Rocket Trails: Boost Gliders: Winged "Birds"
March/April 1963 American Modeler
Rocket-boosted 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.|
Rocket Trailsby 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 rack in
White Plains, N. Y. Hundreds of ranges now, plus 30,000 fans.
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 Committee.
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,
Also, Glenn, 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.
Happy 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