How to Start the RCV
Otto:
After reading your response, I have the following comments.
1. The RCV instructions, the ones that come with the engine from the manufacturer states " We recommend 10% nitro.... nitro fuels with higher than 10% nitro appear to offer no performance benefits". "Fuels must have a MINIMUM content of 15%, no more than 6% castor". In the instructions they DO NOT state a maximum oil content. I have checked with Powermaster and they confirmed that the oil content is as recommended/acceptable by RCV.
2. Yes I could put an 18" prop on the mustang if I extended the gear by about 1.5". If I did this it would not fit in the wheel well. I prefer to fly scale or semi scale models that LOOK like the real thing. A Mustang with the spinner elevated to the height required by the 18" prop would not look scale. I think you are missing the point by recommending that I fit a two bladed prop. Besides, the intent of this experiment was to try the RCV on the mustang for a couple of reasons. First I wanted to try to find something that would allow me to swing a four bladed or a three balded prop and secondly, I wanted to find an engine that would fit within the cowl. For these reasons, I purchased the RCV.
3. I disagree with your comments that I have changed too many variables. I have run the appropriate nitro content( AS RECOMMENDED BY THE MANUFACUTRER) and I am running above the minimum oil content (with the acceptable level of castor) RECOMMENDED BY THE MANUFACTURER. So I believe that your comments about my deviations from the recommended are WAY OFF BASE.
4. I would agree that the engine was intended to turn a large prop at a slower RPM. When I purchased this engine, as I said above, I was trying to find an emgine that would allow me to turn a four bladed prop and fly a plane faster than 46 or 60 mph.
Having said all of this, I will present some additional observations made over the last two days of flying the combo. I currently have approximately 12 flights on the plane/engine combo and have flown it with four different props. I have put a total of approximately 3 hours running time on the engine.
On Thursday and Friday I put about eight flights on the H9 P-51 and the RCV 90 combo. During the course of these flights I let a few of the giant scale warbird pilots (I was at a Fly In in Edinbug TX) fly the model with difefrent props. They other pilots also concurred with my speed estimates. Incidentally, we had the opportunity to fly just after a Ziroli F-8 Bearcat with a BME 102cc engine (clocked at 139 mph during a previous event), so we were using the Bearcat as a rough gauge of the speed of the P-51 and compare how fast the P-51 covered the same length of runway as compared to the Bearcat.
1. Zinger 16" x 10" four bladed prop. 4500 RPM. Plane flew rather slow, approximately 60-65 mph. I thought the model flew too slowly, didn't have much vertical and struggled thru a loop.
2. Zinger 16"x10" four blade cut to 15"x10". 4750 RPM. Marginally better than the 16x10 but still not very impressive. Still same problem with loops. Speed is aproximately 65 mph
3. Zinger 16"x10" three blade. 5100 RPM. better flight characteristics than either of the four balde props. We are getting there. Speed approximately 75 mph
4. APC 16"x12" tow bladed prop. 5700 RPM. Much better than any of the other combos, but still not fast enough to replace the YS 91. Estimated speed is 80-85 MPH.
As you can see, the two bladed prop get the plane closer to where I wanted to be, but it just didn't fly as well as hoped for with the four blade props. As I said in my previous post, I don't think that this is the combo I want for a warbird. After having a number of fliers fly the plane and discuss the appropriate applications for the engine. I believe that the consensus is that this engine would do well in a scale plane like a Taylorcraft, Stinson or maybe a WWI bipe.
As I said in my previous post, it was my intention to try this combo and report back to the forum. I have no ax to grind with anyone (Otto, RCV or anyone else) but I wanted to present my findings so that modelers could make an informed decision. My thoughts are that (this may seem obvious but I wanted to try the combo) if you want to go fast with a warbird type of model, look at a two stroke or possibly a four stroke and a two blade prop.
Ed