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Old Feb 28, 2015, 05:07 PM
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Originally Posted by BobOD View Post
So, that Avant video says the strongest is at the lowest helical angle. I say give us straight gears then.
I like strong, noisy helicopters...always have.
Problem is the FBL controllers don't!
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Old Feb 28, 2015, 05:11 PM
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Quote:
Originally Posted by Luvmyhelis View Post
Also destroys the herringbone idea.
Actually the video doesn't say herringbone gears are bad. It says you have to mold those types of gears which means you lose some precision. Molded gears work whether they're straight cut, helical or herringbone....they just aren't as uniform as CNC machined gears...which most people already know.

With that said I don't see any reason why you couldn't CNC a herringbone gear with a custom cutting tool solution. All you need is a custom herringbone cutting tool made...may be expensive but not impossible.

Exceed Gear Manufacturing & Engineering - Herring Bone Gear - CNC Machining (1 min 17 sec)

Gear Milling (0 min 58 sec)
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Old Feb 28, 2015, 05:24 PM
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Truth is they don't need to be that exact. It is just they use this as a excuse as the reason they didn't use it. Why they just don't say it would cost too much!
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Old Feb 28, 2015, 05:29 PM
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Originally Posted by mhills51 View Post
truth is they don't need to be that exact. It is just they use this as a excuse as the reason they didn't use it. Why they just don't say it would cost too much!
+1...

Also guess how they MAKE the molds for herringbone gears? CNC...hmmm....
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Old Feb 28, 2015, 05:58 PM
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LoL! this is the second time we agree. I like your Super Suspended account!
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Old Mar 01, 2015, 01:03 AM
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Yep, any gear can be strong enough for its app. Semantics all the way. Nice work again Martin, much how I used to mount my gps module before I quit using it.
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Old Mar 01, 2015, 02:49 AM
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You should recognize that mount Randy, you were a big influence on the design. There was also another guy who had a similar GPS mount back in the day so the seed was planted.
That's what I like about these forums...ideas and the sharing of those ideas.
Good or bad they are all worth seeing and sharing as they stimulate other ideas.

I actually had a tail belt tension indicator bearing fail on the Urukay yesterday.
Heard it let go while flying, it was a "what the hell is that" moment.
Got it back on the ground and shut down, spun the rotor by hand and that bearing sounded like pop corn.
Lucky I have spares.
All my bearings should be in good shape now.
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Old Mar 01, 2015, 01:20 PM
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Ya know, I haven't ever had any of my bearings but one fail since I started using that stuff called Diamond Lube. The one that failed I had pinched too tight with shaft spacers in my secondary shaft. It eventually destroyed one of the races. Of course the logging picked it right up and I was able to get it with no drama. Instantly knew right where it was! This, before I understood the secondary head rpm vibes and was trying to eradicate them there. I have some with three years, catastrophic crashes, and over a 1000 flights, even on my tail shaft control bearings. Unfreakincanny..... Virtually all are still rolling tight. The jury was out on this stuff, but it is making me a believer.

I Just setup a new Sk720 equipped 700 Logo for a guy, herringbone gear. Which was rolling out of concentricity with a slight wobble. Which made setting up the pinion a real bugger. Nice heli though.
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Old Mar 01, 2015, 06:25 PM
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Logo 700 uses a single very large gear which means its much more difficult to mold it uniformly. For smaller dual stage gears it would be a lot easier.

It's interesting but Thunder Tiger chose a helical gear for the E820 but opted for a herringbone for the E700.
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Old Mar 01, 2015, 11:49 PM
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Quote:
Originally Posted by mhills51 View Post
Problem is the FBL controllers don't!
Good point.


Wow, that's quite a gear in that video! Is that for Helihaven's next build?
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Old Yesterday, 06:18 AM
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Checking Tail Blade Track

Any of you guys take a close look at your tail blade track?
I know there is practically nothing that can be done as there are no adjustable links for fine tuning.
I have pretty good balance on the 3 bladed Urukay tail but because the weather has been crap and I am curious I decided to see if I could determine and match blade position in much the same way I did with the main rotor, with my line level.

In positioning one blade pointing at the nose and laying my line level across the machined flats of the blade grip I was able to get a good idea of blade, or at least grip position.
I adjusted the first blade to achieve perfect "plumb" with the bubble in the line level than rotated the head to the next blade and without bumping or changing the tail pitch setting, checked the bubble position of that blade and so on.

What I found was that one blade was off zero pitch when compared to the other blades by 1/3 bubble. The other two blades were very close to each other but not exactly the same.
This was confirmed by repeating the process over and over and getting the same result...one tail blade was out of pitch compared to the others.

I swapped positions of the pitch links thinking one of them was slightly different but I got exactly the same result with the same blade being slightly off zero pitch.

It ended up being the control arms of the slider that the links connect to.
Apparently the machining tolerances for the whole assembly are such that you can effectively adjust or better match tail blade pitch by changing or rotating the "slider control arms or spider arms" to the next blade position and repeat the process of checking blade pitch.
I was able to get the tail blade zero pitch angles matched in this way.
Again all this was verified by repeated checks over and over with identical results.

The absolute proof that I did anything positive to better my tail balance will be determined by my next run and with checking the Skookum logs after flight.

Until then its just all hopeful thinking, my fingers are crossed, I'll be back with the result.
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Old Yesterday, 09:10 AM
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Geez, here I thought I was anal. lol Martin, just use a small metal square. Nock it into one tri tail grip at the corner of the square, flat against the inner side. Then use the angled runners of the square to make sure the other grips are flat as you press it to the same inner grips. Sound easier?

Well, I may snap today and just order in my gob parts that I need to finish up the herd. The weather is looking to hit 60 by this weekend. I did fly Sunday in about 44 deg weather. Bloody beautiful day and we had a blast. Something in the cold air mass that allows these flying blades of death to grab air like nothing else. Glad I had my long johns on however.....
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Old Yesterday, 01:43 PM
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Tail Blade Track Check Success!

Being anal has its rewards, and I know you understand that.

Using the bubble level to check and match the tri tail blade pitch settings to "0" by re-indexing the slider to different blade positions until they were closely matched worked really well for me.
I tell you I have flown hundreds and hundreds of Goblin 770 flights and 60 Urukay flights to date and always heard the famous Goblin tail rotor roar, it was always present, its just what they do.
I knew immediately on spool up to flight RPM I did something very good.
The tail rotor was just a muffled hum, I couldn't believe the change from that small pitch adjustment I did on the tail.
See the charts. The tail vibe went from a good 2.2 to a much better.6, all because of that small pitch change to match pitch settings on all three blades.
The overall vibe score on the Skookum went from a 1.5 to 1.

The square sounds like a good idea also LMH but for my old eyes the bubble is a little easier to see the differences between individual blade pitch.
See the photo.
And it's very quick for just a check. Position the blade horizontally pointing at the nose. Put the line level on the machine flats of the grip (see the photo).
Adjust the blade angle to achieve a center bubble.
Rotate the next blade into position to see if it matches the first blades center bubble and so on to the third blade if you have three.

Make whatever adjustments to match pitch angles. In my case all I had to do was reposition the slider spider until I found the closest match in pitch angles.
Super Duper.

If repositioning the slider didn't do it for me I was actually going to make a tool that would bend the slider arms to achieve perfect pitch between blades. Since the arms are aluminum I thought that would be fairly easy to do and get them dead accurate. Didn't need to though, lets here it for machine tolerances!

I think also that if you had a worn out or lose tail rotor this process would not work because of the sloppiness already in the linkage, it just wouldn't be able to give you an accurate reading for blade position.
This would be a great thing to check on a new build, then forget about it.
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Old Yesterday, 06:42 PM
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United States, FL, Palm Coast
Joined Mar 2012
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Quote:
Originally Posted by A VIKING View Post
Being anal has its rewards, and I know you understand that.

Using the bubble level to check and match the tri tail blade pitch settings to "0" by re-indexing the slider to different blade positions until they were closely matched worked really well for me.
I tell you I have flown hundreds and hundreds of Goblin 770 flights and 60 Urukay flights to date and always heard the famous Goblin tail rotor roar, it was always present, its just what they do.
I knew immediately on spool up to flight RPM I did something very good.
The tail rotor was just a muffled hum, I couldn't believe the change from that small pitch adjustment I did on the tail.
See the charts. The tail vibe went from a good 2.2 to a much better.6, all because of that small pitch change to match pitch settings on all three blades.
The overall vibe score on the Skookum went from a 1.5 to 1.

The square sounds like a good idea also LMH but for my old eyes the bubble is a little easier to see the differences between individual blade pitch.
See the photo.
And it's very quick for just a check. Position the blade horizontally pointing at the nose. Put the line level on the machine flats of the grip (see the photo).
Adjust the blade angle to achieve a center bubble.
Rotate the next blade into position to see if it matches the first blades center bubble and so on to the third blade if you have three.

Make whatever adjustments to match pitch angles. In my case all I had to do was reposition the slider spider until I found the closest match in pitch angles.
Super Duper.

If repositioning the slider didn't do it for me I was actually going to make a tool that would bend the slider arms to achieve perfect pitch between blades. Since the arms are aluminum I thought that would be fairly easy to do and get them dead accurate. Didn't need to though, lets here it for machine tolerances!

I think also that if you had a worn out or lose tail rotor this process would not work because of the sloppiness already in the linkage, it just wouldn't be able to give you an accurate reading for blade position.
This would be a great thing to check on a new build, then forget about it.
#HowToSatisfyYourOCD
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Old Yesterday, 06:56 PM
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Quote:
Originally Posted by IntegrityHndywrk View Post
#HowToSatisfyYourOCD


I was up at three this morning thinking about this.
I'll sleep good tonight.
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