decay

Thinking about buying a O.S. 32SX for a H9 Tribute, do they
have the extra power for the money? Or would a .36 TT
or Magnum .36 be as good for a lot less? Any ideas??

w8ye

My Feedback: (16)

The TT and Magnum are newer and run mighty good

TimC

I like my .32SX fine decay. No complaints. I have it in a little Extra 300 and it's a speedy little guy.

happypappy

My Feedback: (10)

I recently posted on another thread about the Tribute 36. At our field there is a Tribute with an OS .25 that flies very well and will barely hold a hover at full throttle. The plane flies very light and I think the performance reflects the weight advantage. This plane now has an OS .32SX on it and it really stepped up the performance of the plane. Would say that if you have that engine already to put it on there and fly it! You will not be dissapointed. Let us know! He is runnning an APC 11x4 on it.

foresterxt

My Feedback: (35)

I've had (past tense, crashed it[]) a tribute 36. I started out with a Mecoa .32, it turned similar numbers to the .32 SX on the 10x4 (13500 i believe). It flew excellent but hovered at around 4/5th and didn't have much pull out. If you you're not a pro, hovering without any pullout is tough. I then went ahead and stuck a Thunder Tiger GP42. It did a bit better on an 11x4, but still required over 3/4 throttle to hover. I manage to crash trying to get a hover down low. The OS .32 is an excellent engine, but I'm not certain it's worth the $125 they want for it. If I were you I'd get a Thunder Tiger 46 or OS AX. If you want to keep it on the cheap, get the Thunder Tiger 42, it'll make an excellent fun fly plane with some 3D potential.

Dr1Driver

I'd buy the OS .32SX. It's a LOT of bang for the buck. It is VERY reliable and user-friendly. I've owned 5 of these little jewels and had loved every one. Gobs of power, too. It'll turn an APC 10-4 at almost 14,000 on a stock muffler and 15%.

Dr.1

plasticmaster

I've never had an OS .32SX, but I have the Thunder Tiger .36 on a 3 pound profile plane and I love it. It hovers with a ton of pullout power. It spins an APC 11x3 at 14,000 rpm.

amunro

It's worth it if you love small engines that have tons of power and are stone axe reliable. I have one I ran in a fun flyer for quite a while and it's not for sale.

The SX doesn't idle as slow as the old O.S. .32F, but it's still a total powerhouse.

SWMPAR15

My Feedback: (53)

i have an os 32 in my "rookie". it is a little 3 pound speed plane. i have an ultra thrust pipe and i run an apc 8X7 prop at 18500 rpm.i use byron 15/16 fuel. this motor runs that all day and i fly i alot.noting to complain about here. it is worth every dollar you will pay for it.

asmund

My ASP (magnum) 36 runs great and I have only tached Mas 9-6 at 15300 rpm, so it is pretty strong

DarZeelon

P51,


I don't think it will last very long in this guise... This engine is designed to be spinning 12-14K, not 18.5K static and on much more, better oil...

Also, are you sure this is the best deal you could strike on an OS, for the $190 (+s&H) you already have invested???

An OS.55AX would have set you back only $150, made more power with only half the sound energy and would have flown your plane faster, without tearing itself to bits at bearing shredding RPM...

Pathous

My Feedback: (12)

Dar why does OS list the practical rpm from 2000 to 22000? This engine should have no problem running 18500.

Scott

DarZeelon

Scott,


OS does say the practical RPM for this engine is significantly higher - 22K tops.

However, it is the same OS that determined the [link=http://www.osengines.com/engines/osmg0532.html]recommended[/link] props sizes as 10x6, 10.5x6 and 11x6...

These props would be spun by this engine at ~11-13.5K RPM.

The standard bearings inside this engine are rated for 36K... So they will not really shred at 18.5K... I was figuratively speaking.
...But OS rate this engine at 1.2 HP @18K... so even the 18.5K P51 is reporting, is a bit 'over the hill'. And when this engine unloads in a high-speed pass/dive it will likely be doing over 20K...

The UltraThrust tuned muffler will make up some local torque, for this engine's lower RPM porting, but this engine will likely be even further over the hill, as far as its power output is concerned...
...The last time I looked, it is more horsepower that makes more speed - note merely more RPM.


And, despite the unwarranted high price OS charges for this engine, it is a pretty nice one.

freakingfast

My Feedback: (3)

The 32 sx is probably the best engine that OS ever made. I've abused one for years and it's still very strong. I feel that I got my money's worth many times over.
From day one I ran it with a header and pipe; Macs Products Pre-Tuned System # 1910 and pressure fitting #9051. This is one of the few times that you get an exhaust system that works as is, no cutting, that gives perfect idle, midrange, top end and transition. Great for 3D or speed. Master Airscrew 10x4 (S-2) for 3D and APC 9x6 for speed.

PS the muffler is good but the sound you hear in flight with the 10x4 is the blade tips going super sonic

DarZeelon

FKF,


Not in your life!

For its blade tips to be going at the speed of sound, this prop must be spun at no less than 26,167 RPM; slightly less if you also enter the longitudinal vector.

The important word is 'slightly'... With the flat pitch of the 10x4 prop, it would reduce the RPM needed for sonic speed at the tip, by less than 1% (0.8% actually).

freakingfast

My Feedback: (3)

Sorry Dar, you’re wrong or a few hundred are wrong on this side of the pond. In a dive, there is an incredible high pitch prop noise howl. The most noise is with a Master Airscrew 10x4 and much less with the APC 10x4. The Master Airscrew has more punch but less top end, great for 3D. If you need quiet, go up to an APC 10x5 at the cost of some performance. Unlike some other OS engines, this little engine's bearing will last, I must have at least 10 gallons through it. I now have three of these engines and there must be around twenty in the club and not one complaint. I have two Webra 35GT's(ringed) and one 36 but I can't get them to the OS's level of performance. The OS 32sx is not a low RPM motor as you would find out if you bought the setup I mentioned above and run it on 15%.

blw

My Feedback: (3)

You would hear the tips approaching supersonic speeds as they were reaching compressibility. Actually going supersonic is a completely different thing.

DarZeelon

FKF,


I ask you to recalculate and even more importantly, to understand what actually causes blade tips to make a loud noise...

Compressibility sets in as a speed of Mach 0.6-0.7 is reached; and as Barry wrote, compressibility changes the sound the blade-tip makes as it is going through the air.
Only at trans-sonic speed, does any local flow over the blade-tip approach sonic speed.


Even if the 'saw-mill' sound resembles repeated sonic booms; like that of T-6 planes, it is not that!


The only aircraft flying today, which has prop blade tips that can actually reach sonic speed; is the Tupolev Tu-95 (and variants).

This turboprop plane (14,795 ESHP each engine) can reach 925 kph (no Rare Bear, Strega, Dago Red, Etc.. can do that ) and while loitering at 20,000 ft., it can be heard 'loud and clear', by a submarine crew 200 ft. below the surface...


You're just flattering yourself by thinking that OS.32SX can bring its blade-tips to such a speed.

NM2K

My Feedback: (14)

---------------


The OS .32SX is a fantastic engine. The only thing more powerful without getting into Jett engines would be the Webra .32GT.


Ed Cregger

freakingfast

My Feedback: (3)

Dar....What ever

Back to Decay's original question; The OS 32 sx and the TT 36 pro are both great choices. If both engines had a Jett, Ultrathrust muffler or Macs muffled tuned pipe I would expect more power and top end with the OS.
I've found it harder to hover with a Jett or Ultrathrust verses a stock muffler or muffled tuned pipe. For 3D the power is too on or off with the Jett or Ultrathrust for my liking.

Kweasel

My Feedback: (29)

Supersonic or not, the prop can get too noisy with a little more rpm. Most people like it that way.

happypappy

My Feedback: (10)

Dar's way correct guys! Just do the math on a 10" prop and see for yourself!

DarZeelon

You're right on this issue!


For good 3-D performance in hover, you need a very linear power curve.

The high-performance Jett and Nelson tuned mufflers have to big a 'step' where the exhaust goes into tune.
This gives great RPM on top, but at 1/2-2/3 throttle, while you are hovering (with a normal muffler...), you can't hover...

Put the throttle stick in the 'hover position' and it loses altitude... Give it 2 more clicks and you've got 1,500 RPM more... you launch...


A very wide range tuned exhaust, like the MVVS tuned muffler (works from about half-throttle), or a non-tuned muffler, are what you need for 3-D.


Dub Jett sells his .76L BSE with a non-tuned Jett-Lite muffler, since it is intended for 3-D...

Dr1Driver

<butting in>
On a 10" prop turning 14,000, the tips are moving about 416mph, certainly VERY short of "supersonic". However, our props are nowhere near 100% efficient so cavitation will cause some noise.

Dr.1

NM2K

My Feedback: (14)

Bob Adkins mousse can pipe muffler is ideal for 3D and fun-fly applications and is easy to construct.

I still can't believe that someone hasn't jumped on the bandwagon and began offering these mufflers commercially.


Ed Cregger