Originally Posted by
Doug Cronkhite
The small gas engines have always been a bit tempermental for me. I flew the 3W 26, and while it put out a lot of power for its size, it was a pain to setup and manage. Clearly the smaller gas engines have come of age though, and it sounds like the OS 33 is a great choice.
Oh, and don't confuse a lack of response on your thread for a lack of interest. I've been following your threads for some time now, but haven't felt a need to comment as I wouldn't be adding anything to the discussion.
Thanks!
Just commissioned the second GT33 this weekend. Identical set-up as in my Aesthesis....ESComposites 40G pipe, own soft mount, avgas / Bel Ray MC1 at 50:1 ratio. The only difference is the header. I am using a steel flex header in the latest set-up in my Delta from Mile High RC, that was hand bent to return the exhaust to center. Cost is only around 25$ so less than 1/3 the cost of the Hatori RTC header. The steel header is very thin walled (lighter than the Hatori aluminum unit, so it's almost too thin) and a little too flexible. I will probably wrap the convolutions with glass to stiffen it a bit.
On the business side, same character as the first engine in Aesthesis. I have an 18.5 x 9.5 wide apc (courtesy of DinoP) on it right now for break in. The set-up is very quiet in my Delta. Delta, at 10 lbs 3 ozs, is about 1 1/4 pounds lighter than Aesthesis so you can imagine what performance is like.....Just need to get a bunch of break in flights over the next couple weeks. The synthetic oil is extremely effective since it takes a good 4 gallons to fully break in. My set-up is as simple as it gets: same fuel mix for break in as regular running. Change to the regular flight prop after two gallons on the break in prop. That's about it.
BTW- the first engine is on original everything. Same plug, same couplers, same mount rubber, same ring, carb, piston and bearings of couirse. Zero maintenance (after the early factory defect was fixed at 4 flights). Just over 40 gallons through it, over 100 hours of running, closing in on 500 flights. The built in protection of Avgas has possibly helped.
There are two things OS could do to improve on this powerplant: Offer a more linear carb, possibly rotating barrel type, than the current Walbro. Offer the engine in rear exhaust configuration. Neither of these things has been an obstacle of course. These things would simplify an already simple set-up even more, if geared directly at pattern and not Sport. Oh yeah, and get rid of the clunky looking muffler and save us 50 bucks.
EDIT--- The header from Mile High RC was too flexible and fatigued in 5 runs. Dunno, it might work better on a hard mounted engine but mine are all soft mounted so the steel header is toast. Back to Hatori