4*40 engine size
 

Could use some opinions as to what is the very best engine to put on the front of a 4*40 for just Sunday afternoon fun flying. Don't necessarily need unlimited vertical and will not be trying to set any new speed records. Just want a docile, fun to fly airplane. Anyone with ideas and/or experience, please share.

Max

4*40 engine size
 

If you want your Four Star to be docile and and still be fun to fly try something like a OS 40LA, it will pull the 4-Star around fine for normal flight. I have had one with a 46FX and it was as aerobatic as anyother plane out there. You even can go with a strong 46 cause you dont have to fly around at full throttle, you could just cruise along and use the extra power if you ever get in trouble!

4*40 engine size
 

This plane will fly fine with a bushing .40

a 46FX will make it do almost anything you desire

4*40 engine size
 

I have a Thunder Tiger Pro .46 on mine with an 11x5 prop. Flies great, slow or fast, with plenty of pull.

Mike

4*40 engine size
 

I've had one with 40LA, 46LA, and 46FX.
The 46LA was probably the best match.

Larry

4*40 engine size
 

Have one with a Magnum 40XLS, simply a perfect combo. This plane will do everything in the book with the right control throws. I prefer the Manums to OS now because they are OS copies, run awesome, and are much less expensive.

4*40 power
 

Hey Guys:

Thank you all for your responses. The unanimous opinion here is either .40 or .46 power. My question was triggered because I am reading of them with some awesome size four strokers on them and I was just wondering how all that weight on the front was going to make it handle. I have a virtually new OS .46 SF with a slimline muffler on it that I want to put inside a FiberGlass Specialties cowl. How do you guys think that would work?

Max

4*40 engine size
 

The 46SF should be great for it. The 4*40 is a light plane; a light engine helps keep it that way.

Larry

4*40 engine size
 

I have a OS46fx on my 4 40 It is a great flying plane. Slows down great for landing but can do a knife edge around the field and has unlimited vertical if you want it. With a 11x5 prop it will fly slow or get a little wild if I want. Gary

4*40 engine size
 

I believe the awesome size four strokers you read about are on 4*60's not 40's. The 40 or 46 should be great!

4*40 engine size
 

Max,
While I concur that they (sport) fly great with just a LIGHT bushed .40-.46 engine, and are a BLAST with high performance dual BB .40-.50 engines, you also ask about four strokes. Now you are into a combination I love! I have an ancient 4*40 that is now on it's THIRD 4 stroke engine! It started life with a 1982 vintage Enya .60 four stroke. It flew it great, but the engine though reliable, was never my favorite 4 stroke. Next I fropped an early (high compression version) Saito .80 into the plane. Lots of power, but a bit tempermental. Finally, in about 1995-96 I put an O.S. .70 Surpass into it. Presto, a great combination. Great idle, unvelievable power, and perfect manners. I can now putt-putt around the sky if I want, or kick her in the butt and do amazing snaps, spins, tumbles, and a wicked flat spin at full throttle.
You ask about the extra weight. All I had to do was to mount the servos at the very back of the servo compartment (right in front of the trailing edge of the wing. The receiver goes just in front of the servos. Then, before covering, I used the receiver pack as the final balance weight, and in my plane, it goes about half-way between the trailing edge of the wing and the tail. Just make sue you use STRONG cross bracing added in the fuse at that point to secure the pack (don'r ask how I found this out!). This will balance the plane as per specs without having to ad extra weight. The only other thing you have to watch is prop clearance. With the 11 and 12 inch props, these size four strokes will swing, ground clearance is VERY limited with the stock gear.
If you don't want/need the Saturn Five vertical performance, but still want to try a 4 stroke, I have also seen them fly VERY well with the .50-.60 sized four strokes like the Enya, Saito, YS and OS engines. These being lighter also may allow you to put the battery pack in a more conventional location to achieve balance.

Two stroke, or Four stroke, either way, I think you will enjoy your 4 Star .40! Mine has been flown off land and snow and also in the dark (chemical lights) in club night fliys, and it remains an old favorite.

Lee

4*40 power
 

Lee:

Really appreciate your input here. Even with the CG correct, won't the added weight up front mean hotter landings with the OS .70 Surpass than with a lighter engine? I have three engines available for this application: the OS .46SF mentioned earlier in this thread, an old but never run HP .40 that is allegedly an absolute screamer, and an OS .70 Surpass that is obviously your favorite. I guess another concern is fitting whatever engine I use inside a cowl. Steve at Fiberglass Specialties says he is going to produce a cowl for the 4* soon, and I will want to make the front look as good as the rest of the plane. That may be the deciding factor, but I guess I really need to have the cowl in hand to make that decision. Any thoughts? Be safe

Max

Hotter Landings?
 

Max,
I see what you mean about the slight increase in weight increasing landing speed. Technically, I am sure you are correct that it does increase the landing speed somewhat. However, faster is a relative term. With that said, remember that the 4* planes as a line tend to have very low wing loadings (I even cluipped the wing on my 4*60 to improve roll rate, and it STILL lands slow!). One beef you may often hear, especially about the .40 sized 4* is that they tend to "float" on landing. They get down into ground effect and even as they slow way down, they tend to float and float, and... you get the idea. In other words, they will slow WAY down, due to their low wing loading. So even though I am sure the slightly heavier engine does increase the landing speed somewhat, I hardly notice. It STILL is a easy plane to float in. In fact, one advantage I see of the four stroke .70 is that with the big wide blade prop it swings, it isn't as bad at floating on landing. Once you go to idle, the big prop gives more braking effect and it slows down real nice to land.
You also ask about fitting the engine inside a cowl. I guess I really can't say much with confidence here since the stock plane doesn't use a cowl as such. If you do use the Surpass .70, I do know that even with the engine set as far back in the engine compartment as it will go, the prop driver is still a little farther forward of the front of the fuselage side "cheeks" than I would like (It isn't flush", but it sure isn't noticable unless you are right up on the plane (I don't use a spinner on mine as it would just add more weight forward of the CG and also make the long engine shaft more noticeable). If you decide to cowl the front of the plane, I am sure you could adjust the position of a cowl slightly to make up for the slight increase in engine length, should you decide to go with the bigger four strokes.

Have fun,
Lee

4*40
 

Lee:
You make some really good points in your note. I have actually seen airplanes that wouldn't land due to ground effect. Also makes sense that the prop being so wide will cause a braking effect with the engine at idle.
As to the cowl problem, I don't know how the cowl fits yet. Don't even know if the cheeks are left intact or if they are removed at the firewall. And whether or not the cowl can be adjusted as far as fore and aft positioning is concerned. Need to have the cowl in hand to address those problems, so this is all conjecture at this point. Really interesting to think about all these things tho. I really do like 4 strokes for several reasons including the raw torque they produce and the sound of them in flight. They just sound so much more like the real thing than the 2 strokes do.
You say you are not using a spinner on your engine. Are you hand starting this monster? And if so, how many fingers have you lost to this point? I just cleaned a well used Magnum .91 four stroke in hot anti freeze, then put it on a test stand and started it to see if it would still run. Was my first attempt at the anti freeze cleaning method and I wasn't sure the engine would run again. Anyway, after it spit all the anti freeze solution out of its various orifices, it coughed a couple times and then started. I then killed it and turned it through a couple of times by hand with the glo plug lit and it scared the prunes out of me. Had the impression if that monster popped back it would have removed my hand somewhere around the elbow. So I put a spinner on it and used an electric starter(chicken that I am) and it started immediately, idled down beautifully, transitioned very well, and ran good on top end, so I guess the anti freeze trick works. Sure cleaned up an engine that looked like the wrath of God before cleaning.
Gotta run. Am building a Sog Hog Bipe for a lady in Ohio that I need to work on. We are putting a NIB Thunder Tiger .91 four stroker on this puppy that needs to be broken in. It is almost 60 degrees outside today. May be a good time to start this big boy and see what I can do with it. Keep in touch. Be Safe------Max

Engine starting
 

Max,
Have fun breaking in that new .91 FS. I always enjoy breaking in a new engine....when ever I can find the time any more!
Anyway, you ask how I start the Surpass .70 without a spinner. Actually, it isn't hard, and NO I don't flip it with my finger (though I am sure it would fire right up)! I have enough scars on my fingers from unintended prop/flesh encounters over the years already! All I do is turn the rubber insert in my starter cup around and slide the small hole in the rubber center of the cup over the prop shaft/spinner nut. It grabs hold just fine and spins the engine right over. I actually do the same thing on my 4*60, and speaking of beasts, I run a YS .91 AC (double nutted) on it with 25-30% Nitro!

Later,
Lee

4*40 engine size
 

I put a Saito .56 in mine. Its the same size as the older .50 version (shown in the plans). Pleanty of power, no problems. Flies great at about half throttle. Balance was right-on.

4*40 engine size
 

I have a os46fx on my 4* 40 and changed from a master air screw 11 6 to a apc 11 4 prop this weekend and wow 15 to 20 yards down the runway and can pull straight up and do a roll and has unlimited vertical yet slows down for a very nice easy landing. It will also do some 3D and knife edges.Just that change in props made a good flying plane into a great one. I only used the battery placement to get the CG at the balance point. The OS46FX and the 4/40 is a great combo for a 2nd plane it will take and land slow and will fly great but can get a little wild when your ready. Gary