Jump to content

repitch prop?


markmn

Recommended Posts

Now that the warm weather is here I can easily hit redline. Climbing tonight at olmost 700fpm and still maintaining 5500rpm. Static rpm is still slightly below 5000. The sensenich prop can easily be adjusted for pitch.

 

120kts was approx 5250 rpm when it was cold. now it takes 5500 to maintain 120. The engine is noticeably nicer and quieter at 5250rpm.

 

thaughts?

 

Mark

Link to comment
Share on other sites

Hi Mark,

 

I do mean 5500 rpm WOT flat and level at full throttle. I have a Tecnam at my field and that is what we did with his. Plus I bet you didn't know I was a Tecnam Service Center. Tecnam called me last month. You are looking to achieve the best all around performance and fuel economy from a fixed setting and be good for the engine at the same time..

Link to comment
Share on other sites

Roger,

 

Just want to be sure, You mean 5500rpm, full throttle strait and level flight?

Remember I have the tecnam p2008 if that makes a difference.

 

mark

 

You want to be around 4950 on the ground WOT. It's impossible to get it right on the ground, but this is a good benchmark and you won't over rev the engine in flight. Then after your test flight you can fine tune ii and know exactly where you are at to achive straight and level.

Link to comment
Share on other sites

Hi Dave,

 

I always tell people to set there 5500 rpm WOT at their normal cruise altitude. You just have to pick a spot and can't always adjust it. Some people fly out of sea level and cruise at 1000' AGL and some fly out of 7000' fields and cruise at 8000'-9000' cruise altitude. The pitch on the prop will be different.

Link to comment
Share on other sites

Roger,

 

Im in minnesota but when i get out there i will stop in. Want you to know i appreciate you always answering so promptly.

 

Flew to reedsberg WI this morning with my three year old son for a fly in breakfast. About 350mn round trip. A great time. Have about 120hrs on the P2008 so far this year.

 

Mark

Link to comment
Share on other sites

Hi Mark,

 

Actually I'm glad I can help and it feels good when it all works out. It's just a way for me to give back.

 

You need to hop in that plane with your wife and come to the page, AZ fly-In in Oct. It's a don't miss. There should be 2 other Tecnams there this year.

Link to comment
Share on other sites

  • 1 month later...

The maximum RPM I ever got from my Rotax 912 is 4920 in level flight with flaps à -12. It was adjusted by a guy who came from FD Ukraine. I am happy with the performance I get (on amphibious floats) but I have been told this is not good for the engine. Should I modify the pitch to get the recommended max RPM

Link to comment
Share on other sites

The maximum RPM I ever got from my Rotax 912 is 4920 in level flight with flaps à -12. It was adjusted by a guy who came from FD Ukraine. I am happy with the performance I get (on amphibious floats) but I have been told this is not good for the engine. Should I modify the pitch to get the recommended max RPM

 

 

Yes!!!

 

Ever thought about carbon fiber amphib's?

 

1430's amphibious complete weighing under 200 pounds. Lets see fiberglass or aluminum do that.

Link to comment
Share on other sites

Hi Floats,

 

I'm with Tad. Don't cause long term damage.

Sad to say the guy from the Ukraine didn't no what he was talking about.

 

Absolutely adjust your prop as that really low overloaded rpm will cause problems. You should see at least 5500 rpm at`WOT when you are flat and level. If you have a heavy plane and need a little better performance in climb with the floats and being heavy then set it up to 5600-5650 rpm WOT flat and level.

 

 

 

p.s.

Hi Tad,

 

Guess you had those few extra beers after all. Your better here and helping people.

Link to comment
Share on other sites

  • 3 weeks later...

Hi Floats,

 

It means Wide Open Throttle (WOT). You want to see what your WOT is at your normal cruise altitude. If you have an in flight adjustable prop then it isn't a big worry, but if it is ground adjustable then the planes that have wheels should shoot for 5500-5575 is a real sweat spot to be in. If you have floats and a heavier plane then you may want to be around 5600-5650 for the extra climb capability. Yes you will loose a little on the top end, but not a lot.

Link to comment
Share on other sites

  • 2 months later...

I cobbled together a simple tool that easily and accurately measures prop angle. It uses a Igaging digital protractor from Amazon $32. http://www.amazon.com/iGaging-Digital-Magnetic-Level-Protractor/dp/B002LL0BIC/ref=sr_1_11?ie=UTF8&qid=1321069765&sr=8-11. The measurement results are repeatable within .10 of a degree.

 

 

post-391-0-13914400-1321069583_thumb.jpgpost-391-0-08243400-1321069598_thumb.jpgpost-391-0-62986900-1321069613_thumb.jpg

 

Briefly, here is the process:

 

Set the prop blade to be measured to a horizonal position.

 

Create the tool:

- Epoxy a spirit level (Harbor Freight, $1) to the top of a wooden block approximately 5x5 inches.

- Pick the place on the prop to be measured (about 8 inches from the tip) and holding the block horizontal with the spirit level and behind the prop, mark three points on the front of the block, two above the prop and one below.

- Install three nylon spacers with bolts at these points. These will be the guides to slide the device onto each blade in the same position in order to get consistent readings.

- Mount a steel angle bracket on the back of the block. Attache the magnetic digital protractor.

- Hold the inside edge of the block flush to the back of the prop with a bungee cord.

- Take the measurment.

 

 

Roger Kuhn

Link to comment
Share on other sites

Roger K., your pitch fixture looks good. Form follows function and many of us have come up with similar fixtures for the same reason you developed yours; to consistently set the pitch. It takes some extra work to make a fixture but next time you need to check your pitch, you'll know that you'll have an accurate measurement.

Link to comment
Share on other sites

  • 8 months later...

post-124-0-02546800-1342826370_thumb.jpg

 

New CTLS, 25 hours now, Sensenich prop... WOT straight and level with -6 flaps was 5300 RPM. When checking prop pitch it was found that the 3 blades had a variance of 2 full degrees from coarsest blade to flattest blade. Reduced prop coarseness to lowest of the 3 then reset other 2 blades. All 3 blades within 1/10th degree using electronic pitch tool. WOT straight and level with -6 flaps now 5600 RPM. Engine is smoother, climb performance is now 1100 FPM (at sea level) with 15 degrees flaps and 900+ with 0 degrees flaps. Full throttle speed increased about 5 KTS oil temps in climb now cooler too! Prop pitch does have a big impact on performance to be sure.

 

PS, I bought this tool at aircraft spruce for 95.00. Looks like based on the pic from the previous post that there is about a $60.00 premium for the little plastic mount! I like the Amazon price better (oh well...next time!)

Link to comment
Share on other sites

Just finished a test flight after prop pitch adjustment...

 

Before: WOT RPM was ~5250 at 6000' DA (more or less my usual cruising altitude). At 5k RPM, I was making ~110kt at -6° flaps with ~5.4 GPH fuel consumption. Coarsest to finest blade was about 0.5° off.

 

Flattened pitch by about 1° and made them all agree to within 0.1°.

 

After: WOT RPM = 5550, 5k RPM at -6° flaps now gives ~115kt and ~5.0 GPH. Takeoff and climb also seem "zippier," although I didn't do any accurate before/after measurements.

 

I'm impressed with the improvement with such a seemingly small change.

 

-Russ

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...