Repairing "Kenny's" MX2

Its mine now...

So Kenny had this Goldwing MX2 that is advertised as capable of being powered by the DLE 30cc gas engine. It can be, but it tore up the wing, around the wing tube, likely due to the flight forces the powerful gas motor put on it. He trashed the internals of the right wing. Since he could replace it, and was moving on from the plane anyway, he said it was mine if I wanted to fix the wing.

I couldn't get great pictures of the damage, but the ribs were broken and cracked for the length of the wing tube. The distal wing was fine. I opened up the bottom and took to it. I shored up the most broken parts knowing they took the most wing load. I wasn't going for pretty. Someone, unbeknownst to Kenny, had made similar repairs to cracks with glue, but no wood. I wanted this thing robust, with a nod to adding too much weight.

Looks pretty...

Big surface cracks with failed and blown out ribs underneath.

Small failures...

Major failures with blow out.

Hard to see but every rib cracked and some with blowouts.

One example of a blown out rib, cleaned up.

Laid popsicle wood down with one splice. It was the same width as the original wood.

Lots of CA. Blue tape keeps CA off cote.

Another set of repairs. Every black dot is where I stuck the pencil used to place the piece of wood inside the balls sheeted parts of the wing. Two major ribs here near the wing root were blown out. You can't see where I buttressed the ribs along the chord of the wing inside. Also, the thick (0.8mm) plywood that makes up that last rib with the screw it it at the wing root was also delaminating (you can see the crack at the "top" of the rib in the pic (its actually the bottom of the wing at about 11 o'clock. At 1 o'clock you can see where the sheeting popped out from behind the rib. Fixed that too.

A shot of that major rib repair. I ran that popsicle stick rib as above then overlaid a 4mm square rod of balsa along both sides of the original rib, running under the edge of the popsicle stick (which runs along the actual top of the wing). This is where the major loading occurred. That round hole is the end of the wing tube, so this is where its cantilever forces end and the wing can flex. Will run one piece of wood in an X between these two ribs to support against that flex.

I added some epoxy to the major joints, but the joints and supports I added are CA's into place. Will see if I can get some of this green cote at the LHS tomorrow. Final pics to follow. 

I just bought Kenny's 30cc Sbach from him, so it will be awhile before I get the electronics for the MX2 to rebuild it as an electric, but she will be awesome. I am pretty sure she will be Aidan's second plane!

A nice simple day

Memorial Day 2014

Met up with Kenny at MCRCC, and the crowd thickened as the day went on. Jason was there helping tune up engines, and got both of Kenny's running. Finally his 1/4 scale Cub running well, he enjoyed flying it in the moderate winds. It ran smooth as silk. Still working on his Sbach engine when I left.

Kenny's Cub

Dickie Ober brought a couple of tri-copters. He said they flew like hybrid airplane-helicopters, and then he proved it! This one was a hoot as he flipped it, rolled and looped it! He made it look easy. Then, despite the winds he took up an Align 130 micro  CCPM helicopter and put it through a 3D routine. Man got skilz!

I flew Aidan's Alpha 450 checking out the new nose "oleo" linked gear I had put on it, then flew the Pulse. Lots of wind made for some fun. I had also brought the Sbach to maiden, but being that I am not 100% getting over a cold, and the unpredictable gusts, I opted to keep it in the car. I also managed to hover the EXI 450 Sport. It still has a particularly violent shake at a certain RPM during spin up, and somehow the main shaft is slightly off center, somehow bent.  I think I will just leave it be and use the parts in the new frame I have coming.

All in all, a nice, simple day.

Skyline/Goldwing Sbach 70 60" #2 Flight Ready

This morning I finished the setup on the second Skyline/Goldwing Sbach 70 60". You may recall the first one committed seppuku on only its 4th or 5th flight. I didn't blog this build as it went very much like the first one with a couple minor changes. One is that I made the rudder wires tighter.  I also used Du-Bro nylon hinge-and-pin hinges on the control surfaces with epoxy (the wide ones) instead of the flat fiber ones with CA.

She has the same power system and electronics. I have a 17x8 prop on her (turns out I had a 17x7 on before). I have ordered a 3 blade 16x8 EMP prop and a Du-Bro plastic 3 blade spinner. These don't come in 2-1/4', so had to get a 2". On a quick power test this morning I got a peak of around 1540 watts. Curious how the 3 blade will perform.

Common to both is that the wrong decals are included in the kit. Instead of the stickers for the red-white-black one, they come with the set common to the other colors. The white letters obviously don't show up on the white wings. General Hobby says they are sending the right ones, but last time even giving me a tracking number didn't get them in the mail so I am not holding my breath. The only one missing, really, is the large Sbach 342 that should be on the top left wing.

All in all, she setup. CG'd and looks identical to the first one. Looking forward to the maiden flight!

Don't Give Up!

I had tossed the EXI 450 Sport into the parts bin en mass after getting fed up with trying to solve the vibration problem. Last time I took it to the field it freaked itself out just sitting on the ground as it vibrated itself into havoc. I had cleaned up all the vibrations, but once the tail blades went on it vibrated finely and ended up creating gyro oscillations which lead to odd rudder inputs from the gyro.  I just could not solve the problem. So I hated on the heli and put it in the bin.

I also can't stand an unsolved problem, so today, after a couple of days of walking past the bin with agita every time I saw the heli,  I pulled it out and worked on isolating the gyro. Nothing really worked well. And then I remembered seeing a drawing on an Align gyro manual that showed various possible positions for the gyro, and I remember one in front of the main shaft rather than the traditional aft of the main shaft. This would move the gyro away from the finely vibrating boom and tail. I also changed the tail blades (weight balanced against one another) and new main blades, I changed the main and feathering shafts, and improved smoothness of movement in the tail assembly. This this is as clean vibration wise as I can possibly make it.

So, in main blades off spin ups the rudder servo was still and not being affected by vibration! I had to modify the canopy to allow the gyro forward. Tomorrow I will try hovering and possibly flying it!

If this doesn't work its back in the parts bin!

UPDATE: POS... into the parts bin. Still shaking itself apart. No idea why, done trying to find out. I have 3 other 450's to spend my time on.

UPDATE-UPDATE: So... I got to thinking, maybe its the Align 780 gyro? I threw an Assan GA250 gyro I had in the box on her and spun her up. She still has a very high freq vibration, but the gyro held and she didn't wag, nor did she shake herself apart! I plan to see what happens at the field on Memorial Day. I did order a $30 Hobby King 450 Pro V2 chassis to replace her though.

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?