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Other › No swash driver
03-10-2012 06:08 AM  6 years agoPost 141
rexxigpilot

rrProfessor

Florida

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My fear is that someone will get really hurt, or even killed. Not if, but when this design fails. It is all about fatigue (as has been stated over and over again in this thread). In the ensuing lawsuit all they will have to do is get a mechanical engineer on the stand.
I already did the calculations and the design should last for about ten years of heavy flying. It is almost with certainty that the aircraft will be crashed and the parts replaced far sooner than they will wear out from fatique.

FYI, I'm a civil engineer, but if my license was in mechanical engineering, I would have no problem signing and sealing the design drawings and standing on the witness stand in support of the design. I would bet money that Goblin paid some engineer to run the design through a structural anaylis program. I welcome any mechanical PE to chime in here.

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03-10-2012 07:07 AM  6 years agoPost 142
TomC

rrKey Veteran

Gold Coast, Queensland, Australia

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Rexxy, thanks for your free professional advice in this matter. I'm sure a few people will sleep easier now.

Cheers,
TomC

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

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03-10-2012 07:56 AM  6 years agoPost 143
BobOD

rrElite Veteran

New York- USA

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I'm thinking someone gave it to a CAD operator and told them to get rid of the ugly delrin rods....make it look sexy. But, that's just a total guess on my part.

Team POP Secret

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03-10-2012 01:39 PM  6 years agoPost 144
GMPheli

rrElite Veteran

W. Bridgewater, MA USA

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"I already did the calulations and the design should last for about ten years of heavy flying. It is almost with certainty that the aircraft will be crashed and the parts replaced far sooner than they will wear out from fatique."

I think your calculations are a little off, as the Align head is already failing, and look how robust it is. They are using rigid pieces as dampers in this design. I think you are way off base here. Time will tell!

The other question is why would you design something this way? The design is obviously flawed. And then you have to beef it up to compensate for the bad design? Why not just redesign it properly?

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03-27-2012 06:49 PM  6 years agoPost 145
weru

rrNovice

Miami, FL - USA

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So what's the verdict?

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03-27-2012 09:15 PM  6 years agoPost 146
Jerry K

rrKey Veteran

Houston Area

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Look all over, helis are falling out of the sky!

Time will tell, but not 3 weeks. Either jump and enjoy or give it about a year.

All the Align haters have voiced their opion now just sit back and wait.

I am running it so I do have an interest in the outcome.

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03-27-2012 10:21 PM  6 years agoPost 147
RappyTappy

rrProfessor

Traveling the USA

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If you look at the Goblins design, you can see where they did know that loads are transferred through the link on the blade grip, which is why they use a solid aluminum CNC'd piece to take the side loads instead of a simple hardened bolt. It basically makes the best of the DFC design that is not the most optimal imo. Would make much engineering sense to have a ball link at the blade grip and the rigid hinge point down at the swash.

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03-27-2012 11:55 PM  6 years agoPost 148
Sam2b

rrElite Veteran

Tacoma, WA

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rigid hinge point down at the swash
mmmmm, I doubt that. Think about both elevator and aileron movements on that rigid hinge point on the swash, and the new stress point. In my observations the best is to have ball links on the grip and swash. Align's current swash driver design does this perfectly.

_Sam B_

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03-28-2012 01:14 AM  6 years agoPost 149
Jerry K

rrKey Veteran

Houston Area

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If you look at the Goblins design, you can see where they did know that loads are transferred through the link on the blade grip, which is why they use a solid aluminum CNC'd piece to take the side loads instead of a simple hardened bolt.
I see no difference! If one fails the other will right behind it. Like I say only time will tell. But I am going to enjoy it until they start falling out of the sky.

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03-28-2012 01:47 AM  6 years agoPost 150
Justin Stuart (RIP)

rrMaster

Plano, Texas

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Heliaddict2424 is obviously right with his math, but does it really matter if they make a "perfect" design, or just one that works for 50 to 100 flights until you crash and replace it?

Avant RC
Scorpion Power Systems
Thunder Power RC
Kontronik Drives

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03-28-2012 05:26 AM  6 years agoPost 151
rexxigpilot

rrProfessor

Florida

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Heliaddict2424 is obviously right with his math...
What math Justin? Below is one of Heliaddict2424's previous posts responding to OnTheSnap. He is basing his concern on pure speculation!
If your opinion on the Goblin head is a result of modeling, simulating and testing it, then forgive me for my skepticism.
Not going to lie I did not and I will not take the time to do this. To me and others with machining and engineering backgrounds it simply a flawed design they may or may not rear it ugly head some day.
But, you are correct on the crash part. How many of us can fly 400-800 3D flights without crashing?

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03-28-2012 06:23 AM  6 years agoPost 152
heliaddict2424

rrApprentice

SCV SoCal.

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Pure speculation really ok! I suppose your 300 to 400 flights is based on research and experience lol.. Who wants to fly with a design that was made on how cool it looks and just to be different than every one else that is clearly flawed not me. I flew with a buddy last weekend who is running the DFC head on a Trex 700 he would land after a a minute to check the head and was constantly worried about it I wont mention names but he is a sponsored pilot. And I fly it as well we both agreed it rolls of axis because of the head design but what ever im just speculating LMAO..

Team MikadoUSA Team Scorpion

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03-28-2012 08:03 AM  6 years agoPost 153
rexxigpilot

rrProfessor

Florida

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It's clear to me and most here on Runryder that you like to bash the Goblin without justification due to having some agenda of producing some heli of your own design or some crap like that. Now that makes me LMAO!

And why would anyone extrapolate the flaws in Align's DFC head to the Goblin? The earlier failure of the DFC was limited to the main blade grip arms. The bolts were breaking at the connection point between grip and arm. This was due to having the threaded portion (i.e., the weakest section) of the machine screw at the localized stress point. Haven't you noticed that the grip arm assembly on the Goblin is a single, integral piece? They are not the same as the Align!

If you don't like the Goblin, that's your prerogative. But please don't spoil the enjoyment for those of us who actually bought the kit and are having a blast with it. It's childish and just not cool dude.

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03-28-2012 08:11 AM  6 years agoPost 154
whiskey

rrVeteran

Richmond,Va. USA

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It is getting old

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03-28-2012 08:56 AM  6 years agoPost 155
TomC

rrKey Veteran

Gold Coast, Queensland, Australia

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I 'speculate' that all these silly DFC look-a-like designs will either be scrapped, or heavily modified (dampners on pitch grip link?) over the next few months.

Over the past few weeks I've built a Goblin and a Henseleit TDR (not mine, for flying buddies). In my opinion the Goblin was a much easier and faster build (by almost twice) but the TRD bits were up a notch on quality, esp. the anodized and CF bits. However, I think that the Goblin maingear looks like it's a bit more robust than the TDR's. I think that SAB have found a good derlin recipe!

I liked the TDR pitch link setup better since it has a ball link on both ends and a hinged guide in place of the swash driver. Still, would prefer a proper adjustable swash driver myself.

I'd also like to see the next version of the Goblin scrap the motor belt drive and go with a TDR-like gear drive (with 3rd motor bearing support). Higher eff's and longer motor beariing life imho (just speculating).

Replacing the hard-to-make Goblin tail boom with a less expensive large round dia. boom (like the Diablo), either Al or CF (still could be painted!), together with a proper automatic (hydraulic?) belt tensioner would be nice too. Might end up being 'almost' as good as a TT tail (hint-hint), lol!

A F3C flybarred version of the 700 Goblin would be nice too. I'd rather have one of these than a silly, heavy 630 fbl Goblin that needs 2500 hs to get off the ground, hee-hee!

While the current SAB 700 Goblin is likely to have a few teething pains, it certainly has a lot of very good design concepts that hopefully will mature in time and may form the basis of many model heli designs in the near future. Overall, great work SAB.

Cheers,
TomC

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

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03-28-2012 09:06 AM  6 years agoPost 156
RappyTappy

rrProfessor

Traveling the USA

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So Tom, you just want to see the Goblin turn into the Diabolo, lol

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03-28-2012 09:08 AM  6 years agoPost 157
TomC

rrKey Veteran

Gold Coast, Queensland, Australia

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No, just a better heli! Sure it will eventually.

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03-28-2012 02:51 PM  6 years agoPost 158
heliaddict2424

rrApprentice

SCV SoCal.

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Ok I admit I hsve done my share of bashing. That beeing said I have said I like the looks of the Goblin and if they work out these issues I may own one some day. Sorry I dont mean to spoil anyones fun just trying to point out the design issues. The fact is most people wont notice the rolling of axis issue but the failing of the head does worry me. Enough said enjoy guys...

Team MikadoUSA Team Scorpion

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03-28-2012 05:17 PM  6 years agoPost 159
Santiago P

rrProfessor

South West, Ohio

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I like the ugly green thing too, but cannot get pass the head control link. maybe it will "evolve" into a more robust creature like a Gremlin. LOL
So Tom, you just want to see the Goblin turn into the Diabolo, lol
LOL,
If you like the Diabolo, then go that route, I love mine through and through, but I would not want the Goblin to loose the uniqueness of its tail. No need to copy one into the other.

The main difference between the two is that one is already a pseudo large heli at 750mm blades and can be flown from low to rpm without being restricted by the head dampening. The Goblin you either set to hard rock damping for hard 3d and live with low speed mast bumping "wobble", or go softer which SAB does not seem to recommend to fly conservatively.

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03-30-2012 03:57 AM  6 years agoPost 160
GMPheli

rrElite Veteran

W. Bridgewater, MA USA

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I really don't think softening the damping on this head design will do much to the flight characteristics as the rigid links are pretty much over riding the dampers. This is because the links would have to bend in order to allow damping.

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