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

Rossi 65 prop...

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Old 11-12-2002, 02:02 AM
  #1  
ChuckAuger
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Default Rossi 65 prop...

OK I tried the 8.8 X9 pylon prop on the 65..it turned up some dang high R's..tach wouldn't pick it up, skiny blades and overcast...I don't know. I was trying to read thru the prop, no way I was standing in front of it. This is the first prop the trusty (?) Futaba tach wouldn't read.

Damn near broke my finger flipping it when it was loaded up a bit. Ouch puts it mildly.

But anyway..the way it would just wrap up instantly, just didn't seem to be absorbing the power like I thought it ought to. So thinking back on some of the post from Dustflyers thread...

I took a 11 X 12 and cut it down to 8.75". Replicated the shape of a 9 X 8, put the undercamber back on the rear face, it looks just like a stock APC except the larger hub (already drilled for 8MM!!) and got the LE and TE sharp just like a stocker. I am real happy with the final result..took an hour to do one prop, but it balances every direction, and I made a masking tape template to be certain the blades are exactly the same shape. Wet sanded with 400 grit to be sure there are no surface cracks..

I wanted to get away from one-off props for a hand launced plane, but there just aren't any props out there.

So I'm going to launch with the prop blades stalled, I think I'll have enough thrust to get off, then try to get it to hit the pipe. I'm using a Rossi 90 pipe with the muffler section turned off, it's actually a fairly small pipe without the muffler and I have about 4" of adjustment (the 90 pipe is larger ID at the neck than the header, so I can adjust without cutting).

When running the 46VRDF, I couldn't get it to run on a Macs 7.5 pipe. Shadel said I had too small volume, that's when the Nelson pipe came into play...and the VRDF ran perfect after that. So I am just going with a 15cc pipe right off.I plan on getting the pipe set for static max, then going about an inch shorter to try to anticipate the unloaded RPMs...it ought to pick up a bunch if I can ever get it on the pipe.

I have in-flight mixture, so hopefully can get it set...I've never tried to lead one this much.

The way I see it, the CL Speed guys go pretty dang fast, run pipes, and have to whip their planes to get them on the pipe. I'm gonna try to do the same thing, I just hope to have enough performance to get altitude to dive and get on the pipe. Whip it so to speak.

So anyway, there is the plan..for better or worse, that's the story.

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Old 11-13-2002, 08:38 AM
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Flyboy Dave
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Default Rossi 65 prop...

.....and then what happened ?
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Old 11-13-2002, 02:14 PM
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Default Nothing...

It's dark by the time I get home, the only shots I have are weekends. Sunday was the first decent day in about a month, we'll see what this weekend brings.
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Old 11-13-2002, 07:00 PM
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Default Rossi 65 prop...

Hey Jeff,

Yeah, be sure to let us know how it goes....Ol' Flyboy can't seem to git any speed outa his Rossi's!

Gary
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Old 11-13-2002, 07:54 PM
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Flyboy Dave
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Default Yo, ChuckAuger....

....there's that Speed-Demon....."AirGar"....let's see
how fast his Jett .90 runs after I wizz in his fuel can.

( Heh Heh Heh ) Dave.
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Old 11-13-2002, 07:59 PM
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Default Rossi 65 prop...

Yo FlyBoy....dem Jetts just LOVE dat "high octane"!

Look out--------> Here comes da AirGar at mach 5!
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Old 11-14-2002, 01:05 AM
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Flyboy Dave
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Default Yo Chuck...

....do ya' think AirGar would notice if I switched
his prop from an 11-8, to an 11-5 ????
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Old 11-14-2002, 01:27 AM
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Default Getting whooped??

Every Rossi I've seen except fans and boats have a very modest 148 degree exhaust duration. Raise it up to 165 or so, and you'll get 1K easy if your pipe is set good. 172 will get you more, it's about as high as I set them for sport flying, but you'll need to start running a little faster prop. And you are a slave to the pipe after you cut 'em, no going back to a muffler. Plus it lowers the compression ratio, and you can run more nitro. It's all good!

And if Gary even lets you near his plane (or fuel jug!) he has not read the "Old age and Treachery" part of your sig! LOL
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Old 11-14-2002, 02:17 AM
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Default Getting whooped??

.....fraid so, Chuck....this guy ( my Bud ) Airgar just
doesn't play fair.

I come out with my .60 F-20, with a .75 in it....He busts
his out with a Jett .90.

I come out with a .40 F-20, with a Rossi .45....He busts
out one with a Jett .50.

I decide on a Viper Q-500 project, with a nice little safe
and sane K&B Q-.40 motor....what does he do ? He sends
off for one of those Kange F3D jobbers. It looks kinda like
a big razor-blade, with a motor mount glued on to the
middle of it . And I heard him mumbling something
about a Jett Q-40 motor the other day.

What am I gonna do with this Dude, he's gonna cost me a
bundle. :stupid:

Signed: Broke at the field....in second place.
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Old 12-25-2002, 09:25 PM
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Default After further investigation..

It would appear I'm running a lot more pitch with this prop. Got a pitch gauge, but no instructions.

If I read the top of the straightedge (you have to be familiar with the Prather Pitch gauge) I get about 15.5" at the tip...about 14.5" at the 8" station. I'm fairly certain you read the top (the pitch is taken off the bottom of the prop blade...), but even on the bottom it's showing 13.5" at the tip.

And I'm just between 15.5K and 16K static...haven't broken 16K yet, but the test stand is buried in snow.

Now if it will just generate enough thrust to launch..
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Old 12-27-2002, 03:53 AM
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Default Rossi 65 prop...

If that was a 11 x 12 and now a 8.75 I have to say you did an awesome job on it. It looks flawless! I would have never know the difference if you not mentioned it.

I cut down and sanded down a few props but never took the time to curve the ends up. How much difference does it make on the performance? I may need to do the same with the ones I have here. Still have a whole bunch of brand new props not touched yet.

One thing though I don't like the balancer I have. I have the magnetic balancer with the 2 cones and shaft. I prepped the magnet as mentioned in directions but it still does not seem as smooth as it should be.
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Old 12-27-2002, 09:51 PM
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Default Cutting props...

I don't know about the difference rounding the tips makes, I was just trying to replicate the shape of the 9X8 sport prop..

I think it is more important to try to get the blade profile back (thickness) and rounding the tips makes for less work in that respect.

After talking to a couple of prop carving pylon racers it would seem that almost every step I took on blade shaping was toward increasing pitch although I didn't know it at the time. Now that I have a pitch gauge, I can see what they were talking about.

That's why the prop that started out as an 11 X 12 ended up with over 15" of pitch. I left the TE shape pretty much alone, but moved the LE back on the blade which increases the pitch, as does re-shaping the back of the blade, like I said, everything I did was a way to increase the pitch. But I didn't know it.

If you think the prop looks good from the front, you should see it on the pitch gauge..I can't believe I nailed it just by eyeball, but it has exactly the same pitch at every station on the gauge. I was amazed when I checked them all.

The Whiplash is now complete, but several inches of snow are still on the field, and the guy who does my chunking is down in his back. I'm ready to try it out.
Here is a pic of it next to a 9X8..as you can see, I didn't exactly match blade shapes, but got as close as I could without getting into the TE shape.

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