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

motor for speed in a small plane

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Old 11-16-2006, 12:24 AM
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Julian537
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Default motor for speed in a small plane

Has any one used one of these motors? Navarossi .21
[link=http://www.planethobby.com/product.php?productid=497&cat=3&page=1].21 side exhaust[/link]
Seems to produce some very high RPM. Might be a good motor for an Outlaw, sig wonder, or something small like that?


They also have a rear exhaust version that will do 34,000 RPM

[link=http://www.planethobby.com/product.php?productid=521&cat=3&page=1]21 rear exhaust[/link]
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Old 11-16-2006, 09:28 AM
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Default RE: motor for speed in a small plane


ORIGINAL: Julian537

Has any one used one of these motors? Navarossi .21
[link=http://www.planethobby.com/product.php?productid=497&cat=3&page=1].21 side exhaust[/link]
Seems to produce some very high RPM. Might be a good motor for an Outlaw, sig wonder, or something small like that?


They also have a rear exhaust version that will do 34,000 RPM

[link=http://www.planethobby.com/product.php?productid=521&cat=3&page=1]21 rear exhaust[/link]
First, the NovaRossi .21 is indeed a real good engine. Well built, and powerful.

from the website there....
Power: 2.2 H.P. at 34,300 RPM

ok, perhaps when used in a car with gearing and no torque requirements
(they should not copy the road engine data into the aero engine information - the engines are different)

Put a useable 8x6 prop or similar on it. Then get let me know if it gets anything substantially over 19,000-20,000 rpm. Respectable - but reasonable.

(published HP and rpm are generally meaningless numbers, unless somehow estabilished and compaired using standard methods, and then tied back to the real-world usage)

Anyway... for any of those aircraft you noted, yes...... it would be a fun choice. Definately will give you some significant performance.
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Old 11-16-2006, 01:09 PM
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Default RE: motor for speed in a small plane

Julian 537:

My favorite engine of all time (lots of time) is the Jett BSE 35. Mine has been racing the 46 and above engines in a local club anything goes class now ending its third sseason, and saving wall space for another year of first's overall for the third year in a row. Little guy just keeps getting stonger, gives me 18-20K with a 8.5 X 7.5 or 8 apc pylon prop. If I over lean it while on the bench, it comes right back, stays running when a little lean with no damage, a generally overall tough and user friendly. Gotta beat it with a stick to stop it ideling!!! Yes, a little expensive for the first year of purchase, now its a great cheep engine. Other guys are working on their third engine while mine just keeps on performing stonger. I suspect it may outlive me!
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Old 11-16-2006, 02:00 PM
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Default RE: motor for speed in a small plane

In Holland some people are using this engine for Club 20 pylonracing. With a 7x6 APC and Irvine Magic Muffler we're getting about 20 KRpm on 5% nitro.
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Old 11-16-2006, 03:25 PM
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Default RE: motor for speed in a small plane

Most engines will spin really fast if they have very little load on them, at least as far as their porting/intake setup allows. However their life span may be mercilessly short if not built for it. Don't be fooled by unqualified rpm claims - that type of marketing hype is aimed at the car crowd. Without telling you what load it will spin to those rpm's, the information is useless. My .010's will spin that fast too - if you clip down the 3" prop a bit.

The size of prop you'd need to fly to let the NR engine unload to those rpm on an aircraft would be limited in use to light and aerodynamically extremely clean airframes. Better to use more displacement, run a prop with useful disc area, and enjoy the tractability that comes with a less highly strung engine. Plus, you are not saving any weight with the NovaRossi .21 over larger engines. It is not a lightweight - generally car engines don't need to be as light as aircraft engines but do need to suffer a lot more abuse.

I found one set of specs on a Novarossi .21 that says it weighs 330 grams, aka 11.6 ounces. That's without pipe. Hmm. The entire Jett FIRE .30 case-size lineup (.25-.40) weighs in at less than this, and also cost less than the NovaRossi's I was able to find on the 'net. Consider the FIRE BSE .35 ABC for example - it will turn a 9-6 at about 18,500 (compare that to 20k on a 7-6!), it idles and throttles beautifully, and weighs 11.5 ounces less pipe. The FISE version costs $295.00 and weighs 14.3 ounces with the supplied muffler.

I think you would get a lot more motor for these applications looking elsewhere, for example at a Jett .35.

MJD


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Old 11-16-2006, 04:06 PM
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Default RE: motor for speed in a small plane

Without telling you what load it will spin to those rpm's, the information is useless.
They are telling you what kind of load it will spin at 34K.
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Old 11-16-2006, 05:09 PM
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Default RE: motor for speed in a small plane

ORIGINAL: HighPlains

Without telling you what load it will spin to those rpm's, the information is useless.
They are telling you what kind of load it will spin at 34K.
Where do they say that? In the places I looked at, I saw comments like "revs up to 34k". I didn't see "produces ___ torque at 34K". Maybe I looked at the wrong places? I don't buy much into horsepower claims, although one could back out torque from claimed hosepower I suppose, to arrive at "claimed torque".
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Old 11-16-2006, 08:29 PM
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Default RE: motor for speed in a small plane

Hello, the German speed guys do use such converted .21 car engines for their speedmodells to compete in the annual speed-cup. Appropriate prop sizes are about 5.5 x 6 to get 28000 to 30000 U/min on the ground. So 34000 in flight are quite realistic! But MJD already has pointed out that only special low drag speed airframes (see pic) will handle that small prop diameters.
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Old 11-17-2006, 02:45 PM
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Default RE: motor for speed in a small plane

I have the Nova Rossi .21 rear exhaust and tuned pipe on a Diamond Dust. I use an APC 7x6 cut down to 5.45 inches and get 28,000 on the ground. The plane has been flown with a Webra .40 side exhaust and a K&B 6.5 rear exhaust with tuned pipe but the Nova Rossi is much faster. The launch with this engine is fairly slow but when the plane gets to top speed it is almost as fast as my Diamond Dust with the Jett Fire 60LX. I have also cut down the APC 7x8 and 7x9 propellers with good results, I just keep cutting the propeller until I get 28,000 rpm. The fastest combination was with 25% nitro fuel and a cut down 7x8 propeller. I recommend this engine for a small plane but it is fairly heavy for it's displacement but not for it's power. I may remove this engine from my DD and install it in a Prather Little Toni quarter scale racer. I believe that this would be faster than the Diamond Dust.
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