Saturday, May 30, 2009

Buzzard, Buzzards, & more Buzzards

This is the cover of Bill Dean's Book of Balsa Models.
The plane on the cover is called  the Buzzard.
I fell in love with the Buzzard from the magazine ads. for this
book long before I ever ordered it. I modified many, many
North Pacific Sleek Streaks into Buzzards over the years. 
And yes, they flew better than stock Sleeks.
After I got the book, I built two accurate to plan Buzzards,
then a somewhat larger one. Finally, my flying partner Steve G.
and I were getting ready for a big free flight contest, hosted by
the Brooklyn Skyscrapers  at an abandoned WWII airfield in
New Paltz, New York, on 4th of July weekend 1976. We got
dropped off, and camped the three days by ourselves, right on
the runway. That was one of the best weekends of my childhood.
Anyway, we wanted something extra to compete with and didn't
have a lot of time, so we decided on Unlimited Rubber [not many
rules] and upscaled the Buzzard to around a 4ft wingspan, but still
using a lot of the same techniques. No landing gear though, since
we'd be flying in tall grass, and the rubber, once unwound, sagged
over a foot below the plane anyway. It flew great!  Unfortunately,
on the 3rd test flight or so, we stuck it in a very tall pine tree.
Oh well, no time to build another.  Too bad too, it would've got
us a trophy in our age class for sure.

Here's the real kicker to this story.
Our Grandmother Nana unloaded her 8mm home movies on us
when she moved south. Eventually we went through those old films
and ran across a family reunion/thanksgiving? from around 1964 or
'65.  There in Nana's backyard, is my cousin Charlie and myself,
both around 4-5, chasing after Charlie's dad, Uncle David while
he's flying a Buzzard!
Haw! No wonder I was so attracted to the design.
I have vague recollections of that get together, but that ain't it. I
never got to ask Uncle David about it 'cause he lived in Chile.

The book was published in the USA by ARCO publishing  which
appears to be out of business. A quick online search shows that it
can still be found, as well as the original British version, which is
called Eagle's Book of Balsa Models. I don't know of any
differences between the 2 editions. Look for it [them] on Amazon.
There are a bunch of cool models in it, including 4 Jetex vehicles
and a sailboat. If you have kids you want to introduce to real model
building, or if you're still a kid at heart, this is a fun book.

Oh yeah, check the typo on the cover. That's supposed to be
Skyray, not Skyway. A profile model of the Douglas jet fighter.
Another great model plan we built several of.

Saturday, May 23, 2009

A Really Big Pair

I finished making these 2 nozzles for longtime rocket buddy, Don C., a few days ago.  They aren't the biggest nozzles I've worked on, I once helped design and produce a 2 piece nozzle that was 8" dia., but these are the biggest that I've CAD designed myself and turned on my own lathe.
Eureka! ZZakk's Lab has produced monsters!  Bwa-ha-ha-haaa!!!  

Ahem, in the lower pic they're posed with one of the Cesaroni Pro98 motor cases that they were made for, and the fabulously expensive spanner tool that Cesaroni now sells for installing the retainer rings.  Actually, just about anything you need or want for 4" rocket motors is fabulously expensive. The Cesaroni cases are designed and licensed [fabu dinero, I'm sure] to operate with Aerotech reloads as well as Cesaroni reloads.  This is a good thing since it increases the versatility of the hardware.  My friend however, is currently making his own Moonburn reloads for the cases, and using RCS/Aerotech supplies in the process.  The RCS 98mm nozzles are $44 each for a single use, and in the case of the 5/8" throat on the right, would still need to be custom bored anyway.  My graphite nozzles are completely reusable, and if need be, I can remachine the throats later if they get too crusty, chipped, or a larger throat is desired.  Some internal fuel volume is sacrificed but I added a much better expansion ratio, between 5:1 & 6:1 instead of only 2:1.

Last year, I looked long and hard at the costs of larger motors.  I decided to go with 3" hardware since it costs less than 4" every step of the way, despite the longer length needed for the same power.  Plus, being a hybrid flyer, a 3" combustion chamber is plenty big enough, AND, I'm already used to building rockets that take relatively long motors.

More recently, I rescued a belled 3" case from another friends recycling pile. Thanks RK!  

I trimmed the ends off, but still need to cut new snap-ring grooves.  It's kinda short, but I'm on my way!  When I get around to buying new 3" motor cases, I'm gonna give the
Cesaroni hardware another good look.

Monday, May 18, 2009

Fly-Back Boosters, Reprised

Last week, the USAF released study information concerning
lower cost, shorter lead time, access to space. I think
it's funny that the USAF was studying similar proposals
back in 1988. Amongst more familiar designs were the first
drawings I'd seen of fly-back booster systems. They add
a lot to the liftoff weight, but reusability is greatly
enhanced by not dipping the booster in salt water, like the
shuttle strap-ons. Other typical features include motor
commonality, where possible, and limited reusability.
An example would be; useing the motor[s] X number of
times in the fly-back booster, then transferring them to
the disposable core stage[s] for one last trip.

I am by no means bitching. I like these systems. However
it is somewhat amusing how history repeats itself, only at
twice the price now. There are no technical hurdles to
overcome now, and there really weren't any then either.
The Air Force isn't asking for peak performance. Larger
base capacity makes up for moderate performance coupled
with higher reliability. The difference between pro-stock
class and top-fuel dragsters or funny cars at the drag strip.

The big difference between the old fly-back system and the
new, is that with the old, it was primarily a very heavy lift
system [105,000-160,000 LB/LEO], while the new approach
is part of a fully rounded low to heavy capacity [peak 64.000
Lb/LEO] program. I like modular systems, especially when
there are enough modules to fully utilize the concept.

Stay tuned for some modular space system gripes, coming soon.

Monday, May 11, 2009

Not so Awesome Blossom

I built the Awesome Blossom a few months ago.
Due to the drought and county burn bans and such
I didn't get to try it till last weekend. It's the
smallest monocopter I've built to date and was
meant to be powered by a ground blossom firework
which is installed in the picture. I got the idea
for the tubular hub from Art Applewhite's Helix
copters. When I found a tube that's a perfect
fit for a ground blossom, it just had to be done.
The wing is 7"span x 2"chord. It doesn't look it in
the pic, but the wing has about 8 deg of up pitch.
The flybar is a bamboo skewer.

Well, it didn't work.
It spun on the launch pin for about 5 seconds, but
never developed the speed it needed to takeoff.

A ground blossom normally gets lit and is set on the
ground, it then spins madly in a more or less
spherical pattern while the flame changes colors. As
fast as it spins by itself, I had high hopes for it
pushing a small monocopter, but no joy.

I've already built a new T-shaped 13mm motor mount
to plug in to the existing hub tube so that it'll
use modroc motors now, and still have an adjustable
motor pitch capability.

Thursday, May 7, 2009

Big News From Adept Rocketry

Adept Rocketry is celebrating its' 20th anniversery in
business. 20 good years IMO, I've been a customer since
the beginning.
Adept, while not the first producer of rocket electronics,
including altimeters, really set the benchmark for the
hobby, both then and now.
Tommy Billings, the owner, has also announced that he
has aquired some production and testing equipment. With
this enhanced in-house production capabilities, Tommy has
been able to reduce some prices, and is going to start
releaseing upgraded versions of his older, out of
production electronic products.

While I do have a few products from other manufacturers,
I have always been an Adept supporter, so I'm quite pleased,
and look forward to the re-release of a couple items I have
not been able to find adequate substitutes for.