Balsa USA Bristol M-1 Part 2: Straighten up and fly right??

After arranging a battery compartment, getting servos installed, repairing the landing gear mounting holes, radio setup, etc… etc… I took the Bristol out for a couple flights.  It was… underwhelming.  I have a Great Planes DR1 Tri-Plane so not totally unaccustomed to draggy aircraft that need coordination to turn but for some reason I could not get the Bristol to make a smooth turn no matter what I did, nor even fly straight and level without constant inputs.  After 3 or 4 flights I was getting a bit better at herding it around, but if that was as good as it gets… this thing would never find a lasting place in my fleet.

I am not accustomed to just giving up on an airplane after a couple flights… especially if I can’t identify why or what exactly isn’t working the way it should so I started checking, rechecking and gathering info about the plane.  Certainly there are aircraft that I simply don’t enjoy flying, but that doesn’t mean they aren’t doing what they are designed to do, and doing it well and consistently.  I’m fairly sure I started out tail heavy which just amplified all/any other problems.  Later flights I shifted the battery forward and things improved but still not stable/reliable the way any simple aircraft like this one should be!

Eventually I started going through the way it was built and started looking at things that I would pay attention to if I had built it.  Eventually, I found at least one issue that could account for some of the odd flying I experienced.  During any build from scratch, kit or even ARF you should always check the  Horizontal alignment of the wing to the thrust line of the aircraft as well as the tail to the wing and the alignment of the vertical fin at a true 90 degrees to the horizontal.  Since the Bristol looks kind of like a cigar with attached flying surfaces there is no really obvious way to check out the wing alignment to the thrust line but nothing jumps out on that score and frankly, if that’s off a little it probably won’t make nearly as much difference as the tail alignment to the wing.  That is where I found an issue.

If you sit the plane up on a table top and prop up the tale a bit you can visually line up the horizontal tail surface with bottom edge of the wing.  This will show that the two surfaces are at least level with each other.  Well, you can if both surfaces are in alignment.  The Bristol, not so much.  Just to add insult to injury the vertical wasn’t vertical to the wing nor the horizontal stabilizer!

A bit more scientific method was in order, so I set the plane up on a stand and (using a piece of aluminum channel across the wing saddle as a flat rigid platform) set a level across the wing saddle.  I then adjusted the plane to level.  

Once the baseline was established, I measured the tail feathers to see how close to level  they were.  As you can see… not so much.

Left stabilizer

Right stabilizer

Verical fin… not so vertical.

So what to do…  If the vertical had been perpendicular to the horizontal and the body structure had been something more traditional… like my Telemaster for instance… then I might have tried to do some twisting and heating to straighten things up.  But with this cigar shaped body I couldn’t figure out how to make that work or if it was even possible!

So I went with plan B and created some wedges out of small pieces of popsicle stick and did a little cutting, wedging and regluing.  Here is how it looks.

3 wedges, literally hammered into place on the starboard side of the vertical fin.

Then added a couple more on the top starboard side of the horizontal stab.  I also put a couple on the port side bottom of the horizontal stab as well.  The result was this.

Left stab now…

Right stab now…

Vertical now…

I’m pretty happy with the improvement and I’m debating adding some flying wires to help get the last couple degrees of adjustment I need to get to “perfect”.    I think it may be the only way to maintain the proper alignment between the surfaces under flight loads in any case.

I’m hoping to get a test flight in again soon and hoping that now that I have the tail all straightened up, the Bristol will start to fly right!

Balsa USA 1/4 Scale Cub – Part 5 Finally back on the bench!

The cub has been sitting quietly in the corner of my shop for two and a half years now while other projects came and went including dozens of repairs/builds and modifications to my planes as well as many visitors projects.  It even survived the move that is nearly 2 years in the past now with no damage… so finally it has found its way back to center stage on my bench. 

If you want to catch up on the old posts, here are links to each:

Balsa USA 1/4 Scale Cub – Part 4 More Mods – Rudder Shape.
Balsa USA 1/4 Scale Cub – Part 3 More Mods – Flaps!!
Balsa USA 1/4 Scale Cub – Part 2 Modifications begin
Balsa USA 1/4 Scale Cub – Part 1 Acquisition and plans

Mostly getting back to this project came about because my flying buddy, Garry Bow, bought a Dave Partrick 1/4 scale Super Cub at the swap meet in Toledo this last spring and though he sold it before getting it in the air again, we have been talking about it enough that other folks in the club have decided to enter or re-enter the brotherhood of RC cub fliers.  I think almost every RC airplane enthusiast has already, or plans on getting, one variation or the other of the J-3, clipped wing, PA-18 super or maybe even one of the more modern variants like the Carbon Cub.  Cubs lend themselves to slow majestic flying and there are many different variations that allow for you to fly a cub that is at least semi-aerobatic, can tow gliders, carry a drop box, sky diver, camera or whatever.  Most Cubs are almost instantly recognizable to even those who don’t pay much attention to aircraft or RC and also make great entry points for scale building.  Cubs can be very simple 4 (or even 3) channel setups with a high wing and light wing loading.  This allows for slow and gentle landings and the typical Cub landing gear configuration can absorb some punishment in case of abrupt landings,  especially those outfitted with bush tires and working shock absorbers.   So it is time to get back to my latest endeavour into the the world of Cubs. 

My latest cub started life as a Balsa USA 1/4 scale J-3 Cub kit but I have been working to make it into something closer to a Super Cub.  I’ve detailed a lot of my modifications up to this point so I’ll try to just continue where I left off a couple years ago!

Looking back I realize that I did make one more significant change that never got posted and that has to do with the wing attachment method.  I really disliked the way the wing attached.  It seemed like it would take 3 people to get the wings on and off without damage to the airplane with just a location pin and bolts holding on those massive long wings.  I didn’t like the thought that damage to the root rib seemed likely if you didn’t get the struts on quickly before a gust of wind or careless bump to the wing caused an issue.  This design was made for someone who is much better organized and meticulous than I!

So right before I packed it away, I added a small wing tube arrangement to my Cub.  At first, I tried to put a straight wing tube and sleeve in place but then realized that a straight tube was not going to work well in a wing with dihedral!  So I assembled and shimmed and adjusted until the wings were sitting at the proper angles and then created a wing tube for each side utilizing the servo wire guide holes as a ready-made mounting point for the sleeves.  The tube itself is a carbon fiber tube from a friends wrecked airplane and the sleeve is an aluminum tube that the CF rod fits perfectly inside of.  I butted the tubes up in the center of the body and created a couple of new rib structures (complete with cutouts to make installing the mounting bolts easier) to hold them in place.  Now all I have to do is slide the tube into the wing and slide the whole assembly into the body and the wings have enough support for me to take my time bolting them in and attaching the struts.  Time will tell if this system works the way I hope it will.

Since I retrieved the Cub from its dark corner, I have started working on a couple of other changes too, including a new tail gear, engine mounting, and a glider tow release.  I’m still debating lighting options, float mounting (I have no appropriate floats yet), a possible belly pod (to mimic a baggage pod or fuel pod, both of which are in use on many Super Cubs) for candy drop or whatever, and possibly some hard points to carry a very non-scale sky diver drop mechanism I have.

Also, I have started to plod forward with the final steps the previous builder never completed like window installation, wing leading edge shaping, etc…  I’ll try to post on some of these activities soon.

Balsa USA Bristol M-1 Part 1: Motor mounting

A while back, my flying buddy Gary gave me a Balsa USA M-1 Bristol as a thank you for some work I had done on an airplane of his… or maybe it was a few airplanes… or a bunch!  Anyway, we had both seen it at a swap meet and I had admired it but he bought it.  I think it may have been traded off and then reacquired at some point before it found its way to me but in any case it has been sitting in a corner of the shop for a while now and I finally picked up what I think will be an appropriate power system for it, the E Flite Power 46 and a Castle Creations Talon 90 Speed Controller.  The Talon is a bit of overkill but for some reason seems to always be available at a relatively lower price point in the Castle line (my favorites).  It has an outstanding BEC capability and can handle up to 6S and 90A.  Castle and E Flite are among my favorite brands.  

The first task was to build up a good engine mount for an airplane that was kit built to mount a glow engine.  To mount the motor out far enough to get the back plate beyond the cowl face means spacing out somewhere around 3″ to the back of the motor in this case.  Nose weight is also not a consideration since the Bristol is so short nosed and more likely would need more weight up front if anything.  Finding some 3″ spacers is difficult at best, and I like the idea of something more rigid anyway (long spacers tend to flex or twist a bit under load).

To accomplish this I decided on using some shorter spacers mounting to what I refer to as a sub-firewall and then more short spacers to the X mount on the back of the motor.  This assembly is very strong and uses a few easier to find smaller spacers and some rigid plywood to put the motor out where it is needed.  Here are some pics showing the assembly.

 

Motor attached to sub firewall

Sub firewall bolted to firewall

Mounting plate tie wrapped to spacers used to mount speed controller.

With the cowl in place

There are a few other necessary installation tasks… servos to be mounted, an arming switch to mount, and making sure the battery can be located in a spot where the plane will balance… but progress is being made.  Looking forward to flying.

P-47 Bonnie reassembly and lessons learned.

My local hobby shop, Hobby RC, got my replacement body and decal set in quickly and so the process of making this craft flight worthy again could begin!

Immediately upon unpacking a couple of things became obvious.  As you can see here:

The decal set I ordered would not be necessary.  Unfortunately the picture on the web site showed the spare part without the graphics.  I’m happy this is the case but could have saved $15 if I’d known.

Next I noticed the rudder was not attached and I had no idea to this point how it was attached… the original came on my plane… I’m pretty sure…

Turns out the rudder just clips onto the body by the use of built in plastic clips and pins built into the two parts.  You simply push it on and it pops in place…  Couldn’t be much simpler.

After screwing on the two halves the elevator with the 4 black screws.

I pushed the rudder on and started flexing it back and forth when I noticed that it didn’t allow for much throw (I had been thinking it needed a bit more) plus I noticed that it tended to flex the elevator joiner, resulting in some deflection…  that had to change.  So taking advantage of that easy removal, I popped it back off and opened up the pass through slot with a sanding drum on my electric rotary tool.  You can see how tight it is here in the before photo:

Quite a bit of material needs to be removed to get a significant amount of throw AND keep the pressure off the elevator joiner.  Here’s the old and new with the modification.

And here is what it looks like installed.

 This allows for the maximum throw allowed by the factory servo and linkage setup without binding.  Sliding the push rods back in place and installing the servos on the rails was pretty straight forward.  I notice the servos have no rubber grommets on the tabs… though I suppose in a foam body electric, vibration problems are fairly limited so no need.

While I was working on the tail, I flipped the plane over and went to work reinstalling the retractable tail gear.  Only something was missing!

The plastic insert that everything mounts into was not in the new body… time for some surgery on the old body again…  You can see here that it takes a lot of carving to get this thing out.

And here is the piece that comes out.  It takes a little cleanup from here.  You need to get all the foam off of it to easily insert it into the new body.

After getting the plastic insert into the new body, mounting the servo followed by the retract itself was pretty straight forward.

Mounting the servo and retract outside the aircraft is more straight forward than it was taking it out while still inside the tail of the plane.  Route the wires (easier if you have “grabber” like the one you see here) and with a little glue on the contact points with the foam just slide the assembly back in place and we are back in business.  

Reattach the doors and springs (a little bending/adjustment is likely needed) and everything goes back together fairly easily.

Next I reinstalled servos and the control board with it’s associated plywood tray inside the fuselage as well as the connector boards in the wing root.  You’ll want to check your notes or photos on which wires plug into what as the labeling is helpful but not completely obvious.  Once again I ran into a small issue where my notes and pictures were insufficient.

Here is the starboard wing root 

Note the one socket is closest to the trailing edge of the wing.  As you reinstall the matching plate in the body, be conscious of this and note that the port side is opposite…  I just “assumed” that both would be installed similarly and it turns out not to be so.

Most everything else went back in with no issues, though I encourage you to take copious notes and photos if you have to do this for yourself.  It will help immensely to guide you in the rebuild, knowing which screws to use, etc…

As I was assembling for final adjustment of the servo linkages and testing I found one more casualty.  Here are two of the wing screws…

As you can see there was a bit of force exerted when one of the wing tips found the ground.  These bolts are a little bit soft (which worked in my favor in this case!) so I was able to simply use some padding around the bolt in order not to mar the threads and bend it back into shape with pliers.

I made a final “rebuild” step by peeling the custom graphic for my crew chief (my Grandfather) and successfully reapplied it to the the new fuselage.  Welcome home Grandpa! 

While the P-47 was in the shop, a few additions were also made.  With the addition of a telemetry module and associated sensors (GPS, G Force and Voltage sense wire…) I’ll be able to keep a better eye on my battery pack voltage, ground speed and other interesting tidbits.

This last weekend we had a nice event at the club field during which I got in 6 or 7 flights.  After a bit of elevator trim during the first flight, the Bonnie proved she was back in peak form.  Her pilot took another flight or two to get back in the groove…  I did make sure that the battery was securely attached to the battery tray before each flight and I may add additional measures to be sure the whole assemble does not leave the plane prematurely.  For now just being sure the straps on the tray also engage the hook and loop material on the battery seems to be working.

P-47 Bonnie – battle damage

The FMS 1500mm P-47 continues to be my favorite flying War bird that I’ve ever flown.  Because this is true, it has gotten quite a few flights in the past few months.  But now there’s going to have to be some repairs before any more flights occur.

The P-47 flies so well that I tend to push it a bit from time to time and such was the case the other day as I lazily cruised around inverted and enjoyed the inherent stability of the air frame.  When I needed to get back upright I pushed a bit of extra power and pushed a moderately tight outside 1/2 loop…  Unfortunately at that point the battery decided to exit the airplane, in the process pushing off the canopy and of course disconnecting itself from the rest of the aircraft in the process!  Yikes!

After that there was much confusion.  The airplane rolled to upright (which I was trying to do) and stalled nose down at about 250 feet.  At first I thought I had occasional and/or partial control so I continued to do what I tell everyone else to do… “Keep flying the biggest piece!”  The airplane porpoised quite a bit and every time the nose came up I jammed in some down and it righted itself (yes, I know I was merely spectating at the time but I kept trying!).  This continued and the airplane also turned back toward the runway as I intended and actually ended up landing only 10 feet or so off the mowed part of our runway near “show center”.  Unfortunately the last porpoise up and stall was from about 10 feet and it hit moderately hard on the lower part of the cowl.

I can’t be absolutely certain, but my best guess is the battery slipped from the hook and loop straps, leaving the tray in the plane while the battery pushed the hatch off and bailed out!  The tray was laying next to it in the grass. I believe ejected on impact.

 What follows is a photo catalog of the damage incurred and the various disassembly I have done since in preparation for the replacement of the main body.  The impact (I maintain the rule that you can’t call it a landing if you should say impact…) made a couple cracks in the cowl and compressed some foam on the bottom of the nose, as well as splitting and cracking the first 12″ of so along the bottom seam of where the two foam “halves” come together.  The motor box is also a bit more loose now than it used to be.

It is certainly something that could be repaired with just some glue but it would be a bit ugly and I don’t want to go to the effort of a full repaint of the body, which is what it would take to make it look good again.  A new body is available and at ~$85 not out of reason.  As my buddy Kelly says:  “Let me know when this hobby gets cheap.”  I will do quite a bit to avoid painting as I have no talent for it, nor proper equipment or appropriate paint area to do it right.  Disassembly and re-installation is in my wheelhouse however!  So to start, here are some pics of the damage.

Here are the cracks in the plastic cowl piece.  Looks fairly fixable since there isn’t any compression… glue, clamp and go I’m hoping.

This shows the side of the cowl.  As you can tell, as the cowl pushed back at the bottom, the top pulled down and forward which ripped some of the mounting points loose.

This is the bottom of the nose where you can see the split seam and cracks and compression radiating out from the impact zone.

You can really see the compression and re-expansion here.

As you see here, lots of compression further back as well.

Back edge of the canopy… more compression?  Or maybe from impact when it touched down.

Time to start disassembly.

Remove this cover to get to the tail wheel steering servo…

Steering servo to the right, retract left… screws holding retracts already removed.

Remove the springs from the landing gear doors before removing the doors.

If you flex the doors, the pins can be popped out of the loops without damage to either.

Removal of the Horizontal stabs is a simple matter of removing 4 screws.

 Remove these two screws in the rudder to remove the rudder horn.  Pictures on line seem to indicate this part may come with the new body but just in case…

Here’s the distribution board that drives all the in-wing electronics.  The two white connectors feed the wing root connectors.   Port side connector feeds to Starboard wing and visa-versa.  4 screws hold it to the mounting plate.

Here are the servo wire connections to the mixer board for reference.

The distribution board screws through these three layers of plywood.  Notch out portions to the rear.  The lowest one is glued but can be pried up with some effort.

This is the magnet that holds the rear of the canopy on (except when a 2lb battery slides out with the help of a couple/few G’s of force and pushes it off!).

While you are there remove the servos and the linkages by unscrewing the clevises at the elevator and rudder and pulling them out from the servo end.

This is the wing root connector.  Held in with 4 small screws.  Wires fish through without to much effort… re-fishing them through looks easy enough.

Aside from that, removal of the motor and speed controller is pretty straight forward.  The speed controller is very easy to remove if you fail to properly secure the battery and do some negative G maneuvers!!!  (To soon?)

Reassembly to come… I hope!

P-47 Bonnie gets some flights

Last weekend I managed to get out and put some flights on the 1500mm FMS P-47 Bonnie…  The short version is “very nice”!  Here “we” are after a couple of flights.

I’ve always had a soft spot in my heart for the mighty Jug for a couple of reasons.  The P-47 is a workman like craft.  She’s big and heavy, not the sexiest but she is powerful, deadly and protects her pilot.  P-47s were built in two places and one of them was the plant in Evansville, IN where my grandfather (mother’s side of the family) helped to build them!  There are family photos from the plant (which later became a Whirlpool plant that created lots of consumer appliances) showing gun testing going on in the middle of the night using tracers!   This was a 24×7 operation so darkness could not halt the process.  I can’t imagine living nearby and listening to those 8 .50 caliber machine guns going off at 2AM!  Just another hardship of war I suppose.  Most of those families probably had folks working in the plant and so understood well what was at stake.   In honor of grandpa, I added one customer graphic, making him the crew chief on my P-47.  His name was Jesse A. Lane.

With Grandpa taking care of the mechanicals, I got in a total of 5 flights that day and the plane performed well.  She has a wide flight envelope from nice and slow to fairly impressive high speed passes.  She kept up with an EDF that happened to be in the air during one of the flights and at the same time slowed down nicely with medium flap settings.  Gentle/slow landings combined with the ability to fly the plane fast enough to be convincing (a fighter should not spend a lot of time just floating along should it?).  This is a somewhat rare and welcome for a war bird and gives me hope that I will fly this more than “once in a while” as it makes the plane actually enjoyable to fly versus flying like a kite or white knuckle landings being the norm.

I still have some tuning to do… need to adjust the elevator to flap mixing and adjust my throws and expo settings to my liking.  Also need to double check that motor box “flexibility” that I noted in my first post on this airplane.  I may have imagined it, or it may just be a result of the down thrust built into the airplane, but it seemed as if the plane would push downward with application of full throttle.  Not a drastic issue and perhaps if I can firm up that motor box this would go away??  We shall see.

Overall, I am very happy with the flight characteristics and overall performance of this airplane.  It is the first war bird I’ve bought that I am looking forward to flying frequently in the near future.

From a non-flying perspective I did my usual cut outs from a styrofoam cooler and created a cradle and I purchased some wing bags to protect the soft foam, guns, etc…  That works well as long as you actually tie the cradle down in the trailer! 

The soft foam continues to be a concern so continued care is necessary but so far I’ve managed to keep bumps and bruises to a minimum.  Also, the wing connectors are holding up so far but I only have a dozen connects and disconnects on them so far so will have to watch those as well.  It’s also worth mentioning that the retracts have performed flawlessly up to now.  I attribute part of that to the fact that she lands pretty easily so they aren’t getting the abuse that a heavier bird would put on them.

Overall I am very happy with this aircraft.  FMS seems to have done a great job and I recommend you get one for yourself if you are so inclined.

FMS P-47 1500mm “Bonnie” added to the hangar

FMS 1500mm P-47 Razorback Bonnie PNP

After months of serious consideration, comparison and reading hundreds of comparison posts I finally pulled the trigger and picked up the 1500mm P47 from FMS.  As usual, my local hobby shop got me a great deal and in a few short days I had a rather large box full of airplane in my shop.

Bad : 

  • The foam is soft… dings and dents are already building up.
  • Some sloppy glue… the wing tip lenses are both a bit “slimed” with glue.  
  • Inner gear door linkage maladjusted… both were drooping  a bit, 2 turns on each clevis solved the issue
  • Wobbly motor mount.  Entire structure appears to be moving in the foam.
  • Finish is not as smooth as other foamy aircraft
  • Decals are thin, some lifted a bit, piece missing out of one
  • Bomb attachment.   Brackets pull out before release occurs

Good:

  • Overall finish is very pleasing with the exceptions noted above.  Lots of scale details, especially in the cockpit.  Ordinance, lights, 4 blade prop, panel lines etc…
  • Light weight and light wing loading along with flaps should make the airplane a kitten to land
  • Build is nearly complete out of the box.  Rare for a complex war bird like this.
  • Wing connection plate makes wing assembly simple… no chance of missed connections.

Questions

  • Wing connection plate… to loosen or not??
  • Carry method…  Wheels in the wings so what to do?

Let me expand a bit on the above in reverse order… First the questions.

There is a nifty connection plate and mating plug where the wing root meets the body.  Since the wing inserts into pockets and has two aligning rods, the connectors meet up perfectly and seat together snugly… or at least it appears so and they work nicely right now.  There are a few reports of issues with this connection.  Folks have had a few intermittent connections and the like.  Some people have avoided or resolved this issue by loosening the mounting screws on the plate mounting in the body.  I think the idea is that if the mount is not rigid, vibration and the like won’t cause an issue.  Should I pre-loosen these or wait for an issue (and hope I don’t crash when/if it happens)?

Carrying this plane is going to require some thought.  I can’t leave it assembled… there simply isn’t enough room in the trailer… but like a number of other planes the main gear is in the wings so once you take those off that round body there will have to be some sort of carrier created to keep the plane from becoming a hangar casualty!

Now for the good stuff…

The color scheme chosen for the bird has enough color and lots of striping so that it should be very visible in the sky and orientation shouldn’t be to hard to track.  The cockpit has some nice touches and the wingtip lights are nice and bright.  While not every panel line is captured, a vast majority are there and while they may be a bit more pronounced than needed it adds to overall look of the airplane.  From a few steps away, the plane shows nicely.

The weight of the aircraft is on the lighter end versus what i would expect from a warbird of this size so I’m expecting some good flying and landing characteristics, especially with flaps being available.  I doubt she will float, but I don’t expect to have to make super shallow landings at high speed that require huge amounts of runway either.  With the flaps deployed I would think a more ordinary approach will be possible, holding just a little extra throttle in to keep the wing flying.

The completeness of the build out of the box is impressive.  Attach elevator linkages once it is in place and assemble and mount the prop and you are about done!  Even the decals are applied in advance.  There isn’t much of the “Almost” in the “Almost Ready to Fly” P47!

The electronics in the P47 are by necessity a bit complicated but as opposed to other similar aircraft I’ve dealt with, FMS has done a great job of eliminating that issue.  Everything is pre-wired and connected and attaching the wings requires no messing with wires at all as the wings have a built in connector at the wing root that takes care of all that for you.

And then the bad…

This airplane is built out of some of the softest foam I’ve seen.  I’ve already accumulated a number of dings and dents… some wrinkles and thumbprints in the stab just from trying to get enough force on it to assemble it.   As well, the body has several dents just from resting it on my airplane stand which is made of harder foam.  This may actually bode well for it’s survival but I’m half expecting it to get “ugly” quick.  I’ve seen somewhere a suggestion that using a warm, wet rag may help relieve some of these but I’m worried about what that will do to the paint as well…

Speaking of the paint, it seems to have the same issue that I have seen on planes like the Carbon Z Cub.  It doesn’t take much to peel or flake it off.  Also there is some over-spray in some areas that occurred when the paint was applied.  I could wish for a bit better application. 

I have been adding some additional graphics and replacing some of the decals with vinyl and there is simply no way to get them off without peeling the paint underneath.  That might be to much to ask but in some spots it amazed me just how easy it came off.  I don’t want to do a full repaint so I’m only applying graphics that are the same or slightly larger than the original and doing everything I can to not lift the paint around any decal I remove… sometimes slicing it with a razor blade at the seams to maintain the surrounding paint.  Luckily the vinyl is a bit thicker and covers the patchy mix of paint and bare foam that is left behind.

I have found only two areas where the assembly/build of the plane could reasonably have been improved.  First is the wingtip light lenses.  There is a lot of sloppy glue work inside both lenses.  Unless I pull them off (which risks damaging the surrounding paint and foam) there isn’t much to do about the strings and globs of glue on the inside of the lenses.   Second is the engine mount.  It is obvious that the entire engine mount if flexing slightly as the motor runs up.  I’m not sure if it’s just a function of the soft foam or if some extra glue would solidify this…  I may eventually try injecting a small amount of expanding glue like Gorilla glue in a couple spots around the mount to see if it helps.  I don’t think the motor is going anywhere and balancing the prop might help minimize this issue as well but it’s something worth looking into.

Another minor issue was on the bombs.  The attachment method of the “brackets” into the top of the bombs was apparently a couple pins and spit (errr… I mean glue of course).  The second time I tried to detach them from the pylons on the plane, the bombs parted ways with the brackets.  A good application of Foam Tac and this problem seems to be resolved.  I also recommend you always attach and detach the bombs by grasping the plastic brackets versus the foam of the bombs themselves.  

I promise to follow up with some more info after a flight or two.

When is an ESC a BEC?

I was recently reading in some forums and realized that many folks misuse the often used acronyms ESC and BEC when discussing the power systems in their electric aircraft.  It seemed evident that some of the folks were using these terms interchangeably and likely could not have actually defined either.  So my purpose here is to define each and plant some basic ideas about what they do.

An ESC is an Electronic Speed Controller.  This device is what takes power from the main  battery and feeds power to the motor.  The amount of power that is passed is normally determined by input provided by the receivers throttle channel output.  ESCs are normally rated by the voltage range they can accept and the amperage they can pass without damage.  More on these rating later.  Obviously, any electrically powered airplane is normally going to need this device to control the motor speed.  An ESC has nothing to do with providing power to the receiver and servos.  That is the next topic.

A BEC on the other hand is a Battery Elimination Circuit.  This device is designed to take the voltage of the main battery and regulate it down to a voltage that is safe for our on board radio gear.  Most output around 5 Volts.  The whole terminology revolves around the fact that, without this device, the aircraft would have to carry two separate batteries.  One to power the receiver and a second to provide power to the motor.  So this circuit quite literally eliminates the need for one of the batteries.  Again there are two important ratings here.  What voltage can the BEC take as an input and how much current can it provide?  A BEC can exist as a standalone device (also known as a Regulator) or be incorporated into the ESC.  If it is built into the ESC, it will normally provide power to the receiver via the throttle “servo wire” connection.  I quote that phrase as there is no servo involved but it is using the same physical plug and wiring as a servo so that it can plug into your receiver.

Having the BEC built into the ESC is probably what causes some of the confusion as folks who do not know what the two acronyms stand for assume from the usage that they are one and the same.  Understandable, but incorrect.

So, one might assume that the simplest and best way to handle powering your on board electronics is to always buy an ESC with a built in BEC.  That is certainly the most common way, but there are some issues to consider.

First, you need to understand a couple of things.  First is that using a BEC at all has both advantages and drawbacks.  The main advantage is the elimination of a second battery pack with the attendant weight and cost that carrying a second battery involves.  The main disadvantage is that you are now putting all your eggs in one basket… i.e. the only power source for both the motor and your flight controls is a single battery.  If anything causes that battery to disconnect or fail, you are suddenly a powerless spectator to whatever occurs next and it likely isn’t going to be pretty!

For a vast majority of electric aircraft, this is a reasonable trade off.  Chances of a problem are small and in many cases it is simply not practical to carry a second battery pack.  This is really no different from most glow powered airplanes as they typically only have one battery for the radio system and a failure there has the same result.  But as planes get larger and more powerful… there are additional considerations.

First, remember that BECs are rated by their input voltage capabilities and amperage they can provide.  Something to keep in mind is that it is a basic truth of electronics that while it is easy to take a voltage in and reduce it by a small amount (think 2S Lipo/8.4V battery pack being regulated down to 5V) the higher the input voltage is the “harder” it is to do so (think 10S/42V pack regulated to 5V).  And when I say harder I mean it is more expensive, larger and or heavier and creates more heat… none of which are good things in an electric airplane!  Another difficulty is that the more current you want to design the BEC to pass the more difficult it is as well with the same design trade offs.

So aircraft that require more and/or stronger servos because they are bigger, faster or whatever need to pull more current to run their servos and may quickly outstrip the ability of a BEC that is built into the speed controller.  Also since aircraft that require more/stronger servos are likely also running 6-12s power systems…   The speed controllers in these planes often do not even include a BEC because the engineers designing these know all about the aforementioned limitations and aren’t going to include a BEC that is unlikely to be of any use in the aircraft for which the high powered ESC is designed!

Finally, one often overlooked rule of physics/electronics is that servo wires/connectors are not designed to carry more that ~5A continuously and therefore providing a much stronger BEC with a single servo wire to deliver the current would be silly.  Note that I said continuously.  Connectors and wires can handle higher current for short periods of time.

There is much more to discuss when it comes to power systems in electric aircraft but those are fodder for another post.  Hopefully this article has helped some folks to better understand these two key components.

 

Spektrum iX12 – 1 month in…

Image result for spektrum ix12

One of my more recent additions to the RC hangar is not a new airplane but instead a new controller.  I have been using a DX18 for a few years and have found it to be an excellent radio.  I have zero complaints operationally with the 18 but I really like the newer designs that have come out without all the excess “chromed” plastic.  What’s the point in putting a coating over plastic that will eventually wrinkle/peal and otherwise just create issues?  It looks nice if you like chrome I suppose… never a big draw for me… and sometimes can create glare issues on especially sunny days.  Also, while not a big fan, there are times when a voice notification would be welcome.   I’ve held off because previously they were rigidly defined.  Want the radio to say “charge my battery!”?  Sorry, the only message available is “low battery”.

Spektrum’s approach of putting an Android tablet functionality “up front” in the iX12 sounded like it would have some nice advantages and I haven’t yet needed channel 13 and up on my DX18… so after a bit of research I took the plunge.  Hey, it’s a hobby!  If I’m going to get a little closer to the “bleeding” edge of technology in some facet of my life, this is the place to do it.  So after some time with the radio here is what I have observed and what I’ve done so far.

So far, I have had zero issues… I am somewhat familiar with Android so I think I have avoided some of the odd issues that folks on some of the forums have reported.  I moved 16 models over from my DX18 Gen 1 and everything has worked great so far.  I’ve flown a couple small quads plus 4 or 5 indoor airplanes and other than messing with the spoken prompts, I haven’t modified my setups at all.  Generally, I like the look and feel of the mechanicals of the transmitter.  If you’ve ever handled a DX9, you will find much of this radio to be very familiar.  Some parts of the box are even better, like the back sliders (which I rarely use) being much smoother.  The UI is not yet totally intuitive to me but I’m getting accustomed to it quickly.  I am beginning to like the text to speech options though I wish the audio defaulted to all OFF.  Will probably build myself a template for future use to accomplish this.

The radio is not capable of terribly loud audio levels and some have complained about that.  It certainly is not capable of the same volume of the DX9… Of course folks complained about distortion with the DX9 so Spektrum may not have been able to win this one!  Volume is not an issue for me as I intended from day one to use a blue tooth headset as I hate hearing the constant chatter of audio from other folks radios while I’m trying to fly.  I like to hear my aircraft (and others) and all that chatter is distracting and irritates me after a while.  I also think it impedes communication with my fellow pilots as needed for safety so I love the blue tooth headset option afforded by the Android interface. 

In order to make the audio usable, not annoy my fellow pilots and maintain safety I intend to use a single earpiece.  I bought the Sentry BT950 so I can use whichever ear I like… So far I like how it sits on my neck and audio seems plenty loud.  I have a couple other Bluetooth sets so I can try some others if need be but this one is a nice cheap option I can afford to leave in my flight case.

I also picked up an inexpensive blue tooth keyboard and mouse (Logitech model K380 and model M535, refurbished).  Both paired up and worked right off.  One oddity that was noted in some of the forums was apparent immediately.  When used in conjunction with the iX12, the enter key doesn’t function as you would expect.  So far the esc key seems to function in place of the enter key for text entry.  I’d bet there is an app that would remap the keys for me but I’m OK with using the esc key for this purpose.  The mouse works great and even has a “gesture” button that can be used to do swipes and such so you can pull up the various “side” menus etc… I’ve only used the mouse and keyboard a bit during setup of new aircraft but so far it seems like a great alternative to using the screen based keyboard to create all the text to speech prompts, timer call outs etc…  Do I need them to accomplish this?  No, but I like to have the option for anything that is going to require much typing.  I don’t even like to send long texts on my touch screen Android phone so having a keyboard is a nice option for me.   All my blue tooth hardware total cost me $70 and I will use some of it for other things so in my mind they are cheap at the price and nice to have options.

I routinely pull pictures directly from the web using the Chrome browser on the radio to use as my icons in the model selection screens and downloading the updates from google play is a nice and familiar way to operate so the ability to connect to a WiFi network directly from the radio is another nice to have option.  All in all, I like the radio so far.  There have been complaints about some issues (minor for me) like the audio level, slower model selection than other radios (30 seconds to change models versus maybe 5-10 on most radios) and the fact that it takes about 2.5 minutes to go from powered down to fully functional the first time you power up at the field.  This last is something you adapt to fairly quickly.  Just turn it on when you get to the flying site.  By the time you get a plane or two out, all is ready to go.  During the day, simply double tap the power button and go into sleep mode after each flight.  Coming back to full power up from there is a couple seconds.  The battery will last all day using this routine. 

As I worked with the radio a bit there were a couple of additions I decided were worthwhile.  First, there is a company (Powerhobby) who sells vinyl wraps for the face of many transmitters including the iX12.  I have occasionally dropped something onto the face of my transmitters in the past and I thought maybe this might give it a bit of extra protection.   Also a little individuality never hurts… I already know of one other guy in the club who has an iX12 on order so now there won’t be any mistaking mine for his!  Installation of the vinyl was a bit tedious but not terribly so and I think the result is pretty nice.  Here is what mine looks like after the application.

In addition I quickly noticed that the touch screen was going to often get greasy and spattered, etc… so I decided to take the leap and try to find a good screen protector.  I have not had great luck with the cheap plastic sheets you get for cell phones… they either mute the sensitivity of the screen, cause visibility issues, etc…  so I looked for a glass cover for this use and actually found one sold through Radiocontronics.  It is made of something marketed as “AirGlass” and is apparently from a company called Brotect.  I hesitated to spend ~$24 with shipping for what looks like a highly hyped piece of plastic cut to shape… but I have been pleasantly surprised.

Installation was pretty straight forward.  Clean with supplied lens cloth and carefully drop into place.  Done.  So far I have to say the screen is every bit as responsive as ever, there are zero bubbles or imperfections and so far it seems to pick up less dirt and finger “grease” than the screen itself did.  I wish it were just a millimeter or so bigger in both dimensions than it is… there is a very fine line around the screen that is visible if you know what to look for but is probably not noticeable to anyone else.  That aside though, I have to say it is working as advertised and if it keeps all those microfine scratches off my screen that my DX18 seemed to accumulate regularly (and it wasn’t even touchscreen) than I will be ecstatic.

At around the $600 mark, I think there is a lot to like in this radio.  And yes, I am a bit of a Spektrum fan for which I make no apologies.  I have worked with several other brands like Futaba, Hitec, Airtronics, Multiplex , Graupner and a couple others I can’t even recall.  All of them have some interesting features and strengths but it is hard to beat the Spektrum value for the dollar, excellent support and good balance of feature set with ease of programming.  The iX12 leans toward the more complex end of their line of radios so it may not be the ultimate answer for those who are not smartphone savvy or that are just happy with their DX7s or 9 or whatever but I think I’m going to enjoy it for quite some time.  At least until the iX12 Gen 2… or iX18 or whatever hits the market next! 

 

X1 Pro DC plus ePowerBox 17A Power Supply

I’m constantly updating and hopefully upgrading my RC gear and recently I decided I needed a new charger. The one I bought is the Hitec X1 Pro.  I bought it in combination with the Powerbox 17A power supply. 

Hitec RCD 61070 X1 Pro DC Multi-Charger E Powerbox 17 Combo

A couple of reasons I think the X1 Pro will serve my purposes.

1. Power
2. Portability

I have been doing some flying indoors as well as running an RC car at the local track and I found that my current charging options (a Hitec X4 CD charger and my PL6) just don’t fit the bill for a couple reasons. The Hitec is adequate for some needs but with only 50W power per channel it can be a bit slow for some needs and requires a DC power supply to run it which adds more weight and bulk… especially since all my 12V supplies are fairly heavy and large. The PL6 certainly has the power but it also needs a DC supply and it is a fairly pricey charger so I don’t like to drag it around very much for fear of damaging it. It usually stays in the airplane trailer or the shop.

After my buddy Corey picked up the combo X1 and power supply I had a brief look at it and decided it might be the solution. Power supply and all it is very small and is capable of charging at 180W! That means I can charge a 2S (for the car) at around 20A if I like! This could be a very quick charge for a single battery or I could charge several of my more common aircraft batteries at once with a parallel board.  Even with the power supply the unit is a <6″ cube so portability is excellent as well. Another bonus is it can discharge at 30W which is better than most chargers so getting down to storage charge when needed is quicker as well. Second bonus is the price for the package.  I have seen them from $130 to as low as $80 for the pair… Hard to beat even at the higher end of the price range.  So I brought one home today.

When you unbox the X1 and the power box you will find that you can connect the two with some nifty little double ended banana plugs.  They supplied 4… 2 are needed.  I suppose they will eventually wear out so having spares is a plus.  I removed the little rubber boot on the bottom of the X1 and plugged the two units together with the double ended bananas and presto, I had a fairly compact and powerful AC powered charger. 

In fact, it is compact enough that I don’t think I’ll be taking it apart anytime soon so I decided to come up with a way to keep them semi permanently attached in this configuration.  I can see where leaving it this way and packing and unpacking it might stress the bananas so here’s what I came up with.

First I loosened some of the cap heads on each side where they are closely adjacent on the two units.  Then I took some wire and bent it around in S curves such that tightening the screws would capture the wire.  Here’s a closeup.

I did this near all 4 corners and now the unit is practically one piece.  Since I used fairly small, semi-soft wire I can easily take this back apart if I decide I want to modify this setup later.  I may eventually make something more like a “latch” from servo arms or something but for now I think this will work well.

My only trepidation at this point is I need to find a proper box or padded bag to put the unit in to protect it when it’s in my car “satchel” where it might get rubbed against and scratched.

I have only run the charger a couple times so far but I am quickly getting accustomed to the controls (just a slight difference from most I have used). 

Finally, the first time I tried to pull the connection that goes to the balance board from the charger, I had real trouble releasing the catch.  There didn’t seem to be enough room between the connector and the case to release it and pull it out.  I almost pulled the connector right off the pins!  A razor knife took care of the pesky latch!   Nothing else I have needs a latch on this connection so I don’t think I’ll need it.

So far, I think the little X1 with the Powerbox 17A is going to be a welcome addition to the charging lineup around here.  I have seen some indications that they may soon do away with this charger and power supply!  I hope not as it seems to fill a niche for me and think others may be interested as well.