Captmicom

Hi Ed,

Picking your prop is like being on the "Bachelor"! You have so many choices and so little time. It will still be that sort of personal preference thing. First narrow down your selection. The old props are still out there but I would look at the newer more efficient props like Xoar or Falcon. The prop size that you use will depend on a bunch of stuff but the best guess is to look at your RPM. The power curve for the RCGF 15cc engine starts at about 7800 RPM peaking out at around 9500 RPM. Any higher RPM over that is a waist. Put the prop on and start the engine up. Check the RPM on the ground. Remember that when your plane is in the air the engine will unload from 700 RPM to a 1000 RPM more. Each one of us will have different readings based on where we live. My back yard is almost 4700 ft. ASL. In the summer time our air density here can rase that up over 7000 ft.

So test your engine with a couple different sizes of prop. and go with the one you like the best.

MTK

That's a lot of prop for a 15cc. The 15x6 is about right for break in and after. But it is the right amount of power for the 77" span plane.

A 30cc for the bigger stik is also about right mostly because the area is so large. The weight is low enough where the 26 cc can fly it but I'd put the 30cc in it and throttle back. Gas mileage would be terrific.

rt3232

My Feedback: (6)

Guys I will add that the weight can also be a deciding factor, even when the engine is turning in the middle of the torque curve.

Just my 2 pennies worth

Cheers Bob T

Cjkuehl

Thanks for the advice everyone. I attempted to order a 15cc and a 30cc twin from RCGFUSA but kept getting an error. I sent an email explaining the issue and hope to get it resolved soon.


Pretty excited to be getting into gassers!

nh4clo4

My Feedback: (33)

Thats what I was thinking, I typically use a 16-8 on my 20cc

Captmicom

UP here I spin a 16x8 Falcon on my RCGF 15BM just fine. I am swinging am 18x6 on my v2 RCGF 20cc RM.

Bcolici

Joe,
What prop do you recommend for the 10 cc in a 6.5 lb aerobat at 10 ft above sea level?
Also i purchased the motor from RCGFUSA a few months ago and havent fired it up yet.
I noticed that the serial no. is stamped 2x with different numbers??
Tia

Captmicom

Hi Tia,

First let me say thank you for your engine purchase. Ok I can tell what I did for the beta test 10cc BM engine for Dec. last year. We took a 60 size Ugly Stik for the test flight. I through the thing together at the field. I grabbed a 14x7 prop out of the prop box and we went out to fly it. I don't remember what brand it was cause all of the paint had been knocked off a long time ago. It is one of the black fiber filled ones. Might be a master air screw. Anyway at start up it tached out a 8000 RPM on the ground. In the air it unloaded to 9000 RPM. On radar it was 70 to 75 MPH consistently at full throttle. It would do anything that I wanted it to including hang on the prop at about 1/2 to 2/3 throttle.

If you are going to do aerobatics with it I would look at maybe 13x8 or 14x6. It will depend on the prop brand as well but if you have these sizes laying around it will be a good starting place.
It would also be great if you posted some of your run info here on this thread after you fly it.

Captmicom

Tia,

I forgot to tell you about the two numbers on your engine. We started tattooing a small number on the blocks late last year to separate our engines from non-warrantee knock offs. The block tattoo number has a direct correlation to the registered serial number of the engine. If we tried to put the whole SN on the engine you would need a microscope to see it.

Bcolici

Thank you Joe.
I'll keep you posted on performance.
I was hoping the 14 inch range would work. Right now all i have is a 13x6 apc. Going to get a couple of xoar props in the 14 inch range.
Have to tidy up a few more things before i maiden.

karolh

My friend Dale has a Hangar 9 Ultra Stick 60 with an RCGF 15 which hauls it around with great authority.

hsukaria

I have a GP Giant Stick and it weighs 15-16 lbs. You need at least a 30cc on it. A 40cc Twin would be really nice if you want to spend the extra money. The Giant Stick was original designed for very heavy gassers with magnetos. When I had a 30cc on it, I still had to put 1 lb of dead weight on the nose. I have replaced the 30cc with a 50cc recently just to balance the CG without the use of ballast.

mach2

My Feedback: (5)

Hey Joe, does the RCGF 32cc have two piston rings like the 60 and 26BM?

Captmicom

No it only has one ring...

dwaynenancy

My Feedback: (62)

Anybody know where a listing for putting a gasoline engine on the new Tower's new .60 Kaos ARF can be located?

Captmicom

Hi Dwayne,

What kind of info are you looking for? If you are looking for a gas engine for the .60 Kaos then an RCGF 15cc BM would make it fly plenty fast. Mount it sideways and us a 30T muffler on it. The 30T muffles sell in a set but that will give you a spear for future use.

MTK

Or the OS GT15 or GG15. The GT has a CDI/sparker while the GG has glow plug for petrol (no CDI needed, saving 3 1/2 ounces). Beware tho, the 15cc engines turn 14-15" props so clearance might be a problem. You could put a 12 incher on it like an APC 12x12 which will turn at lower rpm of around 8500 give or take. It would be a good experiment

Bcolici

A front mounted carb might make the install easier as well,
but I thought this was the rcgf engine thread.

ahicks

My Feedback: (2)

Re: Kaos power, most 15's weigh as much as a DLE 20. I can't help but believe that even though a 15cc engine would power it really well, it would weigh a TON, and very likely have CG issues.

If you want gas, thinking a 10cc engine, with it's significantly less weight, might be the smarter choice.

dwaynenancy

My Feedback: (62)

I couldn't find any info on the .60 Kaos anywhere so that's why I asked the question here. I have mounted the engine inverted with about 1/16" or 1/8" clearance around the intake. If there is another place about the Kaos I would go there.

MTK

Try the Classic Pattern sticky on the Kaos

Cjkuehl

Engines arrived today and they look great. Is there a favorite ignition battery for the 30cc twin? I assume the 15cc could use a smaller battery?

MTK

The CDI uses the same energy to spark a 10cc single or 85cc single.

But why use a second battery at all? I recommend the Tech Aero Ignition Battery Eliminator (IBEC). It powers the CDI from the main, radio battery and actually costs less than a second battery and second switch. The main battery should have about 1800ma capacity minimum and 6 volts. I suggest you take a look on the Tech Aero Designs website.

Bcolici

Another option is to make a small solder modification to a rcxel ignition kill switch and then it can be used as a ibec .

Captmicom

I use 6v 1600 MhA 2/3 "A" packs normally. But if I need a bit more weight up front I will use a 6v 2200 MhA pack. On the smaller planes I use 4.8v 1500 or 1600 MhA pack. Our new CDI systems are not power hogs.

As for the IBECs I say be smart save your money and use two separate power sources.