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Old 05-07-2006, 05:17 PM
  #3076  
gjeffers
 
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Ok, thanks bill, i have a 16x8 3blade mas, ill order the same prop only a 6 pitch and try that, till then ill leave it rich, i can still fly 8 min with reserve now and it turns 8000 so its really flyin with plenty of pull anyways(it is running great and trans is good also)
Old 05-07-2006, 05:49 PM
  #3077  
IronCross
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Hey Bill
Just FYI... I got a chance to get some flights in today with the 13X4 prop on the .56... It did show a little improvement over the 12X6.. The plane seemed to come off the ground a little easier and was a little more "positive" going over the top of the loops.. Not a whole lot but noticable.... I did notice however that it takes more throttle to cruise around etc. The whole flight was done at a higher rpm then with the 12X6.. One thing however, I can now hear the engine increas in rpm with the throttle advance through out the entire throttle range... With the smaller pitch it is performing as you said it would a few posts back...
Thanks again
IC
Old 05-07-2006, 06:16 PM
  #3078  
William Robison
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IC:

When you lower the pitch you automatically have to turn more rpm for the same airspeed. In your case the 6” pitch gave you around 40 mph at 10K rpm. With the 4” pitch at 12K you still are only +/- 35 mph. The change isn’t linear with the rpm, the lower pitch will have less slip when it approaches pitch speed.

And this is also pointing out that you need to be careful: you can get the rpm through the roof in a heartbeat.

But at least you got to see the effect of z lighter load on the throttle response.

Bill.
Old 05-07-2006, 10:14 PM
  #3079  
jason35
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[]I have an saito 180 on an extra 300 and want to know if a person can put a flex pipe type exaust with pressure fitting on this engine and it perform ok? Thank you! Jason
Old 05-07-2006, 10:32 PM
  #3080  
loughbd
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Default RE: Welcome to Club SAITO !

ALL fuel is hygroscopic. Methanol is an alcohol and alcohols are hygroscopic.
Old 05-07-2006, 10:35 PM
  #3081  
IronCross
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ORIGINAL: William Robison

IC:

When you lower the pitch you automatically have to turn more rpm for the same airspeed. In your case the 6” pitch gave you around 40 mph at 10K rpm. With the 4” pitch at 12K you still are only +/- 35 mph. The change isn’t linear with the rpm, the lower pitch will have less slip when it approaches pitch speed.

And this is also pointing out that you need to be careful: you can get the rpm through the roof in a heartbeat.

But at least you got to see the effect of z lighter load on the throttle response.

Bill.
It would seem that the 13X4 prop is more effiecient choice with this engine/plane combo then 12X6... Can I also asume that if I can not hear rpm change when I advance the throttle the last 30 percent or so that I do not have the best choice of props for the setup ?..
Old 05-07-2006, 10:43 PM
  #3082  
William Robison
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Default RE: Welcome to Club SAITO !

jason35:

There's no reason you could not use the flex pipe on your engine, but please don't forget to add a mounting bracket somewhere near the outlet end of the pipe. They tend to vibrate and break if not supported.

And I've added you as number 278 in the Club Saito list.

Bill.
Old 05-07-2006, 10:59 PM
  #3083  
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Bill,
All of the 1960s up gasoline 2 strokes use in the neighborhood of 2% oil to gas mixture. Why so much oil in the Saito 4 stroke fuel (18%) synthetic plus 4oz Castor? Are they made from different metal,run hotter, run cooler, much different piston/cylinder clearences?
Sarge
Old 05-07-2006, 11:59 PM
  #3084  
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Default RE: Welcome to Club SAITO !

That's because most of the big gasoline two cycle engines have roller bearing rods and my Zenoahs use more than 2% oil.
Old 05-08-2006, 12:03 AM
  #3085  
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Default RE: Welcome to Club SAITO !

Bill

I was toolin' around on Saturday minding my own business when I suddenly had to call "Dead Stick!!" and proceeded to recover back to the runway. On short finals I noticed that the engine was still running at idle (where I always place the stick when an engine fails) and got no end of ribbing from my mates for crying wolf just to get landing priority!!

I ran it up prior to shut down and all appeared okay so didn't think much more about it.

Well, when I checked over the machine and spun the engine over - no compression. It appeared that the inlet valve on my 82 was stuck wide open. I dropped the rocker hats off and fiddled with it awhile and finally got it to free up.

My questions Bill:

1. Will I have done any damage turning the motor over (by hand) with the valve fully extended into the combustion chamber?
2. Are sticking valves common on the Saito's?
3. Is there anything I might be doing wrong that might cause the problem?

I am running 10% nitro, 16% synth and 4% castor.

TC
Old 05-08-2006, 12:15 AM
  #3086  
William Robison
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IC:

It would seem that the 13X4 prop is more efficient choice with this engine/plane combo then 12X6... Can I also assume that if I can not hear rpm change when I advance the throttle the last 30 percent or so that I do not have the best choice of props for the setup ?..
“Most efficient” and “Best” prop could easily be either one. It depends on what you want the plane to do.

Let’s try a different analogy.

The 13x4 prop is like running your car in second gear. It gives you good response around town, you can easily zip around the police barricades and keep going even when the cop blows his whistle and tells you to pull over. Not a lot of top speed, but good response. You can feel every twitch of your foot on the accelerator, and the engine screams in response.

Then, when you need to outrun the police cars in pursuit you shift into high gear. That’s the 12x6. Not so much acceleration, but the higher gear lets the car go faster down the road. Running 85 mph down the highway at about 60% throttle, you see them getting closer and push your foot to the floor. No more speed, the engine is giving all it has, and you can’t go any faster. Well, the road’s going down hill, you’re up to 90. But then it’s uphill again and you drop to 80 mph.

When they get you pulled over just tell them you were conducting an important experiment, they’ll let you go. Sure they will. Haw.

So, the best, or most efficient prop, depends on how yu want to fly. If you want to haul buggy from a stop then the 4” pitch is better, more efficient at the lower air speeds, and gives better response to throttle input.

The 6” pitch puts you in high gear, not so good on acceleration and quick throttle, but better top speed and fuel economy.

Bill.
Old 05-08-2006, 12:38 AM
  #3087  
William Robison
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Sarge:

The gasoline two strokes are engineered a little differently from our ordinary glow engines.

The gas engines are usually weed-eater or chain saw engines, either converted or using the same type construction. What you see when you open one up is a roller bearing in the big end of the con rod, and often a roller bearing at the piston end as well. The roller bearings need much less oil than our plain or bushed rod bearings do.

Some model engines have been made with roller bearings in the con rod, and these engines run happily on a much lower oil content than normal glow fuels have. Just for one example, the Technopower radials have a maximum allowable oil content of 5%, and the maker recommends running them on 2% for best results.

Another factor in our model engines is cooling. The excess oil carries a lot of heat out of the cylinder This is largely down played by advocates of synthetic oil, as castor oil is much better at carrying the heat out, the synthetic tends to burn and add heat rather than taking it out.

Many glow engines could be converted to roller bearing, and afterwards would probably run well on the lower oil content, but you’d still have to be wary of overheating. Don’t try this on a Saito, they still have plain bearings on the cam shaft.

One thing in favor of lower oil content is the added flight time with the same size tank – cutting the oil from 20% to 10% would give you another 10% of fuel to burn.

Bill.
Old 05-08-2006, 12:54 AM
  #3088  
William Robison
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TC:

I will assume the prop was wind milling on your approach, and the engine really wasn’t running.

1. Will I have done any damage turning the motor over (by hand) with the valve fully extended into the combustion chamber?
Very few Saito engines will allow the piston to hit the valve. I’ve even had one break a spring clip and drop the valve, the piston hit it so lightly that it didn’t even bend the valve. Just a new clip and it was running again.

2. Are sticking valves common on the Saito's?
A stuck inlet valve is all but unheard of on a Saito, exhaust valves after a lot of time with really high castor content have been known to gum the stems and stick. But not with 4% castor in the mix.

3. Is there anything I might be doing wrong that might cause the problem?
The only thing that comes to mind is the possibility of over speeding the engine to the point of valve float, and the push rod bouncing out of its seat holding the valve open. But you said you were just “Tooling around.”

I am running 10% nitro, 16% synth and 4% castor.
That’s fine, stay with it.

Bill.
Old 05-08-2006, 01:34 AM
  #3089  
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Default RE: Welcome to Club SAITO !


ORIGINAL: William Robison

TC:

I will assume the prop was wind milling on your approach, and the engine really wasn’t running.

1. Will I have done any damage turning the motor over (by hand) with the valve fully extended into the combustion chamber?
Very few Saito engines will allow the piston to hit the valve. I’ve even had one break a spring clip and drop the valve, the piston hit it so lightly that it didn’t even bend the valve. Just a new clip and it was running again.

2. Are sticking valves common on the Saito's?
A stuck inlet valve is all but unheard of on a Saito, exhaust valves after a lot of time with really high castor content have been known to gum the stems and stick. But not with 4% castor in the mix.

3. Is there anything I might be doing wrong that might cause the problem?
The only thing that comes to mind is the possibility of over speeding the engine to the point of valve float, and the push rod bouncing out of its seat holding the valve open. But you said you were just “Tooling around.”

I am running 10% nitro, 16% synth and 4% castor.
That’s fine, stay with it.

Bill.
Thanks Bill,

You are right, I was just tooling and not doing anything special - just circuits.

Interestingly enough, the engine hesitated badly in flight (hence the dead stick call) then apparently resumed running as I was descending as I actually taxied in under power after the roll out. It was not until the engine had cooled that I discoverd no compression and the stuck valve.

I am releived that I have not hurt the littel girl though.

I'll let you know if it re-occurs.

Kind regards,
TC
Old 05-08-2006, 07:00 AM
  #3090  
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Thanks for the tip. I just want to make sure it would work since I'm not using a pump for pressure. Thanks again! Jason
Old 05-08-2006, 09:06 AM
  #3091  
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Hey Bill
I understand your analogy and totaly agree with it ... As pertains to the engine and efficiency though it would appear to me that if I am not getting a response from the engine over say the last 30 percent of the throttle I am using the full potential of the setup thus inefficient... Could be that if it flew in a straight line long enough it would gradualy pick up speed but I have no way to verify that... I am not looking for either extremes in speed or torque... Just a happy engine/plane/prop combo..
Thanks
IC
Old 05-08-2006, 12:09 PM
  #3092  
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Iron Cross, I read your recent post about putting a 13 x 6 on the .56. I am flying the same engine and fuel, with 12 x 4 and 12 x 5, I thought the 13 x 6 would be too much, and it was! I put one on yesterday and retuned it, peak was only 9,400 RPM. I get better than 10,700 on 12 x 4 and 10,300 on 12 x 5. Am I doing something wrong, or was that a typo in your post? I'm 1000 RPM shy here.

This is on a profile funfly, I want lugging power, not speed. What RPM should I prop it for?

Cheers from the Barfly.

Old 05-08-2006, 03:23 PM
  #3093  
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Default RE: Welcome to Club SAITO !

IC:

It just depends totally on what you want the airplane to be, what you want it to do.

If you want good acceleration and a zippy plane, stay with the lower pitched prop. If you want the higher speed, use the 6” or higher pitch.

If you want it both zippy and fast, put a bigger engine in it.

Simple.

Bill.
Old 05-08-2006, 06:58 PM
  #3094  
IronCross
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Barfly
Sorry about that... That was a bad on my part.. I went with a 13X4, not a 13X6.. I was working on a .72 while talking about a .56... The .72 is turning a 13X6
Old 05-08-2006, 07:19 PM
  #3095  
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Bill
It appears I have upset the Saito engine god... I flew the .56 again and landed, taxied back to the pits and shut the engine down..While picking up the plane I bumped the prop and noticed it was freewheeling.... Thinking the prop was loose I remobed the spinner only to find the prop tight.. I put the spinner back on turned the engine over by hand a couple times and compression came back.. I flew it again and it was just fine till I got it in the pits shut it down and the prop was freewheeling again... Took it home, removed the valve covers and found the exaust valve sticking open...
I burn 15% Power Master and have never had a problem with it... Got to thinking... I have started lubing the rocker arms periodicaly as per discussions on this thread... I had been using Klotz with Castor but ran out.. Soooo being the genius I am
I used some STP I had sitting there... Just dripped some on the rocker arms etc... 4 flights later I have an exaust valve sticking..
Hmmmmm.... Apparently STP on a hot valve reacts differently the a quart of STP in a crankcase of oil...
It was no big problem to fix... A little WD40 and some 3 in 1 oil and I seem to have worked it right out..
I believe I have read you use ATF (with Dextron) for afteroil... Is this what you use to lube your rocker arms etc too ?...
Probably clean them up pretty good but I am not sure of the lubrication part...
Funny how these things work out... I put the 13X4 prop on concerened about over reving the engine and then I get the valve pronblem... Had me going for a bit there.. Thought for sure I had bent something for awhile..
Thanks
IC
Old 05-08-2006, 07:36 PM
  #3096  
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Default RE: Welcome to Club SAITO !

I use Corrosion X for afterrun oil and lubing the rockers plus some down the pushrod tube.
Old 05-08-2006, 07:55 PM
  #3097  
William Robison
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IC:

I have never used STP for anything on a model, and very seldom in a car. Just don't like it.

Dave's Corrosion X has a good reputation among the boat people, seems to do the job very sell.

But yes, mine is plain old automatic trnsmission oil, Dexron II or Dexron III specification.

Corrosion X is about $16 for a spray can, ATF iis less than $1 per quart. And I'm cheap.

Bill.
Old 05-08-2006, 08:18 PM
  #3098  
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Thanks guys... Haven't used the stuff myself for quite a while... Just had an old bottle handy.. My thinking wss being as thick as it is it would hang around the top end quite awhile... Gues it did, too long...
ATF sounds (price wise) like it might be my next try..
Thanks
IC
Old 05-08-2006, 09:29 PM
  #3099  
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ORIGINAL: IronCross
I believe I have read you use ATF (with Dextron) for afteroil... Is this what you use to lube your rocker arms etc too ?...
Probably clean them up pretty good but I am not sure of the lubrication part...
I use Mobil 1 synthetic motor oil (the viscosity isn't important) for manually lubing the moving bits and as an after-run oil. I've *never* had to replace bearings in an engine due to rust.

Either Mobil 1 works really well or I'm really lucky :-)

Actually, I can tell you it's not luck at all. I've currently got a piece of bare steel in my workshop that is providing interesting results as to the anti-rust abilities of model aircraft engine oils (ie: the amount of bearing protection).

Synthetic model engine oil provides only limited protection. The totally unprotected areas of the plate are now quite rusty and the area of my steel plate covered in Coolpower synthetic model-fuel oil is already showing pin*****s of rust below. The areas with castor oil and Mobil 1 remain unblemished so far.

I should repeat the test and include ATF I guess.
Old 05-08-2006, 09:44 PM
  #3100  
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Thick is bad when it comes to oil, it can't get to where it's needed.

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