Nogyro

My Feedback: (10)

Guys,

I was testing props AGAIN on my RC Ignition G62/WH 28% and here are some figures I came up with. The G62 is one of Ralph Lite conversions, B&B muffler. Running Mobil Racing 2T @ 50:1, 87 octane gas. I've got almost 21 gallons through it, and 62 hrs. run time. Temps were 50 degrees, maybe 60% humidity, at 530 ASL. Props were switched out between flights, no needle tweaking, just changed props, warmed up engine, and took rpm reading..........

Mejzlik 23x8.................6810

Mejzlik 22x10...............7600

3W 22x10....................6930

NX 22x10....................6600

In flight, the engine increased rpms the last 3 or 4 clicks of throttle to WOT, except the NX 22x10. I believe it was just putting too much of a load on the G62 to let it increase any futher...

Zippi

My Feedback: (10)

Nogyro,

You need to tweak the needles on each prop and I think you'll see a better rpm reading on each prop.

Nogyro

My Feedback: (10)

Maybe a few r's left in there, but I flew it on each prop, and the engine sounded gooooooooooooooooood.

I'm not one to get every last rpm out of an engine.......

shakeelsid

Thats an interesting reading for mejzlik 22-10, how did the flight performance differ between each prop?

pe reivers

Thanks for posting.
Tests like this are great for me so I can check out the prop constants in my prop power calculator

pe reivers

The Mejzlik 22x10 seems out of whack a bit. Are you sure it turned 7600 and not 7200? Even then the engine makes a jump in power as if getting "on the pipe"

rmh

Maybe a different vintage 22x10?
We ran a lot of new pipe tests last week on 22x8/22x10 -- some other brands etc., on a ZDZ50NG. -7200 was the typical easily repeatable reading on the 22x10 Mejzlic.
The difference in header lengths to get best power on 22x8 to 22x10 mejzlic? -4 inches-

In switching to ZDZ40RE engine - the same pipe lengths which produced extremely high revs on Mejzlic 22x8- would not even work with the Mejzlic 22x10- again way off
we have a total of three zdz50s and three zdz 40s which have been run /tested - recorded
the loads of the various props is pretty predictable now . The engines do vary -a little but just as onewould expect with different wear. We were looking at pipe length to rpm -and this remains about the same irrespective of engine used

Rcpilot

My Feedback: (78)

I'm pulling better numbers on the 3W and NX props. I wonder why? Everyone of my G-62 engines will turn just about any 22-10 over 7000RPM. The Bambula 22-10 is the only one it can't turn that hard. I think my RPM was down in the low 6000 range with that prop--might have even been someting like 5800RPM ? [sm=71_71.gif] Can't remember for sure because it's been a few years.

My engines are newer than yours, but you most certainly don't have a worn out G-62 at only 21 gallons. Kinda wish mine had that much fuel through it. One of mine is just getting into it's 8th or 9th gallon and she's still spittin' out a tiny bit of goo. I don't know if it's my 1/2 synthetic and 1/2 dino oil or if the engine just isn't finished breaking in yet. I'm considering running a gallon of synthetic to see if that stops the black goo, but I don't want to do that if it's not broke in yet.

Has anyone checked consistancy between the NX props? I've had 3 different 3W 22-10 props sitting next to each other and all three were different. Different lengths on all of them and one had noticabley more pitch--just looking at it with my eye. Either that or the wood was wet when they milled it and it warped on the way to the dealer. I dunno why, but they were all different.

I've never compared two NX props side by side.

Nogyro

My Feedback: (10)

I wondered about the Mejzlik 22x10 myself. The tach was read right, 7600 it was. This is an old prop though, and I wonder if they've changed the shape a bit. I just checked my records, and I purchased the Mej. 22x10 on 8/31/01. This is the same prop I ran on my old G62/Giant Stinger combo, and my records showed 7700 rpm on that one..... The Mej 23x8, and NX are all less than a year old. Don't know about the 3W 22x10, it's my buddies...

The Mejzlik 22x10 never sounded like it was coming up on pipe. Nice steady transition while flying, but I bet it unloaded to 8,000 in the air.....The Mejzlik 23x8 unloaded some also, but the NX 22x10 was very little. I didn't get a chance to fly the 3W prop. The sun was going down fast, and I had been pushing my luck as it was with winds at 15 to 20 mph and gusting. No problem flying, but landings sure were an event!

There might be a 100 rpm or so left in there by tweaking the needle a bit. I was just a bit lean earlier in the weak, and opened the HS needle 1/8 turn or so. When taching, the rpm would peak, drop maybe 50, then hold steady. The steady numbers are the one's I posted.

On the flight performance, the Mejzlik 22x10 had the fastest spool up time, good verticle, and best all around IMAC prop. When doing 3D, the acceleration out of a hover was a tad slower than the Mejzlik 23x8, but still very good. When doing rolling harriers, it takes 3 oe 4 clicks more throttle with the Mej 22x10 as compared to the 23x8. Funny, on harriers, I had more wing rock with the 23" prop vs. the 22" stuff. The NX 22x10 was the hardest to get the plane to slow down to land with. Probably because of the aggressive pitch, which is noted in the rpm's as compared to the 3w and Mejzlik 22x10's. The 23x8 took more rudder correction during IMAC maneuvers as compared to the 22' props. The Mej. 23x8 and NX 22x10 were very similar in overall level speed, with the Mejzlik 22x10 being the fastest. Which prop is best really comes down to the airframe it's on, and how you like to fly. You can't go wrong with any of them. IMO, the G62 "seemed" happier when turning higher revs......

Like Rcpilet pointed out, I wonder how much variance there is between props, especially the wood ones. I would think the carbon fiber ones would be more consistent.

Richard D Bahmann aka/Wrongway

My Feedback: (42)

Hey Guys,

Did some testing on my G-62 lite yesterday at the end of my 4 gallon 32-1 break in oil.

R/C Ignitions G-62 on a 11 inch DA 25mm drop Q header and 17 inch baffle in E-composites Pipe.

Vess 23A = 7950
Vess 22B = 7500
NX-23x8 = 7050

23A is preferred by far, the prop is quiet and pulls like a mule even in the low end. The NX never got a high enough rpm to get the pipe to go beyond the norm. Tach readins were taken at the end of each 10 minute flight without touching the needles.

http://www.youtube.com/watch?v=jps3cDMJnm4

http://www.youtube.com/watch?v=jbQcD9cYRDQ


Anyone out there using the Amsoil 100 to 1 on a G-62?

Thanks,

R

ryan@ddm

The G62 is a great engine, especially above 8K rpms. With a little porting of the stock cylinder, you'd be amazed at the untapped potential sitting there waiting to be had.

Kweasel

My Feedback: (29)

Model airplanes need more power below 8k rpm!

ryan@ddm

Let me clarify. With proper porting, you can modify the power curve to suit just about any application. What I was trying to say was that the G62 will rev far, far above 8K RPM if that is what is desired. It can also be ported to make significantly more power at lower RPM compared to stock.

Bottom line - a stock G62 (like all the other angle-plug Zenoah family of motors) is massively detuned and can see significant additional performance without any sacrifice in reliability.

Richard D Bahmann aka/Wrongway

My Feedback: (42)

Where would one find resources on how to port one of these engines?

Thanks.

Richard

RTK

My Feedback: (1)

Not where I usually fly, my prop rip is nothing like a crop duster taking off 30 feet from you, plus I enjoy the sound of a good ripping prop

ryan@ddm

There are numerous books etc on two-stroke tuning available. However, I'd recommend having an experienced porter do the work for you, as it is very easy to destroy your cylinder if you are not comfortable with what you are doing.

pe reivers

Do a search for the jennings two stroke tuning handbook. It is available on the web as PDF.
Bottom line is, that you have to match the time-area of the ports to the new lower rpm situation, and then the tuned pipe if you need more power. The G62 is tuned for 9000 rpm where it has a very wide sweet spot. However, there is a max indicated mean pressure, so available power will decrease with rpm, though torque ( IMP) may increase slightly.
BTW, decreasing port time-area is not easy. Material has to be added, or the cylinder lowered with subsequent correction of the squish zone and combustion chamber in the cylinder head. With a piston ported engine, lowering the cylinder also increases the time-area of the induction port, which is not what we want at all.

ryan@ddm

A simply modification for the G62 is to use a thinner cylinder gasket - like .005" - stock gasket is .020" - this usually brings the squish down from around .035" stock to about .020". Then, raise the roof of the exhaust port back up .015" or so to compensate for the lowering.

Better squish for more power, and no net change in exhaust timing, so top RPM's should increase slightly.

pe reivers

In my book, that reduces scavenge TA, keeps exhaust TA equal, increases blowdown and increases Induction TA, thus needing a longer intake duct. That makes the engine more "racy" and narrows the nice broad powerband of the 62, and that is not what (edit (RTK)) Kweasel meant.

ryan@ddm

Of course. As I noted earlier, the porting changes made to any engine are based on the desired end use. In land-based, high-load applications (250+ lb vehicle and rider), the noted changes to a G62 are simple and effective. For a particular prop, load, and flying style, the changes a G62 user would desire vary significantly.

My point in all of this remains - the G62 is a great engine

pe reivers

I totally agree.

Richard D Bahmann aka/Wrongway

My Feedback: (42)

Say Pe, have you ever accumulated enough data on the Vess props to add them into your calculator? I could run some RPM and thrust tests on the props that I have beyond what is posted above.

Richard

pe reivers

I have noted your data, and might be able to link them to the NX prop for reference. This would make the data reliable for about 60%. Quite low, but better than nothing. Now, if you could throw in Mejzlik data for say a 22x10 prop on the same canister, that would be great and lift confidence level to 90%.

RTK

My Feedback: (1)

Pe, I think my G62 would turn a mejz 22x10 on an abell muffler at 7200+. Next time I fly it I will tell you, (with atmospheric conditions) my memory really stinks I know it was over 7000 (I think) but don't know by how much. Not much help I know, but you do have the most accurate spread sheet calculator out there

BillS

Nogyro,

First time you have the exhaust off would you mind looking into the exhaust to see if there is a finger port at the top of the exhaust port.

Thanks.

Bill