balsa1

Hi
Yes on my nitro motors I did just that but with the 4 strokes I found on my 48's about 8000-8500 was the best so depending on what I wanted juggled prop dia. and pitch to do what I wanted more lift or more speed so that the loading keep me in this sweet spot that seems most of the time where the torque curve peeks not being used to the gas motors I rely more on the tackometer to keep me there I think captmicom pretty much gave me that info in that I will try the 18-8 and use that as the key even though are elevation may be different the sweet spot should be close to that thanks Les

mach2

My Feedback: (5)

Ahicks, I get what you're saying but there are ways to know if you're running to lean without a tach. First off, I don't think I run the risk because I always start out a little rich and burbly since a rich motor will almost never die on you in the air. Then I gradually lean it out from there until the burble stops and she runs nice and clean sounding. I don't try and ring out every ounce of top end power because I always over power my planes with big motors. Also, you'll know if you pull vertical and you hear the engine losing RPM, it's too lean. It should sound steady and strong vertical.

As for the props, I didn't say I "under prop" the motor, just start out with one on the lower end of the suggested range. Since I have an idea of what I want to try with it I'll usually have a couple different ones. Example, with my RCGF 60cc I think it recommended something like 23x8 24x8 22x10. I usually use 3D wood props from Redwing (very similar to a Vess). Since I'm not out for speed I wanted to try the 23x8 and 24x8 so I got those. So to start out I use the 23x8 for a few tanks and then throw on the 24x8. With that particular plane I liked the way the 23x8 flew. Anyway, I'm not a proponent of using props that are to small. As you know I'm a big fan of the 17x6 on the DLE 20 (on a revolver), while many others like to ring them out. Which leads me to my last point. I'm not a big speed freak. Generally, I only use full throttle while performing maneuvers that require it. But that shouldn't be a factor because either way, it's always the goal to have the engine tuned well and use a proper propeller for whatever type of flying were doing.

mach2

My Feedback: (5)

Joe, yes let me know how he likes the prop. I'm hoping a carbon will spool up a little faster than the wood props. If I can keep the same amount of pull while adding some pep, that'd be great! It'll be another venture into finding the right size and pitch for the carbon prop...

mach2

My Feedback: (5)

Well 4 strokers are a different animal. I would definitely use a tach on those. It's pretty difficult to hear variations in RPM on a 4 stroke. I've dealt with 2 strokes in one way or another all my life so maybe I've developed an ear for them.

I'm not saying people shouldn't use a tach. I'm just saying I don't think they should base all tuning on them because you can find a perfect setting on the ground, but that will never end up being the proper tune for flight. And again, I'm talking about 2 stroke gas engines here.

For finding the right props to try, every manufacturer should have at least a few different suggested props for each engine. They should send the info with the engine. If not, it should be on their website. If you go to the RCGF site, they have that info in the specs listed for each engine. That'll point you in the right direction.

On my 26BM I used a 18x6 3D prop on my Edge 540 and it worked wonderfully. The 18x8 should work well on it also. You're gonna like that motor. Runs great and tunes as expected.

ahicks

My Feedback: (2)

mach2, I agree you don't need a tach to get a good tune. My point was more from a prop selection standpoint, and the fact I think everyone should at elast have access to a tach.

Finding a prop that puts the engine on it's torque curve with no tach is tough. Much tougher than it needs to be.

Picking a prop using nothing but the manf's suggested prop list is kinda like throwing darts at a dartboard. Some have quite a range.

My point regarding too small a prop on a DLE 20 was an example of what can happen when picking a prop "by ear". Especially when we know a prop that's going to allow about 8500 on the ground generally works best. Most of us are going to need a tach to hear/remind us what 8500 sounds like (vs. 10k+)....

If we were talking about a glow engine it might be a little different?

balsa1

Hi guys I hear what your saying but you have to develop that ear in 61 years in the hobby I'm 70 now and spent many years in a machine shop so the ears are not what they use to be. also in all that time I have only owned 3 gas motors and I of those never run so I'll use a tac. for at least for a while
one of the reasons for wanting as much info as possible is that these motors take props that cost a lot more than most of the nitro ones and while I have drawers full of those not many for gassers I know that will change over time I really thank you guys for the help Les

mach2

My Feedback: (5)

While I'm not saying you're wrong, I respectfully disagree with you that choosing a prop from the manufacturer's list is like throwing darts at a dart board. If we know the range of props recommended for that engine, and we know the airframe we are using in conjunction with our flying style we can make an educated guess at what props we should try out.

While I do use my ear to determine how a prop is performing, I also use the flight characteristics to determine prop performance.

Lets see if we can find a middle ground to agree on. As i've said, I don't find a hand held tach to be useful for tuning or finding an appropriate prop. I do however feel that an onboard tach can confirm what my ears and the flight characteristics are telling me. So, in my humble opinion, an onboard tach is really the only truly useful type of tach when getting an engine's tune and prop dialed in.

What do you think about that?

Jeremy

balsa1

Hi are you saying that the onboard tac will hold the highest reading if so that is great as I thought one had to have a radio that had shoot can't remember the word darn stroke that would be great Les

ahicks

My Feedback: (2)

Yes, not sure what kind of on board tach you are referring to either. Telemetry based, or one of the ones made by Rcexl?

Anything that can read rpm is a tach to me. I'd agree to anything that can confirm ground rpm is within a reasonable range. How that's done is a moot point here.

balsa1

Hi the ones made by Rcexl thanks Les

Captmicom

Hello Gang,

"DO NOT USE AN RcExl TACH ON THE NEW PEGASUS 4.8v to 8.4v CDI SYSTEM FROM RCGF" It will short out the new RCGF CDI. You will need to use a Pegasus brand tach in order for the CDI to run properly.

B-Squared

I'm sure this has been discussed before...is it OK to run a LiFe battery for the ignition modules. I noticed the other day the one I have for my 60cc is rated 4.8 a 6.0 v.

Captmicom

Hi B-Squared...

Well all I can tell you is the experiences friends and I have had. A new 6.6v LiFe packs most likely will make the older 4.8 to 6v CDI sputter and miss while running until the Batt drains down enough to stop over driving the power circuit. 6.6v to about 6.8v is about the top of the circuit in the older CDIs. Now is this a hard and fast rule? Not always but I would watch and see if it causes you problems.

mach2

My Feedback: (5)

I can't say what will or will not happen with 100% certainty, but I can say that I've used 6.6v LiFe batteries to power all of my DLE and RCGF ignitions with no issues whatsoever. I've not yet using any of the newer ignitions that are rated up to 8.4v.

Jeremy

Lifer

My Feedback: (1)

There is also an inline diode you can use that will drop the voltage to about 5.5 volts.

ahicks

My Feedback: (2)

I started running the diode on everything LiFe as I converted to them, but I forgot to install it on one and gradually "forgot" to put them in the circuit since. Have several of the old style modules and haven't cooked one yet. Not going to endorse the practice for everyone though. I'll smoke one of mine for sure if I did that....

rt3232

My Feedback: (6)

Hi Guys been following along on this latest item I have 3 engines running all of last season on 6.6 V life batts with no problems, about 2 hrs. on each.

cheers Bob T

mach2

My Feedback: (5)

Now that you guys brought it up, I forgot to reiterate the fact that I normally use the Tech-Aero IBEC which regulates the voltage. You can select the voltage to 5v, 5.3v, 6.1v or 6.6v via the jumper. I always had it at 5v since it doesn't need any more than that, and anything more doesn't help any. That said, with my RCGF 60cc I'm running a Redwing Red powerbox (has a CDI output/kill switch) and that particular model doesn't drop the voltage the way I have it set up. I don't have much time on it (probably a gallon or so) but I haven't run into any issues on 6.6v yet.

rt3232

My Feedback: (6)

Hay Joe / Captmicom

Can you give me the dim, plug cap to plug cap as I am thinking of putting this engine in a 1/4 Super Cub

Cheers Bob T

Jim Cattanach

Can anyone tell me where I can get a replacement bearing set in Europe, for an RCGF 20cc engine?

w8ye

My Feedback: (16)

Take the engine apart and measure the bearings and seal. Then order from a EU source?

Jim Cattanach

Thanks. I stripped the engine this morning & went to a local bearing shop with the old bearings. They supplied two new ones for only 5 Euros. Engine up & running by lunchtime.

w8ye

My Feedback: (16)

Good job, +1

balsa1

Hi captmicom do you have the Pegasus tac's or know were to obtain thanks Les

balsa1

Say what of the 10 or 15 's would you go with on a quaker 84 in I use to fly on 48 fourstroke I am kind of leaning to the 15 I think might be more versital but not sure the old 48 was not a real barn burner but I started a new one and as I like to just poop around I'm kind of up in the air thanks Les