*Pitts Style Muffler For OS MAX 120AX*

*Pitts Style Muffler For OS MAX 120AX*
View related threads: (in this forum | in all forums)

Logged in as Guest

Users viewing this topic: none

Printable Version

Saito FA-180 GK
Seller: RCadmin
Details: $375.00 | 8/25/2008 | Classified Ad
We will rotate YOUR AD in this spot if you select "Forum Featured" when placing or editing your ad!

All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Glow Engines >> *Pitts Style Muffler For OS MAX 120AX*

Page: [1] 2 3 4 next > >>

Login

Message

<< Older Topic Newer Topic >>

*Pitts Style Muffler For OS MAX 120AX* - 1/2/2006 6:59:12 PM

Zippi

Posts: 3001
Joined: 6/29/2004
From: Evansville, IN, USA
Status: offline

Does anyone know what Pitts Style muffler will fit the new OS MAX 120 AX? I haven't seen a listing for it anywhere.

_____________________________

"It Ain''t Lookin Good"
http://zippi.50webs.com/index.htm

Post #: 1

RE: *Pitts Style Muffler For OS MAX 120AX* - 1/2/2006 7:48:32 PM

Rcpilot

Posts: 6527
Joined: 3/20/2002
From: Arvada, CO, USA
Status: offline

You buy a 90 degree adaptor and use the factory muffler.

_____________________________

Airplanes have expiration dates. It''s just not printed anywhere on them.
I''m not really an airplane pilot; but I did stay at a Holiday Inn Express last night.

(in reply to Zippi)

Post #: 2

RE: *Pitts Style Muffler For OS MAX 120AX* - 1/2/2006 9:22:05 PM

seanychen

Posts: 2914
Joined: 7/20/2002
From: Canton, MI, USA
Status: offline

The version that comes with muffler also comes with 90 deg adaptor that turns the stock muffler into a Pitts.

_____________________________

E_Total = M*G*H + 1/2 M*V^2
When H=0, all of airplane's velocity becomes crash energy!

(in reply to Rcpilot)

Post #: 3

RE: *Pitts Style Muffler For OS MAX 120AX* - 1/3/2006 4:04:32 PM

Zippi

Posts: 3001
Joined: 6/29/2004
From: Evansville, IN, USA
Status: offline

Thanks guys. Thats what I am planning on doing but started to question myself on if it would fit in the cowl ok. I was just checking on the Pitts style muffler and couldn't find a listing for one.

_____________________________

"It Ain''t Lookin Good"
http://zippi.50webs.com/index.htm

(in reply to seanychen)

Post #: 4

RE: *Pitts Style Muffler For OS MAX 120AX* - 1/3/2006 6:40:22 PM

seanychen

Posts: 2914
Joined: 7/20/2002
From: Canton, MI, USA
Status: offline

The manual gives the dimension of the powerplant envelope when mounted in Pitts configurations. See the last page of the manual:

http://www.os-engines.co.jp/english/line_up/engine/air/aircraft/manual/120ax.pdf

_____________________________

E_Total = M*G*H + 1/2 M*V^2
When H=0, all of airplane's velocity becomes crash energy!

(in reply to Zippi)

Post #: 5

RE: *Pitts Style Muffler For OS MAX 120AX* - 1/4/2006 1:04:53 AM

STG

Posts: 3498
Joined: 7/3/2003
From: New Richmond, WI, USA
Status: offline

Is the stock muffler 8oz with the 90° installed? A good slimline should be 5oz or less.

Has anyone had one of these things fired up yet? My guess is that with a good exhaust system it should be spinning a good 17x6 in the low 9's?

My 108 with Jtec pitts(loud and free) turns 17x6 apc ~9200. This motor has smaller transfer ports and I think a little milder port timing. Should be good for in the 9's though...probably better.

_____________________________

Good Flying to you!
See Blog for RCU Video's

(in reply to seanychen)

Post #: 6

RE: *Pitts Style Muffler For OS MAX 120AX* - 1/4/2006 2:12:50 AM

seanychen

Posts: 2914
Joined: 7/20/2002
From: Canton, MI, USA
Status: offline

I don't think a 17x6 will show the true color of this beast, as the peak HP is developed at 9000 rpm. Something along the line of 17x8 or 18x6 is more like it. But sorry, I haven't fired mine up yet.

My OS 108 w/ Slimeline Pitts will run APC 17x6 @ 9400 rpm. This engine is rated at 3 HP @ 1x000 rpm. So the 120 AX with 3.1 HP @ 9000 rpm should do a little better.

_____________________________

E_Total = M*G*H + 1/2 M*V^2
When H=0, all of airplane's velocity becomes crash energy!

(in reply to STG)

Post #: 7

RE: *Pitts Style Muffler For OS MAX 120AX* - 1/4/2006 3:02:51 AM

STG

Posts: 3498
Joined: 7/3/2003
From: New Richmond, WI, USA
Status: offline

quote:

ORIGINAL: seanychen

I don't think a 17x6 will show the true color of this beast, as the peak HP is developed at 9000 rpm. Something along the line of 17x8 or 18x6 is more like it. But sorry, I haven't fired mine up yet.

My OS 108 w/ Slimeline Pitts will run APC 17x6 @ 9400 rpm. This engine is rated at 3 HP @ 1x000 rpm. So the 120 AX with 3.1 HP @ 9000 rpm should do a little better.

Are you going to run yours with the stock power box?

It will be interesting to see how it does with something higher load than a 17x6. It should pull it, but will it really give more flying power? The jump from a 17x6 to 18x6 is pretty dramatic. This motor only has 120 cubes and no tuned exhaust system. I was impressed to see the 108 to turn a 18x8n APC 8300. I am thinking that this motor should do a little better than the 108. I am sure there will be a lot of people under proping it and very disappointed as with those small transfer ports it is going to start going to sleep after the mid 9's.

I have a 68" yak looking for a motor. Thinking maybe this one or the 1.6FX. Fire yours up...I need some info.

_____________________________

Good Flying to you!
See Blog for RCU Video's

(in reply to seanychen)

Post #: 8

RE: *Pitts Style Muffler For OS MAX 120AX* - 1/4/2006 3:57:13 PM

Zippi

Posts: 3001
Joined: 6/29/2004
From: Evansville, IN, USA
Status: offline

My first thought was to start out with a APC 16X8. OS sugguest using 15x10-12 or 16x8-10. Fire that thing up dude and give us some feed back on the rpm's and what looks good.

quote:

ORIGINAL: seanychen

I don't think a 17x6 will show the true color of this beast, as the peak HP is developed at 9000 rpm. Something along the line of 17x8 or 18x6 is more like it. But sorry, I haven't fired mine up yet.

My OS 108 w/ Slimeline Pitts will run APC 17x6 @ 9400 rpm. This engine is rated at 3 HP @ 1x000 rpm. So the 120 AX with 3.1 HP @ 9000 rpm should do a little better.

_____________________________

"It Ain''t Lookin Good"
http://zippi.50webs.com/index.htm

(in reply to seanychen)

Post #: 9

RE: *Pitts Style Muffler For OS MAX 120AX* - 1/5/2006 7:46:21 AM

dynasel

Posts: 12
Joined: 6/19/2005
From: LahorePunjab, PAKISTAN
Status: offline

My 120AX WILL BE DELIVERED TO ME IN ABOUT A WWK TIME. I AM EAGER TO KNOW WHAT PROP WOULD BE THE BEST TO POWER UP MY SUKHOI SU-26. CURENTLY IT HAS 108FX WITH
PROP APC 15X6. AIRPLANE WEIGHT 11-LBS SO I DO NOT GET UNLIMITED CLIMB. HOW ABOUT
USING 160-FX WITH THIS APC 17X8 ?

(in reply to Zippi)

Post #: 10

RE: *Pitts Style Muffler For OS MAX 120AX* - 1/5/2006 2:15:37 PM

STG

Posts: 3498
Joined: 7/3/2003
From: New Richmond, WI, USA
Status: offline

quote:

ORIGINAL: dynasel

My 120AX WILL BE DELIVERED TO ME IN ABOUT A WWK TIME. I AM EAGER TO KNOW WHAT PROP WOULD BE THE BEST TO POWER UP MY SUKHOI SU-26. CURENTLY IT HAS 108FX WITH
PROP APC 15X6. AIRPLANE WEIGHT 11-LBS SO I DO NOT GET UNLIMITED CLIMB. HOW ABOUT
USING 160-FX WITH THIS APC 17X8 ?

I think the Skorepa wood 17x6 will be the prop for the 120ax. Depending on how restrictive the exhaust system is I think it will pull between 9,200 and 9,500 RPM and deliver about 16 pounds of thrust and immediate spool with the light wood prop. My guess is that it will pull a 18x6, but be in the lower 8's and thrust will be about the same. A 17.5x6 would probably be optimum if you could find one.
Of course this is only a guess....we will see.

____________

The 160FX will do a good job on your 11pound (to be 11.5pounds with 1.6--cg will go forward). The 17x8 is a good prop, but I think on the SU-26 your best APC prop if you are looking for good unlimited vertical is the 18x6W. You will still have more than enough forward speed with that airframe(big round cowl).

____________________

I have found that the 15x6 is not enough load for the 108. Infact, my .91FX almost pulls the 15x6 as hard as the 108. But when I start to load the motor with bigger props the motor shows its place....

Well today was not a good fly day—too rainy and windy, but I did go out and get some thrust figures. The test was with a F90 with OS 108FSR , Jec pitts muffler, restrictor sleeve removed from the carb and VP30 pump. Fuel used was Cool Power 15%. Temp 51° Humidity 76% and dupoint was 44°. I used a Rapalla fishing scale that calibrates within 1oz at 10 and 15 pounds. Elevation is at about 300 feet.

I tried six different props and to my surprise max thrust was very close between them. The props are shown below in the picture and are ordered left to right lowest to highest thrust. My measurements were rmp at 10 pounds (about hovering rpm) of thrust and rmp at max rpm/thrust.

Prop RPM at 10 pounds Max RPM& Thrust
15 x6 apc 8,900rpm 10,600 – 13.7 pounds

16 x6 zing not measured 9400- 14.6 pounds

18x8n apc 6,400 8200- 14.9 pounds

16 x5 c zing 7,900 9800- 15.1 pounds

16 x6 apc 7,700 9520- 15.2 pounds

17 x6 apc 7,100 9,200- 15.5 pounds

All these peak readings are about a 1.5 pounds better than I expected. Not sure why this is?

I am extremely happy with the way the motor runs and transition is outstanding. I made a recording of it at the end when I had the 16 x 6 zinger on. Anyone curious to how fast this 2 stoke transitions please email me and I will send the wave file to you.

< Message edited by STG -- 1/5/2006 2:18:37 PM >

_____________________________

Good Flying to you!
See Blog for RCU Video's

(in reply to dynasel)

Post #: 11

RE: *Pitts Style Muffler For OS MAX 120AX* - 1/5/2006 2:47:31 PM

seanychen

Posts: 2914
Joined: 7/20/2002
From: Canton, MI, USA
Status: offline

Hmm, sounds like 108 may generate as much thrust as 120 AX would. The 108 was a very good motor indeed, especially for 15 years ago.

_____________________________

E_Total = M*G*H + 1/2 M*V^2
When H=0, all of airplane's velocity becomes crash energy!

(in reply to STG)

Post #: 12

RE: *Pitts Style Muffler For OS MAX 120AX* - 1/5/2006 3:09:42 PM

Zippi

Posts: 3001
Joined: 6/29/2004
From: Evansville, IN, USA
Status: offline

I looked at the OS 1.08 but didn't like the price at $299.99 at Tower. I'm not sure why that engine is priced so high. Thats why I decided on the 120AX. New design and lower price.

_____________________________

"It Ain''t Lookin Good"
http://zippi.50webs.com/index.htm

(in reply to seanychen)

Post #: 13

RE: *Pitts Style Muffler For OS MAX 120AX* - 1/5/2006 3:13:08 PM

STG

Posts: 3498
Joined: 7/3/2003
From: New Richmond, WI, USA
Status: offline

quote:

ORIGINAL: seanychen

Hmm, sounds like 108 may generate as much thrust as 120 AX would. The 108 was a very good motor indeed, especially for 15 years ago.

Why do you say that? I think the 120ax will have the performance edge with 16x6 & up props, depending on the exhaust system, and it is a much smaller case size.

I am just guessing on performance though. It looks like to me to be a little brother of the 1.6FX...similar motor scaled down. Max HP is rated the same. It even uses the same rear baring as the 1.6 and 108.

No question though the 108 very good motor...to bad they could not have made it a 125 or a 130.

I think they did not do it because of the large transfer parts...it made the motor willing to spin. If they increased the displacement and let it spin up forces on the motor would be to great and it would explode!!

That is why peak H.P. is rated @16,000rpm. I know there are guys that liked to run these motors on speed planes and I think prop them for @12,000 rpm.

I forget the name of the guy here on RCU...but he does motor longevity tests using different fuels. He said the only modern O.S. motor that even comes close to making his 100 hour club(I think this is right) is the 108. Well now that motor will be gone. I think he runs them a lot harder than I do.

< Message edited by STG -- 1/5/2006 3:14:38 PM >

_____________________________

Good Flying to you!
See Blog for RCU Video's

(in reply to seanychen)

Post #: 14

RE: *Pitts Style Muffler For OS MAX 120AX* - 1/5/2006 3:20:37 PM

STG