Hi, I'm new to the forum and a relative beginner to R/C Airplanes but have a question. I am in the process of building the Global ARF Decathlon 52..Specs as follows:

Wing Span 63"
Wing Area 641 sq inches
Wing loading 20-22 oz per sq ft
Length 45.5 "
Weight RTF 5.75-6.25 lbs

The manual recommends engines of .52-.61 2-stroke or .70-.91 4-stroke. I prefer going with a 4-stroke. In the past I have used exclusively OS FX engines....61 on my Hobbistar Trainer and .46 on my Falcon Ready float plane. I was thinking of the Saito .72 4-stroke for this one but think it might be overkill for this size plane. Any feedback and recommendations on engine and prop size would be appreciated!!!!!!!!!! Thanks in advance.

from the specs you provided the 72 will work fine.


good luck

Thanks DiabloKid!!! That seems to be the concensus from my fellow club members too. Any preference between the Saito .72 and the OS .70 Surpass? People are telling me that the Saito might be a better engine, but requires constant/frequent "tweaking". I like to fly not tweak. Looking for opinions.

Im on my 2nd Saito and have never really had to play with the needles at all. I have a 91 and a 100. Im looking for a 72 as well right now. Simply the best bang for the buck you can get.

By the way, welcome to the forums


good luck

Hey Frog...

I have been flying Saito's for years... What "Constant Tweaking" are you refering to?

Have you seen me tweak my Saito 180? Tune it first flight of the day to adjust for conditions and fly. Once the engines are set up, they run great.

Go for the Saito 72 or even 91 based on what the manual calls for... If you want a more scale plane, use the 72.

I have several Saito's and sure don't understand this tweaking all the time stuff.
After they are broken in I seldom touch them. Latly with the temperature dropping
from the 100's to the 50's they require a tweak but that is about it.
So how do you like that ARF. I have been eyeballing it for a Saito .72 I have
sitting around. Looks nice but I have no experiance with Global ARF'a

Thanks for the info.

IronCross...I'm still in the assembly stages but so far it is going together real nice. This is only my 4th plane so I still use instructions quite a bit, but so far so good. Only reall challenge I had was when I cut out the back end of the fuse to insert the horizontal stab and elevator, you're supposed to replace the cut out piece back into the opening. Problem was that the rudder hunge was cut right in that spot so when I cut the wood, the small piece fell apart. I had to make/cut a new piece, glue it, cover it and re-slot it for the hinge. No big deal, but all this was new for me but turned out great.

This ARF came pretty highly recommended by our Club Pres. who has flown this first hand..he loves it. He has also seen people put in .46 size 2-strokes in this and fly just fine. After using 2-strokes and hearing and seeing 4-strokes, there was no going back!

Glad to hear that about the plane.
Your right about those four strokes. You can
get used to them real fast.
Let us know how it flys for you will you.
Thanks
Roger

Will do.....might not be until Spring though...getting a little chilly here these days.

Oh Oh, I didn't see the location before. How the heck do you wait till spring. I would
have to be retrained :-}
Guess I will let you know how mine turns out. Not unusual for us to be flying around Xmas
in our T-shirts

Ok stop rubbing it in. Some of the brave hearts do put skis on their planes. I prefer to keep the feeling in my fingers and toes. Best I can do is to put the glow fuel to the side and pull out the small electric park fliers (yawn) and go fly indoors either at a high school field house or we rent out a golf dome after hours and fly there. Either way, my wife says it keeps me out of trouble. Little does she know...lol.

As for the Decathlon, I decided to go with the OS instead of the Saito. I know I give up a little on weight, but when I compare the rpm's and recommended props it looks like the OS puts out close to the same power with a smaller prop (smallest prop for Saito is 12x8 and OS was 11x8). Because our field has a grass runway, I not only have to look at ground clearance but GRASS clearance. I could increase the size of the wheels, but there is not too much more room in the wheel pants for that. Plus I think it would look stupid.

Now if you were a REAL nice guy, you would fly me out there and we could test fly these planes and compare notes...lol. But I can't make it over Christmas...have a scuba dive planned in the Carribean...sorry.

Now that's a thought.
Are you saying a 12" prop is pushing the ground clearance ?.
That's not good.
Specs call for a .91 fs and that is what I was planning on using.
That however I usually use 14" prop on. I fly off asphalt but it sounds
like 14" is not going to clear....

When you level off the fuse, the 14" will not clear. the 12" was cutting it very close (on grass at least...pretty good chanceit will work on asphalt). But the .91 does not fit on the engine mount either. You would either have to get a new nount or modify the stock mount. Besides, it's a 6 lb plane. I think a .91 would turn it into something just short of a missle. And if the wings don't hold up, you will have a missle. Those aren't fun, I've had that happen before.

Sounds like I had better scratch the .91 plan. I have a Saito .72 I
can use. Might have to go that route. I wonder what kind of .91 they were
thinking of

The packaging is really pushing the Magnum. I'm not familiar with it but maybe it has a smaller footprint.

No, definitly not smaller and also heavier. The heavier is the reason I wanted
to use it. Just guessing from the picture the nose looks a little short for the tail.
This means adding lead or a heavier/bigger engine to the nose. I could use the weight
to my advantage and Mag .91 has been an excellent running engine. I had it in a 40 size
Extra 300 and was that ever a nice setup. A sudden gust of gravity got it though.

A .91 in a 40 size....that had to be a screamer.

"Gust of Gravity"........gotta remember that one...lol.