Help Selecting Props...

Rather than re-post a bunch of stuff here, I've uploaded a prop selection guide on my website at http://www.RCDave.net . You can also link directly to it on my server at:

http://www.scootworks.com/rdrcdave/props.html

I hope it helps some of you!
Dave AMA119484
http://www.RCDave.net

How to select the correct glow plug...

There's loads of info on this topic, and I've consolidated what I thought were the best pieces from James McCarty, Brian Cooper, and Brian Gardner . Rather than repost a pile of stuff I have on my website, I'll point you to it. You can see it on my website at http://www.RCDave.net or you can link directly to the info on one of my servers at http://www.scootworks.com/rdrcdave/gloplugs.html . I hope this helps some of you as much as it has helped me!

Dave AMA119484
http://www.RCDave.net

  

Checking out the electronics on my Spoiler...

After patching a bit of covering, cycling the batteries, lubricating the engine, and a general good check over... here's running the servos a bit. Looks like she's ready to take to the sky again!

Dave AMA119484
http://www.RCDave.net

Repairing "China Film" with Clear Monokote

I've used clear Monokote for years in a variety of repairs. With so many ARFs now being covered in low temp "China Film", despite the mfg's claiming it to be a name brand covering, many pilots find the covering coming loose on glow fuel powered aircraft. The fuel residue from glow fuel will find it's way under the edge of the covering, soften the adhesive, and resealing with a covering iron is only a temporary fix. I've had this happen a number of times and have found a permanent fix for the problem... Clear Monokote covering!

I recently pulled my old ERC Spoiler down from my storage racks and discovered the clear outer layer of covering had let go, leaving only the white pasty color layer behind. The clear outer layer was peeling off, and could not be reattached over the color. I pulled the clear layer back in place and tacked it down to the wing with the sealing iron on low temp (abt 250 deg), cut a thin strip of clear Monokote, and applied is across the edge of the failing China-film joint. I sealed the Monokote at 300 degrees, and the repair is complete and permanent. You have to be careful where your iron touches the China-film, some of that stuff melts very easily and at a very low temp, but overall I've found this to be my best way to repair China-film, short of recovering the aircraft.

Here I've cut a strip of clear Monokote and have peeled the backing away, in preparation for sealing to to the repair area on my wing.

There's nothing special about the clear Monokote,  you could use any color of iron on covering, but the clear doesn't smear color onto the original covering, and the original covering can be seen through it... it's almost invisible.

Here, the clear strip has been ironed into place over the failing China-film joint, and is only seen when looking up close.

My spoiler, ready to go, with no visible covering repairs from the china-film problem. I've had the airplane several years, so there are several small repairs with clear Monokote on it!

Dave AMA119484
http://www.RCDave.net

Everything You Ever Wanted to Know About Glow Fuel, and more...

Without reposting a ton of stuff, check this out on my web server at:

http://www.scootworks.com/rdrcdave/fuel.html

I linked to it directly from my website at http://www.RCDave.net . It's well worth the read!

Dave AMA119484
http://www.RCDave.net

My old DaveCharger still works...

This is an old field charger I designed and built back around 1985. It's a constant current charger design that is essentially two chargers in one enclosure...one for RX and one for TX. The input voltage needs to be a couple of volts ahead of the battery being charged, so I would often run mine on 24 volts at the field to quick charge my transmitters. My later pulse charger design could charge a 9.6vdc TX battery from a 12 vdc field box battery, but since I usually kept a spare field box battery and some clip leads with me, it was no issue to operate on 24 v if needed.

It uses a pair of LM317's wired in a current regulator configuration, with values calculated for about 600mah output. The output LEDs have a parallel resistance to allow full illumination at 600mah output. Once a NiCd or NiMH battery begins to approach saturation, the charge current deteriorates and the LED will fade and turn off around 250mah, indicating nearly full charge and ready for use.  The photos below show a few pics and an old "toilet paper" drawing of the circuit. While not nearly as "whiz-bang" as all of the digital chargers of late, it's easily built with a few pieces from Radio Shack and some junk box parts. and will provide years of service.

Here you can see one of the two LM317's . They are installed to the heat sink with insulators and thermal heat sink compound. They can not be electrically connected to the heat sink. 

My crude schematic. The 2 ohm 10 watt resistor for each charger circuit is a pair of 1 ohm 10 watt resistors in series. The 5 ohm 4 watt resistor in parallel with each LED is a pair of 10 ohm 2 watt resistors in parallel and  attached to the front panel with silicone adhesive. These can be seen in the last photo. There is no difference in the circuitry for the RX or TX charger ports, since it's current regulated.

Dave AMA119484
http://www.RCDave.net

Engine Break-In Tips

A good guide Breaking in your R/C Engine...

---

This is a great guide for the correct break-in basics of R/C engines. Follow these guidelines to hopefully have a long and healthy R/C Engine Life!

Breaking in your Engine Original publication by Norman Osborne Adapted to current views by Pé Reivers Standard fuel blends are: Glow fuel: 72% methanol 10% nitro 18% oil (castor or synthetic) Glow fuel for break-in: 80% methanol 20% oil (castor or synthetic) The object of running in an engine, is to get the engine to the point where all the rubbing surfaces are perfectly mated to each other at all temperatures likely to be attained, while causing as little wear to the engine as possible in the process. The benefits of doing this properly are twofold; the engine would be a 'better' engine throughout it's life, and that life would also be extended. A good tip is to use an old glowplug when first running in an engine, as often minute pieces of metal from the running in process or swarf left from manufacturing can destroy a glowplug in seconds. The method used to achieve this is simple. Run the engine very rich and lightly loaded at first and gradually increase the amount of work the engine is allowed to do, at the same time gradually increasing the temperature that the engine is allowed to attain, by judicious use of the main needle valve. This gradual process is spread over approximately the first half hour of the engine's life when it should be ready for its first full speed run. During all running of new engines, the setting should be on the rich side of peak power. All running-in during the first tankfuls is done with the throttle fully open. Ringed Engines Start by using one of the smaller propellers recommended by the manufacturer and a minimum of 20% of oil in the straight or low nitro fuel. When using synthetic oil, addition of castor for the first run(s) is recommended by most manufacturers and engine authorities. Run the first tankful absolutely soggy-rich, keeping the glow-plug lead attached if necessary to keep the engine running. Keep all runs of short duration of one-half to one minute, with a few minutes cooling down time between each. The number of heat cycles makes the metal "set" and speeds up the final fit of the components. The rich mixture and the short runs prevent the temperature from rising too much. Debris that forms will be washed away by the excess fuel and oil. For the next few runs set the main fuel needle to give a very fast four-stroke with just the occasional hint of two-stroking. Allow engine to run for 30 seconds and then stop for a two minute cooling period, Start again for 30 seconds then allow to cool again. Gradually increase the length of the full throttle runs, unless the engine shows a tendency to bind, which can be heard by the labouring sound and unwillingness to maintain a steady rpm. At the end of two tankfuls lean the engine out to the point where the engine is on the verge of two-stroking and four-stroking and go fly, reducing throttle from time to time to allow the engine to cool a bit. Keep this up for about four litres of fuel. By now the engine should be steady running, without any tendency to sag, and can be leaned further to the point, that max. power is achieved. Always back off the needle a bit until a clear drop in rev's can be noticed. That is the standard flight setting for longevity and strong running in the air. During flight, the engine will lean out a bit, so you will be on the safe side of disaster with this setting. If the engine is to be used under more harsh conditions (e.g. with a tuned pipe or high nitro fuel), then it will need some extra running-in under the short-run procedure, using the same fuel as for it's intended use, but with extra oil added. 25% oil is not too much for the first runs of a racing engine and will do it a lot of good. All this might seem a long-winded process but it is necessary to get the best surface finish with the least wear inside your precious engine. The reason for everything being done in small and gradual steps is that the rubbing surfaces have to be mated at gradually increasing pressures and to further complicate this the shape of the parts change as temperatures are increased. As an illustration, the cylinder and piston are round and parallel sided when made. As the engine warms up the top half of the cylinder gets hotter than the bottom half and so expands unevenly, worse than this the exhaust side of the liner runs hotter than the transfer side, then to add to the problem the front of the engine (in the airstream) runs cooler than the rear of the engine, so you can see the liner would be anything but perfectly round and parallel when thoroughly hot. That is the reason, that a well run-in engine has a bit less compression during starting than a new engine. The piston and ring are subject to similar stresses. The ring alters its length depending on temperature and is also going up and down a bore which is no longer round or parallel sided and is guided through this operation by a piston which gets hotter at its head where it is in contact with the burning fuel mixture and therefore the diameter of the head is bigger than the walls. The exhaust side of the piston is hotter than the transfer side so the piston is no longer round or, as mentioned earlier, parallel sided either. All these distortions are larger or smaller depending on the temperature of the engine, so the running-in process has to allow the engine to make the mating working surfaces suitable for all these varying conditions. During the run-in check all screws and bolts for security and if you have to tighten any cylinder head bolts, remember to tighten a little at a time and in diagonal rotation. You might also find the glow-plug has been affected by small metal particles fired at it during running-in. If you have any doubts change it and keep the old one only for running-in only, or throw it away. It did serve it's duty. Running in ABC engines An 'ABC' engine is one with special liner and piston metallurgy, e.g., the piston is aluminium (A), the liner is brass (B), and the brass is chrome plated (C). Generally these are performance orientated engines. When an ABC engine is warmed up, the top of the liner, which made of brass, will expand more than the piston which is made of aluminium. Consequently, as the engine reaches working temperature the piston seal would not be very satisfactory. The manufacturers have taken steps to counteract this undesirable state of affairs by making the liner and piston the correct sizes for when the engine is hot. This means that when cold the piston is a very tight fit at the top of the liner, to the point where some make a light groaning noise when forced over Top Dead Centre (when the piston is at the very top of its travel, or TDC for short). Warning: a new ABC engine should never be turned over slowly, especially when still lubricated by the original preserving oil that the engine is shipped with. That will cause slight, but immediate damage to the top part of the piston fit, because the surfaces are still rough. Little running-in is required with these engines, as the cylinder temperature must be raised to full working temperature as quickly as possible to avoid excessive piston wear due to the very tight fit at lower temperatures. As a matter of fact, it is best to fly these engines out of the box, using a rich setting with occasional four stroking. It is important to use an extra 5% of oil on top of the normal mixture. When bench running, my usual method is to use about 5% extra castor oil in the fuel and set the engine for just below full speed running (throttle fully open, main needle just a little bit rich), and run the engine in short cycles of approximately 30 sec's. full speed and 5 sec's. at 1/3 speed, for the first 15 minutes. This keeps the cylinder temperature up and the slow running should give time for any hot spots to cool down somewhat. For the next 45 minutes use the engine normally but keep it just a touch rich (just 2 or 3 clicks). After that, normal fuel can be used as per manufacturers recommendations. Setting the main needle This is a most important setting as not only does it set maximum power but it also controls the running temperature of the engine and from there the length of the engine's life, the life of the glow-plug and the overall reliability of the engine's running in flight or elsewhere. Engines don't very often cut out in flight because they are set slightly too rich, but they most certainly do when set too lean. It takes about five minutes to learn the drill for correct needle valve setting so it's worth taking the trouble for the long term benefits gained. The drill is to start the engine on low throttle, for safety and usually easier starting due to higher gas speeds through the venturi and consequent better atomization of the fuel droplets. Once started, open the throttle fully and set engine to just four-stroking rich. Leave the engine to warm through thoroughly at top speed for a few moments, then adjust the needle until the engine is just off four stroking and running smooth. At this point, further leaning of the mixture results in RPM increase. From this established point richen up slowly again until a small but definite drop in RPM is noticed, with the engine still two-stroking. Lift the nose of the model up vertically and if the small loss of RPM is regained then you should have a good flight setting. If the model has a tendency to go rich or go lean in flight then an extra allowance will have to be made for this on the final setting. The aim of this is to give maximum power from the engine when it is needed most, either when the model is climbing or when turning sharply and will also give sweet and cool running during level flight, the best of both worlds. What happens when an engine is set too lean The glow-plug engine keeps running because the heat of compression and the catalytic action of the glowing plug material with the methanol mixture ignite the charge in the cylinder at the correct moment. This catalytic action also keeps the plug lit. Sometimes an engine will start without adding glow to the plug after it has been stopped for several minutes. A little thought will let you see that the whole system is very temperature dependent. No spark to set it off, no injection of fuel to set it off. Just the combination of these two properties. When an engine is set lean i.e., for maximum RPM at the start of a tankful of fuel, anything which slows the passage of the fuel through the needle valve will make the engine run over lean. Some engines will not continue to run in this condition and so cut dead but the majority will continue to run to some degree. As the tankful of fuel gets used the fuel pressure, as seen by the needle valve, gradually reduces and as a result the engine gets a progressively leaner mixture as the flight continues. As the engine started set in a lean condition it must progress into the over lean condition and maybe go so far as to cut out, suffer from overheating and get damaged. When the engine runs flat out, ignition timing and engine temperature should be as the designer intended but as the mixture gets into the over lean area temperatures will start to rise. This is due to lack of extra internal evaporation of excess fuel, and hotter burning of lean mixtures. Over-lean mixtures can change combustion characteristics in a way that imparts more heat to the surrounding engine structure leaving less for useful work. The fit of the moving parts becomes worse, and friction rises. As a result of this the incoming charge is heated a little more than it should be and when compressed is at a higher temperature than it otherwise would be. The secondary effect of the engine structure being at a little higher temperature is that the glow-plug element is also a little hotter, which advances the onset of ignition. As already explained, ignition timing is controlled by the temperature of the compressed fuel/air mixture combined with the temperature of the glow-plug element. The net result of both of these being raised is early ignition in the next cycle.. This early ignition gives just a little more time for even more heat to be transferred to the engine structure before the hot gasses are exhausted from the engine and so jacking up engine temperatures just a little more, resulting in the next cycle jacking up temperatures yet again. This is the slow build situation that causes engine seizure in some cases and in other cases runaway early ignition that makes an engine stop quickly in the air and even throw the prop, as though it has seized, but in fact feels perfectly O.K. and runs O.K. when it has cooled down again. Many of the modern engines do not reach these extremes but keep running at a steadier but much higher temperature than they were ever designed for. These engines run other risks which are much less obvious. One risk common to ail engines which are run at elevated temperatures is that the oil gets very hot, thins out too far and so can no longer lubricate as effectively as it should, resulting in excess wear and shortened engine life. Synthetic oil will evaporate at very high temperatures without leaving a trace of lubrication. The less obvious damage that can occur is not usually laid at the door of a lean fuel setting but I believe much of the time it is a relevant factor. When the engine has overheated and reached the point of too early ignition the burning mixture expands the gasses well before top dead center and so the pressures inside the cylinder are much higher than they should be. These extra high pressures at the wrong time in the combustion stroke try to force the piston down with greater power than the designer intended and therefore overload the wrist pin in the piston and the little end bearing, the con-rod is more highly stressed, the big end bearings and the main bearings on the crankshaft are also subjected to higher loads. In four stroke engines it is not uncommon that the engine will knock and even kick back and throw the prop. Knocking can be heard, and is a typical sound like tin foil being rubbed. These extra stresses may only result in wear being more rapid than necessary but if it is a regular occurrence it can result in very early bearing failure, and if it happens to be the con-rod that gives up first the resultant damage can be very expensive. With all this in mind, when adjusting the main needle of your engine the catch phrase should be 'The future of your engine is in your hands'. Setting the low speed The need for a low speed adjustment on the carburetor is because as the throttle is closed it lets less air through into the engine and to keep the fuel air mixture within combustible limits the fuel flow. has to be altered, it's too fussy to leave to chance. Most manufacturers have opted for a two needle configuration or something which works in a similar manner. To adjust this low speed mixture start the engine, warm it up and make sure the main needle is properly set. Connect the glow-plug lead to energize the plug and slow engine down by gradually closing the throttle until the engine starts to run badly. At this point adjust the slow run needle to give smoothest running characteristics just a little on the rich side of fastest setting. Having made this adjustment slow the engine further until it runs badly again, now adjust slow needle until engine runs smoothly once more and continue this step by step procedure until the desired tickover has been reached, with the throttle barrel barely 1mm open. Now remove the plug lead and repeat the whole process. If the engine cuts dead in the middle of adjustments it's usually because it is too lean. Having reached a slow tick over we have to check if the engine will pick up properly. Open the throttle to full speed with a smooth sweep, without jamming the controls. I know of many people who demand their engine to respond well to slamming the throttle open, but in two-stroke engines, this is asking for trouble and not to be recommended. If the engine picks up but splutters a little whilst doing so, the low speed needle is a little on the rich side. If the engine appears to miss and then picks up suddenly the low speed needle is slightly lean, and if the engine cuts dead when the throttle is opened richen the low speed needle 1/4 turn and try again, adjusting in small increments. If the engine starts to pick up pretty well and then cuts at about 1/3 speed or so, try opening the main needle two or three clicks. On many engines there has to be a compromise or two to get the low speed, midrange, top speed and pickup to a useable whole, and usually the compromise is that somewhere in the range the carburettor has to be set a little richer than would be considered ideal. Rich mixtures are an assurance for longevity and seldom cause the engine to stop, unless extreme. Four-Stroke engines The previous sections are written specifically for two-strokes, but exactly the same principles apply to a four-stroke, just some of the symptoms are slightly different. When running-in from new use a fuel with 20% oil of which at least half is castor oil for the first runs. A four-stroke cannot be made to four-stroke when rich, it's already doing it, but what does happen is the engine misfires in a rather uneven manner, the richer the setting the more pronounced the misfire. The main needle, after running in, is set in exactly the same manner i.e., just on the slightly rich side of maximum RPM., when the engine is thoroughly hot. The use of a rev. meter is invaluable here, because adjustment by ear is more difficult than in two-strokes. If the main needle is set too lean the engine may slow down with the. exhaust exhibiting a more leaden note than usual and may progress to the point where the engine stops with a bang due to 'detonation' and throws the propeller off in flight, or on the ground and perhaps at whoever is standing in the way. 'Detonation' is like early ignition but the difference is that instead of the mixture burning progressively from the glow-plug outwards, the temperature and pressure in the cylinder are such that the whole fuel charge ignites at the same time, before TDC, stops the piston dead, and blows it back the other way. 'Knocking' or 'Pinking' are like a slightly milder form of detonation that happens late enough in the compression stroke for the flywheel effect of the propeller to get the piston over TDC and therefore for the engine to keep running. Always close the throttle and open the main needle a bit more when this happens as it over stresses, and may damage the engine. The main defense against these phenomena is to run the engine a little richer, and mix in some acetone (1% - 3%) in the fuel to stabilize combustion. Adding some 2% of water to the fuel may also suppress Knocking. (in hot, humid weather). This works in two distinct ways, first the richer mixture will keep the engine a little cooler, thus making the conditions for commencement of 'knocking' harder to attain and secondly and very importantly, a rich mixture is much less prone to detonation than a lean mixture. These two effects work together, either for you or against you depending whether you set the main needle rich or lean. Again, the engine's fate is in your hands. The low speed needle is adjusted in the same manner as a two-stroke except generally speaking it needs to be noticeably richer than a two-stroke, to ensure a good pick-up when the throttle is opened and also on some engines to stop 'knocking', and the consequent risk of throwing the propeller, whilst the engine is picking up speed. In general, speed pick-up from idle is far more better in four-strokes than that in two-strokes A Few General Do's and Don'ts Always keep your engine clean. Choose the propeller that allows the engine to run in the RPM range that the designer intended. Always filter your fuel from fuel bottle to tank and from tank to engine, and keep the filters clean. Don't wipe model with cloth that sheds fibers, some will undoubtedly find their way into the needle valve or somewhere just as inconvenient, and upset the mixture setting. Don't use a damaged propeller, It has a tip speed of over half the speed of sound, and to shed a blade can obviously be lethal. Always balance propellers and if possible spinners as there will be less vibration to affect the engine, model and radio. Make sure your glow-plug battery is charged before you go out. At the end of a days running 'dry' the engine out by pulling the fuel line off with engine running. Apply glow, and keep flicking the prop, until no sign of ignition is left. Then put a few drops of oil (not fuel) in the carburetor and ensure it is dispersed throughout the engine. Methanol fuel attracts water and is corrosive to steel, aluminum and copper bearing alloys. It is also possible, to make a mix with your standard mix oil and cleaning naphtha, drop a bit in the engine intake, ad glow and let the engine run on that mix with the fuel line disconnected. Now all traces of methanol, nitromethane and nitric acid will be expelled from the engine. Beware! The Naphtha mix can not be used on engines which have silicone parts inside the crankcase, like some YS four-strokes Never store the model nose down in the corner of your garage, going home in the car, or even while cleaning it at the field, if it is fitted with a tuned pipe or an extra large silencer. The exhaust residue which collects in these is a dirty mix of condensed water, methanol, nitric acid and oil which is highly corrosive and would run straight back into the engine. If the engine is badly 'flooded' i.e., liquid fuel in the crankcase turn the model over in such a manner that the excess fuel in the crankcase runs up the transfer passage, into the cylinder through the transfer port (make sure it's open-piston at the bottom of it's stroke), across the cylinder, out of the exhaust port and out of the silencer.   Good Engine Break-in Procedure Adapted from Ed Moorman Pre-lube the engine with some after run oil. Make sure the oil content in the fuel is 18% or more. 20% is better for break in. Castor oil or a castor oil/synthetic blend offers the most protection as synthetic oil burns off during a too lean run and offers no protection. I won't use a 100% synthetic oil fuel as all engines will always lean out in flight, and I want the added protection of castor oil. Start the engine, let it run rich and at slow speed, not necessarily an idle, until the cylinder fins are warm, then go to full throttle, quickly lean it out to slightly richer than MAX RPM. After 5 seconds, pull the fuel line off or pinch it to kill the engine quickly, so that it doesn't linger at a too lean mixture. Let the engine sit until it is relatively cool to the touch. (The heat/cool cycle) Now, do it again, but let it scream at full throttle for 10 seconds, kill it the same way and let cool. Another heat/cool cycle. Increase the hot run by 5 seconds each run until you have a 30 second hot run. Then do (5) 30 second hot runs. Now it's essentially broken in, so NOW adjust the idle mixture and you're ready to fly. I usually run a tank through at this point at various throttle settings, while I'm adjusting the idle mixture. NEVER go to full throttle after any engine start until the head is warm to the touch. O.S. Engine Break-in Procedure Taken from O.S. .46 FX manual All internal-combustion engines benefit from extra care when they are run for the first few times known as running-in or breaking-in. This allows the working parts to mate together under load at operating temperature. Therefore, it is vitally important to complete the break-in before allowing the engine to run continuously at high speed and before finalizing carburetor adjustments. However, because O.S. engines are produced with the aid of the finest modern precision machinery and from the best and most suitable materials, only a short and simple running-in procedure is called for and can be carried out with the engine installed in the model. The process is as follows. 1. Install the engine with the propeller intended for your model. Open the needle-valve to the advised starting setting and start the engine. If the engine stops when the glow plug battery disconnected, open the needle-valve to the point where the engine does not stop. Run the engine for one minute with the throttle fully open, but with the needle-valve adjusted for rich, slow "four-cycle" operation. 2. Now close the needle-valve until the engine speeds up to "two-cycle" operation and allow it to run for about 10 seconds, then reopen the needle-valve to bring the engine back to "four-cycle" operation and run it for another 10 seconds. Repeat this procedure until the fuel tank is empty. 3. Re-start and adjust the needle-valve so that the engine just breaks into "two-cycle" from "four-cycle" operation, then make three or four flights, avoiding successive "nose-up" flights. 4. During subsequent flights, the needle-valve can be gradually closed to give more power. However, if the engine shows signs of running too lean, the next flight should be set rich. After a total of ten to fifteen flights, the engine should run continuously, on its optimum needle-valve setting, without loss of power as it warms up. 5. After the completion of the running-in adjust the carburetor at optimum setting. Optimum needle setting(1) Slowly advance the throttle to its fully open position, then gradually close the needle-valve until the exhaust note begins to change. (4-cycle to 2-cycle) At this point, disconnect the battery from the glow plug, taking care that the battery leads or glow plug clip do not come into contact with the rotating propeller. If the engine stops when the battery is disconnected, close the needle-valve about 30° and restart. Optimum needle setting(2) As the needle-valve is closed slowly and gradually, the engine rpm will increase and a continuous high pitched exhaust note, only, will be heard. Close the needle-valve 10-15° and wait for the change of rpm After the engine rpm increases turn the needle-valve another 10-15° and wait for the next change of rpm. As the speed of the engine does not instantly change with needle-valve readjustment, small movements, with pauses between, are necessary to arrive at the optimum setting.

Checking throws on my Twist...

I got my old Hangar 9 Twist out of the mothballs and get her repaired. After a few bits, I got a chance to power it up and give a quick checkout. Here's a short video of the servo throws on this bird. You can see more of it in the blog post previous to this one...

Dave AMA119484
http://www.RCDave.net
http://www.RD-RC.net (Archives)
http://www.RD-RC.org (RDRC Primary)
http://www.eastrc.org/rdrc_live/ (RDRC Cams & WX)

My Twist Returns to the Air!

I finally had time to get my old Hangar 9 Twist repaired and ready to go. This time, I had to patch some covering (especially on the wingtips, from dragging them on the runway), replace the throttle servo, replace a defective charge jack on the side of the airplane, and replace the flight battery. I've totally worn the treads off of the tires, and they flop around on the axles like something stupid, but they still roll! Hey, you don't need wheels on an airplane but just a few seconds each flight, right?

This airplane has been thru hell and back over the last 10 years. It has been broken in half twice by donking it into the ground while flying inverted limbo and other fun stuff (once at the 95th flyin), tail totally smashed from going dead stick while trying to hover low (unsuccessfully), canopy smashed from multiple inverted crashes, landing gear blocks ripped out from full throttle touch-n-goes, a zillion holes in covering, cartwheeled (ripping out wing saddle) while flying loowwww circles over the deep grass with Manny, etc... yet she still flys. It is a little heavier from all the repairs, but loads of fun!

It has a little removable hatch for battery & receiver access. Much easier than some of my older airplanes.
 

The old 700mzh 4-cell NiMH pack was only cycling at about 400mah, so it was time to go. The battery wasn't very old, but it sat unused with a partial charge almost 3 years...doing as much harm as daily usage.
 

I replaced it with a 5-cell NiMH 2000mah pack. More voltage and a lot more current. Should make for much longer flight times, and only a little heavier. These systems can handle a 5-cell pack just fine, no regulators needed. The servos are a little faster on a 5 cell, too.

The charge jack had failed, and I made a quick field repair back about 3 years ago. I soldered on a little pigtail connector, and just let it flop around outside of the airplane while in flight. I replaced that with a new charge jack to clean that mess up, too... 

Solid! Plenty of voltage to fly with, now!

These old tires are the originals that came with the kit 10 years ago. The treads are worn off, but they're still fine. These don't have bearings in the center, so the bores are worn pretty badly, as well. Doesn't seem to impact the ability to take off and land, so I'm still rolling with these :-)

Wing back on, checking everything out. Looks like it's good to go!
 

The camera hides a LOT, believe me...in person it doesn't look nearly as well. I thought about recovering it, but then I wouldn't want to bang it around as much... So patched up it stays!

Dave AMA119484

http://www.RCDave.net

http://www.RD-RC.net

http://www.RD-RC.org

RC Electric Motor Info...

I was recently looking over some motors I had to try and determine the proper application, and remembered a chart that one of my sons put together many years ago, when we were selling a lot of motors online. While you might not find the exact motor in the list you are using, you'll find that the numbering system for most motors is fairly universal (motor shell diameter - length / # of turns in the motor winding). The chart shows approximate prop size range recommended as a starting point, and performance when compared to a conventional engine.

For the chart I archived with this data, go to this link: http://www.eastrc.org/electric-motor-ref.htm on my website. I hope this helps some of you!

Dave AMA119484
http://www.RCDave.net

Preflight checkout, Lucky13

I'm wrapping up this cleanup-checkout of my Lucky13 that has been parked about 2-1/2 years. Other than needing a RX battery, the bird seems fine and ready to go. Here's a quick clip of all of the servos in operation. Time to hand it up and move on to the next one. Getting the itch to burn holes in the sky!

Another one pulled from the dust!

Here's another bird that's been unused and hanging in the ceiling for at least 2 years. It's called "Lucky 13" and was sold by East RC for several years (http://www.EastRC.org). It has a 64" wingspan, a flat bottom airfoil, and weighs about 5-1/2 lbs. I set this on up with a Hang-It RC XTRM 3520/06 motor, 12 x 6 e-prop, and fly it on a 4 cell 4000mah LiPO. It flies very scale-like on 4 cells. I've seen others with a similar setup and 5 cells, and it would fly straight up, out of sight.

I put a new 5 cell 3000mah NiMH receiver battery in it before it was stored (it needed the nose weight in my setup, anyway), and now it only cycles at about 1100 mah...so I guess it's time for a new flight battery. Oh well, it's still good for a flight or so, as long as i watch the charge closely. A new flight battery is on the "to get" list for this beast. Here's a few pics...

This is a 800rpm/volt motor, and swings a 12x6 like a .50ish sized glow motor. 

I added some color to the wing to help with visibility, using some scrap monokote I had laying around, and used the iron on about 225 degrees. 

It breaks down for transport pretty easily, and the wing also comes in half from it's internal round aluminum wing tube. 

A pic showing the tip of the wing & airfoil profile. 
 

Time to get back to work...maybe I'll have a day off soon to actually get out and fly this airplane! :-)

Dave AMA119484
http://www.RCDave.net

RC Transmitter Case from the 1980's...

This is a short blog about an early RC Transmitter Case I got from Gator RC back in the mid-1980's. There wasn't much to choose from back then, and many guys were having cloth pouches stitched up with padding to protect their radio transmitters. I bought a hard case from Gator RC and it's still in use today. Much to my surprise, I just discovered they're still in business and even on the web at http://www.gator-rc.com/ . Here's a few pics of my relic with an oldie-but-goldie Futaba 7UAF TX inside...

Dave AMA119484
http://www.RCDave.net

RX & TX Battery Maintenance on the Cheap!

Here's a tip on something I've been doing for 30+ years with great results. Most of us are guilty of charging our airplanes & transmitters for a day of flying, but never making out to the flying site. Our airplanes will sit around a few weeks until one day we have an unscheduled opportunity to go fly, only to find out that our gear isn't ready and waiting...This is especially common on systems where the batteries may be a little older and the batteries don't hold a charge quite like they used to, due to the internal leakage that comes with age of Nicd and NiMH batteries.

There are a number of trickle chargers and such out there to combat this problem, but I found a simple cure that keeps my gear topped off and ready to go very inexpensively. I use the standard chargers that came with my radio systems, in conjunction with a cheapie Christmas tree lighting timer. These timers are often found at Walmart for $3 or so, and can easily handle the very low current requirement of multiple chargers. Connect the chargers to the timer, set the timer to come on for maybe 30 minutes once or twice daily, and forget about it. It's that simple, and I've never had an issue as a result of doing this. Here I have several transmitters and chargers in maintenance mode...

Here's a closer look at the chargers in my workshop, ganged up on a timer. 

 

All of the airplanes in my ceiling mounted aircraft hangars are wired fr maintenance when hanging in storage. Notice the charger in the upper LH edge of this pic...
 

Another timer in the garage feeding some of the aircraft in another ceiling hangar. If I want to put a solid overnight charge on, all I have to do is flip the switch on the timer to the "manual on" mode. 
 

A Hangar 9 Twist and a Spoiler ARF hanging in storage while in maintenance mode. 

Another timer for a different batch of aircraft. It doesn't matter what the time on the timer is set to, nor what time I have it come on for 30 minutes... Very simple!

Dave AMA119484
http://www.RCDave.net

The Butteryfly is back together...

While trying to resurrect my fleet of old birds, I pulled down my old Butterfly. It was an ARF from Green Models, and I've had it about 7 years and have logged a lot of time on it during that time. It flys on a 2 cell 800mah lipo, and will get 30 minute flights on that setup, easily. The motor is a Hobby-Lobby AM400XTm and seems to be a perfect match for it. On days that are extremely calm with some lift, I'll fly it with a 400mah lipo to make it even lighter. With the 800mah pack, it weighs about 15oz.. With a 47" span and 300" of wind area, it's a real floater.

 

About 30 minutes into the flight at sunset last night, the rudder servo failed and it got into a light spin. I killed the power and it floated down and into the tall grass at the flying field with no damage. I replaced the servo when I got back home, and she's ready to go again. You can find these on the Maxford website at http://www.Maxfordusa.com .

Dave
http://www.RCDave.net

The Kadet is all finished!

It only took a few days in my spare time, but it's all finished and ready to fly. I can hardly wait to get this one back in the sky, it's always been a lot of fun and has become my favorite airplane to putz around with. Here's a couple of pics of the completed bird, and you can see some of the work that was done it it in the previous posts...

Dave
http://www.RCDave.net

Setting up mixing on the Kadet...

Folks often discount the Kadet as being a lazy trainer and Sunday flyer... I built this one from 3 wrecks that folks were tossing. It was rebuilt with a solid hardwood spar in a one-piece wing, a Saito 100 for power, converted to a tail dragger, and a much larger tank and battery was used. With it's barn-door ailerons and some mixing, this thing is a blast to fly. I mix flaperons, essentially raising the aileron neutral point as the elevators are pushed down, and visa versa. Huge 3D-style throws with lots of expo keep it a docile flyer with loads of potential as the sticks are tossed around.

This thing will hover with the 100 Saito, will roll into a knife-edge on takeoff and climb out in that attitude, will fly backwards with piles of flap action and low throttle. etc. Over the years of flying this airplane, it has become my favorite airplane to fly.

Here's a short video of the flaperon mixing in action, as well a conventional flap setup I have mixed in...

Finishing the repairs to the Kadet fuselage...

While riding out the remainder of hurricane Matthew, I got some time to tinker on this project a bit more. We were running on a whole house generator (power was out), and it had no problem running the home and my home workshop. Great time to play in the storm!

So, I set about to cover the top of the stab and elevator, and fix a few other items... I trimmed the Monokote a little larger than needed, tacked it in place at 300 degrees F around the root of the stab, pull it out to the edge of the stab and tacked it down there, pulled it around the leading edge and tacked it, then folded the elevator all the way down and tacked it into the hinge line. Once tacked in place, I sealed it all the way around the perimeter, and trimmed the excess away. Using a small T-Pin, I punched a tiny hole in the bottom side of each bay of the stab structure to allow air out... I then set the sealing iron to 350 degress F, and shrank the covering across the entire structure on the top side. I use the heat gun in a circular pattern to get any wrinkles out of the corners, and the iron again to seal the covering to all parts of the structure for strength. You can find the temp chart I put together on my website at http://www.RCDave.net for various covering brands. 

Once the LH side was done, I moved over and covered the RH side of the stab in the same way. 

I cut more material and covered the elevator structure new, using the same methods used for the stab. Once completed, I use the sealing iron and touch the pin holes in the bottom to close those back up.

All finished with the elevator and stab, here's a look from the bottom...

I retained the factory covering on the vertical stab and rudder, but it needed a bit of attention. Sig uses a low temp "china film" of some sort, and it had come loose where the white wraps around the leading edge. I had a bunch of scrap white on the table, so I used little pieces of that to tack to the OEM covering, pull it around the leading edge, and seal it back down. 

The transparent film had come loose where it wrapped around the trailing edge of the rudder. I have clear monokote for this sort of application... I cut a strip, tacked it to the OEM covering, wrapped it around the rear of the rudder, and sealed it down. Good as new! (probably better, hahahaha)

OK, the covering on the fuselage is all repaired, problems in the structure are fixed and reinforced, batteries cycled, fuel lines replaced, prop repaired, and other misc stuff finished. Time to get the wing down and check it over for any needed repairs...

Dave
http://www.RCDave.net