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HelicopterHIROBOOther › FFZ-III vibrations problem, which head to upgrade
03-19-2009 02:14 AM  8 years agoPost 21
synodontis

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United Kingdom

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move over to 120 CCPM at least if you can. 90 CCPM is plain awful and is an "unbalanced" load.

I'm surprise you need a custom built heli, there are a fair number of very good helis suitable for aerial photography that are available.

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03-20-2009 08:31 PM  8 years agoPost 22
puneetp

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Bangalore, India

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synodontis I agree 120degree is much better than 90 , will eventually move to it .

My focus is on getting a smooth head spinning. A absolutely balanced and silky smooth rotation and constant lift through out the rotor disc

The heli is made by one of the good guys in this field , copter films

Thanks,
Puneet

Machine over Gravity

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03-20-2009 09:06 PM  8 years agoPost 23
synodontis

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If I were to use a head for aerial photography work I wouldn't use the FFZ-III head. I'd use a Sylphide head (NHR-03) since it's better in the hover.

And why do you need to swing 80 cm blades to do this? For normal 90 sized blades there are some excellent ones that are very good for hovering, but with 80 cm blades you cut down your choices..

smooth spinning head is only part of the picture, you got to make sure that your engine is dial indicated properly and the drive train is smooth etc.. And also balance the blades too just in case...

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03-21-2009 01:12 AM  8 years agoPost 24
Dr.Ben

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Puneet,

Along with the usual total weight and spanwise CG checks, make sure the CHORDWISE CG of your blades is matched. Chordwise CG error can in some case all kinds shake/bumping issues d/t the way it affects the lead/lag of the blades in flight.

Ben

Team Synergy Team Futaba Team Kontronik USA
Progressive RC

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03-21-2009 10:03 AM  8 years agoPost 25
puneetp

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synodontis, please, can you tell the model number and link to head you mentioned.Also if you have more recommendations for heads for smooth hovers, I will be glad to explore.

800mm blades are required because of the weight we lift in these machines, a regular HVX200 HD camera is 3kg + Gyro stabilized mount 2 kg + custom heli with stronger frame and bearing blocks 6kg. so we are lifting 10-12kg most of the time.

This is a proven setup ,but mine is giving vibrations. I am totally open to trying new head , since I am in pursuit of very stable heli going in the future , I want to upgrade head which you, Ben and other experts will suggest here. If mine fails to give smooth results.

Ben : Thanks for the advice, that is a key point I forgot about it , I will check for both Span wise and Cord wise balancing.

Q1 In your opinion, which are most stable blades in market ( even in 690-720mm size.) which give ultra smooth hovers and smooth in slow FF?

Thanks,
Puneet

Machine over Gravity

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03-21-2009 11:09 AM  8 years agoPost 26
synodontis

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the Caliber ZG 26cc can do a 5 kg payload so I've heard, I'm sure it can stretch to 6 kg.

The Robbe Cuatro is also another option for a camera ship since it was designed for that in mind (plus many other purposes) and can swing pretty large blades.

NHR-03 is JR part number 84026. SAB 0204 are very good for hovering (675mm). There are also probably better blades than this now for hovering so I'm sure other people can chime in.

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03-21-2009 05:04 PM  8 years agoPost 27
Dr.Ben

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A set of Rotortech/Funkey SG720mm FAI blades will do anything you ask of them for your desired task. Good price, too.

Ben Minor

Team Synergy Team Futaba Team Kontronik USA
Progressive RC

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03-21-2009 07:42 PM  8 years agoPost 28
synodontis

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I really ought to get myself the Rotortech 720 SGs to try out. Unfortunately they're too big for my Eagle's head. Maybe they should fit with the SSZ-V head?

Couldn't a bog standard plastic EVO take a 5 kg payload? I don't know if it's been done so I'm asking.

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03-23-2009 01:57 AM  8 years agoPost 29
trackemdown

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Central ,VA

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You guys just blow me away with some of the advise you give. I can only hope to be able to answer questions like you do. Perhaps one I will...for now I'm in crash and burn stage and learning the hard way. The problem described here, I have seen on mine but I had a bad bearing

Grabbem-n-baggem

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03-23-2009 04:08 AM  8 years agoPost 30
Agilefalcon

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Fort Worth, Texas

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Well, without much effort at all, I've flown mine with a gallon fuel jug of water hanging off one skid....

It didn't bog the machine at all and the vertical performance was quite lively!

A gallon jug of water weighs in at 8.3lbs = 3.8kg.

This was a standard machine with 690 blades and no change in rpm or pitch. I think with longer blades and more pitch 5+ kilos would be very easy to obtain - Plus, use a set of semi-symmetrical blades would be of great benefit too.

Ben noted FAI blades. These typically are of a semi symmetrical section.

Chris.

Chris Berardi
Team BobbyJack's Hobbies

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03-24-2009 07:22 AM  8 years agoPost 31
Paul_Barsamian

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Glenview (North​Suburban Chicago)

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I've flown that camera in an Ion with 720mm blades no problem (and for 15 minute runs). Our all up weight was about 25 pounds.

14Kgs for a payload with that camera doesn't add up, why so heavy?

BTW We also owned a larger gas camera ship that was supposedly "proven" and was based on a very similar set of mechanics. It flew like a turd, was unnecessarily heavy, and we promptly sold it.

I'm with Syn on this one, 90 CCPM is going the wrong direction on the technology curve and fighting a losing battle.

If you are going to run a serious camera machine where you need to consistently fly larger cameras, the stretched Jokers with 800mm blades are the way to go and what many of the "pros" are using. If you don't like the Joker, there are a number of good machines out there that are using relatively modern control systems unlike that Vario setup.

I'm also nervous about flying 800mm blades on that head since I don't believe it was designed for blades that size. The spindle, grips and blade bolts may not be strong enough even at low head speeds. Please proceed with caution.

Son, before you can soar with the eagles you have to learn to sh** with the chickens

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03-24-2009 12:01 PM  8 years agoPost 32
synodontis

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I personally don't think the FFZ-III was designed to take 800mm blades. I'm sure that plastic blades grips can take it (unlike the Vibe 90's head where people had their blade grips break in flight when using SG 720s), it's just not in the specification. FFZ-III has 8mm spindle, Sylphide head has 9mm spindle. But all of this is discussion is extraneous if you got a machine that was built for the purpose in mind in the first place instead of mixing and matching parts from different manufacturers and hoping it flies right....

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03-24-2009 04:23 PM  8 years agoPost 33
Dr.Ben

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Actually, most current FAI blades, including the SG720's, are symmetrical. The new C schedule and its outside maneuvers have made this almost mandatory.

Ben Minor

Team Synergy Team Futaba Team Kontronik USA
Progressive RC

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03-24-2009 05:33 PM  8 years agoPost 34
Paul_Barsamian

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And to make Dr. Ben's point further, in most conditions I'd recommend symmetrical blades for camera work having tried both.

The slight increase in efficiency you get is offset by an easier to control machine. I'm running 720 NHPs which have a nice stable feel to them and are symmetrical. It makes hovering in wind a lot easier.

Son, before you can soar with the eagles you have to learn to sh** with the chickens

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03-25-2009 10:13 PM  8 years agoPost 35
puneetp

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Bangalore, India

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synodontis: NHR-03, do you know the shaft diameter for it?.Also I found this to be not readily available , can you help me with some good vendors who carry this ( I will consider this as one of the contenders for head upgrades , if required )

Paul_Barsamian:

Regarding Head Loading :
I have done a basic loading calculation for 800mm blades NHP.

- Weight is 215mm
- Moment of Arm in cm : 9.7cm(Distance from center to blade grips bolt hole approx) + 43.5Cm( from root hole to blade CG)=
53.2cm.

Please can you tell me the CG of 720mm blades from the root hole.? Also their weight , we can do the calc to see the centrifugal force .? Or you can enter them here.
http://calctool.org/CALC/phys/newtonian/centrifugal

Ben: I surely will try the heli with 720mm blades , but I guess then I need to change the gear ratio to something lesser from current 1:9.3 ( as i use 93T). Please advice.
BTW I got the part today from ehirobo.com via ups,I will trying it out this out in another 2 days.Do you 've suggestions for good Hirobo dealers in Hong Kong area or closeby eastern countries.(I know singahobbies.com)

trackemdown: What was the problem you faced bcoz of bad bearing, did the heli shake violently or was it a much milder vibrations ?

Thanks
Puneet

Machine over Gravity

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03-25-2009 11:05 PM  8 years agoPost 36
synodontis

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puneetp,

Sylphide head uses 10mm main shaft. But don't bother, get a proper heli that is suppose to swing those blades from the recommendations here. If the pros are using a Joker I would follow their lead. Also if I were to go into aerial photography I'd run electric since there's no vibration from the motor...

And NO, proper calculation of head load is a lot more difficult than that. That's an idealized calculation on a point mass. What you are forgetting is that the mass of the blade is VARIABLY distributed throughout it length, so you have to go into using calculus and what have you. We really want the moment of inertia of the blade about the blade bolt and hence we can work the force from there.... And I don't think that the outward thrust force is enough since you'll have to take into account the up and down teetering force as well (don't know how to do that since I'm not a heli designer).

but all of this is not required if you had used a head that was specced out for the job. You have been warned.

And if you run 720 blades you'll have to use 11 or 12 tooth pinion on 93 tooth main gear for HZ engine.

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03-25-2009 11:50 PM  8 years agoPost 37
Paul_Barsamian

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Glenview (North​Suburban Chicago)

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Couple of things:

1) Exactly CG of 720 blades will vary by brand and pair. Since most blades are balanced and matched, they are all a little different, sometimes vastly different. Hard to say on this one.

2) Straight out Centripital force on the blade grips is not the only factor and in fact is probably the least worrisome one. Blades flap, flex, bend, and exert a number of directional forces on a rotor head as they move in a circle around it. Longer blades exert greater leverage on a spindle, dampeners and the pivot block/bearings for example as they flap up and down during normal rotation. The sheer stress of the blade bolts and spindle bolts laterally are not the only concern.

3) Force on the larger head parts is not the only concern, linkages, mixing arms, ball links, and the 100 different radial loads on bearings all come into play. A simple calc won't really give you a good indicator here.

Unfortuneatly I don't have a good answer to figure out if the head will safely run these blades other than doing what I've done, i.e. proceeding with caution and testing to gain imperical data. I've seen one or two computer modeling systems to simulate these loads and they are extremely complex, more than I could aspire to do on paper.

Son, before you can soar with the eagles you have to learn to sh** with the chickens

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03-26-2009 12:02 AM  8 years agoPost 38
Paul_Barsamian

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Glenview (North​Suburban Chicago)

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Not to get on a soap box too much, but I've said this a million times to people, as have many of the much smarter folks than I doing aerial photo/video on this forum. Going cheap with frankenstiened machine on aerial work will only get you in trouble, when something fails (and it always does), it will fail hard.

What differentiates professionals from kids with toys strapping video cameras to them, is both the grade of equipment and the willingness to invest the time and energy to do it right. Doing professional aerial photo work is not a $2k investment, plain and simple. You might get some nice hobby shots but doing pro video work takes specialized equipment and a significant investment in time, and effort to do it safely. There is no free lunch.

off my soapbox.

And dammit Syn, you type too fast, stealing my thunder and all

Son, before you can soar with the eagles you have to learn to sh** with the chickens

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03-26-2009 01:17 PM  8 years agoPost 39
synodontis

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United Kingdom

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and another point...

most fliers fly in a field where there is a flight line. So if you crash mostly likely it will just deck into the ground into little bits - your problem, your responsibility.

Now, aerial photography might involve going into civilian airspace. And if you do that with a machine that is not up to spec because you were cutting costs here and there, well if something falls off or it crashes, there is a possibility of hitting someone. I wouldn't want that on my conscience and it will definitely put me off flying for life...

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03-26-2009 03:55 PM  8 years agoPost 40
puneetp

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Bangalore, India

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This company is respected in AV work.

All were evaluated : bergen , gsr-260, MiniCopters Maxi Joker 2( i have talked to owner 'Gerd' asking specs and loading figures) , Copter works (talked to greg about his mounts), H-C-S ,Airfoil,Benzin Vario based solutions, high spy(uk), whirly-bird , chopper-cam and more.
We found after detailed research ,'copterfilms.com.ar' to be the most suitable solution for video work for us. The company themselves does broad cast quality work along with film and ad production. They are one amongst the most experienced in video work available. Many more considerations has been made to zero in on this solution which is out side the scope of this conversation.

This has been tested for many years and constant improvements has been made to this system . I agree there are short falls.And it will be addressed. This was one of the reasons to come to hirobo section of forum (in addition to discussing with original solutions owners)

I understand the concerns raised.

- Puneet

Machine over Gravity

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HelicopterHIROBOOther › FFZ-III vibrations problem, which head to upgrade
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