. . .WHOOOSSHhhh

YES................ohoh.. wait for it..3...2...1..(a distant "pop") a bystander says "ah cool two chutes, the wind will bring it right here".

RUN VAXLINK2 this should something new bold and emphasis.

Doyou like model rockets?

How bad can it get?

FREQUENTLY ASK QUESTIONS Q. How high can they go? I mean to outer space?

A. Yes they can go in outer space. In fact there is a challenge to be the first private group to send a 2 Kilogram payload 200 Kilometers into space. The current altitude record is 75 Kilometers and the award is $250,000.It is called the CATS prize.

Q. What makes it go?

A. The chemical reaction of the burning fuel increases the pressure inside the engine. This expanding gas is exhausted out the rear of the nozzle. The reaction of the pressure difference between the upper and lower parts of the engine moves the engine in the direction on higher pressure.

Q. What is the fuel?

A. Black powder is used for the low power kits, and ammonium perchlorate for oxidizer with rubber as the fuel are used by the larger rockets. The engines are rated in an alphabetical way so that an "A" engine is the standard and each successive letter is twice as powerful. So an "E" engine is 16 times stronger then a "A" is. Currently "O" is as large as they get and "N" & "O" sizes need to be custom made by a specialist in explosives.

Q. Can they brake the sound barrier?

A. Yes. Any thing that moves that fast will make a shock wave that is a sonic boom, but it is hard to do. (this is another fun thing to try)

Q. Where can I launch rockets?

A. Any open area that is at lest 5 Miles from an airport and meets the N.A.R.* safety code. *National Association of Rocketeers (one the groups that is entrusted by the powers that be to keep the sport safe)

Q. Where I can find more information? Who can I fly with?

A. Iowa Society of Amateur Rocketeers is a new club that is centered in Des Moines has a web site or email me jshearer@iastate.edu. I will try to post answers here.

Q. How much does it cost to get started and where can I find the things I need?

A. Starter sets and individual kits can be bought at K-mart, Wal-mart, and many Hobby Shops in Ames. The cost is as low as $3.00 to as much as you are willing to spend, but most kits cost from $5 to $20. You also can try to make your own models as I some times do.

Q. What are some safety limits or regulations that I must fallow?

A. 1. If your rocket is under 1lb. at launch the only things to watch for is that one about airports, and the size of the landing field. 2. When you plan to launch a bird that is between 1 & 3.3lb. you will need to contact the closest FAA office 24 to 48 hours before you launch. 3. To launch anything larger then 3.3lb or over "G" power you will need to be certified through N.A.R. to T.R.A.

Q. Who are all these organizations and how do they affect the rocketry hobby?

A. DOT (Dept. of Transportation) regulates shipping of rocket motors and reloads.

CPSC (Consumer Products Safety Commission) regulates what may and not be sold as a 'consumer' items at the retail level.

FAA (Federal Aviation Administration) is responsible for airspace control and regulates flights of rockets that exceed 1 pound and enter FAA regulated airspace.

NFPA (National Fire Protection Association) makes recommendations for use of non-professional rocket motors. Although the NFPA only makes recommendations, most state and local laws concerning the use of model rockets are based, at least in part, on NFPA recommendations; especially NFPA 1122. The NFPA also has a draft definition and safety code for High Power rockets, NFPA 1127.

BATF (Bureau of Alcohol, Tobacco and Firearms) has responsibility for regulations concerning storage and use of explosives. This agency has taken a recent interest in looking into how high power rocket motors are stored and used.

ATC (Air Traffic Control) You must notify the nearest FAA ATC center prior to flying Large Model Rockets or High Power Rockets. This part was copied from the r.m.r. faq.

Q. Where can I see some of these large rockets fly?

A. That's easy just come to FIRE ON THE FARM April 4th & 5th. ISOAR and THOR, our sister club from Nebraska are planning a regional launch.

NOW SOME ROCKET SCIENCE

(your rocket will test you on this)

Stability!!! The best way to be sure of a stable flying rocket is to use a kit. If that's not good enough the physics involved is that the center of gravity must be one diameter or more forward of the center of pressure. Center of pressure is computed by adding all of the surface area of the silhouette then finding the center of it. Center of gravity is found by simply balancing the missile on it's side. Weight can be added to the nose of an unstable rocket to make it more stable.

Thrust!!!! As noted in the faq the action of the gas exiting the aft of the engine causes the reaction of the rocket moving foreword. THIS MUST BE LARGER THEN ALL OTHER FORCES WORKING AGAINST THE ROCKET.

Drag!!!! This is the effect of resistance on the craft moving through the viscous air. To reduce the drag on a ship builders try to make all external surfaces as smooth as possible.

Gravity!!! The force of attraction between any objects with mass. This is old stuff.

Inertia!!! Newton's law of inertia states that an body at rest tends to stay at rest and that a body in motion tends to stay in motion unless acted upon by a force. Pretty simple ha?

HOW TO BUILD A STAR CRUISER

Kylie my 5 year old daughter helped in selecting the design and materials that I will use on this project. When I suggested a star cruiser, she and I did not have the same vision. Her interpretation was that of rocket with stars on it. You can imagine my idea.

Thinking hers was the cutest of the two ideas, we decided to make the fins in shape of half stars so when viewed from the side this 4 finned rocket will look like this.

Retrieving a sturdy 1 and 1/8" card board tube from my stock, I cut about a foot long body tube by holding an exacto knife against the tube while turning it in a piece angle iron. Using an old phone card as a putty knife I started filling the spiral groove with wood filler.

Next I cut some 2" Styrofoam block to the rough shape of our desired nose cone with a cooping saw. Then I glued the two halves together with white glue and some of the card board in the joint. I did this to help wick the moisture away from the glue as the Styrofoam won't let water through. I added a ring of tubing that can fit into the body tube to the base of the nose cone.

To end the first evening of this project I smeared some wood filler on the nose cone core to start building up the thickness so I will able to sand to the final shape later. It will take some time to complete shaping the cone. Cost so far <$1.00 for glue & filler.

Today I smeared some more wood filler on the nose cone and sanded the body tube using about 300 grit sand paper.

While the filler was drying I started to work on the shock mount. This I did in classic Estes style by folding and gluing the 1/8" elastic strip into a piece of typing paper. While still damp I glued the S.M. into the body about 2" down inside the top of the body tube. The paper will give the glue a lot of area to adhere to, making it able to with stand up to a 10 "G" load. It will get this abuse if the chute opens later then expected while falling at 90 m.p.h. after the boost and coast phases have run out.

The shock cord should be 2 times the length of the body tube. This will keep the nose cone from hitting the rocket and causing damage to either one, when the ejection charge deploys.

Again I smeared some more wood filler on the nose cone and glue on the body tube (as a sealer), then set them back to dry.

I cut some heavy poster board fins with an exato knife and strait edge. I glue 2 layers together to get the right stiffness. Next I used a piece of corner protector molding with a notch cut in it as an alignment guide to hold the fins while they dried. Cost so far about $1.00 for glue, filler, and 1/8" elastic strip.

So far so good. Now its time to put some beauty onto this little rocket. After reglueing the fins to make sure they won't fall off. I started to build up the fillets on the fins. These are small amounts of smoothed wood filler at the base of fin. The importance of the fillets is that they allow a for a laminar air flow around the fin base were if not present a high amount of drag would be created. This drag would be due to the sharp angles at the fin to body joint.

Now for some power. The need for correct alignment of the motor mount is my next concern. The only way to have centering rings to fit this odd size of B.T. is to make them myself. Using a compass and exacto knife seems like a hard way to do this but it's the best I have at hand.

The motor mount in this model is a 19mm ID tube about 2" long.

I cut 3 pieces of the left over fin material in doughnut shapes with a inside diameter of 20mm. and a 28mm. outside diameter. I then glued 2 of this centering rings together giving me a 4 layer and a 2 layer set of centering rings. Glue the C.R.s to the M.M. tube so that about " sticks out of the thicker (lower) C.R. and " sticks out upper C.R..

OOPS! Well I told you that this was to be my daughter's rocket. She wanted to keep it in her room while the different layers of filler were drying. You can guess what happened next. The damage is not as bad as it could have been, just one fin was broken off the body tube. So, I had to back track and glue on a new fin, luckily I had keep a copy of it.

I should tell you that I am not going to be using a launch lug on any of my scratch built models. Instead I will be using a tower to launch them with. This is a group of 3 or 4 rods (for 3 or 4 finned rockets) set so that they loosely hold the body tube at launch, thus eliminating the need of a lug with its unappealing appearance and added drag.

Now to move forward in the finishing of the model. Most of you are aware of what it takes to do a good job of spray painting some thing, so I won't say any thing other then that for the most part these are small projects and don't take a lot of time to get them right.

Graphics are the last things that I do before applying a clear coat to these rockets. Some builders like to wax and polish there ships.

I lost track of the cost of this rocket but estimate it to be less then $6.00 most of that in the paint. At $2 to $3 a can and most other stuff free or only a small amount of a sundry items like glue and filler. As you can see that this can be an inexpensive hobby, that all the famly can enjoy.

Your Questions Answered Here

Contact me jshearer@iastaste.edu

Q. Are you going to chase crows with those?

A. I hadn't planed to, but it sounds like fun.

Q. So you like to blow things up.

A. In this hobby we try very hard not to blow things up. If a hobby starts to even look like it is going to endanger the public or any property, the powers that be will shut it down. As in the case of hand guns, but I won't get into a political debate here.