Wee four-strokes and 1/2A definition
06-19-2003, 05:54 PM
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Wee four-strokes and 1/2A definition
Hi all, I'm back with more newbie questions! First, what defines a plane (or engine?) as being "1/2A"? Second, what are the smallest four-strokes that are commonly available, and who makes them? I really liked the sound of the 4-strokes that flew while I was out at the field. I can repost the second question to the engine forum, but thought y'all might know more about it than the typical crowd at the engines forum 
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06-19-2003, 06:19 PM
#2
Wee four-strokes and 1/2A definition
½A is the displacement of the engine.
Here are the engine classes.
Class---------Cubic inches
½A -----------0 to .049
A--------------0 to .200
B-------------.201 to .300
C-------------.301 to .650
OS used to make a .26 4-stroke, but the smallest I know of now is the OS .30 and the Saito .30.
Here are the engine classes.
Class---------Cubic inches
½A -----------0 to .049
A--------------0 to .200
B-------------.201 to .300
C-------------.301 to .650
OS used to make a .26 4-stroke, but the smallest I know of now is the OS .30 and the Saito .30.
06-19-2003, 06:36 PM
#3
Wee four-strokes and 1/2A definition
os also had a .20 before the .26 but that was ages ago. i think mecoa is still selling the HP (?) .21 roto-valve 4-strokes.
if you want itsy-bitsy 4- strokes look up george luhrs, i think he's made some smaller than .020 but i doubt he sells them.
dave
if you want itsy-bitsy 4- strokes look up george luhrs, i think he's made some smaller than .020 but i doubt he sells them.
dave
06-19-2003, 06:55 PM
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Wee four-strokes and 1/2A definition
Recently I think we've seen the 1/2A category expand to include the 061's at least for public recognition. For contest work it's still .050 for the cutoff.
I've got an OS .20 NIB never been run.... yet.... and it's MINE....ALL mine
I've got an OS .20 NIB never been run.... yet.... and it's MINE....ALL mine
06-19-2003, 07:05 PM
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Wee four-strokes and 1/2A definition
My vote goes to the HP VT .21. I had mine on a 6' old-timer and it was a simply awesome match-up. It was a LIGHT old-timer, though.
I think the 4-stroke question wasn't really intended for the "world's smallest" 4-stroke. In general, 4-stroke 20's are as small as they commonly went, and I don't think they even make that size anymore. I think new, commonly-available engines go down to about .26.......
1/2A flyers are a breed unto themselves, as evidenced by this standalone forum for those (us) guys. The littler they are, the tweakier they are, in general. F'r instance, I had a cheesey 1/2A control line plane powered with a "let's see what I have in the parts drawer" Cox .049. While it ran well, it continuously wanted to start and run in reverse....... You'd have to stop the danged thing and restart. Unless, like me, you have a pusher prop in the box "It wants to run backwards? So be it"
I think the 4-stroke question wasn't really intended for the "world's smallest" 4-stroke. In general, 4-stroke 20's are as small as they commonly went, and I don't think they even make that size anymore. I think new, commonly-available engines go down to about .26.......
1/2A flyers are a breed unto themselves, as evidenced by this standalone forum for those (us) guys. The littler they are, the tweakier they are, in general. F'r instance, I had a cheesey 1/2A control line plane powered with a "let's see what I have in the parts drawer" Cox .049. While it ran well, it continuously wanted to start and run in reverse....... You'd have to stop the danged thing and restart. Unless, like me, you have a pusher prop in the box
"It wants to run backwards? So be it"
