Im flying on 15% byron fuel, sig extra 300 xs (14lbs ), with a saito 180.

I fly primarily with a apc 16/8. spins about 9600 rpm. Flies nicely, good but not unlimited vertical.

Would a 17/6 be better? I have flown a 14/6 on my saito 90, and it seemed like the plane flew in slow motion! Nice verticle, but dont try to do large loops

Anyone try a 17/8 or a 16/10 on 15% fuel ???? I always though that with a 4 stroke, you wanted the rpm around 8500-9000, but no one seems to fly in this range. Shouldnt we be using larger props???

Zinger pro 18/6 on the 180 with 10-15% fuel works great. You get a good bit more vertical. I can't say how it would work on the Extra. A fellow 3D flier at my club uses the same props with the OS 160 on the Sig Cap 231 and a Lanier Edge.

I ran the thrust and rpm numbers through a thrust program

16/8 = 9400 rpm. 16 lbs thrust, 75 mph
18/6=8400 rpm 24 lbs thrust 48 mph

A top speed of 48 mph is rather slow, isnt it? Sounds less than 2X stall speed...do a lot of you fly an 18/6???

50mph isn't really that slow. If you think of sitting on the side of a highway with cars doing 55 mph right in front of you they seem like they are hauling. Most 3D and Funfly type planes don't want an extreme variation in speed they just want to go at a moderate speed with extreme amounts of thrust. Watch someone with a funfly plane with a 3 or 4 pitch fly around they move almost the same speed no matter if they are at half or full throttle. The thrust program is just a general guide, in practice you'll find the 18x6 just fine.

I don't know what program you're running. My 180 turns the 18/6 at 10500 RPM peaked on 10% fuel on the bench. I don't let it run that lean on a plane.

But even so, 50mph is plenty for a 3D plane. Speed ain't gonna help much.


(edited by brad below)

Whoa... I just checked the HP on that load. I may be mis-remembering the RPM's on that prop/engine combo. That's over 4hp. I'll recheck...

Anywhoo... 50mph is enough.

Check your tach. 10500 on a 180 with 10%. I think something is wrong here. Maybe with a 14 inch prop.

yea, see my edit above :stupid:

thank you for all of the replies. Ill try the 16/10 next. If Im not happy then the 18/6 will be next.

Anyone know at what rpm the 180 reaches peak torque???

bpu699,

You seemed to want more vertical. 16x10 isn't going to improve that over a 16x8. It'll get worse. You'll get less thrust and more top speed.

Which problem are you trying to solve? Thrust for vertical? Or do you want more speed?

bpu699

Don't even bother going with the 16x10 it will only make your condition worse. Granted you will be able to build more speed but you will loose it quicker on the uplines. Using the 16x10 would be like putting your car in 5th gear to climb a hill, it just doesn't make sense. If your looking for true unlimited vertical your best bet is going with the largest diameter prop (18") and shallowest pitch (6") you can obtain while still keeping the plane happy at level flight and the motor in it's powerband (~9,000rpm). One variable that will make a difference is the brand of prop. Blade width and contour affect thrust as well, I think most people would recommend either a Zinger Pro 18-6 or APC 18-6w.

Quickie is right.

Also, the APC weighs more. If you need some more nose weight, use that one. If you need less nose weight, consider the zinger pro.

I'm using an APC 17x6 on my Saito 180 with great results. In the past, I've used 16x8 APCs with decent results. Note: The Zinger wood 18x5 or 6 have a significantly larger diameter at the center of the prop (almost a 1/2 inch wider than the APC). I mention this because you'll need to accomodate this monster prop in a nose cone (I presume).

-Juhan

Perhaps Im looking for too much!

I dont need my planes to fly VERY quickly, but I do expect them to knike edge and do decent size loops, with the ability to 3d.

With the 16/8 I can barely knife edge with full rudder deflection on the 300xs, verticle is good but not unlimited. I guess Im wondering if the 16/8 is enough of a "load" for this motor?

Im sure I can get stellar vertical with a 17/6 (20+ pounds calculated thrust) , but Im sure my ability to knife edge will further deteriorate, and forget about lar ge loops...Perhaps Im asking too much of a saito 180?

How about more rudder area?

You're right. 14 lbs is kinda on the heavy side for the 180 and 3D. But, last time I checked, knife-edge ain't 3D. The wings aren't lifting, but they're not stalled, either.

Use a Mejzlik 18X6 and you will not be dissapointed. The prop is expensive but well worth it. I fly my Sig extra with a OS 160 and
a 18X6. Verticle is excellent!

I had this plane combo 'till this spring but here's what my experiences were.

I first used a cleveland cyclonic (mezjlik knock off) 16x8 prop. It flew ok, but needed more vertical, so I made a call to desert aircraft and they suggested an 18x6 mezjlik. I thought that it would be too much, but ordered it anyway. HUGE difference. Didn't lose any apparent top speed, but vertical was much better and the engine liked the prop better. I only lost about 400 rpm with this prop over the 16x8 as well.

Unfortunately I lost this plane on the first flight this year. Radio issues. I'm in the process of ordering another one with an FPE 2.4.

-Aaron

I am always in search of "propeller nirvana" and have run a BUNCH of them on my big Saito 180 powered fun-fly . In APC props I have run 16x10, 18x8 and 17x6. The APC 17x6 is the best by far for my application (http://www.devino.org/mark/airplanepics/aeroworks.htm).

I started with a YS 120 on that plane, but Saito 180'ed it a month ago.

I have the 17/6 APC on my 180. It will tac 9760 on the ground. I am trying to get the APC 18/6 Wide from my LHS but its on back-order. I do have a Menz 18/6 on ordrer.

tony

Tonyc, that prop sounds about right, combine this with some 30% heli fuel and you'll be rockin.

I agree TonyC, the menz 18x6 sounds good. And like I said, I am ALWAYS in search of the best prop. Who did you order from and what did you pay?

-Cheech

Just an update. The 16/10 was no better than the 16/8 - either in top speed or verticle.

The 17/8, was awesome!!! Spun faster than the 16/10, flew faster, and damn near unlimited verticle on a 90 degree day!!! Wow, what an improvement. This engine really likes the biggerr props. I am now a happy camper!

I tried an 18x6 and think the 17x8 APC is the choice.
I have a 14lb. 3oz. Cermark Pitts with the 1.80 and get plenty of verticle, torque rolls and hover capabilities. Don't have much throttle to get out of trouble, but plenty good for 20 feet above the ground stuff. Give up on the bigger props.