RE: OS 33GT Gasoline Engine for Pattern
 

You are most welcome Bob....Welcome to pattern and if I can assist you with anything, please contact me directly.

RE: OS 33GT Gasoline Engine for Pattern
 

Thank you Freddy.

I like the 33GT enough to buy a few more of them. Just as they did with the 140RX and 160FX, I suspect they'll increase the price just as soon as they can. This one is easily at the top of the heap of the 30cc class of engines, and in my view, puts out similar output to the benchmark YS170 or just a bit more.

RE: OS 33GT Gasoline Engine for Pattern
 

Deat MattK
You are going to close this thead.
I admire you on your passionated trials for F3A planes powered with gas engines. It ends up with successful results. I believe many F3A fliers will construct their F3A plane with gas engines. I am one of them, I am now much encouraged than ever before, manys were doubt, when you initiated your thread. Even you close this thread, I will keep looking on your other threads. Thanks again.

RE: OS 33GT Gasoline Engine for Pattern
 

Hello Matt

Great thread.

Friends of mine are going to build planes with gas engine.
Philippe built a Partner with a DLE30 (see pics), Grégory is building an Harmonie with a PT36R, Alain and Julian are building Passion with a DLE30, Temptation of Stéphane is equiped with a RCGF 32, Eric put a RCGF 32 in his plane
Claude

RE: OS 33GT Gasoline Engine for Pattern
 

matt

do you have some rpm numbers please on the APC19x11? and any results on the 3 blader ?

RE: OS 33GT Gasoline Engine for Pattern
 

Claude,

Thank you....Who makes that header?

Hatori wants about 75$ US fo the header I show in my photos, which is 1/3 the price of carbon pipe. And it still needs an extension

RE: OS 33GT Gasoline Engine for Pattern
 

Clivemc,

From post 222:

**I finally got a few numbers using my brand new TNC tach. I checked the engine's low end, mid throttle where I fly normally, and top end. I got the following:

Low end was reliable (19x11 apc 2 blade) down to 1750; engine only has 1 gallon through it so far so this may get a little lower, but it is low enough. Sounded like a YS 170 on low throttle...very neat sound

Half throttle stick, same prop, gave me approximately 6575-6780. Temptress will do everything in Masters pattern at half throttle

Full 7450-7600 average; The tach also records the hi or peak values and at full throttle the engine would occasionally hit 7800. So full throttle gives me an average of around 800 rpm more; that's what I have in reserve. Now I know why the engine drives Temptress to ballistic speeds.

Acceleration is instant even with this large load up front but it was 41 degrees today so cooling was not a factor. I leaned the low end needle a hair and it helped a little bit. How it does in warmer weather waits to be experienced **


I wrote that piece when the engine was still breaking in. Engine now has over 3 gallons through (about 40 flights) it and is considered fully broken in.

The 3 blade 18x10 Mezj spools to 7550-7650. The engine is happy turning this prop or the 19x11 apc. Terrific power in the air and quiet with either prop. The 3 blade prop produces a sound similar to what the apc 15.75x11 3 blader produced a few years ago

My MDK 20x10 hybrid also is very quiet and it turns at 7350. It has a wider blade area than the 19x11 hence just a bit more load. But the OS just runs the load and doesn't seems to get lugged down. It is quite impressive in its ability to turn such a load for only a marginal increase in displacement (and weight) over the 30cc engines available today

RE: OS 33GT Gasoline Engine for Pattern
 

Choihjin,

Thank you....Please don't misunderstand. I can't close the thread and intend to post here from time to time as new things develop. What I'm saying is that the experiment was successful and is at a good resting spot, even with my early problems I alone experienced. I have not heard anyone else complaining about broken engine parts out of the box.

I want to try to clean up the mid throttle richness some more, but that may not happen this year. I also want to use a different, much less expensive pipe than the ESComposites. I have the Mintor 38 aluminum pipe I want to take a look at soon.....

It's time to fly the set-up as much as possible, to fully wring it out

RE: OS 33GT Gasoline Engine for Pattern
 

Hello Matt

Philippe answered me. He bought at Intermodel :
http://www.intermodel.fr/echappement...-20-30cc-.html

Other :
http://www.sdshobby.net/new-designed...ne-p-3800.html

Claude

RE: OS 33GT Gasoline Engine for Pattern
 

Canister Muffler at VVRC;)
http://www.valleyviewrc.com/estore/c...-dle-30cc.html

RE: OS 33GT Gasoline Engine for Pattern
 

Here is a larger assortment of headers and mufflers.  The flex style may be useful for some applications.  These folks ship fast. Bob

http://milehighrc.com/muffler.html

RE: OS 33GT Gasoline Engine for Pattern
 

Added to my favorites;)

RE: OS 33GT Gasoline Engine for Pattern
 

Thanks Bob, good to know a decent source. The headers look like they are steel. Do you know weights?

The Hatori ally header and extension weighs in at 3 1/2 ozs for the 33GT. The steel DA header for the DLE55 weighs 4 1/2 ozs. If the shown headers weigh about the same, they will work well

RE: OS 33GT Gasoline Engine for Pattern
 

I've been running the DLE20 in a 1.10 class TWM SPot on all of last year. I retired the airframe the beginning of this year to fit it into a H9 SHowtime 90. THe Spot on was simply poorly constructed and after a few mishaps showed age and an marked increase in weight.<div>
</div><div>The DLE 20 provides fantastic throttle responce and instant spool up on an APC 17x6. I've run various pipes as well and am achieving 8400rpm on the ground with a canister.</div><div>
</div><div>My next gasser Pattern plane project will be an Evolution with the Mintor 38 on pipe. The OS GT33 is the back up plan.</div><div>
</div><div>I don't think theres going to be many petrol pattern planes at the Worlds in 2013 (to be held at 1600m above sea level) but I believe it will become more widely accepted thereafter.</div>

RE: OS 33GT Gasoline Engine for Pattern
 

I believe that at some point, folks will look at gasoline as an alternative at top level competition......I think there is quite a bit of room since glow is about 5X more expensive (annualized, per pattern schedule) and E-power about 6X (current set-ups and battery costs, and again per schedule basis). There is some more work to be done with exhaust systems and props to keep things quiet and generate even more thrust

The big assumption is that folks like OS will continue to improve their products for our needs and others will enter the same market to keep prices in check (YS, DA? one can only hope)....

Current electric set-ups are very tough competitors on the power side, for precisely the size model we fly. The biggest detriment to me is the fact that you fly one schedule and must land, and then have to do some "refueling" gyrations to support your batteries. People have learned to minimize that pain.

My e-power friends continue to argue that electric forces you to make better decisions in flight and avoid the need to "go around". There might be something to that....But I don't feel I fly more sloppy because I can with gas. I would with electric too. LOL!

RE: OS 33GT Gasoline Engine for Pattern
 

Mid throttle richness with my MT 70 was corrected with lighter prop load. I was able to lean the high end which in turn cleaned the midrange.

RE: OS 33GT Gasoline Engine for Pattern
 

I ran out of Avgas and decided to use 93 octane premium unleaded auto gas for a couple gallons. Today was the maiden flight with autogas and I must say it was less than stellar. The engine ran fat and never cleared up. Needles need to be tweaked but it was extremely windy and gusty and I never did tune the engine fully to my satisfaction.

Premium is not as stinky as regular and is actually pallatable. I may change for good since getting Avgas is not as simple as it was before. I no longer fly out of a side lot of an airport as I did previously

RE: OS 33GT Gasoline Engine for Pattern
 

Matt,

Using avgas has benefits, for one the smell is not bad and for another the stuff lasts and lasts with no worries about residue that is so common with mogas. Make the trip and pay a little extra for the avgas and in the long haul you will not be disappointed. That is as long as it is available.

Mike

RE: OS 33GT Gasoline Engine for Pattern
 

what prop were you running and what did you switch to? usually if you dont load it enough you get mid range burbling and by upping the prop / load you can get it to tune and run better.....

RE: OS 33GT Gasoline Engine for Pattern
 

Went from a Zoar 23X8 laminated to a Mejzlik 22X8.

RE: OS 33GT Gasoline Engine for Pattern
 

Retuned the engine for premium autogas. Surprised to find a considerable bump in power output over Avgas. The engine is pretty well broken in so the numbers I am getting now should be a bit better than a couple months back, but still this much was unexpected....

18x10 3 blade Mezjlik, 8150-8200 rpm at full revs, 7400 at mid throttle where I fly (Avgas ran about 7700)
20x10 MDK Hybrid, 7920-7950 rpm at full revs, 7150 at mid throttle where I fly (Avgas ran about 7400)

These are steady state numbers. The TNC tach also has a peak rpm feature; these were not peak numbers

Just received 19x12, 19x13, 20x12 and 20x13 Xoar electric wood blanks to be laminated into MDK Hybrids. I'll have numbers in due course.

RE: OS 33GT Gasoline Engine for Pattern
 

Hi Matt, how many layers of what are you going to put on the propellers?

RE: OS 33GT Gasoline Engine for Pattern
 

The bump in power should not be surprising. AVGAS is slower burning due to the amount of TEL. IF that was removed the flame front would burn faster, probably too fast for a slow reving 2 stroke to see the benefit but it would help it maximise its potential on the curren tune. Pipes, more aggressive jetting and porting would yield even more power.
There are some 4 stroke racing engines that useethanol to an advantage they can change the transition from lean to rish and back again at different loads to optimise the power band i.e. broaden it to improve acceleration and top end.
With some development of our little petrol engines I'm pretty sure we will see significant improvements in the exploitation of E10 through clever timing curves, more agressive porting and dedicated pipes
<br type="_moz" />

RE: OS 33GT Gasoline Engine for Pattern
 

Roberto B.

I use 3K braid for the reinforcement. I start with a center piece which covers about 2" either side of center, and finish with single tubes on each blade starting from the knuckle. The area around the start of each blade has two layers in other words; single layer everywhere else.

I use epoxy on the carbon sock and then vacuum bag the whole assembly.

The process really starts by first heat forming two sets of polyester plastic blade "molds" that surround each blade. This is as simple as cutting the sheet to shape and forming around each blade with a monokote heat gun. The carbon-epoxy covered propeller is inserted into these "molds" and secured. One of these days I may get around to writing a full description and publishing in MAN or MA.

The prop is removed from the mold and finished, polished, balanced. I'll take a snap tonight and post. I also have MDK props shown in the SAP180 for Pattern thread.

Oh yeah, the wood blanks are Xoar electric woodies of proper diameter and pitch. I reshape the electric blades for gasoline and thin them even more to accommodate the carbon sock. The hub of the electric props in not wide enough for a multi bolt propeller installation but the OS has a single nut installation, ideal for my props. For multi bolt mounting, the prop hub is widened first with maple

The 20x10 MDK prop weighs 74 grams, on par with first generation electric carbon props....but of course it is used in a gasoline application.....It is a true "stressed skin" laminate

RE: OS 33GT Gasoline Engine for Pattern
 

I have the 19x13 laminated and am in process of balancing. That's looks like quite a bit of prop and it is, but I think the OS will handle it. I need to bring rpm down to 7100 give or take to get the sound really down.

I will post numbers when I get them later this week. The 19x13 is also a XOAR electric woodie, reshaped to an apc style profile and laminated with carbon sock. If I remember I'll post some photos of the molding plates