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OS 33GT Gasoline Engine for Pattern

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Old 11-08-2011, 08:53 PM
  #26
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Default RE: OS 33GT Gasoline Engine for Pattern

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Old 11-09-2011, 01:10 PM
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Default RE: OS 33GT Gasoline Engine for Pattern


[/quote]
I have not used any muffler on any of my gasoline engines so I don't have a first hand comparison. But judging from power/rpm numbers people are quoting for specific props on muffler, a pipe gives considerable boost in output over the quoted numbers. A pipe enables higher pitches to be used for the same rpm and diameter. OR larger diameter for the same pitch and rpm, but you will have to be careful with larger diameters because noise can increase fast.

A pipe also significantly reduces the noise footprint over mufflers. Expect to be drowned out by any muffled engine flying. Couple a pipe with a 3 bladed prop and a soft mount and you will hear even a larger difference in noise footprint.

I promised photos but just couldn't get to it last night. I may get to it tonight
[/quote]

I've often wondered as we lengthen our pipes to "soften" the transition (or "coming on the pipe) that we hit a point where ultimate horsepower is not increased with a tuned pipe. I ran an OS 1.40 on both a tuned pipe and a muffler with good success turning a 4 blade prop (and extremely quiet on both). I did notice the mid range wasn't as strong on the muffler, but the ultimate rpm's were pretty close to the pipe, which means the engine was producing similar ultimate HP. The muffler gave a more linear response to throttle.
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Old 11-09-2011, 02:03 PM
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Default RE: OS 33GT Gasoline Engine for Pattern

I hope to play with the engine this weekend. From the very limited running I've done the engine seems to respond more linearly to throttle than my SAP 30cc did on pipe. I never could get rid of the jump on pipe at around 3500 rpm with the SAP, no matter what prop I used or the pipe setting (from nominal at 27" to baffle all the way to 31").

The OS is a different breed of cat it appears. I'll know much more after I run it in flight with larger props. Break in will happen with an 18x12 carbon-wood MDK hybrid. The SAP 30cc choked on that prop so it will be enlightening either way.
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Old 11-09-2011, 02:26 PM
  #29
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Default RE: OS 33GT Gasoline Engine for Pattern

Matt, if it delivers sufficient torque at 6500 or 6700 rpm to keep pulling in a sustained vertical, I will be impressed.

Sorry to have abandoned the pattern gasser holy grail after one season but I am neither as persistent nor as knowledgeable as you guys having this discussion.

I can't wait to see what you're flying next spring in Jackson!

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Old 11-09-2011, 03:02 PM
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Default RE: OS 33GT Gasoline Engine for Pattern


Quote:
ORIGINAL: cmoulder

Matt, if it delivers sufficient torque at 6500 or 6700 rpm to keep pulling in a sustained vertical, I will be impressed.

Sorry to have abandoned the pattern gasser holy grail after one season but I am neither as persistent nor as knowledgeable as you guys having this discussion.

I can't wait to see what you're flying next spring in Jackson!

Bob, please, no apologies required or necessary......

Derivative.....DLE55 piped, on 3 blade prop. Just an outstanding combination and eerie quiet for anything, not just a gassie. Wait til you see this combo in action. Let me put it this way....right now I have 3 gallons through this combo and it has become a known. Super simple running; power to burn and unreal brakes. Better than most anything I've seen

The OS might work or might not. The fuselage of my new design is being prepped for the DLE. Derivative no 2 may take the OS.... I'll see how it goes

Once I have the plane, getting enough practice on it will be the key on how well I present next year. Doing all the R&D single handed is very time consuming; but heck that's what I do and how I derive the fun out of this
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Old 11-10-2011, 03:47 PM
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Default RE: OS 33GT Gasoline Engine for Pattern

Completed the installation this morning and tried to get the engine started. Well, easier said than done. On the bench the engine worked simply and easily but in the plane, for an unknown reason, it was quite a bear. I suspect the CDI module programming may be an issue. Also quite strangely for a gas engine, it started backwards several times so ignition timing could be off a bit.

However, once started it ran well putting out gobs of power. I decided to run the MDK 18x12 hybrid prop. My SAP 30 cc would not turn this prop without bogging down in the verticals so it was very interesting to me to see the OS33 turn this prop with great authority. I didn't measure rpm...... By ear I'd put it around 8300. Most importantly, the verticals were effortless but I have the engine slightly on the rich side. Two flights were taken today and both were really strong on power.

Got to figure out how this CDI module needs to be treated......
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Old 11-11-2011, 06:50 AM
  #32
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Default RE: OS 33GT Gasoline Engine for Pattern


Quote:
ORIGINAL: cmoulder

Matt, if it delivers sufficient torque at 6500 or 6700 rpm to keep pulling in a sustained vertical, I will be impressed.


It appears that it has tork to burn at 6500 rpm. I am pretty impressed so far with the output but it's early. More this weekend I hope. It's a little noisy with a 2 blade up front. I'll see how it does with a 3 blade soon

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Old 11-11-2011, 08:10 AM
  #33
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Default RE: OS 33GT Gasoline Engine for Pattern

Quote:
It appears that it has tork to burn at 6500 rpm. I am pretty impressed so far with the output but it's early. More this weekend I hope. It's a little noisy with a 2 blade up front. I'll see how it does with a 3 blade soon
Sounds good, Matt!

Maybe a 16x12 3-blade, if there is such a beast.

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Old 11-11-2011, 12:55 PM
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Default RE: OS 33GT Gasoline Engine for Pattern


Quote:
ORIGINAL: cmoulder

Quote:
It appears that it has tork to burn at 6500 rpm. I am pretty impressed so far with the output but it's early. More this weekend I hope. It's a little noisy with a 2 blade up front. I'll see how it does with a 3 blade soon
Sounds good, Matt!

Maybe a 16x12 3-blade, if there is such a beast.

I have an old Bolly carbon 16x11 3 blade. Ran it on the Webra 160 years ago. It was noisy as heck on the ground (compared to a 17x12 apc) so this is no solution except to see how the load stacks up. Working on a 18x10 3 blade hybrid. Mejzlik also ahs an 18x10 3 blade carbon and I may get one of them some day.

BTW I just received the Hatori headers #2301 and 2551. Very nice looking, very light. Compared to the stainless DA header I'm using on the DLE55, this is less than 1/2 the weight. The flange is welded to the tube at the bend so it shouldn't break there.
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Old 11-12-2011, 04:03 AM
  #35
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Default RE: OS 33GT Gasoline Engine for Pattern

Yep, not that many 3-blade choices with APC. And that Mejz ain't too cheap!

I assume your hybrid is the CF laminated Xoar e-prop. I may have a couple of 16x12's to donate to the cause, thinking that the smaller diameter may keep the tip speed below mach .666
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Old 11-12-2011, 01:50 PM
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Default RE: OS 33GT Gasoline Engine for Pattern

Hello Matt

How goes the plane in downline, is it slow as with engine 4 strokes ?
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Old 11-12-2011, 04:59 PM
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Quote:
ORIGINAL: papaone

Hello Matt

How goes the plane in downline, is it slow as with engine 4 strokes ?
The OS is a large unknown still. Don't have enough running with it to know one way or another. The main thing I was trying for was to get some runs under it's belt and break the thing in. I've run into a situation that has been hard to assess. Sending the engine back to Tower for service. It looks like either the carb has gone south after 5 tankfuls or the reed housing has warped. Suddenly, can not get enough fuel into the engine. Disappointing! Reminds me of the old YS140L days with bad regulator

If my experience with the DLE55 and 3 blade prop is any example, it should be better than most in regard to brakes. The DLE55 with a 20x12 3 blade has it all so far: great power, terrific transition and very good brakes on downlines compared to either glow or electric. However these characteristics are not strictly the engine....the large plane has quite a bit to do with that. The wing of the extra is over 1200 square inches and the fuse is larger than the typical pattern fuse.

This powerplant is proving to be one heck of a combo. Main reason why my new pattern model will be using this combo next year.
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Old 11-13-2011, 12:06 AM
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Default RE: OS 33GT Gasoline Engine for Pattern

Hi Matt,
Could you please tell us more about your DLE55 powerplant (brand of pipe/propeller, lenght of header)?
Thanks

Roberto
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Old 11-13-2011, 05:17 AM
  #39
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Default RE: OS 33GT Gasoline Engine for Pattern

Hi Matt,

One more. Are you making the 5 kg?

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Old 11-13-2011, 04:41 PM
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Quote:
ORIGINAL: Roberto B.

Hi Matt,
Could you please tell us more about your DLE55 powerplant (brand of pipe/propeller, lenght of header)?
Thanks

Roberto
I have the info in the EF 78" Extra thread. Also show all the mods I made to try to make weight. The powerplant as is right now is just about the same weight as an electric powerplant, at just under 2 kg. Except the electric planes are built a bit lighter than wet power planes. Also, the header I am using is a bit heavy (DA50cc return to center). The Hatori header with an extension pipe will lose another couple ounces. Header length is stock DA50cc, 11" from spark plug around the tube curve to the end of the tube.
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Old 11-13-2011, 04:57 PM
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Quote:
ORIGINAL: vbortone

Hi Matt,

One more. Are you making the 5 kg?

With the DLE55? Will be close! See post above Vince

But heck even if it comes out 1 pound over, it really doesn't matter to me. The Extra weighs around 13 pounds now and is tossed around like a rag doll with that much power. If a 1200 square inch Pattern plane weighs in at 12 pounds, it would be just right actually. I cut the foam a few months ago and panels are 542 square inches each; entrained are in the fuse is about 140 sq in. This Pattern plane will be a true 2x2 except larger than anything else right now. I don't subscribe to the 800 sq in wings theory; smaller wings don't fly better in my opinion.

BTWI'll let you in on a little secret: that much power up front takes about a dozen flights to get used to. Now, the plane feels normal once again, except much more fun. And the large airplane flies at a very comfortable speed. slower than many Pattern planes
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Old 11-20-2011, 12:23 PM
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Default RE: OS 33GT Gasoline Engine for Pattern

Hi Mattk

why you don't used a tuned pipe on your OS33gt. the tuned with a good tuning provides about an increase of 500 to 600 rpm but it is not the case with the canister .
for exemple I'm runing tests on the RCGF 32 and the using of a tuned pipe on the APC 20x10,5 and the 19x11 allowed me to obtain theses results :




regards

steph
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Old 11-20-2011, 03:11 PM
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Default RE: OS 33GT Gasoline Engine for Pattern


Quote:
ORIGINAL: MTK



The OS is a large unknown still. Don't have enough running with it to know one way or another. The main thing I was trying for was to get some runs under it's belt and break the thing in. I've run into a situation that has been hard to assess. Sending the engine back to Tower for service. It looks like either the carb has gone south after 5 tankfuls or the reed housing has warped. Suddenly, can not get enough fuel into the engine. Disappointing! Reminds me of the old YS140L days with bad regulator

The OS 33 GT was sent back to Tower Hobbies, actually hobbyservices. Turns out that once the engine or any iten has been removed from original packaging, it is considered a warranty item by Tower. Hobbyservices handles warranty. I didn't know that.

Really really hope that this engine can run reliably. It is a powerhouse and all you might want to power a pattern plane. Time will tell if the engine is simply a lemon or the design is no good having been released before the bugs were worked out by OS
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Old 11-21-2011, 03:05 AM
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So far so good, after getting OS GT 33 taken 15 days delivery to Korea.
Breaking in with 18X10 Hawk wooden prop, gas/motul 800 (33:1) with Stock muffler gave 7500 RPM, followed by the manual, highest RPM on low speed needle then opened 90 degree, highest RPM (7800) on high speed needle then 30 degree open.
Just 2 liters through on the GT33, it gave very reliable speed up without any hesitation. Many mentioned, throtle response is nearly linear.
Manual suggests to use electric starter, but due to too much torgue it failed to turn with electric starter. By hand start without enough speed, the engine turns backward. Matt K mentioned already. But hand start on the middle part of the prop, not on the end tip of prop resulted positive forward engne start.
The sound and vibration are much softer than any other gasser, I experienced.
After removing DLE 30, mounted it on Rock&Roll with Cannister for DLE 30, RPM droped to 6800 RPM, but better than DLE 30 which gave 6500 RPM, but unstable. During engine running it suddenly stoped at high RPM or even fordward revolution turns into barkward. It is scary. Weather was colder 7 degree C (45 degree F).
After more precise needle setup, maiden flight was succesful. I believe, it will give better results after full break-in and less oil contents.
I am waiting Hyde mount which is known to reduce noisy and vibration, but also even giving more RPM and lowering engine exhaust temperatre, resulting in better engine efficiency.
I am waiting the Hyde mount for my Smaragd. I will post some photo and results.
Matt K, I hope you had a lemon not the design problem. If it is due to design problem, you are waisting too much time and efforts, me too.
Hope to hear good news from Tower.
Good Luck and Regards, MATT K.
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Old 11-21-2011, 06:26 AM
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Default RE: OS 33GT Gasoline Engine for Pattern

Quote:
ORIGINAL: choihjin

So far so good, after getting OS GT 33 taken 15 days delivery to Korea.
Breaking in with 18X10 Hawk wooden prop, gas/motul 800 (33:1) with Stock muffler gave 7500 RPM, followed by the manual, highest RPM on low speed needle then opened 90 degree, highest RPM (7800) on high speed needle then 30 degree open.
Just 2 liters through on the GT33, it gave very reliable speed up without any hesitation. Many mentioned, throtle response is nearly linear.
Manual suggests to use electric starter, but due to too much torgue it failed to turn with electric starter. By hand start without enough speed, the engine turns backward. Matt K mentioned already. But hand start on the middle part of the prop, not on the end tip of prop resulted positive forward engne start.
The sound and vibration are much softer than any other gasser, I experienced.
After removing DLE 30, mounted it on Rock&Roll with Cannister for DLE 30, RPM droped to 6800 RPM, but better than DLE 30 which gave 6500 RPM, but unstable. During engine running it suddenly stoped at high RPM or even fordward revolution turns into barkward. It is scary. Weather was colder 7 degree C (45 degree F).
After more precise needle setup, maiden flight was succesful. I believe, it will give better results after full break-in and less oil contents.
I am waiting Hyde mount which is known to reduce noisy and vibration, but also even giving more RPM and lowering engine exhaust temperatre, resulting in better engine efficiency.
I am waiting the Hyde mount for my Smaragd. I will post some photo and results.
Matt K, I hope you had a lemon not the design problem. If it is due to design problem, you are waisting too much time and efforts, me too.
Hope to hear good news from Tower.
Good Luck and Regards, MATT K.
Uh Oh.....That's not good news. I am sorry to hear similar issues as mine. That does not speak well for the engine design. I wish I had measured the timing on it. It sounds like it way too retarded and is the likely cause of all these problems

As I recall, the 140RX had carburetion issues when first released too. Their 200 4 stroke has crankshaft issues, I have heard. I am surprised because I have always had the impression that OS did considerable alpha testing before sending their product out to the market. YS on the other hand often used us modelers as beta testers. Well, so much for impressions. The reality is something different.

BTW- I also have a Mintor 38 in test right now. I don't have it piped yet. Can't seem to find a header for the 38. The exhaust flange would need an adapter so that available headers (Hatori or Karl Mueller) could be fitted. The Mintor, in direct contrast, is so easy to start and run it makes this chore simple. Too early to tell what the performance is like since I've only played with an 18x10 apc, getting respectable power. Will try to fit the engine into my EF EXtra over the Thankgiving holiday and get a few flights on it to see for real what it can do
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Old 11-21-2011, 02:05 PM
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Default RE: OS 33GT Gasoline Engine for Pattern

Mintor make headers for their other engines, I suspect they will have headers and cans for the 33cc and 38cc in the new year  as well.
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Old 11-22-2011, 07:31 AM
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Quote:
ORIGINAL: TimBle

Mintor make headers for their other engines, I suspect they will have headers and cans for the 33cc and 38cc in the new year as well.
Just a couple runs so far (about 1 litter of gas) but I can tell the piston fit is superior than that of the OS33GT.

Exhaust adapter has been completed; engine will be run this weekend on pipe
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Old 11-22-2011, 07:49 PM
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Default RE: OS 33GT Gasoline Engine for Pattern


Quote:
ORIGINAL: MTK


Exhaust adapter has been completed; engine will be run this weekend on pipe

Here are a few photos

Also note the soft mount for the pipe....simple, effective. Doesn't need to be heavy or complicated, to work
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Old 11-22-2011, 07:53 PM
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Default RE: OS 33GT Gasoline Engine for Pattern


Quote:
ORIGINAL: MTK


Here are a few photos

Also note the soft mount for the pipe....simple, effective. Doesn't need to be heavy or complicated, to work
a couple more
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Old 11-23-2011, 02:36 AM
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Default RE: OS 33GT Gasoline Engine for Pattern

That sure is a nice looking engine.
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