Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

OS VX-DF prop?

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Old 11-01-2007, 03:58 PM
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vasek
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Default OS VX-DF prop?

I have a new .40 VX-M (same as VX-DF but with water cooled head) and i was told the best way to break it in is to run one tank on the stand to get the required heat to mach properly the piston/ liner

What prop would i be using? don't want to pay a fortune since is for one tank break in only, but dont want the prop to break on me either[X(]

if one could be found on TH pages please post the link

thanx,
Vasek
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Old 11-01-2007, 04:25 PM
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Default RE: OS VX-DF prop?

Generally you want to use one size smaller than what you intend to run and then run it at the target RPM. This will underload the engine and it will be rich.
I have not had that engine but first you need to know what RPM you are planning on running it at.
I am going to guess and say to start with a 9-6 cut down to maybe 8-6. Lean the needle until you get around 17,000 and let it run rich like this. Hopefully someone else will chime in but this will be your procedure.
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Old 11-01-2007, 05:28 PM
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Default RE: OS VX-DF prop?

Practical RPM Range: 2,500 - 28,000

so if I want to break it in like i do my Jett engines, i should be turning around 27 K -28 K a little rich on (as you said) one size smaller prop

the prob is this is a marine engine (it will power a boat) so i have no idea what size the prop should be in the first place PLUS don't know any prop sustaining 27 K RPM's[X(]

i need some help pls
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Old 11-01-2007, 06:19 PM
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Default RE: OS VX-DF prop?

Your peak HP is at 23,000 rpm so 28,000 may be higher then needed for break in. A Q40 prop should work.
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Old 11-01-2007, 10:04 PM
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Default RE: OS VX-DF prop?

vasek

Yes, a Q-40 prop should work fine, but be safe and get one of the carbon fiber apc props. You may have to call apc for this if not on their list. They are available for more money of course, but the added safety is worthwile. Ever seen a blade shed at high rpm, flat scary. ENJOY
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Old 11-02-2007, 12:23 AM
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Default RE: OS VX-DF prop?

what size is a Q-40 prop?
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Old 11-02-2007, 12:32 AM
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Default RE: OS VX-DF prop?

In the 7.4 x 8 range.
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Old 11-02-2007, 12:56 AM
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Default RE: OS VX-DF prop?

The highest load quickie carbon props APC has is a 7.8x7 or LP 74825C (7.4x8.25) On Power Master Heli 30% and a correctly set tuned pipe the OS 46 VX DF should turn the 7.4 x8.25 prop at 24,500RPM on the ground(after break-in). With the header/pipe set longer it should turn a pylon 8.75x9.5NN or 8.8x9.25 at 20,000RPM. Ream out the prop to fit the short shaft addapter (Tru Turn part number TT-0141-A) that you will need. Don't use a prop with less load or sport prop, IT WILL THROW A BLADE! Stay inside rpm limits and always keep anything you care about out of the prop arc. I don't know if it's a good idea to run a air prop on an engine with a marine head thats air cooled only. Adding water? Perhaps.

See the Peformance Specialties break-in info. http://www.pspec.com/breakin.asp Seems to work for every engine Iv'e tried. You don't need to cut the props listed for this engine. Three or four tanks worth is should do it for this engine . Don't run it too rich, just wastes fuel and could hurt the con rod. Engines need some heat to seat.
I start with Power master Heli 15% /20, I like the extra oil.
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Old 11-04-2007, 02:49 PM
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Default RE: OS VX-DF prop?

thanx freak!
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