717 blades on a 700 Carbon

[crazy_for_flying]

Hey guys. So I've seen a video of a fellow helifreaker fly his Goblin 700c with vtx 717's on them with good results. Goblin recommend not to pass 710mm but he seemed to have good luck with that. You think I'd be ok running mine with them long term. My goblins currently set up as a kse so if I put a two blade head on it I'd keep the three blade tail with 115's and want to run the vtx but I wanna know if it would be same in the first place.

[HeliSoCal]

I flew a set of vtx 717 on my blackthunder 700

[seefest]

It might be a case of how you fly. They might be ok if flying sport or soft 3D, but if you stick bang smack.......not so much. Easy enough to measure the clearance of your existing blades.

[jchbarnes]

I have had the vtx 717 on my 700C for quite a while now with no issues...

[Smoggie]

It depends on what tail blades you run but with 115mm tails the biggest mains you can run without risk of main and tail blades clashing is 710mm, this leaves only a few mm clearance.

Sure you can fly it with bigger blades but the risk of blade to blade strike is there. 99 time out of a 100 flights you will be ok but it's still not worth the risk IMHO.

[crazy_for_flying]

Originally Posted by Grumpy_Old_Man

It depends on what tail blades you run but with 115mm tails the biggest mains you can run without risk of main and tail blades clashing is 710mm, this leaves only a few mm clearance.

Sure you can fly it with bigger blades but the risk of blade to blade strike is there. 99 time out of a 100 flights you will be ok but it's still not worth the risk IMHO.

I have a three blade tail so I could put some 105 (or the new vtx 107 ) and it sacrifice anything. That would give me 10ish mm more from the mains blades.

[Smoggie]

Originally Posted by crazy_for_flying

I have a three blade tail so I could put some 105 (or the new vtx 107 ) and it sacrifice anything. That would give me 10ish mm more from the mains blades.

Yep, that's a good plan!

[Luvmyhelis]

Still have a guy running 720s on his original Gob 700, (my old original carbon green one). I ran 720s for quite a few years with four different manufacturers. Three different Gob 700s with four different heads. Zero blade strikes. 115s on the tail.

Your luck may be different?

[Smoggie]

Originally Posted by Luvmyhelis

Still have a guy running 720s on his original Gob 700, (my old original carbon green one). I ran 720s for quite a few years with four different manufacturers. Three different Gob 700s with four different heads. Zero blade strikes. 115s on the tail.

Your luck may be different?

Depends on many factors, not least how hard you fly and the RPM you run. The main blades have to lead or lag a lot in the grips and that has to be combined with big pitch input to get the main blades to swing down far enough, and then the two sets of blades need to be as just the worst point in their rotation. So it's going to be a rare event, but it's certainly 'possible' that they will hit each other. SAB dont state limits on blade size for no reason.

It's easy to test on the bench just by manipulating the blades, 720's will touch the tail blades very easily on a bench test. Just because it hasn't happened yet in flight doesnt mean it cant happen. Why take the risk?

[jchbarnes]

Originally Posted by Grumpy_Old_Man

Why take the risk?

Because I like the lower disc loading, lower headspeed required for same agility and longer flight times...

Yes I know one blade strike will quickly change my risk-benefit opinion but I have thrown it around a fair bit, frequent full negative collective punchouts and have so far been 'lucky'..

[rb30cory]

My g700c has had 717s and 116 tails on it for the last 8 months. 196 flights later it's still running strong. I do have the sped up tail pulley which offers a few mms of clearance.

Here is a flight of it at IRCHA last year right after I got them.

[ame="https://youtu.be/FsH3F_ktb6c"]IRCHA 2016 Goblin 700c Flight - Pilot Cory - VTX Blades - YouTube[/ame]

[HeliSoCal]

Kyle has a video of him flying vtx 717 on the BT700. If he can do it I'm sure it won't be a problem.

Sent from my Pixel XL using Tapatalk

[Helimaster1]

Depends what you do. I prefer the SAB 690 tareq on all my machines.

Love the way they fly. No comparison

[Caeguy]

Resurrecting an old thread as I'm looking to put some VTX717 on my Goblin 700C.

I really like the VTX717 on my Protos and want them on my Goblin. I'm currenlty running Rail 116 on the tail and willing to drop to a shorter size. I was thinking of the SAB TB110 tail with the VTX717. Anyone running this combination? This should give me clearance while not compromising the tail performance too much, Thoughts?

[Spencerkey]

On my Sport 700 I’m running VTX 717 with Rail 116 and I have had no issues. In the past I have used Rail 716 w/ Rail 116 with zero issues as well.

[Luvmyhelis]

One thing to consider w longer blades, pull your tail belt tight! Forgot to post that earlier. My tail belt indicator sticks out roughly twice as far as the factory specs suggest. That will buy you room and eliminate belt slop. Got a very good pilot at our field running 720s on his Comp w 115s. (same boom specs) Koz Comp 850 motor and 200a esc. He pushes it hard, blades are also clamped down, and I do mean clamped down. I went with 690s a few seasons back myself, like a more nimble feel. .

[Caeguy]

Mounted the 717's and it looks like I should have good clearance...even when blades are bent(lagging). Whats a good method to double check?

[lucasouthoffrance]

What I do is to measure the distance between main and tail shafts, the main and tail grips distance from shafts axis, finally comiling all that in a simple spread sheet. I can then compute the gap between blades and also evaluate the maximum size of tail/main blades knowing the other one...
For instance, I'm planning for VTX717 and 106 tails, which gives me 7.5mm of clearance.
Also, I see that with VTX717s the maximum tail blade size is 113.5mm. Inversely, with 106 I could go up to 724.5 on mains.

Simple but efficient (for me at least...)

[Caeguy]

Thanks. If I understand this correctly, this approach assumes the main and tail blades are aligned on the same plane...which would be the most conservative approach IMO.

[lucasouthoffrance]

Originally Posted by Caeguy

Thanks. If I understand this correctly, this approach assumes the main and tail blades are aligned on the same plane...which would be the most conservative approach IMO.

Yes, it's the worst case but I prefer to be safe...