The AMA Racer

A simple aircraft which serves as a great starting point to the hobby.

The AMA racer, and it's sibling the AMA Delta Dart, are simple aircraft which can be purchased in nearly any hobby store for about $3.00. They are built by gluing the supplied wood strips directly to the plan sheet. You then cut around the pieces with a sharp knife and glue them together. These planes fly pretty well if you build them per the directions. But with just a couple of modifications they fly awesome.
You have to build them straight so that they track through the air well and glide nicely. You also have to power them with a rubber motor capable of running for more that 10 seconds.
One design flaw that I noticed (even as a complete novice builder)is that the rubber is too close to the motor stick. It beats the crap out of the rubber, putting nicks in it which shortens it's life dramatically, and it vibrates the plane as it flies. My solution was to move the rear anchor point of the rubber down from the stick to gain clearance. I've since seen a couple of methods of doing this. One is like my method, and that was to build a small triangle from balsa stock and mount the pin to it. The other one I must credit to Don Ross (who I'll give full credit to shortly), and that is to cut away the lower half of the motor stick, back from the nose (it must be full depth so that the prop hanger still fits). This method is better because the motor is lined up better with the prop hook at the front. My newest one uses a combination of both methods.

The greatest education in freeflight that can be obtained (short of a brain transplant) is to read "Rubber Powered Model Airplanes" by Don Ross. Available from Carstens Publications for $14.95 plus s&h (1-800-474-6995, or PO box 700, Newton, NJ 07860). It is full of great information, including an entire chapter on modifications for the AMA Racer. By all means read the book, as it contains much more information than I am capable of putting on my web page. Carstens also puts out the greatest magazine for the free flighter called Flying Models. Ads for most of the cottage industries that support free flight are in there.

When building the AMA Racer, take your time getting all the glue joints right. The other two critical items of construction are gluing the wing halves to the stick which carries the wing, and setting the proper angle when gluing the tail assembly to the motor stick. Don't be tempted to glue the wings directly to the motor stick. Holding them on with the supplied rubber bands allows the wing to be moved for proper trimming, and it allows some flexibility in a crash.
As for the power phase, here is a quick lesson in rubber power. It is hack science in comparison to the rituals that "real" free flighters use, but it will get you in the air. All forms of rubber that I have seen come with a powder called talc on it. It keeps the rubber from becoming a sticky mess during storage. Since most rubber strip is used for such mundane tasks as holding a newspaper rolled up, or shooting at your little brother, it serves it's purpose well. But talc is an abrasive, and it is definitely not a friend of the free flighter. The stuff washes off easily with dish soap and water. Next, the rubber must be lubricated for it to hold all the turns that we want it to. Cheap and dirty is to just grab some Armor All, or STP Son of A Gun silicone. I put the rubber in a sandwich bag with just a little bit of the stuff and get it soaking wet. Let most of it drip off somewhere and it's ready to go. Better yet is the use of silicone grease (there are many automotive and home improvement uses of various forms of the stuff), but the runny stuff will work well for an introduction.
Without the lubrication step your rubber will only last a few flights, and an attempt to max the rubber out will have the talc cutting through, causing it to burst. With lubrication the rubber will last at least 20 flights, and it will take a shocking amount of turns. This is where the long duration motor run gets your nice flying plane way up there.
I suggest that you obtain some good extra rubber. You can obtain some 3/32" Tan II from HSS (check the links at the bottom of the first page, or Peck, or Sig (make sure the stuff you get is tan and not black), or the master source of the stuff: FAI. Use the rubber that came with the kit until the new stuff shows up. Wash and lubricate it as directed above and it will happily take 500 turns or better. For intitial test flights I highly recommend you start out with 100 turns. Work your way up in 25-50 turn increments as it demonstrates good flying qualities. You'll need some pretty serious room to wind it all the way up.
To wind it up all the way you will need to obtain a winder (a geared device that makes winding much faster, available for about $10). You'll also need to learn the technique of "stretch winding". This involves having a trusted person (or a device called a stooge) hold your plane. You then stretch the motor out to 3-4 times it's relaxed length and begin winding. Once you get about half the turns in, you begin walking towards the airplane. In the case of the AMA racer, the plane has no "winder loop" on the propeller end. You can get around this by removing the motor from the rear peg, and having your friend hold the plane by the prop and prop hanger up front. When you arrive at the plane after winding, you remove it from the winder and loop it back on to the rear hook. Planes with enclosed rubber generally have a loop on the prop hook.
If you want to know what a motor will really take, you need to do a little test. I am in the habit of tying up three motors for a new plane. I hook one of them up to something in my house and stretch wind it until it explodes, keeping track of the number of turns at that moment. I then calculate 80% of that number and use it as the maximum number of turns to use for flying. That number is valid for motors of the same size and length from that batch of rubber. If you get more rubber strip, then do the test again.

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