4-stroke vs. 2-stroke....?
 

which one should i get for my SIG Senior Trainer (80" wingspan) i'ma lookin' at the magnum .61 4-stroke or the .46o.s.

RE: 4-stroke vs. 2-stroke....?
 

4 stroke, hands down.

RE: 4-stroke vs. 2-stroke....?
 

I currently have a Magnum .91 on mine. Overpowered, but fun! This big plane really needs a 4-stroke to sound right on a fly-by. I vote for the .61!

RE: 4-stroke vs. 2-stroke....?
 

Go for the Magnum .61 4-stroke.

RE: 4-stroke vs. 2-stroke....?
 

I'll agree withthe 4s engine also. But if you do go with a two stroke get the XLS 46 Magnum engine.

Bill.

RE: 4-stroke vs. 2-stroke....?
 

IMO the extra power from an oversized engine is just not that fun on this plane. I had a .46 TT on mine to start and had to add a ridiculous amount of down thrust. Put an older K&B .40 on it and it powers it just fine except it could use more power on hot days. Thinking of putting a modern .40 on it or a .52 sized four stroke. The .61 may be OK, but a .70 would be too much. It flies fine overpowered with a lot of down thrust but you tend to fly half power except for the initial climb out. I would rather put the hotter engine on a fully aerobatic airplane. I can't say that using the four stroke would be any better.

But that is just my opinion, if overpowering a floater is fun to you, then by all means do so. There is one at our club with a .61 K&B at our club, but it is weighed down with a remote video system.

RE: 4-stroke vs. 2-stroke....?
 

I knows it a big plane while keeping itself light enough but I am a little sceptical, perhaps with a 46 for real easy flying. I think the Magnum 61 4C is a 'better' choice since you wanna have an easy flyer. You can hear it putter away ...

RE: 4-stroke vs. 2-stroke....?
 

Get the Magnum .61 four stroke, I love mine, plus they are on sale @hobbypeople*net for only 119.99 ($50 bucks off!!!). A Bargain!!

BTW If you get a two stroke, get the OS .46 AX, I have that also and love it, only requires a back flip of the spinner and it is purring like a kitten.

RE: 4-stroke vs. 2-stroke....?
 

A rule of thumb for engine power is to consider the weight, not the size. The Sig Senior weighs only about 6 pounds, so with a .40 and its large size it cliimbs well, but fly slowly. With more power it doesn't fly much faster, but climbs faster, doesnt' seem to do aerobatics any better. In fact it doesn't do anything outside of a inside loop well with or without a lot of power. A .46 will need a stack of about a dozen washers in the rear of the engine to prevent you from holding the stick down at full power.

RE: 4-stroke vs. 2-stroke....?
 

I have a Saito .65 on mine, seems like the engine is just right for this airplane.

RE: 4-stroke vs. 2-stroke....?
 

HI!
Don't be fooled to put on a too large engine on a high-winged trainer!! Low weight is the rule of thumb too good flight behavior.Not lot's of power!
A 7.5cc too 8.0cc two stroke is a good choice. The MVVS .49 is the engine of choice with a 12x4 APC prop.
Can't see why people fancy four strokes ...they don't sound like "real" airplanes at all..just put, put, put,......;)

Regards!
Jan K

RE: 4-stroke vs. 2-stroke....?
 

Ever listen to a YS four stroke? There is no put, put, put coming out of it, just awesome supercharger whine.

Listen:

* [link=http://www.whitetyphoon.com/rc/gsp_spit_show_pass.mpg]No Put Put Here[/link]

* [link=http://www.whitetyphoon.com/rc/h9_corsair/movies/HighSpeedPass02.mpg]No Put Put Here Either[/link]

* [link=http://www.whitetyphoon.com/rc/h9_corsair/movies/HighSpeedPass03.mpg]And Definitely No Put Put Here[/link]

RE: 4-stroke vs. 2-stroke....?
 

Richard L, This is what I get when analyzing your third video using matching generated tones:

Perceived rpm approaching: 14,100
Perceived rpm departing: 10,500

Now applying Christian Doppler's wisdom:

Actual revs at bottom of dive: about 12,000
Speed: 113 mph (181 km/h)

Good speed - what model, engine and prop is that?

RE: 4-stroke vs. 2-stroke....?
 

Holy smoke, I didn't think the plane was that fast.

Model: Hangar 9 F4U Corsair
Wingspan: 65.25"
Dry Weight: 10 lbs
Engine: YS 110FZ four stroke
Prop: Graupner 15x8 two blade
Fuel: Powermaster YS 20/20

RE: 4-stroke vs. 2-stroke....?
 

Yeah, it's funny - the pitch and revs suggest something around the 90mph mark but my estimates suggest more. There is an opportunity for inaccuracy when attempting to match tones with engine noise but it's usually not too far out. Also, the models can slow down significantly and reduce revs once the dive levels out which can skew the departure rev reading.

It might be 90mph, but watching the video, it sure seems pretty quick!

RE: 4-stroke vs. 2-stroke....?
 

Harry:

A 15x8 prop at 12K rpm, allowing only 10% slip, is flying at 82 mph minus a hair. The 8" pitch at 16K rpm is still not quite to 110 mph if we allow the same 10% slip.

Bill.

RE: 4-stroke vs. 2-stroke....?
 

The Sig Senior needs quite a bit of weight in front to balance. Mine, with the .91 balances perfectly. If you gotta add weight, I vote for weight that does something!

RE: 4-stroke vs. 2-stroke....?
 

Yep, I got a lot of weight in the nose of mine. But why put a .91 on it when a .40 does fine? The .91 is in a Fokker Triplane.

RE: 4-stroke vs. 2-stroke....?
 

....I'd put a Magnum .91 FS in it. The 80 inch plane will be a dog with the .61. :eek:

FBD. :D

RE: 4-stroke vs. 2-stroke....?
 

I don't think you have flown one. A .91 is enough power to fly straight up. But with positive wing incedence, down and right engine thrust; it is not a 3D plane. In fact if built light a .52 two stroke or .70 four stroke can take it straight up. It fly slow and is best for floating lazily around and doing touch and goes.

Also a great trainer! Slower than others which gives the newbie more time to react.

RE: 4-stroke vs. 2-stroke....?
 

Thre ain't no supercharger in a YS- but it is supercharged.
I reworked some supercharger equipped OS 1.2 engines - what a mess-
got em to perform reliably but that had to be the worst bit of piss poor design work I ever saw coming from OS.
Anyone who understands supercharger applications thoroughly, would ever do that.

RE: 4-stroke vs. 2-stroke....?
 

I meant to say "Super Dog" ! :eek:

Dave. :)

RE: 4-stroke vs. 2-stroke....?
 

THANKS FOR ALL THE REPLIES FOLKS. THIS IS THE BEST SITE ON THE NET I'VE FOUND IN THE 3 YEARS OF HAVING A COMPUTER.[sm=sunsmiley.gif]

RE: 4-stroke vs. 2-stroke....?
 

i like'um cause they sound so cool,and they look so darn good.

RE: 4-stroke vs. 2-stroke....?
 

That's exactly why people like them I haven't heard many real planes with engines that whine at 15k rpms.