Fly RC

May 11, 2015

Big Electrics need big power… Packs, Chargers, Power Supplies and more

Recently, I’ve been spending more quality time with my electrics… especially my newer/larger electrics like the Carbon Z Cub and the AW Extra 260. Both of these planes are a blast to fly and the AW is, if anything, even better since its conversion to electric. I’ve almost gotten to my goal of only flying either electric power or gas (no glow fuel for me). I recommend the AW Extra for a nice mid-size electric acrobat and the Carbon Z has a wide flight envelope combined with the ability to fly off floats, tow gliders and fly anywhere from wild to mild. Both are great.

The only drawback to this whole scenario is that these bigger electrics need bigger batteries. Bigger batteries need a bigger charger to charge them up and bigger chargers have bigger power needs… In short a whole new series of challenges arise when you get into large electrics. I’m working my way through all of them and have done a bunch of research and some experimentation of my own that I’d like to share.

First, let’s try to put some parameters around the size of the issue… In my case, I started out in what I would call “large” electrics with the Carbon Z Cub. This airplane uses 6S LiPo power with a recommended capacity of 3200mah. Many folks fly larger capacity batteries in the cub to get some longer flight times with sizes up to 5000mah being common. Two other conversions currently underway will use similar size power systems. To charge a single 6S pack at a 1C rate takes a considerable amount of power. For instance a 5000mah 6S pack means charging at 5A and ~25V. Since power (expressed in watts) is equal to current in amps times volts that means about 125 Watts of power are required to charge just one of these batteries at a standard 1C rate which takes about an hour. You can charge slower or faster of course. If you don’t mind a 2 hour charge you only need 62.5 Watts… if you want a 30 minute charge than you need 250 Watts of charging power.

I was hoping to be able to charge 2-4 such batteries at once which means drawing as much as 500 Watts from my charger and power supply system for a 1 hour charge and up to 1000 if you want to get it done in 30 minutes! Keep those numbers in mind.

My mainstay charger to this point was the Hitec X4. This charger has 4 separate channels (independent charging outputs) which can each charge at a 50W rate. For my previous usage where I would sometimes charge as many as 4 of the 3S 2200mah packs, this was not a problem. At around 12V, the 2.2 A charge rate only required ~27 Watts…. No problem. Four batteries charged in an hour with only a little over 100W of input power was easy to take care of. Even pushing all four to double the charge rate (or nearly so) was within reach at the max 200W combined output of this charger. A small 12V supply capable of 20amps or so was more than enough to supply the needed power and the 200W load was easily supported by my existing 900W cheap-o generator. Unfortunately this is clearly inadequate for these 6S packs. At the maximum output of a single channel of the Hitec, the maximum charge rate into the 6S pack is about 2A. A 5000mah pack is going to take 2.5 hours to charge. That’s a long way from the performance I’m looking for. For smaller jobs, the Hitec is still a great charger that I expect to continue to use and highly recommend. If 3 or 4 cell 3000mah or smaller packs is all you need… it is a fine choice. The one I have linked to here is a slightly newer and higher power version of what I have and would work reasonably well for up to 4 cell 5000mah packs or even 6 cell 3000mah packs at 1C charge rates.

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Since I already know I want to run 6S 5000mah (max for now) batteries and I want to charge 2-4 packs in 30 minutes, I can start shopping for a charger, power supply and generator (if needed) and of course a few extra flight packs! I’ll try to do a few posts in the near future outlining the buying decisions I made in each case and how they affected each other. Let the fun begin.

April 29, 2015

Taft Hobby DO-27… First Flight!

If you read the first look post on this plane you will recall that we ran into problems trying to install the first wing set due to (apparently) a misaligned tube in one wing. Once again the folks at Falcon took good care of their customer and shipped out a new wing set and tubes. The new set slid right into place but at this point we noted another issue.

As you can see one of the servo leads in the wing is so short that it is very difficult to plug in at all when you are assembling the aircraft. You don’t have a lot of wire coming out of the wing root either, though it is adequate. The problem is you can’t hold onto this servo lead and apply any pressure to assemble it… Forceps are NOT optional! This is an annoyance, but not a showstopper.

Finally, the last complaint I have about the Taft DO-27 is the hinging of the control surfaces. The folks at Taft obviously know these things are a bit fragile as they include a bag of hinge points to install in case the molded in hinging fails. We added some wound tape in the aileron hinge line on Steve’s plane and we will see how it goes but both the returned wing set and the new set are already showing signs of hinge failure so I think I would consider adding tape to all hinge lines or cutting them loose and installing the hinge pins from day 1 if it were my airplane.

The good news is, once we got the plane assembled and at the field… It looks good and flies really well. The scale details really add to the look and the lights are a nice touch as well. Taxiing on our grass field was easy and with almost no wind and a short takeoff run the DO-27 picked itself up and climbed quickly. Steve shortly had it doing loops, rolls, snaps and more. Power was good and flight times look to be 8-10 minutes of general sport flying… maybe longer with some throttle management.

I’d like to rant about how nice the plane is and in the air it really is. Flying characteristics (based on the two flights so far) seem to be excellent. Plenty of wing, good roll rates, just a generally good flying airplane. Looks too are a plus with nice lights and a distinctive shape and color scheme with a few details thrown in makes for a nice combination. Assuming the wing tube problem is unique, you have to deal with a few issues… First rearrange things to get the tail linkage setup correct. Second, you should probably get some short extensions to permanently attach to the 2 shorter servo wires and make them easier to connect and disconnect. Third, get out your hinge tape or go ahead and install the hinge points day 1. With those 3 things out of the way, the airplane should be a winner. Time will tell for sure.

April 19, 2015

Taft Hobby DO-27… First look

During his recent trip to the Weak Signals show in Toledo, my flying buddy Steve made an “impulse buy” from the good folks at Falcon Hobby Supply and came home with the Taft Hobby DO-27 in Red and White.

The purchase started out with a bit of misstep when the folks working the booth there assured Steve that the plane would accept the 6S LiPos that he had on hand. This is not the case! The DO-27 is setup for 4S use and I very much doubt the speed controller or motor would last long if a 6S was installed! With no 4S batteries in his inventory, Steve was considering returning the aircraft but the folks at Falcon stepped up and offered to send a free battery at no charge. Shortly thereafter Steve has a 45C Pulse Ultra battery in hand and is looking forward to flying his new airplane.

Today, Steve brought the DO-27 over and we started unpacking and assembling. Visually the airplane is striking with a nice paint scheme, quite a bit of scale detail and a very distinctive look. Packaging seemed to be excellent with no damage noted and everything held tightly in place. The model is also very complete with everything needed including a nice wood prop, spinner, nice looking wheels, etc… Assembly is very simple with only a few steps to complete but during the process we did note a couple of issues. Two were especially troublesome.

First, the front wing tube in the port side was impossible to install. It went in an inch or so and then became very stubborn. After forcing it a bit further it just continued to get more difficult to slide in. Visual inspection seemed to indicate the tube was misaligned with the plastic wing root as a lip can be seen on one side. With no way to move the tube (it seems to be quite securely installed) we tried using a drill bit to open up the entry to the tube and eventually managed to get the tube in place but it is very difficult to install and I think another call to Falcon is imminent!

Secondly, when Steve attempted to connect the linkage to the tail surfaces we quickly realized one was far to short and the other far to long! It was quickly decided that the linkages were simply swapped at the factory so we traded them out and things looked a bit more promising until we realized that both were now to long… a bit more head scratching and we realized that if we physically reversed the servos, essentially moving the output shaft forward a bit, we might have something that would work. With that done, we got to a workable linkage layout and all seems well.

Another minor issue was clearance between the landing gear blocks and the foam hatch that screws on over it. Once the straps were added to hold the landing gear in place, the belly hatch was held slightly away from the body of the plane. Some simple trimming in the area took care of the problem.

We still have high hopes that solutions to all the issues will be found and Steve will get to actually fly the bird soon. With any luck it will fly as good as it looks and we can leave the issues behind. More to come….

April 19, 2015

Lots of LiPos… maybe parallel charging is one answer?

I recently picked up a higher power charger… In my case, I chose the Revolectric FMA PL-6. This is a very highly regarded charger and I did not pick it for just the power but that was a basic requirement in the decision making process. So far, I am enjoying it and I will have another post up shortly with more info on that product. The important plot point for now is that this is a single output charger that can crank over 400W of charge power at 12V and over 800W at 24V. Compared to my previous chargers that have always (at most) been limited to 50W per output this thing is a real power house… but I was thinking I had to trade off quite a bit to get the big power. For instance…

The first big trade off when looking at these higher wattage chargers is that they typically have fewer outputs. On my old trustworthy Hitec X4 I have 4 outputs, each capable of 50W of charging power. When you start looking at chargers with 400W or so you usually get 1 output or occasionally 2 outputs with 200W of power each. By the time you get to 600W or higher you are typically going to get one output.

This was an acceptable trade off for me because my main goal in purchasing this charger was to allow me to charge my 6S 3300-4000mah LiPos in a reasonable time. A 4A charge (one hour recharge for the 4000s) at 25V (approx.) requires a 100W charger. With my 50W, charge times were in the range of 1.5-2 hours. With my new charger I can charge at 2C (8A) which at 25V is 200W and charge in 30 minutes or less. Not bad! In a pinch I can even charge faster as the batteries are rated for 5C (20A) max charge rate which would bring me to a 12 minute charge provided I have at least a 24V supply! I don’t like to push the batteries that hard normally but it’s nice to have that ability.

The problem, it would seem is that I now can only charge one battery at a time so if I charge at 2C or so I could charge another battery every 30 minutes. That’s great but it sure would be nice to be able to charge multiples… Oh well, I guess I have to give up something for progress… or do I! As it turns out there is a way to get there, and it really isn’t that difficult. Enter the parallel charging board…

2015-04-16 21.03.15

With this nifty little board plugged into the 6S balance port on the included balance board as well as the main charge ports of the PL6, I can now connect up to 6 similar batteries at a time and using the high power charging capabilities of this charger I can charge all 6 at once!! There are many versions of this board with various types of charge plugs, so be sure to get the version that is right for your batteries. It’s really fairly simple to use and quite effective. Basically as long as the batteries are all similar cell counts and are starting the charge cycle at fairly similar states of charge, you can simply plug all of them into the board (main charge lead first, then the balance plug from each battery) and you’re ready to charge.

As an example, let’s say I’ve flown 6 flights on my T28 using 3S 2200 mah LiPo batteries. Assuming I’ve run them all down near exhaustion I simply plug in the main leads and then the balance plugs to the balance board, set the charger for 2200mah charge rate as normal but specifying that I am charging 6 parallel batteries. The charger will then multiply the charge rate and start charging at 13.2A. In an hour or so, all 6 will be charged. If all the batteries can handle a 2C charge rate of 4.4A then we could charge them all in about 30 minutes as the charger would be pumping out 26.4A. 26.4A at 12V (all approximations) would require a bit over 300W which is easily attainable with even a fairly modest 12V power supply or battery.

There are a couple things to keep track of when parallel charging. You should take it seriously when I say that the batteries need to start the process at near similar charge levels. Any difference in voltage between the packs will equalize by current rushing from one pack to the other through whatever connections are available (thus the advice to connect the main load connectors first since they can handle more current). This rush of current if pretty much unrestricted and could overheat another battery or smoke the balance board if the difference is to great. Also, note that all the packs need to be of equal cell count so no mixing 3S and 6S etc…

When this really gets to be impressive is when you look at what happens if I want to charge up all six of my 6S batteries. I have 2 4000mah, 3 3300mah and 1 3700mah 6S packs for use in several of my planes. Using my old 50Wx4 charger getting all 6 packs back to charged state after a full day of flying would take at least one full charge cycle of 1.5 hours (at least) for the first four and an additional 1.5 (or more) hours for the second batch of 2. This is 3-4 hours of charging. Now, I can hook up all 6 packs in parallel and even if I pick a modest 3.3A charge rate the charger will then do the match and start charging at about 20A (assuming adequate DC power). The charge cycle will likely take only a bit over an hour and all 6 packs will be race ready again!

I’m not sure I’d want to do this with packs that were hugely different in capacity… have to think about what will happen and whether this might cause issues but I’m not concerned with this particular scenario. Of course parallel charging is possible with other chargers… this is not something only this charger can do… but to be useful the charger needs power to spare. Your average 50W charger need not apply… Here are links to both the charger and the balance board in case you are interested in purchasing one or both for yourself.

February 26, 2015March 13, 2015

“Wax” coating for foam airplanes…

As I have ventured into more Electric powered flight I have acquired more and more foam aircraft. Foamies are great as they are durable, easily repairable in most cases and very light. Foam is also easier for manufacturers to shape into all sorts of shapes and allows them to mold in a lot of intricate detail if desired. Sometimes the downside of foamies is that the foam tends to get dirt and dust embedded in it, grass stains and other scuff marks etc… As well, whatever paint has been applied often wears away quickly. That’s not a big deal when the plane is the $30 variety but as the foam and electric planes get bigger, more detailed, and more expensive, you tend to become more interested in preserving them. Even my T28, which is cheap at twice the cost (but don’t tell Parkzone) gets dirty and ugly far to fast in my opinion. I am on my third and have probably 1000 total flights on them, and wanted a way to protect the latest edition.

I have seen folks using a clear spray coating of either urethane or something similar but it can damage the foam (either the spray itself or sometimes the propellant used). As well, many of these eventually yellow and are hard to remove once that occurs. Looking for something better, I ran across some information recommending a coating of Pledge Future floor polish to help preserve the foam and whatever finish has been applied to it. I hunted a bit and found the product had since been renamed and re-marketed as Pledge Multi Surface Floor Cleaner so I went out an hunted down a bottle and first did a test coat on a scrap of foam with promising results.

I have since coated part of my FlyZone Tidewater and all of my Parkzone T28 with it and I have to say the surface seems to be quite tough and very slick and shiny. In both cases I covered the airplanes by simply painting it on with a foam brush but you really can’t tell that by looking at them. I have read that many folks have applied it with an air brush with great results as well but aside from giving you a thinner and lighter coating (which may be important to you if weight is a critical in your application), I don’t think you will be able to tell the difference in finish as the product seems to be self leveling in nature and I ended up with a very smooth, slick finish on both aircraft. Here’s a view of the T28… it may be hard to tell from this but the finish is much slicker now than it was before.

So aside from a small amount of weight there are a couple possible downsides to watch out for. As I learned first hand on the Tidewater, the paint on your foamy may be soluble by the coating! Yep, the paint on the Tidewater started running as soon as I applied the “Future”. So test first with a very small amount of finish in an unobtrusive spot before applying widely. With care, I did manage to coat all of the colored areas with a minimum of runs (a bit of dabbing with a paper towel works wonders). On the plus side the T28 finish had no issues at all.

Secondly, while the viscosity of the product (just a bit thicker than water) lends itself well to application via foam brush or airbrush, it also can run easily so apply lightly. The good news is a little reapplication will often soften the area and allow the aforementioned self leveling to occur. If worse comes to worse, ammonia based cleaners will take it off so you can start over! Keep this in mind while cleaning the aircraft in the future as many window type cleaners will contain ammonia and dull or remove the finish.

Based on my experience so far, I’m planning on having a buddy do a coat of Future with an air brush for my Carbon Z Cub. He has more experience with air brushing than I so once I do a little bit of customization/decoration I plan on handing it off to him for the actual application.

If you need to get some Pledge Multi Surface to try it out for yourself and can’t easily find it locally, here’s a link to Amazon for the correct product. Pledge Floor Care Multi-Surface Finish

It’s cheaper there than I found it locally, even with shipping! I’ll update this post with my experience once flying season is in full swing. Please comment with your own experience here as well.

December 28, 2014

Carbon Z Cub – First changes/modifications.

I’ve spent a fair amount of time scouring the forums and am currently up to about page 400 in the 1000+ page discussion of the E-Flite Carbon-Z cub on RC Groups. If you care to read all about it click here. Just to be clear, the cub doesn’t necessarily NEED any modification to fly well. It appears quite capable and fun to fly right out of the box but I’m one to “tweak” a bit on every plane in order to get a bit more out of the plane, increase the fun factor and hopefully the life of the airplane.

Using input from the discussion group and based on my own experience with this model as well as others, here are three areas where I’ve made changes to the airplane so far.

1. I continue to be disappointed with the paint. Just normal handling, battery insertion, etc.. has caused 3 or 4 areas of paint flaking off already. My first step in combating this was to head to the local home improvement store and get computer matched blue and gray, satin, interior house paint samples. Each is a half pint (probably a lifetime supply barring drying up) and cost is only about $3. It was suggested to take the two hatches in to have them computer matched… but of course I forgot and left them at home so had to find the pictures in the forum on my smart phone and have them mixed off the numbers on the labels that someone was kind enough to post. I suggest you do your own computer match instead as that has a better chance of exact matches to the paint on your cub but mine came out excellent… I was lucky. Using this paint I have already touched up 4 spots on the cub and other than a very small difference in “sheen” I’d say it is an excellent match. It does take two coats of blue to get the color perfect over bare foam. Also, it does look bright when you apply it but after drying it is a great match.

2. Bought and static tested an APC 15×6 E prop which has received some good reviews on line… Static tests indicate that a full charged stock E-Flite 3200 6S 30C pack with the stock 15×5.5 propeller is drawing 59 Amps right off charge. The cells sag to maybe 20V which equates to about 1200 Watts. 1200 Watts with a sub 9lb airframe equates to ~133 Watts per lb. For a cub… that is somewhere between high and rocket powered! In addition, 59 Amps is just under the 60A continuous rating of the speed controller and well under the 75A peak allowed so all is well with this setup. Static testing of the new APC propeller had it pulling only 54 Amps. Flight testing and perhaps some static thrust measurements will be interesting. If the APC can produce as much thrust as the stock setup and use less amps it would prove that it is simply a more efficient airfoil… If it does not produce equal or better power than I may stay with the stock prop for at least a while longer. Stay tuned on this one. Propellers are often a quick and easy upgrade and this test so far proves that you cannot use diameter and pitch measurements to compare propellers across brands. The airfoil design is key and the listed measurements from the manufacturer are to be taken with a grain of salt.

3. I purchased some DuBro 6″ inflatable tires to replace to stock foam tires. The stock tires are considered by most to be acceptable for grass fields only. I don’t even really like them on grass as they seem to have almost zero cushioning capability and the heavy wire landing gear is mounted into foam and plastic which seems like a possible weak spot. In order to protect that mounting, I am going to try the DuBro wheels with minimal air pressure. They are almost 3/4 of a pound heavier than stock so I will lose a little power/weight ratio but I can compensate somewhat by keeping to smaller battery packs (folks are running up to 5500 mah packs… so far I’m staying with 3300-3700).

I’m considering quite a few other additions, modifications, updates, etc. that I’ll discuss as I decide on and implement them. Most likely there will be telemetry installed as well as some personalization of the color scheme, flap/elevator mix testing, and more.

Right now I’m getting prepared to go flying on new years day which is currently being predicted to be a balmy 20-25 degrees(F) and 10-15mph winds… First to explore is whether I can get the Cub into the trailer fully assembled to avoid freezing fingers having to assemble in the cold!

December 28, 2014

Blade Nano QX – Adding Nav lights.

December 20, 2014March 13, 2015

Hitec X4 Micro AC/DC 1 cell LiPo charger

I have taken to doing some indoor flying over the past couple of winter seasons as the bitter cold and snow of Indiana this time of year is not particularly conducive to just hanging out at the field. It’s a lot of fun, but is yet another specialized endeavor within RC which means there is some specialized gear available to help you get the most out of your time spent. I.E. More toys!!

For instance, most of the small indoor aircraft use a single cell LiPo in the 30-200mah range and tend to eat up those precious little milli-amps in a short 4-8 minute flight. That means over the course of a 3 hour indoor session you can run down a BUNCH of batteries. I tend to take some pictures, talk with the other pilots about their aircraft and find other ways to distract myself for much of the time but I can still run short of charged batteries in a hurry. This is especially true when flying a little quad that can use up a battery in 4 minutes. Along with buying ever more batteries, I’m doing a fair amount of recharging at the gym.

At first, just using the single chargers that come with many of these airplanes was OK, but those chargers can be slow, are sometimes bulky and they either have to plug-in to an AC outlet or run off AA batteries depending on the whim of the manufacturer. It’s easy to end up with nearly dead AAs inside those chargers at the worst time and there is never enough space on my 2 wheel cart going in and out of the gym so my array of 4 single cell chargers (powered by 16 rechargable AAs) had to go!

At first my solution was simple. I have a couple of buddies who each have one of the Thunder Power Quad Port AC/DC chargers. I would just borrow a charge port or two from my flying buddies!! This works alright and they don’t mind sharing (not much anyway) but there were never enough charge slots available and I was hoping for something a bit better. I tried to drop hints that those guys needed to upgrade their chargers but I’m the gadget guy of the bunch… I like buttons and switches (if they serve a purpose) and they were happy with the simplistic but effective little Thunder Power. Here is the little TP with a link to see it on Amazon.

Thunder Power Quad Port Charger

After a little research on the web, I decided to pick up the Hitec X4 Micro. At a bit over $50 it’s a bit more expensive than the TP but it has several nice features.

X4 Micro AC/DC 1C LiPo Charger <- Click here to see/purchase this on Amazon

The Hitec can not only charge 4 batteries simultaneously at anything from .1 to 1 A rates, but it has a separate LED display for each of the four charge circuits so you can tell what is going on with all 4 with a glance. To charge just plug in to any of the 4 sockets as appropriate for your battery connector type, dial up the rate you’d like to charge and push down and hold the red start/stop button for a few seconds (until the led lights solid and you hear a longer beep) and you are charging. If you just momentarily tap the button before charging you will be shown the current cell voltage (and hear a short beep). During charging the display sequences through showing you the current charge rate, the current cell voltage and the amount of charge taken (in ma). When the charge is complete you are treated to a green light along with a series of 5 beeps and the word FULL on the screen. This alone may be worth the price of admission for some. One of my flying buddies is effectively red/green color blind so you can imagine that seeing FULL displayed might be more helpful for him than just a red or green LED. With FULL displayed you can tap the button again and get a cycling display showing the end voltage, the total milliamps provided to the battery during the charge cycle and the FULL display. With AC or DC input options, along with an AC cord and DC connection with alligator clips all supplied, this little charger is at home and ready to work on the bench or at the gym.

While the Thunder Power is a fine little charger (and it is much smaller than the Hitec which can be an important plot point) it can’t compete in my mind because of what for me are the two big pluses afforded by the Hitec. First is the array of information available to me when using the Hitec. The TP just tells me charged or not via the red/green LED. The Hitec keeps me informed from start to finish. Secondly is the ability to control the charge rate. This is handy in both protecting my batteries from being “beat up” by a to high charge rate and to take advantage of faster charge rates when I want to based on the capability of the battery under charge. Most of the little 1 cell chargers do so at a fixed rate… in the case of the TP for instance .3A… period. Want to charge your 30mah cell? Hope it likes to charge at 10C cause that is what it is going to get. Fast but brutal!! How about your 200mah? You guessed it, .3A and I hope you aren’t in a big hurry cause it’s going to take 40 minutes or so. Don’t get me wrong, chargers like the TP are fairly inexpensive (Around $35 at the moment) and work pretty well for most applications, but I like to have more control over the charge process and know a little more about what is taking place. With the Hitec I can charge my 150mah E-Flite at it’s max charge rate of 3C (450ma) for a quick 20 minute charge when I really want to get back in the air fast but when the session is over and I’m back on the bench getting things ready for the next fly, I can just as easily drop down to a leisurely 150ma 1 hour charge.

I will say that the Hitec does require you understand a bit more of what you are doing in order to be used correctly. You have to pay attention and set the charge current accurately to get maximum benefit from the box (easy to do with the display and just a little knowledge). In my book that’s just another part of the hobby and one I enjoy actually so this is my kind of tool and for $50 I think the price is reasonable.

The other price you pay for the extra features of the Hitec is a little bit of bulk. The Hitec is pretty compact for what it can do (especially for an AC or DC unit) but your not going to stick it in your shirt pocket either. Still compared to the single cell units I was using this will take up the same space as one, and do the work of 4 so all in all I expect this thing is going to work out well for the intended job. I’ll update as I get more experience if anything changes my mind but at the moment I’m thinking the Hitec X4 Micro is a keeper.

December 16, 2014December 20, 2014

E-Flite Carbon Z Cub – First flight and glider tow!

After waiting for the warmest temps of the day to arrive (while watching my favorite NFL team squeak out another win) I and my buddy Steve headed to the field to get a first flight on the Carbon Z. We had about an hour of daylight left with temps in the mid 40s and a mild 5-10mph wind mostly down the runway to work with when we got to the flying field. For early winter in these parts, about as good as it gets.

Assembling the cub in the cool weather was a bit chilling but not overly difficult or time consuming. If you have to have struts, these aren’t to bad to put in place. First order of business was to make a short hop to check trim and dynamic balance and overall just get a feel for how the Carbon Z would fly. The result? Pretty much as expected. The big Cub found the sky very quickly before I had gotten much past 1/3rd throttle! Subsequent takeoffs were found to be possible in about 4 feet… and that is without use of the flaps.

With only a couple clicks of trim, the cub flew nicely. Using the wing and somewhat less control throw than recommend even for “low” settings in the manual, the cub was immediately discovered to be more capable than any cub I’ve ever flown or even seen flown. Power was adequate for nearly unlimited 90 degree vertical climbs, continuous knife edge, 20 foot diameter loops, rolls, stall turns, etc… No problem. After 3 minutes or so, a nice, gentle main wheels only landing was accomplished. We quickly then rigged up my friends brand new KA-8 glider and with a very smooth mid-power climb he was hauled up to about 250 feet where he successfully released and began floating around the field. The cub was brought in for a quick landing so I could watch Steve’s KA-8 floating about and then making a near perfect “spoilers” landing within 20′ of where we stood. Nice job on the first flight Steve!

After clearing the tow line and moving the glider away, Steve took the Cub up for a quick spin and commented immediately on the ample power and stability of the Carbon Z. After a few minutes of fun, Steve brought the big bird down for nice landing of his own.

Before the light could totally fail, I took the bird up for one more flight. First, I climbed up to a safe altitude and tried deploying the flaps. The resultant pitch up was fairly dramatic, and that was with the lesser of two flap settings I had programmed. That will require some more research and programming! Pushing the envelope a bit further I started through the basic IMAC sequence as best I could recall from earlier this year. The Cub seemed to be doing fine with the maneuvers until the motor started to pulse and it was time to come in for another easy landing. Altogether, I had been above 10% throttle for about 13 minutes. Better than I expected for the 3300mah pack, especially in cool weather.

Even though the Cub landed very gently, I do want to get some softer wheels for those times when something slightly more harsh occurs and the flap mix and travel are going to require some more adjustment and testing. As well, I will be getting some more batteries of somewhat varying size and brand. I think the cub could easily handle somewhat larger cells and I wouldn’t mind to have a bit more flight time per pack. With a safety margin, the 3300s would appear to give me a solid 10 minutes of more aggressive or maybe 12 of pure cruising. I’m guessing this might translate to only 2 or 3 glider tow climbs and in this mode I really would like to have to stretch that to 4 or 5. Once I have some more batteries in hand I can do some test flights and see what sort of trade off between capacity and weight is possible.

Overall, after one battery (3 short flights) I can already tell the big cub is going to be a lot of fun. I’m looking forward to getting her out at the next club event (the Freeze Fly on January 1st). With these bug tundra style tires, even a little snow shouldn’t present a problem. And if the snow gets deep… the floats are sitting in the box out in the shop.

December 16, 2014December 20, 2014

E-Flite Carbon-Z Cub… Modifications and Setup

With cold weather and rain the rule for the first few days after the initial assembly of the CZ Cub I turned to setting up my radio and adding one or two “upgrades”.

First up, I went through and put triple rate control throws and levels of expo on my radio. Also I set up for a stopwatch timer as I am unsure of the flight times I can get from the recommended Eflite 30C 5S 3200mah battery I purchased. From there I setup the flap system with a nice slow 2 second deployment and 20 percent of down elevator throw. Unfortunately with no indication of how much Flap throw is considered normal there is no way to know how much flap or how much elevator mix will be required to offset it. The manual says 42% of elevator but that is hardly helpful with no idea of 42% of what!

Continuing on, I had read some forums that indicated that the paint around the front hatch was prone to damage due to trying to get hands and batteries in and out and that a new battery tray that was laser cut helped with this issue. I decided that this made some sense so I ordered the Morgan Mills RC battery cartridge system and installed it. Assembly was easy once I viewed the assembly video on line about 3 times! If you don’t do that, good luck as there are NO included instructions!! The tray and cartridge seem very nice so far and definitely make getting batteries in and out easier. This is the part that replaces the plastic tray inside the airplane.

And this is the battery holder that you put the battery in before insertion into the airplane. I added the small rubber dots you see to keep the pack from sliding even the small bit that is allowed by the tray. I also used my own double sided industrial strength Velcro instead of the stuff that came in the airplane (it seems a bit weak when you consider how heavy the battery is that your securing).

So far, playing on the bench, it seems to work very nicely and the ability to easily reposition a battery to exactly the same spot every time you put it in the plane is certainly going to help, especially if you plan on running more than one size/weight pack (like I likely will).

The downside of all this is that folks are right on when they say the paint in this area is fragile. In fact, I think it is pitiful… Even being aware of the issue and trying to take great care, I have already lost a fair amount of paint in this area before I’ve even made my first flight. This is very disappointing… I realize this is a foamie but it’s a fairly expensive foamie (not the original cost so much as the total investment) and there’s got to be a better way to get the paint to stick to this foam. It really worries me as to how well the rest of the paint is going to hold up. My investment at this point with battery, receiver, plane, floats, and glider release servos is over $600. I’d like to have this thing look decent for more than the first 2 weeks! I was thinking the overall price on the CZ Cub was pretty nice for this large a plane… foam or not… but I was expecting to keep the paint attached for more than a few days. Very disappointing even if it is only cosmetic. Here is a close up shot showing what has already occurred in just a few days.

Next I went to install the glider tow release servo. I love that the CZ Cub has this built in with only a servo needed to make it operational. I have two buddies who would love to have a good tow ship available to get their gliders aloft and this thing could be just the ticket! I wish the instructions were a bit clearer… or maybe just a better diagram but the actual mounting point looks a bit different than the diagram with no direction given as to what type of screw to use to mount the servo… at least E-Flite is consistent! In actual practice I ended up using one screw through the servo mounting hole on the servo and another just overlaps the end of the servo mounting tab and clamps it in place. It seems very strange but seems to work so far.

At this point I am ready to fly and while I am trying to tamp down my expectations I really am expecting some good performance. The plane only weighs 8.5lbs ready to fly at this point and with the 6S power, flaps and huge wing area it should be a real floater with some excellent power to weight ratio. Can’t wait to fly!