CitatioN10

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OK i did a search and looked though 7 pages and didnt really find what i was looking for . I have the NexSTAR with the .46AX engine. Last sunday i smashed the plane so i took the engine apart and cleaned it so on so on . .Anyway i replaced the plastic 10x7 prop with a WOOD 10x7 Prop , Today i took it for a flight and i seen a big diffrence on the sound of the engine and the performance as well . Either something is seriously wrong with my engine . OR thewre must be a big diffrence going from Prasic to Wood prop ? ? Engine runs fine but i swear something is ODD here ..


Thanks in advance
CitatioN10

Fort Myers Florida

JohnBuckner

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A 10x7 may not always be a 10x7. Particularly with wood props if you put them on an accurate pitch gauge they can be as far off as a half inch in pitch. The same also applies to a lessor extent to moulded props. Not normally such a big thing as long as your engine runs well and the airplanes perform properly.

Now the sound is another huge can of worms. Simply put the materials used in the prop, blade pattern, diameter, tip design, airfoil and thickness ratio is going to have huge effect on how the prop sounds. Once agine not a major problem unless performance is severely affected.

On a trainer being used as such I normally reccomend the Black Master props, Although these are most flexable and will have more performance losses from this they will also survive more minor ground strikes. APC and Bolly are stiffer and generally have better performance but both are not as durable in ground strikes. It is interesting though in the case of APC due mainly to tip design they are quieter than the standard Master. Wood props are generally a bad bet in the training environment if only for the reason that at the slightest touch of a blade or rock is going to make it unsafe to use. Arguments could also be made that composites could be made thinner for more performance than a wood blade however this is not always the case.

Propellor design is 75% science and 25% whitchcraft.


John

JohnBuckner

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DP

bryris

A post so nice, he did it twice.....

JohnBuckner

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It must have been the witchcraft part that caused the DP

CitatioN10

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Thanks a lot for the reply , I will see if i can pick up a 10x7 APC and give it a try , I was really thihking i had engine issues as my friend fired up his nexSTAR next to mine with his being the master prop vs my wood one.

MinnFlyer

My Feedback: (4)

Citation, Don't worry about getting an APC. As long as you're in the trainer stages, one prop is as good as another, so as long as you'll be breaking a few, buy cheap ones.

Lightfoot

My Feedback: (1)

I would be more concerned with the sound difference being a product of having taken the engine apart rather than the difference in the prop. I watched a guy in our club change props in an effort to tweak the performance of of his GP Extra 300. He used different types and pitches of plastic and wood props and there was little difference in the sound other than the expected change in RPM due to changes in diameter and pitch. It is highly probably that there is a significant difference due to change in your needle valve setting after the cleaning rather than changes due to prop material.

Geistware

My Feedback: (16)

Plastic propellers are usually more efficient than wood propellers but this is not always true.
APC propeller are usually the most efficient propeller that you can purchase under 20 inch diameter.

-pkh-

My Feedback: (2)

I agree with Lightfoot... a change in sound is more likely due to something goine wrong with the disassembly/reassembly. I think you might get more vibration with a wood prop if you don't balance it... I believe the APC and Master Airscrew props come pretty well balanced from the factory.

If you're just starting out... Master Airscrew props are the way to go... they survive prop bumps better than APC or wood...

NJ Flyer 72

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I used a wood Top Flite 11x6 Power Point Propeller on my NexStar, but i really didn't notice a difference in performance compared to the stock plastic propeller it came with.

CitatioN10

My Feedback: (1)

I did the prop change just 20 minuites ago , the airscrew flat out SCREAMS on my .46AX , to HE%% with that wood one .

Fastsky

The MAS will allow the engine to speed up more because as the prop turns faster it will flex in effect making the prop grab less air. This is where the inefficiency comes in. If you look carefully as you throttle up, you can actually see the blade flexing. Wood props and APC props don't flex. When you throttle up with an APC or wood prop more air is being pushed which puts much more load on the engine. The engine won't be able to turn as fast as with a MAS prop but it will still be moving more air. The lower rpms also mean lower noise levels. [8D]

JohnBuckner

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I beleve CitatioN10b just reproped from a wood to an APC not a Master.

-pkh-

My Feedback: (2)

...and it's this flexing that makes the Master Airscrew props more resilient to prop bumps. I have a couple of belly landed planes that I try to keep Master Airscrew props on, just in case the prop doesn't completely stop horizontal before landing.

APCs seem to perform the best for me, and they are more durable than woods, so when you get your landings down, and don't bump your prop so much... APC's the way to go IMO...

I don't see much economy in wood props, personally... the APC and MAS props are only a little more $$, and they always seem to last at least twice as long!

CitatioN10

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No i went to a master

JohnBuckner

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Misunderstood your prior post but that cool and it is an appropriate prop, enjoy.

John

britbrat

The Nexstar RTF comes with an OS FXi engine and Hobbico recommend an 11-5 prop. I agree with them. A 10-7 is not a great choice for a large slow model.

WRT the wood vs plastic thing, A wood prop will necessarily be thicker than most equivalent plastic props & will have more parasitic drag -- thus it will probably rev a bit slower, produce less thrust & will have a different sound (usually a lower pitched note). If it has similar thickness, it will be too flexible & will flatten out as RPM & power increase -- leading to higher RPM, more noise & less go.

CitatioN10

My Feedback: (1)

Well it files 100% better with the 10x7 then it does the 11x6 or 11x5 , i have flown all the props and im loving the 10x7 , just because the company recommends a specific prop doesnt mean its always the best . Thats why people mod things .

-pkh-

My Feedback: (2)

The guys I know with OS .46AX/FX engines typically fly 10X7 props... I fly 10x8 props on my OS .50 SX engines...

Cazarak

this has to be the most intelligent post on the whole forum

it probably matters in pylon racing but general sport flying the best rule of thimb is if it flys,,,,fly it..