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Logo 600 › 600 tail rod question.
12-01-2011 01:44 AM  5 years agoPost 1
Donnie Baker

rrNovice

Indianapolis

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I'm building my first logo and from the directions it appears you epoxy the tail ball links right tight up against the control rod. Is this tail not adjustable the way the Aligns are?

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12-01-2011 01:46 AM  5 years agoPost 2
johnnie eagle

rrApprentice

Florham Park, NJ​07932

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They really aren't adjustable, but if your using a VBAR it's perfect where the manual tells you to put it.

Team Minicopter - Peak Aircraft, Team Kontronik USA

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12-01-2011 01:51 AM  5 years agoPost 3
Donnie Baker

rrNovice

Indianapolis

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Thanks guy. So you really do just bottom the ball links against the tail rod huh? I guess that couldn't be any simpler.

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12-01-2011 02:51 AM  5 years agoPost 4
CRaZeD

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Catlettsburg, Ky

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ok after reading this I have a question then....i just recently got the carbon Kaos frames for my logo 600 (my 1st logo purchased used) and the tail rod seems just abit short with these frames and doesnt allow equal throw left to right and I thought that this was possibly a homemade tail rod and that the original logo tail rod was adjustable but after seeing this i guess i need to find another alternative...any suggestions??

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12-01-2011 01:24 PM  5 years agoPost 5
Eury

rrProfessor

Dover NH

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Personally, I always make mine so there is some adjustment. There is no way their measurement can be perfect in a heli with a belt drive tail.

RE: Kaos frames, the link measurements are a little different for everything on the Kaos. I used the regular Logo rod just built with a little adjustment in it, but really you can use anything, tail rods are pretty universal. If I need a replacement I usually just make one out of carbon rod and a couple links.

Nick Crego

Citizen #0168

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12-01-2011 02:13 PM  5 years agoPost 6
kruuuzn

rrKey Veteran

Traverse City, MI

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I just ran across the same thing on my 600SE build. The directions show gluing the links, threaded rods, and carbon rod all together with the links bottomed out on the carbon rod. When I hold this up to the tail and servos balls it looks like the setup would give me the perfect amount of positive pitch on the tail blades but I just cant get over the fact there's no adjustment. I mean, even adjusting the belt tension would change the pitch on the tail blades. I used to set up my other helis in rate mode but I guess with the V-bar that's old fashioned and no longer necessary?

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12-01-2011 02:27 PM  5 years agoPost 7
hams

rrApprentice

Ohio

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If you really need adjustment, simply cut the carbon rod shorter and glue the threaded rod in first. I use JB weld.

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12-01-2011 02:57 PM  5 years agoPost 8
kruuuzn

rrKey Veteran

Traverse City, MI

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I'd just as soon go without the adjustment if that's the way everyone is flying them. It's just one less thing to worry about.

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12-02-2011 12:36 PM  5 years agoPost 9
cshutchinson

rrNovice

Florence, SC

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Can the same assumption be made for the Logo 400 and 400SE? I just finished one and had to expose 1/8" of threads on each end. I wasn't getting stop to stop throws even with the servo wheel moved out 1.5mm beyond recommendation and the throws at 120 / 120.

It flew like a champ today so I am leaving it as is.

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12-02-2011 10:50 PM  5 years agoPost 10
dw12

rrApprentice

pennellville new​york u.s.

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I have trimmed the rods and use JB Weld to have adjustment,Have hundreds of aggressive flights with no problems.

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12-04-2011 02:14 PM  5 years agoPost 11
Sillyness

rrVeteran

Little Rock AR

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Maybe this will clear it up a bit for you.

What is the one constant that has the least amount of thermal expansion and contraction in the tail boom system? The belt.

If you are adjusting the belt tension, you are actually setting the belt back to the same place every time by compensating for the metal boom's lengthening and shortening.

The distance from the frame to the tail bell crank is set, at all times, by that fiber or kevlar reinforced belt. It's a pretty solid measure for Mikado to calibrate the length of the carbon rod to. The length of the boom and tension adjustments don't really matter at all!

In case you can't tell, I butt my links up against the rod. Set it and forget it. If it's off a little, the vBar doesn't seem to care. Mine are pretty dang centered though.

I also have a carbon boom on one of my birds. The belt tension never changes.

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12-04-2011 02:29 PM  5 years agoPost 12
cshutchinson

rrNovice

Florence, SC

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Sillyness,

I think you are correct in your conclusion, but wrong in the facts leading to the conclusion.

You aren't adjusting the belt b/c the boom got longer or shorter due to temperature. You are adjusting the belt b/c the belt itself got longer or shorter due to temp changes.

The distance from the frame to the bell crank is set, at all times, by the aluminum tail boom itself, not the belt.

Look at these coefficients of thermal expansion to see my point....

http://www.engineeringtoolbox.com/l...ients-d_95.html

However, I think you are spot on with the rest of your post and conclusion.

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12-05-2011 12:49 PM  5 years agoPost 13
Sillyness

rrVeteran

Little Rock AR

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Sillyness,
I think you are correct in your conclusion, but wrong in the facts leading to the conclusion.
You aren't adjusting the belt b/c the boom got longer or shorter due to temperature. You are adjusting the belt b/c the belt itself got longer or shorter due to temp changes.
The distance from the frame to the bell crank is set, at all times, by the aluminum tail boom itself, not the belt.
Look at these coefficients of thermal expansion to see my point....
http://www.engineeringtoolbox.com/l...ients-d_95.html
However, I think you are spot on with the rest of your post and conclusion.
Lets think this through "out loud". I think you kinda proved yourself wrong with the table.

Note that the table says EVERYTHING expands when heated, and EVERYTHING contracts when it cools. This is true of everything but water due to hydrogen bonding, but that's a separate little miracle.

So, if the belt is the piece doing the expansion and contraction, when you take a heli from a cool house to the hot sun the belt should loosen because it gets bigger faster than the metal, right? It doesn't. it gets TIGHTER. Why? The boom expanded more than the belt, acting like you were pulling on the tail case to increase belt tension.

Conversely, a heli taken from the house to the 32F freezing conditions we have right now should, per your thoughts, make the belt tighter (belt should shrink more, right?). In fact, it gets very very loose. The only explanation is the boom shrank more than the belt.

I'll drive the point home with this:

I have a carbon boom now on one Logo and the belt tension never really changes from 32F to 100F. The boom materials must be matching the belt materials expansion/contraction rates, right? Graphite, per the table you attached, has a coefficient of 7.9 (metric). Aluminum has a coefficient of 22.

It really is the aluminum boom getting longer and shorter with different temps that requires belt adjustments. Promise! Aluminum in fact has one of the highest expansion/contraction rates of any common metal.

I should note that in the table, I'm not sure where kevlar sits.

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12-05-2011 01:00 PM  5 years agoPost 14
cshutchinson

rrNovice

Florence, SC

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Yes, point taken, I was the one with it backwards. Sorry for the mixup and I certainly learned something through this. Thanks for the explanation, well written!

I made the incorrect assumption that the belt being 'hard rubber' at 77 had to be expanding more, but I did not back that up by the actual observation on my end. And, maybe the belt really isn't hard rubber at all.

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12-05-2011 01:04 PM  5 years agoPost 15
cshutchinson

rrNovice

Florence, SC

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Sillyness,

Damn, you are spot on.... Read this...

Kevlar has other advantages besides weight and strength. Like graphite, it has a slightly negative axial coefficient of thermal expansion, which means Kevlar laminates can be made thermally stable.

from....

http://composite.about.com/od/about.../l/aa050597.htm

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12-05-2011 01:05 PM  5 years agoPost 16
cshutchinson

rrNovice

Florence, SC

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That is one great reason to use a CF boom... Still shakin' my head about how wrong I was sorry!

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12-06-2011 12:44 AM  5 years agoPost 17
Sillyness

rrVeteran

Little Rock AR

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Nobody is right or wrong. We make conclusions based on observation tempered with assumptions. Noone can know everything because no one can observe everything and noone is perfect at assumptions. I learn a ton from you guys!

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12-06-2011 09:51 PM  5 years agoPost 18
marcosp

rrApprentice

Buenos Aires,​Argentina

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Nobody is right or wrong. We make conclusions based on observation tempered with assumptions. Noone can know everything because no one can observe everything and noone is perfect at assumptions. I learn a ton from you guys!
Dude, that is like a zen kung fu frase of the year for me!!! No, really, never heard it that way and it's soooo true. It changes the way you think about everyone else. Really nice. I'll take it as a new years gift from you to me. Thanks.

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03-14-2013 06:50 AM  4 years agoPost 19
smittylube

rrVeteran

Santa Cruz, CA

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Well I just observed exactly that. I had been setting the tension on my 600 at or near 50deg.
today it was 85 ish and the belt felt really tight so I loosened it up. then I'm sticking in a battery to get ready for tomorrow and feel the belt- it feels like its gonna come off. About 50 or 55 deg., its super loose. All I could think was it had to be the boom expanding. I guess I'll need to check and be sure its either warm out or adjust as needed. I cant imagine what it would be at 32 degrees out.

mental note to self - expect belt tension changes.

Steve

RPM is your friend..................................until you crash

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03-14-2013 11:52 AM  4 years agoPost 20
kruuuzn

rrKey Veteran

Traverse City, MI

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After my belt slipped off, took out the tail drive pulley, and put my heli through the trees into a snow bank 1/4 mile down range while flying in 8°F weather I spent the extra $25 for a carbon fiber boom.
I love it.

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Logo 600 › 600 tail rod question.
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