximately thirty-five minutes at the
launch site.

Some Like It Hot
Early August in Kansas the weather can be unpredictable.
However, our LDRS experience, except for
extreme heat, was excellent. We had sunny skies
and moderate winds each day. Except for an occasional
dirt devil and 105º+ temperatures, the
launch weather was perfect. The hospitality of the
Kloudbusters Club was truly outstanding. The entire
pad managing crew and launch administration was
professional, hospitable and friendly. We could not
have had a better experience.
fig-a.jpg

Launch Day

My launch occurred on

Saturday of LDRS week.

Having helped several of

my Tripoli Wisconsin

Association (TWA) fellow

members launch their rockets

all day, I was getting

anxious. Now it was my

turn! Our group had several

notable flights, including a

perfect M3000 Dynacom

Tarantula flight by Ed

Dewey. Well, almost perfect…

failed motor retention

dropped the AMW

motor casing 10,000 feet

into a farmer's field, but it

was recovered intact! There

was the excellent boost of

Greg Grabecki's N2000

flight on his (Dynacom

components) Estimated

Prophet. Failure to secure a

quick link resulted in the

main airframe, again,

assaulting the farmer's field

from 20,000 feet! Greg was

"grateful" to find the fiberglass airframe and electronics

bay in a near by field. The N motor casing

and electronics were completely intact. Check lists

are important even for experienced fliers.


My Turn

Now it was my turn and we drove the Honest John

out to the 60's series pads, which were for M and N

projects. These were the so-called "medium sized"

projects for this LDRS. There were many large cluster

projects that were flown all week from the

"away" pads. When did a seventy-pound "N" project

become medium sized!? With the help of Chuck our

pad manager, the Honest John was easily placed on

the extreme rail. Our initial countdown resulted in

no ignition! O man, I was tired, hot and nervous!

This igniter failure necessitated driving through the

LDRS camp back out to the launch site to replace the

igniter. Then the second countdown again resulted

in another "no ignition!" But a short pause and

another countdown by the LCO using the same igniter

resulted in the N2000 roaring to almost immediate

pressure. The Honest John majestically took to

the skies in a perfectly straight boost. The large

rocket could be followed with the naked eye through

apogee. At apogee the eight grams of ejection powder

separated the nose cone from the airframe and

the two parachutes deployed and the nose cone

began its descent. However, at that moment the airframe

separated from the main airframe harness.

The airframe came in ballistic into an empty

farmer's field (noting a trend here?) approximately a

half a mile from the launch site. Several witnesses

saw the forty-pound airframe come in straight into

the farm field where it "lawn darted" itself into the

soft dirt.


Search and Recovery
Later examination revealed the sixty-foot length
of ¾-inch Kevlar strapping broke during deployment
at apogee. It did not appear to be due to cutting from
the airframe as there was a large amount of fraying
at the broken fragment—approximately twenty feet
from the end of the harness. It appeared to be a
clean failure of the Kevlar.

The airframe forward section was buried almost
three feet into the ground to the point of the main
motor mount bulkhead. This forward airframe was
snapped off where it entered the ground. After
removal of the buried recovery harness from the
quick links, the aft end of the airframe were "easily"
pulled from the ground and carried away; as easy as
could be after a long hot day. It was now after 6:00
PM and the 110º heat had given way to cool (88º!)
evening breezes.

The four-inch fiberglass motor mount survived
the "ballistic airframe recovery" from almost 10,000
feet. The main fincan and motor mount are completely
intact and will be reused to rebuild the
Honest John—this time with carbon fiber
Performance Rocketry components for the new airframe.
The toughness of these components is
incredible!

Other rocketeers recovered the nose cone and
parachutes several days later as they drifted miles
off in the distance. The excellent launch and boost
were captured by Nadine (Photography by Nadine)
who provided these excellent launch pictures.

Epilogue
All in all the launch of the Honest John was a success.
The bird will be easily rebuilt to fly with dual
stage recovery with the main being deployed from
the nose cone.
What have I learned (or remembered) from this
flight?
• It's awful hot in Kansas in August.
• Drink plenty of fluids in Kansas in August.
• Bring a lot of sun screen to Kansas in August.
• The Kloudbusters Prefect and this LDRS
experience were fantastic. These people couldn't
have provided a better launch.
• Any N flight is a sight to behold, even though
there were numerous such flights at LDRS, each
one was breathtaking.
• The Performance Rocketry products and the
service from Curtis Turner are outstanding. These
components are not only beautifully finished but
they can sustain a lot of abuse.
• It's the good friends that make HPR enjoyable—
thanks to Ed for helping me dig out my "lawn
darted" Booster from that farmer's field, on that
long hot Saturday afternoon! Not to mention
helping to carry the 35-pound "remains" a half
mile back to the van!

Website References
www.photosbynadine.com (Photos by Nadine)
www.tripoliwisconsin.org
(Tripoli Wisconsin Association)
(Performance Rocketry)
www.adeptrocketry.com (Adept electronics)
www.apogeerockets.com (RockSim Software)
www.b2rocketry.com (Sky Angle Parachutes)
www.kloudbusters.com (Kloudbusters)




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