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General control line discussion => Open Forum => Topic started by: Alex Givan on May 21, 2010, 07:40:25 AM
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As the T-Rex has been out for a little while now, and some of you Gent's have developed a good idea of what powerplant works best in this airplane. I would like to know what would be the minimum and maximum displacement range for a 2 stroke engine and the same for a 4 stroke.
Your engine choices along with what prop combination worked best I would like to hear about. Has anyone given the Fox Ceramic 60 a shot or Saito 72?
Also those of you that have this airplane is the issue of the fuselage cracks a solved problem or are further mods still required once you have the ARF or ARC in hand?
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Hey Alex,
Check out all the T Rex threads in the ARFs section of this forum for alot of details in structural items as well as the motors that have been employed so far. In brief, I would consider the ST-51 the absolute minimum power in a 'rex. I used the DS 60 with the Mezjlik 12.5 x 5.2 undercamber three blade to great effect. As far as four strokes, the Saito 56 is the smallest I know that somebody has used, and it has plenty of power for the T Rex. I assume the Fox 60 would work, but I have no idea how they run. The Saito 72 should work, but if it was me I would look at the threads regarding installing shear webs in the wings so the wings stay together under that power. y1
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Wing problems??? I thought that all the structural problems were with the fuselage. I guess I need to do more research.
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See this link:
http://stunthanger.com/smf/index.php?topic=16547.0
Its a little further down in the ARF section.
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As the T-Rex has been out for a little while now, and some of you Gent's have developed a good idea of what powerplant works best in this airplane. I would like to know what would be the minimum and maximum displacement range for a 2 stroke engine and the same for a 4 stroke. . . .
Alex --
You might want to avoid the "suck-squeeze-pop-phooey" engines considering who we fly with. Willis and Jimmy aren't all that far away, but nobody in our club field has the hands-on "tuning" expertise you need to get things right in the beginning.
There is no doubt that these engines are viable, or perhaps even superior, but being the only guy on the block with a four cycle is not the way I would recommend jumping into game.
Check the 4 stroke section here, and a quick scan of the threads tells you it is a different world.
Larry Fulwider
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Four strokes are not that hard to run. Yes they are different than a 2 stroke. They can swing a higher pitch at lower rpm and my experience is they will quit instead of burning down if set too lean. Over in the 4 stroke section there are several people well versed with 4 strokes, Bob Reeves comes to mind. If you do go with the big Fox let us know how it works. Myself, right now I limit myself to a .46 size plane. H^^
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The T-Rex (once the manufacturer completes structural upgrades) is under my consideration. At this time, I'm inclined to try either the Saito 62 or 72 ,depending upon the cg balance.
As others have pointed out, 4 strokes are quite user friendly and the rpms are consistent. I have used up to YS 140s in R/C pattern and a Saito 270 twin in IMAC without any issues other than routine bearing replacement.
It may be beneficial to soft mount them, but given the relatively small displacement of either Saito, it could be unnecessary and would definitely add more nose weight.
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Just get the Brodak electric turn key kit...
I ran a PA 65 on a muffler in my proto... Very smooth and easy to run.