LargeScale88

Hello,

I found master airscrew 3 bladed prop 14x8 size, brand new in package, bought it, to test on a saito 100 for a plane. The package said factory balanced, but I checked the balance anyway, and it was fine. So I mount it to the engine, fire it up, and its shaking like crazy. If you look down the line of the prop, it aint turning in a straight line. I shut the engine off, and took the prop off. (Engine was on a test stand, everything was mounted tight).

It seems like MA props are realyl flimsy. I have graupner 3 blades, satisfied with those, but they don't have the size I need. They do have a 14x7, which Iwant to try.

The whole point of this thread, what do other people think of master airscrew 3 bladed props? and 2 bladed? Flimsy? Junk?

Any other 3 bladed props out there besides graupner? Another quick question.. Graupner props are grey, but I want them black. Can I paint them? What paint?

Thanks

da Rock

I run 14x7(3) on OS91FXs in my P47, Corsair, Spitfire, F6F, and Sukhoi. They pull excellently well. As you would with conventional gear, I've had at least a couple of slight prop hits this summer. Inspection afterward showed the tip paint was chipped but no other damage. They've held up since day one.

Funny you mention Graupner. I've just dug out a 12.5x7(3) I've had for a couple of years and am about to test run it on a 75AX in and Extra300 that flew with a MA 12.25x8 the last 4-5 flights. The MA was trimmed and balanced to help the original engine in that plane get better rpm. That engine was an OS61FX which I just retrofitted with the 75AX.

Notice the engines I'm running and the MA diameters and pitch numbers. All are 2cycles and except for the 61FX probably more powerful than the one you're testing.

LargeScale88

Did you do anything special to those master airscrew 3 bladers you got? Out of the package and in the air? Why would mine shake terribly bad?

da Rock

BTW, my somewhat oldish list of prop recommendations for engine sizes that came off a MA package some years ago (and that has this at the top: Master Airscrew 3 Blade Series Propellers ) doesn't list a 14x8 on it. It lists all the 3 blades they made a couple of years ago. They've added 10x5(3) and 15x7(3) since then.

Also, Tower doesn't list one now or in last year's catalog either. You sure it's a 14x8(3) ?

LargeScale88

Did you do anything special to those master airscrew 3 bladers you got? Or right out of the package and running on the airplane?The package says factory balanced, but it sure doesn't run balanced to me. It shakes the whole airplane apart. What could my problem be?

carrellh

Some plastics can be dyed with dye made for clothing
http://www.ritdye.com/dyeing-techniques/stovetop

LargeScale88

da rock: Yeah, the package and prop say 14x8, and its a 3 blade. I'm still trying to figure out why it shakes so bad. Maybe a bent shaft on my engine? It was in a slight crash a couple months ago, very slight, and I've ran it sense then, it runs smooth. Any help on the prop?

Carrelh: Thanks for the link. Thats a fantastic idea.

da Rock

The old packaging and the new (just bought last week) packaging don't list your prop as one Master Airscrew makes... or at least sold or sells in MA packaging (old and new packaging) in the US.

The packaging also has the prop's dia/pitch printed inside the plastic that seals the prop and packaging.

The prop has some glue to hold it centered in the sealed plastic bag.

LargeScale88

Ok, don't call me dumb, but I went to double check, and its a 13x8 3 blade. One number off... My bad.

LargeScale88

How would a graupner 12x8 run on a saito 100? Graupners are wide blade soI think its a good match.

da Rock

They apparently haven't made or marketed that prop dia/pitch.

I'd say there is a possibility you bought a counterfeit.

There is nothing about the dozen or so Master Airscrews I've bought over the last 6 years that would suggest a problem with the brand.

Why does your 4 cycle shake so badly? Take a look at the back of that package and look at the size prop MA recommends for a .90-1.08 displacement 2 cycle. That package did have a bunch of info on the back didn't it?

4 Cycles are known for two characteristics. They shake more than 2cycles and if overloaded are very apt to react badly.

da Rock

The last time I ran a 4cycle (I don't use them very often.), I made a mistake in handling and it beat itself to death.

OK, I'm making fun, but that is actually true..... except for the phrase, "the last time I ran a 4cycle". In truth the last time I ran one was when I bolted on the new replacement the mfg sent to replace the one that beat itself to death.

I'm not sure, but I think those engines were predetonating, both of them, the old and the new. They did not like something about the way they were mounted or the way I looked at them or something. The reason I mention this isn't to add more levity, but to describe an example of what 4 cycles can do.

They vibrated badly. In both cases, they were spinning an APC two blade that before and after spun happily on other engines. They also did not like the Top Flite I used to replace the APC. I was trying everything to figure out how to use the 4cycles. Plus and APC just looks dangerous, and a wooden TF seemed a safer thing to have on. I believe those engines were predetonating for whatever reason and they most certainly shook.

The engine problem turned out to be a mounting problem that was not a problem with the engines I swapped into their place.

da Rock

A 12x8(3) is going to be a better choice than a 14" diameter, at least a better bet for a test. Your Saito is probably about as powerful as the 61FX/75AX averaged.

I found my OS61 two-cycles worked very well with MA 12x6(3). If you look at the blade area of MAs, they look to have the total blade area of wide two blade props of the same diameter. Graupners have at least half again that blade area.

I'd bet the Graupner you have has a fair chance of working on your engine. But it has to work on the engine when it's on the airplane. And it'll depend on the airplane being light and clean for that much blade area and pitch to work with both engine and model.

BTW, I've found no real parallel with the published pitch of 3 blades versus published pitch on 2 bladers. So I don't even consider the published pitch when looking for 3 bladers to test on a new model. The blade areas seem to matter 100% more.

da Rock

Not "bad".... human.

I've run a 13x8(3) Master Airscrew for a couple of years on an OS 75AX with more than excellent results. I actually run it "alternately" with another 13x8(3)MA that I turned into a 12.4" prop. Some "thin" days the full size would work the air better than the cut down. On heavy days, the cut down let the engine turn up.
(I mention this to put some perspective on the suitability of a 13x8(3) on a 75AX. The prop is good on hot days, but close to too much prop on cold days that have high pressure.

If your Saito is a bull, that Graupner might be a good producer. But it's got lots more blade area for the engine to spin. What altitude is your flying site?

da Rock

If your 12x8(3) Graupner seems to be too much load for the Saito, if I were you, I'd take the 13x8(3) MasterAirscrew back, tell them what it was doing and see if they'd swap it out for you. And see if they'd get you a 12x8(3) or 12x6(3) for the replacement. If the Graupner was too much load but not way too much, less blade area could give you a sweet running prop.

It's pretty amazing to me to have finally found MORE THAN ONE 3-blade that can be tested on an engine. There are so few made, and so few sizes, it's almost impossible to have any choice.

Good luck.

TFF

Measure the track of the blades; if each blade does not measure the same distance from the firewall or measuring point when each blade is in the same place either the prop or shaft is bent, unless the whole is not centered. MAS makes good props but that does not mean you cant get a bad one that got away.

LargeScale88

The airplane is a Great Planes Extra 300 .60 size, about 8 pounds. I'm just wondeing now if I should buy a 2 stroke. I have the saito 100 with the slimine pitts muffler, and I'd hate to spend more money. I'm debating now whether to just use a zinger pro wood 14x8 2 blade instead of farting around with 2 blades, as they seem to be a hassle. If I do go 3 blade, it will most likely be the graupner, as I've heard good things about them.

What about MA 2 bladed props? Will they shake as bad as my 3 blade on my saito100?

Thanks for the replies!

da Rock

My Extra300 is 6lb 15.5oz, or was with the OS61FX on it. It flew very good with a number of 2 blades. If I remember correctly, the TF wood was the best 2 blade. A MasterAirscrew 2 blade was just as good. Then I decided to quieten down the sucker and tried a 3 blade. Truth is, the spinner cost and the risk you take when you have only one prop to choose from.......

Heck, you've got two dozen 2-blades that are good bets and will all fit the same spinner. Give the Graupner a shot but test more than one or two 2 bladers too.

It sounds like you're hoping someone can tell you the perfect prop for your plane. Too many modelers think there are magic props, try what someone tells them is the perfect one for their airplane/engine, and never try any others. They then pass the advice on. Props don't work that way. As long as we hang the huge range of models on our engines, there won't ever be "the perfect" prop for say your Saito100.

Phoenixangel

I have a p-51 that the pts 3 blade prop done the same thing. One blade was way out of line nearly .5 of an inch....It was the spinner backplate not the prop. New spinner and it was perfect.

EJJK

If your 3 blade prop is definitely balanced and you crankshaft runout is

mike31

My Feedback: (67)

I have run MA props for years both 2 and 3 blades. Never had a problem. Although, I prefer wood props generally, MA props are always on hand.

mike31

My Feedback: (67)

Props don't shake if they are balanced properly!

ArcticCatRider

My Feedback: (6)

The quickest way to rule out the prop versus the engine/possibility of a bent crank is to run another prop on there. One you know to be good.

If the shaking isn't so violent after the switch, you can condemn the 3 blade prop. Otherwise, you'll need to check the crank with a dial indicator, work on your mixtures, check bearings, balance, spinner..etc.

I don't really have any complaints about MA props. They seem to be a little louder than APC props....I haven't really compared with Zinger

LargeScale88

So thats why I was thinking of going to Zinger pro wood. The curved tips of the prop make it get more RPMs, so what i hear....

I've never liked APC props, but they are good props.


Another example: When I started flying years ago, I had a sig kadet lt40 with os max 46. I had a master airscrew 10x6 on there, balanced, shook the plane to pieces (not literally). I swapped it with a zinger 10x6, balanced, and you could put a glass of water on the plane and not see a ripple when the engine was running. I'm sticking to wood. No 3 blades, I've made up my mind. Too much hassle. Especially sense they have a hefty price tag, some of them, you buy one, try it, doesn't do the job, set it aside, try another, ect. Wood props are cheaper, and tougher in my opinion.

Jetdesign

My Feedback: (8)

I hate master airscrew props because of how much they flex when you accelerate. So far I've liked Graupner props, Xoar props, the Chinese Xoar knockoffs, and I use lots of APC props.

Don't forget to balance your hub and not just the prop blades.