need recommendation: giant scale 4-stroke
07-26-2005, 07:43 PM
#1
Thread Starter
need recommendation: giant scale 4-stroke
I'd like your recommendation on what 4-stroke glow engines can swing a 22x6 prop at least 6000rpm, preferably higher. Is this in the range of a Saito 150, a Saito 180, or higher? Or would an OS 120 suffice? I'm not calibrated for glow engines this size, since my prior experience in giant scale has only been with gas engines. As you know, gassers can be heavy & so I'm toying around with the idea of getting the airplane to still balance with a lighter glow engine.
Thanks!
Thanks!
07-26-2005, 08:14 PM
#3
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RE: need recommendation: giant scale 4-stroke
No disrespect, but a 22" prop and you're thinking a 120 may suffice? It takes a G62 which is 62cc's (or greater) to swing a prop like that. A 120 is only 20cc's and a 16" is about all they will swing.
I like the Laser 300V twin 4 stroke, it's only 50cc's but it will swing a 22" prop easily and they weigh half what a G62 does.
2 Piece
I like the Laser 300V twin 4 stroke, it's only 50cc's but it will swing a 22" prop easily and they weigh half what a G62 does.
2 Piece
07-27-2005, 12:41 AM
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RE: need recommendation: giant scale 4-stroke
What size plane are you going to fly with this combo?
How much does it weigh? Is it a scale flyer ? aerobatic? 3D?
How much does it weigh? Is it a scale flyer ? aerobatic? 3D?
07-27-2005, 08:48 AM
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RE: need recommendation: giant scale 4-stroke
As indicated above, Saito 220 will swing 20x8, I'd imagine in the mid 7k. Don't hold me to this figure. I am simply using correlation based on other props. Having said that, 22x6 will have about similar load as 20x8. But I am not sure who makes a 22x6. The Saito 220 might swing 22x8 @ 6000 rpm, but it will be struggling, overheating…
Moki 210 will swing 22x8 @ mid 7k, if you don't mind a 2-stroke. Also, there are light weight 50cc gas engines, like DA and BME. They both weigh about 3 lb w/o muffler, and will swing 22x8 easily.
Fuji has a gas 4-stroke, but it feels like a boat anchor. That thing is heaveeeey.
Moki 210 will swing 22x8 @ mid 7k, if you don't mind a 2-stroke. Also, there are light weight 50cc gas engines, like DA and BME. They both weigh about 3 lb w/o muffler, and will swing 22x8 easily.
Fuji has a gas 4-stroke, but it feels like a boat anchor. That thing is heaveeeey.
07-27-2005, 11:42 AM
#7
Thread Starter
RE: need recommendation: giant scale 4-stroke
The application is my 1/4 scale Nieuport 17, WWI model. I've currently got a US 41 gas engine on this and a Zinger 22x6 wooden prop. The dry weight of this combo is 16 lbs. This is a couple of pounds heavier than I'd like and in hot conditions, the landings are trickier with this much wing loading. I originally got the US 41 because that is the engine recommended for this design and with that engine mass, it does balance exactly per the plans. However, as I started to study CG placement more, I've learned that there is quite a lot of tolerance for moving the CG, I've heard as much as +/- 10% of the chord without catastrophic effects.
If I move the balance point back an inch, this has the dual benefit of reducing the tail's moment about the CG as well as increasing the engine's moment about the CG, which enables the use of a lighter engine.
Having said all this, the engine options available are fairly expensive & due to cost, I may just be better off living with my current arrangement.
If I move the balance point back an inch, this has the dual benefit of reducing the tail's moment about the CG as well as increasing the engine's moment about the CG, which enables the use of a lighter engine.
Having said all this, the engine options available are fairly expensive & due to cost, I may just be better off living with my current arrangement.
