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2 stroke for 3d?

Old 11-14-2004, 05:17 PM
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Default 2 stroke for 3d?

Hello fellow modelers.

I got question.Is it true that 4 stroke is preferable for 3d flying and 2 stroke just won't have that torque?
What if i play with lower pitch props?
Wondering about that........

Mitty
Old 11-14-2004, 05:53 PM
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Default RE: 2 stroke for 3d?

If you're talking a 4 1/2-5 pound plane a 46 fx with a 12.25x3.75 apc will work as a great combo. That prop is a great 3D prop for all 46-52 size 2-strokes.

Have fun Mattflyer!!!!!
Old 11-14-2004, 07:26 PM
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Default RE: 2 stroke for 3d?

In the 40 size category, both work well. I have both but my personal preference is with the 4 strokers. I have a YS63 on a Burrito and a Webra 50 on an Extreme Flight Edge. Comparing these two setups, the burrito responds much, much quicker to throttle changes. I am not talking about spool time, I talking airplane response time. I can punch the throttle on my Webra and hear it rev up while it gradually climbs out. I don't really hear the YS rev, the plane just jumps when I hit the throttle. I had an "accident" a while back with the Webra/Edge. I doubt it would have happened with the YS/Burrito. The Burrito would have been up and away before any contact was made.
On the other hand, you can't beat the economy of the 2 stroker, both initial puchase and fuel costs! I'm sure I'll always have both on my profiles.
Matt
Old 11-15-2004, 01:12 AM
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Default RE: 2 stroke for 3d?

Too bad that the YS is the only 4 stroke that has that kind of transition and power. I personally switched from 4 strokes over to 2 strokes in my profiles/3D type planes and have not regretted it. If you can afford the YS and do not mind having to send them into the shop for service/paying for at least 20% nitro fuel, then by all means buy the YS. For me the 2 strokes are just a little easier to deal with.

BTW, how many Webra 50s do you see for sell on ebay? Not too many compared to some brands of 4 strokes. Things that make you go hmmmm.
Old 11-15-2004, 01:00 PM
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Default RE: 2 stroke for 3d?

I answered last year's R/C report's survey regarding "the best R/C purchase I made in the past 12 months" this way:

Saito .72

On a 4.5 lb profile with a Zinger 14x4 or Master Airscrew 13x6 Scimitar, the instant thrust is amazing. I bought it for the sound (or less of it, when practiceing TR's) but it immedately made me look like a much better pilot. As basmntdweller says, the plane will move quicker when you gun a 4 stroke than a 2 stroke will. I had an OS .46 with a tower muffler, and the Saito lets me get away with murder compared to the 2 stroke.

A friend has the YS 63, and it too is a strong runner. I don't mean to start a YS vs Saito sidetrack here, but he had much more trouble setting up his YS than me with my Saito. Part of his trouble I think is his YS won't swing the props my Saito will, as it seems to like less pitch and turns higher RPM. He likes the MA 13x5 K series prop best. A Zinger 14x4 is definitely too much for his motor. I must say that his YS .63 is a stronger motor than my .72, but I notice it's on par with another friend's Saito .82 (also swinging a Zinger 14x4). All three planes are identical models, and within a few ounces of each other)

Bigger props, glo plugs last forever, ear friendly sound, smaller lighter mufflers, amazing power for the weight and better looking (IMO). Up till now, I thought cost was the ONLY discriminator.

Interesting that jon595 likes the Webra 50 better. I'm sure the Webra is a stronger motor than the OS .46. I've not heard too many other opinions matching Jon's however. Jon, what moves do you feel the Webra 50 does better than a Saito .72 (or .82)? I think you're the only pilot I've ever met seen or heard who actually has tried both and prefers the 2 stroke for performance reasons. My saito has been trouble free for over a year now. I checked the valves once, but that was really the only maintenance I do except keeping it clean and after run oil.
Old 11-15-2004, 01:27 PM
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Default RE: 2 stroke for 3d?

Actually - something can be said for both the 4 stroke and 2-stroke engines when flying 3D. When I first started flying 3D all I had was 2 stroke engines - OS .46FX, OS .50SX and a Magnum XLS 52A. Each of these are (as far as I'm concerned) pretty much tops in their class as far as power, performance and maintenance for the 2 stroke lineup. Each give me the low end and top end performance for the kind of flying that I like to do - anything 3D. The prop of my choice is the APC 12.25"x3.75" - it goes on everything I own (in this engine size range).

Recently, after drooling about them for sooooo long, I finally broke down and purchased a Saito .72 4 stroke for one of my new profile designs. I have a little under 2 gal. of fuel ran through it so far and for all practical purposes it isn't even broke in yet. But I will say this about the 4 stroke versus the 2 stroke:
a.) Gotta love that 4 stroke sound!!! It is a more "full scale" sound than the "whine" of the 2 strokes.
b.) The 4 stroke definitely has greater low end torque over the 2 stroke.
c.) The 4 stroke seems to get a little better fuel economy but the YS 20-20 blend that I use is a bit more expensive than the 15% I use in my 2 strokes. This is not a big deal though.
d.) It really peeves some folks off that I have such an expensive engine on a "profile" - and I like that! Yes I know....I'm sick......
e.) The big honkin' engine really looks sweet mounted on the nose of my profile.

The 2 strokes will give you:
a.) A greater high end performance
b.) Lower initial cost and cheaper to replace in case of an accident
c.) Lower weight than 4 strokes (depending on size comparisons)
d.) Less expensive fuel costs (especially if using 10%)

I suppose there are other factors that one can consider but these are a few that come to mind immediately for me. If I had to say which one I like best on my planes I would really honestly have to go with the 2 strokes.....just my personal preference..... Good things can be said for both type engines and I imagine everyone has their own likes and dislikes. I actuallyl like both but for all new purchases - it will most likely be the 2 stroke variety.
Old 11-15-2004, 02:10 PM
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Default RE: 2 stroke for 3d?

The suitability of a 2-stroke for profile use has a great deal to do with its performance range and design.

Jett offers two excellent 3D engines in the "40" size class. The SJ-61H and the BSE-76L. Both are designed from the start for use with bigger props, lower rpm, superiour midrange torque, positive fuel draw and linear throttle response. Either engine weights about the same as an OS46FX. No special fuel.... normal 10-15% sport fuel.

So basically you get similar performance to a 4 stroke, but the smoothness and compact footprint of a 2 stroke.

61H typically turn 12.25x3.25, 12x4 and 13x4 props.


The .76L is set up to run great with 13x6, 14x4W, 14x6 (shown below). The BSE-120 is the "60 size" version of the 3D engines.

I trust this is helpful.
Bob
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Old 11-30-2004, 07:00 PM
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Default RE: 2 stroke for 3d?

I have been flying 2 strokes on my 3D profiles and have not tried any four strokes yet. However, I have compared the Irvine .53 to the Jett .76L that Bob mentioned above. I can say that the difference is in the prop... The Jett can spool up a 14x4 without any problem. The Irvine .53 and other similar .46 to .50 2 Strokes typically spin a 12x4 at higher RPM. They get the job done just fine, but the vertical is noticeably sluggish compared to the Jett .76L. To me, 36% more disk area (with no weight penalty) is a real advantage for 3D.

TX

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