Aces High P47 Retract issues and repair

I’ve really just gotten started flying my Aces High P-47, with maybe 6 or 8 flights as I figure out the ideal balance, throws and flight envelope for this airplane.  However all of that got a bit sidetracked a few days ago when my port side retract refused to retract after a landing.  I had to cycle it 3 times to get it to extend during that last flight and after the landing it was just totally unresponsive.

So back on the bench, I started trying to troubleshoot the issue.  First off, you have to understand how everything goes together.  The retracts in the P-47 are simple units that require a separate controller unit that looks like this:

The retracts each only have 2 wires, a positive and a negative.   Each retract unit plugs into one of the back wheel  connections on the controller.  The controller has one servo lead for power and signal input to the controller.  This plugs directly into your receiver on whichever channel you chose to control the retractable landing gear. 

In my case, in order to simplify wiring to each wing, I have a wiring harness that allows for a single multipin connector to go to each wing rather than separate servo wires.  Since the harness consists of multiple wires and crimped on pins, etc… I first decided to eliminate the wiring harness in order to eliminate any possibility that a bad wire or crimp connection in the harness was the culprit.  That accomplished and no change in operation I tried swapping the port and starboard connections.  The failure still appeared to be in the port side unit.

At this point I got in contact with Extreme Flight to see what my options were.   I provided my troubleshooting results and awaited a response.  Although the response took several days I did eventually get an email back from a support person who questioned if I was certain the retract unit was failing and not the controller.  At this point I arranged a call with the support person and walked them through the steps I had taken and they agreed that I needed a new retract… which is unfortunately on back order… with no predicted ship date!!

They did agree that the retract set should be replaced under warranty and sent me confirmation of the order… but of course I was not hanging this plane up for the season without a fight!

So moving into some real testing I removed the offending retract from the port wing and the controller from the body and fished out a spare A123 flight pack and my trusty servo tester.   (Note: when I pulled the retract I was sure to use the retract wire to pull a string from the wing root out to the retract area so that replacement would be simple. ) 

First using the starboard wing to check my test bed, I confirmed I could cycle the working retract without an issue.  During this test I noticed that the controller has LEDs that cycle from green to red depending on which way the controller is trying to drive the gear.  The LED goes off once the retract hits its limits and (I presume) the controller senses an end point has been reached.  I’m guessing it senses the spike in current as the motor stalls and automatically shuts down.

I also measured the voltage being supplied by the controller and verified that the controller simply flips the polarity to the motor in order to reverse the direction when the servo signal goes from one end to the other.  Following up on that I started trying to establish whether the continuity of the wire was good all the way to the retract motor.  I stuck a couple of very fine pins into the wire up near the motor and tested for continuity from the connecot to that point.  This established both wires were good to that point so it was down to either the motor being bad/burned up/open or just a bad connection to the motor.  I measured the resistance of the complete working retract in the other wing and established a baseline of about 4.5 ohms was a normal working unit.  Testing the bad unit showed infinite resistance/an open circuit.  After I did this, I quickly realized the red wire had indeed broken loose inside the “can” that surrounds the motor and I was able to easily pull the wire out of the entry point to the can/motor housing.  The problem now was that the motor sits inside this can and has no screws, set screws or other obvious way to get it open!

Deciding that I had nothing to lose I started disassembling the retract mechanism.  

Once the screws on one side were removed it was simple to separate the motor assembly/screw/trunnion pin from the remainder of the servo.  Note that there are  ball bearings in the sides of the assembly so while mine easily stayed in place, I’d be gentle and try not to dislodge those if you ever have reason to dig this deep!

Once the motor can was loose in my hand I realized that if it were going to be possible to get inside the can and get to the solder connection point on the motor it had to be some sort of split/friction fit or two parts had to twist apart somehow.  I first took a razor knife and tried to split it along either of two lines around around the enclosure… neither yielded to my efforts.  Finally I grabbed the center of the can with a pair of pliers and tried twisting either end.  Finally the end nearest the trunnion pin rotated a bit and I was able to unscrew that part and slide the motor out from inside the rest of the assembly.

At this point it was possible (if difficult to manipulate due to just the small size of the solder tabs on the motor and gauge of wire) to re-solder the wire and test the operation.  Hooking the controller back up to my servo tester and operating the retract motor was again attempted and all went well.  Keep in mind the motor will just run continuously as there is nothing stopping the motor so no current surge to tell it to stop.  This is normal/expected operation in this state.  Also note that there is a spacer in the end of the can where the shaft extends out to the trunnion and the shaft of the motor is keyed into the threaded shaft so be careful when reassembling not to lose of those parts and to align the motor carefully so its keyed shaft fits correctly to the threaded rod end as you put things back together.  I was concerned that the wires might touch the can and short out the controller output as there is no obvious protection from this happening but it didn’t so I’m assuming the inside of the can on that end has some sort of clear insulator or other mechanism to prevent it even though I never figured out exactly what it is.

Once I completely re-assembled I took some steps to protect against another failure due to motion of that wire or strain on the wires.  First I coated the entry point with liquid electrical tape and let it set up.  

As you can see by the scars on the can, I marred it up just a bit with my pliers during the process but now that you know that the end cap nearest the pivot point is the one that unscrews, you could probably avoid this with some care and perhaps a wrap of tape around the can in strategic locations when disassembling.

Once that was accomplished (on both retracts) I mounted the retract back in the wing, used the pull string to get the wire properly routed.  At this point I pressed the wire up against the balsa sidewalls of the wheel well and applied a bit of glue to make sure no further physical strain could be applied to the wire at the entry point to the can.  As shipped that is just an entry hole with no grommet or strain relief of any type so I’m being doubly certain to protect it moving forward.

How will it hold up?  Is this the end of the retract issues on this bird??  Well we shall see, assuming I manage not to do anything stupid during my flights.  Let’s hope for the best.

I’m only now realizing that I have no idea what keeps the motor from spinning around in the can… I didn’t see an alignment pin or flat inside the back of the can etc… but it would seem there must be something there besides the wires that can’t rotate… I’m guessing there is something in the front area that accomplishes this.  Well that’s an investigation for another day and probably only if/when I get the new set or have to work on these again so lets hope that remain a mystery!

If you have this airplane or the Aces High FW-190 from Extreme Flight that looks to use similar retracts, I’d definitely address some sort of strain relief on your retracts to avoid similar issues.  Blue Skies.

 

Seagull Models T-6A Texan II

Early in 2020 I was wandering through a huge swap meet over in Dayton, Ohio and I chanced across two new-in-box 60″ish” size Seagull Models T-6A Texan IIs…  One was made up in a beautiful Red/White/Blue/Black and Silver scheme and the other in more of a gray camouflage pattern. 

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I admired the models and quickly decided they were not for me.  I kept telling myself that a T-6A is a jet trainer and surely would be fast and heavy and besides, what did I have for a power system?  They are a bit more unique though and the red/white/blue scheme sure looks nice… I almost didn’t make it past the table when the owner made an offer to let me have one for what couldn’t be more than 1/2 of the cost of a new model!!  I stuck my fingers in my ears and ran to the next set of tables… 

Fast forward a couple hours later and I’m about to finish my first lap around the meet when I noticed what looked like a NIB Hacker motor.  The gentleman explained he had bought it as a spare that he had never needed.  I had some recent experience with another Hacker that was part of one of the best E power setups I had ever operated so this looked tempting.  Again the price was right and this time I didn’t try too hard to resist.

Now armed with a high powered 6S power system (1250W continuous and able to easily handle 1600W) I realized I had the exact motor for the Texan II.  After a brisk walk and a quick negotiation I had the airplane as well.  Wait, what had I done!?  It is still a jet trainer.  I like lightweight, overpowered, nimble and aerobatic aircraft with simple fixed gear!!  Why did I buy this beautiful, sleek, heavy trainer with mechanical retracts??

Over the next couple weeks I worked my way through assembly of the T-6A.  Since my expectation was that this airplane would likely end up being something I’d only fly once in a while and probably end up selling to those who have more appreciation for “war birds” I decided to make sure I added most or all of the scale details (something I might normally skimp on) and try not to spend an inordinate amount of money assembling all the pieces and parts I would need.

With that in mind I installed the pitot tubes on the wings, the anti-static rods on the elevator  and even took the time to make a color change on one of pilot busts so that they wouldn’t look quite so much like twins!  I also took some extra time to apply the decals and even did some “base layer” covering work under the star and bar logos to help cover up the color change underneath and not allow it to show through.  I also opted to install the mechanical retracts where I would normally have spent the $300+ to purchase electrics.  The mechanicals are going to cost me more like $50 to install, mostly the cost of a retract servo.

The first pleasant surprise was how well the retracts worked with nice direct routing of the linkages.  Ok, so I’m not a big fan of the plastic inserts for the wheel wells, but with some care they at least are a decent color and fit.  Again, I’m not a big fan of a once piece wing but the upside is the  simple retract linkage geometry and the need for only 1 servo to service both mains.

Once I got it all assembled I was back to the overall look.  I love the lines of the Texan II, the PC-9, and similar aircraft and this one has a great color scheme… but I wasn’t getting my hopes up on flying characteristics so with little fanfare I took it out to the field and with only a couple of friends present I flew it for the first time.  All I can say is wow!  This thing is certainly a warbird.  It’s not light and flies much better with a little more throttle… she’s no floater… but it feels like it is on rails in the air and has enough wing to handle the weight so just by keeping a modicum of speed on the bird, she flies great!

Since that day I have probably put 30 more flights on the airplane and I’ve had zero issues with it.  It flies really well and it with all the scale touches it looks great in the air.  I don’t recall flying it without someone commenting on how nice it looks.  I’ve switched out to a very slightly less efficient 4 blade propeller for even more appropriate scale looks on the ground and I’ve had a few of the scale details get broken during transport and assembly but otherwise it has so far been a great airplane.

I created some protective covers out of foam, cardboard and tape to protect several of the protrusions… antennas, static rods, etc… and had to create some replacements once in a while the flight characteristics have been very pleasing and I do enjoy flying it… and lets admit it… the comments and attention it gets!  I have a Styrofoam holder (cut with a foam cutter from a shipping container for frozen food) for the body and a wing bag for the one piece wing that helps keep it all safe during transport and those have cut down on the issues.

So in summary, I’d recommend the plane to anyone interested in a nice psuedo scale attractive airplane that wants to get into warbird type aircraft.  Its a nice step from sport planes into that realm and you will enjoy flying it as long as you remember what it is and fly it accordingly.  3D is not ever going to be its strong point, but sleek lines and scale aerobatics are done with ease and look really nice in this bird.  It has earned a place in the hangar at least for now.

 

 

 

New Hangar 9 P-47 67″ ARF… One flight and gone.

My first attempt at a replacement for my late lamented Top Flite is the H9 20cc size P47D 

P-47D Thunderbolt 20cc ARF, 67"

I transplanted all of my radio gear, servos etc… from the Top Flite and contemplated a number of updates/changes etc… 

Should I try to 3D print a better cockpit?  The provided instrument panel in particular looks like it could only be accurate if the instruments were updated to 2020 standards!  I decided to go ahead with the supplied until I decided how much I liked this particular model. 

I also contemplated and decided to put my retracts in the wing and even ordered a retractable tail gear.  When that didn’t fit I tried another and spent a fair amount of time fabricating linkage to make it work correctly.  Don’t believe the Horizon web site…  The nose retract they recommend simply can’t work as the tailwheel retract for this airplane!

I did find some plans for and 3D printed some wire guides to make wiring the bird easier and then crimped up some multi-connectors to make it hassle and error free.

After all that the bird was beautiful but heavy… compared to my Top Flite this bird was 3 lbs heavier and when I flew it I immediately found that it just didn’t track like the Top Flite and the thrust to weight ratio is anemic as well.  The extra 3 or 4 inches of wingspan just can’t compensate for the increased weight.  Now maybe my repaired power system is not operating as it was…. I don’t believe so but it is possible.  Or maybe the power system is just to small for this slightly larger WS and appreciably heavier craft.  Again, perhaps but there is no way the recommended Power 60 would be better.  I love the power 60.  It’s an underrated and amazing motor, but it isn’t going to outperform the Hacker A60. 

I flew one flight on the airplane and was so disappointed I took the airplane home and stripped my radio gear, retracts, etc… aside from the servos and wire guides… out so I could put it up for sale immediately.  Eventually a friend of mine purchased the plane and he and I are installing a DLE-20 he has.  Maybe with that power plant it will find a new lease on life.

For me, I have my eye on an airplane that is similar in size and weight to the Top Flite…  Hopefully my third P47 will be a charm!  For me, the H9 is to heavy for its size to fly the way I like.  I suspect that many warbird guys would love this plane, but anything I fly needs to fly well first.  Looks, scale detail, etc… all have to take a backseat and this was not my impression of the H9.

Hacker A60 Repair

After the great NX10 failure of July 2021 I found myself with a Hacker A60-5S V2 motor with a bent shaft…  I had heard that parts were available for these motors so I searched and sure enough I found the replacement shaft readily available and at a pretty reasonable price… especially considering how well the motor had run and the higher initial cost of the motor.  I had expected worse so I went ahead and ordered the replacement shaft.

I had included a request for information on the replacement procedure when I ordered the shaft so when it appeared on my doorstep in just a couple days I was pleased until I realized that there were no directions included.  None on the website either and after searching the web thoroughly it didn’t appear there were any videos or descriptions either.  Not even a good exploded view of the motor was to be found!

This left me in a bit of a quandary.  After staring intently for a couple days at the motor and replacement shaft while they sat patiently on  a corner of my desk I eventually unscrewed the bolt that seemed to be some sort of bearing retainer at the back end of the shaft.  There was a thick non-ferrous washer underneath that came off with it but it didn’t just fall apart at this point so I examined it some more.  Seeing that here was a threaded hole and a matching allen bolt/set screw in the replacement shaft package I soon surmised that this set screw was hiding just behind the front plate of the motor and could be reached with an allen wrench via one of the vent holes on the sides of the motor.  With the help of some very bright lighting to make sure I guided the allen wrench to the screw correctly and that making sure I had a nice fit, I managed to unscrew that as well and fish it out of the motor.

At this point I could see no reason the shaft shouldn’t slide out but tugging and pulling (and cursing) didn’t seem to make it happen so I set it down for another bout of staring and perusing of the internet.  There were several videos of shaft replacements for electric motors but none of this model and many talked about pushing the shaft the wrong way causing damage to the coils in the motors… yikes!

A couple days more passed and I decided it was time to just take the plunge.  using a 1/4″ drive socket that happened to taper down to the perfect size to press this shaft out I placed the motor face down on my drill press table with the shaft through the hole… I was going to try to press it out forward as I had seen one other Hacker done in a video (a totally different looking motor but hey I only had two choices).  I had heard a drill press is a pretty good arbor press substitute so I started putting some pressure on the shaft which seemed pretty determined to stay right where it was.  Wondering if I might be purchasing a new motor soon I put a bit more pressure on it and… it moved!

I had to find another rod to push the shaft through a bit more before it started to move a bit more freely and I could press it the rest of the way out by hand.  Finally I had something that looked like this.

After a fair amount of cleaning with high pressure air and a little careful brushing with a toothbrush I grabbed the new shaft and discovered it’s a little shorter than the old one.

The important dimension however from the back of the shaft to the set screw was the same so not a big issue.   There was really only one more big “trick” I had to find out the hard way and that was a little issue of aligning the threaded hole up with the hole in the front plate so the set screw would go back in place easily.  Since it’s down in a dark hole when reassembled it took a bit of finagling but I eventually managed to get it all aligned properly and the motor looks like new and seems to run smoothly once again.

I’m working on the replacement for the Top Flite P47 now… of course a new Jug is in the works and now I have the perfect motor for the job! 

Spektrum NX10 failure analysis and repair

In a previous post I reported on the demise of one of my favorite airplanes.  The Top Flight P47 60-90 size ARF.  The cause of that crash was that my Spektrum NX10 powered off mid-flight.  This is disappointing as I have run the NX for several months and been extremely happy with it.  The radio link to all of the planes as I  flew them has always been rock solid… well at least while the radio was on!

After the crash, there was no doubt the radio had turned off unexpectedly.  So began the investigation.  I posted online about the failure and found just two folks who had claimed to have something similar occur and none had an occurrence during flight. 

Thinking back, I honestly believe I may have seen it happen once on the bench shortly after first receiving the radio but at the time I was on very early code and was still learning to use the thing.  As it happened I was working on a setup of an airplane and turned away for a few seconds to check something else behind me… an email arriving on my computer or whatever… and when I turned back the radio was off.  I was so uncertain at the time as to the sequence of events that I passed it off as “perhaps I turned it off without thinking or realizing it when I got distracted”.  I really couldn’t believe the radio turned itself off and I never saw it again through setting up 20 or so airplanes on it, multiple upgrades, template creations and many flights on many airplanes later I hadn’t seen it again so had forgotten about it and moved on… until it did it again and my plane crashed.

Online I got the usual advice and questions… folks trying to helpful asking about battery state, shake tests, testing the on/off switch, etc… and I did as many of them as I could justify or understand to no avail.  I tried to jiggle the battery and connector particularly looking for an intermittent connection from the battery but it stayed on solid through all the shaking, wire twisting, switch tapping etc… that I could figure a way to inflict on it.  In a few days I acceded to inevitable and sent it off for repair with fingers crossed.  I spent years troubleshooting network for a living so I understand troubleshooting software and hardware systems like this when there is no no repeatable test case and no apparent error (other than a pile of wreckage) to be seen is an extremely trying task so I held little hope.

Now on the forums there are several very respected folks who monitor and comment on things and one is a gentleman who actually works on the software team for the NX series radios.  Andy, like others, recommended sending it in and contacting them to discuss it.  After the radio had been in their hands for a few days I reached out to him to try to figure out the easiest way to reach whomever was testing my radio.  I knew that the best chance of getting a fix was to give them as much information as possible and the online form only allows so many characters so I gave Andy a complete description of the issue and asked for his advice on how to get this to the correct people.  I also tried to impress on Andy that I really wanted a resolution beyond “no problem found” as I would never commit another airplane to flight with that radio unless we could determine a cause and apply an appropriate fix.  I also explained that I have been a pretty loyal Spektrum user for many years now and have purchased many Spektrum radios and spend a fair amount of time helping my fellow club members get the most from their Spektrum radios.  I really didn’t want this story to end with “…and that is why I have a $500 radio that sits in the corner and gathers dust”.  Returning it to me in that state would be a waste of postage.  Unsaleable and unusable…

Just a day later I got the notice that Horizon had sent me a shipment.  I feared the worst… then came the invoice for $0 and a note that they had decided to simply replace my NX10 under warranty!  Is this the best of all outcomes… no.  It is however the best response that I think Horizon had available to them and I commend them for excellent service once again.  I’m sure they tested my radio and had no way to recreate my issue.  I ran it for months and only saw it happen (maybe) twice and the circumstances of each were different.  I’m sure both Horizon and I are hoping it was simply a one in a million intermittent hardware issue and neither of us will ever hear anything like it again.

Horizon even went so far as to transfer all my models over to the new radio and upgrade the software to the very latest version.  They also sent me a complete new kit… radio, battery, strap, etc… all the stuff that comes with a new in the box system…. even though I had only sent them my bare radio minus batteries etc…  Of course they cannot replace my airplane.  That is simply asking to much and lets face it; if you can’t handle an occasional loss of an airplane you probably need to get out of the hobby.  They did more than I think is reasonable to expect in a bad situation and I appreciate that they are electing to take care of a loyal customer such as myself.  I have experienced much less satisfactory service from companies who have gotten a lot more of my money but Horizon seems to get it right more often than not so I will continue to support them and spend my money with them as often as I can.  Thanks to Andy and the rest of the team there.  You guys do it right.  Thanks again.

So I now have a brand new NX10 and am starting to get my planes bound to it and ready to go.  My Timber X is back on the NX10 and flew well on the first couple of test flights…. It may be a bit before I put the 12S powered Aerobat or the 1/4 scale cub back in the sky with the new radio, but as my confidence in the radio recovers, I’ll be moving everything back over.  Fingers crossed this will be the final chapter in this saga.

Top Flite 60-90 size P47 ARF… Final flight. Spektrum NX10 failure investigation begins.

My Top Flite P47 was a super flying airplane with a great power system and has been performing flawlessly.  I have been testing out some different props to determine best mix of power, speed and flight times attainable.  Have broken a few props but otherwise she was running great.

Unfortunately all good things must end and a couple weeks ago she ended a flight looking like this.

No photo description available.

Here’s how it went.  On takeoff, I started a nice steady climb and flipped both the landing gear up and flaps up switch.  As you can tell in this photo, the gear cycled all the way up successfully and I’m confident the flaps did as well from the way the it was flying.  I then made a left turn and was nearly in knife edge when I suddenly realized I was no longer in control of the airplane.  The plane was sliding on its wingtip toward the ground and nothing I could do with the sticks had any effect.  Being electric and a good way out I heard nothing other than a sickening crunch after it disappeared below the corn stalks…

In disgust I dropped my gaze to my radio and was surprised to discover there was no display and no lights whatsoever!  I removed my sun glasses to be sure and verified the radio was indeed off.  After walking back to a seating area (I needed to sit down) I turned the radio back on and it powered up normally and showed the battery was at 4.0 volts which is in the range of 80-90% of it’s full charge state… i.e. the transmitter battery is not dead or even low.  I then tried to figure out if my neck strap, clip or some placement of my hands could have turned the radio off and I cannot imagine how to make that happen while going through the maneuvers that I performed.  It takes a good 4-5 seconds of steady pressure on the power button to turn off the radio and in that time period before the plane stopped flying I had flipped two switches and moved both sticks to adjust throttle and perform my turn.  Try that and tell me if you can do it, even if you try!

After a long walk in the corn locating the “remains” I started reclaiming all the parts and considering the wingtip and nose in a near knife edge collision to the ground, the components aside from the airframe faired as well as could be expected.  The speed controller had a fan mounted on it… That plastic frame did not survive but the replacement is $10 and the speed controller itself has tested out to be in good condition so far and does not have a mark on it otherwise.  The receiver is likewise undamaged and tests good as do all the servos.  The motor had the worst result, being a bit dirt caked and the main shaft turned out to be bent.  I’ll post on that separately.  The retracts, as you can see in the photo were safely retracted before the loss of signal occurred and also seem to be unscathed.  Even the two batteries (a 6S 5000 and a 2S 5000 run in series) look in good shape and still charge as before.  As I said, things survived pretty well aside from the air frame.  It is a total loss with only the tail surfaces seemingly intact.

As you can imagine, this started a serious investigation into why the radio shut down.  I’ll post a new entry about that soon.

So ends my favorite war bird to date.  There will be a replacement of some sort soon!  Here’s hoping your flights are more successful than this one was.

 

Comparison – Night Vapor versus UMX Night Vapor

I have owned a Parkzone Night Vapor since not long after they first shipped.

ParkZone Night Vapor RTF [PKZU1100] | Airplanes - AMain ...

I’m not saying I’ve only owned one in all that time… I’m guessing 3-5 have passed through my hands.  One tried to fly just a little higher than a hovering helicopter, another had an unfortunate incident getting hung up in the net of an indoor soccer field and was heavily damaged during retrieval…  And one just  eventually had so much tape and added glue on it that it just flew like a brick.  Parts of that one still survive in my parts drawer to this day.

The Night Vapor was a fun, super floater that almost anyone could fly or even learn how to fly on.  A year or two into my run of Night Vapors (that doesn’t sound fun??) we discovered that the motor from the Parkzone Cub fit into this airplane and gave it a nice boost in power allowing for prop hangs, awesome slow high alpha and great climb rates with only a minor penalty in flight duration…. so that is the setup I’ve been flying ever since.  The only drawback to this seemed to be that you could stress the airframe enough to make it twist and become a bit erratic if you used to much speed/power… especially in a dive.  That is a very minor issue and easily avoided.

My current iteration of the Night Vapor is less than a year old but when I found out that Horizon had decide to do a “respin” on the Night Vapor I quickly decided I had to get one.  Here they are on my bench side by side.

  So here are the differences in the two in a static comparison.

  1.  The new NV is obviously done up in a different color scheme.  As far as covering material, wing area, tail area, etc… they appear to be sized and constructed identically aside from the color and frame differences noted below.
  2. The frame of each is identical with the following exceptions.  Most of the parts look to be interchangeable.
    1. The new UMX has wire main landing gear legs instead of the CF on the old.
    2. The new UMX has additional bracing from the body to the first rib on each side, near both the leading edge and trailing edge of the wing.  You can see these here.
    3. There is a larger frame/plate to hold the new receiver/servo “brick” in the UMX
    4. The new aircraft weighs .73 ounces versus the old aircraft at .57

Other differences of note:

The old PZ had 6 LEDs.  3 on the front of the wing, two on the back and one further back on the bottom of the tail boom area.  The new UMX NV has one in front, two wing tip lights and one on the tail boom.  The LEDs on the new airplane allows for some programming of the lights for different color combinations (White, Red, Purple, Blue, Green or Yellow) on the front and back lights, each independent of the other.  You can also have each solid on or a slow strobing affect.   This is easily accomplished from your transmitter.  The wing tip lights are green starboard and red to port with no adjustment available.  They are synchronized in a blink-blink-off pattern which also is not adjustable.

Flight wise the new airplane does fly just a bit heavier than the old plane.  To me it is noticeable but not offensive.  All up with a battery the difference is around 20-25% heavier for the new plane so it makes sense that it would be but the new plane is still very much a floater and the AS3X definitely helps around those pesky air vents, prop wash from other airplanes, etc…  and the extra wing bracing helps limit twist and flex in the wing when you stress the airframe a bit with those high power dives or speed bursts that are bound to happen!

I like the new landing gear as well.  The wire springs back nicely and doesn’t have a tendency to shatter like I’ve seen happen often (only once to me) and having the front and back lights be customizable is a nice touch.

In my opinion AS3X and SAFE are obviously a bit of overkill on an airplane like this but the telemetry feedback is really nice to have and has me wondering how many less batteries I might purchase over the next couple years if I actually pay attention to the warnings I have programmed!  Not sure how likely that is though as I never want to land this airplane except to show off my hand catch skills (don’t tell AMA) so I will probably continue to run most of my batteries to exhaustion.

The plane does do some pulsing of the motor as you fly the battery down to around 3.3V so you don’t have to rely on telemetry warnings.  Shut down comes at around 3.1V and once it has occured there is no restarting the motor until the battery is unplugged and replaced (presumably with a charged specimen!) .

After flying it stock a few flights I have now swapped in the motor from my old NV which is really the old cub motor I mentioned earlier.   I hope it will do for this new UMX NV what it did for the old one.  My worry is that these are brushed motors and I wonder how much longer it will last.  Horizon is not typically forthcoming on specs on their electric motors especially these micros so I have little hope I’d ever be able to replace this motor when it’s time has come as the motor for the old cub is no longer available either…  That will be a sad day.

So my feelings on the new NV are mixed… but weighing toward the positive.  I wish they had given it something equivalent to the cub motor to start with, especially with the increased weight but it sill flies crazy lite so it’s not a big issue and the added features are nice additions.  I have no qualms about giving up my old NV… I think this will be a worthy successor.

 

 

 

Hangar 9 Carbon Cub 15cc ARF … Part 3

In part 2 of my commentary and running monologue on the Hangar 9 Carbon Cub, I mentioned that I would cover the bottom vent that I added and some other mods so I will show you a couple of those here as well as try to relate my sense of how she flies.  First the build and modifications update.

Bottom Vent

Looking at the cub I realized there is not a lot of accommodation for air flow and even if it isn’t much I’d like to have at least a modicum of air passing over my batteries inside the cockpit area.  So without just cutting open a whole section between formers/bulkheads in the bottom of the tail I needed another solution.  What I came up with was to cut open a section in the only solid area behind the cockpit, which is the hatch for servo access.  I happened to have some louvers laying around that I picked up at a swap meet so I cut an appropriate sized hole and drilled a few holes for button head #2 screws and created a nice louvered exhaust vent.  It’s very nice looking (even if not quite scale!) and looks like it belongs there.  Was it enough exit area…  well read on.

Top Hatch blows off!

Taxiing out for the first flight on the airplane, everything seemed great.  I had done a balance check, the prop seemed to be well balanced, producing a minimum of vibration, all the surfaces were moving in the proper direction and with the proper authority…  Nothing left to do but fly.  Unfortunately upon reaching about half throttle, about 10 feet into the takeoff roll the top hatch that I had created decided to eject.  Testing a second time showed the same issue.  It hadn’t been jolted loose on a bump either it was simply being swept up by some combination of the air moving over the top of the wing and the air pressure forming inside the plane as the motor forced air into the various openings in the firewall.  While the louvers I had installed on the bottom of the plane might insure a good vacuum to pull some air past the batteries once she was in flight, they didn’t do enough while the plane was just starting to roll to avoid the top hatch getting popped open.  For the day, I simply applied some box tape along the front and rear edge of the hatch and things were fine from that point on.  For future flights I had to do something to make the latch mechanism a bit stronger.  Clearly the magnets I had in place were insufficient.

Before the next flight I eliminated the magnet and screw head that I had used to secure the hatch and cut a groove in the wood and created a tab using a servo horn to form a rotating latch that would insure the hatch stayed in place.  Ten or so flights later, this seems to work well.

Servo arm loose on rudder!

The final lesson re-learned on the second or third flight of maiden day for the Carbon Cub was that you should always tighten all the screws and check all of your servo arms, linkages, etc… before flying.  The rudder and elevator servos are under that bottom hatch and so not observable without unscrewing and removing the bottom hatch.  Apparently, when I was setting up the plane, adjusting throws and linkages and such I had neglected to make sure all of these were tight.  The servo arms are metal and are a decent fit but slightly loose on the servo shaft.  If the teeth are engaged there is zero slop but if you don’t tighten up the servo shaft screw the arm will slip off and rotate out of place… especially when sitting in the trailer, bouncing down the road under the force of gravity I imagine?

So 2 or 3 flights in was doing some stall turns and I was getting adjusted to just the right inputs to get an acceptable looking maneuver when it flopped out of one of my attempts.  Since I was low on battery I decided to come down and check out my throws and see if I could improve on the next flight.  When I landed,  my plane was crabbing slightly toward the pit area so as soon as the tail dropped down to join the mains on the runway I started to feed in just a touch of rudder to straighten the roll out… It wasn’t enough so I pushed in more but nothing occurred.  I was far to close to the pilot line and rolling fairly slowly so throttling up without being able to change heading was not an option, especially with a plane I had only a couple flights on and knowing someone was occupying the flight station I was quickly approaching.  Instead I hit throttle kill and watched it roll up and bump the flight station.   Other than a startled fellow pilot, no harm was done.  He maintained focus and control of his airplane and I went down and apologetically retrieved my errant bird.

Of course as soon as I saw the rudder “freely” swinging in the breeze I dug in and found the culprit quickly.  I applied just a small amount of nail polish (thread locker is known to attack some of the “plastics” used in servos… Hitec Karbonite in particular but others as well… so I largely avoid it around my servos) and tightened the screw and have had no further issues with this connection since.

Flying with the Power 60 on 6S

The Hangar 9 team recommends the Power 60 for the Carbon Cub if you are going electric and I think they have a pretty good combo here.  With my 6S 5000mah packs I believe the plane is capable of handling about anything the real world plane can do, and perhaps a bit more.  This does NOT include an unlimited vertical climb with out assistance from the wings but it is not far from it. 

My impression is the plane flies just a little “heavy” on the wing and thus requires a bit more speed than I would like, but keep in mind I fly mostly very light, overpowered aircraft like my EF Laser on an Xpwer 35 and 12S, the Timber X on 4S, the Uproar on 4S, etc…  For a war bird guy, this thing would probably feel lighter on the wing than most and most scale pilots I suspect would see it as being “about right”.  You have to remember that while it has “Cub” in the name it is NOT the ubiquitous yellow J-3.  It is not a floater that is hard to get on the ground but it is predictable and smooth.  If you incorporate the flaps into your landings (as you should), the plane will land at a very manageable moderate speed with only a little time spent with the tail still flying after touchdown.  It’s not a total kitten either in the air or on the ground but in return it is a very capable flyer and a beautiful airplane both close up and in the air.

Top Flite 60-90 size P47 ARF… Gas to Electric P4: Flying the P47 with Electric Power!

After completing the power conversion of the Top Flite P47 to electric power it was not long before I had the opportunity to put some flight time on the bird.  In the course of a couple weeks I put around 10 flights on the Jug.  I’ll relate some of the issues and fixes, impressions and performance information in this article.  I don’t recall exactly in what order all this occurred or was measured so I’ll just hit the various topics without trying for any sort of linear time line… my memory just isn’t that good!

First, I’ll draw a comparison to my “outgoing” Thunderbolt, the FMS 1500mm P47.  While I’ve always enjoyed flying the FMS aircraft and would recommend it as a smooth and good flying airplane, I prefer the Top Flite in the air. 

While just a few inches larger in wingspan and several pounds heavier, it just seems to fly more like a warbird… in only the best ways. 

Neither are hard to land.  The FMS can land slower due to wing loading but also due to just being a lighter aircraft it tends to bounce around a bit more.  The Top Flite likes to land a bit hotter, even with flaps but it settles in nice and rarely wants to bounce.  The FMS may be a bit more aerobatic, but either can do anything a real jug can do plus more and the Top Flite seems to just track better and slice through the wind better.  Everything it does is smooth where the FMS can occasionally be a bit more twitchy.  Not terribly so, but noticeable if you fly them back to back.

Of course it may not be a fair comparison considering the power system differences but my Top Flite is certainly faster and looks it even though it is a bit larger (my experience is larger planes actually look slower).  I always thought the FMS looked a bit slow in the air considering it’s a fighter plane.  It certainly flies well even at slower speeds which is nice on approach but without making some changes it was never going to keep up with the Top Flite.

The other big difference between the two is flight time.  Unexpectedly the bigger Top Flite can loiter much longer than the FMS.  I figured using an 8S system would give me higher speed but at the cost of weight (the Top Flite is heavier even if it was only running a 6S) which would balance out and result in the same 6 minutes or so down to about 30% in the packs that the FMS typically did.  I’m running the same 5000mah capacity, just more cells.  Instead, as I recall, I landed at 6 minutes and had 60% left in the batteries on the first couple flights!!  Now on those first couple flights, I probably wasn’t pushing it quite as much as I normally do the FMS but the flights since have convinced me to up my timer to 7 minutes and even with some more aggressive flying I am landing with 45% or more of the battery capacity remaining… I’m not really sure why I get such great efficiency but I’m going to try bumping up the prop size a bit to get a bit more punch and see how it affects things.  Nothing is getting overly hot as is so I’m hoping for even more power and still having a 7 minute flight to 35% on the batteries…. we’ll see.

Aside from the flying characteristics I have made a few other changes/repairs on the Top Flite P47.  After these changes it has completely replaced the FMS which I recently sold to another pilot. 

First of all, I noticed that one of the flaps on the Top Flite could only extend to perhaps half of the recommended travel so I had to setup with that as the max flap throw.  On the first flap assisted takeoff (with about 65% of available travel), all seemed OK but on landing with full extension I was disappointed with the effect.  Other flap equipped planes I’ve flown certainly slowed up and assumed a nice sink rate where the P47 did not slow as much as I was hoping with the available travel.  On closer examination it certainly appeared whomever had glued in the hinges had gotten them a bit to tight, which was causing the push point hinges to push against parts of the wing trailing edge.  With some judicious trimming I got closer to 75% of recommended travel but no more.  It was all I could get without cutting the hinges and starting over.  Happily, it was enough that on the next landing the Jug slowed up significantly and dropped in a bit slower.  I wouldn’t mind a bit more flap but it’s now very manageable on landing.  It likes to land a bit fast, but that is very typical warbird like flying.

I still land a bit faster than I really have to as I’m really still just getting familiar with the way it flies and particularly how it lands.  At one point that certainly bit me.  We have a nice Geotex runway at our field about 250′ long and I love to land on it when I can.  Partly, I just like to control the plane and land it where I choose versus just letting it land.  I also feel like the landing gear is less stressed when it doesn’t have to drag through the grass.  Putting the plane down “on target” is a good skill to perfect as it can come in very handy when conditions are less than ideal or when landing at facilities that don’t boast our 700′ well manicured grass runway with almost unlimited approaches!  On the particular landing in question, I came down a bit fast due to some crosswinds (it’s easier to bring it down fast and maintain control all the way to the ground) and I was rolling tail high, holding a bit of rudder to offset the wind when I rolled across the one flaw in our Geotex runway… a little ridge where the grass edge of the runway used to be.  This popped the plane back up in the air just long enough to carry the plane into the grass.  Once in the grass I tried to let it settle in but the sudden transition from tail high rolling on grass to the same in the grass caused a quick nose down rotation as the wheels touched back down and she did a flip over on her back…. just hard enough to snap the top couple inches off the rudder!  In retrospect I should probably have juiced it a bit and slowed my decent or even gone around but all in all it was ugly and embarrassing but  it was a fairly clean break and an easy repair.  It also broke the prop which was more expensive to fix but otherwise she was unhurt.

The other occurrence during these first flights was when the battery hatch decided to do its own “off field landing”.  I was not a fan of having magnets in the front of the hatch and pins in the rear as this was built but I decided to give it a try.  In order to keep the hatch in place I took the liberty of attaching a couple more magnets inside the body to increase the pull of the existing setup.  This certainly seemed to help it really snap into place, but apparently that was not enough as around flight number 4 I landed with no hatch in sight!  The really odd part was that I didn’t get unusually high or far away and at least 2 other people will swear they never looked away during the flight, yet all agreed the hatch was attached on takeoff and no one saw it come off but it surely was not on the plane on landing!  Again, I was frustrated as the hatch was such a nice feature and creating a proper curved replacement was not something I really wanted to spend a lot of time on but I had no real choice.  The new hatch now has this latch centered on the leading edge and I don’t believe it is going to part ways quite so easily in the future.

With that taken care of there are a few “clean-up” items I want to address.  The cowl is a bit hacked up as it was cut to allow for the DLE-20 and of course you can’t buy a spare for a plane that hasn’t been produced in a number of years…  I’ll have to figure out if I can find something available that fits, or if I will try to repair what I have.

A second item is that the cockpit is empty and I would love to find a nice pilot figure that looks appropriate in size and style.  I’m eyeing some “Benchcraft” warbird busts from Motion RC.  At the price, I will probably order 1 or 2 and see what looks good. 

In the meantime this is simply an excellent flying airplane and a great power setup that I’m really enjoying.  I’m very happy that the stars seemed to have aligned on this airplane.

Top Flite 60-90 size P47 ARF… Gas to Electric P3: Motors, Speed Controllers and Batteries

This is part 3 on my journey of converting this aircraft to Electric power.  To see the previous post on the topic, click here.  

As I have mentioned previously, I had picked up a nice Hacker motor from a flying club member and it seemed like it might work out as a power plant for this aircraft.  I needed to get that mounted and also figure out what sort of ESC might be appropriate as well as selecting an appropriate battery and then figure out placement and mounting for all of that.  So here was my process.

First I researched the airplane, including expected weight, wing area and ground clearance.  I also read a bit on any balance issues folks reported to see if I was likely to need nose weight or tail weight and the weight of the suggested power plants.  Armed with that I logged into ECalc and filled in the blanks with the wing area, weight and the motor type I had on hand.  I then started plugging in appropriate speed controllers, props and battery combinations to see what I was going to need to get a good power to weight ratio.  Something in the 1.2:1 or higher range seemed like a good goal for a fighter aircraft like the P47!

I like to keep the voltage high and amperage low in an RC aircraft power system.  Higher amperage is hard to accommodate as most of our common connectors are not rated for it.  If you overtax them, they get hot and waste power and eventually this causes a catastrophic failure.  For similar reasons, our LiPo batteries will fail quicker when you run demand high current rates from them, plus they cost and weigh more as you try to accomplish this with batteries that have a higher “C” rating. 

A little rant about LiPo C ratings…   Feel free to skip the next two paragraphs if you like.

In general, C ratings are useful only in that a higher C rating within a manufacturer battery line indicates the ability to supply more current without damage to the battery than the batteries with lower C ratings.  Beyond that they are deceptive at best and almost useless for comparison between manufacturers.  Feel free to disagree but I am convinced that this is the state of things at this time and don’t expect it to change anytime soon so don’t put to much faith in C ratings.

So, while my large aircraft could (according to the manufacturer C rating) run on 20C cells, typically 40C cells get pretty hot and therefore fail sooner rather than later.  The 50-60C packs simply perform better, don’t get as hot and outlast the lower C ratings… at least in the brands I most commonly run.  I don’t bother to purchase from companies who advertise 100C and better as they are pure fiction in my opinion.  A continuous draw at the advertised C rating is almost always a recipe for battery destruction in very short order and in the case of larger capacity packs is likely going to result in batteries dying from internally generated heat and wires/connectors or something similar failing anyway as the system quite literally “melts down”!  It’s a joke to say you have a 4000mah 100C pack (that equates to 400A draw) and then putting a connector on it that is rated to handle, maybe 100A for short periods before it literally “melts down”!   The cells in these packs might handle 150A draw with perfect ventilation but I doubt it.  OK, rant over.

Back to sizing the system I came to the conclusion that running an 8S system with a 16×10 prop would be a good starting point with a predicted 1.3:1 thrust ratio.  Partly this choice was based on the power I wanted and partly due to available speed controllers.  Spektrum had just released a line of Avian speed controllers and one of them was capable of 8S (which I estimated was close to the biggest packs I could likely get into the airplane) and was rated at 80A continuous with 100A peaks which was as much as I really wanted to run through the EC5 connectors anyway!  It was also far less expensive than the Castle Creations options in this same range and had Telemetry built in that I was going to want.  I can do that with Castle Creations and most other speed controllers as well, but with even more expense.  This setup also allowed me to prop up a bit for additional power if I later decided I needed to, which is always a nice option to have.  The tradeoff if I did was that a 16×10 would likely give me 7 minutes or more in the air with a 5000mah pack while a 17×10 or 18×10 would start to cut into that as they would draw more amps.

In order to take advantage of the telemetry capabilities I wanted to access from the Avian speed controller I also would have to acquire a new receiver.  I settled on a new AR6610T.  That wouldn’t be a terrible expense as I had a project that needed a simple receiver like what was currently installed in the P47 so one way or another I was going to be buying one soon anyway.

Decisions made, I placed some orders and started looking to mount the motor.   This came down to simply finding the right size spacers and then a hole for the wires to get through the firewall and some judicious trimming of the dummy engine.  

The spacer length I needed turned out to be the same as some readily available standoffs for a DLE 30, which simplified things a bit.  

Then to allow the prop to clear the cowl I added a couple washers behind the prop collet assembly.

Accommodating an already existing 6S 5000mah pack plus a 2 cell pack of equal size and rating in series (which the speed controller accommodates simply as it already has a series harness attached!) was a bit tricky as the tray exposed under that hatch was simply too shallow for this setup and I didn’t want to buy several batteries for which I would have no other use.  Here’s the original space.

So, I did some cutting and regluing to create a “ramp” that allowed for easy insertion of some of the packs I had.  I had already determined that having the batteries up against the back of the firewall was appropriate to get the balance where I wanted it and while it was a bit tricky to cut out, the existing structure, thusly relocated, works well for the new battery compartment “floor”.

I needed some 2S “booster” packs (as I think of them) to add to my 6S packs in order to run an 8S system so I started looking for something appropriate.  I ended up with some APower branded 5000mah, 60C rated packs I picked up from RCBatteriesusa based in Arizona.  I had read an article about the company recently and decided to give them a try.  They are not the cheapest place to buy packs, but not at the very high end either and offer a good warranty as well as being reputed to have top notch service.  The folks there were as good as advertised in taking care of what I wanted, including the fitting of my requested EC-5 connector even though that was not an option on the web site when I first started shopping.  At no additional cost I might add.  After unpacking, examination and a few cycles they appear to be high quality.

That about covers the power system… I think.  Next time I’ll try to run down my experiences and impressions of the first dozen or so flights.