CETO notes: Cloud Nine RC 3/1/95
a. The control actuator is probably best located somewhere between the wing and tail of a conventional design model; with a pull/push rod to the rudder of eight inches or less in length. More than that length makes the weight of the rod a bigger factor, which acts against the marginal power of the actuator. Also, longer length requires a stiffer rod to avoid "lost motion" due to bending, and more stiffness usually means more weight.
b. The best length to weight ratio, accompanied by adequate stiffness, seems to be achieved with a small diameter (.020"-.028") music wire pull/push rod of six inches or less. Trying to use a small cross-section (1/16" sq.) balsa rod, with wire ends results in more weight than the simple wire rod. But, if a balsa rod is used, it can be stiffened easily by a light coating of CA glue.
c. Push/pull thread or cord and pulley actuation systems tend to be more critical in adjustment over small distances, with friction more difficult to avoid. Correct thread/cord tension tends to be more difficult to get "right", except for skilled rubber powered indoor model fliers who usually have more experience with delicate adjustments.
d. The Ceto connectors are somewhat fragile. The one that gets the most use is the one that plugs in or is pulled apart for hooking up the charging cable between the transmitter and the receiver batteries. If your system quits working, a likely problem source is the male plug from the receiver that plugs into the receiver battery cable. If the insulation is carefully slid back on that male plug, it may be that one or both wires have broken connections: carefully resolder to restore operation.
e. A very practical "packaging" may be a good idea: tape the receiver and battery components together, along with the on-off switch. This results in one neat little component that may be easily slid in and out of a simple balsa box in the model. Such a package also results in a lot of excess wiring that can be taped down as part of the package-or the excess wiring can be cut off (and the short ends soldered together) to save weight and make the package even more compact.
f. The switch is "on" when the switch peg is in line with the wires connected to the switch. To avoid confusion about which position is on or off, when the switch is in the model (where the wire connections to the switch may not be seen) a dab of red paint or red fingernail polish at the "on" end of the switch may be helpful.
g. Somewhat larger rudders than recommended by CETO are okay, if carefully pivoted and linked to the actuator, to avoid excess friction. The simplest and lightest friction-free hinge, to me, is the Figure Eight thread system made popular for many years by Controline fliers. Actually, about twice the recommended size rudder is feasible (about 1 1/2 square inches of rudder surface), preferably of high aspect ratio (say 2 1/4"high and 1/2" wide, or 2 3/4" high and 3/8" wide). In any case, about 45 degrees of total rudder deflection is desired.
h. I'm currently working on (in addition to various pulse systems) a slightly heavier but more versatile control system. Two channels are involved; one for operating a conventional proportional and non-pulsing micro servo for the rudder and the other operating a subminiature smooth proportional speed control for electric motor powered flight. A conventional single or two-stick transmitter is used. Airborne weight of the 2-channel control system is currently about 2 ounces. This system is sort of between the CETO and Cannon control systems; probably best suited to 30" or three-foot span models, with the ability to be flown in gentle winds. Cost may be comparable to the CETO system. The CETO is relatively high priced because of a relatively low production rate and dollar devaluation for European products. More on the 2 channel system in the near future.
i. A neat model I'm building (with Bill Poythress' help) is a quarter scale (27" wingspan) version of Chet Lanzo's 1937 Nationals RC Event winner. The original (nine-foot wingspan) was rudder-only, using a small electric motor to wag the rudder back and forth. The control signal stopped the motor at random positions, so the piloted "beeped" the rudder signal and watched the model reaction to find a suitable position!
The CETO magnetic actuator provides a superior system: no signal has the rudder in one extreme position, for which the model is trimmed to fly in a gentle circle in one direction. Holding the transmitter button "on" obtains the opposite extreme rudder position, for which the model is trimmed to circle in the opposite direction. Manually pulsing the transmitter button on and off causes the actuator to assume an average position between the two extremes; either neutral for straight flight or some other average position less than full throw for a partial rudder average position.
The Lanzo design is of open crutch fuselage
construction, so all components are easily seen and adjusted. The
electric motor is a Hi-Line, direct-driving a 4 1/4" plastic prop, via
three 110-mah Sanyo batteries. I expect it to be fine indoors or
outdoors, although the indoor site should be larger than a basketball court.
Till next time, have fun!
CETO RC CLUB NEWSLETTER NO.2 May 25,1995
The micro-miniature world of RC continues to be full of fun and surprises. One recent experience was of the Good News-Bad News variety:
My 27" wingspan, two and a half ounce total weight, electric powered, quarter scale version of Chet Lanzo's 1937 Nats RC event winner flew beautifully. The problem is that it flew away! It was built for Indoor, but I flew it outdoors. Big Mistake!
At 2 1/2 ounces it was almost instant thermal fodder. The motor, driven by three 110 mah nicad cells, ran for over two minutes. It went up and away. I could steer it, but there was a breeze about a hundred feet up (not noticeable on the ground) that in combination with a thermal sucked the model over the trees, never to be seen again.
Warning: a model that light is too risky to be flown outdoors on a warm sunny day. I doubt that a dethermalizer would have brought the Lanzo model down. Besides being light it had a lot of wing area-- good for Indoor, but not outside.
So, I went back to the workbench and my 2 ounce half size 1951 RC design, with C02 power. At the request of several other CETO owners I said I would see what could be done to improve the single transmitter button control system. After a few nights of experimentation, I came up with a tiny pulser circuit that fit in the transmitter case.
Then I added a small on-off switch and another push button switch. I hooked the circuitry up to the existing transmitter battery. Now what I have is a transmitter signal that pulses when I turn the new circuit on, so the rudder on the model flaps back and forth about twice a second for an effectively neutral control position.
Then, when I push the original transmitter control switch, the rudder holds in the full left position and when I push the new push button switch the rudder holds in the full right position.
It works great, the parts are few and cheap, and the system is much less confusing for people who find it hard to use the original single button CETO control switch. I hope to have an article on this published in one of the magazines and I may offer a kit of parts for anyone to modify their own transmittr in the same manner. (Ed. Note: There is a newer version in a later Cld9 newsletter)
The project was fun and was like the old days of benchwork to improve control systems-- as we often did in the 50s when we wanted something better than an escapement to fly with.
I am also installing a new control system in a little floater that Frank Ehling built. It will be two channel, usinq the Hi-Tech (originally RCD) "Shredder" receiver on 27 Mhz. It has a Cannon micro servo for proportional rudder control and a tiny motor speed control that is also proportional. The weight will probably come out a bit heavy (about 4 oz.) but I think it will be okay in a bigger Indoor site (something more than a single basketball court. More on this later.
I have a neat little very powerful magnetic actuator for the CETO system, made from a very small motor from a small servo. But it has a relatively high current drain, so I'm looking for another small servo motor with less drain. If I find the right one it could be the answer to replacing the CETO actuator with one having more throw and more power.
There's a guy on the west coast, name is
Bearl Duddles, who has put out an advertising flyer on his micro receiver
and servo. Receiver is 7 grams, servo is 6. They are supposed to
work with conventional transmitters, but his price is $200.00
(Postal money orders only) for EACH! He also says to allow 90 days for delivery! I'm leery until I know more.
I hear too that Dave Abbe (DAD RC equipment) will shortly have what he calls a "naked" receiver, small and lightweight, for use with conventional transmitters and micro servos like Cannon's. Price is also expected to be reasonable.
I'm optimistic that within a few months Cloud Nine RC will be able to offer a 2 channel receiver, a micro electric speed control, and a Cannon type micro servo for a total of about $100. This may well prove to be the most practical system for Indoor RC.
In the meantime, the CETO is still a neat and super-light system that is fine for single channel, if you master the delicate control linkage to operate the ruddur. One other developement that is being looked at for the CETO is a two control RudderVator that would add about a half ounce to the system, but would provide full throw rudder and elevator control (one at a time in sequence, sort of like the old escapement controls).
All in all, a lot is happening and much of it is like the 50s in RC, when new developments popped up on an almost weekly basis.
Sure would like to hear what anyone else
is doinq in the micro-miniature RC field. How about some letters or phone
calls, or a Fax?
CETO CLUB NEWSLETTER NO.3 JULY 1, 1995
This newsletter is an informal means of communicating information about the micro-miniature CETO RC equipment in particular, and micro-miniature RC equipment in general. The intended audience for this newsletter is primarily those who have purchased the CETO equipment, but also goes to selected individuals who have shown a special interest in micro-miniature activity.
There is no specific charge for this newsletter, but what would help to enable issues to be produced more often and perhaps with more pages per issue are some donations of $ 1, $ 5, or whatever, to defray the cost of postage.
1. Maintaining equipment reliability. As with all RC equipment, battery voltage (and capacity) is the key. It is important, therefore, to check the CETO receiver battery regularly. It is much easier to do with the transmitter because there is a battery condition light that tells, by color, whether the battery is ok. Incidentally, after much use in the CETO, I recommend using alkaline batteries for the transmitter-- they last much longer than a typical AA NiCad battery charge. In fact, I have yet to replace my transmitter alkalines, despite hours of bench and flight use. Their use eliminates the need and bother of transmitter battery charging.
The receiver/actuator battery situation is more
complicated. The NiCads are the lowest weight power source (although I'm
optimistic about coming up with an equivalent weight alkaline battery source).
Initially, simply following the CETO charging information works fine: charge
overnight by plugging into the
But, sooner or later, the very small capacity of the receiver actuator power pack results in concern as to whether the cells are at full charge. This means that a voltmeter or some other form of voltage indicator is needed, to test whether the power pack is up to full voltage. This test should be done with the transmitter signal full on and the actuator in the full on position.
For me this means that the voltage should be no less than 3.9V. That's 1.3 volts per cell, under load. Some modelers go with 1.2 volts per cell, or 3.6 total. For a short flight (about 2 minutes) that may be okay, but I like a little more margin. In any case the test means being able to get at the battery pack and in some small model installations that may not be easy.
Because being able to measure the voltage regularly is important, I think it is worth bringing extra wires out from the plus and minus ends of the battery case so that the wire ends are available on the outside of the model for voltage testing. This is well worth a little initial extra work to make checking (and assurance of reliability) much easier.
Equally important, to me, is being able to check the charging current coming from the transmitter battery pack to the receiver/actuator battery pack, via the CETO supplied charging cable. I have found it desirable to cut one of the charging wires about mid-length (either the plus or minus wire, although I prefer the minus). I strip about 1/8" of insulation from each of the cut ends, then I tin those ends with solder. Next I solder a small (the smaller the better) alligator clip to one of the cut ends.
When not checking the charge rate, the alligator
clip wire end is attached to the other wire end. To check the charge
rate, the alligator clip is connected to one end of the milliampmeter to
be used for checking. Then another
piece of wire is used to connect the other end of the meter to the other end of the charge cable wire.
What's important here is to connect the meter correctly: the plus of the meter to the plus end of the charging cable wire. Note that the plus here is that of the transmitter battery, not that of the receiver/actuator battery.
The normal charge rate is very low compared to larger conventional radios. Remember that the receiver/actuator cells supplied with the CETO are only rated at 30 mah (milliamps per hour). Thus the charge rate should be only about 1/10 of that-- 3 to 5 milliamps! That's almost nothing, compared to conventional battery packs, which typically use cells of 100 mah or more. That, plus the fact that the CETO uses only three cells in the model, instead of the usual four, means that it is very easy to overcharge the 30 mah cells unless we are careful provide only as much charge as needed.
Basic rule: if you charge at a higher rate than is normally supplied via the CETO charging cable between the transmitter and the receiver/actuator, the charging time has to be reduced. How much is directly related to experience with the charging process. Instead of the 10 hours or more normally required, it is possible (though not recommended unless you really know what you're doing) to charge for only minutes instead of hours.
Regardless, the key point is to know what charge rates and voltages you are dealing with. The goal should be to know the condition of your battery pack. One end of the problem is easy to tell: when the pack is weak, the actuator has no snappy or crisp action, or doesn't move at all-- the latter usually means the receiver is also not operating.
At the other end of the problem, it's usually a matter of how long proper operation will last. A full charge is typically good for about an hour of intermittent on and off operation.
2. More Receiver/Actuator Voltage? During some bench checks, when the regular CETO receiver/actuator battery pack needed charging, I disconnected that pack and connected a pack of four 50-mah Sanyo NiCad cells instead. This provided a voltage about 4.8 instead of the usual 3.6 or so. This combination worked well and gave the actuator a little snappier action--the extra voltage helped provide a little more actuator power, which on 3 cells was marginal.
I haven't tried the 4-cell pack on a receiver range check and haven't flown with it yet, but I think it should be fine. In addition to the higher voltage, the 50 mah cells will last longer. The weight penalty is about 8 grams, or just over a quarter ounce; tolerable for most applications. So the all-up airborne weight is now 22oz. instead of 14 ounces; just over 3/4 of an ounce total, instead of a total of 1/2 ounce.
3. A Relay instead of the Actuator?
While playing with the 4-cell setup, I remembered that I had a tiny PC
(Printed Circuit) relay rated at 5 volts. I tried it in place of
the CETO actuator and it worked fine, following pulses of on-off operation
at about three per second without a miss. This suggested that the
relay could control a separate pulse rudder system with more actuator power,
or a "Galloping Ghost" type of pulsing Rudder and Elevator control system.
I also tried the relay on 3 cells and it worked okay, but I felt more secure with the 4 cells since they provided a voltage total closer to the 5 volt relay rating. The relay has a coil resistance of 55 ohms and operates at a current of about 90 milliamps. Its Single-Pole-Double-Throw contact points are rated at one Amp, at 125 Volts AC-- plenty for almost any RC use.
The relay weighs only two grams (!) and is less than half the size of the CETO actuator! It's rugged, enclosed in a sealed case so it is dirt proof and crash resistant; also does not require any adjustments for operation-- simply install and operate. I took one apart and it is built very well; not at all fragile.
The relay is Radio Shack's No. 275-240 and sells for only $1.99! It opens up many new possibilities for more powerful control systems for the CETO. I'm guessing that such new systems might add an ounce or two to the overall airborne system weight and this might require a slightly bigger airplane, but little outdoor models might be more practical. More on all this as the bench work develops.
4. A Transmitter Pulser? I have one installed in my CETO Transmitter. It's small, cheap and may well be further developed to provide Rudder and Elevator proportional controls. For now, though, it simply pulses the signal on and off, so the rudder waggles back and forth at about three times per second, for an effectively neutral (or straight-ahead) control position. Pushing the normal CETO transmitter control button provides full on signal for full left Rudder. An extra push button switch which I installed, provides full signal off for right Rudder. It works very well and makes flying much easier. More on this too, later, after some more testing.
5. The LANZO is back! In a previous newsletter I told how my 2-1/2 ounce electric powered quarter scale (27" instead of 9 feet) model of Chet Lanzo's 1937 RC Nats winner flew away. That was in mid April. Well, on July 3rd it was found, about a quarter mile away from where it was launched.
Apparently, after 2 1/2 months up in a tree and through a lot of rain storms, the little rubber bands holds all parts together rotted and the separate model parts came down to the ground. The model looked scroungy, with a lot of dirt from soot infested tree leafs, and the electric motor was a blob of rust. But some WD-40 spray and some hand twisting of the motor armature, plus relubrication, restored the motor (a Hi-Line 4, direct drive) to normal operation.
The dead motor and receiver/actuator batteries
came to life after charging each cell separately at about one Amp for 10
seconds and now they charge and operate normally. The only model
rework needed is a recovering of the tail assembly. Best of the CETO radio
works fine-- the receiver and actuator are sealed well enough that no water
got inside. So the Lanzo will fly again, although Indoors only!
6. On the Horizon. An American modeler has
developed a single channel (on-off, like the CETO) control system with
an airborne weight only about 3 grams! It is for Indoor models and
operates by a light beam! Using a 50-watt spotlight the model can
be operated from about 100 feet away. The light beam, when it hits a phototransistor
on the model causes a magnetic actuator (like the CETO) to go full over,
pulling the rudder over. More on this as we learn more.
From the light beam actuator has come an idea about how to increase the power of the CETO actuator. I'll advise how this works out. Otherwise, using the relay described above to connect more voltage to the CETO, more power can be obtained. It all gets down to how much weight gain may occur in the process.
Another way is to use a tiny motor (micro-servo, for example) in place of the CETO actuator. With a spring to hold the motor against a stop, when actuated the motor will drive over to another stop, then return as the signal is cut off. Or, using the spring to hold the motor in neutral, the relay is pulsed on and off to oscillate the motor; then signal on or off will cause the motor to go one way or the other. Stops to limit motor rotation to less than 180 degrees also limit the rudder.
MORE NEXT TIME
CETO CLUB NEWSLETTER NO.4 AUG.5,1995
1. Pulsing Transmitters. For those who prefer to have a more selective means of controlling rudder position, instead of the CETO system, which has the rudder at one extreme position with no signal and the full opposite position with signal on, two approaches have been very successful:
A. Pulsing the signal on and off for an effectively Neutral position, with signal on for one full rudder position and signal off for the opposite full rudder position. A simple and low cost pulser circuit is added to the transmitter, as shown elsewhere in this newsletter. Only about $10 worth of Radio Shack parts and one or two evening's work is involved in modifying the CETO transmitter; no change to the airborne control system.
B. Proportional pulsing, similar to the above, but with a variable rudder position, according to transmitter control stick position. The easy way to do this is to use an old 27 mHz transmitter, with an already built-in pulser circuit and control stick mechanism (including rudder trim). I am using an old single channel Testors transmitter, others have used old Ace transmitters--there were at least a dozen makes on the market in the 50's and many old timer RC modelers still have such transmitters laying around in their basements or attics.
All I had to do to reactivate mine was to snap in a new nine volt Alkaline battery, turn on the transmitter and receiver switches, then watch the CETO actuator waggle back and forth in response to movements of the control stick-- amazing! It doesn't seem to matter what 27 mHz frequency the old transmitter is on: the broad band super-regen type CETO receiver responds to all of them. My CETO transmitter has a 27.145 crystal; the Testors transmitter crystal is 27.195. The receiver has no crystal.
2. Separate CETO components available. (ED. Note: Call for prices and availability.)
3. New CETO Charger. For those using NiCads for CETO transmitter power, this new item may be of interest: Cost, postpaid, is $34.95. The charger operates of 12 volts: it has two parts- the basic unit plugs into a car's cigar/cigarette lighter and provides two outputs, one for the CETO transmitter and one for the CETO receiver/actuator-- simply plug in those components to the charger. The other part is an adapter which, after plugging in the charger, may be clipped directly to the car battery. A cable is provided to connect the transmitter to the charger and the regular CETO cable connects the receiver/actuator to the charger (instead of to the transmitter).
For those not using NiCads in the transmitter,
the use of alkaline batteries instead is recommended. Alkalines provide
good long-life power for the transmitter, with ample reserve to charge
the receiver/actuator batteries.
4. Problems with connectors. The CETO 2 pin connectors
are delicate. A few no-operation problems were traced to broken wires
inside the connector-wiring sleeve. In fact, unless you are very
careful, sliding the connector plastic sleeve back to inspect the wiring
may in itself cause the wiring to break.
In any case, resoldering should be done only with a low wattage (25 to 40) pencil type iron, being very careful to not linger too long on the connection as the hard plastic holder in which the pins are molded may melt.
As a result of this problem, I have been experimenting with homemade connectors that are less delicate. If I'm satisfied with the results I'll describe how to make new connectors in the next newsletter.
5. The CETO Actuator. Most people are initially disappointed with the low power of the actuator, which requires very careful linkage arrangements for rudder movement with minimum friction. The basic problem is that we have become spoiled with the power available from modern RC servos.
But after numerous attempts to make a better actuator, I have come to appreciate the CETO. For the amount of current drain (only about 40 milliamps) the CETO actually has remarkable power. All the attempts I've made so far have resulted in double or triple the current drain, which in turn would require larger and heavier batteries.
So I've gone back to the CETO and concentrated on making lightweight and very low friction linkage and rudder pivots. The result has been very good, especially noticeable in very snappy action when using a pulsing transmitter. The other thing I have learned is that with a very low friction system, a much larger rudder can be used: two or three times that recommended.
6. The TWIN TURBO. You have probably seen the ads: a complete RC system for only $12.95, plus $4.95 for shipping and handling. It's for real-- a two channel 27 mHz system, with a neat little two-stick transmitter and a Twin Turbo Fan/receiver. The latter weighs only two ounces, including two independent little DC motors. Those little motors alone are fine items.
Each control stick controls one channel which controls one motor. With the sticks in neutral, the motors don't run. Push one stick forward and its motor runs forward. Pull that stick back and that motor runs backward. Same for the other stick. Thus you can run both motors forward or backward simultaneously, or each motor separately. Or, you can run one motor forward and one motor backward, simultaneously.
This is the mode of control used to fly RC helium balloons indoors. In fact, the Twin Turbo manufacturer sells a 4-1/2 ft Blimp kit and a 38 inch diameter Saucer balloon kit, which are perfect for flying the Twin Turbo system indoors. You can find out more by calling the SG Corp. Number: 1-800-431-9002.
Here again we have a single frequency 27 mHz transmitter and a broad band receiver. The range is not great, but good enough for indoor flying. Now the challenge is to fly a model plane with this system. One of our subscribers, Clyde Geist, has done just that, in spectacular fashion.
Clyde has flown a nine hundred (!) square inch
4.1 ounce indoor model for several minutes, using the Twin Turbo motors
to provide directional control for the model which uses another, larger
electric motor for forward thrust. He says that the details will
be in a magazine in a few months (probably Model Airplane News).
The next interesting development will be to see if someone can use the Twin Turbo system for both thrust and directional control. This works fine for the balloons. I think it can be done with a 3 to 4 ounce model with about 150 to 200 square inches of wing area.
Meanwhile a quick way to have some fun with the Twin Turbo is to scotch tape the receiver/motor/battery unit to a 1/2" slab of styrofoam sheet about six inches square-- simply float it in the bathtub or swimming pool and turn it on!
7. C02 Power. I now have about 40 flights on my little two ounce 23" wingspan (1/2 size) version of my 1951 RC model. It's rugged and has absorbed a lot of punishment flying outdoors. I'd like to fly it indoors but it is quite fast, which means it either needs a pretty big flying site or needs to be lighter so it can fly slower (with reduced power).
The Brown A23 C02 motor is marginal outdoors (almost dead calm) and the C02 doesn't put out all it needs on 90 plus temperature days. Indoors and particularly at temperatures of 70 or so, it would do much better. Frankly I'm surprised it flew at all in the heat. What helped was to keep the big C02 bottle, which I use for charging the little airborne tank, in a foam cooler with ice. Chilling the big bottle keeps the C02 liquid which provides more power and a longer run. A quick charge and immediate launch enabled me to fly when several said it was too hot for C02 flying.
Why bother with C02? Well, it's the lightest power plant system available for flying little RC's (other than rubber power). I also like the flexibility of prop choice that C02 allows--the higher torque permits large props to be used, at reduced RPM, for longer flights. The A23 motor system weighs only a half ounce, the CETO radio is a half ounce, 56 the model can be fairly easily be built to weigh an ounce, or even a half ounce.
The other neat thing about C02 is the almost instant re-fly capability-- a one second recharge and, pff it goes again!
8. Electric Power. The key to many rapid reflights with electric is to use Sanyo cells. 50 mah Sanyos in place of the CETO supplied Varta 30 mah cells can be charged much more rapidly than is safe for the Vartas. For example, using four size D Alkaline cells in series to charge three 50 mah Sanyos can be done in one minute.
The weight of the three Sanyo cells is only about 3 grams (about 1/9 of an oz.) more than the Varta combination and by soldering them together no battery box is needed. Regardless of all that, the only point of this is to indicate that Sanyo NiCads accept a much higher charge rate than Vartas. On the other hand, if the Varta cells are charged normally overnight they are good for about an hour's operation and with also charging them from the transmitter in between flights there should be enough power for a busy day's flying.
The major advantage of using the Sanyos is simply
that they can be rapidly recharged if run down; more important if the batteries
are being used to power the model's prop than the very low drain CETO receiver
8. CETO Prices. They jump up and down depending on the source and the dollar exchange rate against that of Czech currency. I have sold the complete RC set for both $135 and $145, postpaid. Currently I can do it for $135 and I hope to be able to hold that price for awhile. But it depends upon what I have to pay for any individual shipment. I don't expect the price to go below $135, but it could easily go to $150 or more. I'll go out on a limb and hold the price at $135 through August '95. After that we'll see. Meanwhile there's nothing on the market comparable to the CETO. More next time.
Phone or Fax: 703 273 0607
CETO CLUB NEWSLETTER NO. 5 10-95
1. Error in last issue. The wiring diagram for the CETO transmitter Pulser showed a wrong connection. (corrected in the new image) RC pioneer Fran McElwee (New Jersey) spotted the mistake. Thanks, Fran.
Note: Fran has been flying tiny RC models for years, still using the original radio equipment and typically powered by Cox .010 engines.
2. A better battery for CETO's. The CETO Receiver/Actuator battery pack uses three 30 mah NiCad Varta cells. The pack works well except for one problem--it is delicate in regard to recharging (the normal charge rate is only 2 to 3 milliamps!). Thus, while, the battery pack is good for about an hour's operation (after an overnight charge) it apparently is not suitable for fast charging.
Sanyo cells, however, take fast charges very well. 50 mah Sanyo cells, for example, can be charged in from 1 to 5 minutes at a charge rate of from one amp to half an amp. At those rates you can tell when the Sanyo pack is charged by simply feeling it as the charge progresses-- when the pack gets noticeably warm (preferably not hot) it's fully charged.
At Cloud 9 RC we have obtained a supply of replacement battery packs for the CETO set. They consist of three Sanyo 50-mah cells wired in series, with a CETO compatible socket and a tiny on-off switch in the battery cable. The switch is actually smaller than the CETO slide switch! The battery pack assembly is only a few grams heavier than the CETO pack assembly, but it provides almost twice the capacity (50 mah vs. 30 mah). The cost is better, too-- only $4, postpaid.
3. CETO Plugs and Sockets. We have found it necessary to resolder connections several times-- the CETO wiring is fragile where it joins the plugs and sockets. In resoldering the wires it is easy to melt the plugs and sockets-- anything more than a quick dab with a small soldering iron tip quickly destroys the connector.
Cloud 9 has replacement connector sets. The cost is $5 (post-paid) for four connector sets (4 male and 4 female connectors).
4. Small wheels. Little models typically need little wheels, often 1" diameter or less. A good source for these are the wooden clothes buttons sold by many art and craft shops. Drill an axle hole in the center and fill up the thread Holes with balsa dust and glue (or leave them unfilled). The plastic caps from 35-mm film containers are also suitable, but these require attachment of a small tubing axle holder, which can be secured with a dab from a hot glue gun.
5. Larger Rudder; Linkages. CETO instructions
recommend a very small rudder, because of the relatively low power of the
actuator to move the rudder. But we have found that, with rudder
hinging that is essentially friction-free (such as by attachment of the
rudder to the vertical fin by a few figure-eights of very light sewing
thread) and by a very light pull-push link between the rudder and the actuator
(such as a hard balsa 1/16" square stick lightly coated with Cyano cement)
a rudder of up to 2 square inches is feasible.
Page 2 10-95
Attachment from the balsa stick to the rudder and actuator should be with very light music wire (.024-.028" dia.), with "Z" bends on the ends. Important: don't get any glue on the thread in between the rudder and the fin-- with the pull-push rod disconnected the rudder should flop back and forth freely when the tail is waved to and fro.
Even with a comparatively fast model, a larger rudder can be okay-- higher speed may blow the rudder back so that full throw isn't possible as it is when ground testing, but at higher speed less rudder throw is needed, to avoid over-control.
The critical thing after achieving a minimum friction rudder hinge is sufficient rudder movement and this requires careful setup of the linkage. If the rudder simply moves the same number of degrees as the actuator arm, only about 15 degrees of rudder movement each side of neutral is provided. It's better if you can get 20 to 30 degrees each side of neutral. To get that requires rudder pivot geometry about half that provided by the actuator. This means that the attachment for the pull-push rod should not be more than 1/8" out from the rudder pivot center; hard to do but achievable.
A much simpler way of getting a more effective rudder, however, is to simply mount the actuator in the tail of the model, with the actuator pivot lined up with the rudder hinge line. The easiest way to do that is to simply glue the rudder right on top of the actuator arm! For example, make a rudder about 3/4" wide and glue it so that the actuator pivot is back of the rudder leading edge-- this provides a little bit of rudder balancing so that the rudder is actually more effective.
With a rudder about 2" high an upper pivot should be provided. A very light pivot can be made from .025 music wire glued in the top of the rudder and supported by a 1/64" plywood or plastic arm glued to the fin. With this setup, no thread or other kind of hinging is needed. Note: the very light weight of the actuator means very little nose weight is required for balance on most models. We've done several models with this arrangement and like it better than the pull-push linkages.
6. Micro Models in Delaware. At the Vintage R/C Society's 6th Annual Reunion over the Labor Day weekend: there were seven very small (24" span or less) RC models, five of them controlled by CETO radios. They were powered by Gas, Electric, and C02. Four were reduced size versions of Hal deBolt's Live Wire design from the fifties. Note: Full size (24" span) plans of the half size Live Wire Trainer plans are available for $2, from VR/CS, 4326 Andes Dr, Fairfax, VA, 22030.
7. Henry Pasquet of Ellisinore, Mo. Henry has probably done more flying, outdoors, than anyone else in the USA. He has an assortment of models, all C02 powered, which he flies a lot.
Several are balsa stick and tissue free flight
type scale models which are commonly flown with rubber power. One,
however, looks like a conventional type competition type free flight, normally
flown with gas or electric power, with the wing mounted on a sheet balsa
pylon. This is the Czech made AIKA design, available in Kit, Semi-ARF
and ARF versions. As sold, it is intended for C02 power, but would
work equally well-though a little heavier-- with electric power.
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The AIKA is a spectacular flying outdoor model, with sheet balsa fuselage, with a built up wing of about 27" wingspan. It weighs, without power and radio, only about 2 1/2 ounces. The AIKA is designed for and comes ready for immediate CETO radio installation. In fact, the ARF (Almost Ready to Fly) version can be ready for flight within an hour or less, assuming the C02 motor and CETO radio are ready to install. I have seen a video tape of Henry flying flight after flight of his assortment of models, in the middle of a field full of cows!
8. West Coast Source of CETO, AIKA, C02, and other items. Hobby Club, 23141 Arroyo Vista, Suite 210; R.S.Margarita, CA is the U. S. importer of CETO and other Czech made items such as model kits suitable for the CETO radio. Cloud 9 RC, on the East Coast, is a Hobby Club dealer offering many of the CETO and related products.
9. Indoor vs Outdoor. These are two different animals. While it is possible to have an outdoor model which can be flown Indoors, the Indoor site would usually have to be very large; as big as a football field, like the field house at Johnson City, Tenn. The basic problem is airspeed. Except for almost absolutely dead calm air conditions, an outdoor model typically needs to fly at 5 mph or above, in order not to be blown away.
Indoors, a model flying that fast is difficult to control in a manner to avoid crashing into walls or other indoor obstacles. It also means that such crashes typically result in extensive damage to the model. A lighter and slower model flown indoors does much better. Heavy is not as bad as fast. In other words, a 4-ounce model flown indoors at one or two mph (a slow walk) does okay-- but this usually means that the model must be very large. A smaller model, at 2 ounces or less is okay indoors, but this usually means the model is very fragile. A 2-ounce model, such as my 51/5O (1951 RC design/5O percent size) is rugged enough for outdoor flying but is too fast for safe flying indoors.
Most CETO radio flying is apparently being done outdoors. What would help for indoor flying is some form of altitude limit, as can be provided with motor shutoff, or speed control, which the CETO doesn't have. That's easier done with electric than with C02. Again, a large (high ceiling) site is okay for rudder-only flying, but there aren't many of those sites around. So we are still at that state of affairs where some ingenuity is needed to bring RC indoors at commonly available sites. An indoor basketball court is available in most neighborhoods. So this is still a primary goal, in order for indoor RC to become more common, to be able to fly close to home.
We can do indoor RC with helium blimps, with the Twin Turbo equipment currently advertised in most model magazines. That is a very practical activity, since the Twin Turbo system provides altitude control via controllable electric motors. But the big challenge is to fly model airplanes indoors with RC.
That can be done with the Twin Turbo system, with a relatively large and very light airplane. One possibility currently being explored is the use of a Rogallo wing design, which provides lots of wing area at low weight. It also has high drag, which might not be bad as this assures that the model will fly slowly.
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Lots of food for thought in all this. We'd like to hear from others with any ideas on the general subject-- we can use this newsletter to explore the possibilities and report results.
10. Larger, Slow Turning Props. In general (not so in the case of small ducted fans as used in the Twin Turbo RC system), it seems best to use large slow-turning props for slow moving model aircraft, such as those usually flown indoors. With C02 this comes naturally-- C02 pressure provides a lot of torque which can turn big props easily while at the same time conserving energy for longer duration.
For electric motors, gear reduction drives are the means to drive large props slowly. Ratios of at least 3:1, but preferably up to even 10:1 can be used. The result again is more torque, plus lower battery drain for longer runs.
Slow flying models also help provide slower climbs,
a desirable factor for indoor flying. In fact the right combination
can limit altitude to only 10 or 20 feet, so that no motor speed control
or cutoff is needed. More food for thought.
NOTE: ADDRESSES AND/OR PRICES ARE NOT CURRENT
CLOUD NINE RC
4326 ANDES DRIVE
FAIRFAX, VA 22030
CETO CLUB NEWSLETTER NO.6 12/95
Christmas and other activities this month delayed this newsletter several weeks-- sorry about that-- but life is more normal now, so here is more little plane stuff:
1. CETO Battery Packs. In the previous issue we told you about Cloud 9 RC's 3.6 volt 50 mah Sanyo NiCad battery packs, with two-inch wire leads and a CETO compatible socket; with a tiny on-off switch. The price on these is $4 postpaid, with the switch, or $3 postpaid without the switch.
The Sanyo pack is 7/16" dia. x 1 7/8" long, and weighs 12 grams. Total CETO airborne weight with the Cloud 9 battery pack is 18 grams vs. 14 with the original CETO battery box, batteries, and switch; only 4 grams more (.14 oz.)
The neat thing about the Sanyo pack, besides its greater capacity (50 mah vs. 30 for the original CETO batteries) is its fast charge capability-- only one to two minutes vs. ten hours or overnight! Charging the Sanyo pack is simple; using four C or D size NiCads or Alkalines in series, connected directly to the Sanyo pack (plus to plus, minus to minus). Leave connected for only a minute or two, until the Sanyo pack feels warm. No meter or measuring involved. With each Sanyo pack we provide a CETO compatible plug for connecting the charge pack to the Sanyo pack.
Note: the Sanyo pack is especially good for various control systems some CETO club members are playing with, where higher current drain is involved. Example: using a tiny motor from a small conventional RC servo to move the rudder. An arm about half an inch long is fastened to the motor shaft and it is restricted to about 60 degrees of rotation by a couple of mechanical stops. A very light spring holds the motor shaft arm full over against one stop when there is no power to the motor. Then, with power on, the motor arm snaps over to the other stop.
Lots of power (compared to the CETO actuator) is provided by the motor, though at higher drain. This motor/actuator works best with a pulse control system as the oscillation of the motor reduces the average current drain, especially if the pulser is adjusted to not quite stay full over in the signal-on position.
2. CETO Batteries. For those who need or prefer the minimum weight 30 mah Varta Cells, these are available from Cloud 9 RC for $ 2.95 per cell, or a set of 3 for $ 8.00, postpaid. CETO battery boxes, with CETO switch and wiring, are $ 8.00, postpaid.
3. Tiny Motors. Kenway Micro Flight of New
Jersey sells a super-small motor, called the KR2, which is only about 5/16"
diameter x 5/8" long. See their ad elsewhere in this newsletter about
the KR2 and other neat little plane items.
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4. Alternative Transmitters/Control Systems. One of our newsletter subscribers, Denis J. Van Orman Sr., 308 Mosser St., Altoona, PA 16602, advises that he has an Ace rudder-only 27 mHz pulse system with a Baby Twin Adams actuator for sale, in excellent condition, for $90. He also has a 27 mHz Mattel system for $ 70. Contact him direct for either system. Denis says his CETO system works well with both transmitters. Likewise my CETO system works well with an old single channel 27 mHz Testers proportional pulse transmitter.
5. Little Servos. There are several to consider. Cannon has one to go with their little RC system. Hi-Tech RCD also has one, their HS8O SubMicro. These servos are like the conventional, ones we're used to in bigger models, but they are much smaller and lighter, with gears for good power. They require conventional receivers, like the 2 channel subminiature "Shredder" from Hi-Tech RCD, which is relatively low cost, crystal-controlled, and available on the various 27 mHz frequencies.
6. CETO Plug/Socket Repairs. Handling the wiring between the battery pack, receiver, and actuator, especially the plug which regularly has to be connected and disconnected for charging, needs to be done carefully-- the solder joint between the wire and the plug or socket is fragile and can be a source of intermittent connection underneath the insulating sleeve.
Resoldering a connection can improve the situation. I find it better to discard the dual wire sleeve and substitute individual wire sleeves, as is typical with conventional plugs and sockets. See the drawing in this newsletter to see how a better connection can be made.
The basic point is to strip enough insulation off the wires to permit the point of a small soldering or on to transmit heat from the wire to the socket. This avoids touching the plastic connector body, which melts easily if touched directly by the iron. Tin the wire ends before contacting the socket. Then insert the tinned end into the socket and touch only the point of the iron, with a drop of solder on it, to the wire-the melted solder will then wick into the socket hole. Remove the iron as soon as the wicking occurs. Then slide the pre-positioned individual wire sleeve to cover the exposed wire.
Hint: it usually helps to have the socket positioned vertically, such as in a small vise, so that the wire points down into the socket when soldering. Gravity will thus help the wicking action.
7. CETO Receiver Switch Problem. The little slide switch has a relatively long stem sticking up, which may snap off when operating the switch, unless care is used to push the stem only at the bottom. Though not impossible, it is difficult to repair the switch if the stem snaps off. If the switch can't be repaired, an alternative is to get the pull-push switch sold by Cloud 9 RC.
Actually smaller and lighter than the CETO switch
(only about 1/4" square and about 3/32" thick), the alternative switch
is available for 75c each or three for $2, postpaid. The switch is simply
glued carefully) to the model structure. Or, to make the switch removable,
a small (#2) flat-head machine screw can be glued (by the flat head) to
the side of the switch. Screw length can be from 1/4"to 1/2", depending
upon how thick the structure it is to be fastened to. Use a nut to
secure the screw/switch assembly.
Page 3 12/95
But, to avoid the problem in the first place, you might cut down the length of the CETO slide switch stem to only about 1/8". It will than take more pressure of operation with less chance of breaking off.
8. Twin-Turbo. The receiver/prop drive works best with more than 3 volts. Three NiCads for 3.6 volts is good. 3 alkalines for 4.5 volts is better, 4 NiCads at 4.8 volts is better yet. Even five NiCads for 6 volts can be used. The Twin Turbo producer (S.G. Corp.) sells ready to use NiCad packs of 3, 4, or 5 cells. You can call them toll-free at 1-800-431-9002 to get prices and/or order. They also have a neat little charger for these packs that works off 110 volts AC.
For those who like the convenience and simplicity of using 3-volt Lithium batteries to operate the Twin-Turbo, Cloud 9 RC has a bargain offer. Radio Shack sells a 6-volt Lithium battery pack for $12.99. It consists of two 3-volt 1300 mah cells encased in a plastic shell. By stripping off the plastic (but carefully so as not to short-circuit the cells) the two 3 volt cells can be separated and used individually.
In this manner you get two cells for $6.50 each, instead of their $7.99 single cell price. But Cloud 9 RC has a better way to go. It sells the single cells (by Maxell) for only $5 postpaid. Or, get their plastic encased 6-volt battery for only $8, postpaid, and the net cost per cell is only $4!
9. Simple Max-Throw Rudder Hookup. In the previous newsletter we showed the linkage geometry required to get maximum rudder movement from the CETO actuator, using a more or less conventional pull-push linkage. A simpler and less critical hookup can be used instead, using common sewing thread going from one actuator arm to the rudder post (leading edge of the rudder), wrapping around the post 1 1/2 turns, then back to the other actuator arm.
If the rudder post is a common round toothpick glued to the front of the rudder1 it will have a diameter of about 3/32". This small diameter for the threads to rotate (instead of the typical bellcrank type arm sticking out the side of the rudder) will easily provide 60 degrees or more throw. The rudder post acts like a pulley and due to the small diameter gets a lot of rotary motion from the small actuator movement.
It's important to secure the thread to the post
to avoid slippage. This can be done by a tiny drop of glue on the thread
where it contacts the front of the rudder post. But better yet I drill
a small diameter hole from one side to the other of the rudder post, wrap
the thread from the actuator arm halfway around the post then thru the
hole, continuing around the post and back to the other actuator arm, as
per the drawing page in this newsletter. This through-the-hole arrangement
allows the rudder position to be adjusted, by loosening the thread to allow
it to slip through the post, then tightening the thread again to avoid
slippage-- but not too much tightness; just get rid of any slop in the
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10. CETO Actuator Power. George Pearce (Chesapeake, VA) and I have done some tests. They show that the CETO actuator will lift (pull) about two grams at normal voltage (3 or more). It is not much to work with, but it is enough if care is used to minimize friction in the control system.
Next step will be to try more voltage: four little NiCad cells instead of three. If it isn't too much for the receiver, this should help provide more actuator power. It definitely does when higher voltage is provided directly to the actuator alone. More on this in the next issue.
I also have a promising alternative to the CETO actuator that may provide more power without much increase in current drain. Weight may also compare favorably with the CETO. Meanwhile, the CETO still is an amazing little actuator, to provide a workable amount of power in such a small and light package and with so little current drain.
To beat it performance-wise is a real challenge. It has been done in some home-made actuators, but the basic problem to date is that it requires winding many turns of extremely small diameter copper wire (#40) to produce a good coil. Most people don't want to bother-- it's kind of like making microfilm indoor models: extremely fine work is required to avoid breaking the wire. But we're working on the problem, to find a reasonably priced source of ready-made and suitable coils.
11. The Future. As we go into 1996, there is much on the horizon to indicate a healthy growth of subminiature R/C model activity. We'll see more and better products and progress. In the meantime, it's great fun using what we've got as we look forward to the improvements to come. Happy New Year to all!
(PRICES AND ADDRESSES ARE NOT UP TO DATE -ed.)
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