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Synergy R/C Synergy N9 > New gear ratios for the YS91SR- Latest update - 8:1 gear ratio

Long Nguyen K.

Senior Heliman - Location: SoCal, USA -

After reading and posting in this thread I decided to make a 16T pinion. With 124-tooth maingear I got 7.75 transmission ratio.

I have been running 1900 on the original ratio which is 8.27, therefore the engine rpm is 15713. The engine performs really well with this setup however the rear bearing doesn't last long. I changed mine after first 4 gallons. Other people are running it on 1850 heedspeed (15299 engine rpm) with very successful results but I love a higher headspeed such as 1950...

So with the ratio of 7.75, I'm spotting for 1950 headspeed and the engine rpm would be 15113. I don't know if it will work well. Tomorrow I will give it a try and will let you guys know how it goes...

Right now I'm out of the country and I got 2 samples only. I may get some more this week and I will be back to the U.S on the 21 this month. Please PM me and I'll give them away for trails.

Here are some pictures

===================================================================
== 02-02-08 ==

Test flight on 16T pinion + stock 124T maingear

Right Click --> Save As

Jason Chow Synergy N9 7.75 Gear Ratio

===================================================================
==02-05-08 ==

Although the new 16t pinion provides more power on a YS91SR engine I still see that 7.75 gear ratio is too low and the engine runs hot. I'm afraid that the rear bearing is not going to last long. So a new manigear with higher tooth number needs to be made. Here is my calculation based on 1950 headspeed:

124T / 16T --> 7.75 ratio --> 15112 engine rpm --> has been proven having better power

125T / 16T --> 7.8125 ratio --> 15234 engine rpm

126T / 16T --> 7.875 ratio --> 15356 engine rpm --> This is what I want to try right now.

127T / 16T --> 7.9375 ratio --> 15478 engine rpm --> This is what I want to try right now.

Ok guys, stay tuned!

===========================================================
== 03-31-08 ==

I just got some 128T maingears and 16T pinions in and the 8.0:1 gear ratio is made up. At this ratio the engine will revolve at 15600 rpm to achieve 1950 headspeed.

I have put 2 gallons through this new setup and the result is really successful. I got more torque during hard moves and I got the pop of 1950 headspeed. The engine runs cool and doesn't seem to be loaded up. Here is a video of me flying it:

right click --> save as

http://www.socahc.com/upload/long_s....0gearratio.wmv

One bad thing about these new maingears is that the heli becomes a little bit noisy because of not perfect material choice.

===============================================================
== 04-06-08 ==

creightoncarr's testing video

http://www.runryder.com/helicopter/t422670p1/

Quote

Tried the 8:1 gear ratio this afternoon (thanks Long for the gear and pinion) and I have say that I like it. I was running 1940 on the head and didn't have any problems with the engine bogging. Long, you were right about the gear being noisy. When I watched your video I thought your engine sounded a little lean; after flying with the gear this afternoon, however, I now realize the noise is the drivetrain. I had to run 3.5mm of shims on the engine mounts to get a decent gear mesh. It was a little loose but 3.0mm was just a little too tight. I put six tanks through it today and I'm hoping that the gear wore in just enough that I can remove .5mm on each side now and get a proper mesh. I think that ought to quiet it down some if it works. I have video from one of the flight that I will post later after it finishes encoding. Thanks again.

===============================================================
== 04-10-08 ==

My latest testing video on 8.0:1 gear ratio

Right Click --> download

http://www.socahc.com/upload/longng...1_gearratio.wmv

Long Nguyen
Heading back to my country! Gonna have my SHAVERS cut rice!

01-14-2008 04:21 PM

HOMEPAGE

hansking12
Senior Heliman
Location: irvine, ca

i'd love to try one

pm'ed you. . .

01-14-2008 04:38 PM

Long Nguyen K.
Senior Heliman
Location: SoCal, USA

the first 2 samples have been given away. If I get more I will let you guys know.

Long Nguyen
Heading back to my country! Gonna have my SHAVERS cut rice!

01-14-2008 04:49 PM

HOMEPAGE

cJ
Senior Heliman
Location: Lakewood CA

pm'd u

Thanks,
cJ

01-15-2008 04:53 AM

Long Nguyen K.
Senior Heliman
Location: SoCal, USA

Successful testing results!

I went flying today with the new 16T pinion. First, I tested hovering for about 1 tank in both normal and 1950 idle up, took the canopy off, the pinion looked solid, no deformation appeared, the engine stayed cool (about 130). Then I stated fly harder with loops and flips for 1 tanks and then hard 3D'd it for 1 tank. I just want to say the new gear ratio really made the heli INSANELY POWERFUL at 1950 headspeed. The engine had no bog and was a little bit hotter at rich setting. tictocs were extremely fast and solid. Climbout was also quicker. The heli just became very very nimble like my old trex 450.

I couldn't fly more because the bevel gears in the tail case melted up due to overheating. I used home made bevel gears and that's why.

Tomorrow I will have more test fly and will put more stress on the pinion to see if it can hold up. I'm very please with the results now and looking forward to testing more.

The engine performance could be decreased because I was using homemade 30% nitro fuel. I cannot get any coolpower 30% here where I am now.

Stay tuned for more results!

Long Nguyen
Heading back to my country! Gonna have my SHAVERS cut rice!

01-15-2008 11:35 AM

HOMEPAGE

tec548
Heliman
Location: Houston, TX

I want one as soon as you get some more!

Joel

01-15-2008 01:59 PM

creightoncarr
Veteran
Location: Missouri City, Texas - USA

Me too. If you get more let me know - I'm tired of waiting.

01-15-2008 02:24 PM

inkspot1967
rrProfessor
Location: cranston ri.

melted bevel gears....omg not good

Vibe50 VBar flybarless 12X Radix ATGv3
Next-D Rave
WENZEL CANOPYS
Flybars are for Pussies.

01-15-2008 02:32 PM

Awamori
Senior Heliman
Location: Now Osan, Korea October back to Kadena, Japan

Will you be able to produce these in amounts that someone like me could purchase one? These pinions seem like the ticket!

01-16-2008 11:40 AM

inkspot1967
rrProfessor
Location: cranston ri.

synergy is coming out with a 16t pinion soon

Vibe50 VBar flybarless 12X Radix ATGv3
Next-D Rave
WENZEL CANOPYS
Flybars are for Pussies.

01-16-2008 11:42 AM

Bart B
Veteran
Location: Synergy alley

Will this help if I want to run a 60 engine size in my heli?

01-16-2008 03:06 PM

tec548
Heliman
Location: Houston, TX

It's actually the opposite of what you would want. A .60 has a higher power band (rpm) than the YS90SR so you would actually want a smaller pinion to compensate. We are trying to get a pinion that will allow us to run a 1950 head speed within the optimum power band of the SR.

Joel

01-16-2008 03:14 PM

inkspot1967
rrProfessor
Location: cranston ri.

no not good for a 60 engine

Vibe50 VBar flybarless 12X Radix ATGv3
Next-D Rave
WENZEL CANOPYS
Flybars are for Pussies.

01-16-2008 03:15 PM

Bart B
Veteran
Location: Synergy alley

So the stock gearing would suffice?

01-16-2008 03:22 PM

inkspot1967
rrProfessor
Location: cranston ri.

either a bigger main gear or a smaller pinion would be needed

Vibe50 VBar flybarless 12X Radix ATGv3
Next-D Rave
WENZEL CANOPYS
Flybars are for Pussies.

01-16-2008 03:26 PM

Bart B
Veteran
Location: Synergy alley

ok thanks.I'm wanting to build a sport model for training.I buddy box alot of the plankers at the club.I guess I can paint some flowers on it and let the Princess fly it as well

Any excuse to build another Synergy! thx
Long,good luck with your new gear

01-16-2008 03:34 PM

Long Nguyen K.
Senior Heliman
Location: SoCal, USA

I got 4 tanks through the new pinion today. It was really successful. I got more power, the heli was just much quicker than before. Although I noticed there was some small bog when doing fast tictocs it still pulled, pulled and pulled really well.

It was at 1950 heedspeed. I will try 1970 and 2000 tomorrow.

Long Nguyen
Heading back to my country! Gonna have my SHAVERS cut rice!

01-17-2008 10:39 AM

HOMEPAGE

Chuckie
Key Veteran
Location: Crofton Maryland, MHA member

Please try 1900 or 1925 as well.

Charles

Please stand by for faster service!

01-17-2008 04:02 PM

Long Nguyen K.
Senior Heliman
Location: SoCal, USA

I noticed major bog when running 2000 and 2050 head speed. Currently, It has been working very well on 1950...I will test 1850, 1900 within this week...

Long Nguyen
Heading back to my country! Gonna have my SHAVERS cut rice!

01-22-2008 08:13 PM

HOMEPAGE

pwood
Key Veteran
Location: Dubai, UAE

Hi guys

I used to use 7.75 on a X-Cell Tempest FAI and a Freya EX2. Both were for FAI flying. The X-Cell had an OS C Spec and the Freya had an YS ST.

I do realise that the RS has MUCH more torque, but i found the 7.75 not good. It was great to get all the head speed, but if you did bog it down, it took too long to recover. For FAI flying, you could get long run-ins and if you flew 'nicely' you could pull off huge manouvers. But if you overcontroled just a littlebit, it was all over. I changed my Freya to 7,92 and it was much better.

Don't know how much relavance there is with this to an SR.....

Regards
Paul

01-23-2008 06:46 AM

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Synergy R/C Synergy N9 > New gear ratios for the YS91SR- Latest update - 8:1 gear ratio

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