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 53 questions

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Old 08-02-2006, 09:12 PM
  #1  
flyinrazrback
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Default Rossi 53 questions

Just bought a Rossi 53 and the nelson pylon muffler for it. What is a good prop to start with, its going on the front of a lanier predator, I was thinking 8.75x8 to start with. What fuel, and plugs work best? What is a safe rpm that this motor can turn up to?
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Old 08-03-2006, 08:41 AM
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Default RE: Rossi 53 questions

The engine likes rpm ..... dont worry about turning it too fast.

the 8.75x8 is ok to start with. Also try a 8.8x8.5

With the ultrathrust/nelson muffler, you want to prop the engine to turn at least 16,000 rpm. Perferably a bit higher.

K&B 1-L, Rossi 3 or 4, OS8, McCoy59 plugs are good choices

Fuel..... less is better, stick with regular 10% sport fuel, 15% is ok. FAI 0% or 5% is great too.
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Old 08-22-2006, 08:44 PM
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Julian537
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Default RE: Rossi 53 questions

I have this engine now and I am running an 8.8X8.75 and it is not as fast as I expected. I am flying it up against my rookie 25. The rookie 25 is running a OS .32 and a 9x7 prop. It is spinning the 9x7 at 15000 RPM. It pulls away from my predator with the rossi .53 and 8.8X8.75 prop. the rossi is turning that prop at 17,000 with the jett muffler.

Does any one have any suggestions for proping this Rossi .53?
I am thinking it needs more pitch to load it up a bit.
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Old 08-22-2006, 08:56 PM
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Julian537
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Default RE: Rossi 53 questions

What are the W pylon props from APC and what are the NN props ?
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Old 08-22-2006, 11:49 PM
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Default RE: Rossi 53 questions

Those are the props that Jett recommended to me. An APC 8x9W my work. The APC W props are wide, and the NN are the narrow blades.
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Old 08-23-2006, 01:03 AM
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Default RE: Rossi 53 questions

Julian, it sounds like that Rossi just can't unload as far as that little OS can . That's the same thing that I had with a Webra 55 with a red jett muffler . The only propeller it really likes is a 9x10 APC ( a good thing) and turns it better than 16,000 RPM on the ground. Now my diamond dust really screams when it unloads. I would try some of the following on the Rossi, 9x10 (Humor me) , 9x9, 8.75x9.5 and a 8x10 APC. Kinda weird but I've had good luck with standard short Fox glow plugs on the webra about 15 seven minute flights per plug VS 3 with OS #8s. I set my high speed needle 1000 rpm down from peak (rich), it will lean as it unloads in the air. Standard, foam supported 8 oz no bladder tank.
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Old 08-23-2006, 10:14 AM
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Default RE: Rossi 53 questions

Sounds like your Rossi is hitting the right rpm range....... it should be going like heck with that prop. Unless it is just not unloading in the air very well.

Try a 8.8x8.5 or if you can find one a 8.75x8.25 prop. Those will let the engine unload more (if it wants to - might be limited). Then try the 8.75x9W

Also, try that same 9x7 apc your buddy is running (will turn up well).
Say away from the NN props for speed. They are not real fast, but they are good for in-flight engine breakin.

Your key in prop selection is rpm. Set the engine to turn between 16,000 and 17,000 round peak rpm. Select props that do that. Find peak, back off the mixture about 500-600 rpm - and fly it.

Just of note, a Thunder Tiger .40 pro, 15% fuel, with an APC 9x6, set up for 424 racing (stock, properly broken in), will turn 16,300-16,500 peak on the ground with an apc C-2 9x6. A preditor with that setup will fly about 120 in extended level flight, and about 100mph on the race course.

Your Pred with the Rossi 53, turning the prop you noted at rpm noted should hit closer to 130+ in level flight.

Same engine will turn just above 15,500 with an unmodified apc C-2 9x7. If your buddy has a stock muffler and stuff on that OS32, he has one hell of a good engine

Bob
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Old 08-23-2006, 02:39 PM
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Default RE: Rossi 53 questions

Bob and FF
What do you mean by the "Prop unloading" in the air?
This motor screams with the 8.8x8.75 on the ground. It does not sound like it is screaming though when it flies by.
It does not sound like it is hitting the same RPM in the air.
Does this mean it has to much prop on it?


BTW my rookie has the OS .32 with a mousse can pipe on it. And it spins that 9x7 prop pretty well.
Maybe my rookie is just that fast???? it is a smaller plane? I dought it though!
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Old 08-23-2006, 03:09 PM
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Default RE: Rossi 53 questions

the static load on a prop/engine on the ground is one measurable way of seeing how an engine is running. However, when actually moving through the air, most props will be more efficient, and the forward velocity component reduces the load on the engine - resulting in higher engine rpm in the air. Also, the jett muffler will enhance this effect - its range runs from about 16K to 18K rpm in flight. So if an engine is turning a decent prop at 17K on the ground, it will most certainly unload an additional 500 or more in the air.

If your engine is not doing this - check your fuel system. If that is not the problem, the engine timing/porting may be reaching its limits - you are already taking off at peak rpm, thus the engine does not unload much further - in which case, prop down to about 16K rpm static ground peak rpm - more prop - then it has room to go those extra few rpm.

At those rpm/power levels - it is wise to use a tetra or jett bubble-free fuel tank. Often enough, especially in a Q-500 airframe, you will get foam in the fuel - which will cause the engine to go over-lean in the air.

The OS32 does respond great to a tuned exhaust or moouse can. Pretty amazing little engine.
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Old 08-23-2006, 08:53 PM
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Default RE: Rossi 53 questions

Bob,

I am running the jett bubbless tank on this plane. It is getting great fuel flow from this tank.
I will try to prop it up a bit so it can unload in the air.
thank you for all of your help!
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Old 08-23-2006, 11:06 PM
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Default RE: Rossi 53 questions

Julian, your engine is rated a healthy 2.3 hp @ 16,000 and has 22.22 mm stroke (fairly long). Even thou it has 5 ports(associated with high rpm)I think it has a torque monster port timing and it makes it’s power at a somewhat lower rpm like my Webra and it wants a steep pitch prop(see my earlier post) to get air speed. 15,500/ 16,500 rpm on the ground could max out in the air to say 20,000 with the right pipe/muffler. Look at the suggested operating ranges for the 5 different Rossi 53 muffler/pipe combos; http://shop.vendio.com/RossiEnginesUSA/category/1/
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Old 08-23-2006, 11:48 PM
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Default RE: Rossi 53 questions

Ok FF

I am going to prop it up some. Get it down to 15,500 or so on the ground and see what it does in the air.
All of this is making sense to me now. It is great to have all this knowledge here for help.

This sounds like what I did with the OS .32. It would scream like a banchee with a 9*5 prop but did not go anywhere. I put it up against my wonder with a .25 and a tuned pipe. the .25 OS has a 8.5*7.5 prop on it an it would pull away from the .32.
I put the 9x7 on the .32 and it now pulls away from the .25. It does not scream on the ground like it did before, but you can hear it unload in the air. (it wraps up higher)

It all just clicked.

Thank you everyone. I will let you all know how it does.
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Old 09-04-2006, 11:22 PM
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Default RE: Rossi 53 questions

Ok,
Got the new props and flew it on Sunday. The 9x10sport loaded it up to much. took the RPM's down to 13,000 range.
tried a 8.8X 9.5nn pylon and it did not load it down at all.
also tried a 9x9sport and it seamed to work well. Tuned the 9x9 on the ground, but it seamed to unload in the air.
I need some advice here???
the 9x9sport was tuned up on the ground and I flew it around on half throttle waiting for my buddy to get the rookie in the air.
we raced and I was pulling away from the rookie. Then it fell flat on its face.

Do I need to tune it rich on the ground? so when it unloads in the air that it does not go lean?
seemed to run great for a bit after running part throttle, then it hit a wall?
what about a 10" prop? I have not found any good 10" props that are race worthy. they are all sport props?
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Old 09-05-2006, 09:27 AM
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Default RE: Rossi 53 questions


ORIGINAL: Julian537


Do I need to tune it rich on the ground? so when it unloads in the air that it does not go lean?
seemed to run great for a bit after running part throttle, then it hit a wall?
what about a 10" prop? I have not found any good 10" props that are race worthy. they are all sport props?
Exactly. When the engine unloads, it needs more fuel.

You want to launch about 600 rpm down from peak rpm (on average).

An engine going flat like that generally means it got hot.

The prop you would want to try is the 8.75x9W ..... the NN props are only good for break-in. No blade area.
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Old 09-05-2006, 09:52 AM
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Default RE: Rossi 53 questions

Bob,

thank you.

I have one of the 8.75 x 9W props. I will try that on the plane and see how it does. I will see how much it will load it down on the ground.

Maybe this has been my problem this whole time? I am leaning the motor out too much on the ground??
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Old 09-12-2006, 07:38 PM
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Default RE: Rossi 53 questions

I tried the 8.75x9 prop over this weekend. It would spin 17,000 on the ground.
How much should I richen it up before takeoff?
I richened it up about 1000 RPM before the flight, but it still leaned out and hit a wall. Came down and checked the plug and it was all twisted up. This leads me to beleive it went lean again.
If I lean the motor up more it drops some signifigant RPM. it drops to about 13,900. Makes it a bit tough to take off.

Any thoughts?
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Old 09-12-2006, 08:49 PM
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Default RE: Rossi 53 questions

Julian537, You might try checking the rpm with say a 9-8 with the tuned muffler removed. Then install the tuned muffler and check the rpm again. See if you are getting a net gain or loss in rpm. It sounds like the engine does not have the correct exhaust timing needed for the short ultrathrust muffler.
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Old 09-13-2006, 08:05 AM
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Default RE: Rossi 53 questions


ORIGINAL: Julian537

.... I richened it up about 1000 RPM before the flight, but it still leaned out and hit a wall. Came down and checked the plug and it was all twisted up. .....
Be sure you are getting 100% of the air out of the bubble-jett tank. Going lean in the air and blowing a plug like that indicates fuel foam, a restriction, or an air leak somewhere.

Usually backing down from peak 600-700 is pleanty. If you find 1000 isnt cutting it.. try a bit more. If it is clearly over-rich at launch and still goes lean, start looking for kinks in the tubes or a leaking carb/carb body.

If you get the engine hot (drops from 16000 to 13,000 like you said) there is no way you can set the needle properly - it will not recover by making it rich again. Engine has to completely cool, then try again.

Although the 17K sounds ok, and you are launching at 16,000 apparently which is right on target - but if the engine is just not being 'happy' - you have to work with props suited to the engine/tuned muffler.

Bob
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Old 09-13-2006, 08:59 PM
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Default RE: Rossi 53 questions

Correction in my last post. It should have read, if I richen it up more it drops some significant RPM.
Not lean.
It will try again this weekend.
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Old 09-14-2006, 09:31 PM
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Default RE: Rossi 53 questions

One thing some here may haven't thought of is the low speed needle. The low speed needle needs to be on the rich side along with the high needle. If the low needle is set to idle well it will restrict the fuel flow when the engine come up on the pipe and the rpms increase drasticaly there by giving you a lean run that will go flat, as you say. A pipe requires a lot of fuel delivery or you have problems. If you can richen it up by 1000 though you mush have some fuel delivery on the ground, could be different in the air though. If I were you I would open the low speed needle a bout 1/2 turn and see what it does.
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Old 09-14-2006, 09:32 PM
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Default RE: Rossi 53 questions

Thanks Buzz, great Idea!
I will try this on the next flight
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Old 06-03-2007, 05:30 PM
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Default RE: Rossi 53 questions

What is the RPM limit of this motor?
I called Dub Jett on Friday about this... This motor actually has the black pylon race Jett muffler on it. and I think this is the issue. This motor does not have enough exhaust timing to really get on this short pipe. I can put a smaller prop on it.
Dub sugested using a smaller prop until I got the motor in the RPM range and could richen it up 1k and it did not fall off of the pipe. but the motor cannot breath well with the low port timing. I am thinking that this motor needs a sport muffler to work right??
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Old 06-03-2007, 06:05 PM
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Default RE: Rossi 53 questions

i got a rossi 53 with a UT pylon muffler. running 5% nitro and a 8.8x8.75 prop. hauls the Sonic 500 like a mad beast. im not sure how fast it goes. the guys at the field were guessing roughly 150-160 mph. im a poor judge at speed guesses. i just know it moves like its tail is on fire lol.
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Old 06-03-2007, 08:13 PM
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Default RE: Rossi 53 questions

BBJ,

What is the total length of that pipe, from end to end. The Jett pylon exhaust is only 6.5 inches long. from stinger to front end.
It will get on the pipe, but if I try to richen it up, it falls off the pipe.
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Old 06-03-2007, 08:26 PM
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Default RE: Rossi 53 questions

but will it get back on the pipe once in the air?
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