The Cat-Proof Castle, Sbach Mod

I am building the second Sbach 70, and to keep the cats off of it (they like chewing them...), I built a castle around it. It worked!

One of the things I learned with the first one was that the metal used for the elevators (one has servo control, transfers the movement to the other with a U-wire). I took the wire and soldered a heavier steel rod to it as an anti-torque bar. Works great!

That'll do...

It was a great day with some positive excitement for a change!

Kenny got up early and had Jason maiden his newly built 35cc gas MX2, then took it 

Kenny and his MX2

Kenny and Aidan

Ray was cutting the field, took a break to let us fly. MCRCC is easily the best field I have ever flown at.

Spun up the Trex 600 to check balance and tracking. Wanted to hover but Ray got back to business.

The truly exciting part of the day was the 3-4 flights Aidan and I put on his Alpha 450. At one point he was coming across the field towards us when he went inverted in a gust at about 15 feet. I took control, recognized I was not going to be able to roll upright without hitting the ground (its a trainer with a dihedral, not an aerobat). I got it under control flying at a 45 degree angle inverted towards us... gained altitude as it climbed over the pits heading for the trees, turned left and found enough altitude to roll back upright, flew back over the field at altitude and gave him back the plane. I was pretty impressed that I actually let go of the trainer button to gain control when the gust caught it, my whole body clenched up. I rocked it, totally!

The Second Sbach 70 arrived today...

With the wrong stickers. I think its a manufacturing thing. Both of the kits I received had the white Sbach 342 sticker that clearly doesn't belong on a white wing. Last time I wrote General Hobby and they said they sent the right stickers, even sent me a tracking number (9400111899560878772259) that was never actually mailed. I wrote them after seeing the same problem and asked them to send them to me... lets see what happens.

I wonder if I have the skills to create a background in black cote that I could put the sticker on?

It's Time...

EXI45 Sport Flight Ready. Again.

This morning I finished the last couple of steps to rebuild the EXI 450 Sport that underwent a pretzel event last week.  I ran her up without blades, no vibration, put the balanced tail feathers and ran her up, no vibration, balanced and installed the main blades, checked the pitch and ran her up, no major vibration. Next step will be to lift her off and see were the tail goes. I reviewed the Alighn 780 gyro setup and reset the endpoints, gain at 65% to start.

I made a few programming changes that I think will have a significant impact. I removed my looney "soft" mode of 80% pitch limits in Idle2 (WTF...) as I realized that this changed the slope of the pitch curve relative to the full 100% pitch range curve in Idle3. This was why I got a little skip switching between idle-ups. Stupid. I kept the novel Idle1 of zero pitch across the board. Now there is no difference between Idle 2 and 3.

I also decided to go back to DR of 50-75-100, and 25% expo across the board. I need the finer expo for control. We'll see how that goes.

Next step, test crashing, I mean, um, test flying.

UPDATE: Spun it up and there is some wacky vibration, fine occasional coarse, low amplitude high velocity, coming from the tail assembly when the blade hub is put on (with or without  blades). Happens at certain rpm and pitch. I changed the bearings, blades, tightened up, still there. Its pretty impressive and loosened all the bolts despite liberal locktite. I can't fix it. There is a hint of play in the bearing hub and the tail shaft hence has a touch of play. I decided to just order a Tarot tail assembly...

EXI 450 Rebuild, Billionth Time

So...

The other day I was flying the EXI450 Sport, trying to isolate some severe vibrations that were causing a tail wag, making the gyro gain very impossible to nail down, while also trying to figure out what rates and expo I like, when the tail belt snapped and she instantly pretzeled four feet off the ground onto the pavement. It was one big ball. One main blade sailed over my head (a good 15 feet), and the tail boom snapped off from the torque. The gyro took a blade hit as it flew off its perch and has a nice dent in the case, and the tail blades became shrapnel. The solid steel main rotor shaft bent at 45 degrees, and even the solid block aluminum rotor head got a 2-3 degree tilt in it (can't see it, but when I replaced the shaft there was a significant wobble in the rotor head not present with shaft alone). The tail shaft also got tweaked. Needless to say, the fly bar was a swirly. None of the servos failed, however, all passing inspection and motion testing. There is a tremendous amoun of energy in these helis, and it all instantly traded places.

I was annoyed and damned if once again I didn't fail to take a pic.

Ordered a new tail boom (of course I have hundreds in storage...) and a new Align Sport rotor head block. I didn't expect them so soon but they arrived today! I took apart the entire swash cage and rebuilt it with the new rotor head, cleaning and lubing up everything that moved. New flybar installed, a few mm shorter than the ruined one. While I was waiting for these parts I replaced the main shaft, the stripped main gear. I had also rebuilt the tail assembly. I didn't realize I had built it backwards, even after I installed the tail boom and it had to go in upside down (I even cut a new detente groove in the forward end). I have used Tarot booms which required an upside down installation on an Align machine, and I thought maybe the original tail housing on the frame was a Tarot, so didn't think too much of it. Today after I had reinstalled the tail housing, boom and tail rotor assembly, I realized I forgot to put the control rod guides and the servo clamps on the boom first ... (I was way distracted with an upcoming business trip). I took everything apart again, slid the tail boom pieces on there and rebuilt it. When I went to put the tail guard/vert stabilizer on, I realized I had assembled the tail assembly backwards! That's why the slot was on the wrong side and I installed the boom upside down, dammit. So I had to dis-assemble the tail assembly and re-assmble it properly, pulling it off the boom and drilling the rear pin detente hole on the "wrong" side, and reassembling it. In the end I basically installed the tail boom upside down and had to McGyver the forward and aft tail boom detentea. What a frickin' waste of time, but I didn't want to waste the tail boom. This is so not like me...

It all works fine. Without blades there is very litte fine vibration. I re-installed the tail servo and control rod, but haven't set them in place. I'll do that when I come back. Installed the brace supports and called it a night.

Took this photo during a break, before putting the tail boom braces back on. Next time, balance the new main blades and install them, and the tail blades, set up the tail and fix the tail servo in place, then see if all this cleaning and replacing fixed the vibration issues! This heli has been rebuilt so many times....

 

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Another death in the family...

It started out well. I went out solo this morning, first on the field and had it all to myself. Virtually no winds, occasionally a brisk crosswind gust, but never threatening. A quiet Sunday morning at MCRCC. I got out there around 10am, ready to go.

I took Aidan's Alpha 450 up, and ran it through its paces. She flew great with her extra nose weight, and I practiced short and cross wind landings as well as work on orientation. She is tight in control, predictable and rugged, everything you want in a trainer. She's a keeper, and I am glad Aidan and I each have one to keep our basic flight skills honed, and to share this hobby with others. I flew a couple of packs, but then that clicking noise came back when she tipped over her feet in the thick grass despite bigger tires. The rotor was on the move again. I tweaked her up and she flew fine. After 4 packs I put her away for the day. That'll do girl, that'll do.

 

When I got her home I took the prop off and realized there are cut out flat spots on the motor shaft, so I worked to get the lock screw to set in there with some locktite and gorilla snugged it into place. Hope that's the end of it.

 

After that I took the Pulse up and ran her through some aerobatics, getting mentally in place to follow up those aerobatics on the Sbach. She is so well built and tuned, not a vibration anywhere. her motor ran true and silent. I flew her for one pack, sweet, high powered high altitude work, a couple of touch and goes in the northerly crosswind, and decided I was ready to take the Sbach up.

 

The Sbach flew like a dream... Sweet smooth effortless takeoff, into some high altitude, high speed, high G, high torque aerobatics. I put her through the wringer. I noticed a final set of loops and Cuban 8's that were less round, a little uncommanded roll as she came around. I swung her hard into a final loop to pull out into final from the south. She took off skyward like the rocket she is, a bit of un commanded roll, I pulled her back into a loop, and realized I wasn't flying her anymore. I tried to correct, no repsonse, then zeroed the controls, nothing. She waffled out of the top of the loop in a slow shuddering spin, powered her off and called out that I had no control. She was high as she came down, twisting, screaming, and slammed into the ground nose first. She hit so hard she bounced up scattering pieces all over, a wing cast off across the runway, and came to a rest in a crumpled heap about 6 feet away from the impact site. No chute, no fire... The pilot was surely dead...

 

The tan colored crater in the right foreground is the initial impact site, a hole about 7-8 inches deep. This was my walk-up to the crash site at the south end of our runway. Dick Clark came out to post-crash with me. The electronics were still live and everything worked. None of the servos were apparently damaged, all the linkages were in place. but we noticed that the CA hinges on the right aileron and elevator were separated from the aircraft. There was no external damage to the wings or the elevators otherwise (the wing that came of suffered some internal damage where the wing tube broke). The hinges pulled clean. Despite my CA work there looked to be no glue on them at all. We suspect that the hinges were weakened by the poor glue work (I really tried hard to get them to set in.., recall I had to redo the rudder hinges on the field on her maiden day), and worked loose by the aerobatic maneuvers, evidenced in flight by the dirty loops and the sudden loss of control during a maneuver at altitude with intact electronics. The rudder wires had also stretched during those maneuvers. I check them before each flight and they had been snug, but now visibly slightly sagged. None of the wire linkages separated and they showed no wear. The freed elevator did not move with the main elevator but slightly.

 

 

 

Curiously, neither the prop, motor, electronics, landing gear nor the wings and tail, for the most part, had any significant damage. The fuse was powdered, but that was it.

When I got home a visibly shocked Aidan helped me recover the electronics. I tested the motor and it worked fine. I had to work the prop screw loose and then cut the adapter rotor off to get the prop off. The impact smashed the aluminum prop adapter shaft and the steel screw together and totally smashed the screw so that it locked and stripped. The spinner was oddly totally fine, albeit muddied. Further evidence of the altitude and energy of the crash. Still shocking how little the rest of the plane suffered.

 

I wasn't sure what I would do... I recovered all the electronics and they all seem to function well. I ordered a replacement SK3-5055 prop adapter, but am not sure I will replace the plane right now. Surely I will.

UPDATE: I was looking at the HobbyKing version, but after an hour dicking around with their website issues, I learned it would cost an additional $73 to ship their version from the USA warehouse. Great price for the plane, but the shipping killed. Since the General Hobby Skyline version was a good plane really, and on sale for two more days with $25 shipping, still way under the HobbyKing cost, I opted to go ahead and replace it from General Hobby. Since I was leery of the supplied hinges and they failed, I have also ordered nylon and metal hinges from Hobbylinc for cheap. The new plane will have reliable hinges.

When. I come back from a business trip this week all the parts and the plane should be here. Should be a quick build.

 

Posted with Blogsy