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HomeAircraftHelicopterMain Discussion › Best Pitch Guage
07-15-2002 02:31 PM  16 years agoPost 41
CeeJay

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Alexandria, LA - USA

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MA Pitch guage correction printout
I have a copy of that MA Pitch guage correction file if anyone would like a copy of it, just email me and let me know. Or mayhaps I could put it on the Locator site so it can be accessed if enough people want it.

I have 2 of the MA guages, one older one which I put the overlay on, and a newer one that is correct from the factory. Well, as correct as a pitch guage can be I guess, after all, they are only to get you in the ball park, right? As we all know the pitch is something that is finalized in actual flying.

CeeJay

CeeJay

I love livin' in MudBug Haven!

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07-15-2002 11:26 PM  16 years agoPost 42
Bigfish

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Royal Oak, Michigan

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Pitch Error
Semi is right ........ I laid out the geometry of the Helimax on a CAD system to prove it out ...... the problem is the difference in the pivot point of the blades and the pivot of the gage.

I could not see it until I laid it out on the computer ..... but believe us - the geometry of the Helimax can not give an acurate reading at 10 deg. using it's printed scale.

We also checked several helicopters at our field with the Robart and the Helimax and discovered the same kind of errors that Keeder and his buddies found with the Helimax.

Don't get too excited about all this .......... the head speed is the most important to me - so if I use the gage to get close I am going to use the optical tach to set that ........ the pitch and throttle variables will give me the head speed I want - so as The_Dave says .... it is only a starting point. .........You might set the blades at 5 deg for your hover setting, but if the engine is screaming you will need to increase the pitch and adjust the throttle to achieve the desired head speed.

BF.

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07-16-2002 02:43 AM  16 years agoPost 43
volare

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N/A

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I'm having trouble seeing the geometry.

It seems to me the angle the blade makes compared to horizontal will always be congruent to the angle the pitch is reading, reguardless of the differing pivot points.

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07-16-2002 12:52 PM  16 years agoPost 44
SemiArticulate

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On Location

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I went back and looked at what I did a few months ago. I can't remember if I found the printed angles to be correct so I will check that today. If the Heli-max was perfect in the printed display then the blade angle and gauge angle would need to agree. I think I had found the gauge angle to be off and so therefor blade angle and gauge would get further apart. So your right, you could correct the Heli-max gage.

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07-16-2002 04:57 PM  16 years agoPost 45
Dazzler

rrElite Veteran

Ohio

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Century pitch gage
Jimmy: I went out yesterday, and purchased the levels I needed, and glued one right to the Century pitch gage, now this thing is perfect, I have a whole new look on the century gage now, it is great.

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07-16-2002 08:15 PM  16 years agoPost 46
freestyle

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Redmond WA USA

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I also don't see why different pivot points should matter. It reminds me of the myth that gyros should be placed as close to the main shaft as possible for best results.

The whole heli rotates at the same rate, so it doesn't matter where the gyro is placed (other than vibration issues, but that's a whole nother topic). By the same token, the blade and pointer are at the same angle, so it shouldn't matter where the pivots are placed. As long as the blade and the pitch guage form a parallelogram, the everything works out just fine.

The Robart pivot is a few inches below the feathering spindle, but that's not a problem. The MA and vario gauges don't pivot right at the feathering spindle axis either. Why should it matter?

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07-16-2002 11:12 PM  16 years agoPost 47
SemiArticulate

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On Location

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Yes I screwed that up. The print on my gauge is wrong. If it was right then it should not be a problem. I checked these about three months back so now I am going back and looking at what I did. I had four different pitch gauges at one time and compared them. One was mine which had a few sensors and a little computer to calculate and display the results (this was project Cabin Fever). Zero was calibrated via a machine level and the other angles via a sine table. The others gauges were robart, vario, and Heli-max. None of the last three agreed with each other. The only one that agreed with mine was the Robart. But now I am ready to agree with The_Dave and want to change my vote from Robart to 'screw it'. But just looking at it, if the Heli-max display was correct then there is no reason why it should not work very well. Sorry about the screw up I should have gone back and looked at it.

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07-17-2002 05:33 PM  16 years agoPost 48
jimmyhua

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Guam

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Screwed Up.
Semi, the print on the Helimax, and MinAir pitch gauges are wrong (well on at least the one I saw). A $0.50 protractor will verify this rather quickly. Kind of sad if you ask me.

Dazzler, for the Century Pitch Gauge, the reason for using 4 bubble levels on the pitch gauge on all 4 flat areas is (and this will come as a surprise to you) that the bubble levels will stick too! Just like the Robart gauge has a tendency to stick!!! Then again, maybe the bubble levels I got were made in China or something. Must be that cheap plastic stuff.

The only pitch gauge I know that pivots at the same point the blade does is the vario pitch gauge. It's a nice pitch gauge, never had a chance to question it's accuracy as I don't own one.

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