RunRyder RC
WATCH
 9 pages [ <<    <     1     ( 2 )     3      4     NEXT    >> ] 13728 views POST REPLY
HomeAircraftHelicopter
e-
SAB
Other › No swash driver
02-01-2012 10:09 PM  6 years agoPost 21
TomC

rrKey Veteran

Gold Coast, Queensland, Australia

My Posts: All  Forum  Topic

I have watched all the Goblin videos in the web and I have yet to see any really good aileron tick-tocs. The rear tail always seems to bob up and down. I thought this was maybe due to the draggy oversized boom but perhaps it indicates some phasing issues?

If I owned a Goblin (and I don't plan to buy their current version) I would fit a pair of swash follower links to the head block. Of course you would need to drill/tap the swashplate to add a couple more inner balls since the Goblin swash only has 2 inner balls (another brilliant Italian design feature, lol!).

Cheers,
TomC

Nqx,Mcpx-BL,300x,450x,500x,550x
Ion-x, 10s ,SS
TT X50E 10s, HC3-Sx

PM  EMAIL  GALLERY  Attn:RR  Quote
02-01-2012 10:16 PM  6 years agoPost 22
heliaddict2424

rrApprentice

SCV SoCal.

My Posts: All  Forum  Topic

I thought the goblin isn't interesting for you?
-Klaus
LM@O.. To be honest I still don't know but I already paid for the thing in full a long time ago and have all my electronics. I think I will give it a shot unless HD will refund my money LOL..

Team MikadoUSA Team Scorpion

PM  EMAIL  GALLERY  Attn:RR  Quote
02-01-2012 11:28 PM  6 years agoPost 23
hams

rrApprentice

Ohio

My Posts: All  Forum  Topic

You don't seem to have understood the problem raised by heliaddict2424. Don't forget that there are two blades and each creates opposing forces on the head that cancel each other:
http://www.helifreak.com/showpost.p...03&postcount=54
http://www.helistart.com/RotorheadTypes.aspx
You are not taking into account the mass of the heli. It takes force to drag it along with the disk resulting in the teetering of the feathering shaft. If the head and grips were solid and absolutely NO dampening will happen then it would be ok. As is nope.

If you have access to a compass head or an align dfc head try the following:

Remove the ball links from the swash. Let them hang straight down next to the swash, but not snapped onto the balls. Teeter the feathering shaft and observe. You will see that both downlinks will move in the same direction resulting in the downlinks fighting against each other.

Running the heli at 2000 + rpms results in a ton back and forth bending forces and I am not comfortable with that long term.

PM  EMAIL  GALLERY  Attn:RR  Quote
02-01-2012 11:31 PM  6 years agoPost 24
heliaddict2424

rrApprentice

SCV SoCal.

My Posts: All  Forum  Topic

You are not taking into account the mass of the heli. It takes force to drag it along with the disk resulting in the teetering of the feathering shaft. If the head and grips were solid and absolutely NO dampening will happen then it would be ok. As is nope.
DEAD ON and a solid head with no dampening would create a new problem just ask Jan Henseliet why he went to a teetering head.

Team MikadoUSA Team Scorpion

PM  EMAIL  GALLERY  Attn:RR  Quote
02-01-2012 11:35 PM  6 years agoPost 25
hams

rrApprentice

Ohio

My Posts: All  Forum  Topic

DEAD ON and a solid head with no dampening would create a new problem just ask Jan Henseliet why he went to a teetering head.
Exactly

IMOP the Compass head, Align DFC head and the Goblin heads are pure marketing and poor engineering.

PM  EMAIL  GALLERY  Attn:RR  Quote
02-01-2012 11:44 PM  6 years agoPost 26
heliaddict2424

rrApprentice

SCV SoCal.

My Posts: All  Forum  Topic

+1

Team MikadoUSA Team Scorpion

PM  EMAIL  GALLERY  Attn:RR  Quote
02-02-2012 01:38 AM  6 years agoPost 27
3Dmuse

rrApprentice

Ontario, Canada

My Posts: All  Forum  Topic

You are not taking into account the mass of the heli. It takes force to drag it along with the disk resulting in the teetering of the feathering shaft. If the head and grips were solid and absolutely NO dampening will happen then it would be ok. As is nope.
You are forgetting that the blades are flexible and they are the first of all parts in the head to flex. I think the blades will absorb completely the very small angles that heliaddict2424 is concerned about. And if not, I think the downlinks will change the pitch of the blades in opposite directions and that will re-balance the rotorhead.
Remove the ball links from the swash. Let them hang straight down next to the swash, but not snapped onto the balls. Teeter the feathering shaft and observe. You will see that both downlinks will move in the same direction resulting in the downlinks fighting against each other.
I am not sure what direction you are talking about: vertical, horizontal, in between? I am talking about a vertical direction and I think that one link will move up, while the other down.

To me, the Goblin seems to be a "Hingeless" type of rotorhead, which seems to work in "real" helicopters just fine if the head is strong enough:

http://www.helistart.com/RotorheadTypes.aspx

"Unlike a fully articulated system, moments are transmitted to the rotorhead, which must be able to cope with these forces."

PM  EMAIL  Attn:RR  Quote
02-02-2012 02:05 AM  6 years agoPost 28
hams

rrApprentice

Ohio

My Posts: All  Forum  Topic

horizontal arc from the swash balls.

PM  EMAIL  GALLERY  Attn:RR  Quote
02-02-2012 02:08 AM  6 years agoPost 29
3Dmuse

rrApprentice

Ontario, Canada

My Posts: All  Forum  Topic


horizontal arc from the swash balls.
Unless I completely misunderstood heliaddict2424, he was concerned about vertical movement of the links? That's how I interpreted his drawings.

As for the movement in the horizontal arc of the links in the Compass, Goblin, or Align DFC rotorheads, I don't think it's a problem as the movement is very small. I would not be more concerned about it than I am about the plastic ball links in a "traditional" RC flybarless head that we all know have the habit of popping off the balls when you least expect them.

PM  EMAIL  Attn:RR  Quote
02-02-2012 02:14 AM  6 years agoPost 30
hams

rrApprentice

Ohio

My Posts: All  Forum  Topic

I believe you have misunderstood his drawings.

This design contradicts itself. It has head dampeners, but also has completely rigid swash to grip links to drive the swash. They fight each other.

PM  EMAIL  GALLERY  Attn:RR  Quote
02-02-2012 02:48 AM  6 years agoPost 31
3Dmuse

rrApprentice

Ontario, Canada

My Posts: All  Forum  Topic

The forums are full of quasi-science, we should all educate ourselves as much as possible. I recommend these books to everyone willing to invest some effort:

http://www.amazon.com/Principles-He.../ref=pd_sim_b_5
http://www.amazon.com/Helicopter-Pe...5/ref=pd_cp_b_2

PM  EMAIL  Attn:RR  Quote
02-02-2012 02:55 AM  6 years agoPost 32
heliaddict2424

rrApprentice

SCV SoCal.

My Posts: All  Forum  Topic

Its just simple engineering.. The design creates problems period if it aint broke dont fix it just to be different.

Team MikadoUSA Team Scorpion

PM  EMAIL  GALLERY  Attn:RR  Quote
02-02-2012 03:09 AM  6 years agoPost 33
TomC

rrKey Veteran

Gold Coast, Queensland, Australia

My Posts: All  Forum  Topic

hams and heliaddict2424, would installing swash follower links help or would they actually make this potential problem worse by creating another pair of stress points? Thanks.

Cheers,
TomC

Nqx,Mcpx-BL,300x,450x,500x,550x
Ion-x, 10s ,SS
TT X50E 10s, HC3-Sx

PM  EMAIL  GALLERY  Attn:RR  Quote
02-02-2012 03:18 AM  6 years agoPost 34
hams

rrApprentice

Ohio

My Posts: All  Forum  Topic

Adding a swash follower is pointless imop. You still have completely rigid parts fighting the non rigid dampeners. If you want low parts count and no binding, then I would run a head with the swash drivers attached to it with normal links to the grips. Eg. MA Fbl heads. I actually prefer separate swash drivers like the mikado setup because you can fine tune phasing for different blades.

I have learned a few things since I got into this hobby and one is that if it is shiny and new, people will flock to it, regardless if it is a good design or not

PM  EMAIL  GALLERY  Attn:RR  Quote
02-02-2012 03:29 AM  6 years agoPost 35
TomC

rrKey Veteran

Gold Coast, Queensland, Australia

My Posts: All  Forum  Topic

Thanks hams!

Cheers,
TomC

Nqx,Mcpx-BL,300x,450x,500x,550x
Ion-x, 10s ,SS
TT X50E 10s, HC3-Sx

PM  EMAIL  GALLERY  Attn:RR  Quote
02-02-2012 04:14 AM  6 years agoPost 36
3Dmuse

rrApprentice

Ontario, Canada

My Posts: All  Forum  Topic

Its just simple engineering.. The design creates problems period if it aint broke dont fix it just to be different.
I don't know how you can be so certain that the design creates problems. I also am not sure if any of the persons who posted in this thread has the technical competence to evaluate the design only by looking at pictures.

BTW, I'm sure the cars in 1900 seemed just fine to the people of those times.

I guess we all have to live and see how the Goblin will do.

PM  EMAIL  Attn:RR  Quote
02-02-2012 06:20 AM  6 years agoPost 37
heliaddict2424

rrApprentice

SCV SoCal.

My Posts: All  Forum  Topic

I don't know how you can be so certain that the design creates problems. I also am not sure if any of the persons who posted in this thread has the technical competence to evaluate the design only by looking at pictures.

BTW, I'm sure the cars in 1900 seemed just fine to the people of those times.

I guess we all have to live and see how the Goblin will do.
LOL Considering you have no idea what I do for a living or my knowledge of engineering thats a BOLD statement my friend time will tell.

Team MikadoUSA Team Scorpion

PM  EMAIL  GALLERY  Attn:RR  Quote
02-02-2012 06:47 AM  6 years agoPost 38
3Dmuse

rrApprentice

Ontario, Canada

My Posts: All  Forum  Topic

LOL Considering you have no idea what I do for a living or my knowledge of engineering thats a BOLD statement my friend time will tell.
helliaddict2424
Are you an aerospace engineer, specialized in helicopter rotor heads?

PM  EMAIL  Attn:RR  Quote
02-02-2012 07:49 AM  6 years agoPost 39
OnTheSnap

rrApprentice

Santa Clara, Ca

My Posts: All  Forum  Topic

Hey guys,
Taking a step back for a second. At my place of employment we have a few very talented mechanical engineers that I'm lucky enough to interact with on a regular basis. Totally different industry, but we do a lot of mechanical design. In most cases, models are built (we use ProE), and then we're able to run very sophisticated simulations on the stress analysis, movement, metal type, etc.

Going out on a limb here, but if I were designing a 700 class helicopter, I'd probably spring for the $20K software package to run these simulations. Simulating the head to answer the basic questions brought up above are easily answered. Judging by the sophistication of the Goblin mechanical design, they clearly aren't going cheap on the software. I've also done some testing for another heli company and the stress analysis simulations being run on the main gear/motor were brought up several times. Seems like a common practice if you asked me.

Bottom line (IMO) - These guys aren't just making a pretty head. They are blending function and art enabled by some state of the art software.

Anxiously waiting for my Goblin to arrive.

MSH USA -- Cyclone -- Jeti -- Xnova

PM  EMAIL  GALLERY  Attn:RR  Quote
02-02-2012 08:10 AM  6 years agoPost 40
The man

rrVeteran

at home

My Posts: All  Forum  Topic

I agree with hams. Align's DFC recall is exactly because of this issue and their new design doesn't solve it. They will eventually fail because of fatigue.

PM  EMAIL  Attn:RR  Quote
WATCH
 9 pages [ <<    <     1     ( 2 )     3      4     NEXT    >> ] 13728 views POST REPLY
HomeAircraftHelicopter
e-
SAB
Other › No swash driver
 Print TOPIC  Make Suggestion 

 24  Topic Subscribe

Tuesday, August 14 - 4:29 pm - Copyright © 2000-2018 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online