RunRyder - how to alter delta

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Aerobatic FAI F3C Contest > how to alter delta

Dr.Ben
Elite Veteran
Location: Richmond, VA, USA

Correct.

The FFZ-II was stock on the pre-Evo Freya. The X-Spec added the metal yoke as per the pic. The SSZ-II added the metal grips.

Ben

02-06-2008 12:21 AM

F3CWNB
Senior Heliman
Location: Napier, New Zealand

Yes that is the head, I like the way it hovers & flys...

Quote
I have flown one of Mr. Dobashi's machines and Mr. Sensui's machines and they goth fly like crap compared to my machines

Did you let them fly yours???

Quote
this is because they do not add nose weight to get the machines to hover with a level swash plate and they do not use mixers to fix roll problems. They fly the sticks and fix everything MANUALLY.

Why do you think this is?

Thanks...

'Life' is Looking Up!!!

02-06-2008 08:01 AM

Bruce Naylor
Senior Heliman
Location: Swindon, Wiltshire, UK

Hi Wayne et all,

Not wanting to hijack this thread, but you said (if I have read the prev. correctly) that a centre ball (allowing lead-lag but not vertical movement) is preferable?

In tests with a Futura (floating spindle, centre ball by default, neutral CofG) hovering spot turns in wind caused all sorts of problems (tendencies to shoot of in odd directions) that magically went away when the centre ball was removed. In fact it flew better tail heavy in this configuration.

Further tests with lead/lag lock (nylon bolts screwed in either side of the feathering spindle as close to the teeter rubbers as possible) and with the centre ball removed improved loop and roll characteristics most markedly.

Ok, there are a lot of other variables - blades, flybar ratios, weights etc in the mix, but are you saying that in your tests the centre ball improved handling?

Best regards, Bruce.

"If you know what you're doing, you're not learning much"

02-06-2008 05:06 PM

Wayne Mann
Senior Heliman
Location: United States of America

Hi guys,

Sorry for the late reply, the wife has had me a little busy the last few days.

F3CWNB, yes Mr. Dobashi and Mr. Kamia (the engineer for Kyosho) hovered my machine when we went to Austria last year. They did not want to fly it around with the worlds coming up. Mr. Dobashi hovered my machine through the F3C contest maneuvers as well as he did his. We started my machine, he walked out to the box and did a couple test pirouettes in both directions and landed the model in the circle. He then proceeded to go through the hovering schedule for both schedule A and schedule B. The wind was blowing a pretty good pace. I can not tell you how impressed I was with his hovering of my machine. The reason is my machines does not hover anything like his. My machines is balanced so that when the wind hits it from any side, the trim change is the same, meaning that the model will want to nose down or up and take off in that direction. His model on the other hand is not balanced. When the wind hits the right side of the model, which would typically cause the model to nose down and go into forward flight his model would stay pretty much in a trimmed state. But when the wind would hit the left side of the model his machine would want to back up so hard you would think it was trying to do a back flip. My point being it didn't matter what he flew he was able to adjust and fly one just as good as the other.

Bruce, the center ball is only needed when you are running metal blade grips with trailing pitch arms and uncorrecting delta. Without the ball on the axle the collective is very tough to manage. With leading pitch arms and no delta to correcting delta the ball only hurts the performance of the helicopter. I'm sure that there are possibly some circumstances where this may not be the case as there are still a lot of variables that I have probably never tested.

Wayne Mann

02-08-2008 01:51 PM

Bond007
Senior Heliman
Location: Leicestershire UK

Hi

I have the option to move the delta offset between 3 settings, 0 being the center. See attached picture which is set at 0 delta.

Can you tell me which setting is corecting and uncorrecting, and what effect this would have to the model between the 3 settings ?

Thanks

Sean

Blitz Avro, Trex 500

03-02-2008 11:52 AM

mdu6
Veteran
Location: Montreal

I believe (relative to the picture), moving to the right would be adding corrective delta, left = uncorrecting.

03-02-2008 01:39 PM

RCHelicopterGuy
Veteran
Location: Michigan

Correct. In your trailing arm configuration, movnig closer to the blade grip would be uncorrecting Delta.

03-02-2008 01:46 PM

Bond007
Senior Heliman
Location: Leicestershire UK

Thanks guys

So if I flip the grips to Leading edge, would the opposite be true ?

What effect does correcting and uncorrecting delta have

Sean

Blitz Avro, Trex 500

03-02-2008 07:37 PM

RCHelicopterGuy
Veteran
Location: Michigan

Yes, it would be the opposite.

The finer details of Delta are best left explained by other people (like Wayne), but the basics of it are simple enough. Correcting Delta has the effect of reducing blade pitch as the rotor flaps upward, while non-correcting Delta has the effect of adding pitch as the rotor flexes upward.

You may also read references to it as "Flap-up nose-down Delta" (correcting) and "Flap-up nose-up Delta" (non-correcting).

03-02-2008 09:26 PM

Bond007
Senior Heliman
Location: Leicestershire UK

Thanks for the explanation

Much appreciated.

Blitz Avro, Trex 500

03-02-2008 09:28 PM

nighttrain
Senior Heliman
Location: Louisville KY

Yeah Wayne,
Thats my head. It walks off pretty dramatically when wind is on right or left side.
Doug

03-03-2008 01:05 AM

jpn
Heliman
Location: Cebu, Philippines

WayneMann,

If i read correctly, with the hirobo head, adding or removing spacers to the ball connected to the pitch arm will alter delta, does adding/removing spacers to the ball in the mixing arm to move it closer to the center also alter the delta? If I add/remove spacers to the ball in the mixing arm it can make the pitch link more upright or slanted...what is the effect?

03-13-2008 03:10 PM

Wayne Mann
Senior Heliman
Location: United States of America

Hi jpn,

Adding spacers to the ball on the mixing arm will NOT effect delta. You can add spacers in an effort to get the push rod angle straighter, but I would be careful as adding spacers will cause higher loads to be placed on the mixing arm and to the ball threads.

Wayne Mann

03-14-2008 11:00 PM

AceBird
Elite Veteran
Location: Utica, NY USA

Quote
I want the axle to be able to lead and lag, but I do not want the center of the axle to be able to move up and down as this causes collective problems.

So the ball allows the grips to lead and lag as well as teeter up and down. Am I understanding this correctly? I thought lead and lag occurred at the pivot points of the grips.

Quote
I have the option to move the delta offset between 3 settings, 0 being the center. See attached picture which is set at 0 delta.

I thought I understood delta and if I do there is no provision to adjust delta on that head.

Ace
What could be more fun?

03-27-2008 09:20 PM

RCHelicopterGuy
Veteran
Location: Michigan

Ace,

The Delta adjustment capability is there, you just can't see it. You would unscrew the pivot for the Bell-Hiller mixer and move it to a different hole on the pitch arm. There's a hole slightly to the right, and another slightly to the left.

As for lead-lag, Wayne is talking about the lead-lag of the head axle itself, not the blades.

03-27-2008 09:29 PM

AceBird
Elite Veteran
Location: Utica, NY USA

Your right I don’t see it. And I don’t see where there would be room for a hole on either side of the pivot either without breaking into each other.

Ace
What could be more fun?

03-28-2008 09:13 PM

RCHelicopterGuy
Veteran
Location: Michigan

You'll just have to take my word for it, Ace. It's there. The B/H mixer boss is covering the holes.

I'm not sure how much meat you think needs to be between the holes, but it doesn't need to be much. Look at any Bergen or MA Extreme head to see what I mean.

03-28-2008 09:54 PM

ErichF
Key Veteran
Location: Odessa, FL 33556 (Tampa Area)

Yeah, I see it, just barely peeking from behind the left side of the bell mixer base. If you mounted the bell mixer pivot bolt to that inward hole, you'd increase your negative (un-correcting) Delta. I can't see if there's another hole towards the end of the pitch arm, so you'd have to flip the grip to LE to get positive, or correcting, Delta.

Edit following Shawn's post...

You can use the outer hole to get a smidge of positive Delta.

03-28-2008 09:55 PM

RCHelicopterGuy
Veteran
Location: Michigan

Here's a picture directly from the Blitz Helicopters website.