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Frequently Asked Questions
 

RCV Engines General

Power
Fuel
Engine Configuration 
Engine Developments
Engine Wear

RCV CD Series

Power          What are the CD series equivalent in power to?
What are the approximate fuel consumption figures for the engines?
Props What size props are recommended?
Engine Configuration Can I run the engine inverted?
Can I rotate the carb 180 degrees?
Mounting What kind of engine bearer would I need?
Troubleshooting Oil is leaking from the crankcase breather
Oil is leaking from the front bearing

RCV SP Series Engines

Power          What are the SP engines equivalent in power to?
What model weight / wingspan would suit the engines?
What is the approximate fuel consumption figures?
Running In What is suitable test bench for running in SPengines?
Noise What is a typical noise reading?
Cooling / Fins Would  it be beneficial to cast the cooling fins in the opposite direction?
What would happen if the engine wasn't cooled properly?
If the engine is tightly cowled do you have any suggestions to improve cooling?
Props & Spinners What size props are recommended?
Can wooden props be used?
Where can I obtain spinners for my RCV?
Starting Can these engines be started from the front by spinning the prop?   Or only from the starter socket?
How does the starting adapter fit onto my starter motor?
How does the 'behind the prop' starting work?
Engine Configuration  Would it cause any running problems if I rotated the engine but didn't keep the glow plug at the top?
Mounting How should the engine be mounted?
Troubleshooting Troubles with starting

Tips & Hints

Further tips and hints can be found on our top tips page

 

RCV Engines General

Are the engines 2 or 4 cycle?
RCV make 4-cycle (4-stroke) engines.  The rotating cylinder is effectively combined with the rotary valve in a single component and this simple arrangement of the valve serves the combustion chamber as the engine cycles through the conventional 4-cycles: induction, compression; power and exhaust.

What fuel is recommended for use in the engines?
Methanol Based.  Due to the configuration of our engines, the engines do prefer a fuel that has 10% Nitro / 15% Oil (inc. a max of 6% Castor).  In the UK we use Model Technics Duraglo 10.  The RCV is a little more sensitive than many other engines to fuel and plug selection (OS'F' type recommended) so it is essential this is followed.

Can the RCV engines be used in a pusher configuration?
All the RCV engines should be fine with regard to power and the reverse thrust will not affect the bearings in any way. 
For cooling the SP series engines, you would need to ensure plenty of ducting to force air around the engine.  RCV have not tested a pusher configuration to date, however a number of RCV users have intended their engine to be used in a pusher configuration.   Whatever rule applies to a conventional engine applies to the RCV.  With the SP series engine, it may be more difficult getting the scale size pusher propellers that they would require.  Currently Bolly and Zinger have some propellers which should be suitable for SP pusher applications. 

Is it possible to reverse the rotation of the engine?
Unfortunately clockwise rotation is currently not possible on the engine without extensive engineering changes.

I need a different angled exhaust pipe?
RCV only make the standard exhaust pipe provided with your engine.  The pipe threads however are standard sizes therefore you can pick up a pipe suitable for another 4-stroke engine (eg. OS) and it will fit.  The thread sizes are as follows:
M10 x 0.75   -   RCV60SP
M11 x 0.75   -   RCV58-CD ; RCV91-CD ; RCV90-SP ; RCV120-SP

Do you plan to develop a marine or a car version?
There are no plans for a marine RCV at the present. However we believe it does offer some major advantages for marine applications. In particular the low profile, the starting method of the SP series (which would enable you to start the engine from above the boat via the crank coupling), the 2:1 gearing which enables a lower prop speed, and the mounting method which makes shaft alignment easier.
With regard to car versions - we currently have a customer who is trying to convert a 58CD for use in r/c cars.   Once we have feedback on this, we will update the website, however it is unlikely that we will be developing this further as yet.

What is the next engine you plan to develop?
We are currently looking at another CD engine, and will update the website once a release date has been confirmed. Watch this space...

Are the gears liable to wear out?
The answer to that is no.  In terms of gear longevity, RCV do a standard 50 hour test on the engines and we haven't experienced any significant wear problems on any of the components.  The gears are flame hardened to increase their strength.

RCV58-CD

What are the CD series equivalent in power to?
The RCV engines are equivalent to any other conventional 4-stroke in terms of power.   To relate this to a 2-stroke design the RCV58-CD is equivalent to a 40 2-stroke, the 91CD is equivalent to a 60 2-stroke.  All RCV engines get more powerful the more they are run.

What are the approximate fuel consumption figures for the engines?

RCV58-CD Engine
Method - Record time taken to consume 50ml fuel at various engine speeds
Load - 12 x 6 Graupner Propeller

RPM TIME TAKEN (secs) ml/min oz/min
3000 580 5.17 0.18
5000 500 6.00 0.21
7000 390 7.69 0.27
9000 250 12.00 0.42

RCV91-CD Engine
These are to be updated shortly

What size propellers are recommended & what rpm can I expect?
The CD engines use conventional sized propellers. 
RCV Engines are able to supply propellers suitable for use with our engines for more information of the range of propellers available please

Can I run my engine inverted?
Yes.  We have tested the engine both flying and mounted in an inverted position and the engine performs well. We do however recommend following our fuel recommendations and ensuring a high quality fuel is used.
During the run-in process we would however recommend mounting the engine upright.

Can I rotate the carb 180 degrees?
Yes.  Some of our users find this position suits their application.

What kind of engine bearer would I need?
As the RCV58-CD is slightly wider than some of the more conventional engines (although much shorter in height) a flexible engine bearer is ideal for mounting.  The same mount can be used for our RCV91-CD engine.

Oil is leaking from the crankcase breather?
This is perfectly normal during the run-in period.  Once the engine has been run for approximately 1 hour you will notice this is reducing and will continue reducing as the engine beds in.

Oil is leaking from the front bearing?
During the intial run-in period (approx 1 hour) some green grease may be seen seeping from the front bearing.  This is nothing to worry about as the engine bearing is pre-packed with the green grease and will decrease as the engine beds in. 

RCV SP Series

What is the RCV equivalent in power to?
The RCV engines are equivalent to any other conventional 4-stroke in terms of power.  To relate this to a 2-stroke design the 60SP is equivalent to a 40 2-stroke, the 90SP is equivalent to a 60 2-stroke and the 120SP is equivalent to a 90 2-stroke.

What model weight  would suit the engines?
This really depends on the model it is used in. i.e whether it is fast or slow running model and we generally believe the kits give the best sort of guideline.  As a rough estimate, the following can be applied (weights can be more or less depending on the plane & type of flying):

Engine

Kit Recommendation

Weight (approx.)
60SP .40 2-stroke / 60 4-stroke 3kg / 7lb
90SP .60 2-stroke / 90 4-stroke 4kg / 9lb
120SP .70 - .90 2-stroke / 120 4-stroke 5kg / 11lb

What are the approximate fuel consumption figures?
The typical fuel consumption based on 'average' flying is approximately
60SP - >0.4 fl oz/min
90SP - >0.55 fl oz/min
120SP - >0.7 fl oz/min

Can you suggest a typical test bench for running in the RCV?
During the 1st hour of running in, the SP engines may not run smoothly.  Test stands must be substantial  to cope with the larger than normal tortional forces (no ironing boards please!).  If you are able to start from scratch, below is a basic drawing of a suitable test bed.

teststand.gif (38320 bytes)
 

 

 

 

 

 

 

 

 

We have also kindly been sent a photo of one of our customers test stands.  Thanks to J. Carey, USA

What is a typical noise reading?
Noise readings are completely dependent on numerous environmental factors (ground cover, buildings, traffic noise) so specific Db figures are hard to give by any engine manufacturer.  To give an idea the following noise levels could be achieved at 7m:
RCV60SP  -  80 - 82 Db
RCV90SP  -  80 - 86 Db
RCV120SP - 82 Db upwards
The RCV however is marginally noisier than conventional 4-strokes, so in clubs with very tight noise limits (ie. 80 Db) consideration to reducing the noise through building and installation will be necessary.  NB. We do not advise rubber mounts due to the high tortional vibration.

Wouldn't  it be beneficial to cast the cooling fins to allow better air flow and better cooling through the fins?
You'll be surprised how many times we are asked this question.  The design of the cooling fins is dictated by the fact the SP series engines are cnc machined not cast.  We have however performed many tests and have found the direction of the cooling fins does not cause any cooling problems.

What would happen if the engine wasn't cooled properly?
The RCV design is intended to run at a reasonably high temperature due good thermal characteristics (see below).  Therefore insufficient cooling should not have adverse affects on the engine.  If cooling was not sufficient the worst that would happen is that the engine would lose some power and if really hot a propeller could melt.  
Thermal Characteristics:
On the model engine the clearance between the rotating cylinder and outer jacket is very small (<0.1mm). The heat is transferred across this gap by the oil film. On larger versions of the RCV oil cooling is employed whereby oil is pumped over the outside of the rotating cylinder to dissipate the heat from the cylinder.
The RCV design has excellent thermal characteristics with the rotation of the cylinder relative to the piston and ports ensuring that thermal distribution is very even throughout the engine. This means that thermal distortion is very low. Unlike a conventional engine there is not hot and cold side to the combustion chamber, and not hot exhaust valve to cause detonation.
 

If the engine is tightly cowled, do you have any suggestions to improve cooling?
The cylinder jacket has been designed to dissipate heat and when flying there is the added advantage of the engine being cooled with the airflow on the propshaft.  This does however require airflow.. If the engine is closed in a cowl, airflow needs are similar to other engines therefore the exit are needs to be at least 2 x larger than the air inlet area.  It is very hard to give a precise figure for this inlet, but we would recommend that at least 1 square inch is available for the inlet and 2 for the outlet.
I
n a tightly cowled model it is essential to arrange a deflection duct to scoop air over the engine.  A schematic of such a duct is shown below.             

                                            
cooling.jpg (9487 bytes)

What size props are recommended?
The RCV is a geared engine therefore the prop is turning at 1/2 the speed of the engine.   For this reason much larger propellers can be used.  Pitches would normally be between 10 and 14 inches (in general double that of a conventional engine). We do not recommend any propeller with a pitch less than 10.
As an example the props we use for much of our in-house testing are:
RCV60 - 16x12 propeller;
RCV90 - 18x12 propeller
RCV120 - 20x12 propeller. 
RCV Engines are able to supply propellers suitable for use with our engines for more information of the range of propellers available please

Can wooden props be used?
We always use and recommend glass composite propellers, however wooden propellers can be used if necessary and have been used successfully in some RCV testing.  It is important however to use a good quality / heavier wooden propellers because generally wooden propellers are too light and do not produce the flywheel effect.  RPM figures will be lower when using wooden propellers.

Where can I obtain a spinner for my RCV?
If you are finding it difficult getting a spinner for your RCV SP engine due to the large pitch propellers, Tru-Turn are able to supply a good range of spinners which are suitable.

Can these engines be started from the front by spinning the prop?  Or only from the starter socket?
We ONLY recommend you use the behind the prop starting method for safety reasons.  It is possible however, to start the engines by spinning the prop if that is your preference. You need to remember that due to the 2:1 reduction gearing, not only is the prop larger than on conventional engines, it is also spinning at half the speed of the engine, so the 120 size is not as easy to start using this method.

How does my starting adapter fit into my starter motor?
Take off the rubber cup and then unbolt the cup on the starter, revealing a shaft.  File a small flat on the shaft at the point where the adapter grub screw will grip to the shaft.  Fit the RCV adapter onto the shaft and tighten the grub screw. For full instructions see

How does the 'behind the prop' starting work?
With the use of a hand held electric starter (and the starting adapter) inserted directly into a socket located on the end of the crankshaft, the engine can be started from behind the prop. This turns the crank gear which then turns a gear formed around the base of the cylinder.'

Would it cause any running problems if  I rotated the engine but didn't keep the glow plug was not at the top?
No, but the fuel tank height would require adjustment to compensate for the different carb position

How should the engine be mounted?
The larger than normal tortional forces from the geared prop mean the engine needs to be very securely mounted.  Fuselage construction around the engine mount must be very rigid (bear this in mind when choosing a model) and test stands should be substantial.
Mounting Instructions:
The engine would normally be radially mounted on the same bulkhead that would take the nylon engine bearers for a conventional engine.  We recommend putting a reinforcing metal plate.  A mounting plate is now included f.o.c with the RCV120-SP and mounting plates suitable for the 60 & 90-SP engines are available from RCV.  For more details please   NB. We do not recommend using rubber mounts.

Troubles with starting
RCV engines are honestly about the most instantaneous starting of model engines providing everything is in order.  Starting difficulties can usually be put  down to the following.
1     A starter that is not powerful enough to spin the engine over quickly  OR an electric drill
2     Starter going the WRONG way (this is VERY common and a simple mistake to make) the starter will be going in the reverse direction to a conventional set up due to the gearing which reverses the direction of the crank for a given propeller direction. To check - just ensure that your propeller is turning ANTI clockwise ( viewed from front ).
3     Fuel should be 10% nitro synthetic based ( M T Duraglo or similar ).
4     Power Panels - these can be worse than useless - ESPECIALLY if the same ( small ) battery is also supplying the glow element voltage - what happens is that the starter pulls down the battery voltage reducing the glow - despite everything appearing fine when you do a glow test - an OS F plug pulls around 3 amps.
To start the engine ensure that the above are all ok and then :-
1     Open the main needle several turns from closed ( too rich is no problem you can always close it down after the engine fires - too lean and the engine will NOT fire at all )
2     OPEN the throttle wide - place your finger over the inlet and choke the engine until it is very "wet" feeling ( fuel may even drip from exhaust under such a situation - this is fine )
3     CLOSE the throttle to one third - energise the glow and make sure that the clip is a good fit ( I prefer two croc clips to any commercial clip ).
4     Apply starter - the engine will fire immediately and should continue to run - albeit roughly until the two needles are set.