Capt Jim

My Feedback: (168)

Has anyone tried this G-62 with a 24 X 8 prop combo?
I am currently flying a 28 pound 3rd scale Cub with the Zenoah G-62 and using a 22 X 10 prop. What I am thinking of is trying a longer heavier prop...say a 24 X 8 loading down the motor, with the idea that it will allow keeping the rev's up a bit higher while still keeping the nice scale flight speed quite slow. Also the flywheel effect would tend to keep things running while flying at low motor RPM's. At those prop prices, I want to get a consensus before just running out and buying one.
Thanks for your comments.

rcdude7

My Feedback: (264)

Capt, 24" is a large prop for the 62 as it prefers to spin up some. A 23X8 would probably be a better choice. This size is popular with the DA-50R crowd, so there are many mfgr making this prop now, menz, mejzlik, 3W, etc.

Pelle Gris

On my G-62 I normally use 24in props. They do not provide maximum power, but they do lower the noise and let the engine idle lower.
Here are my numbers. All with a large 3-chamber silencer.

MenzS 24x8: 6200rpm
MenzS 24x10: 5800rpm
MenzS 26x8: 5300rpm
MenzS 24x10:6700rpm, but with a tuned pipe.

At the moment I´m using a cut down 26x8 MenzS on a 1:3 Pitts S-1. 14mm (about 0,5in) taken of each tip. Idle around 1300rpm, top around 5600 rpm, and plenty of power for an 18lb plane for scale flying. And it´s also a very silent model with a pleasant sound.

For a big Cub a 24x8 or 26x8 should be OK I think.

do335a

I have a question for you guys with the G-62.

Mine is on a Giant Aeromaster bipe, which weighs 21.5 lbs. all up, dry. I've tried a NX 22-10 prop and also a Zinger 20-14 which I had sitting on my shelf. In each case, the engine tachs at about 5800 rpm at full throtttle (about 1 1/2 gallons through it from new).

The plane can barely get into the air. Once airborne, it's not lively or snappy at all. It has all the responsiveness of a bloated, beached whale. It flys very heavy. Max throttle with about a 200 foot take of run are the minimum to get it airborne.

Based on my experience, I can't believe that a G62 can run a 22 inch prop or that it can fly a 30+ pound plane like many people claim. There is no way this G62 will turn over 6,000 rpm on a 24-8 prop. It can't even hit 6,000 on a 22 inch prop. The plane cannot even do a loop at max throttle from level flight. You need a very fast dive first.

So here's the question. Given your experience, what's making this combination fly like a pig? Any suggested solutions to get some performance from this engine/plane combination?

Presently, in my opinion, the problems are that the G62 is a wimpy, gutless, overhyped engine and the plane is excessively heavy - by about 4 pounds. Am I wrong on this?

I weighed the engine, along with mount, prop and muffler. It checks in at a bloated 6.5 lbs.!!!

Pelle Gris

Depends a lot on the muffler you use. Just as an example here are the results recorded using different exhaust systems, and turning a MenzS 24x10.

Standard box type muffler. The one with the 3 slits in the side: about 4800-5000rpm
Toni Clark stainless steel muffler, wich is the one I use now: 5800rpm
No muffler: 6200rpm
Tuned pipe: 6600rpm

So you see that from one extreme to the other there is a difference of about 1800rpm which is a LOT on a 24" prop. My guess it that with a properly set-up can you will get similar results as running without muffler.

For reference my G-62 spins a MenzS 22x10 at about 6600rpm which is not much for this engine. A lot would be gained by using another exhaust system.

do335a

Yes, Pelle Gris.

You are quite right. The muffler used will have an effect. In my case, I'm using a Slimline wrap around Pitts, which is generally considered to be a fairly free flowing muffler and not very restrictive.

In any case, you are getting some very nice numbers.

The operator's manual suggests you should be best setting the engine to run about 7200 rpm on the ground with a 22-10 prop. I can achieve this only in my dreams. I'm at least 1,400 rpm less, which is significant. It's no wonder the plane can hardly get of the ground and is ready to fall out of the air at less than 1/2 throttle.

The manual lists the output with and APC prop. It's interesting to note that APC does not manufacture a 22-10 prop, not that I would ever use a plastic prop in that size. I've been hit in the face when a blade separated from another modeler's 10" plastic prop. They are an accident waiting to happen.

Pelle Gris

I don´t know the Slimline personally so my suggestion would be to try running the engine without muffler, and record the rpm. If you are not in the 6500-7000rpm range with a 22x10 I would suspect that there is something wrong with your engine. I´m sure you have already tweeked the needles for max rpm?
Actually I used an APC 22x10 on my G-62 when I first bought it. 7200-7400rpm as far as I remember, 7100 on an APC 24x8.
Later the 24x8 developed a 1cm long white "crack" across one blade, right near the hub, so now it has been retired...:-)

do335a

You are right. Best test at this point is on 22-10 with open exhaust for direct comparison.

It appears to me that this engine is a bit weak on output. We'll see and go from there. Perhaps another tweak of needles is in order too. That did bring me another 200 rpm. Nothing to write home about but at least it was a start. That puts it at about 6,000 now. Still not enough to comfortably fly the 21 lb. plane.

Thanks for the reminder on the needles.

I'm beginning to think that this engine would be a its best use if it were converted to chain saw use!!

Capt Jim

My Feedback: (168)

You are not burning Ethanol in it....are you? Ethanol in the gas is an issue. It burns 30% faster than gasoline and causes a significantly reduced power output. If you burn an ethanol gas mix in your car...as some gasoline stations are giving you...you will see a corresponding drop in your miles per gallon. Interesting, eh? Pay more, and get less...what a world.

There are a number of potential reasons for your G-62 to be seemingly down on power....fuel/oil mix, carb tuning, air bleeding into the carb/crankcase pulse port....etc. I would suggest that you look quite closely at your tuning. The G-62 is a well known, and very successful work horse of an engine, and you should see much better performance than what you are getting.
By the way, I fly my 22 pound GS Aeromaster very well with a G-45. Not gobs of power to spare, but from your dismal description, it will fly rings around your your plane. Not to brag, but rather to demonstrate that there is an issue with your motor.
You may be a bit timid about tuning the needles, and if that is so...try to have an experienced Zenoah friend tune it for you.
You and your G-62 will be well rewarded by your efforts.

do335a

Hi, Captain Jim.

I appreciate your insights.

My first consideration with the engine was indeed the fuel. It's been a long time since I've run gassers, as that was back in the day when I had several Quardas - 42 and 50. Then the fuel did not contain any alcohol. Presently, as a result of government fidling (they call it prudent legislation, but that's another topic), by their mandate, we have regular, with up to 10% alcohol, mid range with up to 5% alcohol and high octane with no alcohol. So since the start, I've been using the hight test, with no alcohol and followed the engine instruction manual by using a 25:1 gasil mix with a non-synthetic 2 stroke oil, intended to be used in air cooled engines - not outboards since that is different oil.

I would also comment that my weed whacker really likes my old glow fuel. When I mix about a 5% nitro into the gas, it really spools up and can take on anything up to about a tree sized trunk!! Now there's an idea for the Zenoah.

As for the GA, I was looking forward to installing my smoke oil tank and pump. However, I shelved that when I came out at 21.5 lbs and could hardly get off the ground. The best description is to say that it has a very heavy, ungainly feel to it. By contrast, my Sig CAP 231EX, with an OS 1.60FX being broken in, at about 12 lbs seemed light as a feather and flew aerobatics at about 1/4 to 1/3 throttle at most with the greatest of ease. Prop was a Master Airscrew 16-10 3 blade. Fuel was 5% nitro.

I'll do some tests this weekend with several props and open exhaust. I'll tweak the carb and go from there. Oh, one other thing. The engine starts great, especailly when cold. Two - three flips to prime, one with choke and one to start. Every time.

All help and suggestions are greatly appreciated since I am not familiar with Zenoah engines and there is nobody else in my immediate area running them.

Capt Jim

My Feedback: (168)

Just as a tuning tip.....beginning with pretty much rich needle settings.
Tweak the high needle for maximum RPM.
Then, go back and lean out the low needle until you begin to lose the quick transition from low rpm to high rpm....that loss of transition indicates that your low needle is just a bit too lean....go back and open it up a bit more. I generally make 1/4 turn adjustments on the high needle and 1/8 turn on the low needle. It may take longer to tune, but that way I dont miss the sweet spot.
The needles may interact a bit so after you have sorted it all out this way, you may want to go through the process again...rechecking the high, and then the low...especially if the needle changes were substantial.
It is a pain if the needles are facing the prop. I dont generally like to tweak a needle that close to the prop when it is running...however, I have done it...from behind of course, and only when there is no cowl and very good access and room for a relatively secure body position.
Be very careful, and best of luck.
jim

do335a

Well, guys.

thanks again for the suggestions.

Today was prop test day and here are my results:

Results after adjusting mixture:

Zinger 20 x 14 wood 6,300 RPM

Pro Zinger 20 x10 wood 7,800 RPM (this is a prop very much like Vess, NX, Bolly, et al. in shape, blade size and weight)

Master Airscrew Classic Series 20 x 10 carbon filled nylon 7,800 RPM (this prop has slightly greater weight than Pro Zinger and has paddle shaped blades)

Master Airscrew 22 x 10 wood 6,100 RPM (this is a prop very similar in weight and paddle blade and tip shape to Zinger wood)

Temperature was about 75 F with about 53% humidity.[/b]

Would have been nice to have a 20 x 8 as well, but that's life. Maybe next time.

So tomorrow will be flight test day. I think I'll start with the MA Classic since the bipe is a high drag airframe. The MA wood at only 6,100 does not really look much better than initial testing prior to adjusting mixture, where I got 5,800 on the NX 22x10 and Pro Zinger 22 x10.

I still think that a 24" prop is totally out of the question for a G-62 based on my limited experience, unless you're flying something like an old timer, which only needs about 2,500 rpm.

dragoonpvw

My Feedback: (7)

do335a
I think you have something off somewhere. My g-62 with a simple bennet or jtec muffler turns in the 6800 - 7000 range. I fly it now tuned at 6750. I run a xoar 22x10 . Here it is flying my 31.5 pound Byron Corsair. http://www.youtube.com/watch?v=XvRM5a5BUiM
as you see there is no problem with accelleration on take off, also you can see it pull a good size vertical after a run. Mine does all the manouvers with ease and weighs ten pounds more than yours. The only difference is drag. There is definitlely something wrong with your setup, check your carb and fuel supply. Then tune with the 22x10 or 8. If you are looking for aerobatics I might go with the 22x8 but the 20 inch props would seem a little small for me.
good luck
Paul

do335a

dragoonpvw,

I must agree. After watching your video - very nice - I feel the same way. Something must be off.

My first thoughts were that I should just chuck the engine instructions and treat it like any 2 stroke glow engine I've ever run. In fact, that's what I started doing when I ran the prop tests.

I installed the MA Classic 20-10 and richened up the main needle to back off from 7,800 rpm to about 7.400 rpm for a couple of flights. Subsequently, I tached the engine without any more adjustments on a similar day for weather and tached 7,800 rpm. The engine felt very strong and the plane's performance was good. Either my tach lied or the engine is showing improved results with more running. I suspect the latter is the case.

My policy with the G-62 has now changed: apply variable loads in the air and just run the snot out of it without any concern about break in. It'll either break in or just plain break.

raptorflyr

My Feedback: (20)

I've got a G62 with a slimline pitts muffler installed in a Lanier 33% Laser. It has never been weighed, but I would guess it is in the low 20's for weight. Although the plane is not a 3-D monster, it flies well with the 62. My engine is very new and it gets better every time I run it. I ran it on a bench and then put it away for several years (the Laser was a labor of love for years ) . When I first took it out, we had problems with power and consistency until we rebuilt the carb. The carb rebuild made a big difference. The kit from Horizon is cheap.

I've run a menz 22x10 and have settled on a TBM 23x8. Either prop gives plenty of pull.

I'm sure you've thought of the silly stuff like restrictions due to smaller fuel tubing. Do you have a free flowing vent in the tank? We had a guy with his first gasser that hooked the vent on the tank up to his smoke inlet on the muffler not realizing he didn't need pressure. That would have been an unfortunate end to a big comp-arf bird!

Worst case, maybe something is goofy with the engine itself such as the magneto. Horizon has great service and I'm sure they'd sort it out for you in short order!

Good luck.

Colin Gardner

I had my Z62 in a Giant aeromaster using a 22*10 prop which ran at about 7000rpm We fly at about 5000ft. The model was really the nicest I have ever had and performed excellently. One day complete radio failure and ora pro nobis. I wish I could get another one. However in the crash the crankshaft was knocked out of line. I took the engine to pieces put the crankshaft in a lathe and using a depth gauge realigned it and reassembled. Everything now seems fine, fuel being sucked up, spark etc but it will not go or at least it will but very reluctantly and with a lot of backfiring etc. I am now wondering whether it is possible that in realigning the crankshaft I might have altered the timing. The flywheel is set on the crankshaft with a woodruff key which unalterably sets the timing. I can't see how I can have moved it but has anyone had experience of this. I suppose that the very abrupt stop of the engine in the crash could just have caused the front part of the crankshaft to turn in the big end web where it is a press fit. Even if that has happened , how would you know how or where to reposition it to know that the timing is correct. I have fitted my other G62 in my very large own design Big Stik which is excellent but I may try a 23 or 24 size prop because it is so delightfully slow flying but will do practically anything that I ask of it. I will be most grateful for any observations that anyone may have regarding the timing etc.

JKOC59

[size=2]I have a ZIROLI 100" Stuka Ju 87 with 26 lbs and the zenoah G62 run very nice with 22x10 (6.500 rpm) and the flight is good, no fast but trust every time. The flight is good with 20x10 three blades (9.300 rpm), but with no the trust like the 22x10 two blades. I will try the 22x10 three blades and report to this list. I agree the 24 prop will not work for the 1/3 or 1/4 scales more than 26 lbs.

w8ye

My Feedback: (16)

I think the rpm sweet area for best power is around 7000

do335a

Well, guys, thanks to everyone for the comments and suggestions.

I's been a while and now the Giant Aeromaster is down for reconfiguration. Stripped off the fuselage covering and will change the shape and cowl to resemble a Pitts Python and then recover. So the G62 is presently just waiting.

However, the best solution was the idea to just fly the snot out of it with the attitude that either it will break in or it will break in. That has resulted in a much better, stronger performance. Here's a link to a short video of it on You Tube, running the smoke system and a wing walker. Previously, this sort of take off and flight could only be accomplished in my imagination:

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

Now that's the sort of results that I was expecting from this engine. Prop is the Master Airscrew black, paddle blade 20-10 fiber filled nylon model.

I suppose my GT80 will need an hour or so of bench time before it starts to perform too. Got it for a 33% H9 CAP 232

flygilmore

My G-62 is turning a ProZinger[:'(] @7500 with less than a gal. through it. It is well known that the 62 likes to rev. so anything over 7000+ is where it is most happy and efficient. Also, many people have stated that they have never seen a "worn out" 62-they all end up crashed before that happens so yes, the more it runs, the better it will get.

podo

My Feedback: (2)

Flygilmore, would you please state what size Pro Zinger,
Thanks,
Pete

crash55

22 x 10 will get you what you want most times.

1and a 1/4 turns on both needles to start and tune from there.

Once transition from idle to full rpm is achieved by tuning the low neddle (L) then focus on the high (H) needle.

I normally use a 30:1 oil mix a little extra never hurts for run in, after that I use 35:1 mineral based until you are happy with run in then go to a synthetic oil.

Remember these are agricultural engines for Chainsaw and Whipper Snipper use and are well suited to have the crap run out of them. Just keep an eye on the temp.

Suggestion here is to run it hard for a good 10 to 15 minutes air time and then rest it allowing to cool down, then go again. I would not worry about bench testing unless you wish to ensure everything runs well before mounting in your aircraft.

A regular check of the built in gauze filter in the carby is well worth doing and a rebuld kit ever few years helps too!

I have found this works well enough for me to use the G62 as an aircraft tug for gliding on a 22 x 10 or for Racing a 32 lbs model Spitfire 96in wingspan on a 19 x 14 prop and win the Adelaide Warbird class in 2003. and still place in 2005 and 2007.

Hope this helps.

Crash Carpenter
Adelaide
Australia

JKOC59

About my last post, I use a 20x10 in G62 STUKA JU87B2 ZIROLI 100" and run with 7500, no 9500 like I wrote. That`s MISTAKE. SORRY !!!

Antique

My Feedback: (4)

Good on ya, Crash...We have been racing STOCK G62s in 26 lb 100 inch AT6s for about 17 years...'
started with Zinger 22-10s, now run special APC race props...The exhaust is an 8 inch straight pipe...Most of the G62s unload to about 9000 in the air, verified by Eagle Tree..
I think the props are 19-14 or more...The T6s are not draggy bipes, but at 26 lbs they take off very well...
My own 1989 or so G62 flew a 30+ lb Noorduyn Norseman on floats for many years with a 24-8 prop and stock muffler with 2 pipes brazed in and the slits closed...Not too loud, not too restirictive...
I hav e 3
scratch built 20% oversize Andrews Aeromaster hanging in the ship, flown many years very well in Phoenix, altitude 1000 ASL...Always with a Zinger 22-10 and a loud muffler.
converted 62s weight only about 4 lbs..conversions are available here from some of the advetisers..They're DIY RC EXL ignitions...

microdon2

My Feedback: (47)

I picked up a Carden Extra (89") with a G62 a few months ago. The plane is a bit heavy, but supposed to be a great flier, and is great looking. The engine ran great, but it had a magneto and I didn't like having to use a starter. So I just did a converstion, replaceing the magneto with and Electronic Ignition. Today's the first time I've run it with the EI and then engine has no power! I did lean the high end and that seemed to help, but I didn't have a tach with me. I'm using a Xoar 22x10, which seems like a good prop, going by these posts. I have a Pitts style exhaust on it. I'm guessing I should be hitting around 7,000 RPM's. Should I just keep leaning the high end? (will bring a tach next tim4). Does this engine run better with a magneto vs the EI?

Thanks.