paully_321

Good morning,

I finished my Tiger 60 arf this weekend and I am looking to do a first flight soon. Here is my question though...On more than a few recommendations, I decided to put a OS 75 in it. Now I am wondering what prop I should use. The plane has tricycle gear and I am a bit worried about prop strikes if I use a 14 or 15.

Anyway, what should I go with?

Thanks,

Paul

goirish

I think the recommended starting prop is a 12/6 to 13/6. I was going to send you a chart but I can't get it to copy. It is called props, balancing, engine/prop ratio. Put this on google and it will pull it up for you. Type it as I have sent it. props, balancing, engine/prop ratio

Good luck

I have the tiger 60 with a ASP-75 and I run a 13/6 "floats like a butterfly, stings like a bee"

paully_321

Cool, the engine has a recommendation for much larger

[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXRPD2&P=0]http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXRPD2&P=0[/link]

goirish

Well I have not used that size so I can't comment on the preformance. I would think that it would lug it down. I know mine is happy with the 13/6. Vertical unlimited, slows for landing. Guess I will stay with that. If you use the bigger size, post the performance and let me know how it is working. Have a great day.

bingo field

You could always turn a 3 blade prop. I believe DaRock has a picture of his with a 3 blade on it and it looks terrific. A 3 blade will shorten the length of the blade by 1 in. If you would normally use a 13x6, with a 3 blade you would use a 12x6, and there is more clearance. Good luck!

hungryandbroke

I had a 14-6 and a 14-8 on my tiger 60 using a super tigre G90 and it didn't produce the speed I was looking for. Settled for a 13-6.

That 75 ax you have would swing a 12-6, 12-8 very easily.

I wouldn't even think of putting a 14 or 15 inch prop on that .75 engine you have. Why they recommend them for that engine I'll never know. The tiger 60 is not a 3-D plane but more of a larger aerobatic thriller that flys like its on a rail and very easy to land.

goirish

WOW!!! guess I don't know how to spell performancemy previous post is preformance. Does that mean before the formance.

bigedmustafa

My Feedback: (2)

Master Airscrew makes a nice 12x8 3-blade that should be a good match:

http://www3.towerhobbies.com/cgi-bin...&I=LXGYM8&P=ML

daveopam

My Feedback: (9)

13x6 would be my pick. I also like the MA better then the APC for this motor.

david

goirish

That is the prop that I am running on my 75. Great flyer.

da Rock

It's an odd combination, but it works EXCELLENTLY well.


The Tiger 60 has a bit of a clearance problem if you fly it with tricycle gear and especially if you fly off grass. I fly off of 3 different fields, all grass, and 13" worked best. 14" would work but was always knicking tips and those props ALWAYS carried a load of grass crap stuck to them. My models seldom need fuel/oil residue cleaning since I use extensions, but I was having to clean the crud off those props every couple of flights! PITA

When I tried 3 bladers, the Graupners I tried had too much blade area. They took a bit to wind up, but lost rpm every time they were loaded. In other words, vertical suffered and you could hear the r's drop off going over the top in loops. Too much blade or pitch or diameter will do that. Our glow engines have a relatively flat power curve, and once they're up into it, can handle a pretty wide range of props. But I never found a Graupner that fell into that range.

I tried Master Airscrew's recommended 3 blader for .71-.90 expecting that it'd also be too much, and was I surprised. They say to use an 11x8 (3) and I could find one. And it was nowhere enough prop. I had a 12x8 (3) that I'd tried on an OS91FX that hadn't been enough prop for it too. It was what MA had recommended for .90-1.08 and I'm running 14x7(3)s on 4 different OS91FXs on 4 different models with EXCELLENT performance, so I figured the 12x8(3) eventhough "too much" according to the mfg, should be at least OK. It wasn't enough prop either.

The prop you see in the picture is a 13x8 MA. Master Airscrew says it's best on 1.08-1.5 engines. I haven't found their advice to be worth spit. Nor have I found conventional model airplane wisdom to be worth spit when it comes to 3blade props. I don't think it ever was close to right because I've been seriously flying models since the 50s and never saw but a very few 3bladers ever used, much less for sale and readily available. Truth is, I can count on one hand the times I saw 3bladers for sale in LHSs back when there were lots of big LHSs. whatever...............

The Tiger60 you see get's a lot of work. Matter of fact, it'll be in the air in a couple of hours and will be up again on Friday, and this will be a slow week. The OS75AX on it has been a bull since day one. It's had a 13x8(3) on it for at least the last half of it's life. The Tiger and it's 75 started life about this time last year. It is a very good flying combination. All three combined.

I almost always wind up with "a lot of prop" on my models. I really like fan area. So for sure, my planes will have the most prop diameter their engines can swing. That often means that the engine can be heard to unload just a bit more slowly after takeoff than the average modelers' engines do. Ain't no big thing, but don't expect to tach big numbers on the ground. After all, we don't use our engine's ground performance. We use the performance in the air.

I've also run a 12x8(3) MA with decent enough success. But my prop testing includes a set of timed vertical climbs, and the 12" never hauls the load straight up that the 13" does. Fan size is probably the reason.

BTW, I never bother with hotter fuel than 10%. No real value.

Hope this helps.

da Rock

BTW, I've been asked many, many times how I get "the wrong prop" to work as good as I do all the time.

First answer is that a lot of mfg's numbers are just their best guess. Second answer is that most of the rest are bad guesses. Third answer (and probably a the closest to the truth) is that mfg's numbering haven't been updated since day one. And chances are good that none of the mfg's have recently tested on the real models that're being flown today.... and they don't need to.

Every time any modeler has actually realised that I just said the prop on my Tiger60 has an 8" pitch, they've asked how the devil I get the airplane to land so slowly. I usually start the answer with the sentences in the above paragraph. And if they're still around when I get to it, I try and explain about blade area.

Lot's of things about props are really fun to talk about. And about as applicable as the one, "a 3 bladed prop isn't as efficient.... etc etc"

Bax

My Feedback: (11)

O.S., like a lot of engine makers, suggests propellers that will allow the engine to run well and also give low noise levels. In Japan, and many other parts of the world, modelers are under heavy noise restrictions. Larger, low-RPM props help keep noise down. That's why you see such large props in the instructions.

The O.S. Max .75 AX can easily turn in the 12,000's. Propping it for 12,000 to 12,500 RPM when leaned to just rich of peak RPM on the ground won't hurt it a bit, and will really unleash some power. You'll also get quite a bit more noise than when you use a recommended propeller. We'll use a 12 x8 or even an 11 x 9 or 10. Try an APC prop, too. Different makers have different airfoils and profiles for their props, which can make for widely-varied results, even when the props are supposed to be the same size.

Bob Mitchell

I'd like to see it too. I've got a Sig 4* on the way and ordered 14x6 and 14x8 based on OS's recommendation.

Edit: The OS website has a link to 2 product reviews, one here on RCU the other on RCG. The RCU reveiw broke in with a 14x6 and flew with a 14x8 and was amazed at the vertical performance. He tached it at about 9100. Seems low to me.

The other review got essentially the same rpm but in addition has a table with different prop sizes and rpm's. He concluded that it should be a 13x6.

hungryandbroke

The only way you will ever know which prop works best for YOUR style of flying using any certain engine is to try different ones and find out. Actually it's sort of fun to see the difference one prop makes compared to another. Just ask your buddies at the field if you can try one of their props so you don't have to buy so many to find the right one for your style of flying.

Buying a tachometer isn't a bad idea either...or use your buddies.....

Since I have you borrowing your buddies props and tachs, ya might as well see if you can use their fuel too!

One thing you've done right so far was to get yourself a Tiger 60!

good luck

paully_321

Thanks for the suggestions!

I bought two MA 13 X 6 today. I'm gonna start there.

Maiden coming soon! Don't know if I'll tackle that myself though.

Paul

hungryandbroke

Paully_321

Before your flying career is over try an APC or Graupner prop. You'll be glad you did. MA's are ok but have a tendency to flex more than the above mentioned props and they will give you more RPM's than the MA. Plus, you're engine will be happier!

Have fun! The tiger 60 will make you look like a professional. Your buddies will think you went to some kind of RC Flight School....

Cyclic Hardover

My Feedback: (3)

Consider the 12/6. It all comes down to what type of flying your going to do and what you expect out of it. It's a Tiger, not a 3d. Whatever you pick,leave iton for many flights. Then whenyou decided to change, the performance will be instantly noticable either for better or worse. If you constatnly change props, you never know where you are on it all

ErikElvis

My Feedback: (2)

Definitely Try a 13X6 or right around that area. Im sure you could even drop to a 12x8. My 91 surpass reccommends a 12x10 up to a 14x6 I believe. Just buy a couple and play with them.