racerman27410

I just adjusted my timing this evening.. it was also set for 32 degrees...reset to 28 degrees running the stock OS ignition.

the engine now starts easily with no hint of trying to run backward.

will flight test it tomorrow.

MTK

Flew one flight today. However my arm almost fell off flipping the damned thing....I am undergoing a definite learning curve on the care and feeding of this beastie, just like I did the SAP 180 almost 3 years ago.

Weird thing is, with my particular engine, there is no real warning...the engine doesn't pop or burp or nothing, it seems. Just decides to get going at some point after 100 flips. At home, on the bench, it started easily

I am going to get a heavy duty starter after all....

The pipe is an ESComposites 40G. Header is Hatori with an extension; distance to reflector from exhaust flange is 28". Prop is 18x12 MDK Hybrid, not apc, It is a wood/carbon composite that I make. RPM's not sure but by ear I think around 8K. The plane is around 10 1/2#. I had the SAP30cc in it before and it struggled on this prop...just too much for it. Lower rpm and couldn't pull a vertical without bogging down. The OS33GT is turning this same prop very well, putting out very useful power for the kind of flying (Masters Pattern) that I do.

But I'll see how it behaves later in the spring in warmer temp and higher humidity and after full break-in. Today it was 54F (fantastic for January) and low humidity.

telejojo

I don't flip anymore I got a 24v starter and save my energy for flying.

MTK

I absolutely hate starters. I've never had one; and I've never had any problem starting any of my engines by flipping. Glow 2 and 4 strokes and gas 2 strokes. The very easiest to start have been my Webra 145/160, SAP30cc, and DLE55cc. These are running in 3-4 flips and often on the first flip.

The OS has been a bear that way. I guess they said to start with a starter for a reason. No sense fighting city haul

airborne2.4

k4lm

Just ordered the GT33 for my Seagull 260 180.  I will be setting my timing to 28 degrees but I am not sure what spacer to use for the propeller.  Has anybody been able to order Vess props custom drilled?  I know that you can get Xoar custom drilled.  I would like to get a Vess 20A with an 8mm hole.

Vant

airborne2.4

Nice http://www.youtube.com/watch?v=GHPK-WvNyGo

k4lm

I received my GT33 and installed it on the Extra.  I have run two tanks (about 20 oz) through it.  I have the reverse running problem even with the sensor moved 1mm counter clockwise and opening the throttle some.  I have it adjusted to idle at 1800, but can't get WOT past 5400 rpm with an Xoar 18X8.  I am using 90 octane non-ethanol gas with 25:1 Sthil regular HD oil (orange bottle) not the synthentic yet.

What gives with the high end rpm???  I also noticed that in the article in Model Airplane News on the GT33 that his rpm/prop readings are off.
His Xoar 18X8 WOT was 9242 and the APC 18X8 was 8561.  After that, the rpm seems to drop.
 
APC 18X10   6838
APC 18X12   5414
APC 18X6W  5455
APC  20X10  4338

It doesn't look right to me. It looks like something changed during the test.  Any ideas?? I really do not want to send my motor in for service.

Vant

PlaneKrazee

My Feedback: (14)

WHat have you done to try to figure this out on your own or with other club members who run gas model engines?

Is this your first gas model engine?

Are you running with the cowl on or off?

Did you tune the carb with the cowl on?

Is the choke fully open?

The low end could be too lean.

Did you check with the high needle four turns open and full closed to see if it made a difference? You could have crap in the carb restricting flow. Do you have a Chainsaw type fuel filter in your fueling tank AND between your carb and the fueling port of the plane?

WHat are you running for ignition battery? Are you using a regulator? You could have a bad ignition. Get a spare from Wrong way rc AKA kava root for about $50.00.

Do you have a photo of the installation?

krlm, did you check the timing with a degree wheel? There are videos on youtube. You can also measure the timing with math. There are instructions on this site, I think in the FAQ section.

Do you have another prop to try like a APC 18X8W or a APV 19X8W?

PlaneKrazee

My Feedback: (14)

Double post

k4lm

For all of you that have checked their timing, tell me how you did it since the plug won't fire unless the rpm is above 160.  I was able to get a spark,but only when I was rotating the crank fast.  The video on timing is using an RCEXL ignition that will spark as the magnet leaves the sensor slowly. You can't do that on the GT33. 

Vant

bcchi

Hi Steve,
Bill Carpenter used to be C&H Ignitions.Have had to shut down C&H after 30 years due to Old age,health problems and cheap imports.There will still be a CH Ignition but I am out of it.I am still able going flying and do every chance I get. I have 20 gas engine airplanes ready to fly.I will have to try a OS 33 I am sure it is a fine engine,but I am not sure about the OS Ignition .The one I tested sparked at any RPM.I think they may be just telling us that so we will crank them at a good clip so the timing will retard.Plus this thing about the ignition telling you when the battery is low,heck they all do this.The engine will start to miss at full throttle but will give you plenty of time to throttle back and land and will probably come back with enought power to go around if you have to.
It sure looks like OS is using the RCEXL Igniton now.Good choice the RCEXL is the best Ign built and is exactly the same as my C&H except we used a much heavier spark coil.Xu Liang at RCEXL is a good friend,I have helped him and he has helped me.
He does have a change in the circuit that will make it more tolerant to voltage,will work 4.8 to 9 volts two Li Poli are OK no regulater.Our new ignition can be built for any voltage from 3.7 to 12 volts.I run my Ignitions now off my 6.6 volt Life flight pack,against my better judgement use Futaba Fasst radio do not do this with PPM(FM).
Funny thing Steve,I though Japan would grab my ignition many years ago but they never did untill the past few years and they build the poorest igntions out there.I do not have to tell you about a certain engine.
I am still flying the Fuji 86 that you gave me many years ago good engine when you change a certain part.Thank you we sold a lot of ignitions for the Fxxx engine.
I see Horizen jumped and the band wagon with the Zenoah engines and are going to the RCEXL ignitions.Good choice O,I said that.
Same thing Ralph and I have been doing for 30 years ,O well things move forward,I guess.
I have seven DL engines no problems except with the #4 Ign on the DL 20 has a screwey timing program but most fliers can not tell it is funny. This is not Xu Liangs fault this is what the engine people wanted,he noes it is not quite right.
I no some one that can still build ignitions so I snt all of my DL Ignitions to Ralph. They have not come close to Ed vollmers Syncro Spark for a computer timing control. They are no more I saved a few for myself and friends.
Hope you are well.
BCCHI
Youll never no how little I really care.

MTK

I saw that article too and was surprised at the low values the guy stated for moderate high loads.

I had an early break in my engine but after servicing, it has run well. I had to buy a starter for it but no big deal...

Mine is piped and therefore my numbers won't apply to a muffled engine but as a fun comparison, I get around 8K on an 18x12 wood-carbon hybrid of my design. I have also run the piped engine on a 20x10 ZDZ woodie and got around 6800 or so; pretty strong actually and the engine is not quite broken in (only have about 180 minutes/ dozen tanks through it)

The 18x12 works realy well on an 11 pound pattern model. It enables all the complicated maneuvers at half throttle...very sporty!

jnred123

Matt
Do you think it is a legit YS alternative for pattern, does it have that tractor like torque on uplines that the YS has.
What's it sound like with pipe.
Cheers
Greg
Australia

gibatta

My Feedback: (1)

Vant:

See the following link:

http://www.youtube.com/watch?v=EaYlG...eature=related

MTK

Greg,

I think this may very well be a good alternative to the YS 170. None of the other 30cc engines I've played with would haul the 18x12 hybrid prop without sagging; I've played with a few of them but certainly not all of them.
But I must qualify that statement by saying that it has only been run in cooler weather, between 50F and 65 F. It's too new to know how it will run in 95F weather next summer.

If my SAP180 is any indication tho, there was only a minor difference between cool and hot running. I'll have my answer next summer

Sound on pipe is similar to many other glow 2 strokes of this size on pipe. Perhaps a little louder but that may be as much the prop (my design) as anything else. I also have a 20x10 2 blade and an 18x10 3 blade wood-carbon hybrid in the works. I expect the 3 blade to be quietest. I think Mezjlik makes a good 18x10 3 blade too

A 19x11 2 blade apc should also be fairly quiet, except it is heavy

Almost forgot...the shake of the OS is considerably less than that of the YS 4 stroke. And a 14 ounce tank last around 18 minutes of pattern style flying (1/2-2/3rds throttle)...Hope that helps

jnred123

Matt
Thanks that does help, sounds pretty good might be worth a try.
The only one I've played with is a thing called a PTE36 which is a rear exhaust 36cc Chinese jigger, only had about 20 flights on it and it went OK on the standard muffler but I am about to try it with a mvvs tuned pipe in a better airframe but it sounds like the OS might be a bit stronger and would be better built I guess as well.
Cheers
Greg

airborne2.4

That's a real shakedown lol

PlaneKrazee

My Feedback: (14)

That's a good running engine in that video! And a beautiful plane.

wyo69cowboy

My Feedback: (2)

No doubt! Excellent throttle response; he's a real "throttle blipper" lol. Great flying!

airborne2.4

Can any of you guys make out what knid fo pipe he's using?

CustomPC

Most likely a Hatori Pipe

http://www.hatori-models.co.jp/HP3/air-e.html

airborne2.4

Thanks

airborne2.4

Thanks

MTK

Not a piped set-up. Too loud and harsh sound.

Sounds like the original muffler