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mechmove's blog
Posted by mechmove | Feb 03, 2013 @ 08:10 PM | 1,454 Views
I managed a few flights with my Supra and Ava electric gliders over the last 2 mos. For the first time, I started downloading Castle ICE data from my Supra after each flight. The only headache is connecting the center lead on the speed controller. Since I have a 4 cell receiver pack, disconnect immediately afterwards is a must.

Main reason to start using the Castlelink was to adjust for a stronger prop brake. For the first few flights, the brake wouldn't even engage after the motor is stopped. Prior to ICE, going through the programming sequence meant becoming a human BEEP counter. Why bother. Now I can analyze data after the fact: maximum current drain was 95 amps, with max temp anywhere from 125 to 140 F and ~89,000 RPMs.

Who could ever guess an electric motor can produce such a high rate of turns?

I have been struggling with pitch stability on the Supra for quite some time. At first I though the CG might have been changing, but I know this cannot be happening. The elevator connections are secure. One thing I was doing was launching leaving the trim set from the last landing, which is set to "nose very high". No wonder I was having wild pitching moments on takeoff.

I know as a private SEL pilot we always set the trim to takeoff position after landing. Trim is then adjusted during the climb out and different phases of flight.

So why not launch an RC plane in the same fashion?

So for the first time, I zero the trim to neutral for the initial...Continue Reading
Posted by mechmove | Jun 21, 2012 @ 09:53 AM | 1,934 Views
After burning out my Phoenix 125 speed controller in my Supra, I decided to go with a lighter setup: NeuMotor 1110/1Y/6.7, ICE 100, and RF 16x10. The 61gm counter weight on the tail is down to 14 gms.

All up flying weight is now 86 oz, still heavy, but there is plenty of horse power. Gary at SoaringUSA gave me some good advice : I opened up the nose cone for better ventilation. Also disposed of the Deans connectors for the gold plated bullet connectors. Slightly more hassle to ensure the heat shrink is applied correctly, but those won't burn up due to high current. It was highly recommended to leave the controller leads full length, even though the fuse is extremely tight, I am able to carefully pack everything and close the carbon pod cover. I am also using a piece of balsa to insulate the wires from touching the motor, which can get very hot. This likely caused the loss of my 125 controller in Visalia.

After my first flight, I had noticed the default prop brake setting is OFF on the ICE controller, something I have always taken for granted on other Phoenix controllers. I went into the archaic throttle-based Yes/No beeping menu to get it set. Will be nice to get the Castle USB data onto my PC for the first time. I noticed during pre-flight one of the 2 pins securing the horizontal stabilizer was coming out! Yikes! I pushed it back in. I had never noticed this before. This probably happened at Visailia during the speed runs. The stabilizer itself is showing signs of...Continue Reading
Posted by mechmove | Jun 14, 2012 @ 12:00 AM | 2,305 Views
There is an update to this problem at the bottom.

The last couple flights of my Supra was "interesting". There was considerable DOWN pitching moment in the airplane. No matter what, the airplane wanted to descend, even if I trimmed the nose up. I couldn't figure out why. I thought it might have been sinking air. The airplane did remain controllable. The CG is set at 100mm from leading edge, which has always worked fine.

There is one thing that I was not really comfortable with in my Supra; having to fold the Futaba receiver wires inside the fuse. So I decided to run the antenna outside the fuse to get the 90 degree layout that Futaba recommends. Yes, even with a Kevlar/glass fuse.

This meant I had to I drill 2 holes in the fuse to feed the Futaba Antennae and route it outside at 90 degree angles. The receiver sits on top of the LiPo which is pushed back far inside the fuse. During the pre-flight, I insert thin plastic tubing to guide the receiver wire from the inside to the outside of the fuse, which is then routed through heat shrink taped along side the fuse at 90 degree angles. Since the antenna is not taped anywhere along the fuse, there is no tension that exerts "pulling" pressure from the receiver. Now I have the "recommended" Futaba 2.4G installation - 90 degree separation, and full length antenna wire that does not cross.

I test flew my ship immediately afterwards...no issues! It needs to be noted that there is no logic to assume...Continue Reading
Posted by mechmove | Apr 15, 2012 @ 11:55 AM | 1,985 Views
First off, my current configuration in my electric AVA and Supra has been flight tested and works fine. Futaba FASST is almost foolproof in its end-user implementation. It appears we can break many rules without problems. But that does not mean we shouldn't try to implement according to manufacturers' directions: I wanted to optimize the 90 degree separation for “best practices” in 2.4G theory while keeping the antennae in the fuse.

So attached are pics of my latest configuration that. I don't claim this to be an “answer” for anyone, just make sure to range check all your changes!
Posted by mechmove | Apr 09, 2012 @ 12:30 AM | 2,106 Views
With my AVA e, Whittier Narrows in the morning. Lots of families camped out for Easter Sunday. My flight was almost 30 minutes, launched from the south side of the Helicopter area. Lots of lift. I wanted to stay out of everyone's way, so I needed height. Since my airplane has an 11 ft wingspan, it was easy to obtain height and stay out of everyone's way. Last thing I want to do is stop anyone else from flying their airplanes/helicopters. I still felt as if I should probably attempt to fly when no one else is there, like during the week when I am off.

For landing, I ran a tight circle in front of me, and landed in front of my feet. The nose of the airplane hit a soft dirt patch, so some cleaning required.

This is the most comfortable I ever felt flying this airplane. The receiver battery was charged in the morning using my Sirius charger, and after the flight, the pack was still reading 5.65 volts! I could have stayed up longer, but my neck gets tired looking straight up for so long.

Then I went home and returned to the field in the early evening. This is the first time I ever saw the park completely packed with families. I managed to park in the Control Line area closest to the 60 freeway. This time, I flew my Supra under 13 minutes. Gusting winds made the flight hectic in addition to flying into the sun. In the beginning of the flight, the winds were coming out of the west, which would mean a crosswind landing. Then the winds turned more from the South, which is...Continue Reading
Posted by mechmove | Apr 08, 2012 @ 10:22 AM | 2,222 Views
My Renny with 1350mAH 2s, is a bit lighter. Retaining my balance at 80 mm from leading edge, required removal of a piece of lead tail weight. I also managed to replace the gear box screws, the official size is 2mm X 6, but I ended up getting 10 and dremeling them down to size. All hobby stores carry these screws. 2s also means a slow climb to altitude. This plane is now for light lift days, or sloping which is something I enjoyed tremendously

Also of interesting note, since my firewall was mounted with too much UP thrust, and the motor is angled more DOWN with a an offsetting washer, the propeller spinner barely touches the gear box shaft. What does this mean? I need to check the prop with motor on for any "wobbling", and re-mount the spinner until the wobbling stops. I initially thought the shaft was bent, but this cannot be the case. I should break and re-construct the firewall as to enable the spinner to sit on the full length of the gear box shaft, but I do not want to spend too much time with this airplane if things are flying OK.

Yesterday for the first time, I launched my AVA e with my Eagle Tree altimeter. I find this device interesting as you can see a static port on the tiny unit. I am not sure how accurate the device is, but it gave me a good idea with my in-flight altitudes. My flight time was around 18 minutes. After landing, it appears I hit a maximum altitude of 611 ft. I was pretty careful to keep motor runs close to the ground, since I am...Continue Reading
Posted by mechmove | Apr 07, 2012 @ 10:30 PM | 2,297 Views
The past week, I was able to clear up some minor issues regarding my Futaba receivers. First concern, antennae placed in the fuse prior to launch. I wanted a way to ensure the 2 antennae did not physically cross during pre-flight. I am sure the antenna in the past cris-crossed, as I jammed the wires in the Kevlar fuse. This hasn’t posed a problem yet, but the ideal installation is 90 degrees from each other. Since I prefer to keep my antenna inside the fuse, making sure they are straight and do not cross is important since 90 degrees is not possible.

So I devised a means to insert the antennae into heat shrink, and tape everything to the receiver. See photos. For the AVA, this was easy since there is so much room. I also installed my Eagle Tree Altimeter which was previously in my Renny Electric.

The Supra electrical system was extremely cramped and had me worried that wires might frey during pre-flight causing issues in-flight. So I entertained everything from moving the receiver into the center panel (I couldn’t get myself to cut into this work of art!) to pushing the receiver back as far as possible and routing the antenna outside the carbon.

But I found a much better way!

First issue was the 617 receiver and the amount of space required AFTER the all the wires are plugged in! The 617 receiver is tiny, but the vertical mounting of the connectors make this less than ideal in a tight fuse. So the first step for me was to replace it with the F6008 HS...Continue Reading
Posted by mechmove | Mar 19, 2012 @ 06:39 PM | 2,082 Views
This morning, I had another day off, and went to Pasadena to fly my AVA and Supra electric. It was cold, in the 50s' F when I arrived. During my Supra setup, I realized I had left my nose cone screw at home! So I flew my AVA first. Despite the cold weather, there were considerable thermals to be found!

Then I drove home to pick up the lost screw, found it on my driveway!

I setup my Supra again, and checked that the new battery I purchased from SoaringUSA (TP 3 cell, 3.3A 65C) would provide maximum continuous thrust prior to launch. It did The climb out was fierce; a 5.75 lb vertical rocket ship! All I need to do is add a smoke trailer, and someone will think its a mini rocket ship or a tiny JATO system.

I had a short 11 minute flight, but it was stable and predicable. When it wasn't climbing like a bat out of hell, the airplane is flying slow and graceful. I brought the flaps and spoilers down on final (crow), and didn't slow down at all. So there were no surprises It was a long and smooth landing.

Now thinking about reducing weight so I have something that thermals better.
Posted by mechmove | Mar 18, 2012 @ 06:42 PM | 2,161 Views
After the sun came out, I headed out to Pasadena, and a few guys had the same idea as me I was about to re-maiden my Supra when I had an unexpected problem; at full throttle, the propeller stopped spinning immediately after launch!

Luckily, it was very windy, and since I was careful to launch upwind, the airplane nosed up at 10 ft, then as it came down, I managed to grab the tail boom, preventing another accident! This happened as there was a huge gust of wind, so it all felt like slow motion. Wow, today was my lucky day.

Another lesson to make sure to do an "Engine Run-up" prior to launch, and I would have seen this problem for sure.

What things can we carry over from a PPL!
Posted by mechmove | Mar 18, 2012 @ 12:25 PM | 2,410 Views
This is a summary from Thursday to today.

Please note there are some repair tips from West Systems regarding composite wings that that I am passing on for the benefit of others, though I decided not to go this route.

This morning, I finished sanding my Supra wing. Pictures of the entire project and finished surfaces at the bottom. Please keep in mind, this is my first composite repair, so this is more documentation than a “how to”. Though the new surfaces are not 100% smooth, it is close enough for me to start painting, though that is low priority. I disassembled the entire airplane from tip to tail over the last few days, and confirmed it is ready to fly!

Last night, I finished soldering the mini Futaba connectors to the wing and tail servos in preparation to receive the 616 FASST receiver that is back-ordered. Things to do when the receiver comes, mount the battery pack and re-check the CG 62mm from leading edge. My radio already has the basic settings, just need to fine tune at the field. Will be nice to finally have all my planes airworthy and on 2.4g FASST, which has proven it self to me time and time again. What an improvement from the 72 mhz days!

Last Thursday, I had a day off again! Early morning, I started repairs on my Supra Wing. I contacted West Systems the other day about the best way to make my repair; for the benefit of others, and my future reference here is a copy of the transaction:

Me: “I am trying to repair my radio control glider's...Continue Reading
Posted by mechmove | Mar 12, 2012 @ 06:05 PM | 2,185 Views
Today, my day off, I managed to get a lot of things done. Of course, I had to sneak in a flight as well. Again, I went out to Fish Canyon to give my Electric AVA a spin, its' first flight ever at Fish Canyon.

Launch time was around 2:30pm, light wind gusts and great thermals, as I would have expected. The climb is fast and steady. At one point, I got into a boomer and decided to lose altitude since the plane started getting small and faint. Listening to the wings “howl” makes me think how clean this polyhedral ship actually is, and with the added weight, she picks up considerable speed as compared to the glider version.

After 11 minutes, I decide to commit to a landing. I had a hard time positioning for the large field, and after several go arounds, was able to execute a soft field landing on the electric “padded” runway.

Since there is no other way to slow the glider down minus flaps or speed brake, and I didn't want my plane to go into the brush, I opted to circle over the glider landing area, and came in on the electric side.

Still, landing was no easy feat since my AVA weighs a lot more than the glider version, therefore requires a higher landing speed. It even appeared to me that during downwind gusts the AVA picks up lift due to the shape of the wings. Maybe I am wrong, but the AVA should have been categorized as a boat, not an airplane.

In addition, the Kevlar fuse is not something you want to “dork” in, not to mention the...Continue Reading
Posted by mechmove | Mar 12, 2012 @ 02:13 AM | 3,023 Views
After talking with the SWSA guys at the field this morning during contest, I returned to Fish Canyon alone around 5pm to fly my Supra Electric. I used to fly my Renny Electric at Fish Canyon back in 2008. So there was considerable reservation for me to fly again with an airplane which is a lot more expensive, and flies a lot faster in an area that has a limited landing zone. I had a serious case of jitters to say the least, and as it would turn out, it was well justified!

I launched full throttle, and noticed the ship was climbing out with pitch-up tendency. I didn't know if this was related to CG, too much UP elevator position, flying upwind, or incorrect motor thrust angle. As I leveled out, there was still some pitching, so I trimmed down a bit. After a while, the airplane flew fine. I probably need to dial in some down elevator on launch.

I experimented with camber and reflex, which seemed to work pretty well, though I could probably dial in more travel. The thermals were very powerful at times. Then I tested the landing configuration at altitude, and that seemed to work, but the real test was whether or not I would make the field.

Then after a 17 minute flight, I was ready to attempt a landing. Since my Supra does not have full 90 degree flap extension, I was trying to lose altitude and speed before committing to final. As I was circling downwind on final to lose altitude, (IN FRONT OF THE HUGE TREES), one wingtip hit a tree, and the ship came down in the...Continue Reading
Posted by mechmove | Mar 11, 2012 @ 10:51 AM | 2,711 Views
More than a few times, I had experienced the spinner coming off my Supra Electric on launch. I was told by one of the friendly staff at Soaring USA to flatten one of the screws holding the spinner, then barely tighten it. Tighten the other side all the way, then come back to the flatted side for the final twist. I found I method of “flattening” one side of the screw by leaving it on the hex wrench, securing it on a vice grip, then “touching” it with a dremmel with grinding stone attachment.

So to test the change, I went out to Paramount Ranch in Agoura Hills yesterday, a 1 hour drive from my location. Yesterday was stellar for thermal flying, but was my first time in the canyon. I was told the winds can be unpredictable and unstable, perfect conditions for finding lift. My intention was actually to fly, but as I walked out into the field, I immediately thought about how I would attempt a soft field landing without damage to the gel coat or damaging my folded carbon prop on touchdown by hitting a rock.

So instead of flying, I decided to power up the motor to make sure the spinner stayed on.. it did. The amount of thrust from the motor at full power indicates plenty of takeoff power, but landing an expensive glider on that terrain poses a challenge.

I am giving thought to some form of landing reinforcement for the fuse and wing tips, like clear packing tape and replaceable masking tape, to be replaced after each landing or as it wears.

I'll see how well that works.

But then the issue of the propeller.... if there was a way to program the brake to stop and fold the blades in a pre determined position...my Castle 125 controller does not mention this as a possibility.

I am also renewing my membership with Silent Wings Soaring Association so I can fly at Fish Canyon, where there is AMA coverage and a friendly group glider pilots.
Posted by mechmove | Mar 08, 2012 @ 10:23 PM | 3,029 Views
Today on my day off, managed a 15 minute flight on my AVA e! Was wonderful weather for thermal flying.

Then I visited Soaring USA to buy 2 4-cell NiMH battery packs for my Garnett DLG, crashed in July 2008. The repair started last week. I managed to drill out the stuck carbon wing joiner from one of my wings, then proceed to replace it with a 7/32 X .014” aluminum tube from a hobby store. This was easier than I had first thought. I had to gently bend and reshape the tube with pliers to make the wings fit securely. Since alumimum can bend, I filled the small tube with a mixture of epoxy and microballons for added strength.

Since the bottom wing joiner was missing as well, I simply used a nail of same diameter and dremeled to the correct length. We will see how well my repair holds up.

I was previously flying this ship on 72 Mhz. I wanted to get a Futaba receiver into the fuse, but the 617 I am using in my Supra / AVA does not fit into such a small fuse! So I ordered the 6-channel 616 FASST with single antenna. The range is supposedly 1000 FT.
Posted by mechmove | Mar 08, 2012 @ 09:45 PM | 2,815 Views
I managed to jump start my Honda using my 3.3aH NeuEnergy LiPo. At 60c, it supplied ample starting power for my car!
Posted by mechmove | Mar 08, 2012 @ 09:44 PM | 2,776 Views
A few days ago, I powered up the radio, and looked closely at the Supra program with the airplane ready to fly without motor. One thing I had discovered the Speed and Start switch was enabled with down and up elevator respectively. I immediately disabled that switch since I want ease of use, at least for now. Launching with such a powerful motor does not require any particular wing or elevator setting.

So my radio program is simple. I have full wing Camber and Reflex on the left rotary. The landing switch is on bottom right side, which overrides Camber / Reflex in favor Crow; flaps down, outboards up, and elevator (nose down), to be applied with left rotary. So the radio is as simple as it can get, only 1 switch for Landing, and another switch for motor cutoff.

The theory is to launch with all surfaces neutral, then when finding a thermal apply full wing Camber, and when sink comes, go into Reflex to increase speed and fly out. Of course, the motor is always there. Then on final, throw the landing switch and apply crow with the rotary.

I also noticed an outer edge of the carbon wing pod was slightly damaged, but not by much. This should be insignificant during flight.

My Supra is ready to fly!
Posted by mechmove | Mar 08, 2012 @ 09:43 PM | 2,670 Views
Back in 2010, I had mounted a flip camera in my car to record “video diaries” for personal use. Fortunately, I made pre / post accident videos about my Supra Electric. If it weren't for these videos, I wouldn't have the background needed to investigate a major flaw in the radio program for my Supra.

As it turns out, my elevator was compensated in the UP direction for landing mode. I remember the wild pitching moment and then the nose-in crash. Without regard to “sound” aerodynamic theory. I thought it was the new polyhedral wing joiners. It wasn't. My notes and recollection at the time I was trying to re-assign the landing configuration to the left index finger rotary switch on my Futaba. Prior to this, landing configuration was set to a binary ON/OFF switch without the possibility of variable flaps. Since I had made 2 changes at the same time, either one could have been cause for a crash.

The Theory : Elevator is supposed to compensate nose down when flaps are deployed which would have countered the sudden lift under the wings (“bellowing pitch UP'). In my post-accident video, I had mentioned the possibility of having programmed the Landing elevator in the wrong direction, and I was completely aware which direction it should have been at that time.

I didn't actually check until now, 1 ˝ years later. I cannot believe I made such a fatal programming mistake.

So how could this happen? I suspect my stabilizer was not installed when I changed the radio program...Continue Reading
Posted by mechmove | Feb 23, 2012 @ 11:02 PM | 2,422 Views
After reviewing my RC diary, it turns out the exact date of my Supra crash was on July 18th, 2010. Since then, the 4-cell 1,600 mAH battery has been untouched in the broken fuse. Over the last few days, I put the battery on the charger and ran a few cycles. I confirmed all cells are still good, and a charge / discharge of 1,300+ mAH means this battery is in pretty good shape for the near future.

As a side note, although I still believe the cause of the crash was changing the wing joiners for max polyhedral, my notes indicate I had changed the radio program for landing as well, and the elevator setting might have been changed.

This could mean I will have the same problem even when using the original wing joiners...I'll have to be extra careful and try this at altitude before committing to land!
Posted by mechmove | Feb 20, 2012 @ 04:16 PM | 2,287 Views
This morning, I re-mounted the motor in the nose cone. Due to having to repair the firewall, there were problems with the motor thrust angle. But with small washers, some CA, and trial and error re-positioning, I got it right.

I put the model together, confirmed CG around 100mm from the leading edge, then carefully attached the Deans to the Lipo. Standing in back of the model, and with the model secure, I engaged the motor safety switch. At first a gave a couple bursts at low RPM turns. Then a few more motor bursts at slightly higher throttle. That unbelievable high tech spinning sound. I also noticed the entire nose cone warps at the point of attachment due to the enormous torque that is present, even at relatively low RPMs. This must also put a lot of torque where I made the repair. This will need frequent checking.

I disconnected the batteries and held the model up in the air, prop facing me...... then the same feeling came back, a very sleek and heavy glider that could do lots of damage if it impacts anything that gets in its way. I have to admit, this model scares me. I got into modeling to have fun, but all the warnings about RC airplanes not being toys is especially true with this glider. This airplane didn't come with any warning or instructions. It is just obvious. All up weight 91 ounces. The weight alone makes this airplane dangerous at any speed, and with straight wing joiners, it picks up lots of speed fast.

I feel comfortable knowing electric Supra is airworthy again. But I am not comfortable flying it anywhere. Fields large enough for this airplane are for general public use. The AMA fields are too small. I'll have to reserve this airplane for fields that are large and safe enough, which might require a long drive making this a special use airplane!
Posted by mechmove | Feb 18, 2012 @ 09:59 PM | 2,594 Views
Why am I doing this?

Read the following for background:

http://www.rcgroups.com/forums/showthread.php?t=1593280

The firewall repair was straightforward and easy, 30 minute epoxy and a clamp with Saran wrap to isolate the components that apply pressure. I had made an impromptu “mold” using a cardboard box for the outside of the firewall since the clamp pressure went up against the rim and not the firewall itself, resulting in a large space that epoxy could crawl into. After the epoxy set, I noticed there was still some gaps where the broken portion of the firewall didn't sit flush, so I added some epoxy and microballons as filler.

Now the fuse. Since I am in no hurry, I looked into ways of making the repair from the inside. The reason being there could be cracks underneath the gel coat, which may not make direct contact with the epoxy/fiberglass if repaired from the outside. So my thinking was covering as much Kevlar from the inside would guarantee reinforcement in all cracked areas. But the problem of glassing inside a fuselage!

The secret was my old can of 3M 377 spray! I had bought this spray in 2001 to build my Zaggy Foamie with Speed 400 can motor!

First thing was to wrap the fuse in Saran and masking tape to prevent any epoxy leaks from seeping outside as fiberglass and epoxy was applied from the inside.

Then the hardest part, taking fair-sized rectangular pieces of heavy-grade fiberglass cloth, spraying on one side, then with long wood sticks...Continue Reading