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05-23-2018 02:54 AM  87 days agoPost 61
Mojave

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Palos Verdes, Ca. USA

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I see what you're getting at. That is a very space limited profile. You may want to consider using a pair of hardened main shafts. Another idea is to use a hollow core main shaft. Hollow centerless ground shafts are typically stronger than solid shafts. Good luck.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

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05-23-2018 10:31 AM  87 days agoPost 62
goodhunting

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Slovenia ... somewhere in Europe

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here is some motivation for this awesome project...

Watch at YouTube

and the build thread on a german forum...
https://www.rc-heli.de/board/showth...t=261585&page=8

really looking forward to your solution....
gh

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05-23-2018 01:14 PM  87 days agoPost 63
garyl

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Barry, Thanks for the info. I am currently using 1566 carbon steel shafts which I hope will be up for the task.

Goodhunting, Thanks for posting that, cool! His project looks like 1/6th scale or better which gives more space for things, but not much more. I can't view any of the photos or read the text on that forum

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05-23-2018 01:22 PM  87 days agoPost 64
goodhunting

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Garyl... it is in German... and I just re-checked ther eis no option for English... unless you use google.
you would need to register to see the photos but there are quite a few of them and amongs them his solution to the extended mainshafts...

perhaps it is more obvious out here....

Watch at YouTube

gh

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05-23-2018 01:34 PM  87 days agoPost 65
goodhunting

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I borrowed two pictures, showing the main shaft solutions...

gh

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05-23-2018 04:49 PM  87 days agoPost 66
garyl

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I see he is using the BD3x which does not have the tandem software, he must have a custom made tandem mixer. My mechanics design looks like his just smaller.

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05-27-2018 04:41 PM  83 days agoPost 67
garyl

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Designed the test bed landing gear and used a spare set of landing gear tubes from a vario cobra kit I turned into a Z model. The base plate is made from 3mm carbon fiber. I used 3/8" square tubing for extra structural support under the carbon fiber plate. As it sits right now everything is very rigid.

The XNOVA 450KV motor finally arrived and fits nicely.

The Talon HV120 fits in the front with 3D printed side mounts bolted into the carbon fiber plate.

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05-27-2018 04:48 PM  83 days agoPost 68
Pistol Pete

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Seffner, FL

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You should have a live stream to your shop and charge for that heli porno.

Outstanding.

~~Enjoying the hobby one flight at a time~~

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05-27-2018 07:01 PM  83 days agoPost 69
goodhunting

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Looks awesome.

Klem

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05-31-2018 01:34 AM  80 days agoPost 70
garyl

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Thanks guys.

I designed a gyro and receiver mount that screws to the carbon fiber with 2mm screws, printed it using PETG material.

All of the servo rods are made and mounted.

Next up will be the rotor heads and making the rods that go from the swash to the blade grips.

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06-03-2018 10:28 PM  76 days agoPost 71
garyl

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I ordered Vario swash drivers but I do not know when they will arrive. So in order to prevent that from holding up the maiden flight I made my own.

The rods going from the swash to the blade grips are 3mm diameter with SAB links.

The digital pitch gage is simply zeroed out on the upper frame spacer and then attached to the main blades to set the pitch range for each rotor head.

I just have to setup the speed control and it will be ready for the maiden flight this Friday at Joel's scale fun fly. Lucky for me the two tandem experts Joel and Sandy will be there to check my work.

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06-04-2018 03:07 PM  75 days agoPost 72
bwellmaker

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Long Island

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Gary,

You are a madd man. I cant wait to see this machine in person.

We will be at the field hopefully around 1 or so.

B

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06-04-2018 04:01 PM  75 days agoPost 73
garyl

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Looking forward to see you guys again. The weather is looking perfect so the weather man says right now, he is never wrong right
Just received an email from Joe this morning saying the swash drivers are in, this only figures since I spent the time to make my own yesterday.

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06-04-2018 05:18 PM  75 days agoPost 74
GyroFreak

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Orlando Florida ...28N 81W

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Somehow you will need nerves of steel on the first lift off and/or flight.
Make sure some videos it for our enjoyment.

I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?

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06-05-2018 12:50 AM  75 days agoPost 75
oldfart

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Vancouver, Canada

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Awesome Project Gary. Two thumbs up for sure

Phil

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06-21-2018 02:09 AM  59 days agoPost 76
garyl

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Update; A first flight was attempted but only the right skid came off the ground. The mechanics are alive but are in need of a redesign and I will explain why.

My original control theory of using the tandem software in the 3SX will not work correctly using the differential collective pitch (DCP) in the roll axis. DCP will cause more of a yaw than a roll due to the torque differences DCP creates in each rotor head. DCP works fine in a tandem rotor due to the greater distance between each rotor shaft, things change with intermeshing rotors with the shafts closer together.

I have been communicating with a few other experienced individuals who have successfully built and flew intermeshing rotor helicopters and they have shared what will actually work.
Each swashplate will have to move in a way we are all familiar with, but with an exception of yaw which will require differential cyclic pitch.
For forward each swash will tilt forward together.
For roll each swash will tilt left or right together.
Yaw will require each swash tilting in opposite directions, differential cyclic pitch (DCP).
Collective pitch each swash will go up or down together.

In order to make this all happen the V rod configuration has to go in the trash and a three or four servo ccpm configuration has to be added into the mechanics design. This of course will require a new mixer as well. As they say "back to the drawing board".

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06-21-2018 03:06 AM  58 days agoPost 77
Joel Rosenzweig

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Marlborough, MA - USA

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Gary,

My mixer will do that mixing for you. Tandem mode supports both swashplate tilt and DCP for the pitch axis (aileron axis for your KMAX) In your case, you’d turn the mixing ratio for DCP to 0% and use some non zero ratio for roll axis mixing. The bottom line is that it will do what you want. It supports 3 and 4 servo ccpm modes. You can still use your Demon just like I use one in my Chinook with the same mixer setup.

Joel

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06-21-2018 02:42 PM  58 days agoPost 78
Jim Ryan

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Cincinnati, OH

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I was late discovering this thread; Gary contacted me about an old YouTube video of a test flight for my Kaman Huskie mechanics.

Gary, I'm sorry the 2-servo control setup didn't work out for you. That looked like a really elegant solution, and it's a shame about the yaw/roll coupling. Fitting the mechanics into the super-narrow K-Max is certainly a bigger challenge than the boxy Huskie.

It sounds like you're heading for the same control setup I used for my Huskie mechanics, with both swashes tilting in parallel for pitch and roll and with differential fore/aft cyclic for yaw control. This has worked pretty well for my Huskie; roll and yaw are pretty docile, but it's more sensitive (or less stable) in pitch than I would like. In my case, I used a DigiMix 3 programmable mixer to mix the Elevator and Rudder outputs from my FBL, and in my case I used a Skookum 720.

Joel, good to see you on this thread. I'm sure your mixer unit is probably a better approach than the electronics I cobbled together. Gary mentioned you were recommending a BD 3SX for the FBL unit. I chose the Skookum because it was more resistant to vibration than my previous choice, but I have a spare 3SX if you think it would be markedly superior to the Skookum. I'd appreciate your comments on that.

Keep at it, Gary! This is a really impressive project, and gets me enthusiastic about doing more tweaking on my Huskie.

Jim

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06-21-2018 02:43 PM  58 days agoPost 79
Jim Ryan

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Cincinnati, OH

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Photos of my Huskie...

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06-21-2018 09:38 PM  58 days agoPost 80
JuanRodriguez

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The Villages, Florida

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Jim Ryan
Photos of my Huskie...
Where ??

Been there, done that and old enough to know better.....

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