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T-REX 250 › New Align weighted tail blade grips versus Chinese weight test video
04-04-2009 09:56 PM  9 years agoPost 1
robrenz

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leola Pa USA

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This is a test of the Align H25095T New Metal Tail Holder which are weighted tail blade grips. When I saw these I wanted to test a set. From my experience with Chinese weights they did not look like they would have enough added weight to do much.

All tests were run on the exact same setup at the same 19000 rpm tail rotor speed.
All items were new out of the Align bag with no modifications.
The only items changed out were the complete hub and grip assemblies and/or adding my chinese weights. All other items ( pitch slider, pitch links, blades, etc.) remained identical for each run.
The baseline linkage drag at zero speed was tested with each setup and was below 0.5 oz in all cases.

Video of testing http://www.youtube.com/watch?v=wVhit93JrWE

I think that the video shows these weighted grips do not have enough weight to make a significant reduction in pushrod force.

Picture of new weighted grips below

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04-05-2009 02:45 AM  9 years agoPost 2
Gyronut

rrProfessor

Martinsville In.

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Thanks for the great work.

Rick

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04-05-2009 03:04 AM  9 years agoPost 3
caseyjholmes

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Portland, Oregon

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Cool test jig!
It is nice to see that the weighted grips do at least make a small amount of difference though. Better than stock by a slight amount. I still have not tried any weights or put my new grips on.

Will have to order me some Chinese weights soon! I like your video, very convincing evidence for me to help in my decision.

Were you running single or double bearings in the grips for this test?

Have you tried the weighted grips with adding the Chinese weights too?

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04-05-2009 04:20 AM  9 years agoPost 4
robrenz

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leola Pa USA

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Used the stock new single sheilded bearings that were included in the tail grip assemblys

I could make weights for them but whats the point? They would just be a little lighter.

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04-05-2009 04:50 AM  9 years agoPost 5
Wa11banger

rrElite Veteran

Huntsville, Al

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Great work robrenz.. It is awesome to see someone do repeatable and measureable R&D work with their product.. So where do I get these for all my helis, T700,Knight 3D, T600, Atom 500, and a T250?

Thanks
Rick

Proud member of the Quick UK, Duralite Flight Systems, V-Blade, & KBDD team

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04-05-2009 04:51 AM  9 years agoPost 6
caseyjholmes

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Portland, Oregon

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I could make weights for them but whats the point? They would just be a little lighter.
Cool. I was just wondering if adding more weight helps any. From that answer I would assume not. Thanks.

I still have trouble understanding the concept I guess of why it works. But the proof is right there in the video. I need to do more homework on the subject.

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04-05-2009 08:48 AM  9 years agoPost 7
Paul Woodcock

rrElite Veteran

Dubai - United Arab Emirates

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Hi guys

Where can i buy one of these chinese weight things?

I looks like a bit of science is involved in getting the weight correct.

Regards
Paul

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04-05-2009 03:52 PM  9 years agoPost 8
ArtK

rrVeteran

Temecula, Ca

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Chinese Weights how they work and why the align grips might still be a better option.
It comes down to centripetal force driving the weights out. The blade pitch horn wants to swing to the largest radius as it turns. That large radius is at 0 degrees pitch. As the servo adds pitch, more force is required to decrease the radius from pitch horn to the T/R shaft. If you add chinese weights 90 degrees out, they want to do the same thing but they want to go from 0 pitch to something larger. The two counter each other. The closer the weight is to the t/R shaft and the farther out from the feathering shaft the greater the effect and vice versa. If you picture everything in 3 dimensions it will make sense.

One thing to note the align grips may offer a better compromise between unloaded and loaded. The control system may hunt if it is completely unloaded causing an overshoot and maybe a reduction in gain is in order. It all depends on how fast your servo is. So maybe, even though the align grips only offer a slight reduction in forces they may be better suited for T/R overall control improvement.

NICE WORK ON THE TESTING!!! Very cool

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04-05-2009 04:14 PM  9 years agoPost 9
caseyjholmes

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Portland, Oregon

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If you add chinese weights 90 degrees out, they want to do the same thing but they want to go from 0 pitch to something larger. The two counter each other.
Aha, That makes sense. Thank you for the explanation.

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04-05-2009 06:45 PM  9 years agoPost 10
Gyronut

rrProfessor

Martinsville In.

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I had used the weights once and was not happy with the results and removed them.

The tail is much better now and I could not be happier with my setup.

Rick

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04-05-2009 08:07 PM  9 years agoPost 11
OICU812

rrMaster

Edson, Alberta, Canada

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gyro, which ones the chinese weights or the new align tr grips?

...Once upon a time there were Nitros, flybars and frequency pins...

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04-06-2009 12:45 AM  9 years agoPost 12
jadams

rrKey Veteran

East coast USA

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I bought the weights from Robin for all of my Heli's. they make a huge difference.

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04-06-2009 01:22 PM  9 years agoPost 13
robrenz

rrNovice

leola Pa USA

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One thing to note the align grips may offer a better compromise between unloaded and loaded. The control system may hunt if it is completely unloaded causing an overshoot and maybe a reduction in gain is in order. It all depends on how fast your servo is. So maybe, even though the align grips only offer a slight reduction in forces they may be better suited for T/R overall control improvement
The weights are designed to not leave the system completely unloaded. I design the weights by testing the pushrod force and making sure there is just enough tennis racquet effect left on the return to zero pitch from both directions to keep the tail system loaded enough to prevent backlash. Obviously there will be some backlash or windup when crossing 0 pitch whether you use weights or not. Most all users of my weights need to reduce their gain. The new Align weighted grips just dont have enough weight to be worthwhile.

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04-08-2009 03:34 AM  9 years agoPost 14
little-1

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usa

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250 tail grips
please axplain because i have a 250....what is important about grip weight? what are the effects? i'm confused...please help!!!!

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04-08-2009 03:59 AM  9 years agoPost 15
traderdave2

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Covington, GA

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I put the align weighted tail grips on my heli. My gain increased from 53% to 60%. I am using the smaller 3100g logitec servo. The slight reduction in servo force must have helped. I would recommend them to those using the smaller tail servos like the 3100g.

Harlan

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04-08-2009 02:15 PM  9 years agoPost 16
robrenz

rrNovice

leola Pa USA

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please axplain because i have a 250....what is important about grip weight? what are the effects? i'm confused...please help!!!!
Tennis racquet effect makes your tail system want to stay at zero pitch. It takes force to move it away from zero pitch (servo torque). Depending on the size of the heli and tail design this force can be as high as 40 oz.(2.5 pounds!). Chinese weights can reduce this force to very low levels making life easier for your servo. Usualy there is also some tail perfomance increase but not always.

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04-08-2009 02:22 PM  9 years agoPost 17
robrenz

rrNovice

leola Pa USA

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I put the align weighted tail grips on my heli. My gain increased from 53% to 60%. I am using the smaller 3100g logitec servo. The slight reduction in servo force must have helped. I would recommend them to those using the smaller tail servos like the 3100g.
Effective Chinese weights usualy reduce the gain required.

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04-08-2009 02:36 PM  9 years agoPost 18
caseyjholmes

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Portland, Oregon

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Will you be making weights that match the CF tail blades?

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04-08-2009 02:52 PM  9 years agoPost 19
robrenz

rrNovice

leola Pa USA

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Will you be making weights that match the CF tail blades?
The 40mm carbon is only .039g heavier than the 37mm plastic. The weights will work well on all the blades except the 40mm square blade which is to big anyhow.

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04-08-2009 03:04 PM  9 years agoPost 20
caseyjholmes

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Portland, Oregon

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Cool.
Thanks for all the info.
I will order a pair or two of your weights to try when I get a chance.
My little 290G will thank me for it.

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T-REX 250 › New Align weighted tail blade grips versus Chinese weight test video
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