When I read the MAN review of the Global Ultimate they said they got the plane to hover at 2/3 throttle using a Magnum 91 FS. I bought the same plane and put a Saito 91 in it thinking I would get even better performance. The plane flies really well and has plenty of power but it does not hover and definately does not have unlimited vertical. How is this possible? It is an ARF so I didn't build it too heavy, it does have 1oz of lead in the tail, but that seems reasonable.

The Satio is performing well, it is spinning a 14-6 prop at 9,500 RPM. Any input as to what I am missing here. There is no way the Magnum outperforms the Saito by that much, could the kit have gotten larger or heavier since the review?

What is the weight? That is a .46 size plane, a .91 Saito should pull that plane out of sight.

I figure that's about 9 pounds of static thrust. I can't imagine that plane weighs more than 6 pounds. What kind of 14x6 prop? Some props are better than others. A Saito should out perform a Magnum, all things being equal. It's a tad lighter too. Is the engine losing power in the air?

hey there,
I have the same setup you do. Here's a few facts for comparison.

I am flying the global ultimate ARF with Saito 91. I run the MA 14x6 wide chord prop. I use 20%nitro with 20%oil (all synth). I'm using the OS F plug. I am flying at less than 500ft elevation in 80% humidity and near 90degrees F. This engine peaks at 10,200. I run it a tad rich at 9600rpm. Its still very new but even at this rpm it climbs forever vertically. I weighed this thing too. Ready to fly weight with fuel in the tank was an astoundingly heavy 7.8lbs. I'm using a 4 cell NIMH pack and only 4 servos. Granted some are hi torq BB servos, but I did not add additional servos. I added 1.5 ounces to the tail for my liking. It will fly without any but, I like a more pitch sensitive model.

Things to consider.
What is your elevation and temp?....higher elevation will make difference

What fuel are you using?

If they are the same or better perhaps you simply have a poor performer out of the box..??

Incidently, I bought two Saito 91s a the same time. The other is installed in a Hobbico Extra 300 60size. It also came out to the same weight ready to fly. it has the same power to weight performance and runs the same RPMs.

I have 1997 model Saito 91S on a Stinger 60 I've been flying for years. Its a heavy 8.5 lbs and the engine is a little tired but turns a 14x6 9400rpm. It will hold this model at a hover but will not climb out. (again at 500ft and lower altitude).

Hope this helps...

hawk

This is really interesting.

I fly at sea level in southern CA so it is usually pretty warm, but nothing extreme. I am using Powermaster YS20/20 fuel and the plane weighs in at 6.5 lbs dry, so probably a tad over 7 wet.

The prop I have been using is a Topflight 14-6 wood with an OS F plug. The 9,500 rpms on the ground should be plenty of power, I could lean it out and try to get ten, but the engine still has only about an hour to an hour and a half on it.

There is the possibility that the plane is losing power in the air, but I don't know how to assess that. Any suggestions.

The plane should be out of sight.

You may want to consider a different prop. I kinda like the wood props also, but My O.S. .91 Surpass likes the Pro Zinger props better than the topflight.

Another idea would be to try a 15x6 at slightly less rpms.

I have a global ultimate with a Magnum 91FS, APC 14-6 Prop Smoke system 6 Mini HI TQ servos and a 5 Cell 6volt battery.
I have ran the engine for brake in but haven't flown it yet at 1/2 throttle the plane seems to hover in the vertical position and at full power looks like it will have great vertical acceleration. Thats at 2800 feet in the mojave desert.

JTolomeo have you flown this yet? how does it handle with all that in it?I also have this with a .91 f/s pumped with a smoke system but have yet to even fire the engine.

The Global Ultimate is not the lightest of planes. If you really want to prop hang then go for something else. I have one with an SC80 ... the plane is very very nice to fly but I would not prop hang her with any engine. You can but its not the best of planes to. Oh yes ... I fly with the muffler off ... sounds so darn scale! Hehehe ... I use the engine pressure nipple for the tank.

If you fly with the muffle off dont you loose that compression?

***Newb here***

Doesn't that feed used oil back into the tank ? Burnt nitro that has passed through the crank case , rings and valves ? Or does your engine have a pressure nipple mine does not ?