By Bob Fortune, LUNAR #660
Flying rockets, when done properly, is very similar to throwing a boomerang. The trick is often getting the thing to come back. The following is some of the failure-to-return modes a rocket can experience in its lifetime.
Rocket-Eating Trees
Trees are a positive force in nature, right? A positive force surely must mean having a positive charge. Rockets are somehow attracted to trees. Therefore rockets must be negatively charged otherwise so many of them wouldn't end up co-habitating with the squirrels. There are a couple of things that the rocketeer might do to prevent this attraction from occurring though they might look a bit silly taking the necessary steps out at the pad.
Briskly rubbing the rocket with piece of rabbit skin will not only impart a charge to the rocket but also might bring it good luck. One ends up with a positively charged rocket to counteract a positively charged tree. The rocket most likely will do a button hook about the tree and head for the landing zone. Something else that might work is polishing the rocket with a "Bounce" dryer sheet. This removes all static charges, positive or negative, so that the rocket will neither be drawn to the tree nor repelled by it. Do not put this in your rocket when you are done wiping it down as it might counteract the smell of black powder and make it appealing to the powers that be. See the rule below about beautiful rockets. Rather, stuff the used sheet in your pocket so that you can smell spring time fresh all day long. Lord knows most launches could stand it given the plethora of engineering-types who fly rockets.
Beautiful Rockets
The rocket gods are known for their delicate taste in rockets. The ugly ones they toss back keeping the most nicely finished rockets for their vast collections. The trick here is to make the ugliest possible rocket that will not only be unsightly in their eyes yet still get past the RSO . This is a diametric opposition, of course. RSOs like pretty rockets and encourage you to fly them as they know pretty rockets are often well-made, carefully prepared, and will generally enjoy a nominal flight profile. The rocket gods also like pretty rockets and often don't give them back. Maybe the RSOs are in cahoots with the rocket gods, sure seems pretty suspicious to me.
Building rockets out of Pringles cans or paper towel tubing is one way of getting your rocket back in one piece - it's ugly to begin with. Cut fins using scissors from corrugated cardboard,make sure you use lots of black electricians tape and hot melt glue to hold them in place, then paint it with one coat of red enamel so it looks real fuzzy.
Minimum Diameter Airframes, Energetic Motors, and Indiscretion
This often involves a QuEstes rocket and a motor not even remotely mentioned in the instructions. For example, when was the last time you saw Apogee D10-7 as a possible motor selection for an Quest Sprint. Or an Aerotech G125-10 mentioned on the Estes Maniac packaging? Big Bertha on an H123? Fat Boy with an I65 installed? Here's where the rule of thumb "The motor is always the same diameter as the airframe" kicks in. "More power" also works. The trick is to use a single use motor and never sacrifice a reloadable case, especially if the rocket is even slightly appealing to the eye. As the rocket disappears over the horizon one can only hope that the recovery system deploys as intended. The lucky rocketeer is usually rewarded with "Did anyone see where that thing went" coming over the PA system.
Mach Busters
Purchase a "Mach Buster" from Impulse Aerospace and install the largest recommended G motor. Make sure you close your eyes so you can concentrate on hearing the sonic boom. Just like magic the rocket will be gone when you open your eyes again.
Big Parachutes
The rule of thumb in choosing a parachute is "Too much is not enough" though "Small is good" also works. It's a somewhat gray and mystical area, a bit arcane and only the juju of the rocketeer decides how a rocket will return on its chute. Selecting a canopy made from virgin nylon sewn by virgin seamstresses seems to work the best for me. Since parachutes most often come in sizes that increase in 6" increments stepping up from one chute size to the next can have surprising results. This is called "hang time".
Often there are globular bubbles of heat around launch sites. They are formed when the sun heats the ground in one particular area like a street or parking lot. A kid on a bicycle riding through this warm zone often sets it free as a column of warm, rising air or thermal. Of course, rockets can be attracted to this column of air and gravitate towards it. This is called "thermaling", "flying away", or "Did anyone see where that thing went".
How To Build a Rocket That is Guaranteed Not To Come Back
Find something that fits the largest motor in your inventory. Let's say you have a G80 in your range box. Well, heck, this fits nicely in any BT-56 rocket with a sleeve of 29mm motor mount tube installed. Spend the next few weeks building the rocket, fillet the fins, sand it with grit up to and including 1000. Install 3 coats of primer and 3 coats of finish, sanding between coats of course. Add time intensive graphics as required and forget to include a name or telephone number. It's important that the rocket look perfect, I can't stress this enough, and make sure that there is at least 8 to 12 hours of your time in the building and painting process.
Next, select the largest parachute that will easily deploy from the airframe, say a gauzy 36" canopy that you've had for years with nary a scorch on it. Install motor and parachute with recovery harness in the rocket and check to make sure the center of pressure jives with the center of gravity. Install noseweight as required to bring Cp mojo and Gg mojo into alignment with the universe.
Wax the rocket several times, this is important. Also powder the parachute and forget to include a tracking charge.
On launch day show the rocket to the RSO and when he asks if it's ever flown before laugh and say "You're holding it in your hands aren't you?" Install the rocket on the pad, wait for the countdown and say your goodbyes. You will know you've done your job properly when the LCO asks the crowd "Did anyone see where that thing went?"