RE: RCV91cd Chirping noise
Again, it does sound like you have the same issue. I must emphasise that this is a very rare problem. We have now produced many thousands of engines in the CD range and looking back at our service records have only seen this issue on 10 engines. The noise is a slight irritation but it wont cause any damage or loss of performance. The rectification is simple and straightforward.
Posted on: 6/29/2009 10:28 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8890523

RE: Can the carb unit on the RCV91cd be reversed?
Hi Yes its no problem to swivel the carb 180 deg Keith.
Posted on: 6/16/2009 6:35 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8855891

RE: RCV91cd Chirping noise
Hi The engine does have a problem which is easily rectified. The problem is that the cylinder bearing is loose in its housing when hot. At full throttle the cylinder pressure keeps the cylinder pressed up against the bearing so there is no noise. But at low throttle the vacuum in the cylidner on the inlet stroke sucks the cylinder downwards until the gears over-mesh causing the chirping noise. The problem will not cause any further damage, but it would be best if you return the engine to your dealer for repair. Thanks Keith
Posted on: 6/16/2009 6:31 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8855888

RE: RCV120SP mounting options
Hi Sorry about delay in replying Answer is that the position of the vent will have almost no effect whilst the engine is running. With the crankshaft whirring round at 12000RPM, and 20cc of gas trying to get into and out of the breather every cycle the interior of the casing is a very violent place and gravity will have little or no effect. Once its stopped I think that hanging the model vertically might help a little but dont think its that important. We've had engine hanging around here for years with little or no care and attention between runs and the'yre fine!!
Posted on: 6/16/2009 6:26 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8855882

RE: 58-CD idling around 4000
Hi Think the previous contributors advice is v good, thats certainly one method of doing it. Essential you get the throttle close to closed, so the pin method is a good one. And you can hold the engine up to your ear to hear when the flow starts. Would probably recommend that you start with a setting of +1/2 turn from where you can just hear the air flow starting. Another test you can try is to see if the situation is better with the glow battery connected. Get the engine completely warmed up then get it to the minimum idle you can manage without glow. Then reconnect the glow. If it speeds up the mixture is rich so try screwing the idle needle in. If it makes no difference the idle mixture is lean so try screwing the idle needle out. Idle > 4000 is extreme. Could possibly a carb fault, so if the problem persists after the above suggest you return it to the company we have transferred our model engine business to:- Weston UK. 01795 521030. Westons are now the main dealer for RCV and will handle all sales/spares/service issues. But for the US they utilise BJ's model engine service centre for servicing advice and spares:- BJ's Model Engine Service*, 51 Hillside Dr., Beacon Falls, CT 06403 phone: 203-888-4819, email: wbilljensen@cs.com Keith Lawes Technical director RCV Just had a thought. There should be a very tiny o ring around the idle needle to seal it. If that fails or is missing you get v similar symptoms to those you describe.
Posted on: 4/27/2009 6:14 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8718500

RE: Will SP's run safely on Bekra 10?
Hi walts We switched from endurance testing using part castor part synthetic to fully sythetic a few years ago. To be honest have seen no trouble with either so I'm confident its safe to proceed. EDL in particular we have found to be an extremely good oil, doesn't form carbon until higher temperatures than other oils. Only fuel we have ever had trouble with was straight castor. That caused misfires in mid range Regards Keith
Posted on: 4/7/2009 7:05 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8657094

RE: Another engine/prop question for Keith.
Hi Joe I think all the numbers you are getting are about right. Your engine seems to be giving a fairly healthy power output. The discrepancies in the numbers are due to difference in prop design which means that a 20x12 of one design will often spin at a different speed to a 20x12 of another design. In particular APC props are thinner and tend to spin faster than other props for a given power. The 20x12 APC in particular has very thin blades and spins a lot faster than a normal profile prop. This probably accounts for the main discrepancy. If you put on a standard 20x12 2 blade you would expect to be down in the mid 4000s. The standard prop power calc we use indicates that on the SP for a given design of prop (i.e. same blade shape, thickness etc) if you went from a 2 to a 3 blade prop at the same diameter you would expect to loose about 1100RPM. Cutting the prop diameter by 1/2inch would gain you about 200RPM. So if you had managed to find an identical form 17.5x12 3 blade Master airscrew you would expect to see around 4600. The fact that you are 200RPM lower than this can only be due to differences in the detail design of the prop, and is well within the sort of variations we typically see. The weight (i.e. mass) of the prop will not affect the max RPM, merely the spool up speed which should generally be pretty quick anyhow. Its actually a hot topic this one! We are starting to think that using larger props on the SP range and loading them down to the mid 4000s might be a good way to run them, as long as you have enough pitch in hand for your forward speed. The following thread covers a similar topice:- http://www.rcuniverse.com/forum/fb.asp?m=8635635 Anyhow hope this helps Regards Keith
Posted on: 4/7/2009 6:35 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8657061

RE: Prop too big?
Hi Josh Had probs viewing your video (v slow computer), but have managed to do it at last. Very impressive. Does look great, and I'd say the takeoff performance is pretty fair. How much does the model weigh? Keith
Posted on: 3/31/2009 5:24 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8633974

RE: Prop too big?
Hi Josh Thanks for the flattery!! Always susceptible to a bit of flattery. On the overpropping, its a very interesting subject. Firstly I am sure you are not doing the engine any harm at all, if anything you are probably subjecting it to little less stress than the more normal rev range of 5000+. If you think about it you are running at a more conventional crank RPM (i.e. 8800, which would be absolutely typical for a normal ungeared 4 stroke). By revving the SP engine higher as we normally do you do get an increase in power (as power = torque x RPM). However as the engine breathes less efficiently at higher speed the torque drops of somewhat so the net increase in power is not that significant. So as long as its enough to fly the plane then you are probably doing the right thing. Probably the main limiting factor would be the pitch. As the RPM goes down the effective maximum forward speed (4400 * 10 inches per minute = 40mph) gets a bit low. However the engine will unload in the air, the RPM will increase and prob give you enough in hand. To be honest we have always traditionally run the engines in the 5000-6000RPM range, but aside from the pitch question its probably more efficient to run in the 4000-5000RPM range, but then you do start to run into forward speed v pitch problems on some model. Also the prop sizes required to load the SP engines down to this speed become a bit impractical. So to sum up, it works well and it isn't going to do any harm so keep going! Regards Keith
Posted on: 3/31/2009 4:52 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8633955

RE: 90sp Vs 120sp for multi blade props
Hi Everyone My name is Keith Lawes. I'm technical director RCV Simple answer to your question is that the 120 could swing a much larger multi blade prop but at the time we specified them there didnt seem to be anything readily availble. If there is anything available now then we would be interested to hear about it. Also in general if you can fit a two blader it will be significantly more efficient. You can put the same prop on both 90 and 120SP engines, but the 120 will give you more RPM for a given prop and therefore more power. The rev range figures are a little misleading as in general the 90 will be towards the lower and the 120 the upper. Prop RPM v power is a cube law, i.e. to double your RPM needs 2x2x2 = 8x the power. So you dont need a very big increase in RPM between the two engines to give you significantly more power and performance:- If the 90SP swings a prop at 5000RPM and the 120 swings it at 5500RPM, its giving roungly 30% more power ((5500/5000) cubed!). Hope this helps Keith
Posted on: 3/26/2009 7:02 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8617889

RE: Chirping Noise during Idle RCV-58
Hi Erik From Keith Lawes, technical director RCV Engines Your engine does have a minor fault. What happens is that the cylinder is not tight enough fit in the cylinder bearing (the large diameter bearing its rotating within.) The cylinder should be a tight fit in this bearing. However on yours because its slightly loose when on idle the vacuum on the inlet stroke (when the piston descends with the throttle almost closed) will suck the cylinder down so that the gears overmesh. The gears overmeshing causes the chirping sound. At higher throttles the high combustion pressures force the cylinder up into its correct position causing the noise to disapper. Although not essential its probably best if you get this fixed. As you probably know our sales and service agent in the UK is now Weston UK. 01795 521030. This is a rare problem and your 91 should be fine. Apologies for the inconvenience and hope this helps Keith
Posted on: 3/19/2009 7:14 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8593432

RE: Hudson Flier Project
Hi Chevelle So with that weight and huge area you can probably get away with a 90. Think a 90 boxer twin would be ideal, shame we dont do one! There is an original Curtis (I think) Biplane hanging from the ceiling at Albuquerque airport. Fantastic original condition, and it has a big multi engine in it, cant remember if its a V8 or straight 6. But its amazing to see this huge engine suspended in the middle of this flimsy structure, with the pilots seat right in front of the 1/2 ton cast iron block of the engine!! Would hate to run into anything in one! The very best with the project Keith
Posted on: 3/9/2009 6:53 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8558465

RE: Hudson Flier Project
Hi Chevelle My name is Keith Lawes, I'm technical director at RCV. I'm afraid I would strongly recommend that you do NOT fit a 120SP into this model. Its very lightly constructed, and whilst the 120SP is a good motor, it does have double the torque pulses of a normal engine due to the 2:1 gearing on the prop. This is not a problem on a conventional model with a nice solidly built monocoque fuselage bolted to a set of wings to absorb the torque pulse, but on your model think it could be a major hassle. In fact I think with any single, your model would shake itself around a lot. To be honest I think you will have to expand your budget a little and buy a boxer twin. This will have smaller torque pulses and little or no mechanical vibration. These early planes always had balanced engines (typically a 4, even on the Wright brothers) as their very flimsy structures were not up to dealing with the vibration from the more widely available singles. Sorry to loose a sale but would hate to see such an interesting project have any avoidable problems, as with all new model there will be enough unavoidable ones!!! Regards Keith
Posted on: 3/5/2009 7:10 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8545861

RE: RCV Ebgine Fuel
Hi The previous contributor is completely correct. A conventional glow plug works by the catalytic action of methanol on the hot platinum coil during the inlet and compression strokes. The hot platinum coil causes methanol and oxygen to combine, creating heat which heats the coil further causing more reaction and hence the process is self propogating. Now I'm not sure but I think that conventional glow plugs wont have a catalytic effect on ethanol, so the engine will just stop once the battery is disconnected. If a special plug is availble we would be very interested to hear about it Many thanks Keith Lawes, RCV
Posted on: 3/5/2009 6:54 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8545845

RE: Vibration Comparison RCV Cd Vs other 4 strokes
Hi My name is Keith Lawes, technical director at RCV. Obviously would be easy to promise that the RCV CD range are the smoothest devices known to man, but to be honest all single cylinder 4 strokes are going to be very much of a muchness, whichever one you select. With a single the main dictator of vibration level will be capacity. This is partly mechanical out of balance forces (as you cannot fully balance the reciprocating piston with a rotating counterweight on the crank) and partly due to the torque pulses from the firings (negative torque during compression followed by positive torque during firing, the difference between the two being the net torque output). Both of these will increase pretty much linearly with capacity. Twice the capacity, twice the vibes. So the Saito 150 would prob have more vibe than the RCV 130CD. But of course it would also have significantly more power. If the 150 defeats your electronics its unlikely the reduction in vibe from the 130 would give you any safety margin. Prob the best route forward is a boxer twin. This has near perfect balance forces, and much smaller torque pulses for a given capacity. This is why this is the most common configuration for UAVs. Incidentally we do have UAV boxer twins under development, specifically designed to run on heavy fuel (JP8 or kerosne). They are pre-prototype and v expensive!! Prob your best bet would be a Saito or OS unless you have a definite heavy fuel requirement. Hope this helps. If you have any specific enquiries maybe you could contact me on keithlawes@rcvengines.com Regards Keith
Posted on: 2/9/2009 5:53 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8455892

RE: RCV CD series Upside-down
Hi Marc Its fine to run them upside down. In fact the majority are prob run inverted as this fits in better with most aircraft cowl shapes Regards Keith Lawes
Posted on: 12/22/2008 6:06 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8270200

RE: RCV 91 CD Problem
Hi Rad Timing sounds spot on and RPM is reasonable. You have obviously tried the mixture. But maybe have one last go to see if the idle needle has any affect. As you screw the idle needle in the part throttle mixture will become leaner and leaner, and should help to keep the glow lit. But if you screw it in too far the part throttle mixture will become so lean the engine will not run, even if the glow is connected. So please go through the following procedure. With engine stopped turn idle needle in 1/8 of a turn. Turn the main needle at least one turn beyond its normal position (This is because the turning in the idle will lean out the part throttle mixturem, but will also affect the full throttle mixture slightly so need to make sure the engine has enough fuel to throttle) Start engine. Take to full throttle and lean out the main needle in the normal way to get peak RPM. Remove the glow and close the throttle and see if engines part throttle behaviour is improved. If behaviour is improved stop and close the idle needle another 1/8 and repeat the procedure. As noted above always ensure you richen up the main before throttle up as idle needle does have some effect on full throttle mixture. You will know if you have closed the idle needle too far as the engine will either not start at all, or it will die lean when you open the throttle, no matter how rich you set the main. If this has no effect then will need to send to our service agent in the states, Bill Jensen. He is a very good man and will sort your problem! His website is:- http://www.bj-model-engines.com/ Start by forwarding him this thread. Many thanks Keith
Posted on: 12/11/2008 7:05 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8234604

RE: RCV 91 CD Problem
Hi Rad Its Keith Lawes from RCV Engines here hoping to help out!! Will the engine not even run flat out with the plug de-energised? 1/ Could you give me an RPM figure with the engine flat out. If you haven't run the engine in please put at least 10 minutes on it before doing this at lower throttle, then stop it to let it cool, then start it and put it flat out. 2/ Could you also check the valve timing. To do this remove the exhaust and carb, then put the engine to top dead centre between inlet and exhaust. You do this by aligning the key on the prop driver vertically downwards (if port is not visible at all you are at TDC between comp and power strokes so turn the crank 360 degrees). At TDC you should have equal amounts (a couple of mm) of port visible in the exhaust and inlet ports (this is the inlet/exhaust valve overlap, same as on a conventional 4 stroke). If theres significantly more port in one than the other then the engine will need to be retimed. This is straightforward but we'll worry about it if its the problem (which I think is unlikely) Thanks Keith
Posted on: 12/8/2008 7:36 AM by Author "keithlawes" in the forum "RCV Engines Support"
http://www.rcuniverse.com/forum/fb.asp?m=8224250