Engine Choice, for small Twin? 25's?
10-08-2011, 11:03 AM
#1
Thread Starter
Engine Choice, for small Twin? 25's?
I'm researching engine choices for a small twin.
I have one, NIB GMS 25, but they spin small props, 8x6.
I would consider a couple of small 4 strokes.
I know nothing about and have had no experience with engines under .40.
Thanks in advance.
Charles
I have one, NIB GMS 25, but they spin small props, 8x6.
I would consider a couple of small 4 strokes.
I know nothing about and have had no experience with engines under .40.
Thanks in advance.
Charles
10-08-2011, 12:17 PM
#2
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RE: Engine Choice, for small Twin? 25's?
The biggest killer of twins is a "engine out", I always use a "on-board glow driver" system, home made and all the rudder I can get.
Smallest set of twins I've used is Thunder Tiger 36's.
Never cheap-out on glow plugs, I use fuel with synthetic oil and 15% nitro, 10% in cold weather.
Chuck
Smallest set of twins I've used is Thunder Tiger 36's.
Never cheap-out on glow plugs, I use fuel with synthetic oil and 15% nitro, 10% in cold weather.
Chuck
10-08-2011, 12:27 PM
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RE: Engine Choice, for small Twin? 25's?
There are also two camps with twins
Lets take a 60 size single engine plane, 72" wing span and 7 pounds and make a twin out of it.
Engine choice
Camp 1 says put two 60's on it and throttle back some so you don't rip the wings off. You have full power and can still fly with an engine out.
Camp 2 says put two 30's on it so you have a lighter weight plane that uses less fuel. Engine out your coming down though.
Then there what to do with an engine out.
A Cut off the live engine and come in dead stick.
B Keep speed up with the live engine and come in hot at 75% power.
Sims let you play around and find out which way works best for you.
Lets take a 60 size single engine plane, 72" wing span and 7 pounds and make a twin out of it.
Engine choice
Camp 1 says put two 60's on it and throttle back some so you don't rip the wings off. You have full power and can still fly with an engine out.
Camp 2 says put two 30's on it so you have a lighter weight plane that uses less fuel. Engine out your coming down though.
Then there what to do with an engine out.
A Cut off the live engine and come in dead stick.
B Keep speed up with the live engine and come in hot at 75% power.
Sims let you play around and find out which way works best for you.
10-08-2011, 02:39 PM
#6
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RE: Engine Choice, for small Twin? 25's?
Three Hobbico Twin Stars, one with OS-40 FP engines, one with Thunder Tiger 36 engines and the third was a volter with Axi 2820-10 motors.
Ace Sea Master with T.T. 36's. Usta be pics here on RCU somewhere.
Gemini Twin with T.T. 36's.
60 size trainer with OS 50-FX engines and a camcorder in the nose and heavily modified landing gear.
Urovich OV-10 with Axi 2820-10 motors.
10-08-2011, 03:07 PM
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RE: Engine Choice, for small Twin? 25's?
Charles the little guys [.07's to .35's] run the same as the .40's it's when you get down into the Cox/Norvel leval that things change some.
Give us some info on your project. Sport or scale? Weight? Wing Span? Fast or Slow flying?
I allways had good luck with the OS engines back in the day. I had a FP .15 and FP .25 engines and a .32SX
If you can swing the price Saito .30's would make a good choise.
As for two strokes I haven't tried OS's new LA serese. I don't like those rear needles at all on any engine.
http://www3.towerhobbies.com/cgi-bin...?&I=LXPUE0&P=7
The 25AX looks really nice but ouch $160! Your looking at $320 for two of them.
http://www3.towerhobbies.com/cgi-bin...?&I=LXXEG2&P=7
Magnum has the Magnum XLS-15A that looks intersting though I haven't seen the reviews on it.
http://www3.towerhobbies.com/cgi-bin...?&I=LXRLG6&P=7
The smallest Super Tigre is a .34 that puts out like alot of .40's
http://www3.towerhobbies.com/cgi-bin...?&I=LXFV68&P=7
Tunder Tiger's .07 looks cool but I've seen bad reviews on it.
K&B's small Sportsers don't have alot of power but they run well. Allways good for a twin.
http://www.mecoa.com/kb/aero/aircraft.htm
MECOA's little .15 is one wierd looking engine. I haven't seen reviews on it either.
http://www.mecoa.com/mecoa/15/1501.htm
The HP .25 4-stokes are $288 so you'd be looking at $576 to power a little airplane.
Give us some info on your project. Sport or scale? Weight? Wing Span? Fast or Slow flying?
I allways had good luck with the OS engines back in the day. I had a FP .15 and FP .25 engines and a .32SX
If you can swing the price Saito .30's would make a good choise.
As for two strokes I haven't tried OS's new LA serese. I don't like those rear needles at all on any engine.
http://www3.towerhobbies.com/cgi-bin...?&I=LXPUE0&P=7
The 25AX looks really nice but ouch $160! Your looking at $320 for two of them.
http://www3.towerhobbies.com/cgi-bin...?&I=LXXEG2&P=7
Magnum has the Magnum XLS-15A that looks intersting though I haven't seen the reviews on it.
http://www3.towerhobbies.com/cgi-bin...?&I=LXRLG6&P=7
The smallest Super Tigre is a .34 that puts out like alot of .40's
http://www3.towerhobbies.com/cgi-bin...?&I=LXFV68&P=7
Tunder Tiger's .07 looks cool but I've seen bad reviews on it.
K&B's small Sportsers don't have alot of power but they run well. Allways good for a twin.
http://www.mecoa.com/kb/aero/aircraft.htm
MECOA's little .15 is one wierd looking engine. I haven't seen reviews on it either.
http://www.mecoa.com/mecoa/15/1501.htm
The HP .25 4-stokes are $288 so you'd be looking at $576 to power a little airplane.
10-08-2011, 03:18 PM
#9
Thread Starter
RE: Engine Choice, for small Twin? 25's?
War,
Thanks for all that. plenty to digest, but the high end stuff, ouch!
The Saito 30's. Is that 4 stroke? Know anything about them?
The model is small, 51" in span. I'm thinking CL. It'll last longer.
Thanks for all that. plenty to digest, but the high end stuff, ouch!
The Saito 30's. Is that 4 stroke? Know anything about them?
The model is small, 51" in span. I'm thinking CL. It'll last longer.
10-08-2011, 03:25 PM
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RE: Engine Choice, for small Twin? 25's?
Sounds like .20's to me.
Find a pair of them you like then break them in and see how they run.
Find out how much power they are putting out then you can design your plane around that power and prop clearance [nacels and ground].
..and get rid of the strings man! Go RC or don't go!
Your either with us or your with the stingers!
I swear one day I'm going to build some solid oak models. Tie them to a rope and go out to the CL circle and sling them around!
Find a pair of them you like then break them in and see how they run.
Find out how much power they are putting out then you can design your plane around that power and prop clearance [nacels and ground].
..and get rid of the strings man! Go RC or don't go!
Your either with us or your with the stingers!
I swear one day I'm going to build some solid oak models. Tie them to a rope and go out to the CL circle and sling them around!
10-08-2011, 06:02 PM
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RE: Engine Choice, for small Twin? 25's?
When I convert a single engine plane to a twin I start by drawing a line on a work surface and laying the plane on the line. Mark where the prop is on the line mark where the tail fethers are, and put another mark on the line at the cord of the wing or the CG. Now put a mark at on the line at twice the distance of the mark for the cord or CG to the tail fethers further down the line. Use this mark to establish the the new thrust lines for each engine. The new engines should be no less than 2/3 the the max engine size and minimum engine size rated for the plane.
After taking off the old engine take a piece of string and tie it to the Two new engines hang them over the fuse. Place the planes wing on blocks and ballance by moving the string foreward or back to ballance. With this done align the engines and establish your thrust lines using half the prop size plus 3/4". By establishing these thrust lines your plane will be much easier to handle if one engine fails and by using enough but not to much engine you will still have a flyable airplane. when you loose an engine you dragging and anchor, so you have to have enough power to fly the plane and drag the anchor.
10-08-2011, 06:31 PM
#15
RE: Engine Choice, for small Twin? 25's?
Charles,,
IMO, you're crazy for wanting to convert that thing to 25 size glow,, especially four strokes ,, a pair of 15s and you'd be in the right prop range and the plane wont be crazy heavy,, the wing loading already is near 30 oz/ft on a plane under 400 sq.in. of wing. might want to modify it with flaps while you're at it
good luck
IMO, you're crazy for wanting to convert that thing to 25 size glow,, especially four strokes ,, a pair of 15s and you'd be in the right prop range and the plane wont be crazy heavy,, the wing loading already is near 30 oz/ft on a plane under 400 sq.in. of wing. might want to modify it with flaps while you're at it
good luck
10-09-2011, 12:32 AM
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RE: Engine Choice, for small Twin? 25's?
ORIGINAL: Avaiojet
I couldn't find info on Saito 30's
Nothing wrong with strings, I have a banjo also.
I couldn't find info on Saito 30's
Nothing wrong with strings, I have a banjo also.
LOL Yes the banjo is the official musical instrument for CL flyers, you have a circle and allot of strings.
You couldn't find any info on the Saito FA-30's? What is your source for info?
Here is the details,
http://www.horizonhobby.com/Products...rodID=SAIE030S
They have been discontinued so you have to find them used.
Also be careful because Saito has a new engine called the FG-30 that is a 30cc gasoline engine.
Here is a FA-30 on ebay right now.
http://www.ebay.com/itm/SAITO-FA-30s...item27bee2866e
10-09-2011, 01:00 AM
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RE: Engine Choice, for small Twin? 25's?
ORIGINAL: Carlos Murphy
If control line flyers play banjos... what do ukulele players fly???
If control line flyers play banjos... what do ukulele players fly???
http://www.youtube.com/watch?v=7z5wRbJJvDk
10-09-2011, 04:29 AM
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RE: Engine Choice, for small Twin? 25's?
BARF
ORIGINAL: AmishWarlord
Peanut Scale!
http://www.youtube.com/watch?v=7z5wRbJJvDk
ORIGINAL: Carlos Murphy
If control line flyers play banjos... what do ukulele players fly???
If control line flyers play banjos... what do ukulele players fly???
http://www.youtube.com/watch?v=7z5wRbJJvDk
10-09-2011, 05:27 AM
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RE: Engine Choice, for small Twin? 25's?
ORIGINAL: mike31
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10-09-2011, 05:47 AM
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RE: Engine Choice, for small Twin? 25's?
I have a Hobbico "Twin Star" that I bought just because I'd never flown a twin. Since I wanted to keep my investment minimal, I chose a pair of new OS .25 LAs and broke them in carefully before putting them on the plane. They allowed the plane to balance perfectly with no additional weight, and are more than ample power for any sport manuever.
I tach them at a matching 12,200 on 9/4 props before each flight and have had no problem with engine flame-outs. The built-in thrust angles should keep the plane flying if one does decide to quit. The plane is rock-solid in every respect and lands exceptionally easy. It has been an unexpected delight, and there's nothing quite like those twins singing in unison during a pass down the field.
I tach them at a matching 12,200 on 9/4 props before each flight and have had no problem with engine flame-outs. The built-in thrust angles should keep the plane flying if one does decide to quit. The plane is rock-solid in every respect and lands exceptionally easy. It has been an unexpected delight, and there's nothing quite like those twins singing in unison during a pass down the field.