Tracking a Prop

[Runtoeat]

Does anyone have a simple method to statically track a propeller?  I'm thinking of just removing my upper spark plugs to make the prop easy to turn and have a pointer on a stand which is in close proximity to the prop tips and indicates how far the prop tips are as they pass by it.

[Jacques]

Hi Dick,

you don't need to remove the plugs.

Put the parking brake and install a block, tool box or anything high enough to reach the prop tip.

when turning s l o w l y , bring the tip down vertically and approch the 'block' almost toughing the tip

when your position the 2 other tips, you want them at the same distance when at the same spot

 

that's my method...

 

just had a look on Utube  and found that

 

 

looks pretty much like what I do

[Roger Lee]

Hi Dick,

 

It is easy to do. Give me a call. The way our props fit I would be surprised if you had an out of track prop that made any difference.

[Runtoeat]

Hi Jacques, thanks for that video link. 

 

Hi Roger, I've got a few other questions for you.  I'll give you a call.

[Roger Lee]

I'm in a Rotax update class today and tomorrow. Call in the evening or leave a message where I can call. I did get your message, but it was late when I got back to the hotel yesterday and really late your time. I may try in the morning.

[Skywalker]

Roger, i am wondering if you can explain the variables in how the ctls prop can be adjusted for various pitches that would affect cruise ,climb. ,or max speed..I believe my ctls ,which was purchased From Fla. had the prop adjusted.I have to fly with throttle at firewall to get 5400 rpm 110 knots and 6.4 gph.The plane and engine are perfect no problems new hoses and the engine is smooth and starts with a flick of the key.i thought I saw an adjustment reference to17 degree plus but don't know if that is accurate. Would you mind giving me your expert analysis and anyone else who has an opinion chime in.I would think this to be an important issue since we are all interested in max performance measured by efficiency.I would like to gain max speed without jeopardizing the engine or completely losing climb, which is excellent.Also seems like high gas consumption for 110 kts.

[Ed Cesnalis]

You can gain max speed while improving climb and economy.  Your pitch is currently too coarse and you are unable to realize the highest power settings.

 

Your prop can only be set to one pitch so you need to pick an altitude for optimization.  7,500' is a good target because that is where your best performance is.  Out West 10,000 or higher might be better.  I advise limiting the adjustment to achieve 5,500RPM at your target altitude, I bet Roger might advise a little flatter yet.  To optimize for take off and climb performance you would want to achieve 5,800 rpm at your target take off altitude.  Optimizing for cruise will still give you improved climb so that's what almost everyone does.

[Roger Lee]

Hi Skywalker,

 

Ed is right. You are a little over pitched. Since we have a ground adjustable prop we need to pick an rpm that will fit our engine and aircraft performance needs and  of course our personal needs. 5400 rpm with WOT in flat and level flight is too course for the normal aircraft use. You are loosing climb, fuel and speed, not to mention higher temps. Over pitching Rotax engines (WOT rpms of 5200 and less) from about mid 2006 and back has caused cracks on the top of the crankcases. Cases after that time period has been redesigned. 

 

If I lived and flew as high as Ed does or higher like Leadville, CO I would make it a lot flatter because of the extreme altitudes and power loss due to those altitudes.

 

So you need to set your prop WOT rpm for your average altitude. If you are like ED and fly over 10K the majority of the time then that is what you need to take into consideration. If you live at sea level and never get over 5K then that is a point to consider.

 

So a good target WOT rpm at your average altitude would be between 5600-5700 rpm at WOT. Setting this up in this general area will give you a good balance in climb, cruise and fuel economy. This will also allow you some better performance when you go above your average altitude.

 

My prop setup gets me right at 5650. I can out run any CT with a WOT setting of 5400-5500. I have done it many times. Since I tend to fly heavier than most on two up cross country's this gives me good performance at take off and climb during the flight. I can still take off over weight with a 10K+ DA. How much over 10K DA I don't know.

 

If you are at 5400 WOT rpm at your average altitude then flatten the pitch approximately 1 - 1.25 degrees. 

 

Some people have special needs so in some cases (i.e. a float plane) may want an even flatter pitch to maximize climb over cruise. Maybe someone that wants a very short takeoff plane. Aircraft weight and drag coefficient plays a part here too, but just keep it simple.

 

There is some leeway and there is no real specific spot, but best practices and many years of prop research on a Rotax puts the sweet spot around 5600-5700 rpm at WOT.

 

Of course we could have the best of all world if we were allowed an in flight adjustable prop, but like our attitudes and personality since we aren't perfect a balance between extremes is best. 

[Doug G.]

So, Roger. If you were planning a trip west over the mountains from the flatlands, would you re pitch just for that trip?

[Roger Lee]

Depends on the elevation I needed to clear and how much of it and so long as my WOT rpm was above 5500 to start with, probably not. If I was at or below 5500 at lower altitudes then yes I would. 

 

No one should be below 5500 rpm at WOT in flat and level flight. This is preached to death in Rotax schools.

You will however be well below that if you only get 5500 rpm WOT at lower altitudes and then climb high due to loss of power and torque that the engine can supply at those higher altitudes.

[Anticept]

 

 

 

Ugh, I hate the sound of mouth noise in sound recordings.