If You Think Rockets are Toys, Better Stand Back : Hobbies: Enthusiasts put on spectacular shows as powerful models grow longer than cars. Some miles-high launches require FAA clearance.

Toy rockets used to be something found in your Christmas stocking. They were like firecrackers on a stick. Just light the fuse and they would spurt off in a fiery arc, maybe half the distance of a football field.

Then model rocketry became the stuff of basement tinkerers and kids with kits that would send a missile several hundred feet into the air.

Now, more than two decades after Neil Armstrong walked on the moon, even toy rockets have exciting firepower.

Today’s model rockets can be as long as a sedan and as heavy as a small child. They can be launched up to three miles high, requiring clearance from the Federal Aviation Administration.

“This is about as close to Cape Canaveral as you can get without being there,” says Sam Gordon, an amateur rocketeer in northwestern Pennsylvania.

Even some astronauts who have blasted off from Cape Canaveral started as amateur rocketeers. Space shuttle astronauts Jay Apt of Pittsburgh, Jerry Ross of Crown Point, Ind., and Mike Mullane of Wichita Falls, Tex., all credit model rocketry for leading them into outer space. Apt even carried two small rockets with him aboard the Atlantis in April.

The local chapter of the Tripoli Rocketry Assn., the nation’s only high-powered model rocketry group, emulates NASA’s launch techniques behind a produce stand on donated farmland near this small town about 100 miles northeast of Pittsburgh.

There are long countdowns, safety checks and cheers when a rocket “clears the tower.”

“The roar of the engines at launch . . . it’s just an exhilarating experience,” Gordon says.

Model rocketry has become big business.

Organized model rocketry started in 1958 when Vern Estes, now 61, formed Estes Inc., the world’s largest model rocketry company, says Mary Roberts, the company’s director of marketing.

Estes, based in Penrose, Colo., developed the first machine to mass produce model rocket engines. Black powder remains the primary propellant, packed tightly into cardboard cylinders that are thrown away after one use.

Estes’ rockets, which weigh less than a pound, can reach a top altitude of 1,500 feet. A starter kit--including a small, single-engine rocket and launch pad--costs about $13. Estes’ largest model--a five-engine Saturn V replica--runs about $50.

The company estimates that about 5 million people, mostly teen-agers, have launched Estes rockets about 300 million times in the last 34 years. Kits are sold at more than 6,000 stores around the world.

“The entire hobby was designed so that youngsters could learn about science, aerodynamics and other applications,” Mary Roberts says.

But as the youngsters grew up, so did their appetites for bigger rockets that would go faster and higher, she says.

The market for high-powered rockets had evolved but had few suppliers. That didn’t stop Sam Gordon, a reporter at an Oil City radio station.

Gordon, 41, says that as a teen-ager in 1965 he used to mix two ingredients into a tube, then pack the mixture tightly to make rocket engines with more thrust.

“Actually, I was a ‘basement bomber,’ ” he says. “I used to launch in our back yard and, in all honesty, the neighborhood was terrified of me. One of my rockets ripped off some shingles from a house and tore off a downspout.”

High-powered rocketry wasn’t formally organized until 1985 with the incorporation of Tripoli. Founded in Pittsburgh and now based in St. Petersburg, Fla., Tripoli has about 1,700 members nationwide, says Bruce Kelly of Orem, Utah, editor of the association’s journal, Tripolitan magazine.

LocPrecision Inc. of Macedonia, Ohio, which sells high-powered rocket kits, estimates that its average customer is 25.

“These are the people that used to be into Estes rockets,” says Debbie Schultz, company vice president. “They want to build something big. Every boy wants a toy. Well, it’s a big boy’s toy.”

The largest rocket LocPrecision offers in kit form is “The Bruiser,” nearly 7 feet tall and 8 inches in diameter. The 7 1/2-pound rocket can travel at supersonic speeds and reach altitudes of several thousand feet, she said.

Hobbyists who want more blast for their buck are building their own rockets up to 42 feet tall. Some can reach altitudes of 15,000 feet, Gordon says.

High-powered rockets are fueled by ammonium perchlorate, the same fuel used in the space shuttle’s solid-fuel rocket boosters. All high-powered launches require FAA approval.

While the launch of an Estes rocket produces a fast, ripping “swoosh” sound, the launch of a high-powered rocket is more like a rumble.

Mrs. Roberts declined to reveal Estes’ 1990 income, but she said it is a multimillion-dollar business.

High-powered rocketry can be costly, with prices ranging from about $25 to several hundred dollars.