OS 33GT Gasoline Engine for Pattern
12-16-2011, 12:16 PM
#101
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RE: OS 33GT Gasoline Engine for Pattern
ORIGINAL: speedracerntrixie
Bill, I have a few questions/comments. While I am not the owner of this engine and have no real business getting involved other then being a consumer whom at some point may consider buying an OS gas burner in the near future. I do have 2 50cc airplanes under construction now and the OS 55 was a consideration.
Bill, I have a few questions/comments. While I am not the owner of this engine and have no real business getting involved other then being a consumer whom at some point may consider buying an OS gas burner in the near future. I do have 2 50cc airplanes under construction now and the OS 55 was a consideration.
If you want to wow your neighbors, put a 20x12 3 blader on it, fit a ESComposites pipe to it and mount it on a soft mount. Electric like quiet set up with lots of beans
12-16-2011, 01:35 PM
#102
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RE: OS 33GT Gasoline Engine for Pattern
I can give you a little info on the engine. First, it will hand start just fine. The CDI must see 300 rpm to fire, so it takes a stronger flip than some of the other engines out there. Choke, flip until it pops, open the choke and flip until it starts. I've run the GT55 for two years now and have never had an engine in it's size range produce this much power. The GT33 is exactly the same.
Steve
Steve
ORIGINAL: speedracerntrixie
Bill, I have a few questions/comments. While I am not the owner of this engine and have no real business getting involved other then being a consumer whom at some point may consider buying an OS gas burner in the near future. I do have 2 50cc airplanes under construction now and the OS 55 was a consideration.
First off, I am curious as to why you have taken the time to run the engine twice knowing that you will have to split the case to make repairs. Obviously you will have to run the engine again after this work is complete. To me it just seems like a waste of time setting it up on the bench multiple times.
The other thing is the use of a starter. IMO the market you are trying to reach with this engine is used to hand starting engines. This alone is enough to make me skip over the OS offerings as I will not buy an engine that can't be easily hand started. OS could easily fix this via ignition timing ( Adjust the ignition firmware ), port timing or both. Obviously I'm not sure of which one or both that prevent hand starting. Having to turn over the engine fast has nothing to do with the sensor. What I think is going on is that OS has programmed the IC that controls the ignition not to trigger the coil until a certain RPM is reached. They most likely did this to prevent accidental starts. It's a simple fix, edit the firmware. Again IMO Great Planes, Hobbico and any US based hobby supplier needs to be more focused on customer service, especially now with all the available stuff outside the US. There are still lots of us that will spend the extra money on quality products as long as the customer service is up to par.
ORIGINAL: Bax
A note:
The rear cover needed is out of stock. It is cracked, but the engine can be mounted and run. We don't have engines in stock, or we'd take one out of stock and get the part. We've been assured that one is coming from O.S., in Japan.
We have successfully run the engine twice. It runs normally and very, very well.
Please note that the instructions for the engine do state that it is intended to be started with an electric starter. Please see the last paragraph of page 16 in the instruction manual. The engine can be hand-started, but you must get it really flipping fast, because the engine does need to have the prop hub moving fast enough to excite the sensor. It's not surprising that hand-starting could be difficult because of this.
A note:
The rear cover needed is out of stock. It is cracked, but the engine can be mounted and run. We don't have engines in stock, or we'd take one out of stock and get the part. We've been assured that one is coming from O.S., in Japan.
We have successfully run the engine twice. It runs normally and very, very well.
Please note that the instructions for the engine do state that it is intended to be started with an electric starter. Please see the last paragraph of page 16 in the instruction manual. The engine can be hand-started, but you must get it really flipping fast, because the engine does need to have the prop hub moving fast enough to excite the sensor. It's not surprising that hand-starting could be difficult because of this.
First off, I am curious as to why you have taken the time to run the engine twice knowing that you will have to split the case to make repairs. Obviously you will have to run the engine again after this work is complete. To me it just seems like a waste of time setting it up on the bench multiple times.
The other thing is the use of a starter. IMO the market you are trying to reach with this engine is used to hand starting engines. This alone is enough to make me skip over the OS offerings as I will not buy an engine that can't be easily hand started. OS could easily fix this via ignition timing ( Adjust the ignition firmware ), port timing or both. Obviously I'm not sure of which one or both that prevent hand starting. Having to turn over the engine fast has nothing to do with the sensor. What I think is going on is that OS has programmed the IC that controls the ignition not to trigger the coil until a certain RPM is reached. They most likely did this to prevent accidental starts. It's a simple fix, edit the firmware. Again IMO Great Planes, Hobbico and any US based hobby supplier needs to be more focused on customer service, especially now with all the available stuff outside the US. There are still lots of us that will spend the extra money on quality products as long as the customer service is up to par.
12-16-2011, 02:07 PM
#103
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RE: OS 33GT Gasoline Engine for Pattern
Steve:
There's something else going on with Matt's 33GT. We even went to a different brand CDI unit it on the assumption that the stock CDI had some sort of minimum RPM code built into it. It really just acts like a fuel draw problem, my theory being that those 4reeds need more negative pressure than a typical 2 reed setup, possibly because their individual surface areas are relatively small, though their combined surface area is probably larger than a comparable sized engine's 2 reed system. Matt's engine behaved well for the first 3 or 4 flights, then became a problem. We looked at various possibilities, leaks, warped reed block and the like, and it really didn't solve anything. It will be interesting to see what comes back from the repair.
There's something else going on with Matt's 33GT. We even went to a different brand CDI unit it on the assumption that the stock CDI had some sort of minimum RPM code built into it. It really just acts like a fuel draw problem, my theory being that those 4reeds need more negative pressure than a typical 2 reed setup, possibly because their individual surface areas are relatively small, though their combined surface area is probably larger than a comparable sized engine's 2 reed system. Matt's engine behaved well for the first 3 or 4 flights, then became a problem. We looked at various possibilities, leaks, warped reed block and the like, and it really didn't solve anything. It will be interesting to see what comes back from the repair.
12-16-2011, 02:17 PM
#104
RE: OS 33GT Gasoline Engine for Pattern
Steve, I have no doubts about the engine it's self. I'm just wondering why OS would set up the ignition this way? 300 RPM on a hand flip is rather high. Thye RCEXL ignition has no minimum rpm, the DAand 3W ignitions do have a minimum although I don't know what the exact number is, Iknow it is lower then 300 RPM. Has anyone there at Hobbico considered bringing this up with OS? To me it just seems like alot of wear and tear on the end user so OS feels safer about accidental starts. BTW the reason I am opposed to starters on these large models is Ihave seen too many close calls. One guy pushing on the airplane while another pushes into the starter. I've seen the starter slip off the spinner and the guy with the starter almost fall into the prop arc. Once again IMO the more popular gassers have historically been the ones that start easily and have good support. Take ZDZ for example. Not a bad engine but they broke from starting tradition when they suggested propping at full throttle with ignition off then set to a high idle with ignition on. Then the service was poor.
12-16-2011, 02:26 PM
#105
RE: OS 33GT Gasoline Engine for Pattern
ORIGINAL: NJRCFLYER2
Steve:
There's something else going on with Matt's 33GT. We even went to a different brand CDI unit it on the assumption that the stock CDI had some sort of minimum RPM code built into it. It really just acts like a fuel draw problem, my theory being that those 4reeds need more negative pressure than a typical 2 reed setup, possibly because their individual surface areas are relatively small, though their combined surface area is probably larger than a comparable sized engine's 2 reed system. Matt's engine behaved well for the first 3 or 4 flights, then became a problem. We looked at various possibilities, leaks, warped reed block and the like, and it really didn't solve anything. It will be interesting to see what comes back from the repair.
Steve:
There's something else going on with Matt's 33GT. We even went to a different brand CDI unit it on the assumption that the stock CDI had some sort of minimum RPM code built into it. It really just acts like a fuel draw problem, my theory being that those 4reeds need more negative pressure than a typical 2 reed setup, possibly because their individual surface areas are relatively small, though their combined surface area is probably larger than a comparable sized engine's 2 reed system. Matt's engine behaved well for the first 3 or 4 flights, then became a problem. We looked at various possibilities, leaks, warped reed block and the like, and it really didn't solve anything. It will be interesting to see what comes back from the repair.
Interesting that it was fine for the first few runs. If it were the neg pressure thing I would think it would have gotten better. I doubt the reeds would have any break it but if they did, they would only get more flexible and as the ring seats the neg pressure would increase and make the reeds come off the reed cage even better. It would also make them seal better too. Difficult to diagnose an engine with a different brand ignition. It's hard to know if the advance curves are compatible and weather to set up the sensor at TDC or 28 degrees advanced as was the case when I set up a DA 50 with an RCEXL.
12-16-2011, 02:29 PM
#106
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Thread Starter
RE: OS 33GT Gasoline Engine for Pattern
ORIGINAL: NJRCFLYER2
Steve:
There's something else going on with Matt's 33GT. We even went to a different brand CDI unit it on the assumption that the stock CDI had some sort of minimum RPM code built into it. It really just acts like a fuel draw problem, my theory being that those 4 reeds need more negative pressure than a typical 2 reed setup, possibly because their individual surface areas are relatively small, though their combined surface area is probably larger than a comparable sized engine's 2 reed system. Matt's engine behaved well for the first 3 or 4 flights, then became a problem. We looked at various possibilities, leaks, warped reed block and the like, and it really didn't solve anything. It will be interesting to see what comes back from the repair.
Steve:
There's something else going on with Matt's 33GT. We even went to a different brand CDI unit it on the assumption that the stock CDI had some sort of minimum RPM code built into it. It really just acts like a fuel draw problem, my theory being that those 4 reeds need more negative pressure than a typical 2 reed setup, possibly because their individual surface areas are relatively small, though their combined surface area is probably larger than a comparable sized engine's 2 reed system. Matt's engine behaved well for the first 3 or 4 flights, then became a problem. We looked at various possibilities, leaks, warped reed block and the like, and it really didn't solve anything. It will be interesting to see what comes back from the repair.
All of my trials and tribulations were covered in a letter to Hobbyservices. They should have my problems encountered in detail. Thanks for getting involved
12-16-2011, 02:30 PM
#107
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RE: OS 33GT Gasoline Engine for Pattern
We got it to run witha Syssa CDI, which Ibelieve is an Rcexl,but it was very hard to start. Basically, just as hard to start as it was with the stock CDI. It really looks like a fuel draw issue.
12-16-2011, 02:49 PM
#108
RE: OS 33GT Gasoline Engine for Pattern
Ed, that makes good sense as the RCEXL unit requires no min RPM to fire. I'm sure Matt will let us know what the end fix is.
Matt. I'm quite interested in your DLE 55 setup. What header did you use and what was the length that worked the best? Pretty sure this is the setup I will go with.
Matt. I'm quite interested in your DLE 55 setup. What header did you use and what was the length that worked the best? Pretty sure this is the setup I will go with.
12-16-2011, 03:09 PM
#109
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RE: OS 33GT Gasoline Engine for Pattern
ORIGINAL: speedracerntrixie
Ed, that makes good sense as the RCEXL unit requires no min RPM to fire. I'm sure Matt will let us know what the end fix is.
Matt. I'm quite interested in your DLE 55 setup. What header did you use and what was the length that worked the best? Pretty sure this is the setup I will go with.
Ed, that makes good sense as the RCEXL unit requires no min RPM to fire. I'm sure Matt will let us know what the end fix is.
Matt. I'm quite interested in your DLE 55 setup. What header did you use and what was the length that worked the best? Pretty sure this is the setup I will go with.
The soft mount is my own; similar to the Hyde. I'm sure Merle will build one for you (200+ $) or I can help you through a build if you are so inclined. I have a thread somewhere in these pages on the building of a stand off type of mount. That thread was written around a ZDZ40 engine but the techniques are the same. My mount has an OD of 5 1/8" and is 15/16" thick (not terribly critical, you can make it +/- 1/8" and it will work well). Weighs just over 4 ozs.
I admit I was skeptical at first because the power output on pipe was terrific, but now after 60 flights give or take (about 4-5 gallons avgas) I no longer am. Prop was the Mezjlik 20x12. I broke the prop on it's last flight and am in process of casting a mold from it
12-16-2011, 03:42 PM
#110
RE: OS 33GT Gasoline Engine for Pattern
Thanks Matt, my only real concern is the longevity with the engine. I don"t really need the noise reduction so I will hard mount but I wanted to go with a pipe on this one. Even with my DA 50 it seemed as if I was replacing bearings and carbs every 200 flights or so. Funny, with my 150 as long as I ran clean fuel and good oil I didn't have to even think about it even after 500 flights.
12-16-2011, 08:32 PM
#111
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RE: OS 33GT Gasoline Engine for Pattern
What is the ignition timing set at on this engine? This is one of the first questions Ralph, Jody or TOM would have asked. Is the pickup location adjustable?
12-16-2011, 08:46 PM
#112
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RE: OS 33GT Gasoline Engine for Pattern
ORIGINAL: speedracerntrixie
Thanks Matt, my only real concern is the longevity with the engine. I don''t really need the noise reduction so I will hard mount but I wanted to go with a pipe on this one. Even with my DA 50 it seemed as if I was replacing bearings and carbs every 200 flights or so. Funny, with my 150 as long as I ran clean fuel and good oil I didn't have to even think about it even after 500 flights.
Thanks Matt, my only real concern is the longevity with the engine. I don''t really need the noise reduction so I will hard mount but I wanted to go with a pipe on this one. Even with my DA 50 it seemed as if I was replacing bearings and carbs every 200 flights or so. Funny, with my 150 as long as I ran clean fuel and good oil I didn't have to even think about it even after 500 flights.
12-17-2011, 06:41 AM
#114
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RE: OS 33GT Gasoline Engine for Pattern
ORIGINAL: MTK
The header was a stock return to center from DA. At least I think it is stock....it has a flex joint at the goose neck wrapped with teflon unsintered tape. The pipe is the stock ESC G55 carbon unit. I'm using a length of 28'' from exhaust port flange, around the goose neck to the baffle. The length is not terribly critical at +/- 1''. Output won't change unless you went way out on the length
The header was a stock return to center from DA. At least I think it is stock....it has a flex joint at the goose neck wrapped with teflon unsintered tape. The pipe is the stock ESC G55 carbon unit. I'm using a length of 28'' from exhaust port flange, around the goose neck to the baffle. The length is not terribly critical at +/- 1''. Output won't change unless you went way out on the length
Another header that fits the DLE/DA50-55-60 is the Hatori. Just bought one of them from Graves RC. A little more expensive than the DA at around 80$, except it is aluminum versus steel and fits very tightly around the cylinder head. It intended for narrow Pattern style fuses or warbirds.
DA's header has a flex joint and I highly recommend a flexible joint be set-up in the Hatori too. Flexibility is necessary otherwise header breaks will happen. I also soft mount to pipe (simple Dave Brown style set-up) to keep things from snapping apart
12-17-2011, 06:59 AM
#115
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RE: OS 33GT Gasoline Engine for Pattern
ORIGINAL: PlaneKrazee
Matt,
Do you notice the thrust change with the soft mount and no nose ring? I'm searching for your build thread now.
Matt,
Do you notice the thrust change with the soft mount and no nose ring? I'm searching for your build thread now.
As the engine is revved up, thrust moves it forward about 1/32" which is something you can see. You also see the cylinder rotate on the axis a bit in the opposite direction of prop rotation The engine is supported at it's cg and the cg is centered on the rubber isolation rings. Resultant side moments are zero.
My DLE55's sensor location for example was modified from stock to accommodate a nose ring. I intend to use the engine in my latest Pattern design. Running the combo in a 13 pound, 2 meter Extra was an eyeopener power and thrust wise. And the Pattern plane won't weigh much more than 11 pounds. Would be able to fly the bird at very low throttle setting, very slowly, with instant thrust on demand
12-17-2011, 11:46 AM
#117
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RE: OS 33GT Gasoline Engine for Pattern
ORIGINAL: speedracerntrixie
Matt, I appriciate you comments about the soft mount but as these will be used for IMAC competition I will contunue to hard mount. I have been hard mounting for 14 years now without any ill results.
Matt, I appriciate you comments about the soft mount but as these will be used for IMAC competition I will contunue to hard mount. I have been hard mounting for 14 years now without any ill results.
12-17-2011, 01:00 PM
#118
RE: OS 33GT Gasoline Engine for Pattern
ORIGINAL: NJRCFLYER2
Doesn't IMAC still have anoise score? Should be a slam-dunk 10 if you outfit your engine the way Matt describes. Plus, your servos will all last longer and you will use a lot less battery capacity each flight. Everything lasts longer, and amazingly, you get a little more usable power delivered to the prop. If you think about it, any energy that is not wasted on rattling the airframe and producing acoustic waves from the airframe is going somewhere else - into the prop!
ORIGINAL: speedracerntrixie
Matt, I appriciate you comments about the soft mount but as these will be used for IMAC competition I will contunue to hard mount. I have been hard mounting for 14 years now without any ill results.
Matt, I appriciate you comments about the soft mount but as these will be used for IMAC competition I will contunue to hard mount. I have been hard mounting for 14 years now without any ill results.
IMAC does have a sound score. At the end of the flight the judge gives you a score of 1 to 10. In reality what happens at least here in the SW region is that if you rip the prop you get 0, if you are running mufflers and managed the throttle you get a 5, if you have canisters and use good throttle management you get a 10. 90% of the time the judge just gives out 5's. A 50cc airplane with an ES pipe and correct prop is already way ahead of most. My major concern with a soft mount is that there is no way to run a nose ring on these and the unlimited sequence has no less then 13 snaps. Thats a minimum of 26 snaps per flight. I'm concerned about the longevity with that type of abuse not to mention the engine moving around during the snap. The last Laser Ihad like the ones I am building had a hard mounted DA 50 with a muffler. The sound was very reasonable and I had about 500 flights on it with no noticable vibration damage. The pipe will smoothen out the engine some so I will already be better off. You of course are correct about less current consumed from the RX battery.
12-17-2011, 01:19 PM
#119
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RE: OS 33GT Gasoline Engine for Pattern
It is more difficult to attach a nose ring with a removable cowl model, but it can be done. Bob Moulder did it in his Focus II with a SAP180 and it worked great. Basically, he made a CF tube mount that held the nose ring. You can do without it if the mount is made a little stiffer. You lose some of the vibration damping, but it is still better than a hard mount. I've runsoft mounts with and without noseringswith 2C glow, and it's workable. It's just a question of tradeoffs between that bit of wobble you get without the nose ring when hitting high G's, and the longevity of your servo pots & gears. I think it's still worth it in most cases for engines of this size.
12-17-2011, 01:41 PM
#120
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RE: OS 33GT Gasoline Engine for Pattern
ORIGINAL: NJRCFLYER2
It is more difficult to attach a nose ring with a removable cowl model, but it can be done. Bob Moulder did it in his Focus II with a SAP180 and it worked great. Basically, he made a CF tube mount that held the nose ring. You can do without it if the mount is made a little stiffer. You lose some of the vibration damping, but it is still better than a hard mount. I've run soft mounts with and without nose rings with 2C glow, and it's workable. It's just a question of tradeoffs between that bit of wobble you get without the nose ring when hitting high G's, and the longevity of your servo pots & gears. I think it's still worth it in most cases for engines of this size.
It is more difficult to attach a nose ring with a removable cowl model, but it can be done. Bob Moulder did it in his Focus II with a SAP180 and it worked great. Basically, he made a CF tube mount that held the nose ring. You can do without it if the mount is made a little stiffer. You lose some of the vibration damping, but it is still better than a hard mount. I've run soft mounts with and without nose rings with 2C glow, and it's workable. It's just a question of tradeoffs between that bit of wobble you get without the nose ring when hitting high G's, and the longevity of your servo pots & gears. I think it's still worth it in most cases for engines of this size.
The nose rings I've made recently were simple 1/32" aircraft ply glassed on both sides. I have also used rings completely made of rubber.....worked fine. In fact, for some engines with large prop drives, a rubber nose ring is a simple solution since you can stretch it over the drive washer. That's what I've had to do on the Mintor for example
12-19-2011, 08:51 AM
#121
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RE: OS 33GT Gasoline Engine for Pattern
ORIGINAL: MTK
The nose rings I've made recently were simple 1/32'' aircraft ply glassed on both sides. I have also used rings completely made of rubber.....worked fine. In fact, for some engines with large prop drives, a rubber nose ring is a simple solution since you can stretch it over the drive washer. That's what I've had to do on the Mintor for example
The nose rings I've made recently were simple 1/32'' aircraft ply glassed on both sides. I have also used rings completely made of rubber.....worked fine. In fact, for some engines with large prop drives, a rubber nose ring is a simple solution since you can stretch it over the drive washer. That's what I've had to do on the Mintor for example
12-19-2011, 10:41 AM
#123
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RE: OS 33GT Gasoline Engine for Pattern
What do you want for Christmas?
http://www.rcuniverse.com/forum/m_10...m.htm#10866446
http://www.rcuniverse.com/forum/m_10...m.htm#10866446
12-19-2011, 02:27 PM
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RE: OS 33GT Gasoline Engine for Pattern
Ummm, minimum rpm to excite the sensor? They use a traditional magnet/hall sensor arrangement don't they?
Warming up your pitching arm for a speed of sound 270degree flip died out with magneto ignition.
BTW the cdi in the YS will fire at near zero rpm, it just needs to see the magnet move away from the sensor. The only "problem" with the YS arrangement is that at hand flipping speed it's probably going to spark at 20+ degrees before top dead center.
Warming up your pitching arm for a speed of sound 270degree flip died out with magneto ignition.
BTW the cdi in the YS will fire at near zero rpm, it just needs to see the magnet move away from the sensor. The only "problem" with the YS arrangement is that at hand flipping speed it's probably going to spark at 20+ degrees before top dead center.
12-19-2011, 02:41 PM
#125
RE: OS 33GT Gasoline Engine for Pattern
ORIGINAL: bjr_93tz
Ummm, minimum rpm to excite the sensor? They use a traditional magnet/hall sensor arrangement don't they?
Warming up your pitching arm for a speed of sound 270degree flip died out with magneto ignition.
BTW the cdi in the YS will fire at near zero rpm, it just needs to see the magnet move away from the sensor. The only "problem" with the YS arrangement is that at hand flipping speed it's probably going to spark at 20+ degrees before top dead center.
Ummm, minimum rpm to excite the sensor? They use a traditional magnet/hall sensor arrangement don't they?
Warming up your pitching arm for a speed of sound 270degree flip died out with magneto ignition.
BTW the cdi in the YS will fire at near zero rpm, it just needs to see the magnet move away from the sensor. The only "problem" with the YS arrangement is that at hand flipping speed it's probably going to spark at 20+ degrees before top dead center.
As stated in a previously, it's the firmware that was burned into the IC controling the CDI. It would be an easy change for OS to make. I guess the Hobbico guys arent going to address that for us. As far as the YS, it should be starting up at close to zero. The placement of the sensor is not always the point of fire. Some ignitions have you set them up at zero and then advances as the RPMs go up. Some ignitions have you set them up 28 degrees advanced then start up at a full retard and decrease the amount of retard as RPMs increase.