FREE FLIGHT INDOOR
Bud Tenny, Box 830545, Richardson TX 75083
END OF HOUR-LONG FLIGHTS?
After the Marines moved out of Tustin, the two hangars are being leased. First to go was the second hangar, but the one used for Indoor is expected to be next. The hangars seem to be viewed as excellent locations for movie sets.
The International E-Mail A-6 Indoor Contest: This landmark event is getting a lot of activity, with raw flight times posted on the Internet. Before the contest finishes (March 31, 1998) the raw times will be adjusted according to ceiling heights to produce final scores. Sample raw scores (time/ceiling height): 4:45/225; 5:05/265.
If you are competing, check out Del Ogren's Web site: www.nlemmacom/indoor. While you are browsing, also check out www.ultranet.com/davison/indoor.html. Glenn has revamped and expanded his site; there is a tremendous amount of Indoor information there.
FID SURVEY
A previous column discussed transporting Indoor models safely. Part of the discussions triggered by Richard Doig's comments included reducing span to 55 cm, to minimize box sizes for a better fit in current airline overhead bins. There has also been concern about a looming shortage of microfilm, which could lead to outlawing microfilm on FID models.
A survey of FID fliers followed, with these results:
- Most of the fliers reported having enough microfilm to last for at least one World Championships cycle.
- Only 43% of the group were in favor of outlawing microfilm for FID.
- Fifty-seven percent of the fliers favored a span reduction to 55 cm; only 24% favored a total area limit if the model specs were changed.
- None of the fliers favored a rubber weight limit.
TAN II REPORT
The 7/97 vintage Tan II has been supplemented by 10/97, which is very similar in most aspects. Larry Coslick tested 7/97, 10/97, and 8/93 against each other, using a very practical approach. Excerpted from Larry's report in Indoor News and Views:
Larry stripped rubber to weight from all three batches, and made 1/4 motors 3.5 inches long and weighing 0.26 g, accurate to within one percent. His test model was an Easy B that weighed 0.9 g. Each motor was prewound to 0.15 inch-ounces of torque and unwound twice. All test flights were made in a two-hour period at 72°F, 45% humidity, and less-than-perfect air.
Winding for launch was to 0.3 inch-ounces, then backed down to 0.15. This resulted in approximately the same number of turns for each launch.
The results from successive flights:
- 8/93: 4:48, 4:53, 4:56.
- 7/97: 5:20, 5:18, 5:28.
- 10/97: 5:11, 5:05, 5:14.
Larry observed that 10/97 sags momentarily during the climb, but that 7/97 keeps plugging. Also, 10/97 takes more abuse, but will grapevine if you come in too fast.
The earlier report in the column also mentioned that the 7/97 batch was sold out before any Indoor fliers heard about it. According to FAI Model Supply, the shipment arrived just before the outdoor WCh started, and most of it sold immediately.
INDOOR GROUP
The Indoor Group now has more than 130 members. Join us by sending your request to Bud Tenny at rten@nstarnet. Note: This is a change in address; by the time this issue arrives the previous address will be phased out. Current members, please update your address lists.
FLAT AIRFOIL?
Jim Clem's continual experimentation has panned out again. He built a new version of his Cobra MiniStick, which used a wing and stab very similar to Andy Tagliafico's record holder. The difference is that the airfoil has no camber (Figure 1).
Note the sharpened leading edge and the extra-deep rear spar. This extra depth has been referred to as a "kicker" or "Blubaugh Fence," and was discussed in Indoor News and Views several years ago after being suggested by Hal Blubaugh. The amount of extra depth is subject to experimentation, often with very interesting results. The new configuration seems to climb faster, and handles torque more easily. Quarter-motor flights in Jim's high-ceiling living room are longer than with conventional airfoils.
INDOOR GLUE
(From The Thumb Print, newsletter of the Thermal Thumbers of Metro Atlanta, edited by David Mills.)
If you want to make satisfactory Indoor cement, thin Sig-Ment or Ambroid 50/50 with dope thinner or lacquer thinner. Apply the glue to joints with the tip of a needle. If you can see dried cement in the joint after construction, you used too much cement. Make good joints; use minimal cement!
The flight time between a model weighing 0.015 g more than a twin can be substantial. Picking good wood cannot offset use of too much cement. Cement is heavy. Cyanoacrylate (CyA) glue is heavy, too; don't use it for Indoor models. If you need to change trim, a quick application of thinner to the joint will allow you to reconfigure a cellulose-cemented joint. CyA joints are very difficult to change. Consider the difference when you choose an Indoor adhesive.
CUSTOM SPARS
Making custom spars, such as 0.030 x 0.025, is easy. Pick up a couple strips of 0.025 brass from the K&S display at your favorite hobby shop. Using double-stick tape, stick the two brass strips beside each other on your Formica shelf board with a gap of 0.030 in between. Cut a 1/32 x 1/16 strip from your favorite sheet of five-pound balsa. Place the spar between the two strips of brass and press down firmly against the sticky tape. Presto! You are now ready to sand with a block of 320 Wet-or-Dry paper. You can use double-stick tape to attach the sandpaper to the block. Works great! Sand in one direction, away from the core strip until you begin to sand the brass strip. Carefully remove the sanded spar from between the brass strips, and there it is — a perfect spar to the dimensions you need.
Since the brass strip comes in many thicknesses, you can custom-sand to any dimensions you want. If you want to taper the spar like the experts do, shim one end with another thickness of double-stick tape. One layer is approximately 0.020 thick, so two layers of tape at one end of the strips will give 0.040 taper to the spar.
NFFS DIGEST TIP
From NFFS Digest: What do you do when your CyA glue has been sitting around for a while and is getting too thick? If it is the thick type, and you don't have too much left in the bottle, you can add some thin CyA to it to thin it out enough so that you can finish the bottle. The late Bob Hunter from Satellite City, the makers of Hot Stuff, gave me this tip: keep the glue in the freezer until you are ready to use it for the first time; this will increase its shelf life. Let it come up to room temperature before you use it. (By Terry Thorkildsen)
EXPERIMENTAL RUBBER TEST
A photo shows an idea for a rubber-test fixture I am trying. The test motor drives paddle blades instead of a prop. During motor run-down, the rpm will be recorded vs. time.
Design features:
- The paddle blades are interchangeable, to accommodate different rubber sizes. The paddle size is chosen to give a run-down rpm close to that expected if the motor was flying a model.
- The distance between hooks is adjustable to accommodate differing motor lengths, and to document changes in power output from differing amounts of slack. I expect to run the first set of each series with hook spacing equal to the starting length of the motor.
This test rig gives several opportunities:
- To make meaningful comparisons between different batches of rubber by using a standardized loop length and weight.
- To directly test new motors, then attempt to correlate test results with flight results. If I get good correlation, the test results should ease the process for selecting motors at contests.
- Research the "rubber gets tired" theory. I've always felt this theory stems from stretching rubber; I can change the hook length to remove the effect of stretch. Jim O'Reilly's discussion in the 1993 NFFS Symposium has already laid the groundwork for such a test, showing that rubber gets better, not tired, with repeated usage. The only caveat, of course, is that rubber is altered mechanically or chemically by damage.
Transcribed from original scans by AI. Minor OCR errors may remain.
