vtach688

My Feedback: (8)

I have just complete the break in process on my OS 55AX (followed the instructions to the T). The power seemed good the first 1-5 flights and now seems lacking (vertical performance decreased). I used a 13x6 prop but tried a 12x8 with a reduction in performance. On first inspection i found the head had come loose and fixed that promptly. However, I get the same results of lower performance. Any ideas? Thanks in advance,


info:
Aerowork's Edge 540T, 10% Cool Power, #8 glow plug (yes i tried changing the plug), MA 13X6, 12X8.

w8ye

My Feedback: (16)

A 12 X 8 is going to have far less vertical performance than a 13 X 6

These props are too large for this engine anyway. The engine is probably getting hot

vtach688

My Feedback: (8)

good point, however, this is what is state in the manual prop range of 12x7-8 and 13x6-7.

w8ye

My Feedback: (16)

Those are props you would use on a 75AX

w8ye

My Feedback: (16)

If you want vertical try a 13-4

fredscz

My Feedback: (47)

All the 12x8 and 13x6 do is to keep the noise down by limiting the rpm of the engine.
I have had good luck with a 12x5 on my 55. Currently running an 11x6 on both that I'm using at present time. Out of sight verticle on either prop.
Fred

vtach688

My Feedback: (8)

good to know, what type of plane and how much does yours weigh

vtach688

My Feedback: (8)

thanks for the help, ill try a smaller prop maybe the 11s

liquid_TR

Try a 12x6 or 11x8 APC on it - see the difference.

rcdude7

My Feedback: (264)

If the head came loose, that is a sign your engine may have overheated. If you want to see what prop others are running on this engine, do a search in the tachometer forum. Enter prop sizes like 12X6 and 11X7 to perform the search, it seems to work better that way.

mk1spitfire

try 11x6,i don't think you will look back, good luck

vtach688

My Feedback: (8)

Yeah i rummaged around and found a couple of props from 11x6 to 12x8. My question is why would OS state the size props they do? Am i missing something...........[sm=72_72.gif]

w8ye

My Feedback: (16)

As someone has already said, they suggest the big props as it makes the engine quieter. Robs some of the power potential though.

All the new AX engines are spec'd this way

freakingfast

My Feedback: (3)

Yet another poor guy following the manual.


Try a Master Airscrew 11 X 7 (S-2 series!) or my second pick the APC 11X6 (Like so many have already stated), both props work well on most sport planes to trainers with stock or performance aftermarket muffler/pipes.

You should see 12500 to 12800 with a 11X6 APC using the stock muffler with baffle on 10 to 15% nitro.
Much less than this and it could have been hurt.

Oh, if it is coweled, is there a good air outlet? (Larger than the inlet) If not you can over heat it.

http://www.aero-works.net/old/planes...40t/index.html
If this is the plane, block off the inlet oposite the cylinder and if the muffler is blocking much of the exit (see pics @ bottom of page) you need to open up an outlet somewhere (bottom?).

The manual for the newer version edge tells you to make the outlet 3 times the size as the inlet and the new plane seem to have larger muffler area.

cymaz

Simple suggestion..... Have you leaned the motor out too much????

Jetdesign

My Feedback: (8)

I had the 55AX and had good results with a 13x5 and a 12x6 on 10% nitro. Keep the prop on the lighter side, don't run the engine lean, and you should be making more power after a few gallons of fuel. You can then try more prop and see what happens.

I think the mistake is that they tell you to use the prop you intend on flying with for break in. I've had 4 AX engines so far, and they all liked a lighter prop for break in. I tried using 'the prop I intended for flying the model' and either was not getting enough RPM, or it was taking too long to spool up. All times I switched to a lighter prop for the first two or three gallons and then back to the prop I wanted to use, and what an amazing difference!

DarZeelon

Vtach,


Those props in the manual, are probably an attempt by OS, to get their engine noise levels down; to make them turn 9,000 RPM and be usable in electric-only flying sites...

Props in the range of 10x8 to 11x7 (or 12.25x3.75W, or 12x4 for 3D), are the prop sizes to use... The manual is full of it, regarding the break-in technique also...

Read what the US dealers for OS tell you [link=http://osengines.com/faq/product-faq.html#q2]right here[/link]... Does the OS manual tell you that you shouldn't use all synthetic fuel???


An even better option for break-in, is to follow the procedure illustrated in [link=http://www.rcuniverse.com/forum/Tapered%2DBore_Engine_Break%2Din_%2D_Upgraded/m_1850473/tm.htm]this RCU thread[/link].

vtach688

My Feedback: (8)

no, i followed the manual to the T, sounds like not the best thing to do. DarZeelon, thanks for the heads up and links, it helps. Not to be negative towards any of you for your advice but how is one supposed to know which information is correct. The people on here seem to be more logical but does that mean throw the manual out the door? Is the manual just a ref. then. I am going to send my engine back for service and have them take a look. Thank you all for your help and suggestions.

DarZeelon

Quote:

ORIGINAL: vtach688

... Not to be negative towards any of you for your advice but how is one supposed to know which information is correct. The people on here seem to be more logical but does that mean throw the manual out the door?

Vtach,


Maybe not the whole manual... The parts detailing how to adjust the engine are quite usable, but even there you should take it with a pinch of salt...

As to why the break-in info in the manual isn't correct; please read the first post of the linked break-in thread...
You will no doubt understand what could result to some engines, if a break-in such as the one the manual details is adhered to...

Most OS engines are probably too loose to sustain catastrophic failure, but you can never be too careful...

vtach688

My Feedback: (8)

thanks for the heads up.

I went to the field this morning and tuned the idle and got it perfect. I tested the motor with the suggested, thanks you guys, 11x6 and 12x6 props. So far the motor performs better, more so with the 12x6. I didn't tach it yet as mine is due in the mail soon. However, just wanted to say thanks to all who replied. My fear was the motor got fried, but it seems ok, so far (Murphy you all know).

All in all good experience.

vtach688

My Feedback: (8)

one question on the break thread, when it says "...try to lean the engine carefully to maximum RPM. If the engine can hold maximum RPM without sagging, for 60 seconds straight..." Does the the "sagging" mean from idle or while attempting to achieve the max RPM? thanks

w8ye

My Feedback: (16)

while trying to maintain maximum rpm

Jetdesign

My Feedback: (8)

I think you will find that the 11x6 is too light especially once the engine is good and broken in. I get 12000+ rpm with an 11x6 on a .46AX. I'm glad the 12x6 is working out for now. Use that for a couple of gallons, then you can try a 13x5 for more pull if you want.

I have followed the AX manuals to a 'T' on 4 engines now and have zero complaints.

rcdude7

My Feedback: (264)

The "sagging" is the RPM starting to decay, ususally from lean mixture/overheating. The remedy is to richen the needle a few clicks. A sagging engine that gets no immediate attention will have a reduced lifespan.

DarZeelon

Quote:

ORIGINAL: vtach688

One question on the break thread; when it says "...try to lean the engine carefully to maximum RPM. If the engine can hold maximum RPM without sagging, for 60 seconds straight..." Does the the "sagging" mean from idle or while attempting to achieve the max RPM? thanks

Vtach,


As Jim (w8ye) and rcdude7 wrote; 'sagging' in 'R/C jive' implies a condition where the engine begins to lose RPM, without the throttle closing.

It happens due to detonation; usually from overheating and too lean a mixture, but in the case of the break-in 'end-check', it could be a result of improperly mated parts still rubbing together strongly... creating more heat, like when you rub your hands together...

When two mutually smoothed surfaces rub together, in the presence of lubrication, very little heat will result.

When two surfaces that still have minute 'ridges' and 'valleys, 'peaks' and 'dips' rub together, even in the presence of lubrication, a great deal of heat will result...
In an engine, overheated parts will cause pre-ignition and detonation, which give you 'fair warning', by first causing the engine to 'sag'...

Don't ignore this warning, lest be bitten by the burnt engine bug...