flywilly

My Feedback: (121)

Hey David,
Congratulations on your engine review in the latest issue (whatever month it actually is...). Great to see a rear exhaust 'classic' .61 getting some 'face time'. The article was quite well done with some nice photos and good information. When will we see the YS classic 61 reviewed? . I'd love to see a 'we visited' article about Don Carlson and RCAIIR.
Geez, and I thought you were an electric guy.
-Will

doxilia

My Feedback: (3)

Hey Will,

thanks for the kind words. Glad to hear you enjoyed the article. I have yet to see the published version but I'd heard it was out.

I'm glad FlyRC published this as I've generally liked their engine review format. Space is always limited however so the published article is a condensed version of a fairly in depth review in the style of Clarence Lee and Peter Chin (not with their unparallelled experience and knowledge however). In short, I became quite familiar with the beast and would be happy to shed any further info on the engine should anyone have questions.

I agree with you - it would be nice to see a review of the YS as well. Doing a story on Don is also a great idea.

And just to be clear, I'm a renaissance man - I like different kinds of fuel and power... I will always have a soft spot for Italian engines.

David

PS By the way, I believe Rick also has a review of the Spektrum DX9 in the current MAN!

flywilly

My Feedback: (121)

Hi David,
I like the 'renaissance man' appellation! I am a dedicated glow guy, though I played with electrics 30 years ago I haven't been motivated to try the 'new' generation of epower. I will say that I fully support it as it is the best thing to happen to powered modeling in years - making it very attractive to modeling newcomers and hopefully encouraging more people to join the hobby. The benefits are obvious to experienced modelers and I believe E-power has been instrumental in increasing the number of pattern participants who want to compete without 'enjoying' (or enduring) the glow experience.
I do have a few questions about the NovaRossi:
1)what is the difference between the R61F Speed/13 vs the R61F (bluehead)?
2) How are the headers held on? Just friction? What is the white material surrounding the exhaust port? High temp teflon?
3) You only tested the engine with the 9mm carb, how much performance increase would you anticipate with the 10mm carb? The old YS .60FR had a massive .452" (or 10.8mm) carb, but with the pressurized fuel system and very similar performance.
4) Considering the 'long stroke' design (same bore,stroke and carb intake as a Hanno Special) how do you think the engine would perform with larger propellers (12x11, 13x9, etc.)?
5) It appears in the magazine photo that the exhaust port is 'V' shaped, similar to the Nelson replacement liner for the Hanno. Are my eyes deceiving me? If that is the case, I am quite curious about the lugging power of this engine.
Thanks for your efforts! Maybe I'll get my a** in gear and do a review of the YS Classic myself.
Regards,
Will

doxilia

My Feedback: (3)

Hi Will,

excellent questions. I'll see if I can answer some inline below.

David

Quote:

Originally Posted by flywilly

Hi David,
I like the 'renaissance man' appellation! I am a dedicated glow guy, though I played with electrics 30 years ago I haven't been motivated to try the 'new' generation of epower. I will say that I fully support it as it is the best thing to happen to powered modeling in years - making it very attractive to modeling newcomers and hopefully encouraging more people to join the hobby. The benefits are obvious to experienced modelers and I believe E-power has been instrumental in increasing the number of pattern participants who want to compete without 'enjoying' (or enduring) the glow experience.

Your philosophy about e-power sounds very much like mine. I have enjoyed dabbling a bit with the small electrics and just recently have been compelled to try something larger so the Super Chipmunk 120 was the first "big" project. I plan to also do some other 60 size electrics in the future possibly including a Saphir I, a Calypso and a Tiger Tail IV. Time will tell...

Quote:

I do have a few questions about the NovaRossi:

1) What is the difference between the R61F Speed/13 vs the R61F (blue head)?

Although I haven't examined it, my understanding (also confirmed by NR) is that the blue head is an older version and primarily has different exhaust timing. As you correctly point out that these are long strokes, the blue head behaves more like one producing power at lower rpm. The "Speed/13" is the high timed version which despite still being a long stroke (same geometry in both) is able to turn small props at impressive rpm's. In a sense the Speed/13 behaves more like the vintage classic Rossi FIRE but it's internal design is much more efficient. Some of the details are "touched upon" in the review but lack of space prevented further elaboration. I went into much more detail in my original complete review. Once the FlyRC issue is no longer on the stands, I'd be happy to share it with you.

2) How are the headers held on? Just friction? What is the white material surrounding the exhaust port? High temp teflon?

I find this is a very nice feature of Rossi and NovaRossi engines. Incidentally, both have the same lug mounting dimensions as well as exhaust flange dimensions. RE engines can use headers and adapter from either company. The new NR (pun intended) headers and pipes are a refinement over the older Rossi style. The RE engines have a circular exhaust flange built into the crankcase. It has an annular groove which "captures" a silicon rand if you will. The rand is molded with a protrusion which insets into the groove so it doesn't dislodge. The rands come in different colours but are primarily white. My smaller NR 528 RE came with a blue rand which uses the same system as the larger 61's.

The headers are basically held on with a spring which wraps around the cylinder. While at first I thought this wasn't too aesthetic (given the cool looks of this engine), the springs actually nest in a space that has been thought about in the design of the engine and crankcase. In other words, the spring doesn't vibrate or move when the engine is running and tucks in just below the larger finned cylinder portion. The 528 even has two little eyelets that allow two short springs to be used instead of the wrap around but I've grown to quite like the latter style. The header is backed by a metallic ring which has two small holes which capture the ends of the spring. You basically install the spring on one side of the ring, attach the header to the engine, wrap the spring around the cylinder with a pair of needle nose pliers (being careful to not rub and scratch the case) and stretch it until it reaches the other end of the ring. It sounds tricky but it's not.

The nice aspect of this mounting approach is that the header is "soft mounted" so it prevents stress cracks at the header pipe, flange junction with a Macs or Hatori style header. Since there are no screws holding the header in place, it flexes slightly if you try to dislodge it. This would in principle salvage the crankcase exhaust flange in a crash. The headers are made of a softer aluminum alloy which would break before the engine case would.

The same system was used on the vintage Rossi's but those engine used only a simple silicon ring which didn't have a "backing" flange as the new rand does. The good news is that the new rands and the current NR headers fit perfectly on either vintage Rossi's or the new NR's. The rand completely captures the header junction so there is no metal to metal contact between header and engine.

Another benefit of the round inlet headers is that they can be rotated slightly (limited only by the spring wanting to rotate the header back into position) which not only allows one to alter the height of the header somewhat but also allows one to offset it from centerline. This is ideal with inverted installations where there is a nose gear which would interfere with a straight back header position. With YS engines we typically use "cranked" or offset headers in Aurora/Atlanta type installations. With the round headers, a regular fuse top type header can be used and rotated slightly to put the pipe off to the side a bit where the NG is located.

I am actually setting up a glass DB60 with a vintage Rossi SE vertically mounted and thought I'd use the Rossi SE header adapter (flange to round exhaust) and one of the new NR headers. Unfortunately, the combination of the adapter flange and the standard Rossi or NR header puts the pipe a little bit too "far out" along the fuse side. A tight bend header is really needed for vertically installed SE engine classic applications. With the engine side mounted, the headers work fine as they put the pipe far down enough and below the wing as needed.

3) You only tested the engine with the 9mm carb, how much performance increase would you anticipate with the 10mm carb? The old YS .60FR had a massive .452" (or 10.8mm) carb, but with the pressurized fuel system and very similar performance.

Yes, I wanted to test the 10 mm carb but I didn't have one available. However, my understanding is that the 10 mm carb results in a somewhat "peaky" performance which can result in lean runs. I suspect that it may be smoother in combination with a pump. That said, I wouldn't expect an increase in performance of more than 10%. 5% is more likely. That said, to my mind the real advantage of the 9mm carb is that it has a servo adjustable high speed mixture. The way this is designed results in a 160 degree rotation of the needle (about the max a servo can deliver given the rotary nature of the linkage at the carb) altering the mixture only slightly. In other words, the control is "exponential" in feel so to speak. One can take off with a full tank and use a "full back" lean needle control. As the fuel level drops and the mixture becomes increasingly lean, one can "push" forward the mixture making it richer. It likely also has application in inverted flight if the fuel tank is not centered on the carb intake. The ideal setting to my mind when tuning the engine is to have a needle position of "neutral" or centered before take off. This allows one to either richen or lean the run as needed.

The 11 mm inlet of the YS engines was/is possible due to the metered system. I can't think of any classic 2-strokes with such a large carb bore that wasn't also being "delivered" fuel by a metered or pressurized system. I am rather curious to see how the new "Classic" shorty compares to the Speed/13 - not only in terms of performance but also in terms of fuel consumption. Carburetor performance of the Speed/13 is very smooth and reliable once dialed in. Even with the 9 mm carb, it is still able to deliver in excess of 2.4 bhp on 10% fuel.

I suspect I'll end up using the engine in an Exception. When I do, I'll likely test the engine again with higher nitro content (but not more than 20%) and lower oil content (no less than 15%). My tests were done with 20% oil content. Those two fuel changes combined will likely yield another 5% power boost - just a gut feeling.

4) Considering the 'long stroke' design (same bore,stroke and carb intake as a Hanno Special) how do you think the engine would perform with larger propellers (12x11, 13x9, etc.)?

The largest prop I tested was a Xoar 12x8 - a 27 gram prop which tached just shy of 11K. I didn't want to load the engine up more than this because the stock exhaust setup I was keeping constant wouldn't have been well suited to the larger props. Even with the 12x8, the stock exhaust "felt" slightly short and I suspect that one could achieve higher rpm with a longer exhaust and higher performance fuel. With such an exhaust setup, I suspect that the engine would deliver comparable performance to a Hanno on a larger 12x10 or 12x11. Somewhere sub 10K.

In other words, the engine tames down and becomes a more typical long stroke when loaded up but where it really shines is when it is allowed to spool up. In a sense, despite it's long stroke design, the exhaust timing and port design make it behave more like a short stroke on lighter loads. It would be interesting to compare the standard timed version to the high timed Speed/13 with larger loads to see which engine is better suited to "long stroke" applications.

5) It appears in the magazine photo that the exhaust port is 'V' shaped, similar to the Nelson replacement liner for the Hanno. Are my eyes deceiving me? If that is the case, I am quite curious about the lugging power of this engine.

I have yet to see the photos that were selected for the article. I took an extensive amount and supplied the entire library. But yes, the exhaust port sleeve and crankcase work needs to be seen to be appreciated. All gas flow and lubrication design in this engine is optimized. I'm not quite sure what you mean by V-shaped but there are two grooves in the sleeve and case in the exhaust nozzle area that assist in the gas flow during emission. There are also two boost ports in the front of the case which are coated with a Teflon like ceramic material. The side transfer ports are also coated with this material.

Lugging power certainly remains to be tested ideally with a longer than stock pipe setup. However, my feeling is that there are other engines like the YS long strokes, Hanno and OS RF that might be better suited to larger load props. The Speed/13 really seems to be in its element on 11" props. The prop which gave me the best bench performance and behaviour on the stock exhaust was a Falcon 11x8. Nice props very similar in design to the APC's at half the weight. Rev-Up11x7.25 and 11x7.75's allowed the engine to scream but resulted in a slightly more sensitive engine. The Falcon and Xoar wood 11x8's are likely the best candidates for this engine. However, flight performance remains to be tested and it is possible that APC's may pull better than the wood props. Actually, there are a few folks who might have some flight performance insight into this.

Quote:

Thanks for your efforts! Maybe I'll get my a** in gear and do a review of the YS Classic myself.
Regards,
Will

My pleasure Will. It was a fun project and I have Buddy (William Shores) at SMT and Dave Phillips II to thank for the opportunity to review the engine.

David

speed-panzer

My Feedback: (1)

David, following with great interest...
It would be real cool to read your NR R61F review once you think it could be shared to some 2stroke glow engine nuts guy overseas. Bought both the blue head R61F and the Speed/13 last year, and I am still undecided which to try first, far to speak of into which airframe to install those...

Dominik

dphill2

My Feedback: (1)

David,
To help answer one of Will's questions about the 10 mm carb. I talked to the Nova Rossi engineers about installing a inflight mixture control on it when we visited the factory. He told me that it was not a problem.
He took a 10 mm carb and installed the mixture control handed it to me and ask to test it and let them know if it would clear up the "peaky" performance . As of this date I have not had a chance to test this set up but I have flown the Speed 13 with a 10 mm carb. and it does have a real fine needle. I do know that you can have the 10 mm carb with a inflight adj ..
PS. Great job on the article !!
Dave Phillips