DFC!? Pah! ......

[heathy]

DFC!? Pah! ......

Or the ultimate in low heads

ImageUploadedByTapatalk1364420595.513158.jpg

The Tdr, doesn't get much lower than that.

[tonystevens]

Cheers heathy, shame its electric although id like a go lol!

[heathy]

DFC!? Pah! ......

Tis the future this leccy stuff you know.

[tomatwalden]

Or the ultimate in low heads

[ATTACH]57753[/ATTACH]

The Tdr, doesn't get much lower than that.

Lovely looking machine the TDR! How are you liking yours then?

[heathy]

Lovely looking machine the TDR! How are you liking yours then?

Well, 2 flights in freezing wind so far, loved it. Shall be coming out to play again this weekend. Already got some bling for it

[tomatwalden]

Well, 2 flights in freezing wind so far, loved it. Shall be coming out to play again this weekend. Already got some bling for it

Jolly Bee TDR ?

I've got some decent packs for my Goblin now, and hopefully have got the tail gain sorted. Looking forward to the long weekend to test it! Might have to commit a day to building the 550 though ...

[heathy]

DFC!? Pah! ......

That's what evenings are for! No jolly bee cano for it yet. Soon.

[bolders]

What a load of rubbish. Material selection is down to the designed loads that particular designer has calculated he requires. No bolt whatever is meant to take any shear or bending moment which is what you get with the dfc links, period. A ball link is less likely to shear because of the rotation designed into it funnily enough that's why they're called ball links.

By using a stronger tensile strength bolt align have sort of solved the problem but not eradicated it because the shear is still there unlike a plastic link. Pointless debate over a design flaw, don't understand why people are trying to justify it

Ah come on Dave :P there is nothing wrong with a bolt in shear as long as you don't exceed its shear strength (which admittedly is a bit lower than tensile strength). But ultimately you are applying the same rules as when putting a bolt in tension (ie consideration of the area and the stress limit - whether it be shear or tensile).

The bending will likely lead to higher stress levels but this should be ok as long as material strength is not exceeded.

To me, the main consideration with the Align design is the cyclic loading (which admittedly is probably mainly due to bending and I guess also leads to quite high stresses due to the very rigid design). This implies that the predominant failure mechanism is due to fatigue especially when the high frequency of the loading is considered

btw not stating either way whether this is a good or bad design, just that a bolt is ok in shear as long as it is maintained within material limits.

[waveydavey]

Exactly what I said, design limits

I would argue that shear and tensile are different though and shear strength will always be less, taken that the bolts used were threaded for most of the shank, you know that the threaded portion poses many stress raisers. The new bolt with a much higher tensile strength not only allowed you to tighten to a much higher torque but also they applied a much longer shank which was also housed in the blade grip control arm, reducing the stress to the bolt

[trillian]

One thing I was surprised to hear was that the three blade heads JR team pilots are testing for flybarless F3C and 3D flying have no dampers at all they are totally rigid and yet this seems to work OK as the FBL controller can compensate. (Although I would imagine it is bound to limit how low you can run the headspeed without some kind of wobble unless a side effect of having more than two blades changes this).

The point being, if a DFC head was totally rigid and allowed no teeter than the stresses would only be the drag of the inner swash which I would think are not too great.

[Benjbrit123]

One thing I was surprised to hear was that the three blade heads JR team pilots are testing for flybarless F3C and 3D flying have no dampers at all they are totally rigid and yet this seems to work OK as the FBL controller can compensate. (Although I would imagine it is bound to limit how low you can run the headspeed without some kind of wobble unless a side effect of having more than two blades changes this).

The point being, if a DFC head was totally rigid and allowed no teeter than the stresses would only be the drag of the inner swash which I would think are not too great.

Interesting you say that because my protos has a solid head I took out the dampners and replaced with metal washers so it was totally solid, It fly awesome! I can still run stupidly low rpm and it won't wobble either I will take a video at some point!

Ben

[KevDavies]

eh while I think on Ben. Do u fancy a fly tomorrow?? ill be at the field for 10 if you wanna come over