DFC!? Pah! ......

[tomatwalden]

I make no bones about the fact I'm dubious of DFC designs. I do understand that they lower the rotor disc, making cyclic response more crisp.

But, look at this picture of my Align 500efl pro rotor head next to the goblin 500 hps rotor head.

Look at the difference in distance between the blade grips and swash plate ( both with swash driver arms at 90). You don't need DFC to lower the rotor disc, you just need a good head design!

ImageUploadedByTapatalk1361439380.624293.jpg

[jimmyhorns]

I always like getting a good head design

[Stu girdler]

Am I missing something? The distance between swash and grips does not reduce actual head height.

regards
stuart

[BenScoobert]

This low head stuff is old news
LowRider.jpg

[trexamanic]

i would of thought the goblin had a far more responsive cyclic due to the short linkages. It certainly looks a better design.

[tomatwalden]

Am I missing something? The distance between swash and grips does not reduce actual head height.

regards
stuart

The photo is possibly unhelpful... I was just comparing the two and noted the better design of the Goblin. In this case, the shaft looks similar, but in reality, the Goblin is a bigger machine overall (swinging 500mm blades) than the Trex (swinging 425 blades). Scaled down, the Goblin would have a lower head.

I just think it's a good demonstration that Align don't need DFC to lower their heads. Personally, I'm just guessing that their current non-DFC heads are the size they are because they share some parts (eg. main shaft) with a flybarred head. (OK, I really am guessing here! )

[Benjbrit123]

This may be true that you can have the head lower using links and wash out, However It will never be quite as low as a dfc. Plus the Dfc is a very rigid design and there is only one week point which is the bolt going into the grips, However with the new align bolts its not something you have to worry about, I plan on changing the ones in my 700DFC at the end of the year just like you do with ball links, Just keep an eye on them I have to admit that goblin head is very very nice! But my 700 DFC flys amazingly well and its almost the same price as the 500 goblin is rtf forgetting packs... :S

I would be interested in knowing what other problem you know of about the Dfc just for me to keep an eye on, but I love the feel of the head and would never change it out unless align find some huge leap forward in some new design!

Ben

[steve_b]

Personally, I'm just guessing that their current non-DFC heads are the size they are because they share some parts (eg. main shaft) with a flybarred head. (OK, I really am guessing here! )

I think there may be more than a grain of truth to this

[Varelco]

Nowt wrong with the DFC heads, lots of speculation and questioning of its integrity, but never any evidence.

[tomatwalden]

Nowt wrong with the DFC heads, lots of speculation and questioning of its integrity, but never any evidence.

If you're implying that I'm working from home, bored on conference calls and preferred to start an online debate of DFC or not to pass the time, I couldn't comment ...

More interesting than listening about Linux clustering ...

[SaneAdam]

If you're implying that I'm working from home, bored on conference calls and preferred to start an online debate of DFC or not to pass the time, I couldn't comment ...

More interesting than listening about Linux clustering ...

Interesting you say that Tom.... My Mrs is on the very same conference calls regarding linux and other such terms that i have no understanding of . Who do you work for if you don't mind me asking? (Sorry to hijack your thread... feel free to pm if you would prefer) She works from home too constantly on conference calls

[sp4rky-m4rky]

From your image it looks like all the height on the align is just from the main head blocks extra length. Having more engagement here between the block and the main shaft can only be a good thing though. The lowest head height is always going to be determined by the distance from the head to the boom, too low and you will get boom strikes. Once this distance is established then its about reducing complexity and increasing effectiveness of the swash linkage. The DFC does this by removing the anti-rotational arms and by swapping a set off ball links for bearings. The only potential negative is that hard (solid) dampeners have to be used, this can also be seen as a positive too however. I cant fault the DFC head and it feels nice to me.

[tomatwalden]

Interesting you say that Tom.... My Mrs is on the very same conference calls regarding linux and other such terms that i have no understanding of . Who do you work for if you don't mind me asking? (Sorry to hijack your thread... feel free to pm if you would prefer) She works from home too constantly on conference calls

I don't mind admittingly publically that I work for Virgin Media I'm an IT infrastructure architect.

[tomatwalden]

From your image it looks like all the height on the align is just from the main head blocks extra length. Having more engagement here between the block and the main shaft can only be a good thing though. The lowest head height is always going to be determined by the distance from the head to the boom, too low and you will get boom strikes. Once this distance is established then its about reducing complexity and increasing effectiveness of the swash linkage. The DFC does this by removing the anti-rotational arms and by swapping a set off ball links for bearings. The only potential negative is that hard (solid) dampeners have to be used, this can also be seen as a positive too however. I cant fault the DFC head and it feels nice to me.

You've kind of hit the nail on the head of my thoughts. You're spot on about the distance to the boom being the limiting factor. The question of then how you bring the head down to minimise that distance and maximise response is the bit I'm dubious of. DFC achieves it by making the swash links dual-purpose. That is, they transmit cylic pitch to the blade grips and keep the swash in phase - hence the beefy swash links.

I've always thought (and I accept my thoughts are probably dodgy at best!) that the swash driver is designed for the purpose of keeping the swash in phase. It's always struck me that it should be possible to keep it (and reduce strain on the cyclic rods) whilst still lowering the head.

Bottom line is I guess, neither is probably wrong or right - just different. It was having the Trex and Goblin side by side in front of me that got me thinking about all this. As I say - if nothing else, it's an entertaining discussion!

[Baldie]

DFC!? Pah! ......

Wonder if the HPS head can / will work on other helis? ie the 700 on a trex 700? Think they both have 12mm shafts