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Old 01-13-2017, 03:00 PM   #41 (permalink)
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https://hobbyking.com/en_us/aluminum...x-550-600.html

Maybe?
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Old 01-13-2017, 03:14 PM   #42 (permalink)
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It says "out of stock", and that does not mean just backordered, I believe...
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Old 01-13-2017, 10:26 PM   #43 (permalink)
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I got the elevator servo position corrected by cutting the elevator servo mount in half. The ball on the servo arm is still a few millimeters off center, but I'm not worried about that.The resulting angle is certainly no longer large enough that I have to worry about the linkage popping off, and since it's an axial offset it should not matter in terms of servo travel - I think.

I hope I can get the swash low enough that the antirotation bracket can be cut down to stay inside the doghouse, but that will have to wait until I get that new head. The swash driver may not allow lowering the swash as much as I would like to, and by its design there is no way to extend it. According to the manual the blade linkages are 56mm long, and the scale rotor position happens to be about 56mm above the doghouse as well. This means that I have to extend those linkages by 10-15mm to keep the swash inside the doghouse, which may be pushing it for the swash driver.
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Old 01-15-2017, 10:54 AM   #44 (permalink)
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Got the new 850kV motor installed today. I still need a pinion; planning on either 16t or 17t with my stock 170t main gear. Assuming 90 percent efficiency and a 90 percent throttle setting, that should give me either 1440 or 1530rpm on 6s. I'm planning on using symmetrical blades.
Does this sound right to you?
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Old 01-15-2017, 12:33 PM   #45 (permalink)
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It should work just fine.

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Old 01-15-2017, 02:09 PM   #46 (permalink)
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By the way, here's the subject. Let's see how close I can get with this project...
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Old 01-15-2017, 06:39 PM   #47 (permalink)
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I made those blades at the rear of the skids, using some plastic material from the lid of a food container. I got this idea from Nelson's build log - thanks!
The screws are obviously too long, but this was all I had at the moment.
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Old 01-16-2017, 10:36 AM   #48 (permalink)
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While I'm waiting for parts I spent some more time on the skids. I made the pilot's step from 1mm ply wood; still working on the long step on the left side.
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Old 01-17-2017, 07:17 PM   #49 (permalink)
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My Align 3-blade head arrived today, and it's an almost perfect fit!
The collar sits high enough on the supplied shaft that I was able to slip the removable collar from my stock main shaft in-between it and the upper bearing block, with a millimeter or two to spare. The rotor plane ends up 50mm above the top of the doghouse; the exact scale position according to drawings would be 56mm. I can live with that little difference.
Now I have to get the correct length linkage rods. The stock pitch linkages are 56mm long, so those would barely reach into the doghouse, forcing me to increase the opening to make room for the servo linkages. Instead I will use somewhat longer linkages to lower the swash some more. An additional 10mm should be possible, so I would have 16mm between the swash at zero pitch and the doghouse. I'll first assemble the head and swash and go from there.
The head comes with the hard, black dampers. I'm planning to replace them with gray ones to make the head more suitable for low head speeds.
The hole in the center of the head has an M3 thread. Now I need to find the right size head button to make it look more scale. Based on those 3-way drawings it seems the scale size for that button is about 7cm. That seems huge! Can that be correct???
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Old 01-17-2017, 07:21 PM   #50 (permalink)
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The plastic tail unit also arrived today. Since it has that little peg that fits into the hole on the tail boom it won't need much of a clamping force to keep it in place, so using a hose clamp should be perfectly fine.
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Old 01-17-2017, 08:46 PM   #51 (permalink)
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It seems my victory lap regarding the plastic tail unit was a little premature. For whatever reason the pulley on the tail rotor shaft seems to be a millimeter or two too wide, so the two halves do not clamp together properly. If I force it until the gap more or less disappears I can't even turn the shaft anymore! How can that be???
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Old 01-18-2017, 08:03 PM   #52 (permalink)
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Some progress on the tail:
My old tail shaft fits perfectly, without that 1mm gap between the two halves. For whatever reason the pulley on the new shaft is a millimeter wider than on the old one, so the new shaft won't fit in the old unit either. I only got the new shaft to have a spare in case I ever need one, because those belt units won't be around forever. Well, could have saved that money...
Now I have to find a solution to attach the tail control arm to the new unit. It looks like the plastic unit uses a self-tapping screw for that purpose, while my old metal unit is threaded. But it's getting there...

Edit:
Found the part number for the tail control arm, and the part on eBay. Ordered...
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Old 01-20-2017, 07:56 PM   #53 (permalink)
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Small setback:
Those beautiful looking stock turnbuckles that came with the head aren't actually turnbuckles, but both ends have a right-handed M3 thread. Since I need longer linkages to keep my swash inside the doghouse I was planning on using actual M3 turnbuckles from Lunsford Racing, but I don't think I should re-use those links on the left-handed end of the turnbuckles.
The linkage rods for the 2-blade 550X are apparently real turnbuckles, unless the description is wrong:
https://www.helidirect.com/align-t-r...e-rod-set.html
It seems I have to get a set of those, just for the plastic links, plus those longer turnbuckles I mentioned before. So, 16 bucks plus shipping for a few tiny plastic parts...
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Old 01-20-2017, 08:57 PM   #54 (permalink)
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Quote:
Originally Posted by getsuyoubi View Post
Small setback:
Those beautiful looking stock turnbuckles that came with the head aren't actually turnbuckles, but both ends have a right-handed M3 thread. Since I need longer linkages to keep my swash inside the doghouse I was planning on using actual M3 turnbuckles from Lunsford Racing, but I don't think I should re-use those links on the left-handed end of the turnbuckles.
The linkage rods for the 2-blade 550X are apparently real turnbuckles, unless the description is wrong:
https://www.helidirect.com/align-t-r...e-rod-set.html
It seems I have to get a set of those, just for the plastic links, plus those longer turnbuckles I mentioned before. So, 16 bucks plus shipping for a few tiny plastic parts...
Must you use turnbuckles? Why not plain link rods? Hopefully there is a stock length in the various 700/800 parts that will work?
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Old 01-20-2017, 09:09 PM   #55 (permalink)
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Turnbuckles are certainly nicer for blade tracking, since one is not limited to making full turns on either ball link.
I just found the set of "turnbuckles" for the 3-blade head at Amain, and it's 11 dollars. I decided to bite the bullet and order it...
Tomorrow I'll level the swash and determine the correct length of the turnbuckles. I'm pretty sure the head geometry is the same as for my 2-blade head, so I can determine the maximum pitch and collective swash travel I need by just using the settings stored in the BeastX, and without actually linking the blade grips to the swash. With the servo linkages I have installed now (32mm rods instead of the stock 39.5mm) the swash ends up about 15mm inside the doghouse at zero pitch. I hope that's low enough to keep the swash inside even at maximum travel, because I don't think I can lower it any further because of the swash driver.
Other than that, his head is really nice. The closest size I have found in terms of a head button is the Century 55mm one at 16 bucks. If I can't find anything slightly larger I'll go with that one. It'll certainly look more scale than no head button at all...
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Old 01-21-2017, 11:18 AM   #56 (permalink)
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This is the geometry I get now with those 32mm linkage rods. The pictures show (left to right) zero pitch, full pitch (should be about 9 degrees), full pitch plus full (~8 degrees) cyclic, and some (should be about 2 degrees) negative pitch with full cyclic.
The linkage rods could be about 3-4mm longer without sticking out the doghouse at extreme servo angles. That would also help the swash driver somewhat.
In the last picture (negative collective at full pitch) there is still a tiny gap between the swash driver and the swash itself, which means it's not binding and won't pop off due to binding, but this looks a little scary to me.

Any thoughts?
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Old 01-21-2017, 11:20 AM   #57 (permalink)
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Not seeing any pics...
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Old 01-21-2017, 11:20 AM   #58 (permalink)
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Yes, sorry, I hit "submit" a little too soon...
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Old 01-21-2017, 11:34 AM   #59 (permalink)
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I may be missing something, but how do you know your blade angles for pitch and cyclic with no links from the swash? Have you measured pitch and cyclic with the 3 blade head, or are you using numbers from the 2 blade head?

If I'm interpreting things correctly, you're worried about clearance from the swash links to the fuse, and have lowered the swash to compensate, but this causes an extreme angle in the swash driver at big cyclic deflection... I wouldn't worry too much about that, as if you get to full pitch and full cyclic at the same time with a scale heli, it's probably too late!
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Old 01-21-2017, 12:05 PM   #60 (permalink)
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Yes, I'm for now using the same settings in the BeastX that I had with the 2-blade head. I have to double-check, but I'm pretty sure the geometry is the same - the balls on the swash are at the same distance from the main shaft, and the pitch arms on the blade grips are the same length. But yes, I'll have to check that.
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