sneek peek

[growmaster4]

cant wait,get the i2winkies ready

[BobOD]

Twinkies anyone?

[growmaster4]

you have me over here drooling bob,i need my helicrack now,and a twinkie too

[BobOD]

Originally Posted by growmaster4

you have me over here drooling bob,i need my helicrack now,and a twinkie too

It's all ready to go. But, I ate all the twinkies.

It'll go out tomorrow.

And, let me tell you, if you liked my 500, you're going to FREAK.

[growmaster4]

cant wait.but why you gotta eat the twinkies

[OICU812]

Man that looks pretty sharp, in regards to the dampers, what durometer are they?

[BobOD]

What durometer would you like?
The material shown here is 65 durometer but that doesn't really define everything. Stiffness also depends on surface area and pressure applied as well. By altering the shape of the tapered collet as well as the amount of pre-compression applied (with the nuts), I can produce a range of dampening characteristics. Current setup does a good job of dampening higher frequencies while allowing very little give under cyclic loading.
Sorry for the long answer.
Currently, it's set up to "quite stiff" which is what most pilots seem to ask for..and flies quite well to my liking.
But, I'm prepared to experiment to suit personal preferences.

[Borneoben]

Hi Bob

How do you "match" teh stiffness of teh dampers from side to side?

Do you measure teh gap betweeen the head block and the Nut and make sure they are the same both sides?

have you experienced these nuts moving in flight and changing the damping?


Just curious as its a very interesting design

Ben

[BobOD]

I think you are figuring the nuts are adjustable. Not really. They tighten down onto shoulders on the feathering shaft. This centers the feathering shaft. Shims can be used to adjust the pressure applied to the tapered collets to adjust radial compression into the damper rubber.
At launch, it will be fixed to what I have found optimal. But, the idea there is that simple modifications could allow for adjustments so I don't have to tell other people what they would find as optimal.

[Borneoben]

That makes much more sense i can see how it works now.

What are the advantages of doing it this way as opposed to how 99% of other manufactures?

Essentialy the feathing shaft bolts do the same thing right?

Is it to get a more consistant load on the dampers?
Or is it to get a more accurate centering of the feathering shaft?

I know you have done it this way for a good reason i am interested to know what that reason is?

There must be a very good reason as your feathering shaft is allot more complicated and costly to manufacture.

Thanks for sharing your design philosophy with us. I for one take inspiration from you for my amutaure heli design efforts!!

Cheers

Ben

[BobOD]

Right now, most use the grip bearings to press axially into the rubber. This centers things and also puts an axial preload on the bearings and compresses the rubber (well, hopefully it does if all the tolerances add up). It is a convienent way to do it but very limiting. The bearings want a specific axial preload. The rubber wants a certain compression. Change the rubber and maybe there's a different force. They are two completely different requirements so why have them dependant.
My design completely separates one from the other. One has no affect on the other.

Next, current method of applying radial compression to the damper is by the size of the hole through it. But you are limited to the amount of compression because it gets impossible to stuff the feathering shaft through it. Tapered collets take care of this problem. They also provide a way to adjust this compression.

The grip bearings are pressed against some disk springs. This produces the desired axial pre-load to these bearings. Never more...never less. This is how many precision spindles are designed.

I'm giving away all my secrets.

[Borneoben]

Awsome Bob

Thanks for sharing

I love it when a true Enthusiast and Craftsman make parts for enjoyment and improvement against profit.

The end user ends up with a far superior product.

Keep up the GREAT work i love seeing all your products.

Cheers

Ben

[growmaster4]

just received my head today and this thing is beautifullcant wait to give it a good ringing out,looks great on my logo,too bad my esc is with castle getting replacedi may have to pull one from another bird just to get her flying

[BobOD]

No more sneaking.
http://www.rc-tek.com/us_store/i2-rc...ead-p2256.html

[BobOD]

Just finished up another addition to the Logo600 tail.

New idler and metal frame spacer.
Now the sideframes are spaced and held parallel with precision. No flexing the sideframes and the bearings are held parallel and accurately spaced.
Also, the idler is bigger in diameter so it puts less flexural stress on the belt. The stock one does not meet the belt recommended minimum radius of curvature for a back side idler. This one does. This should improve belt wear and tear a bit.
AND, it looks good too.

[BobOD]

Hey Growmaster,
Sorry I've been dragging my feet on your Trex 700 custom work but I got a little side tracked. These plastic bits have just been p!$$ing me off lately so I decided to knock out some grips.


OK, I got the over center issue thing sorted out. There won't be any of that.

Of course we'll match or exceed the pitch range in both directions.

I wonder how people will feel about my adding 2 or 3 grams to the tail? That's mostly from the steel balls (instead of the plastic molded in ones ) so I figure it's pretty well worth a few grams. It'll be able to handle more load too.

I'll knock out your 700 tomorrow. I'll try to ignore that dang pulley at least until after that.

[Inverse]

I hope the head etc performs well for you.

[growmaster4]

no problem bob,i am usualy a pretty impatient guy buy your parts are worth the wait.
by the way,those grips look awesome,will they fit a t600?

[BobOD]

T600...I'll have to get my hands on one of them some day.

[growmaster4]

dont worry,i guess i could test fit all your parts for you until you get one