Rocket Trails: Boost Gliders: Winged "Birds"
March/April 1963 American Modeler
gliders grew in popularity in the early 1960s and then seemed to
ebb by the end of the decade. I'm not sure why. Maybe the rocketry
purists drove a more timid Boost Glider (B/G) bunch into the background.
I remember getting some pretty nice flight out of my
Estes Falcon glider. This article from
the 1963 March/April edition of American Modeler mentions Vern Estes'
efforts to foster the boost glider craze by modifying what I knew
as the Gyroc to perform as a glider once
the engine cartridge was ejected, rather than recover in its original
form by creating a high drag profile via a rapid spin. Rockets,
like free flight model airplanes, need a lot of open space if altitudes
of more than a few hundred feet are planned. Sure, you can estimate
the angle for the launch pad tin hopes of firing upwind enough to
allow the rocket to be blown back near the launch location, but
I can tell you from personal experience that just a model airplanes
can be unexpectedly snatched by a passing thermal and carried away
to the hinterlands, so too can a model rocket hanging on a parachute.
In fact, since I grew up on the East Coast near Annapolis, Maryland,
where large, open spaces are rare, I always configured my parachutes
(small diameter or larger with hole in the middle) to bring the
rocket back down ASAP. The problem with that is then you don't get
to enjoy watching the rocket float down for very long.
by G. Harry Stine
BOOST GLIDERS: Winged "Birds"
Five years ago the only model rocket range
in U.S. was at Green Mountain Proving Ground
near Denver. Chuck
Olson and Del Hitch load birds onto rod launchers.
A group of R/C and free-flight fans showed up on one of the
NAR model rocket ranges this Fall. Had read this column and decided
to see if it was for real. When confronted with a boostglider and
explanation of its working, one hardened aeroplane builder remarked,
"Look, I've been building model airplanes for 20 years! These things
can't possibly fly! They've got all the gliding characteristics
of a brick!" Whereupon an undaunted modrocknut slipped an engine
in one and sent it aloft for a 57 second flight while eyes popped
like champagne corks.
"You're keepin' it up there by mental
telepathy! It can't fly like that!" objected one of the plane lads.
After five more B/G's hit for the blue and did the same, the airplane
builders retired to their drawing boards.
How times have changed! Today (above) modrocknuts ready modern launch
White Plains, N. Y. Hundreds of ranges now, plus 30,000
New In B/G. Vern Estes modified a standard
Space Plane and flew it to a Senior National Record of 1 :44 at
NARAM-4. He takes a regular Space Plane and screws the elevons down
flat. Out comes the standard engine block. Off comes the nose cone...
this is replaced by a hollowed-out round nose cone. New cone is
glued on. Spin tabs on rudders are removed, as well as elevon elastic.
Modified bird must be flown as follows: empty engine casing
with nozzle removed is taped onto front of loaded engine, and combo
is slipped into body so that empty tube comes up against base of
nose cone. This puts weight of an empty engine casing up front.
When engine ejects, it pulls empty casing out with it, jerking weight
out of nose. B/G then flips over on its back and glides like crazy
with no elevon setting at all.
I built one like it, gluing
elevons in place and leaving off everything not required. My modified
Space Plane turned in 47 seconds with a 1/2A.8-2 engine. Vern now
claims an unofficial time of 1:57 with a "modified-modified" job.
Many modifications showing up on Centuri "Acro-Bat" B/G,
too. Mostly increased wing area, movement of area aft, anti-warp
strips, lighter nose cone. Anti-warp strips are pieces of sheet
balsa butt-joined to wing or elevon edges (as shown in drawing)
with grain running 90-degrees to main wing grain to prevent warp
and add strength. Needed if increased area is used. Have seen modified
"Aero-Bats" turn in 50-plus seconds with half-A engines, too.
RR/C gear presently going into a B/G by Marshall P. Wilder of CBS
Labs in Connecticut: Ontarion O-21 receiver and CitizenShip Model
SE escapement for rudder-only control during glide. CG "Venus" tone
transmitter being used. Rocket-borne gear weighs in at a shade over
3 ounces with batteries. Escapement will actuate rudder, not elevons;
rudder and elevons to be locked in zero incidence during powered
flight. Expected to fly when weather clears in March; R/C flights
will be preceded by trim hops using clay to simulate weight of radio
gear. At the speeds B/G's are capable of flying, who wants to risk
his gear on the first flight?
New Model Rocket Company.
Scientific Amateur Supply Co., P.O. Box 732, Ogden, Utah, is headed
up by my old rocket-shootin' buddy and Thiokol propellent chemist
John Rahkonen. Outfit has a line of plastic nose cones, tracking
aids, electrical igniters, and two rocket engines. One produces
an average thrust of 1.3 pounds for 4 seconds; the other, 2.5 pounds
for 6 seconds. Can be had with time delay and ejection charge.
These advertised specs are being checked by the NAR Testing
Gay Traveler. I have been to
gay Paree in the cause of international model rocketry. The National
Aeronautic Association submitted the NAR's rules to the Federation
Aeronautique Internationale in Paris. Committee on aeromodeling
will consider them for internats rules.
The Iron Curtain
countries held their first rocket meet in Krakow, Poland last summer.
Looking forward to the possibility of competing with the Russians
in the scale events and getting a peek at their scale substantiation
data! I imagine that CIA would like to do that too! Remark about
this from Del Hitch at NARAM-4: "Russians will probably show up
with scale models of American missiles, giving substantiation data
that American modelers can't even get because it is top secret here!"
Magic Batt? If you want miniaturization and portability
in your electrical firing systems, get a set of size D sintered-plate
nickel-cad batteries, Many types of nickel-cads are pressed-plate
types that will not throw any more current than a standard dry
cell. But sintered-plate jobs are available from the Gould-National
Corporation, New York City.
These little bombs, expensive
as all get-out, are rechargeable, will last forever, are the same
size and weight as standard flashlight cells, will throw a short-circuit
current of 50 amperes with a shorted cell voltage of 1.1 volts!
Four of them in series will fire a nichrome igniter in about a second,
and will do it over and over and over again. When they run down,
recharge them again for 16 hours at 400 milliamperes with something
like an HO train power pack.
I have a complete firing system
housed in a 3" x 4" x 5" aluminum chassis box, batteries and all.
There is little you can do to harm these sinteredplate powerhouses
- they are sealed and will stand a great deal of abuse. When you
are not using them for firing model rockets, you can always slip
them into a flashlight. Or maybe use them as booster batteries to
start your car on cold mornings? Start a car with four flashlight
cells in series? Sure, with sintered-plate N-C's.
Lack of Ranges. Lots of young modrocknuts ask about
how to find a place to fly. In the first place, the problem isn't
unique to model rocketeers. The model airplane boys have the same
trouble. I say to all, you don't stand much chance without adults.
You gotta have 'em. They are better at making the necessary contacts,
talking to the right people, agreeing to accept the responsibility
for your little jaunts into the troposphere. There are no pat solutions
to the flying space problem. Each locality has different conditions.
Read the reports in this magazine to learn how some model airplane
clubs have licked their flying site difficulties.
As a matter of fact, check all the articles in American Modeler.
You'll pick up lots of tips that can be applied to model rockets.
This rocket hobby grew out of model aviation, there are techniques
common to both. I would like to see closer coordination and more
swapping of information between the two activiries. It would be
good for both.
Questions/Answers. Ned Hood
of Bevery, N. J. wants more data on the HansScott movie camera
rocket. Okay, Ned, you'll get it in future issues. Also more about
the R&D projects at NARAM-4.
Glenn Ford (not the
movie actor) of Granada Hills, Calif. queries about Class E and
Class F engines. All Coaster engines are Class F. Some of the new
SASCO engines are Class F, perhaps Class E also when testing shows
classification. Class E engines have 4.01 to 8.0 lb-sec. total
impulse; Class Fare 8.01 to 16.0 lb-sec,
a 36-inch launch rod made from 1/8" music wire usually won't take
a model weighing more than 6 ounces because (A) the short length
of the rod doesn't allow the model to gain enough air speed before
leaving the launcher, and (B) the slim rod isn't stiff enough for
heavy jobs because it can be easily bent. For models weighing over
6 ounces, I usually use a 5' long, 3/16" steel rod - or a 6-foot,
1/4" diameter steel rod. Some models with high thrust-to-weight
ratio can be flown from 3-foot rods, but it is better not to take
chances. If the initial thrust-to-weight ratio is less than 5, or
if the engine is a slow starter that doesn't build thrust quickly,
use a long rod.
Ram Jet. Hottest propulsion
news in a long time involves a ram jet that uses compressed air
and produces thrust while standing still. Invented by Dr. Henri
Coanda of France, the unit is simple, has no moving parts, works
on 7.5 psi .air, uses mass flow induced by creating a high speed
boundary layer. The Coanda Duct has been used in France for many
things-to blow fresh air into mines, for example. Since no combustion
is involved, there is no heat. Operation should be virtually noiseless.
As I get additional details on this gadget, I will
pass them on. Dr. Coanda is a living legend of aeronautics and fluid
dynamics, having flown the first turbo-jet airplane in 1910 and
having designed, among other things, the Bristol F2B "Brisfit" WW-I
fighter. Dr. Coanda is still going strong.
Birthday! Model rocketry and the NAR celebrating their
joint Fifth Anniversary. Born with the Space Age in 1957, our hobby
has come a long way. Perhaps on this occasion the Old Rocketeer
may be permitted to ramble on back a bit. Model rockets flying over
the Nebraska plains and the New Mexico deserts when Orville Carlisle
and the O.R. were the only two model rocketeers. Del Hitch and O.R.
riding around in a car trying to find a place to fly, finally letting
a few go in a bulldozed field that is now covered with houses near
the Martin "Titan" ICBM plant in Denver. The search to find somebody
to mass-produce model rocket engines so we wouldn't have to load
them ourselves, finally encountering Lawrence Brown in Missouri
(since gone on the long trajectory).
I still have my first
model rocket so I took out some of the original engines the other
day to see if they were still good. When run on my static test stand,
these 5-year-old solid propellent model rocket powerplants performed
as well as their companions did right after they were made... which
indicates the fantastic reliability of our power packages.
Posted November 17, 2012