Remove Axle Pivot. Headmod for F3C

[devilfish]

Hi

Back in the days, Hirobo also used the Axle Pivot style of headblock.
For us that flew F3C, the trick here whas to remove the Axle Pivot, and make the axel a "free float" design.
This made the heli hover better.
Has anyone tried this on the 766?
Is it even safe to try on this model?
The Hirobo models hade much taller mainmast, so boom strikes whas less prominent.

Thanks

[alan]

I have removed the pivot on the E5 head before.  I did this on a scale project to allow for lower head speeds and softer dampening.  Of course no 3-D or loops for that matter.  I would try using all orange dampeners first.

Cheers

Alan

[Thunder Fighter]

I've started by using the softer damper on the outside and the harder on the inside. I haven't had many flights on it though with this setup so cant say if it needs to be softer yet. I've got my first competition with it coming up in a few weeks so wont have a chance to try any other serups before then.

//Dennis.

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[Mike Spano]

any updates on this? i want to set my 766 up for F3C as well. thanks.

[Thunder Fighter]

I have flown a couple of F3C competitions with my 766 now. Mechanically the only changes have been the damping as I mentioned above where I put the soft dampers on the outside of the headblock and of course the speed up tail. I didn't remove the pivot.

The Heli hovered pretty well with a CGY tuned for F3C but I think the biggest issue is the light disc loading with this setup making the Heli more sensitive to wind gusts with the Heli moving vertically, not being blown off position as much. I have flown with Rotortech 760 FAI blades as well as Synergy 766 blades, both were fine for the hovering but the auto performance was better with the Rotortechs. In the aeros both blades were good with excellent tracking and plenty of cyclic and collective authority. I think 640mm FAI blades might be a better match for gusty conditions for the hovering stopping the machine being blown up and down as much.

I am in the process of stripping down the 766 and selling it as I am going to setup a new model for F3C competition.

//Dennis.

[Mike Spano]

since the head has no delta built in, I don't think removing the pivot ball will help much anyway. if it had some built in, then it would help with wind/collective in hovering. I am considering going to the 716mm F3C blades for more stability too.

[Robert "Full" Montee]

For my E5 running 716mm blades I pulled the pivot. I use the stock dampers, being the dampers are hard I had no issues.
Through the Summer I did not notice a difference so I popped the pivot back in.

The disk loading difference between my E5SS and a 766 running 766mm blades is close. My E5SS has lighter disk loading.
If you have a 766 running 806 blades weighing 13.5lbs, than your disk loading becomes lighter than my E5.

To remedy a heli jumping up down in the wind I have an adjustable pitch curve that I can adjust with the knobs on the radio realtime. Also for the CGY I utilize the gain multiplier and use much higher gains in hover. Careful with the multiplier because it will also multiply the gain on your head for aerobatics.
Last but not least many run a lower headspeed in hover to conserve power, if you are running efficiently enough try 100rpm more and compare the stability.

Dennis, what is the ready to fly weight of your 766 running 766mm blades?

[Thunder Fighter]

I don't have a weight on my 766 and I'm away from home for a couple of weeks.

I am running the gain multiplier to increase the hovering gain as I hit 100% for hovering and my pitch curve is already adjustable. I just find in gusts the Heli jumps up and down as though it's being blown around compared to the much heavier loaded full fuse models I am competing against. I am probably on the lower limit for headspeed, I do need to try going up a little as this will probably help, I do have capacity in hand as I land with about 40% remaining for P schedule and 30% for F schedule.

As I mentioned I am going to start from scratch with a new model now our season is over so I will strip the 766 as soon as I get home as my new kit has arrived ready to build.

//Dennis.

[Robert "Full" Montee]

Ran some disk loading math.
The 766 running 716mm blades at 13lbs ready to fly still doesn't get close to some of the fuselage models I've discussed with the US F3C team when comparing disk loading.
FAI rules show 6.5kg as max weight ready to fly. That is 14.3 pounds.
A TT Raptor E720 in a fuse like Nick flew in 2015 Worlds was near the max weight if memory serves me well.

My hovering head gain is higher than 100 as viewed from the CGY.
What is the next model you are setting up for F3C Dennis?

[Thunder Fighter]

Another "out of left field" choice for F3C competition.

I am associated with Heli Professionals Soxos helis now as the Australian distributor and have a kit with various parts from the range put together to optimise it as much as possible for F3C. It is based on a DB7 but with different frames, canopy, 800 boom, etc and different head block options. It is purely something for me to play with and see if I can make a suitable model for competition. I may put a fuse or even try to modify a boom cover at some stage, but for now will just leave it as a pod and boom.

//Dennis.

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