Main Blade question

[petervdb]

Hi all

Quick question. I have a Hirobo Bell 47G with wooden, semi symetrical blades. Length 79.5cm, chord 6 cm. I would like to replace them with the Vario RH blades (Order 420) which are length 80cm, chord 7.5 cm.

I would appreciate any thoughts you may have on whether these blades would be a good replacement. The Bell is a 24cc petrol engine model. I can't see the length being a problem, and the extra chord would help produce more lift perhaps, but maybe there are other considerations I am not aware of? I think they would be a good match, but would appreciate your views before shelling out on them.

Cheers

Peter

[petervdb]

I don't think it will be a problem so I'll speak to Vario and see what they say. Cheers.

[Helimadlarry]

The only real disadvantage with longer blades is how far they flap when applying cyclic control. The longer the blade the larger the risk of a boom strike due to flapping. Though on a scale model like the Hirobo and with such a subtle difference in blade length it shouldnt be a problem as it won't be subject to high speed cyclic manouveres. Unless of course you enjoy a bit of scale 3D

[trillian]

I also have a Bell 47G with wood blades (they are 800mm). I was going to look into this as well but now I will prob just sell it as it's really too big to be practical right now.

But anyway, it partly depends on if you have the metal head or the newer plastic rotorhead.

I have heard that with the metal head it is intended to have some flex in the blades. With the plastic rotorhead you prob have more options.

[petervdb]

Hi everyone - sorry I have taken so long to report back, but I bit the bullet and got the Vario semi symetrical and it made are real difference the flight characteristics. It is a big improvement on the symetricals that I had. Before you could hear the engine note drop slightly when lifting into the hover, but with the new blades there is no noticable engine note drop. In fact you need to be a little more vigilant on lift off so you are ready for it :-)

[skidmark]

Hi peter,
I have SAB 810s on my Hirobo Bell 47G , they are real good,
Call Motors & Rotors.

Cheers Garry

[pchristy]

Hi peter,
I have SAB 810s on my Hirobo Bell 47G , they are real good,
Call Motors & Rotors.

Cheers Garry

Yes, I've fitted a set of those as well, with good results. Recommended!

[electricsceadu]

i use bbt evolution 795's and nhp800's
both are a good blade to use
but i may look into the vario semi's



and scale 3d inverted engine off auto/crash type landing, mine didn't boom strike
but the boom did bend when it hit teraferma and the blades were unmarked (the blades are now used for sturing paint)

[petervdb]

Hi peter,
I have SAB 810s on my Hirobo Bell 47G , they are real good,
Call Motors & Rotors.

Cheers Garry

Are those semi symetrical or fully symetrical?

[lawrencelkl]

Hi All,

Been quite some time since I posted here. I have done some work on my old hirobo Bell 47G.
all tested OK in UK last December (video as proof!)

but when i brought it back to Malaysia, the hot weather let me have to lean out the engine a bit due to less dense air and hence less power. then it was really stuggling to lift. at some settings, it can lift but no more than that, mroe like bouncing 3 feet of the ground...

I am using the nhp razor pro symmetrical 800mm blades.
I read some posts here and can anyone reconfirm with me that the vario semi symmetrical blades will give more lift than the nhp 800 mm pro blades? also , where can i get a pair , prefereably in the UK?

Thanks,
Lawrence

DSC_0982.jpg

[lawrencelkl]

Video link taken on Jan 2012.

Hirobo Bell 47G Gasser RC helicopter - YouTube

[electricsceadu]

semi's will give more lift but make sure you get them for a right hand rotation head

vario parts can be purchased from john white at
www.vario-helicopter.co.uk

[lawrencelkl]

Vario blades for Bell 47G

semi's will give more lift but make sure you get them for a right hand rotation head

vario parts can be purchased from john white at
www.vario-helicopter.co.uk

Hi, thanks for the reply. Is right hand rotation same as for blades turning clock wise viewed from top? Sorry I am not familiar with the term here.

had a quick look at the web but cannot see semi symmetrical blades at 800 mm...I will send a note and ask.

thanks for the help and info..

regards,
Lawrence

[pchristy]

Is right hand rotation same as for blades turning clock wise viewed from top?

Yes - which is why you have to be a bit careful, because most Varios are left-handed (anti-clock rotation).

I had SABs on mine, which worked very well. I got them from Dave Wilshere at Motors and Rotors. Denis Stretton had a set of NHPs for his, IIRC.

Oh, and in answer to your question on another thread that I've just remembered, yes the longerons are 6mm outside diameter. B&Q do suitable lengths of thick-walled aluminium tube at a good price.

[lawrencelkl]

Hi Pete,

Thanks for the info about the blades and the aluminium tubes.
I am planning to get some of those tubes from B&Q this weekend.

Cheers!

Have a good weekend!

Regards,
Lawrence