Damnathius

I finally got the opportunity to run my new RCV 120 SP. For the break-in prop I used a Zinger 20x8-14, and ran the engine burbling rich between 2000 and 2500 RPM for about an hour and a half total. (12-15 minute run times with total cool down between) Fuel used is Byron 10% nitro, 16% lube oil, which is pretty close to the manufacturer's specs.

The first run was rather noisy, with moderate gear noise, but with each subsequent run the gear noise decreased. The noise is still present, but simply adds to the interest of the engine. I've read about excessive vibrations on these engines, but mine seems pretty smooth... Smoother than my Saito 150, for sure.

Yesterday evening I switched to the Zinger 24x10 I plan to run on the plane, and leaned the engine out for some performance. Best RPM with this prop was a consistent 4300 RPM, which should increase a tad when in the air. I think it will turn more, but I didn't want to push the engine. The untuned (rich) idle was a reliable 1000 RPM. Man, that thing looks cool sitting there spinning that 24" prop at that speed, and it's amazing how many firings it can miss and still run. Transition from idle to top speed was pretty quick considering the rich idle setting, taking about a second.

I'm quite pleased with the engine, and am wishing I had the money to buy the 60 and the 90! Someday...

Regards,

Dave

Update:

Checked RPM reading with a digital tach yesterday, and found the 24x10 to be turning at 4100-+. Will check RPM with 20x8-14 today. Most likely I will order a Master Airscrew 24x8 to get above the 4100 minimum full throttle RPM.

Damnathius

Recieved the Top Flite Powerpoint 24x8 prop last week and checked RPM. Easily spins at 4400 RPM. Looks like the Nieuport will be flying with this prop, as it is substantially above the 4100 minimum full load RPM, and will most certainly unload a bit in the air.

I have the engine mounted to a Craftsman workmate(?) sawhorse, and use a 25 lb. bag of shot on top to keep it in place. At full throttle, this engine just begins to inch the sawhorse along the concrete. Of course, the engine's mild vibration probably has something to do with the lack of traction on the legs, but it's still impressive that it threatens to move the stand. This engine definitely produces some thrust.

Starting: With the engine dead cold and a good wet prime, most of the time (4 out of 5 times) this little beast will start on one brisk flip of the prop! When it doesn't start on the first flip, 2 or 3 flips has it off and running. Occasionally the engine will start backwards, but I think that this is due to "easy" flipping, which carries the prop against the backside of the compression stroke instead of through it.

Two weeks of easy work and it should be in the air on the Nieuport. I can't wait to see how this powers a 13 lb. WWI bipe.

lokeetl

Dave,

Keep us up to date. Heck, I'm interested!
Thanks for your info. As a RCV 120 owner, I'll take all the information I can get! It ONLY helps.

Chip

shupack

i'm not sure if i'm reading your posts right, but i think you're misunderstanding the difference between static and dynamic thrust. you can equate blade pitch to how much of a slice of air the prop takes each revolution. in an ideal world a 24-8 will go 8" per revolution, a 24-10 will go 10 inches. (in the real world you have to account for drag, inefficiency in the blades, air density, and some others)
when you have the engine strapped to the bench it's trying to go forward so you're just blowing air like a fan, in the plane it is moving forward, so the prop is pulling through the air, where you get the unloading. with a lower pitch prop you'll get more static thrust, but once in the air and moving there will be less thrust than a same diamter higher pitch prop. ie ducted fans, they have a verry high pitch, and on the ground can barely get rolling because their blades are stalled, but once they're moving and have air coming into the blades, they cook.

another example is a stick shift car. start out in first gear (low pitch) and it's easy, you accelerate from 0 till about 20 easily, and if you floor it it pulls pretty hard, but once you get going the engine unloads because the ground is coming at the tires faster than the gear accomodates (unloads) try second gear (high pitch) it's tricky to get moving because you don't have the low speed torque (blade stall) but once up to about 20 the engine will accelerate the car happily up to 40 untill you're past the speed range for that gear too.

this isn't an exact analogy because with a model engine there is only one speed, the fixed pitch. as the airplane accelerates the blades will unload and rpm will increase for a given throttle setting, unless the airframe is draggy enough (with a bipe i suspect it would be) you could even overspeed your engine with too low a pitch prop. I think otto would give the best advice on which prop to use with your neuport, but i think you'd be happier with a little higher pitched prop, and you can cruise at the same speed with a lower throttle setting and lower rpm=more realistic flight. and IMHO maximising static thrust is only good for hovering and torque rolls, which I would guess you're not going to attempt with a wwI bipe, but I could be wrong
sorry if that sounded lecture-ish, but i just spent a month with my inlaws, both teachers, they rubbed off a bit

Damnathius

That's all very interesting, shupack. Regarding you last paragraph. I have spoken to Otto about prop sizes for this model, and 24x10 was one of the recommendations. However, you'll note that with the 24x10 I was only getting 4100 rpm, which is the recommended minimum full load rpm. Not wanting to ruin this engine with such a loading, or wear it out prematurely, I decided to try the 24x8, which gave me a 300 rpm increase to 4400 rpm, which is still a great deal away from the 6000 rpm max for this engine.

It's true that I do not want to hover, but I don't believe using the 24x8 will create any problems. Of course, the true test will be in the air. I have two props to try if necessary.

Thanks,

Dave.

shupack

hit the nail on the head there, theory is all well and good, but operation is what counts. good luck.

silkwah

My Feedback: (1)

I am a new owner of an RCV 1.20
I am at the front end of installation in a 110"
Rascal. Would very much appreciate advice on proper
props for this combination.
The choice of engine is to avoid upside down engine installation.
The 1.20 RCV fits perfectly with 110 Rascal's cowel
on.

Damnathius

That should be a nice combo, Bill. Those Rascals are great flying planes... I have a 40 size I've been flying for months now.

I can't recommend any props for the 120 as all I run is the 24x8 on my Nieuport, which flies it exceptionally and has more power than I need in that 14 lb. bird.

See this thread: http://www.rcuniverse.com/showthread...43&forumid=157

Davee

RCV Engines

Hi

As well as Dave's suggestion, it may also be a good idea to try a 20x12 prop. We do not have any direct experience with the 110 Rascal model ourselves but we know the APC 20x12 is a good prop for running in and it will turn the prop at approx 5150 rpm which should be good for flying.

I hope this helps.
Regards
Laurenne

silkwah

My Feedback: (1)

Thank you for your response. Am at the point of adusting firewall thickness to have the RCV shaft
extend from the cowel by the correct amount.
I shall buy a 20X12 prop as soon as I find a source. Would you suggest two other props to try ?
Appreciate the response.

I have been using YS 20/20 as fuel.Most engines respomd to it. May I use that fuel on the RCV 1.2 ?

Silkwah

RCV Engines

Hi

Firstly with regard to YS20/20, I am unsure of the makeup of that fuel. I have just emailed powermaster for more info, then I will be able to let you know whether it is suitable for the 120SP.

With regard to other prop sizes, some of our other recommended prop sizes for the 120SP are 18x12, 18x14, 18x16. These are all APC props. It does appear that US modellers also have some success with Zinger wooden propellers up to 24x10. If you do want to try these, I would recommend doing so after you are familiar with the performance of a 120 on our recommended glass composite props, as we have found that wooden propellers are sometimes too light to produce the desired flywheel effect.

I hope this helps and I will let you know about the fuel once Powermaster have contacted me.

Best regards
Laurenne

silkwah

My Feedback: (1)

Thank you for your clear response

silkwah

RCV Engines

Always happy to help.

RCV Engines

I have just heard back about the Powermaster fuel. The content of the YS20/20 is 20% Nitro and 20% Oil. Although this fuel is very good for some engines, this is not recommended for the RCV engines.
Our engine's compression ratio has been set to run on 10% Nitro, more nitro will increase the compression ratio therefore 20% nitro would cause too many stresses.

The RCV SP series engines are a little more sensitive to fuel selection than other 4-strokes, so we would recommend you use a fuel containing the following - 10% Nitro ; 14-18% oil (including up to 7% castor). There are numerous fuels which have similar make up to this.

If you have any more queries, don't hesitate to contact me.
Best regards
Laurenne

silkwah

My Feedback: (1)

Laurenne-
Set my 120 RCV firmly on a test stand.18x12 APC prop. good fuel.OS F plug. plug hot.
Using a brand new Hobbico starter powered by a standard 12v battery and checked for proper rotation. Engine difficult to turn over. makes a clanking noise. No engine start. Starter burned out!

Do you have a preferred starter or technique to
make this beasty run?

Rather diapointed
My engine guru (also owns a 60 RCV) has never run or tried to run his 60. My guru is a knowledgable
engine man and I remain baffled.

HELP

silkwah

Damnathius

Bill, did you use the starter adapter? These things are pretty tight at first and don't respond well to using the prop to start at first. After break in, flip starting with the prop is easy.

Oh, and try connecting the starter to a car battery.

silkwah

My Feedback: (1)

Damnathius-

Thanks for the tips-
I did use an adapter and did try car battery.

No joy

silkwah

Damnathius

Hmm. What happens when you turn the engine over by hand? Any "clanking" noise? Were you able to get it sloppy wet on the prime?

silkwah

My Feedback: (1)

Turned by hand - not as audible.

Yes we got a sloppy wet prime.

we think the starter did not have enough torque
nor enough rpm.
Will get the best Sullivan TourqueMaster starter before we try again.
Thanks for continued interest.


silkwah

RCV Engines

You are right. It is most likely that the starter you used didn't have enough torque. We generaly use a Sullivan Hi-Torq Starter -so the Sullivan Torque Master should be perfect.

Once the engine has been fully run in, it will be even easier to start.

If you do have any more problems, please let us know as the engines are generally great starters.

Best regards
Laurenne

silkwah

My Feedback: (1)

Laurenne-

Got the Sullivan Torque.

It sure turns that 120 RCV

Raining hard 1:32pm EDT

Will fire up Mon , next

Thank you very much,


Silkwah

RCV Engines

Hi Bill

I am pleased that the you are now able to get the engine started. Hopefully the weather will be nice for you on Monday

Regards
Laurenne

silkwah

My Feedback: (1)

Thanks to all who provided guidance re:my 1.20 RCV

Happy to report, when all things were right
it started on first try yesterday.

This is a stump puller!!!

Silkwah

RCV Engines

Thanks for the feedback.

If you ever have any more questions, don't hesitate to ask.

Best regards
Laurenne