Rotor design in progress ...

[Rotor Rooter]

HeliDev,

The coordinates for the VR-7 and the VR-7b airfoils have been e-mailed to you.

Here's more information on the VR-7;
OTHER: Aerodynamics - Airfoil - VR-7 & VR-7b
SynchroLite ~ Rotor - Blade - VR-7b - Composite

Dave

 

[Victor Duarte]

christian, i used TRacfoil to generate the points, but in DXF, there are a LOT of points, so i created a spline with only 6 points that fit exactly the airfoil.
i think dave has THE right document. better trust him.

christian , about lead lag, it doesnt work the same way in a powered or in a tip jet,
dave must correct me but there is always a drag on the advancing blade, even at the zero-lift pitch angle.
in fact , my thought is to eliminate the more, but keep the less to be suitable for other uses..
i have an alternative design : a silent block in the housing at the "Y" of the blade, but his way, the pitch axis is defined by the hub, and on my mind, the pitch axix must always follow the blade long axis..

anyway, dig it christian, critisize, i try ti defend what iv done, but believe me every comment makes me wonder, and what you say about lead lag makes me dig again the XV1 docs...

thank you for participating

 

[Helidev II]

I could be waaaaaaaaaaaaay off here, so dont take this as gospel. I havent had a chance to work this out yet, its more musings off first principals.
The lead/lag hinge is required not because of the way in which the rotors are powered, but because of seconadary forces associated with flapping.
I personally dont see how a tip powered rotor would differ from a hub powered rotor in this aspect. If this were the case then an autogyro wouldnt require an underslung rotor, or lead/lag hinges on rotors with >2 blades.

A tip jet rotor blade will need to be stronger in the in the root and in the fore/aft axis of the blade anyway due to the tip jet having a greater arm on the root. Assuming all this to be true, then I think its more than feesable to design out the lead/lag hinge as was done on the XV1 120.

The lead lag hinge has claimed amny helos over the years from ground resonance. The 500's lead lag dampers have to be within 5% of design spec to be airworthy. Personally I think that dooing away with it would be a good idea especially since you are trying to design a low cost helo. Its cheaper to add a bit of weight, sacrfice a little performance, than add an extra moving part. I think this is especially true for a light helo, where you dont have to find any extra strength unobtainium to make the design work.
Im not sure what you mean about the "silent block"

R^2, thanx for the coords on the VR 7.

 

[Rotor Rooter]

Victor,

A thread describing a new style of rotorhub has been started. Theoretically, it should be more effective operationally then any existing rotorhub, yet it's design is so simple. It will also be economical to build. This rotorhub should be ideal for your requirement.

It would have been posted earlier but I was troubled about whether to build it then post it, or post it then build it. I don't want anyone patenting this invention.

Dave J

 

[Victor Duarte]

dave, i checked the new thread.. well here s a trick some musicians use to prove the peternity of their songs : send your self a letter, with Receipt, and dont open it, then you can further prove it was your idea.
cheers

christian, i study a little more your comments and still making some drafts..
by silend block i mean dampers , sorry for the translation.
cheers