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HIROBO X-spec - Freya - Sceadu - Shuttle > Freya 8.45 w\ YS91 SR Question
 
 
WhirlyBird500
Senior Heliman
Location: Rhode Island, USA

OK got the chance to start the setup of my Freya with the YS 91 SR. So I have a radio and head speed question. I am shooting for 1750 RPM head speed, seem to be a good speed from searches here to use with the YS and 8.45 gearing. So is this a good speed or should it be slightly higher. Next question. For 1750 in my 7C I only need 40% at zero pitch at mid stick. I know the manual says 65% but it also lists a 7.9 gear ratio. For the YS this would work out to be around 1900 RPM for an engine speed of 15000 rpm. Does this sound correct.
04-19-2008 06:35 PM
 
 
pcmpete
Senior Heliman
Location: Palmdale California via Ireland

1750rpm is a good starting headspeed. For 3D 1850-1900rpm is better.
Last year the winner of the 3D Masters was running headspeeds from 1350rpm up to 1850rpm in his routines.
Hope this helps

Pete B

TEAM BEAM
HiroboWorld forum
04-21-2008 06:42 PM
HOMEPAGE  
 
 
rccaw
Senior Heliman
Location: La Palma, Calif.

1750 is a little low for 3D, like pcmpete sait 1850~1900 is better depending on your flying style. I personally fly my X-spec on 1950 and it rocks. I've used the 7.92 before and it worked fine for me but after switching to 8.45 I was getting more torque and it's a good thing.

You're right about the 1900 head speed (1893 to be exact)on 7.92 gear ratio. Don't worry about your radio setting as long as you're getting your target head speed you're ok.

Are you using a governor? If so, just make sure your engine is tuned right, set your head speed and enjoy.

Hope this helps.
04-24-2008 05:47 PM
 
 
WhirlyBird500
Senior Heliman
Location: Rhode Island, USA

Thanks guys. I tend to run my head speed low. I fly more FAI than 3D. I know the engine needs more time on it. Still had a little kick in the tail every so often, still rich.
04-24-2008 06:12 PM
 
 
rccaw
Senior Heliman
Location: La Palma, Calif.

edited
04-24-2008 07:05 PM
 
 
CitationX
Senior Heliman
Location: Danville, IN

ANOTHER YS91-SR GEAR RATIO QUESTION

I too prefer to fly a lower headspeed (FAI-style I suppose) just as WhirlyBird500 mentioned. However, I have a 7.91 gear ratio in my Freya. Typically, the YS91 (either ST or SR) prefer 8.45 but I don't need the high head speed for 3D purposes since I don't (and can't for that matter) fly 3D. Question is, will 7.91 suffice for a YS91-SR engine in a Freya? I realize this may be a personal preference type question.

Thanks guys
05-16-2008 03:25 AM
 
 
F3CWNB
Senior Heliman
Location: Napier, New Zealand

I thought the YS engines were happy with a high ratio (low number) my Freya has the 12/93 gearing = 7.75, seems OK to me...

'Life' is Looking Up!!!
05-16-2008 07:18 AM
 
 
CitationX
Senior Heliman
Location: Danville, IN

F3CWNB - I believe you are correct. My Stratus is set up for FAI and it does in fact run a 7.75:1 ratio just as you described. Maybe that is the way to go on my Freya as well.
05-16-2008 11:34 AM
 
 
Dr.Ben
Elite Veteran
Location: Richmond, VA, USA

Don't forget you have the option on the new 91 tooth maingear to yield 8.27:1 . 8.45 tends to put the SR a bit out of its optimum power band (in contrast to the YSST 91).

Ben Minor
05-16-2008 02:01 PM
 
 
Royrex
Senior Heliman
Location: TN USA

Don't you have to adjust the gear mesh when using the 11 tooth
pinion and 91 tooth main gear?
Arent the gears smaller than the 95 main and 12 pinion?
05-18-2008 01:33 AM
 
 
tadawson
Key Veteran
Location: Lewisville, TX

Nope. There is no provision for any adjustment for any gear pairing on the Freya be it 10, 11, or 12T pinion, and 91, 93 or 95T mains . . . they mfg. them the same diameters, and they just fit . . .

- Tim
05-18-2008 03:00 AM
 
 
Dr.Ben
Elite Veteran
Location: Richmond, VA, USA

Hirobo fiddles with the size of each tooth on the various maingears to make the meshes work. The same applies for they way the pull off being able to swap 11 and 12 t pinions in and out. Ironic and surpising to those not familiar with the models, the mesh works out well in all of the options. It's just plain cool.

Ben Minor
05-18-2008 06:54 PM
 
 
Altrex
Senior Heliman
Location: West Bend, WI

maybe i should be sleeping

i thought that the lower the ratio number, the higher the headspeed for a set rpm. so what is recommended for 3D with a YS 91ST?
05-25-2008 08:00 AM
 
 
helicopterMark
Veteran
Location: Rumson, NJ

YS91SR in a Freya
I have available the following gear ratio's
8.45 - 1821 at 15,400rpm
7.92 - 1945 at 15,400rpm
7.75 - 2030 at 15,400rpm

7.75 is clearly pushing it, however between the other two options which would be desireable?

EDIT - looks like I should be able to procure a 91T maingear for a 8.27 gear ratio and 1861rpm, that seems like the best way to go until something between 7.92 and 8.27 is made available.

M3

Mark Schneider
Team MRC/Hirobo
Evo 90, EVO 50 EX
06-02-2008 06:50 PM
HOMEPAGE  
 
 
Royrex
Senior Heliman
Location: TN USA

I installed on my Xspec the 11 tooth and 91 tooth that Dr. Ben mentioned.
Does not seem too hard on the old OS91 governed.
1500rpm, 1750 and 1900.
Roy
06-03-2008 04:24 AM
 
 
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HIROBO X-spec - Freya - Sceadu - Shuttle > Freya 8.45 w\ YS91 SR Question
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