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Old 01-27-2013, 09:12 AM   #1
hareedy
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Default Dfc head for stretched trex 700 to 800

What's the advantages of the dfc head over the normal align fbl head
Off course for ap flying
I am using ace one
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Old 01-31-2013, 05:43 PM   #2
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83 views and not a single reply ?
come one guys my question couldnt be that hard or is it ?
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Old 02-03-2013, 01:54 PM   #3
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I'm just building a trex 700 with a stretch kit to 800. But from what I read and this was a couple of posts which made me think that it might not be a good idea is that the dfc head is lower to the frame which when fliying hard 3d has caused a few boom strikes (again just what I have read). From that I would think that putting on 800 blades with a lower mounted head (DFC) would amplify that issue.

Again not speaking from experience just exprtapalating some info (and it is just talk), but would make sense that longer blades have more flex and are more likely to hit the boom if they are close to it. That and if you are using an AP rig you might get a gimbal stike.

but then again AP is not as hard on blade flex as 3D

Hope this helps.


refference:
http://www.rcheliaddict.co.uk/main-d...-dfc-head.html

http://rc.runryder.com/helicopter/t679774p1/

http://www.helifreak.com/showthread.php?t=402206
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Old 02-03-2013, 08:54 PM   #4
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Default No problem...

I am using the 700 DFC head stretched with an 800 tail and blades, and I have not had any issues. You would have to be doing some pretty extreme AP flying to get anywhere near striking the gimbal or tail.
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Old 02-04-2013, 07:36 PM   #5
hareedy
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Quote:
Originally Posted by matthewgow View Post
I am using the 700 DFC head stretched with an 800 tail and blades, and I have not had any issues. You would have to be doing some pretty extreme AP flying to get anywhere near striking the gimbal or tail.
so whats the main difference between the dfc and the normal fbl head in performance ?
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Old 02-04-2013, 07:56 PM   #6
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Default Probably not the best person to answer.

For AP flying I don't think you will notice any difference. I've got a 700 FBL head that I started flying with a GoPro and my new ship is a stretched 800 with the DFC head, a 3X Pro Gimbal and Aceone flight controller, the two machines are very different and hard to compare.

The DFC would be easier to setup and have less moving parts? I think you'd be happy with either of them for AP. Though many are saying they would rather have FlyBar....
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Old 02-05-2013, 08:42 AM   #7
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I'm not a fan of the DFC head design at all. It might work out OK for acrobatics, because you'll be using really hard head dampers anyway. But I would think that softer dampers would be better for AP, and the DFC head, I don't think will work well with soft dampers? I just can't get my head past the geometric problems with the design.

And how is it easier to setup? The only real difference is the missing swash phasing arms. And the swash phasing arms don't require any setup so... ?
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Old 02-05-2013, 07:41 PM   #8
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Default Dfc head for stretched trex 700 to 800

Ok guys thanks for replying
But till now I am using the stock dampeners on the 700e v2 fbl head
So where can I find soft dampeners ?
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Old 02-10-2013, 03:49 PM   #9
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DFC is a bit of a fad in many ways. On Trex helis, the DFC has increased the cyclic rate of the heli but this is probably more to do with the fact that it has allowed the head to be lowered. It's interesting to see that SAB have released a non DFC head for their Goblins which in my mind adds credence to my thoughts on DFC heads.

I have a Compass head on my Fusion 50. Compass were one of the original instigators of the DFC style head as far as I am aware, and it is probably the best instigated DFC design. Anyway, in terms of flight, I noticed no difference in how my Fusion flew with its original 'standard' head v the Compass one (the Compass head did not allow me to lower my head, nor did I want it to). Sure the Compass head is simpler to put together and fix and it adds a certain bling factor but from my experience and from what I can tell, if you are using your heli purely for AP, there is not one difference I can see that the DFC head will make.
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Old 02-10-2013, 08:18 PM   #10
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Default DFC on Trekker

While not AP specific, one of the guys at the field has been doing hard 3D on a Trekker. Soon after putting in a more powerful motor and then the stronger gears when the stock stripped 15 seconds into the first flight, one of the DFC control arms stripped out of the head. You could hear a thwap - thwap - thwap from one of the big 800 blades weather veining as the heli went down. When we examined the head afterwards you could clearly see that the threads in the head where completely stripped out and the bolt holes were warped at the exit points. The guy is now running the 3GX head and says it works a lot better.
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Old 02-11-2013, 09:11 AM   #11
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What head dampers did he have?

This is the type of failure I expect with anything other than very hard dampers. Simply put, the design is "overconstrained". The more the head feathers, the more it will flex those pitch links. The more those links flex, the sooner they fail. It's just a mess of a design.
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Old 02-11-2013, 12:26 PM   #12
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Default Dfc head for stretched trex 700 to 800

Ok so where can I get the soft dampers ?


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Old 02-13-2013, 11:50 AM   #13
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I'm still new to this so correct me if I am wrong but the red dampers/dampeners are a bit softer for the 700 head with a 80 durometer rating instead of the black ones (90 durometer rating)


you can also make your own softer ones using certain orings see
http://rc.runryder.com/helicopter/t550091p1/


Oh just edited this to add an answer to your question. you can get the red ones at most hobby shops they are part number HN7024A Damper Rubber 80

Last edited by StraightUp; 02-13-2013 at 11:52 AM.. Reason: added to post
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Old 02-16-2013, 05:26 PM   #14
hareedy
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Default Dfc head for stretched trex 700 to 800

So the softer the dampers the better for ap ?
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Old 02-23-2013, 09:46 PM   #15
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Yep softer is better, I have even heard that plastic heads or plastic blade grips are better for APas there is more flex/give which helps, don't think you can get plastic grips for a 700 though.
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Old 02-24-2013, 02:02 PM   #16
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I generally don't agree with that idea on engineering principle. I have never flown with plastic parts, but after several years in automotive engineering I learned that it is best if everything is as rigid as possible. Except if you need some flex, then engineer in some flexy parts that flex EXACTLY how you want them to. Don't rely on generally flimsy construction to get you the flex you need, it doesn't work as well.

Consider modern car construction. Super rigid body-shells, with precisely engineered crumple zones for impact absorption. Rigid suspension members, with engineered compliance in the bushings.
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Old 03-01-2013, 02:25 PM   #17
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Rob, you have a very good point, about plastic vs metal. Thanks for pointing that out. I think in my last post I was saying softer is better for the dampeners, and added the plasitc head/blade grip point without giving it too much thought. I do have an align 500e that came with plastic grips and some other plastic head parts, which I am still using with over 100 flights and it flies very smooth but now that I am adding extra weight, I am not sure I would trust them.

The metal ones would be much safer for sure, and by going with softer dampers/dampeners that would help. I also don't think they have any plastic blade grips for 700 size just for that safety reason, but I could be wrong.


There are also other way to reduce vibrations to the cameras, mainly in issolation of the AP gear, interestingly enough looks like a guy came up with a very low tech and simple way to eliminate the jello effect on gopros with some wire between two peices of plastic. For those that haven't seen it http://www.helifreak.com/showthread.php?t=503265

One guy uses plastic grips on his 600e for fpv/ap flights to help smoth vibrations. http://www.fpvpilot.com/Pages/FPV600Helicopter.aspx
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