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Old Jul 01, 2009, 06:21 PM
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The NOVAROSSI / REX aero engines thread

This thread primarily addresses those R/C speed freaks who intend to use a NOVAROSSI high performance engine for their wicked fast speed plane project.


NOVAROSSI REX aero engines are extremely well built – in fact it is hard to find better built quality. So it's not surprising that NOVAROSSI http://www.novarossi.it/ and their REX and TOP engine lines clearly do represent the number 1 worldwide when it comes to competition, especially in conjunction with .12 to .21 sized engines.

The founder of the Novarossi company is Cesare Rossi, the brother of (in 2005 deceased) Ugo Rossi. In the 1960s the brothers established the ROSSI company (now AXE MOTOR ROSSI http://www.axemotor.it/Axemotor/Cover.html ), but in 1984 Cesare left ROSSI and NOVAROSSI was launched as an independent company.

http://www.novarossi.it/eng/support/distributors/

Check out the factory tour video:
Novarossi Factory (10 min 0 sec)
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Old Jul 01, 2009, 06:28 PM
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The 2.5 to 3.5 cc Novarossi FIRE aero engines totally dominated the F3S-A class (speed planes up to 3.5 cc) during the past years in Germany.

Of course no throttle is used in F3S, only a speed venturi guarantees maximum output.

Fortunately there are commercially available speed props for these .12 to .21 Novarossis , namely the black GRAUPNER Speed Prop series
  • Graupner #1305.15.13,5 SPEED PROP 6.0x5.5”
  • Graupner #1305.16.16 SPEED PROP 6.5x6.5”
  • Graupner #1305.17.17 SPEED PROP 7.0x7.0”
and also the 6.5” diameter APC pylon props
  • LP065050 6.5 x 5”
  • LP065055 6.5 x 5.5”
  • LP065060 6.5 x 6.0”
  • LP065065 6.5 x 6.5“
Do NOT apply the Graupner CAM speed prop series - these are too soft!

Please note:

The above listed Graupner Speed Props feature an 8 mm dia hub bore. For that you have to add an aluminium bushing for proper centering these very well performing speed props to the crankshaft.
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Old Jul 01, 2009, 06:36 PM
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I didn't know Rossi was Russian!

Greg
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Old Jul 01, 2009, 06:44 PM
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Aero engines:

http://www.novarossi.it/eng/products...ane/?brand=rex



The following posts will list those Novarossi/REX engines to use for F3S competition speed flying preferably:



NOVAROSSI REX RFX-15TV
displacement: 2.49 cc
max. power output: 1.80 hp at 35.000 R.P.M.
practical range: 2.000 ~ 40.000 R.P.M.
bore x stroke: 14.69mm x 14.69mm
piston/sleeve construction: true ABC
number of sleeve ports: 5
piston/sleeve assembly: #08252
crankshaft: diameter of 13 mm #15251
crankshaft type: TURBO design for improved gas flow, standard 1/4" x 28 threaded shaft (non-SG type)
carburettor: bore 7mm – speed venturi #20151
glow plug type: Turbo – C5TF (or 6TF or 7TF or 8TF in case of nitro content >10 %)
exhaust position: Rear
fuel: 10% nitro, oil 15 to 20%
weight: 223 gr.



recommended exhaust setup by Novarossi:
#40241 straight (0 degree) exhaust header
#40240 fuse-top style exhaust header
#50240 muffled pipe
alternatively the following MACS products may be used:
# 1110 (un-muffled tuned pipe for maximum performance)
# 1210 (muffled tuned pipe)
recommendations:
  • tuned pipe length: ca. 20 to 22 cm (between glow plug and middle of the pipe's belly or deflector plate respectively)
  • test prop size during break-in at the ground: 4.5x5, 4.5x5.5
  • flight prop for instance: Graupner Speed Prop 6x5.5 shortened to 5” of diameter, APC 6.5x5 pylon shortened to 5” of diameter
  • in-flight rpm: ca 35.000
A typical R/C speed plane design for the RFX-15TV engine is something like below pictured. Only such low drag airframes will enable top speeds exceeding 170 mph with the 2.5 cc Novarossi RFX-15TV.
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Old Jul 01, 2009, 07:04 PM
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NOVAROSSI REX R PLUS 217/FT
displacement: 3.48 cc
max. power output: 2.55 hp at 38.000 R.P.M.
practical range: 2.000 ~ 45.600 R.P.M.
bore x stroke: 16.26mm x 16.80mm
piston/sleeve construction: true ABC
number of sleeve ports: 7
piston/sleeve assembly: #08503
crankshaft: diameter of 14 mm #15054
crankshaft type: TURBO design for improved gas flow, standard 1/4" x 28 threaded shaft (non-SG type)
carburettor: speed venturi with bore of 8 mm is recommended
glow plug type: Turbo – C6TF (or 7TF or 8TF extra cold in case of nitro content >10 %)
exhaust position: Rear
fuel: 10% nitro, oil 15 to 20%
weight: 317 gr.



recommended exhaust setups by Novarossi:
#40041 straight (0 degree) exhaust header
#40040 fuse-top style exhaust header
#50041 muffled pipe
#50040 non-muffled pipe for maximum performance
alternatively the following MACS products may be used:
# 1120 (un-muffled tuned pipe for maximum performance)
# 1220 (muffled tuned pipe)

recommendations:
  • tuned pipe length: ca. 21 to 24 cm (between glow plug and middle of the pipe's belly or deflector plate respectively)
  • test prop size during break-in at the ground: 4.5x5.5, 4.5x6, 5x5
  • flight prop for instance: Graupner Speed Prop 6x5.5 shortened to 5.5” of diameter, Graupner Speed Prop 6.5x6.5 shortened to 5” of diameter, APC 6.5x5 pylon
  • in-flight rpm: ca 35.000

A typical R/C speed plane design for the R PLUS 217/FT engine is something like below pictured. Only such low drag airframes will enable top speeds exceeding 180 mph with the 3.5 cc Novarossi R PLUS 217/FT.
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Old Jul 01, 2009, 07:11 PM
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NOVAROSSI REX R61F
displacement: 9.98 cc
max. power output: 2.45 hp at 17.000 R.P.M.
practical range: 2.000 ~ 20.400 R.P.M.
bore x stroke: 23 mm x 24 mm
piston/sleeve construction: true ABC
number of sleeve ports: 4
piston/sleeve assembly: #08420
crankshaft: diameter of 18 mm + bore of 11.5 mm # 15400
crankshaft type: TURBO design for improved gas flow, standard M8 threaded shaft
carburettor: speed venturi with bore of 11 mm is recommended
glow plug type: Standard - C6S (or C7, C8, ROSSI R8 extra cold or McCoy MC9 in case of nitro content >10 %)
exhaust position: Rear
fuel: 10% nitro, 20% of oil
weight: 620 gr.



exhaust headers by Novarossi:
#40400 straight (0 degree) exhaust header
#40401 fuse-top style exhaust header
one of the following tuned pipes should be used (because the .60 sized muffled tuned pipes by Novarossi are too restrictive for all-out speed ):
MACS # 1160 (un-muffled tuned pipe)
MACS # 1260 (muffled tuned pipe)
OPS # 6280 non-muffled tuned pipe
OPS # 6780 muffled tuned pipe
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Old Jul 01, 2009, 07:20 PM
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The next picture shows the NOVAROSSI REX R61H “heli” engine disassembled.

Take a look at the excellent craftsmanship and design details:




The main internal difference between the NOVAROSSI REX R61F “aero” and the R61H “heli” engine is the sleeve ports design. While the aero engine does feature a 4-ports layout (two booster ports and two transfers) the helicopter engine comes with a 6-ports sleeve (two booster ports and four transfers, below pictured). Fortunately the helicopter piston/sleeve assembly #08405 is a direct replacement for the “aero” engine , just in case you prefer the 6-ports liner.




This is the stock (non-modified) crankshaft of the NOVAROSSI REX R61F and the R61H featuring “turbo” cuts that do improve gas flow:




Some stock (non-modified) NOVAROSSI REX R61F engines disassembled. The stock ball bearings already come as C3 low friction types with phenolic retainers:
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Old Jul 01, 2009, 07:25 PM
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Old Jul 01, 2009, 07:41 PM
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Sadly the stock timing numbers of the NOVAROSSI REX R61F and R61H heli engine are very conservative in terms of speed application:
exhaust duration: 150 degrees (at least 180 is desirable)
transfers: 118 degrees (about 130 is desirable)
boosters: 118 degrees (about 130 is desirable)
crank intake:
opening after BDC: 38 degrees (at least 30 is desirable for better volumetric efficiency)
closing after TDC: 57 degrees (at least 60 is desirable for better volumetric efficiency)
These stock timing numbers clearly show that the 10 cc Novarossi FIRE engines originally have been torque-optimised for pattern and heli applications.

However, to obtain a true NOVAROSSI 10 cc speed engine that is able to compete with the established OPS .60 super SPP VAE engine for instance, many essential internal alterations have to be carried out:

improving gas flow at the sleeve's transfers and boosters:




increasing the sleeve's exhaust duration:




adapting the exhaust port of the aluminium housing to the new liner's exhaust port height:




adding lubricating holes to the stock knife-edge shaped connecting rod +
milling two additional by-passes into the liner (below the transfers) +
making a piston from special 30% SI-aluminium material
milling additional by-passes into the piston side skirt (matching the new sleeve's lubricating by-passes when the piston is at BDC) +
lighten the piston by reducing skirt wall thickness +
increasing the crankshaft bore +
fine-tune the “turbo-styled” crankshaft design +
increasing the crankshaft intake timing duration:




milling a completely new designed (“turboed”) back plate:




These highly modified Novarossi 10 cc FIRE engines also feature a speed venturi carburettor and a custom made head button accepting heavy duty “Turbo” or “Nelson” glow plugs. They now perform very similar, if not better than a stock OPS .60 super SPP VAE – both are FAI legal (they stay below 10 cc) and thus are suitable to set a new F3S-C world speed record.

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Old Jul 01, 2009, 08:00 PM
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Recommendations for highly customised NOVAROSSI REX R61F or R61H engines:
  • tuned pipe length: ca. 26 to 28 cm (between glow plug and middle of the pipe's belly or deflector plate respectively)
  • test prop size during break-in: home-made carbon fiber copy of the APC 8.75x9W pylon or APC 8.75x9.5NN pylon shortened to 8” of diameter
  • flight prop for instance: home-made carbon fiber copy of the APC 8.75x9W pylon or APC 8.75x9.5NN pylon or APC 8.8x9.75 pylon
  • in-flight rpm: ca 24.000
A typical R/C speed plane design for the R61 engine is something like below pictured. Only such low drag airframes will enable top speeds exceeding 210 mph using the highly modified NOVAROSSI REX R61F or R61H.



So if you are a true engine nut who has access to the required tooling/machining equipment, then purchasing and modifying the NOVAROSSI REX R61F or R61H engine is recommended.
If not, the bone-stock gold-head OPS .60 super SPP VAE engine is the way to go 220 mph + (please go to The OPS engine thread for more info).
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Old Jul 01, 2009, 09:24 PM
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I have some Rossi Bi-Turbo plugs. These have a different taper on the nose than the regular turbo plug. What were these used for?

I also have some of the aluminum bodied standard glow plugs. I don't think these were made for very long.

I have a couple 90's Rossi catalogs I could be persuaded to scan and post.

The stuff being done by the F3S Speed Cup guys is pretty cool.

Greg
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Old Jul 02, 2009, 04:00 PM
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Well I only know the regular style ”turbo“ plugs used for most speed applications below 5 cc (on-road, off-road, marine, aero-speed, tether car).

Maybe you want to post a picture here showing both ”turbo“ plug cone shapes side by side in detail?


Generally cone-type plugs should always be favoured over a 1/4-32 standard glow plug, because such ”turbo” plugs (including Nelson and GloBee plugs)
  • only little disrupt the combustion chamber shape ( > higher top rpm achievable)
  • seal better
  • provide smoother throttle characteristics
  • potentially last longer

As for the catalogs I think many performance IC engine enthusiasts here at RCgroups (me included) would be glad to find a PDF-file of each of your rare catalog added to this thread– be it a Rossi or a Novarossi...
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Old Jul 02, 2009, 04:27 PM
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No time today, but after the weekend I'll post some stuff.

Greg
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Old Jul 04, 2009, 01:41 PM
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In reference to post #9 the liner's stock timing numbers of the NOVAROSSI REX R61F and R61H engine by no means are suitable for F3S speed flying.


There are different approaches to increase the duration of the booster ports, of the transfer ports and of the exhaust port:


The more time-consuming (and more expensive) approach already has been covered in post #9, i.e. adjusting the top edge of each port upwards. It is of vital importance to maintain the original port window angles during milling!

People sometimes do raise the exhaust port only (boosters and transfers remain stock). In case of the stock 150 degrees exhaust time of the R61 Novarossi engines that means an extreme change of 30 degrees to achieve the suggested 180.
But raising the exhaust port always is connected to a loss of cylinder compression. So after adding 30 degrees of exhaust duration applying a very thin head shim plus using higher % nitro fuel will be necessary to keep the compression ratio near stock. Sometimes even a new head button is required that features a different combustion chamber shape (smaller bowl volume).

Raising the exhaust but maintaining the stock booster and transfer timing is not favourable in case of the Novarossi R61 FIRE if top end performance is desired. The difference between 118 degrees of boosters/transfers and 180 degrees of exhaust will lead to unwanted scavenging losses at the desired rpm well above 20.000. Therefore also the timing numbers of the booster and the transfer ports of the R61 engine should be changed (128 to 130 degrees will be fine).

To get the booster and transfer timing numbers right in a quite simple manner (thus less expensive) sometimes a cylinder sleeve shim (liner shim) is applied. That shim is placed directly below the liner lip and should be made of steel or brass. The bottom of each port of a shimmed liner is to be kept stock (no machining down to the original lower edge port position is required).

But there are two disadvantages associated with the application of a sleeve shim:
  • Firstly when raising the entire liner of an ABC or AAC engine the tapered piston/sleeve fit will turn out to be less tight. So a sleeve shim should be applied in combination with a new never used ABC or AAC piston/sleeve assembly preferably.
  • Secondly the compression ratio in connection with a shimmed liner may be too small for excellent performance - depending on the shim thickness. To get the compression right we just have to trim the top side of the liner lip on a lathe. For instance if a 1 mm thick sleeve shim is applied then the lip thickness has to be reduced by 1 mm...


example of using a liner shim (see also pics below attached):
Our NOVAROSSI REX R61 engine comes with a stock liner lip thickness of 3.00 mm.
To raise the booster and transfer timing from 118 degrees to the desired 129 degrees by a liner shim that shim has to be 1.25 mm thick.
So we have to reduce the liner lip thickness to 1.75 mm to normalize compression.
In this case we shouldn't use a thicker shim than 1.25 mm for the R61 engine because 1.75 mm of liner lip thickness already is quite thin for a 10 cc high performance engine).
The exhaust timing of our shimmed liner now is 163 degrees instead of stock 150. Because we want at least 180 degrees of duration the exhaust port has to be raised adequately by milling.


Of course whenever the top edge of a liner port is shifted upwards (by a sleeve shim or by milling), also the aluminium cylinder housing gas passages have to be matched by milling to the new liner's port heights...
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Old Jul 05, 2009, 09:41 AM
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Novarossi have just revised their homepage. Apparently they now offer the “SPEED” version of the standard FIRE R61F pattern engine officially:

http://www.novarossi.it/eng/products...PEED&brand=rex


NOVAROSSI REX R61F SPEED
displacement: 9.98 cc
max. power output: 2.45 hp at 17.000 R.P.M.
practical range: 2.000 ~ 20.400 R.P.M.
bore x stroke: 23 mm x 24 mm
piston/sleeve construction: true ABC
number of sleeve ports: 4
piston/sleeve assembly: #08421
crankshaft: diameter of 18 mm # 15402
crankshaft type: TURBO design for improved gas flow, standard M8 threaded shaft
carburettor: speed venturi with bore of 9 mm #20155
glow plug type: Standard - C6S (or C7, C8, ROSSI R8 extra cold or McCoy MC9 in case of nitro content >10 %)
exhaust position: Rear
fuel: 10% nitro, 20% of oil
weight: 620 gr.


exhaust headers by Novarossi:
#40400 straight (0 degree) exhaust header
#40401 fuse-top style exhaust header
one of the following tuned pipes should be used (because the .60 sized muffled tuned pipes by Novarossi are too restrictive for all-out speed ):
MACS # 1160 (un-muffled tuned pipe)
MACS # 1260 (muffled tuned pipe)
OPS # 6280 non-muffled tuned pipe
OPS # 6780 muffled tuned pipe

recommendations:
  • tuned pipe length: ca. 26 to 28 cm (between glow plug and middle of the pipe's belly or deflector plate respectively)
  • target rpm should be about 24.000 unloaded
  • test prop size during break-in: home-made carbon fiber copy of the APC 8.75x9W pylon or APC 8.75x9.5NN pylon shortened to 8” of diameter
  • flight prop for instance: home-made carbon fiber copy of the APC 8.75x9W pylon or APC 8.75x9.5NN pylon or APC 8.8x9.75 pylon

This Novarossi R61F SPEED comes with the mandatory speed venturi carb. But the venturi bore of only 9 mm is a little narrow for a 10 cc speed engine to be honest.

Obviously the R61F SPEED features a modified ABC piston/sleeve assembly and a modified crankshaft since the spare part numbers are different to the R61F pattern engine.

So let's hope that not only the exhaust but also the booster and transfer port timings have been raised appropriately. Hopefully the crankshaft intake timings have been optimised as well.

So it would be fine for the speed freaks to see an engine review of this Novarossi R61F factory SPEED edition added to this thread in future. The timing numbers characterising this factory tuned speed engine - being fully FAI compliant – already will tell us lots about its potential for setting F3S speed records. Maybe it will be able to beat even the OPS .60 super SPP VAE engine...
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