Fly RC

December 23, 2015December 26, 2015

Balsa USA 1/4 Scale Cub – Part 2 Modifications begin

I’ve spent a fair amount of time just sitting and staring at… by which I of course mean meticulously planning modifications for… the Balsa USA Cub. I have been comparing the J-3 Cub and the PA-18 Super Cub from a visual appearance perspective and one of the first things I realized is that the Super has a slightly different shape to both vertical and horizontal components of the tail surfaces. Looking at the horizontal feathers first, there is a bit of a difference in shape, especially in that the PA-18 has what I refer to as aerodynamic load balancing. In the case of the Super there is a section of the elevator that is in front of the hinge line located at the most outer section of the elevator on each side. This design not only give you increased surface but also decreased load on the servo as the air flow on that part of the elevator will aid in moving the surface in the desired direction. I.E. When you pull elevator the rearmost part of the surface goes up relative to the hinge line and the airflow is fighting this motion which your servo must overcome. The part forward of the hinge line however is moving downward and the air pushing on it is helping to rotate the surface and therefore is assisting the desired motion! This is not only a very noticeable difference visually in the control surface shape and design but it is one that will help to keep the servo(s) on the elevator from having to work so hard! I like that so I immediately decided to incorporate this change. Another nice part of this modification is that it is simple since there is a rib at approximately the correct spot where surgery will need to be performed to make this change!

Of course the horizontal surface is also a bit different shape on the Super versus the standard cub. I haven’t decided if I will do anything to correct that as it would be purely cosmetic… adding very little surface area to the elevator… We shall see. So here is what I did for this first control surface change.

Here is the starboard horizontal surface.

That first rib looks to be in approximately the correct spot so below you can see the first cut has been made right against that rib. Plenty of TLAR involved in this project!

After making this “incision” I then needed to add a rib to the tip of the fixed surface. If I just capped them with a piece of balsa I’d end up with a fixed surface that would be to wide for my elevator to wrap around so I then had to cut off about 5/16ths worth of balsa in order allow for insertion of a new 1/4″ rib (1/4″ x 3/8″ was used as the thickness of the trailing edge is more than 1/4″).

I then installed my new end cap as seen below

And after a bit of sanding to size I ended up with this

Rinse and repeat for the other end and I am ready to glue the removed part to the moving elevator surface. The builder has done very little shaping of the leading edge surface of the elevator so I think I can glue the removed portion of the fixed surface to the front edge of the moving portion and with just a bit of filling and sanding I should be all set.

I will probably leave the tail surfaces for a bit and work on the wings next as I am in the mood to tackle that project. I’ve been getting nervous about cutting into the wing surfaces for a bit and I think I have my courage screwed up now since this task came off fairly painlessly. I’ll get back to the tail surfaces again and see what can be done to shape up the rudder a bit later.

I have yet to decide if I’m going to do anything else on the elevator before I call that part good and move on but for now I am pleased with my progress. There is at least one big “mistake” that the original builder made that will prohibit me from making this plane truly scale looking… at least it’s a big enough discrepancy that I don’t think I will tackle it. Once I decided that it made me start considering what the limits are going to be in terms of how much effort I am willing to put into this thing. I feel his pain as I have problems when building sometimes telling my left from my right as well but I’m not going to point it out yet. Maybe you can try to spot it someday when the project is finished and I get it ready to fly and take a few photos to post here. It’s nothing that will effect the flight performance of the airplane but there’s no way this thing will ever be in a scale contest! As a result, there is a fuzzy line in the sand in regards to how far I’ll go to make it scale. I want it to be recognizable as a super cub and even as a particular airplane but I’m not going to get to crazy making it perfect. I’m especially leaning toward anything that not only makes it look more Super and less J-3… especially when that affects it’s flying characteristics as well. I guess it’s just going to be Goldilocks scale. Not to much. Not to little. Just right!

December 22, 2015

Balsa USA 1/4 Scale Cub – Part 1 Acquisition and plans

Recently my club had a batch of RC gear contributed and much of it was sold off to club members over the course of a few weeks with proceeds going to the club. One of the items that got sold off was a Balsa USA 1/4 scale Cub. The kit had been almost completely framed up and even some covering done. The craftsmanship looked good and the price was right so I decided it would be my next large scale electric project. I have immensely enjoyed flying my 84″ wingspan Carbon Z Cub and I figured 108″ of Cub might mean almost 30% more fun!

It also seems like a great excuse to try something with an even larger electric motor and with it in the 90% framed up state, I figured it was ideal to do some “bashing” and make it into something a bit different than the usual “big yellow cub”.

I searched for a suitable subject and came across several attractive options. I needed to balance the desire for something a bit more unique with a practical eye toward ease of adaptation and availability of covering options etc… I didn’t want to go to the level of scale competition but I wanted something recognizable as “not” an available ARF. I looked at the NE-1, the Grasshopper (complete with Bazookas) and a couple others before I settled on a conversion to a PA-18 Super Cub.

There are a number of color schemes that are close enough to available covering colors to make it unnecessary to resort to painting… and many variations of the Super Cub exist… So many of these aircraft have been modified “in the field” that it would be difficult for anyone to point out a combination of “optional” gear like tire size, window size and shapes, cowl changes to accommodate various motors, etc… etc… that isn’t out there somewhere! The one’s that attract me most are all bush planes with the big tundra style tires! Those things not only add a nice scale touch but they are practical in that they absorb a bit of the abuse that the air frame would normally have to absorb.

Super Cub cowls are available for this kit so that part of the profile is easy to achieve. Bush wheels are also available as are light kits, interiors, articulated landing gears, etc… etc… So a bush variation PA-18 is what I will shoot for. I picked a picture off the internet of an Alaska based aircraft that I thought would be “within reach” to model and started planning, plotting and modifying.

First on the agenda was gathering info on equipment I would have to acquire. Bush tires and a nice shock absorbing landing gear are a necessity and I found PR bush wheels… These guys are out of Alaska and they created scale bush tires and rims for several sized and types of Cubs because no one else really has another really good option that I could find!! You really need to check out their video of a customer doing wheels skims across a pond! They are pricey as one would expect for such custom items but one of my flying buddies stepped up and ordered me a set in return for some RC shop work I had done for him recently. I wasn’t looking for that kind of payback but it is appreciated! Thanks Kelly!

Of course this forced me to order the appropriate Robart 1/4 Scale Cub landing gear! Can’t have those fancy wheels on some old, ugly wire gear can I?? So now I have pretty much all I will need to have an awesome landing gear setup for the PA-18.

Here’s the Robart gear with the wheels attached… These are going to look great!

I also went ahead and order a new cowl from Fiberglass Specialties Inc… They have a stock PA-18 cowl that fits the Balsa USA kit. It looks to be their standard quality workmanship (which is high) that has already survived sever drops from my workbench onto the concrete floor with nary a crack. I really need to quit dropping it!!

The project has since languished a bit as work got busy and I spent some time working on other projects. I also had to spend some time stuffing the piggy bank to purchase a suitable motor, speed controller, etc… I have finally gotten back to doing a bit of work on the Super Cub and I have found a few more things I felt “needed” modifications. There are a number of noticeable differences between the venerable J-3 and the PA-18.

I have the cowl taken care of but the tail feathers are noticeably different with aerodynamic counter balances on the elevator and a more rounded and larger rudder as well as some obvious bracing difference in the cockpit. Also, the vast majority of PA-18s have flaps while the majority of J-3s do NOT. Those items seemed to be high on the list of what makes a PA-18 look different and they all seem to be modifications that are “in reach” since they will require very little but time and effort to accomplish.

During this busy time I started stripping all of the covering off of the control surfaces and a bit of the tail which was about as much as the gentleman had gotten to. This was mostly accomplished during short windows in the shop after work was finally done and before bedtime.

I also removed the glow motor mount that I won’t be needing… The blind nuts I punched out before I realized that the top pair were trapped in an enclosed space and now make a fantastic rattle! I can see some Dremel work is coming to retrieve those!

This promises to be a fun project so I will have more updates soon as I expect to get in the shop a bit over the next 2 weeks around the holidays. I’ve already made some progress on the cockpit area, tail surface shapes and flaps so will try to post on some of that soon.

December 4, 2015December 4, 2015

Conversion of the Telemaster 40 to Electric Power – Part 2

It has been a while and my job keeps getting in the way of having fun… but I’ve finally started making progress again on the Telemaster conversion to electric power. Here’s some updated photos…

First you can see here the body with the transparent yellow Ultracoat applied to the open areas of the body. Basic white on the areas that are solid balsa/plywood or sheeting. That’s my basic theme with the addition of some white on leading edges and wingtips. Sort of a “visual airplane” so folks can see what is inside… I guess I’ll have to keep it neat inside when I go to install the servos etc…!!

Inside I installed a couple rails to mount the speed controller and a shelf in the bottom to give the battery a secure place to rest. I’ll add some velcro straps later. Here’s a view from the wing saddle area looking forward.

2015-03-14 12.57.04

Here’s some closeups of the modifications to the forward hatch. I needed some airflow over the Castle Creations Talon 90 speed controller and the expected 6S battery! If you look closely up above, you can see where I opened up a triangle on each side of the fuse for air to exit the fuse. With this forced air inlet I’m hoping to keep everything cool.

Essentially I just cut a piece out of a plastic soda bottle that looked vaguely “scoop” shaped and then traced around it on the hatch and hacked away the opening with a sharp Xacto. I added the forward brace to keep this all balsa hatch stiff and then used med/thick CA to hold it all in place. Adding some covering and a little rubber “combing” to the front edge later makes it all look pretty good!

Following the pattern already established I tackled the stabilizer area… solid vertical gets white and horizontal the transparent treatment. White adds a nice touch on the tips and leading edge plus helps seal it all up. That vertical will make a nice place for some added detail later… lettering, stripes, decals or whatever suits my fancy.

I’ve also been working on the wing to make the assembly easier. No more rubber band wing attachment!! Now 4 bolts will hold the wing in place. Less room for error perhaps but so much easier to get ready to fly and no re-trimming due to alignment of the wing variance.

Here is the wing center area.

As you see I cut into the top of the wing just behind the leading edge and installed some beefy plywood to give me a strong and flat surface to bolt to. Its epoxied to ribs on both sides and the bottom sheeting so I don’t think it’s going anywhere. In the back you can see the little wedge shaped hardwood blocks I cut and sanded to size then epoxied to the existing hardwood plate on top of the wing.

Here is the saddle area of the fuselage.

At the right you can see the plywood plate I installed in the forward fuselage area. It sits right under one of the main longerons and epoxy is again used to secure to the front bulkhead, fuselage sides and longerons. In the rear are some commercially made plastic bolt on inserts that have nice tight 1/4-20 threads cut in them. I can’t recall who made them but I had them laying around so I went that way rather than do another plywood insert. Due to the light construction of this aircraft there is no hardwood in the wing saddle area in the original design but since the aircraft is so light, I’m hoping these will hold without any more reinforcement. If I see play developing I may have to reinforce later. I’ll keep a sharp eye on it!

Some of you eagle eyed types may have noticed that my front bolt holes are not exactly “exact”! When I drilled those through the wing and down into these plates my trusty TLAR method (That Looks About Right) allowed for a bit of drill bit wander. I was concentrating on making the holes straight up and down so the bolt heads would sit nice and flat on the plywood and didn’t notice the discrepancy. I don’t think it really matters… the idea is to be secure, right! I’m pretty sure no will notice as it floats by at 20′ altitude and 20 mph.

That about covers the last few months of progress! I expect to get some more significant work done over the holidays… or maybe not as I have two other (or is it 3 or 4 or …) projects laying around I want to get back to as well. Oh, and there are 3 or 4 guys that have some winter projects they want to bring over… Which ever project or projects get some bench time, I’ll try to update here. Looking forward to any suggestions or comments you all might have. Feel free to post below.

October 29, 2015October 29, 2015

Throttle lock/Kill Switch programming on the DX8

A couple years ago I was taxiing back toward the pits with one of my smaller gas powered planes and had stopped to observer another flyer doing a nice touch and go… My plane was sitting by my feet at a sedate idle during this distraction. When I turned back, I returned my left hand to my radio and inadvertently slid the throttle stick to full!! Luckily I was pointed at the pit chain link fence 6 feet away with no other obstructions… like people… so as I grabbed the stick and returned the throttle to idle the plane made a dash for the fence and quit as a result of the impact and the prop breaking into several pieces. It did no real harm to anything except the prop and my pride… but it woke me up and from then on I have been much more attentive to my models while they are running. When I am idleing, my thumb is hooked across the top of the throttle stick so that it cannot easily be moved upward. As well, I now have a kill switch on every fuel powered airplane and it is always in the same position on the radio so I don’t have to hunt for it! With gas planes I have a mechanism hooked into the ignition circuit that kills power to the ignition. Depending on the type of engine and ignition system it may work a bit differently but each disables the ignition which kills a gas motor immediately.

With the advent of more electrics in my fleet this became even more problematic. Electrics, once the battery is connected, should be considered to be “running” in all cases and therefore treated with the respect that would be due any idling engine. Since you can forget the battery is plugged in at times, I try to be especially careful to restrain my electric powered aircraft whenever I’m not holding on to them and a battery is installed. I have also setup a throttle cut switch that limits the throttle channel output to zero or as close as possible. In some radios this is simpler than others. In my Spektrum DX-8 there are two ways to accomplish this… maybe more… but I’ll show one of them here that I use most. (I believe the 7s, 9 and 18 all do it similarly)

Note: You can do all of the following without the plane even being present and certainly don’t want to play with this with the plane powered up! I highly recommend you test after you finish however with the plane well restrained or the prop removed.

First, the DX-8 has a throttle cut option in the setup menu. If you go into that menu and change the inhibit to a switch label (I tend to use Gear0 as I’ll show below) you get a screen that looks like this.

You’ll notice that the switch is set to Gear0 (that’s a zero). I use this setting as I tend to setup my radio so that starting point for all airplanes when I fuel up or attach a battery is with all switches pushed away from me. It really doesn’t matter which way you do it. I’ve worked with computers and electronics so long and the way I was taught logic you generally consider 0 to be off and 1 to be on…. I guess position 2 is “really on” in the case of a 3 position switch!

With my radio set this way the throttle is locked so it cannot inadvertently start up without moving both the throttle stick and moving the gear switch out of its starting “safe” position. The other thing you may notice is that the position reads 30%. I played with this and came upon this setting by trial and error. I believe this has to be done because of two factors. First, the designers created this for (I believe) primarily fuel powered aircraft where the stop/kill position is significantly different from the idle/standard starting position. In an electric aircraft you generally don’t want an “idle” with the prop moving when you pull back to the lowest position on your stick. You want a full stop. Second, most speed controllers in my experience will look at the throttle setting on power up (as long as it’s at least somewhere near one end of travel or the other) to be the zero/stop point. That’s fine until you combine with point 1.

So imagine you plug in the battery with the throttle 30% lower than “idle”… which is what the throttle position would be if you left that setting at zero and had the switch pushed forward/off when you plugged it in. All seems fine… Your speed controller makes its little tunes and if you move the throttle stick nothing happens but your servos are energized (this may vary by manufacturer of the speed control). Great, you are ready to taxi and you flip the switch to the armed/on position and immediately the prop spins to a “high idle” setting!!! That’s not convenient, nor especially safe. This is because with the kill switch in the forward/off position the throttle was at a point 30% or so below the idle point and when you plugged in the controller reset that to be “zero”. By testing I have found 30% to be about the right point to avoid this issue. Now the kill switch doesn’t really change the position of the throttle at all and acts more like a throttle hold then a cut. Ideal for what we want when dealing with electrics.

There are other ways and other radios do it differently. On my DX-18 which I fly more than anything else I use the F switch instead of gear because I use the gear for other things… like retractable gears! But whichever switch you use, I suggest you keep it consistent. This way your routine on each plane is the same at least as regards to a safe “startup” and also because occasionally you may want to hit it in a hurry and not having to think about which switch it is can make a big difference in response time.

I’ll try to post on a different method in the near future. Hope this is helpful. Fly safe!

October 24, 2015October 29, 2015

Updates… Carbon Cub motor, AR9000 repair

In an earlier post I related my misfortune with my Carbon Cub motor having failed. Another covered the issue of channel cross interference in a Spektrum receiver. Well I’m happy to report that both issues are now resolved.

The Carbon Cub motor was replaced with no charge by Horizon Hobby. In fact it came back in something like 4 days which allowed me to get a test flight in at the club field before slapping the floats on and making a trip back down to Lake Lemon near Bloomington, IN for the fall float fly. Once again the Cub performed great.

I would still recommend the Carbon Cub, but I would certainly advise keeping a close eye on the BL52 motor from E-flite. I love the Power 60 on my Extra 260 but this motor is not that same quality in my opinion.

On the receiver, once again Horizon finally came through, and not only replaced but upgraded me to a new AR9020 DSMX receiver. I was a tad disappointed the tech still couldn’t recreate the issue after I sent them a video and exact transmitter settings that allowed me to recreate the issue using both my Spectrum radios! The important thing I suppose is they did right by the customer and that seems to be the way they tend to operate which is not always the case with all businesses. Kudos to Horizon on that front.

It’s getting to be late in the flying season here so expect to see some building projects, indoor/micro electrics and similar discussion soon.

October 1, 2015October 2, 2015

Carbon Cub – Motor problems!!

I bought my cub back in late 2014 and started flying it more as the weather got warmer here in Indiana. It has become my go to flyer and I probably have 100 flights or so on it by now. Unfortunately, yesterday it got put out of action by motor problems.

There have been 5 of the Carbon Cubs in the local club.

Cub #1 was sold as the pilot and the plane just didn’t get along… he could never get his to fly the way he wanted. Just not his style I suppose. I saw it flying at an event at another club this last weekend. Doing great on floats and seeming to have no issues as all.
Cub #2 is still in action but doesn’t get much flying as the pilot has other aircraft he flies more often. It had a motor issue within the first 20 flights or so and Horizon took care of it. The new motor has only a few flights on it since being replaced.
Cub #3 crashed within the first dozen flights or so with smoke issuing from it mid-flight and a burned up ESC and Motor apparent upon inspection after the crash. The airplane was heavily damaged in the crash. That motor was dragging badly and apparently drew so much current it fried the ESC. Owner of Cub #2 heard the engine grinding just before Cub #3 malfunctioned but didn’t even get time to speak up before the smoke started and it was all over.
Cub #4 had what appears to have been an ESC issue but I have not heard exactly what occurred. I just know it crashed and is out of service for the time being. It was flown pretty hard… this guy is a 3D pilot and he flew it that way. Nothing wrong with that but it may have played a part in its demise.
Cub #5 is mine. It has been flown a lot, but well treated and nothing happened recently that I would have expected to cause motor issues. I have not flown it exceptionally hard, had a nose impact or done much of anything unusual. Flew on floats a few days before, in heavy wind a day before that… Last flight was a long climb at mid-throttle using the wind to climb to near 1500′ AGL then a lazy dive punctuated with some spins down to about 100 feet. Probably not as hard on it as my glider tows to 1000′ or so that I’ve done in the past. When I pulled out to level and throttled up a bit I could hear the grinding and tried to limit throttle usage as I made a quick landing. I can see that several magnets have moved toward the rear of the motor and there is some gray residue inside the battery compartment where the airflow carried the shavings. I will clean that up and hope for the best regarding the rest of the electronics that are in the path of the airflow!

That makes 3 (maybe 4) of the 5 local Carbon Z Cubs that have had a similar issue. Horizon took excellent care of the owner of Cub 2 with a new motor sent out quickly. Cub 3 was replaced after the owner sent it back in for diagnosis. Not sure about the other one. My motor is on the way back to them now. I’m hoping this isn’t a representative sampling of the failure rates for these motors. I have read about a few folks on the discussion groups having these same issues. If Horizon takes care of me the way they have these other guys, I guess I would still recommend the plane to others but I will definitely tell folks to keep an eye on the motor. A failure at the wrong time could certainly ruin your day!

I’ll update when I hear back from Horizon. Hoping for a quick turn around… it’s less than 2 week’s ’till the next float fly!!

September 27, 2015September 27, 2015

ElectroDynamics Multi-Connex… The answer for the Carbon-Z T-28 and many others.

After a few trips to the field with my buddy Kelly and his new Carbon Z T-28 we quickly became aware that assembly was a bit painful because of the number of servo wires that must be connected when attaching the wing and the shortness of the wires supplied in the T-28. The length of the wires can be easily fixed but just connecting the 6 wires correctly and reliably time after time seemed an unnecessary annoyance to get to what the Carbon-Z does great… fly!

Another club member pointed out some multi-pin connectors often used in jets and after some quick searches we located the ElectroDynamics OneClik Multi-Connex. Made for 2,3,4 and 5 servos connections these seemed to fit the bill so we placed an order. Very shortly (even though we chose the most economical shipping method) we had two of these packs on the bench.

Here’s the interior of the T-28 before we applied the OneClik solution.

and likewise here is the wing root before the installation.

Here is the wing root after just sorting out the wires and plugging them in (in alphabetical order just for ease of remembering!) to the new One-Clik wiring harness.

Similarly the interior of the fuselage (with a little wire combing to really clean things up as well).

I applied a bit of combing to the wing wires as well and then with only two connectors to feed through the bottom of the fuselage it is suddenly very easy to assemble the T-28! A bit of Velcro (just a 1/4″ square of so on the connector and a small strip on the sidewalls) makes a nice “keeper” for the new connectors and completes the transformation!

Admittedly, it helps that the T28 uses all “Y” connectors so there is no right or wrong for left or right sides so you can’t connect it wrong but for those that don’t… at least you’d only have to label right and left!!

The product has a nice snug fit, a great positive click connection and appears to be of a very high quality. The pricing seems very reasonable and my only regret is that I didn’t order some of these for my Mustang! Oh well, even with shipping these seem to be a bargain.

Since installing these, we have made a couple trips to the field and unlike previous trips, the setup time is less and we have not had a miss-connect (pretty much impossible now). In the past this was a tedious task which has occasionally resulted in having to pull the wing and find an errant wire. I think that is likely in the past.

This system will likely become one of my go to upgrades for all future multi-servo wing aircraft. The ease of use and added security of the connection is a huge plus in my opinion and I highly recommend you give these a shot especially in those larger and more complicated craft like warbirds and the like with flaps, lights, and etc…

September 9, 2015

Battery Energy Sensor…

I recently got my hands on what seemed to be one of the first batch of the new Spektrum SPMA9605… known as the Flight Pack Battery Energy Sensor. Where the earlier options had been a current sensor and a voltage sensing lead, the new sensor promised to not only read instantaneous current, but to keep accumulated current draw and pack temperature as well.

I installed it into my AeroWorks Extra 260 (60-90 size) powered by a Power 60 E-Flite motor by the expedient method of simply plugging in the two EC-3s and the xbus connector from the earlier installed current sensor. Upon testing I was dismayed to find I could see no option to display the new information… Only after fussing with it at the field for 30 minutes or so did I recall that I had declined to upgrade the software in my DX-18 months before, seeing no need for any of the fixes that centered mostly on helis and sail planes. I especially did not want to rebind all of my aircraft since every previous version had required that. The latest versions promise that it might not be necessary but I had not been interested in testing that assertion.

A couple days later (tonight in fact) I downloaded the latest version and after backing up the DX-18s memories… placed the updated file on the memory card and hit the proper keys… After a couple of minutes the radio finished the process and miraculously upon power up, I had full control of the little Extra!

Even better, I now had the option to include the battery pack sensor in my display and set thresholds and alarms. I set up appropriate levels and tested the current readings and all looked promising. Since my built in temperature sensor was already in use monitoring the motor, I wanted to take advantage of the temperature capability of the new sensor.

Now, I became confused as the port labeled temperature on the side of the sensor was clearly 4 pins and the only temperature probe I had available was clearly a three wire connector… and actually only used two of them! I chatted with a supposed expert on the Horizon web site and they had not physically seen the sensor and could not help, nor did the documentation that came with the unit so much as mention the temperature port.

I had nearly given up hope of finding an answer when I finally noticed the top label of the sensor was (at least apparently) applied upside down… Where the label says X-Bus 1 and X-Bus 2 there is but one port and it is 3 pins…. X-Bus is a 4 pin connection. On the opposite side is a label Temp and on that side are dual 4 pin ports… Clearly these are the two X-Bus ports and the one 3 pin is the temp sensor!! I had already plugged in the single X-Bus port into one of the two ports on the side labeled temp it could only fit on that side. I went to look at pictures and realized that all must be this way! Someone should tell the folks on the assembly line… 🙂

Here is a picture showing the labeling and the correct wiring.

2015-09-09 21.04.58

Turning in the radio after this revelation shows the following…

2015-09-09 21.06.20 I now look forward to actually flying and testing the capacity measurement capability and am excited that I will no longer endanger my batteries by over discharging them. The closest I could do before was to set a low voltage limit which often meant I would get a warning that would sound at anywhere from 5-35% of capacity remaining depending on throttle setting at the time. I have great hopes that with this new capability I can set the alarm for a calculated 80% of battery capacity used and expect a much more accurate accounting.

I will post more as I get time to fly and test this capability.

September 5, 2015September 27, 2015

T28 Carbon Z… Not mine but I got to fly it!

A couple weeks ago I got a call from my flying buddy, Kelly. It went something like this.

“If I were to buy this T28 Carbon Z… could you store it for me? Oh, and would you have a battery or two for me to try? Oh, and could you program my DX-8 to work with this thing?… Not that I’m necessarily going to buy it!” Right….

Of course I said, “Yes, yes, yes… and bring it over tonight and we’ll get it setup”. As you can guess, he did and we did! Here’s what we’ve learned after approximately a dozen flights.

First of all, we took the airplane out with a completely stock setup and tried a few flights with a couple 6S 4000mah battery and while the plane flew nice… it ate batteries at a prodigious rate! We were lucky to get a 6 minute flight and the batteries were down to dangerously low levels to even get that much. Horizon recommends 3500-5000mah batteries and claims 8 minutes flight times for a 5000. We have since found that the 8 minute flight time on a 5000mah is a reasonable estimate however I can’t imagine anyone being happy with a 3500 pack in the airplane so don’t waste time or money on the smaller packs… just go straight to the 5000s… or maybe slightly larger! Kelly got a few flights today with some new 6S 5300 Glaciers and was much happier with the 7-8 minute flights with 30% or so left on the packs!

The plane flies extremely smoothly with great stability and recent forays into the flaps down/low speed arena kept Kelly smiling all afternoon… Also, flying at slower speeds helps extend the flight times! Win/Win!

So here’s a few quick tweaks we’ve applied to this point.

First, since we always try to set up a throttle safety/kill switch, that became the first order of business. In order to get things to work correctly, the throttle cut had to be set to a value of 30… a bit odd but it works great! If you leave the default value and power up the airplane with the throttle cut enabled you get a surprise when you turn it off. The prop starts to turn slowly… sort of a nice low idle! Since plugging in the battery with the throttle kill set to off/run mode sort of misses the whole point, I recommend you set the kill to 30! Of course this may vary with other models or types of radios.

Next, we needed to reverse the gear channel to get the switch working the directly we wanted on this bird. That may sound like just a personal choice but I mention it because it may seem a bit confusing if you’ve not been lucky enough to mess with electric retracts before. Since electric retracts tend to just stop when meeting a heavy resistance, you may not realize which position the switch is in until you take the load off the gear and flip the switch back and forth a couple times. Not a big deal but take the time to play with the gear a bit… and who could resist that anyway… to see how this works and make sure all is happening the way you expect.

Third, in order to maximize flight time without endangering the batteries, we installed a telemetry module and attached the voltage sensing lead to the speed control connection. You can do this a couple ways. There are harnesses available from Horizon you can insert in line between the battery and speed control or you can simply strip back a little insulation on the speed control wires and tack solder them in… just be sure to protect the exposed wiring when you are done so no unexpected sparking and smoke is likely to happen! The telemetry module runs fine off of the included receiver, which is great. We set the warning tone to kick in at 20.5V… Under load this seems to equate to about 30% battery left when it starts to beep. This gives you very reasonable amount of flight time left over to make that perfect approach.

So, up to now, the T28 Carbon Z seems to be a hit…. as long as you stay with a large pack! My limited flight testing indicates it flies… well, like a T28! I prefer the Carbon-Z Cub but the T28 is the best AS3X equipped plane I’ve flown. I’d love to try it without to compare. It doesn’t have the power to weight ratio that the Cub does, but it can climb quickly on the wing and do nice scale maneuvers. It also looks beautiful in the air.

It certainly seems Horizon may have another great aircraft in the lineup. It may seem a bit pricey… but you get retracts, a nicely detailed cockpit and a great looking and flying aircraft for the price with no real deficiencies that I’ve found… right out of the box. That is what an ARF should be.

June 18, 2015June 18, 2015

What does Geotex runway have to do with a float fly??

So normally a Geo textile runway has little to do with a trip to attend the twice-annual float fly at Lake Lemon, just North of Bloomington, IN. But in this case, the outing was dual purpose. Let me explain.

There has been an ongoing discussion at my “home” RC club about the possibility of putting down a Geotex runway at our field. As usual with any group of humans, opinions vary widely on the topic from complacent acceptance of whatever is under the wheels… to those who think laying down some fabric on a small portion of the runway is going to destroy civilization as we know it… to those who think it would be a great addition to the field and are anxiously awaiting the installation! I will admit to being a proponent of giving it a try but I’m not predicting it will be the ultimate solution for everyone that some seem to be hoping for.

“So how does this relate to a float fly?” you are probably asking yourself at this point. The answer is that the folks that are running the float fly are members of the Monroe County RC Club and they have had a Geotex runway for 2 years now. Since I was definitely planning on attending the float fly anyway and wanted to get a first person look at the surface I sent out an email to the MCRCC officers and explained that I intended to come down to the float fly and wondered if they would mind if I and a few buddies stopped by the MCRCC club field and did a little examination and flying from their runway. I quickly got a couple of very welcoming emails giving permission for our visit so I gathered up some interested fellow RCers and planned our trip.

Surprisingly 2 of the party of 5 didn’t even plan on flying at the float fly! They just wanted to see the runway and I guess figured watching us crazy people flying RC planes off of water was just a bonus!

Here’s the visitors…. from L to R. Martin Hooks, George Horning, Corey Lucas, Steve Woods and I was behind the camera.

So here is a quick rundown of the runway…

The installed fabric sits at a level just slightly below the grass which resulted in a very smooth roll from the grass to and from the material. The Geotex runway at MCRCC is about 29′ x 150′ which was very adequate for small electrics and glow up to 40-60 size based on our trial flights. We flew the micro T28 from ParkZone, it’s bigger (42″) brother, the FlyZone Beaver of a similar size, a glow powered Revolver and finally did taxi only tests with my 50cc powered Wildhare Slick. It was not ready for flight that day but taxi tests from just rolling to tail off the ground running on the mains was sufficient for what we had in mind. The observations of the group were mostly positive. The runway seemed to be a bit bumpy for the smaller aircraft (we were later told it had not been rolled yet this year but can be, and probably will be soon). My feeling is that I could wish for something a bit longer and maybe a bit wider to allow for “cheating” into the wind when it is inevitably not aligned with the runway… but it was adequate as is. Otherwise, other than getting used to taxiing on a “smooth” surface, it was especially nice for the smaller aircraft. Aircraft like the micro T28s that just can’t take off from our grass runway at all, and the larger T28 that with stock gear is more likely to flip over than roll out on landing at our field, were certainly in their element on this surface.

The most informative part of the visit though was when we moved onto the float fly site and met and discussed the runway material with several MCRCC members. I have been a bit skeptical that we might need to do some grading to lay down our own Geo textile runway but they did little or no such work at MCRCC. With only roundup and “scalp” level mowing they have had no issues with laying the material down over what they had and have had no issue with it coming up, erosion, wind or whatever. Apparently even when overrun with flood waters a couple feet deep the material stayed put with just the standard staples holding it in place! They also related that they had been through a very contentious process and that the vote to lay down the material had passed by a mere two votes! One gentleman was kind enough to relate that he had been a very vocal opponent of the project but was now a convert and was very happy that he had stood up at a later meeting to say that he was wrong and that he now enjoys the Geotext runway as much as anyone. We have some very strongly opposed folks at our club as well but after visiting with these folks and bringing up all of the objections I had heard from our own members, I was left with the feeling that none of those concerns are really valid based on the experience of these folks.

According to the folks present, the runway is now a big hit with almost every member with some of the (previously) most adamantly opposed now enjoying the benefits. The visit helped allay my own fears that we might be wasting money on something that would need a lot of maintenance or might not work well over our (perhaps rougher) surface. It is certainly not a done deal that we will move forward with the project, but I feel pretty good that the cost to do it this way is low and even a failure will just result in a need to roll it all up and reseed… If we are successful, it seems like we might even attract more of the small electrics/park flyer crowd and open up some new options for our members including more retractable gear aircraft. There was a lot more conversation about things like how to repair damage, rolling, re-inserting staples that push up… etc… but the general tone was that they had found that most of these issues are easily handled.

Moving on to the float fly, it was fairly breezy with some swirling air making the flying a little more “bouncy” but really not bad. I suspect the wind direction (quartering from behind us as we stood looking out at the lake) worked to our advantage since the large hill behind us did much to block the wind. I flew the Carbon Cub through 4 batteries with nothing untoward occurring and did some prop hanging and aerobatics to the applause of some nearby “party barge” occupants that were hanging about a hundred yards or so off shore. Landing with the wind gusting and waves to play with was really fun. With the reliability of the electric power plant and the nimbleness of my AS3Xless Carbon Cub allowing for some sweet splash and goes, spot landings and long wave-top hopping skims it was hard to wipe the grin off my face during and after each flight. I also flew the Flyzone Tidewater which handled the waves and taxi duties great but was a handful in the air with a continuing tendency to dive as throttle is applied. I later figured out the engine pod was leaning forward with increased throttle and did some repairs to help reinforce it. I have since flown it a bit more off grass and it greatly improved and so I am looking forward to a future float fly to give it some more air time.

Corey flew his Beaver on at least 2 occasions and Steve was able to get a good flight in on his cub after some early issues were resolved. Martin flew his Quad a bit and captured this image showing my Carbon Cub on a landing approach.

The Carbon Cub on a nice smooth approach for landing at Lake Lemon…

I’m pretty sure everyone enjoyed the day immensely and I for one am looking forward to (fingers crossed) a successful Geo Textile runway install AND another visit to the fall edition of the MCRCC float fly event at Lake Lemon. Thanks so much to the officers and members of Monroe County RC Club who allowed us to visit their field and participate in their event.