maximum blade length for stretch?

[wangotaco]

I am creating a stretch. It has a 700 tail, rc-tek head, and I currently have
it fitted with edge 710 blades. The main blade is drooping down (not tight, and 14mm slot with a 12mm blade), but, you can see how close the tail and blade gets...should I worry about that? maybe get a 700 or 690? Is there an actual rule of thumb for calculating the
blade length?

---greg

[helihaven]

I like to keep a good inch (25mm) between my main blade tips and my tail blades..just my rule of thumb...in that second pic they sure look mighty close!

[nwmartin]

I have a stretch 600 with 615 blades 700mm not good for 600 heli

[wangotaco]

Hi,

I don't understand your comment. I used to have 600 blades, I increased the tail boom to a 700 size boom, Why not 700 blades?

-g

Originally Posted by nwmartin

I have a stretch 600 with 615 blades 700mm not good for 600 heli

[Superior]

I fly on 693 edge blades

[helihaven]

no reason at all i can see not to run 700's on her...you can always run a bit smaller tail blades...that triblade set up on the tail will make up for it!

[Luvmyhelis]

I agree fully! Helihaven is right. Mine is slated to run 720s. The only reason they are this short is the limitation of my grips, and my wallett. And you need at least an inch to allow for the main blade compression wave between it and the tail blades or you will run into trouble. Nighflyr just completed a 600 with a 900mm stretch and a 1000 in the works. No reason to keep a stretch short unless your supporting equipment will not allow for it.
And calculating blade length is measuring from your grip holes out to as far as you want to stretch your boom and belt/tt, and again leave breathing room for your tail.

[nightflyr]

Originally Posted by wangotaco

I am creating a stretch. It has a 700 tail, rc-tek head, and I currently have
it fitted with edge 710 blades. The main blade is drooping down (not tight, and 14mm slot with a 12mm blade), but, you can see how close the tail and blade gets...should I worry about that? maybe get a 700 or 690? Is there an actual rule of thumb for calculating the
blade length?

---greg

A word of caution on your build...

In your present configuration you will get the shakes..

Adding a rear cross brace will help eliminate the issue..




I had also purchased a second set of lower frames and laminated them to the orignals in order to make the assembly extremely rigid.

I also removed the front plastic tray and used frame spacers to help with the rigidity...




The setup can now handle up to 1100mm main blades

[wangotaco]

I was wondering about the rigidity of the frame. The g10 material is flimsy, and there is a big gap there. The re-enforcement looks like a good idea. I was also thinking about running the boom braces from the top, but, I don't think there is enough room. The k-frame is extremely rigid for the servos, head, tail boom. The issue is the tail boom triangulation? My goals were to have a modest stretch out of this; mainly I just want direct swash. If necessary I'll drop back to the 600 size that it was designed for. Does anybody have experience with the k-frame on a 600 class heli, sport flying and trivial 3d? Thanks for the tips, I could have shook this apart on the first flight :-(

[nightflyr]

Don't misunderstand ..
The shakes won't damage the helicopter.
The lower frame set is fine and does just what it was meant to by design for a 600 class....

But when you decide to stretch out to 700, 800, 900 or 1000 You need to address items that were never intended by the 600 design.

[wangotaco]

No misunderstanding. It is what it is. There is a bit more movement with this
frame design as compared to my other 600s (600 e pro, 600efl). However, the top
of this frame is much more rigid than the aforementioned frames.
I don't think there will be
any adverse side effects. I am glad you pointed it out, I was going to mount the
sk720 fbl controller on the base plate. However, I think I will move that to the top
frame to eliminate the input from the flexing frame.

---greg

Originally Posted by nightflyr

Don't misunderstand ..
The shakes won't damage the helicopter.
The lower frame set is fine and does just what it was meant to by design for a 600 class....

But when you decide to stretch out to 700, 800, 900 or 1000 You need to address items that were never intended by the 600 design.

[Luvmyhelis]

Great idea, I am using the Sk720 on mine also. Having it in a more vibe friendly spot can only help. Especially if you ever plan on using the SL bailout feature. What a fantastic controller, I love the two I have and am planning a third. Plus, as soon as I can afford a new Rc-Tek head I am stretching out quite a bit farther.

[skray775]

I am going to make up a nice X brace for you guys stretching the heli's.

Was going to cut an aluminum anti rotation plate for G today but last night about midnight I was fitting my final part to the new CNC mill and did not notice the motor for the X axis was going to hit. I crunched the encoder on the end of the motor

I then stayed up and redesigned the part (front way cover) and it was 3 am before I finished.

[wangotaco]

Kelly,

Looking forward to it!

Do you have any pics?

-g

[skray775]

I had a thought... you should have spare frame spacers from the kit. the round aluminum dowel that is threaded on each end. If I add holes to the rear of the lower frame set it would be simple to screw one of them between the lower frame set. I am betting that would stiffen up that section without a x brace.

And I agree I would keep the gyro higher on the aluminum frame. I mounted my Beast X on the tail case but you have a different tail case then the stock one with the flat spot on it.

I am thinking of a revision with a space for the tail servo and a plate for the gyro.