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 .25 vrdf Carbon fibre prop?

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Old 04-04-2009, 10:51 PM
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Default OS .25 vrdf Carbon fibre prop?

Just wondering about prop size for a OS .25 vrdf, and whether it should be Carbon fibre or wood, if carbon fibre where do you get them,
I want to put it in my Shrike.
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Old 04-04-2009, 11:03 PM
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Default RE: Prop size OS .25 vrdf

I would start with a 8x5 or 8x6. If the plane is clean and light, then look at APC's entire inventory to see if 7.5x6 [or so] props are available. You might even get it to pull a 7x7 after a dive.
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Old 04-06-2009, 11:54 PM
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Default RE: Prop size OS .25 vrdf

Where do you get carbon fibre props for an engine like this?
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Old 04-07-2009, 12:42 AM
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Default RE: Prop size OS .25 vrdf

Look up Steve Wilk at Eliminator Props.
Unless your engine can deliver RPM exceeding 190,000 divided by prop diameter, APC will do just fine.
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Old 04-07-2009, 08:37 AM
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Default RE: Prop size OS .25 vrdf


ORIGINAL: smoknrv4
Where do you get carbon fibre props for an engine like this?
Apart from Eliminator Props you could also try ZZ props (both on http://www.clspeed.com/parts.htm) and Supercool Props http://www.supercoolprops.com/

P
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Old 04-07-2009, 12:08 PM
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Default RE: Prop size OS .25 vrdf


ORIGINAL: combatpigg

Look up Steve Wilk at Eliminator Props.
Unless your engine can deliver RPM exceeding 190,000 divided by prop diameter, APC will do just fine.

An APC prop would be great to use alot cheaper and readily available, i just wasn't sure with a ducted fan engine what was appropriate, it'll be the first time using one in a prop application, thanks for the info guys.
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Old 04-07-2009, 01:13 PM
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Default RE: Prop size OS .25 vrdf

If you really want CF, APC has these pylon props, which could be trimmed down to bring rpm up. Dunno how stupid big the hub is though.

7.8x6 Carbon Fiber
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Old 04-08-2009, 10:06 AM
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Default RE: Prop size OS .25 vrdf

Trimming props is something i've never done in all the years I've been flying fast, I guess I could try it.

An Apc nylon prop is what I'm going to use, I just thought it might be a safety concern for a ducted fan engine, thats all, I have read some stories.

By the way I realize there is a difference between the OS .25 FX and the OS .25 VRDF, I just want to hear some imput on that, say for a SHRIKE, DIAMOND DUST ETC........

Thanks
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Old 04-08-2009, 10:08 AM
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Default RE: Prop size OS .25 vrdf

Maybe Bob27s has something to say about this.
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Old 04-14-2009, 11:05 PM
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Default RE: OS .25 vrdf Carbon fibre prop?

as far as safety, you will be fine with the apc or master airscrew props at these rpms, but if you would like some reassurance use apc's formula to check for rpm safety, i have untold hours of operation on k&b 3.5 engines and os vrdf .25 engines, with 7" inch props and never a failure, my k&b ran better than 24,500 static on 7x6 master airscrew props, this was with the wizard setup, and perry .40 carb on sport fuel and k&b 1L plugs, the kress fans use a material nearly identical to the master airscrew props[>:]
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Old 04-15-2009, 06:02 PM
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Default RE: OS .25 vrdf Carbon fibre prop?


ORIGINAL: lfinney

as far as safety, you will be fine with the apc or master airscrew props at these rpms, but if you would like some reassurance use apc's formula to check for rpm safety, i have untold hours of operation on k&b 3.5 engines and os vrdf .25 engines, with 7" inch props and never a failure, my k&b ran better than 24,500 static on 7x6 master airscrew props, this was with the wizard setup, and perry .40 carb on sport fuel and k&b 1L plugs, the kress fans use a material nearly identical to the master airscrew props[>:]

Thats good to know, thanks
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Old 04-15-2009, 08:51 PM
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Default RE: OS .25 vrdf Carbon fibre prop?


ORIGINAL: lfinney

as far as safety, you will be fine with the apc or master airscrew props at these rpms, but if you would like some reassurance use apc's formula to check for rpm safety, i have untold hours of operation on k&b 3.5 engines and os vrdf .25 engines, with 7" inch props and never a failure, my k&b ran better than 24,500 static on 7x6 master airscrew props, this was with the wizard setup, and perry .40 carb on sport fuel and k&b 1L plugs, the kress fans use a material nearly identical to the master airscrew props[>:]
So evidently messing with clipped 7" MAS props running at low-mid 20's is not a prob. Good to know as I was about to do that.

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Old 04-16-2009, 06:32 PM
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Default RE: OS .25 vrdf Carbon fibre prop?

BTW the os vrdf .25 was running a 7.5x6 at 25k plus rpm on sport fuel, if you are running the ops .15, i would be using 6" ish wood props or the like, or grab some of the fast combat .15 props
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Old 04-16-2009, 09:28 PM
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Default RE: OS .25 vrdf Carbon fibre prop?


ORIGINAL: lfinney

BTW the os vrdf .25 was running a 7.5x6 at 25k plus rpm on sport fuel, if you are running the ops .15, i would be using 6" ish wood props or the like, or grab some of the fast combat .15 props
On this topic, those Graupner Speed props, the black glass reinforced nylon guys but not the CAM props, for example the 6x5.5 - are they intended for IC or are they electric only? And are the Graupner grey nylon 6x5, 6x6 too wimpy for that engine? I imagine the OPS .15 is no slouch, but I haven't run it yet, waiting for the pipe to arrive. Anyone know what I should expect from it, is it a dated QM .15 contender or..?

I have a wooden 6x4.5 too, but for some reason it looks too big for a .15.. [sm=confused.gif]

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Old 04-17-2009, 09:01 AM
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Default RE: OS .25 vrdf Carbon fibre prop?

the gray graupner is fine used alot of them no problems at all, they have more area out towards the tips, and can actually load the engine more than one would think, i would on initial start up look for about 25k rpm till you get a few tanks thru the ops, then start aiming for the high 20's the qm .15 rossi's were turning 30k propped right for racing on the ground. do you have your pipe for this motor yet? if i remember correctly the rossi used 6x6 props thinned and narrowed.
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Old 04-17-2009, 10:14 AM
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Default RE: OS .25 vrdf Carbon fibre prop?


ORIGINAL: lfinney

the gray graupner is fine used alot of them no problems at all, they have more area out towards the tips, and can actually load the engine more than one would think, i would on initial start up look for about 25k rpm till you get a few tanks thru the ops, then start aiming for the high 20's the qm .15 rossi's were turning 30k propped right for racing on the ground. do you have your pipe for this motor yet? if i remember correctly the rossi used 6x6 props thinned and narrowed.
I have a MACS 1110 on order and should show soon. I hope it's a decent choice..?

What nitro content would you think this motor is intended for out of the box? Looking at the rod and general construction, this thing seems like it could run 30k all day. The case is closer to .25 size than .15.

My guess for first runs would be to run the grey 6-5 or a clipped MAS 7-5 or 7-4 and tach it at a rich but fast 2-cycle in that 25k regime you suggest.

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Old 04-17-2009, 02:16 PM
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Default RE: OS .25 vrdf Carbon fibre prop?

Hi!
I would go with an APC 7x6 prop! Expect around 25000rpm with long pipe and 80/20 fuel (FAI).
A good airplane is a good old fashioned QM racer, like a Little Toni, with a wingspan of 110cm . Expect a speed around 200-220km/h.
APC is the prop of choice if you want best performance,
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Old 04-17-2009, 05:25 PM
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Default RE: OS .25 vrdf Carbon fibre prop?


ORIGINAL: jaka

Hi!
I would go with an APC 7x6 prop! Expect around 25000rpm with long pipe and 80/20 fuel (FAI).
A good airplane is a good old fashioned QM racer, like a Little Toni, with a wingspan of 110cm . Expect a speed around 200-220km/h.
APC is the prop of choice if you want best performance,
Thanks! I have a QM racer for it, a Matney AJ-2. Now one thing though - this is the side exhaust engine (I wish it was rear) with Perry carb. I think I ought to pull the carb and install a venturi. Any idea how much performance will suffer with that carb? I haven't found mention anywhere of this engine, except in the OPS literature, so have no info to compare.

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Old 04-17-2009, 10:18 PM
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Default RE: OS .25 vrdf Carbon fibre prop?

the 1110 pipe is on the money for performance. i dont know the neck size of the ops .15, but i went from the stock perry ,to a .40 perry and the neck size was the same but gained venturi ID. i drill and tap the header plate for pressure, i never tap the tube or the pipe, the tubes will crack or strip. i never have throttle issues with this method. no reason why you cant just use a fuel shutoff. do you have a venturi for the ops? its worth at least 1-2k rpm. the rear exhaust ops .15 go for crazy money.......on fleabay......
the nitro at 15% will do fine, if you have heads shims......[>:] you can go crazy, but 30k plus on 15% with a pipe is cheap thrills!
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Old 04-18-2009, 09:01 AM
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Default RE: OS .25 vrdf Carbon fibre prop?


ORIGINAL: lfinney

the 1110 pipe is on the money for performance. i dont know the neck size of the ops .15, but i went from the stock perry ,to a .40 perry and the neck size was the same but gained venturi ID. i drill and tap the header plate for pressure, i never tap the tube or the pipe, the tubes will crack or strip. i never have throttle issues with this method. no reason why you cant just use a fuel shutoff. do you have a venturi for the ops? its worth at least 1-2k rpm. the rear exhaust ops .15 go for crazy money.......on fleabay......
the nitro at 15% will do fine, if you have heads shims......[>:] you can go crazy, but 30k plus on 15% with a pipe is cheap thrills!
This one cost me $100, NIB (real NIB, not old in a box like so many!), but I am happy to pay that for an OPS anything. I'll have to live with the side exhaust. External pipes are only good for oohs and ahhs in the pits by the OSclone+ARF fliers, i.e. they look cool.

It appears to be built like a car engine so I have no doubt it really doesn't care if it runs 25-30k. Ought to sound like a demon on the open pipe. Wish it was RIRE though.. [&o]

I don't have a venturi but I can easily machine one. I'll just run it as is for now, then I can drop in the venturi once I've finished with the Perry shut-off valve aka carb. I have a couple of other carbs too.

I figure the OPS should be enough power for a 24" span SWR delta weighing in at tops 24-25 ounces, which is half done right now. [>:] It won't outturn the QM but it ought to go like a raped ape in the straights. I might have the QM together for late June. Although.. I am considering dropping in an Orbit 15-12* ([X(]) and getting another QM down the road for the OPS.

MJD



* No, you merciless Revver lurkers out there in the peanut gallery, I haven't gone soft . I have to use it on something or flog it, it's too expensive to lie around and I stole the pylon model for the .65 you see.. it's all in the name of speed and stupidity, no worries! And it fits perfectly in the nose. Gonna need a lot of pitch though.
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Old 04-18-2009, 10:15 PM
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Default RE: OS .25 vrdf Carbon fibre prop?

makes my ears ring and ache just thinking about it
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Old 04-18-2009, 11:25 PM
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Default RE: OS .25 vrdf Carbon fibre prop?

ORIGINAL: lfinney

makes my ears ring and ache just thinking about it
I was thinking about the pitch speed of a .15 spinning a 7-6 APC at 25k.. [:-]

Seriously, will it really do that? I'm sounding like a noob, but not really dude.. but yes, in that I have not owned or opped a seriously high performance .15 before. I got this one sometime in the winter on you know where. Luckily it is the real McCoy as in NIB. Must not have been my day for a scam (thanks bud!). I have a few vintage FAI .15's in my collection, yes, but all second hand and no ABx. And living where I do, I've never seen anything but Q500 live, though did see some FAI combat from a distance somewhere and was blown away by the sound live. I had to stay where I was for some reason so could not get close, must have been at a vendor booth - mustard, ma'am? Where did that brain cell go.. [8D]

The only fuel I have on hand is my standard 15% nitro, 18% 80/20 syn/cas. I have castor. Of course OPS says run 75/25 FAI fuel. If I feed it a diet of 15% all it's life, what's your call on total oil and makeup for a long happy life for us together? SHould I wait for the pipe to arrive, or can I safely let impatience and raving mad curiosity take over my brain and run it on the test stand tomorrow with an open header and 7-6? I reallllllly want to hear it run, and I might dance around it a bit before the neighbours accost me. Luckily the one to the east is 94 and stone deaf, and her 60-something daughter must think I'm cute and never gets upset about anything. Yet. I was planning to run my small pulsejet tomorrow too.. hmmmm. Mebbe back in the ball diamond would be better.. . But yes I will video it all, promiose.

The engine is a Doylejet, which dimensionally is the same as a Dynajet and uses identical reeds. Runs on naptha with the stock jet, and of course you can open that up to your heart's content depending on the fuel, if you know what you are doing of course. I just bought an air compressor (finally... wheee!) on sale, and what better way to celebrate than to invite over a few buddies and fire up a pulsejet over beers. Good neighborly fun.

I originally bought the Whiplash for this.. really. I was going to mold a nose cone for battery, and run a 8 oz. bladder tank. And I am convinced it will work fine. Then I changed my mind and started building something else and never finished it. And planned to horrid things with OPS engines on the Whip.. then got PO'ed and tossed it out back when I discovered it was warped beyond reason. Now that I have cooled off, I will try the heat gun trick, and if it straightens out enough.. I could finish the conversion in something like 12-15 hours works I think. And that ain't a lot. Cackle.. [>:]

Man, OT it is! But so what it's all fun around here.

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Old 04-18-2009, 11:33 PM
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Default RE: OS .25 vrdf Carbon fibre prop?

I just realized that if I can straighten it out, I could have this done for the NC speed rally. Seriously. The stars might align yet..

Looks like the site ain't much of a fire hazard. Or a magnet for noise complaints either!
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Old 04-19-2009, 06:03 AM
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Default RE: OS .25 vrdf Carbon fibre prop?


ORIGINAL: MJD


I was thinking about the pitch speed of a .15 spinning a 7-6 APC at 25k.. [:-]

Hello,

a 7x6 is way too much prop load for a high timed .15 (OPS, ROSSI, PICCO, etc). You won't achieve 25K...

The APC 7x6W for instance is a well working prop for the JETT BSE .25 or the OPS .29 RIRE to achieve about 23K static.


A good prop for the OPS .15 with 1110 MACS pipe would be the black Graupner 6.5x6.5 speed prop!



But it should be shortened to 5.5" in diameter to reach 25K plus rpm in flight. So your flying prop will be a 5.5x6.5 Graupner Speed Prop preferably.

Start with a pipe length of 25 cm and cut the header at 0.5 cm steps (about 21 cm of pipe length should be correct, depending on the exhaust timing). Use a test prop for the tuning procedure on the ground (Graupner 6.5x6.5 speed prop cut to 4.5x6.5). The aim is to simulate the unloaded rpm already on the ground for sophisticated propeller and pipe length tuning.

15 % nitro fuel will be be OK with the OPS .15. Just add a head shim (from another .15 engine if needed). The oil percentage should not be lower than 20% to protect the lower conrod end from getting too hot.



ORIGINAL: MJD
I could have this done for the NC speed rally. Seriously.
So what will be your speed plane setup(s) for the Carolina speed event in June? We should keep in mind that the maiden flight should not be during a speed event.
http://www.rcuniverse.com/forum/m_8615935/tm.htm

P.S: Next weekend there will be an interesting R/C speed event in Californa. Although I suspect it won't be FAI legal [&o], there will definitely be very fast speed planes ... [8D]

http://www.rcgroups.com/forums/showt...9#post12017253




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Old 04-19-2009, 08:34 AM
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Default RE: OS .25 vrdf Carbon fibre prop?

[link=http://www.rcuniverse.com/forum/m_8664081/tm.htm]Crater maker[/link]

I am hoping to have this conversion ready, it should not be too difficult a project to have ready by then. While I am picturing the engine upright here, the layout will work nicely with the engine inverted and leave the top contours smooth. Of course the cowl has to be tough enough to serve as landing skid, but I don't think that is hard to achieve.

The fuselage fits perfectly a Jett 8 ounce bladder tank, which should give me two minutes of blasting around. I could likely squeak in another 4 ounces, but this is fine for now. I am pretty sure I can keep all up weight under 5 pounds so wing loading will not be a problem.

Beyond this, whatever other silly stuff I can finish in time. As I realized last night, I may return to a project I envisioned years ago and that also should not be a time consuming effort.. see picture attached. The toughest job is crafting the nose pod to hold battery etc., and that is not a big deal. It may not shatter speed records, but it will be funny as heck if nothing else.

MJD

p.s. wake up Mike.. I posted that picture last night.. zzzzz.. oh well, you get the idea.
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