TH suggests .4-.46 for the 4*. At the club, I was told to get a OS .55

I am worried that the 55 is a little too big?

The 4*40 would fly well with a 55 as long as it isn't to much heaver than the 40. They are a very flexable plane series.

Don

You can use the 55, however you will need to learn throttle managment. A good 46 would be perfect and save you some money as well. Good Luck, Dave

OS 46AX is a great engine. lots of power. the 55Ax is also a great engine. I think I would go with the 46. the plane was designed for a forty and the engines made now are putting out more power than the engines did when the 4* was first produced

"They are a very flexable plane series. "

So true. Mine started with a Magnum 52 4 stroke. I thought it was a rocket compared to my Senior. My limited tuning skills at that time could not get a reliable idle from it.
Next up was ST51- with a 11x5 APC, great combo, mucho power.
Next Saito 45- great engine, plane much more docile. Flys nice and on the wing, limited verticle.
Next TT46PRO- Not as much power as the ST51, more than the Saito 45. Good combo.
Next Saito 82- Incredible!! Use the throttle!
Next Saito 45- Breaking in another. Like this one probably the most. Again, real limited vertical but flies so nice.
Next OS55AX- Just got this, not mounted yet. I've heard so many good things about this one, had to find out myself.

The 4* flies so easy and predictable it has become my engine test/ break-in plane.


The 55 may be a little more flexible in the future compared to a 40 or 46, especially if the plane is on the heavy side.

Have fun, MikeB

On my Dolphin, which is a copy of the Four Star, I have a 46AX. I own a 55AX but think that that much engine on the plane is unnecessary (and apparently I like to overpower my planes). The plane rips with an 11x5, has tons of pull with a 12x5, and you could do even more with different props.

I suggest an OS 46AX.

55 for a 4* 40????

I run mine on a 46AX. I can take off in less than 10ft and go straight vertical after take off. 55AX is WAY WAY WAY WAY over kill for the 4* 40. I run 11x6 prop and it's FAST!

Save some money and get the 46ax and if you want to save more, look into a thunder tiger 46 pro.

Here I am with like the 2nd day with the plane. http://www.youtube.com/watch?v=VpXWc0pAayI

n19ht: Covering question...Does the 4* come with those white bands on the bottom of the wing or did you add those?


WMB: Let me know how the OS55AX works out as that is what I was told to use...what prop will you run on it?

I checked the weight and it has less weight than the Tower Trainer which I currently have and that runs on a TH46ABC and it can almost hover...

I run an Evolution .46 on my "Four Star 40". The plane came in at a total weight of only 5.5 LBS, and with those thin wings it moves along very well. Most of the time I'm just at 3/4 throttle. I have no problem with vertical either. The engine is very dependable and strong. Also, on my Sig "Something Extra" I have a Magnum XLS.46. This is an awsome engine! I think they're running for somewhere near $69. I don't have anything against the OS line. I have had three OS engines. They are good. I just think there are more economical and just as sound choices from some of the other manufacturers.

Good luck!
Frank

Thanks Sky. If I get a 46, I might just get a TH 46 as that seems to run fine for me on the trainer.
I am also a little worried about what else can run a 55...seems most 40 size want .4-.46 and most 60 size are .61+...Is 55 lost in the middle?

HI Chemie,

The plane was an ARF in Red. It came in 100% red. I mean EVERY corner of it was just plain red. They give you sheel of decals (the long starts that you see on top and side) the problem with this is the decals are a light white see through and are for show on the ground only. In the air can't see them. I flew the first day with just the stars on the top and the side and I had such a hard time with it because I could not figure out if the plane was up, down, left right. I Safely landed and went home. Bought a roll of white ultracote and made the strips and stars under the wing. It's helped a lot with the visibility. I HIGHLY advice that you add some pattern to the bottom (stripes, Checkers, of whatever that fancies you).

46 size engine is perfect for this plane.

As far as uses for 55ax, they exist, there are planes that can benefit from the extra power, 4* just isn't one of them. People that do kit builds will add different things in their planes which may make it heavier and they would have the option of using 55ax. Other scaled 40 size planes could also benefit from a 55ax such as the decathlon.

I perfer a .50 size engines becuase you'll never what model you might want to get later.
This way i don't have to worry about arf that are bricks, and if I wanted to install retract or floats, being under power won't be a problem.

The 4* .40 is .32-40 range originally. A .46 will pull it striaght up if you wanted to.

I'd be very careful if installing a .50 becuase the way the wing is designed or constructed. I'm not sure exactly how a 4* arf are consrtructed.
Even with a kit, I still build a little different.

The shear web are installed between the top and bottom spar....not a problem if you build it correctly or make sure there's no gaps.
I opt to put extra shear web by install it in front or back of the spar.

If you had ever had a wing rip away before..It's mostly from the wing joint seperating from one of the spar and ripping through
the opposite spar, from not enough epoxy or the epoxy didn't have enough hardener in it...Therefore cuasing the seperation.

There's so much force apply to the wing , it'll either try to compress it or rip the spars apart.

That's why the Fokker DRI Tri plane was call De flying coffin.lol It didn't have any main spars.

Thanks N19ht. I started a thread in the Tips section on the coverings as I was worried about exactly what you say. Solid color (red or yellow) on the wings.

I was thinking about getting the yellow and re-covering the bottom in red but when I saw yours, I thought that red with the white strips is a good solution.

One of our club members has a 55AX on his 4*40 but is planning to swap in a 46AX. He does all sorts of aerobatics and thinks the 55 is much more than the plane needs.

I have a 4*60 in yellow. It hasn't flown yet but I'm sure the decals will disappear as soon as it gets airborne. I put black stripes on the bottom of each wing in every other rib bay. I used monokote stuck down with windex, then went around the edges with a q-tip dipped in acetone. I've read that sealing the edges with acetone will keep the stripes from peeling off.

Fly on the wings, not the prop, the plane was never designed to be a racer. Throw a .40 or .46 on it, have a nice day.
Save the .55 for a heavier or faster 'wing' designed plane. OS prices are insane regardless, throw a Thunder Tiger .40 on it.

I have a Thunder Tiger 46 pro on mine and it is perfect. I love the TT pro. Good price and very reliable!

Sorry guys but I just don't see the big difference between the .46 and the .55 other then the torque. The .46 is hot but I don't see the .55 as any fire breather. I have been using the .55s in 40 size trainers now so my students have A bigger more useful engine in the future.
If you are going to spend the money on an OS .46 you may as well spend A few more bucks and get the .55.
Covering, I'm teaching my youngest student how to build and cover right now, the first build is the 4*60 with A Saito GK 100 for the engine. He is an outstanding pilot so this engine plane combo isn't over kill for him.
Problem is I took him to A local IMAC contest and he fell in love with A YAK that used floresent green, black and white for colors. It has flames and checkers all over the wing and fuse. I thought it was butt ugly but that plane stood out in the air like A sore thumb. We just really got going on the covering yesterday. I made the mistake of fooling around with one of my canopies for 60 size Extras and they fit, lost one of those to the 4* god too.
I will post up when this one is finished next week. So far this is what we have done.

chemie, The 55 got 4 oz run through it tonight. Has a light pinch at the top and used a heat gun to loosen it up before starting. Had the main way too rich. Got it leaned out to slightly rich of peak. Fuel had a bit of caster added. APC 11x5 on 10% hitting 12400 rpm slightly rich.

Idle was good. I don't like to let a new ABC idle too much, other wise the pinch will come back as the engine cools and grab the piston causing it to stop.

I pulled the Saito 45 and mount. Will get the engine mounted up tomorrow and hopefully give you a flight report on Wednesday. This combo weighs about 3 oz more which should put the plane a hair under 5 lbs. This will be mounted inverted.

As far as too much power for this plane- if it doesn't come with a weight penalty and fly heavy, the more the better. The ST51 rocked the 4* and I am expecting that and maybe a bit more. I already suspect that after it gets broken in, My other Saito 45 will get the job to get it dialed in. The 4* flies so nice on the wing. I hope to have a twin with the Saito's in the air next year.

Gray Beard, I already like the looks of the "sore thumb". Do give a few shots when complete.

So, to summarize, 46 versus 55, half the folks say "no way...way over kill" and half say "good idea"...never knew the question would get such different opinions.

Regarding Greybeard's comments, the OS55 is only $30 more than the OS46 and essentially the same weight (+1 oz) so I tend to agree if I go with OS.

If I go for .46, how would you compare Towerhobbies 46 to ThunderTiger Pro .46? (at the risk of an equally split debate as they are the same price).

Seems it is becoming more a "lower cost engine" versus "top of the line" question versus SIZE...do I go for less than $100 engine (and hence 46) or >$100 in which case OS55 wins? Am I thinking about this right?

Of course, you could say the same thing about the plane...4* versus Dolphin to save $50.

What prop for the 55? 46 seems 11x6 is suggested but I have read many people using 11x6 on the 55 too. With the same prop, what would the difference really be? Just torque? RPM higher on the 55?

You can tell I am not sure where to spend the money and whether I "future" proof the engine or go quality on plane which might get crunched.

(Maybe I'll move the TH 46 over from the trainer and try that out to start...)

Between the Tower and the Pro, the Pro is better. I also like the SK line of engines sold through Kangke even more. My number one pick for the under A hundred engines.

The TT Pro .46 is every bit as good of an engine as the O.S. Max .46 AX. Both are very user friendly, reliable, and easy to tune. The Thunder Tiger comes with a 3-year warranty instead of the O.S. Max's 2-year warranty, and will probably prove more durable in the long run. The O.S. Max .46 AX should have spare parts available from any hobby store on Earth, however, and in North America, the quality of service from Hobby Services (warranty provider for O.S. Max) is second to no one.

There are some very good engines available that would allow you to save money and provide "extra oompf" in the future if necessary. Ed Mooreman tested the JBA .56 available from Kangke USA for $79.99 and found that it was almost identical to the O.S. Max .55 AX in terms of power, weight, and usability. You can purchase the JBA .56 from http://www.kangkeusa.com or check them out at http://www.bj-model-engines.com/home.html A JBA engine isn't as nicely finished as an O.S. Max, nor is the warranty as good, but it's a hell of a good engine for the price.

You can read the whole thread here: http://www.rcuniverse.com/forum/m_67...tm.htm#6762745

The highlights include the following:

"Your engine has 5 break-in runs, plus 2 or 3 tanks for the rpm testing and 4 or 5 flights, I forget. It 1-flip started and never missed a beat in the air. I flew it with an APC 12.25-3.75 3D prop, Omega 10% castor blend fuel. I would say an 11-7 or 12-6 would be good props, too. The glow plug is a K&B that I had and nothing special. It didn’t come with one and this one lasted the whole time. I wouldn’t change any of the settings for the first flight. Oh, yes, I had a kill button set up on my JR 9303 and the engine shuts down after maybe a 1-3 second delay.

They both started by hand in usually 1 flip. The only time I used a starter was when I was doing the rpm runs and ran short runs to tune for max rpm, then shot down and changed props. The engine never got a chance to really cool down. I bumped it with a starter and it went right off.

To tell you the truth, I have looked for a down side and haven't found one. It just starts up, runs good and keeps on running. And it will definitely out turn any .46 out there. Maybe not a Jett on a small 10-6 prop, but probably would on a big one."

Several folks have been checking out the Aviatech .46 and Aviatech .53 2-strokes since they went on sale at http://www.sigmfg.com earlier this summer. You can try the .46 for $49.99 or move up to the .53 2-stroke for just $69.99. By most accounts, they require a little more work to break in and tune, but the folks who've purchased them have liked them.

There are lots of good choices on the market. I don't know anybody who has bought any of the O.S. Max AX-series engines and not been happy with them. It's really just a matter of budget and whether you want to try something different or stick with what you know.

Now this is really turning into "which engine maker is best" instead of just size.

Certainly, you have opened my eyes to beyond Tower Hobby. I see the SK.50 at $60 and the JBL .56 for $79 both seem much better priced than TT Pro .46 for $95 at TH. Neither has a "remote" (or rear) needle adjustment which my fingers appreciate and is on the TH, TT, and OS versions.

Maybe SK.5 is good middle ground on size and is certainly a low-cost option...not that I am pushing for lowest price....I would be willing to pay the $150 if OS brought something to the table...but the "2 for one" is hard to beat too.

I have the four star .40 w/ the 46ax and that thing hauls ass. I dont think you need a 55ax since the plane is pretty light. Also with the bigger engine you may run into balancing problems but Im not quite sure how much heavier the 55ax is.

I am building a Sig 4* and I bought an Aviastar 46 engine to put in it when I finish building. Aviastar is sold by sig. Take a look at them, the price is right and they seem to be good engines.

www.sigmfg.com

Well, if bought from SIG as a combo, the Aviastar 46 wins the prize for "cheapest" at $45....

SK.50 might still be the way I am leaning right now....it between 46 and 55 in size with the right price.