25cc Enough Power For 20lb Plane
03-25-2002, 04:42 PM
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25cc Enough Power For 20lb Plane
JUST WONDERING OTHERS THOUGHTS.
I'M BUILDING A SCRATCH BUILT OWN DESIGN GIANT SCALE PLANE. I HAVE A US ENG 25CC GAS MOTOR LAYING AROUND. AFTER I MOUNTED IT THE PLANE WEIGHED JUST UNDER 20 LBS.
IS THIS GOING TO BE ENOUGH POWER? I DONT NEED/WANT UNLIMITED VERTICAL OR ANYTHING OF THE SORT, JUST SOMETHING TO FLY THIS AROUND THE SKY AND NOT DRAG IT.
I PLANE ON USING A 16/8 PROP WITH THE MOTOR. I'VE ALSO THOUGHT ABOUT A 180 2 STROKE.
ANY THOUGHTS WELCOME.
THANKS
TOM
I'M BUILDING A SCRATCH BUILT OWN DESIGN GIANT SCALE PLANE. I HAVE A US ENG 25CC GAS MOTOR LAYING AROUND. AFTER I MOUNTED IT THE PLANE WEIGHED JUST UNDER 20 LBS.
IS THIS GOING TO BE ENOUGH POWER? I DONT NEED/WANT UNLIMITED VERTICAL OR ANYTHING OF THE SORT, JUST SOMETHING TO FLY THIS AROUND THE SKY AND NOT DRAG IT.
I PLANE ON USING A 16/8 PROP WITH THE MOTOR. I'VE ALSO THOUGHT ABOUT A 180 2 STROKE.
ANY THOUGHTS WELCOME.
THANKS
TOM
03-25-2002, 07:23 PM
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Tooo small
Tom,
It will be fine if you want to taxi around on the runway
. Just kidding. That would be too small to pull you out of trouble, if the airplane gets into a stalled state. Also, your takeoff angle would be severely shallow. Performance would be greatly limited. I don't think I would risk a 20lb airplane becoming a 20lb lawn dart.
Steve
It will be fine if you want to taxi around on the runway
. Just kidding. That would be too small to pull you out of trouble, if the airplane gets into a stalled state. Also, your takeoff angle would be severely shallow. Performance would be greatly limited. I don't think I would risk a 20lb airplane becoming a 20lb lawn dart.Steve
03-25-2002, 07:32 PM
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25cc Enough Power For 20lb Plane
Tom:
We need to have other info.
Is it high or low wing ?
What shape is the airfoil ? Flat btm. semi or fully sym.
Were you able to get close to the cg so it wouldn't have nose wt.?
If you built a 20# cub with the flat btm. wing and a 9' span, the
25 cc would just barely fly it. The wing area and type of lift will
be a factor. If it's a low wing, I would say no way.
We need to have other info.
Is it high or low wing ?
What shape is the airfoil ? Flat btm. semi or fully sym.
Were you able to get close to the cg so it wouldn't have nose wt.?
If you built a 20# cub with the flat btm. wing and a 9' span, the
25 cc would just barely fly it. The wing area and type of lift will
be a factor. If it's a low wing, I would say no way.
03-25-2002, 07:52 PM
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25CC POWER
IT IS A LOW WING. AIRFOIL IS EPPLER 197, NOT QUITE FLAT BOTTOMED BUT CLOSE. IT DID BALANCE OUT WITH THE GAS ENG.
INSTALLED. I THOUGHT ABOUT A 180 2 STROKE. IT'S ABOUT 2 LBS LIGHTER BUT ALSO PUTS OUT ABOUT 5.5 HP COMPARED TO ABOUT 2 THAT THE GAS ENGINE. WHAT DO YOU GUYS THINK ABOUT THAT?
THANKS FOR ALL THE REPSONSES.
TOM
INSTALLED. I THOUGHT ABOUT A 180 2 STROKE. IT'S ABOUT 2 LBS LIGHTER BUT ALSO PUTS OUT ABOUT 5.5 HP COMPARED TO ABOUT 2 THAT THE GAS ENGINE. WHAT DO YOU GUYS THINK ABOUT THAT?
THANKS FOR ALL THE REPSONSES.
TOM
03-25-2002, 08:06 PM
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25cc Enough Power For 20lb Plane
Tom:
You're still going to have to put the 2 lbs. back in the nose to get
the cg. Even though the 1.8 is lighter, it has to make up for the
tails weight.
A friend has a giant stinger with a S/T 3000 on it but it weighs
about 13 lbs. and the engine pulls it fine. This is working with big
wing area and lighter wt.
You're still going to have to put the 2 lbs. back in the nose to get
the cg. Even though the 1.8 is lighter, it has to make up for the
tails weight.
A friend has a giant stinger with a S/T 3000 on it but it weighs
about 13 lbs. and the engine pulls it fine. This is working with big
wing area and lighter wt.
03-25-2002, 08:48 PM
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25cc Enough Power For 20lb Plane
The US 25cc is a 4.5lb engine (according to their website). Personally, I'd sell it here or on ebay and look seriously at the 2.4 to 3.6 (40-60cc) gassers from ZDZ, Taurus, BME, 3W, etc. Even a Zenoah G-38 comes in at that weight.
You could put a big glow-puker in it if you wanted... assuming you own stock in a glow-fuel company and actually enjoy cleaning up the mess!
You could put a big glow-puker in it if you wanted... assuming you own stock in a glow-fuel company and actually enjoy cleaning up the mess!
03-25-2002, 09:41 PM
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25cc Enough Power For 20lb Plane
What 180 2-stroke engine puts out 5.5hp?
I have a Moki 180 and it puts out 4.1hp. I have an OS FX 1.60 and it puts out 3.7hp.
Roger on the 25cc being way too small for any 20lb airplane, regardless of the wing loading, unless, of course, its just a very large glider that you need power to get airborne with.
I have a Moki 180 and it puts out 4.1hp. I have an OS FX 1.60 and it puts out 3.7hp.
Roger on the 25cc being way too small for any 20lb airplane, regardless of the wing loading, unless, of course, its just a very large glider that you need power to get airborne with.
03-25-2002, 09:42 PM
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25CC POWER
THANKS FOR ALL THE INPUT. I DID FORGET TO MENTION IT DOES HAVE JUST OVER 1800 SQ IN OF WING AREA (20.5" CHORD BY 92" SPAN). SO DO YOU THINK THAT'LL MAKE A DIFERENCE?
tOM
tOM
03-26-2002, 12:06 AM
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25cc Enough Power For 20lb Plane
While that has enough squares to fly fine at 20lbs (a wing loading of ~25oz/sqft)... its no glider.
Would 25cc's fly it? Maybe... maybe not. I tend to agree with Steve that it would be fine for taxiing. Will it have anywhere near enough power to get you out of even a little bit of trouble... no way. Will it have enough power to be a fun airplane to fly... not a chance. I'll stick with my initial recommendation.
Would 25cc's fly it? Maybe... maybe not. I tend to agree with Steve that it would be fine for taxiing.
Will it have anywhere near enough power to get you out of even a little bit of trouble... no way. Will it have enough power to be a fun airplane to fly... not a chance. I'll stick with my initial recommendation.
03-26-2002, 12:31 AM
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25cc Enough Power For 20lb Plane
No Tom, I was hoping you were going to tell us that there was a
US 41 or G-45 on the shelf with that 25 size motor.
You're better off going with a H-9 100" Cub arf for the 25 or 1.8 then getting the bigger motor for your scratch built. You'd have
trouble getting your plane off the ground with either motor.
US 41 or G-45 on the shelf with that 25 size motor.
You're better off going with a H-9 100" Cub arf for the 25 or 1.8 then getting the bigger motor for your scratch built. You'd have
trouble getting your plane off the ground with either motor.
