RunRyder - new gear ratio for OS

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Blitz Helicopters Avro 90 > new gear ratio for OS

John Benario
Senior Heliman
Location: Atlanta

The standard Blitz kit comes with an 8.06 gear ratio which Neal at Blitz tells me works very well for the YS, however it is a bit low for the OS. Neal now has a 43 tooth pulley which produces 8.25 for the OS. I anxiously await mine. With the 8.25 ratio the Avro's performance with the OS should be unbeatable.

John Benario

04-14-2008 01:57 PM

kirk
Veteran
Location: Thornton, Colorado

I thought the standard ratio was 8.04:1? I am running that ratio right now on a YS91 and it is running really good and has a lot of power. Not to mention it's very smooth.

We did have one running the 8.04:1 ratio on the OS motor and I think the motor would be happier at the 8.25:1 ratio mentioned. The pulley is less than $20 bucks so making the change should be easy and reasonable cost wise...

Kirk

04-14-2008 02:31 PM

AreA51tje
Senior Heliman
Location: Murcia, Spain

Hi John, Kirk, i have read that this also counts for the YS91SR engine which I have in my AVRO's. Should it be wise to think about this setup?

What are the advantages??
Regards,
Dave

04-14-2008 11:09 PM

HOMEPAGE

kirk
Veteran
Location: Thornton, Colorado

Could not hurt much to try it. As soon as we get some of the pulleys in stock I am going to try it with my YS91SR.

I will have to drop the headspeed a little bit (currently running 1900 to get the YS91 SR in its powerband) but that should not be a big deal. I did a 3D type flight with mine yesterday at a headspeed of 1800 and the heli felt great so the headspeed drop of 100 RPM or so should not make a big difference in the way the heli flys. With the lower ratio I might be able to up my pitch a degree.

I like the heli the way it is right now but its always fun to try something different... BTW the best sounding 91SR I have ever heard was running at 8.27

Kirk

04-15-2008 05:12 AM

John Benario
Senior Heliman
Location: Atlanta

I have been running my Avro at 2000 RPM to get the OS at 16000, similar to 1940 with the 8.25, and I think the OS is happier with the 8.25. I am using my former Synergy as a comparison on the engine happiness. The two helicopters have similar fans and siimilar shrouds so the only difference is the ratio.

THe YS folks flying Synergys and Raptors would be the ones to ask about 8.25 with the YS.

John Benario

04-15-2008 05:50 PM

Alder
Senior Heliman
Location: Birmingham UK

Is the pulley avaliable to buy if so do you have the part number

04-16-2008 12:09 PM

Saleh
Veteran
Location: Kuwait

I have recived mine yesterday which was shipped from blitz on monday
woow great service FEDEX

If you aint crashing you aint flyin

04-24-2008 09:55 AM

HOMEPAGE

marked23
Key Veteran
Location: Lynnwood, WA

Is it just a pulley? Or will we need a pulley and something else, like a different belt?

-Mark

04-24-2008 03:32 PM

Saleh
Veteran
Location: Kuwait

its a pully with a new engine mount

If you aint crashing you aint flyin

04-24-2008 04:19 PM

HOMEPAGE

John Benario
Senior Heliman
Location: Atlanta

I have flown the new pulley now and the OS is much happier with the 8.23 ratio. 1940 on the head and perfectly smooth.

John Benario

04-24-2008 10:59 PM

marked23
Key Veteran
Location: Lynnwood, WA

So I'm curious about how the Avro ended up being designed with the low gear ratio. Was it designed for some other engine?

Will this other gear size be substituted into regular kits?

I bought the SB-18 so that my OS would be hapy running a little faster than usual, so I might just stick with the stock ratio for now.

-Mark

04-25-2008 05:42 PM

Saleh
Veteran
Location: Kuwait

It was a mistake in calculation in the first patch

If you aint crashing you aint flyin

04-25-2008 07:07 PM

HOMEPAGE

John Benario
Senior Heliman
Location: Atlanta

I have communicated at length with Neal on the gear ratio and other items. Neal told me that the 8.0 works very well with the YS long stroke for non-hard core 3D. The American market is 3D oriented, and perhaps in England the YS is dominant (that is speculation on my part, not fact) so perhaps there was less thought given to the OS at first.

In any event, given the news from Kirk that the kits will include both ratios, FAI types can use the lower ratio, and 3D types can use the higher ratio.

John Benario

04-25-2008 07:14 PM

marked23
Key Veteran
Location: Lynnwood, WA

Hmm.. the YS-ST4 is known for enjoying a higher ratio like 8.45. So it's interesting to hear that the YS long-stroke likes a lower ratio than even the os91.

Will the folks in Colorado have the pully and engine mount soon? I don't see it listed on their web site.

04-25-2008 07:39 PM

RyanW
Veteran
Location: Stillwater, Oklahoma

This is very interesting. I flew the Synergy from day one and most of us wanted the 8.0:1 gear ratio. Now you are seeing guys make custom gearing just to have the ratio close to 8:1.

At 8.27:0 the YS ran too high of rpm when you were over 1875 rpm on the head. For those of us who ran a head speed of 1950, you risked burning up the engine because it was running in excess of 16k. I wouldn't recommend running the YS much over 15,600 rpm.

The best I have ever had the YS run was between 15,200 and 15,550.

Unless this machine "processes" the power differently, Blitz nailed it from the get-go with the 8.04:1 gear ratio.

-Ryan

04-25-2008 08:18 PM

HOMEPAGE

kirk
Veteran
Location: Thornton, Colorado

marked23

Yes the pulleys and mounts will be availble soon (shipped as early as next week). As soon as I have cost info the part will be added to the website...

Thanks!!
Kirk

04-25-2008 08:48 PM

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Blitz Helicopters Avro 90 > new gear ratio for OS

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