HINTS ON USING THE TEXAS MICRO I TIMER
Several questions have come up about how to best take advantage of the Texas Timers MICRO I timer. This will try to address all the questions. Topics covered will be:
* What kind of airplanes can use it?
* Using the timer
* How is the timer calibrated for a given engine run time?
* How is run time repeatability achieved from flight to flight?
WHAT TYPE OF PLANES ARE SUITABLE FOR THE MICRO I?
This is a very good question. Initially, the timer was designed for use in the highly weight conscious 0.020 engine planes, where 6 grams would be very attractive. It was not known how the timer would behave in larger applications. From the very beginning modelers started using it in larger 1/2A planes, and at the 2000 NATS , a plane won F1J using a hot Russian .060 and the MICRO I. One customer has over 1000 documented flights on his MICRO with a PET .090 engine - without a single problem or failure. We did see a few problems early one with much larger engines usage. The problem was not a larger engine, but the fact that they do not run at the very high RPMs of the smaller engines. We found that a harmonic self-resonance occurred with the start wire in the 14,000 RPM region. The start wire was literally shaking itself to pieces with vibration. A design change was made in the start wire to reduce this failure mode, and since then, the only problem we know of is one flier who is using a McCoy .35 and occasionally seeing a broken start wire. Otherwise, the timer does not seem to care what the engine size is.
This model is the most accurate and repeatable mechanical free flight timer we have ever seen. The high speed of the clock (about 3 seconds per revolution) makes it possible to set times very accurately, and get dead on repeatability flight after flight.
There does not seem to be any problem with the clock mechanism, timer construction, or timer accuracy associated with use on any kind of plane or with any size of engine.
When used with any good high quality thin-wall 1/8" latex fuel line, pinch off is definite and positive, even when using high bladder pressure. Of course, we do suggest our super good fuel line in the Small (1/8" OD) size. Not only is it very soft, it is totally impervious to nitro, sun light or long term storage. It literally lasts forever, unlike latex. We do not recommend using our x-small size fuel line as it may be too small in some cases.
USING THE MICRO I TIMER
There are three key things to remember
* Always start with the scroll fully wound finger tight. Do not force it, just wind it snug with your fingers. The scroll is not designed to slip on the shaft.
* Always put the wire in the same groove of the scroll.
* Always launch with the red mark on the disk at the same place on the dial.
WHAT ABOUT OTHER USES?
We keep being amazed at the cleverness of our customers. Gil Morris published a way to run an auto rudder with a MICRO in the 2000 NFFS Symposium, and Joel Schwartzman published a way to use it for quick DT in the September 2001 NFFS Free Flight Digest. Joel's method is to make a loop out of some slippery line like mono filament fish line, and put the loop over the scroll in the first thread below the engine trip wire. This gives a DT delay of about 3 seconds. Who knows what unpublished applications there are?
CALIBRATION
The whole process is very easy if you follow these simple steps.
1. Cock the mouse trap mechanism.
2. Put the stop wire in the hole to keep the clock from running.
3. Wind the scroll in a clockwise direction until it is finger tight (snug). Do not use any tools for winding. The scroll is not meant to slip. It is very tightly held to the spring shaft.
4. Pick some groove in the scroll and put the wire in it. Lets say the third groove down from the top. Pick some point on the timer face dial as an arbitrary time start point. The point needs to be someplace counterclockwise from the red mark on the disk. Lets say the red mark is at 3:00 O'clock. Pick 9:00 O'clock as the start point for engine run time.
5. Get your watch ready to start and trip the start wire on the timer. Start your watch when the red mark on the disk exactly passes the 9:00 point.
6. Stop your watch when the wire running in the scroll snaps out. This will be a very noticeable snap. Now, how does the time on your watch compare to the engine run time you want?
7. If it more than three seconds too fast, then repeat Steps 1-6 with the wire in the scroll one groove lower for every whole 3 seconds you were fast. Ignore fractions of 3 seconds. For 5 seconds, just move down one full groove.
If it is less than 3 seconds too fast, then repeat Steps 1-6 with the wire in the same scroll thread, but this time start your watch when the red mark is more counterclockwise. Say 3:00. You should be within 1.5 seconds or so, now. Get the idea? Just move your start point on the dial clockwise or counterclockwise until you are right on the desired time.
8. If it is more than three seconds too slow, then move the wire in the scroll higher, following the same rules as Step 7. Follow the same procedure as Step 7 if your time is less than 3 seconds too slow.
9. Put a pencil mark on the faceplate dial at the point where the red mark is when the run time is just what you want. You will need to remember how many grooves or threads down from the top to place the wire. If you have some fly off times, determine the settings for it too, following the same procedure described before.
THAT'S ALL THERE IS TO IT!
RUNTIME REPEATABILITY
As with anything on your model, always check the engine kill with the engine running. Have a friend measure the time. Any tweaking needed should be very minor, or none at all. Adjust the mark on your faceplate as required. From here on it is all easy.
1. Always start with the scroll fully wound, finger tight.
2. Be sure you put the wire in the correct scroll thread or groove.
3. Light your fuse or start your DT timer
4. Start the timer
5. Launch when the red mark is at the correct point (already marked) on your faceplate.
There are variations to this to suit individual modelers. For example, some like to set the red mark on some set point, and then follow a fast "trip the timer and launch sequence."
You should expect and receive outstanding performance from the MICRO I timer.
If you encounter any problems or have difficulties, please contact us and we will do our best to ensure you have complete satisfaction with this timer. Let us know if you find more uses or have ideas for new products. We are always listening. Talk to Hank
THERMALS AND GOOD FLYING - TEXAS TIMERS