wyo69cowboy

My Feedback: (2)

Very nice sound/tone to it! Thanks for posting...

TimBle

flies beautifully!

MTK

NO, no...not the flying. Was trying to convey the fact that gas engines in this displacement size up to 60cc give or take. don't have to sound like chain saws. There are off the shelf items one can use to knock out much of the noise and annoyance factors.

Always flying

My Feedback: (22)

has anyone run a header and pipe with this engine?...would like info on header length and prop combo...thx fellas'

rstekeur

I'm building a Kangke 72" Waco bipe which should come in around 14lbs. I was thinking about a dle 35ra for the motor which is on back order till mid jan or the os 33. I'm not looking for 3d performance some areobatics. I like the single hole for the prop and OS has a good name. I just wonder if the OS33 is going to be enough for this plane.  

john josey

I have my 33 in an 11lb yak 54 and it has unlimited vertical at half stick ! At full throttle it just goes vertical much much quicker.

MTK

It will give your model all the power it needs plus quite a bit more

rstekeur

Thanks MTK, are you talking about the OS GT33?

choihjin

My Feedback: (1)

Dear MattK
Nice to see you and your successful gas-powered F3A plane. I was very curious about you who is very talented in making all kind of hardwares, such as hand-made carbon props, exhaust pipe, soft-mount, plane itself...
I wondered who you are. I just met you in the you-tube. Thank a lot for your posting the video.
Wish you happy new year and all of you in this forum too.
Best Regards

MTK

Choijin....My friend Auggie Scafidi posted the video since I haven't tried to figure out how to do that yet. The hobby gives me a great avenue for creation and release of ideas. I do what I do as matter of course. Then I post my findings, free of charge, for anyone to copy. So far,a few brave souls have tried some thingssuccessfully....Thank you for the ackowledgement !!

seagull extra

My Feedback: (12)

I just bought a 33 today. I am planning to use it in a 78" extra 300 that will likely weigh in at about 13.5 lbs. Does anybody have any prop no's for a 20"x8" prop?

MTK

Somewhere around 7300 I'd guess, or a bit more on muffler. Let me put it this way, Mine is piped and turning a 20x10.5 APC at 7400 (Avgas mixed50:1 with Bel Ray MC1), and around 7750 on premium autogas.

Engine is putting outover 24 lbs of thrust at full revs, so maybe that will be closer to 20-22 lbs on muffler.

I use a Dynatron to start it. It hand starts fine but takes a little more flipping than I want. Dynatron starts are simple, making this chore easy

ghoffman

My Feedback: (3)

What pipe Matt?

MTK

Same as yours Gary, ESComposites 40G carbon. You wanna hear something sweet, take a look at my video...

seagull extra

My Feedback: (12)

Thanks for the reply Matt. I did notice that you were getting some good prop no's with your pipe. I was hoping to get some first hand prop no's with the stock muffler as that is what I will be using. If it can do 7000rpm with say a 20x8 xroar prop I should be okay. Like I said my plane will be at least 13.5 lbs possibly 14lbs so I know I'm getting to the upper limit for weight for this motor.

ghoffman

My Feedback: (3)

Nice! How is the sound without the exhaust exit device?

MTK

It's the same as far as dB go. But to the ear, the sound is very slightly different, mellower with the gizmo on.

An earlier experiment, before the diffuser, accomplished the same thing as the diffuser by reducing the stinger cross section to 5/16", so I think it has more to do with the exhaust stinger cross section than it does with diffusing the exhaust.

Final word on that hasn't been written yet as the R&D continues. I've come up with something different for the exhaust but that will have to wait til Spring...

I should have a different plane by then too to try the piped OS in.

ghoffman

My Feedback: (3)

What dB at 20 feet is it?  

MTK

The XOAR props are a little more load than APC's because of the widerand thickerblades. If you aren't happy with the results, don't fret it. Get an APC prop from Central Hobbies. They are heavier props than the wood but are more efficient and work exceptionally well in suppressing noise. Remember, if you can hear the prop it means power is taken from thrust and being converted to noise

I think you said a 78" Extra. I know of the Extreme Flight 78" Extra. That model is very light and the OS is perfectly suited to it

MTK

Hmmmmm... Dunno! It's around 92-93 at 10 feet over grass.

I would guess around 88-89 at 20 feet over grass. Probably 90 over asphalt

Who sez you can't quiet a gassie??

BarracudaHockey

My Feedback: (11)

I think that engine would be perfect on the EF 78" Extra.

I just got one to review thats going on a 70 Fokker DVII but when I'm done with the review I'll be looking for an aerobat for it and may get another Extra (I had one before that I used to test a couple of the MLD engines on)

ghoffman

My Feedback: (3)

Yes, that is what I am thinking, and since I have the pipe, all I would need is the header.  However, I am going to try the M38 we got back from service and try it since I have it, the header and the ES40G pipe. By then, the WRAM show will have happened and I will have an idea if the DA-35 will ever come out.

MTK

I had the M38 and tried it with the Mintor pipe and the ESC 40G. It isn't in the same league as the OS, powerwise.

But it is a nice sport engine with very good field manners. I sold mine to a sport flier

Broken Wings

My Feedback: (20)

I "saved up" and bought one of these engines. It looks pretty nice. I have a Macs Products #1096 Quiet Tuned Pipe that is 25" long. I ordered the header pipe for this engine from Macs as well.

Does anyone know what the length from the spark plug to the first baffle in the pipe should be?

coronabob

My Feedback: (10)

Flew my GT33 for the first time today. Started easily and I knew how to avoid the backward running thanks to this post. No break in on the ground, Xoar 20x8 on a Great Planes Yak with factory settings I got 6,400. The plane went vertical at a constant speed at less than WOT. It was very quiet in the air as I could barely hear it with someone running their engine on the ground. It idled very well below 1800, accelerated w/no burble. I am very very pleased with it.