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New prop hub installation

dick seiders

Well Known Member
Received new hub,(SB from Sensinich) and installed a day or two ago. When I first installed prop last year I set pitch about 60% of full. Worked fine and climbed like (you know). Followed directions this time and set the prop for full pitch. WRONG!
Just took it up this am . Temp 34 degrees c light crosswind at 6 kts. It took forever to get airborne well anyway about 1000' and it climbed like a man older than me. I believe I was 2 mi. from the field by the time I arrived at 2000'msl. Landing was a treat as well as I could not slow it down, and crossed the fence at 77kts. instead of 55. I guess the point is I am going back to 60% of full before flying again. Just wanted to share this with all as I was quite surprised at the significance of the change in flying characteristics of the RV12 in this prop configuration. Anyone else have any prop stories? They may be helpful to those now building/flying that haven't yet ventured there.
Dick Seiders
 
But, tell us how fast was it once you got to cruise! I have been surprised at the LACK of prop pitch settings information on this forum. Are there figures someplace that gives one the information he needs to choose a pitch setting? What does Vans recommend?
 
Prop Pitch info...lots available

But, tell us how fast was it once you got to cruise! I have been surprised at the LACK of prop pitch settings information on this forum. Are there figures someplace that gives one the information he needs to choose a pitch setting? What does Vans recommend?

Hey Don,
There is no lack of discussion on the forum on prop pitch:

http://www.vansairforce.com/community/showthread.php?t=59682&highlight=prop+pitch
and:
http://www.vansairforce.com/community/showthread.php?t=62965&highlight=prop+pitch

are just two of many threads with past experience, results, pitch tool, speeds experienced, RVator article, and recommendations by the experts at Van's.

Bottom line -- you need to use a digital prop tool and set the adjustment in small (0.3?) increments, until optimized for your mission.

Tony
 
Use the production acceptance procedure

If an RV-12 bulder flys all of the prescribed flight tests documented in the P.A.P., it will lead them to an optimized prop. pitch.
 
Lots of interesting information, but I was looking for best approx. position to get good climb rate as well as top speed. Climb to me in the Hotlanta temps. we enjoy here is more importent than top speed. I am in the process of installing wheel pants to help with the speed. The rpms and climb rates mentioned lead me to believe my 60% of full pitch was a good place to be. I usually peaked at 5300 on climb at 75-80 kts with climb rates comparable to my (former) constant speed equipped RV6A, and when leveling off had to reduce throttle to hold the rpms to 5500 max. My speed at 5500 was only 114 kts at 3000 msl however and this am at full pitch made only 116. Of course I didn't fly long today as mentioned earlier as my max rpm was about 4700 on climb and about 4900 -5000 in level flight. That's not a good place to be.
Dick Seiders
 
Lots of interesting information, but I was looking for best approx. position to get good climb rate as well as top speed. Climb to me in the Hotlanta temps. we enjoy here is more importent than top speed. I am in the process of installing wheel pants to help with the speed. The rpms and climb rates mentioned lead me to believe my 60% of full pitch was a good place to be. I usually peaked at 5300 on climb at 75-80 kts with climb rates comparable to my (former) constant speed equipped RV6A, and when leveling off had to reduce throttle to hold the rpms to 5500 max. My speed at 5500 was only 114 kts at 3000 msl however and this am at full pitch made only 116. Of course I didn't fly long today as mentioned earlier as my max rpm was about 4700 on climb and about 4900 -5000 in level flight. That's not a good place to be.
Dick Seiders

Hi Dick,

It is hard to get the prop set to exactly the same position each time it is apart due to the very fine adjustment required to get the setting on the first blade and then getting the second blade the same with out moving the first blade again.

I have found that it is helpful to know from your experience what ground static RPM gives you the performance you desire. Here in Florida (flat and sea level) we like about 4900 RPM as a starting point. Van's, if I recall correctly suggests about 4980 RPM. Most of our people want to end up with just being able to make 5500 RPM at full throttle at 1000 feet and we usually end up trying three times to get it right.

Best regards,
Vern
 
setting the pitch

I just received my prop hub back last from the SB repairs last Friday. However, before sending it off, I checked my prior settings. I don't have the digital tool but do have a bubble version. Mine were both set at 21.5 degrees using the prop measuring tool that Tony T and others have described combined with a bubble protractor. When the hub came back, I simply reset them both to exactly 21.5 degrees again. Everything is perfect (static, climb, and full throttle cruise RPM).

Of course, others may have different settings to achieve the same result due to differences in tools and technique being used to measure and set the blades. However, the little "T" tool (as I call it) and bubble protractor have worked very well for me. Very reproducible.

Jeff
 
Thanks to all for the feedback. I will go for the angle checks. Is a tool necessary? Once assuring the prop is in a precise level horizontally can I not just check blade angle with a digital level?
Dick Seiders
 
Thanks to all for the feedback. I will go for the angle checks. Is a tool necessary? Once assuring the prop is in a precise level horizontally can I not just check blade angle with a digital level?
Dick Seiders

Hi Dick,

The tool in the following thread only take a few minutes to make from leftover material from the kit. It provides the way to have a firm three point contact on the blade so that you get the same reading each time allowing you to set one blade and check the other to be sure they are the same and know that your readings are both done exactly the same.

http://www.vansairforce.com/communit...ght=prop+pitch

You might also make a prop stand out of one of the 2 x 2 boards that came on the crates. I cut a slot in one end and then cut it to the right length so that the prop is level with the board under one end of the prop. Dead level is not as important as taking the reading the same way on each end. Use the board under the left hand blade at a fixed point under the tip of the prop, take the measurement on the right blade. Then flip the prop over and repeat. This allows one person to do the job even if adjustment is required.

Best regards,
Vern
 
Hey Vern,

Thanks for the post, but the link provided, came back with "The system cannot find the file specified."

Did you pull the plug on the link?
 
Tried a Warp Drive protractor on my prop today. Appeared to be about 4 degrees of total travel (19 to 23). Set it up at midpoint (21). Static run up at 4900. Climb out at 5050, At level off rpms moved to 5400. Back to drawing board.
Reset prop 1/2 degree further into pitch (20.5). Static run 4950. Climb out 5300. Rpm quickly moved to 5600m on nose level then ran into some wind shear (very bouncy) so throttled back to 5000, and engine sounded rather strange like maybe a fuel problem. Each time I gave it more throttle it was ok then reducing rpms resulted in more weird sounds .Headed back to runway rather quickly in case there was about to be a problem. A number of local airport advisors told me I was experiencing prop flutter which they defined as the prop unloaded (neither pulling nor pushing) on the gear box which creates the sound and a little vibration.
Any of you ever have it? At any rate I liked it so very little I reset the prop again, and getting a bit more aggressive moving the blades I discovered there is 5 degrees of total travel. I used my aiming point at number 3 mark on the hub (Sensenich recommendation) and wound up about 3.4 (which coincidentally is where it was before I changed the hub). In degrees that tranlated to 19.9 on the range of 18 to 23. (the blades can easily be set within 1/4 of 1 degree). I will post results of flight test planned for tomorrow.
Appreciate any feedback
Dick Seiders 120093
 
Dick,

In my experience it is important to get the two blades set to as close as possible to the same pitch. Using the little fixture I built and a digital level I can set my blades to within .1 degrees of each other. That will minimize vibration. As to the pitch angle that you want, it depends on whether you are looking for best climb performance or best speed at cruise. Your static runup at 4900 is a bit low - that would give you a real cruise prop. My advice is to come close to a static runup of around 4950 to 5000, with the blades set as close to the same pitch as you can get it. Then fly it for a while. You may need to adjust the pitch again after you get 20 or 30 hours on the engine.

When you are checking the WOT static RPM try to do it in a no wind condition. Any wind at all will affect the RPM you get.

As to the "noise" - not sure. Haven't heard it. How bad was the turbulence? Try the same test in calm conditions.

One last comment. I had a dynamic prop balance done, and it made a HUGE difference in vibration level. But first, get those blades set equally.

Best of luck to you - I find this "tweaking" phase enjoyable.

John
 
Test flight #1 today was with prop indexer set at 3.4. Static run was 5050 rpm. Climb out at 5350. Level off and quickly went to 5500. Speed 110 kts. I experienced 3 small burbles that were very short duration compared to flight the day before. When the burble occurred the rpm dropped from 4750 to 4700, and immediatly returned to 4750 when burble stopped. Still don't know what that is. Could be a very small amount of moisture in gas, or maybe the prop blades were not in sync. Don't know just guessing.THe burble occurred only one time before several weeks ago when during climb out I turned from rt crosswind to rt downwind. Wind speed was about 8 kts. Change in direction of wind on prop maybe created the burble? Yesterday the winds after climb out were very turbulent when the burbles occurred. Anyway back to the prop. For test flight two I reset the indexer to 3.7 by making a very small move to increase pitch. The entire movement of indexer is only about 1.5 increments. Static was 4950. Climb out at 5050. Temp on the ground 33C. When leveled off I could get 5800 wot. Temp at 3000 was 26C and my cruise at 5500 was 118 kts. No burbles occurred. That's the best cruise I've had thus far. Conclusion: I like the performance generally. I still prefer a little better climb out but I believe air density was around 3500 so that likely affected it significantly. I plan to fly it for a while at this setting. Later may try to tweak it a bit to the climb end, but maybe not. 118 kts true w/o wheel pants is pretty good. Comments appreciated. Thanks.
Dick Seiders 120093
 
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Dick,

The burble (shudder, hesitation or engine miss) sounds very similar to what I experienced and may have nothing to do with the prop adjustments you are making.

In fact, the momentary engine shudder with a gas smell in the cockpit that I experienced came on my flight just after a prop pitch adjustment. So far it has not recurred after draining all of the gas (I put it in the car) and added fresh gasoline from a high volume station. My problem may have been vapor (bubbles) in the fuel lines. Download the data from the Dynon, import the data into Excel and plot the RPMs, fuel pressure and fuel flow. Pressure oscillations and wild fuel flow changes not related to an RPM change could mean you have seen a problem similar to mine.

See my thread.... http://www.vansairforce.com/community/showthread.php?t=72330

As far as prop pitch goes, setting the prop using the index marks, the bubble protractor is not the way to go. I used the bubble protractor and found using a fisture and a digital level, the blades were close to 1 degree apart. See this thread.... http://www.vansairforce.com/community/showthread.php?t=64568&highlight=prop+adjustment+tool
 
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I agree with Marty....

... I don't think the hesitation is due to the prop. Why not try a test flight with some 100LL. Even if you don't like the idea of using 100LL full time, one tank won't hurt anything.

Your pitch setting sounds about right for now. Only change it if you find the blades do not match.

How is the vibration level? Do you feel any shaking in the stick? If you do, consider getting a dynamic prop balance. It made a huge difference in my airplane.

John
 
Engine burbles

I agree with Marty and BigJohn. The fuel is forming little bubbles (vapor) either in the fuel lines or in the carburetor bowl. The problem is most prevalent at full throttle on a hot day, especially during climb out on second takeoff when the engine (and fuel) is hot from the prior flight.
Joe Gores
 
Prop Hub

I have been adjusting, then flying the RV-12 with trial and error Sensenich ground-adjustable prop blade settings. I believe I now have the prop about where it should be. Here are the results of today's trial from KANK airport at 7525-ft msl, density altitude 9,800-ft:

Take off climb at 68-mph WOT showed 5,040 rpm (climb rate 650 fpm +)
Level flight WOT at 8.870-ft msl showed 5,550 rpm
Two 180-degree legs at 5,250 rpm showed showed
IAS 110/110
TAS 129/127
GPS 142/121

Will leave things as they are and check again from time to time.
 
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Big John, no vibration of any significance. I plan to have prop balanced after flying enough hrs to find that I am satisfied with the pitch. I think the burble may have been a combination of wind, change in throttle setting, and maybe the prop blades being unmatched a bit. After last set of pitch I could not reproduce the burble using the same remaining fuel I've had in the tank for all four test flights.

John F., wow on the TAS. I would'nt change anything either.
Dick Seiders
 
Climb Suggestion

Take off climb at 68-mph WOT showed 5,040 rpm (climb rate 650 fpm +)

John,

I'm not trying to pick nits, but you might want to review Rotax SL 912-016 page 4 section 3.1.2 step 2. They recommend, among other things, that to help prevent preignition/detonation to not climb with WOT at less than 5200 RPM.

After reading that Service Letter I do what I need to clear the ground and once all obstacles are cleared I climb at just above 5200, which tends to give me about 82 knots and 800 - 1000 FPM (solo).
 
Climb and Hub setting

No, Steve, that 68mph at 5,050 is not the max available or full effort. It is a data point to determine hub adjustment recommended by Roger Lee of the Tucson Rotax Service Center....different rates of climb will produce different rpm max figures. They recommend testing performance by setting the rate of climb at 68mph and then insure that you have at least 5,000 rpm. Other than that there is no significance to that rpm figure. The second check data point they recommend is WOT in level cruise at what ever altitude you usually fly to insure that you can get 5500.
 
John,

I'm not trying to pick nits, but you might want to review Rotax SL 912-016 page 4 section 3.1.2 step 2. They recommend, among other things, that to help prevent preignition/detonation to not climb with WOT at less than 5200 RPM.

After reading that Service Letter I do what I need to clear the ground and once all obstacles are cleared I climb at just above 5200, which tends to give me about 82 knots and 800 - 1000 FPM (solo).

John,

If you set the blade pitch to get the 5200+ rpm at 75 knots (Vy), on take-off, you will easily hit 5800 rpm at WOT in level flight. The recommendation is not practical. A setting that gives you 5050-5100 rpm seems more practical.
 
Prop Setting

I agree ... prop may be overpitched..based on this and other comments. I will increace the pitch in 1/10-degree increments and see what happens. Will post results when something is worthwhile.
 
Dynamic Balance

I mentioned on here before what a believer I was in the Dynamic Balance System that Walt performed on my RV12. So after the SB...my hub had to be replaced with a new, old revised hub....things didn't seem quite the same. Sure enough, took it back to see Walt today and it was off almost as much as it was originally. Apparently just shaving those two hub sides was enough to throw it off. We had to start over...and now all is wonderful again.
 
I mentioned on here before what a believer I was in the Dynamic Balance System that Walt performed on my RV12. So after the SB...my hub had to be replaced with a new, old revised hub....things didn't seem quite the same. Sure enough, took it back to see Walt today and it was off almost as much as it was originally. Apparently just shaving those two hub sides was enough to throw it off. We had to start over...and now all is wonderful again.

Peter,

I found it quite amazing how sensitive the balance is to very slight changes in weight. A few grams one place or another can make a BIG difference. Sure is nice enjoying that famous Rotax smoothness!:D

John
 
I mentioned on here before what a believer I was in the Dynamic Balance System that Walt performed on my RV12. So after the SB...my hub had to be replaced with a new, old revised hub....things didn't seem quite the same. Sure enough, took it back to see Walt today and it was off almost as much as it was originally. Apparently just shaving those two hub sides was enough to throw it off. We had to start over...and now all is wonderful again.

I first checked Pete's RV12 with the weights installed from the previous balance and found it over the limit at approx 0.260 IPS. We removed the previous weights and started over, results below. Went from 0.460 to 0.039 IPS (the red circle in the polar plot represents the upper limit of 0.2 IPS).

Pete%252520Anderson%252520RV12%252520%2525232.png
 
John

amazing how sensitive the balance is to very slight changes in weight

Yeah John, you're so right. I think Walt has about 40 different thickness' of washers that he can use!

Pete
 
Took the 12 up for another test flight this morning. I made no changes since last flight a week ago except to top off the tank with 11 gal of fresh fuel. The temp was 32C. The density alt was 2600'. Winds 5kts from 030 on runway 10. Static run up was 4950, but held that only for a few sec. and fell to 4920 where it held steady. WOT on t.o. and rpm at 5050 at angle producing 70 kts By the time I was at 400' alt the rpms had dropped to 4900. I lowered the nose to get rpms to 5000. Climbed to 2200 msl and leveled off for about 15 sec which produced only a continued 5000. I turned onto left crosswind since I decided to stay in pattern given what was happening. I pulled throttle to 4500 then went to wot and max rpm in level flight was 5300. I again pulled throttle back to 4900, got a burble which dropped rpm to 4700. I went back to 5000 with more throttle and then adjusted speed dropping to 3750 rpm which I maintained until turning final, and then adjusted to 2200 rpm for landing. No further events. I again checked my prop blades with my Warp Protractor (I know, I know, and I am building a Tony T. style digital setup).The blades were w/i .3 degrees. I am thinking now that the prop hub, adjusting, blade match, etc. hasn't anything to do with what's going on. Clearly it must be a fuel or ignition issue. I pulled the top cowl and inspected everything and found nothing obvious. No time to pull bottom today and check plugs, but will do tomorrow. Ok, please tell me what all y'all think is going on possibly. Thanks.
Dick Seiders
 
Hi Dick,

Joe may be right but my bet would be spark plugs, we had a similar problem and went through the fuel side with no findings called Lockwood's and they said to change the plugs so we did and the problem was solved.

You should be able to find the plugs at any good auto parts but watch that they do not try to sell you the wrong plug, it will have the correct code on it, which is DCPR8E but will have a different number, the correct number is 4339, these plugs come with a screw off cap, which we need for the plug on caps to fit and the wrong spark plug has a solid cap.

Correct spark plug:

Manufacture: NGK 4339 DCPR8E

Good luck,

Best regards,
Vern
 
Dick,

Lots of good advice above. If I was a betting man with OAT of 90F I would bet on vapor bubbles in the fuel. Are you using MOGAS or AVGAS? Others have reported vapor problems with MOGAS.

John
 
I'm a little confused here with the spark plug theory. If one plug goes off line on the Rotax, the RPM drops 200? I could see that maybe if one ignition module went out. Rotax tells me there is absolutely no intermittant failure mode on the modules. They work or they don't.

The 200 RPM figure caught my attention because that was the drop I experienced several times at WOT or near-WOT on a hot engine on a hot day.

Dick, please look at your data download and see if the RPM drop was accompanied by fuel pressure drop and fuel flow increase. That will put you on the trail of either vapor formation or a malfunctioning fuel pump.

Jim
RV-12 #264
New fuel pump due in tomorrow
 
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Quien Sabe

It was the last one on the shelf at Lockwood, LEAF was all out. Hope it isn't your old one, refurbished in a new box! Can't get a debut date for the new ones...
 
Will it make a difference! A New Pump that is!

Not to worry LEAF sent mine to Kodiac, they wanted to see why it failed. But I have a feeling that it will end up in the file bin with the announcement of the new pump. You have confirmed what I had heard that the new pumps will not be in stock for a few months. Colin took off to Montana today.
 
Vern, I really don't understand how plugs with only 67 hrs on them can be causing the problem, but I appreciate the success you had, and so today I installed new plugs. Will test fly Friday.

John, I use only premium 91-93 octane mogas. One thing I did note today with cowl off. My fuel delivery line to the fuel pressure sensor lays against the cylinder cooling water hose, and the water hose also is against the sensor as well. Wondering if the heat is sufficient to vaporize the fuel in the line? I am planning to move the sensor to provide a little space, but it is in the location called for in the plans. Comment?

Jim, I will check out the Dynon data download as soon as I figure out how to do it. My 12 does have the fuel pump that supposed to be ok

Other changes planned followed by a test flight between each change.
1. reconnect trigger coil leads to main ignition module to cut out the soft start module
2. pull carb bowls to check for trash in fuel
3. Re-pitch the prop a bit flatter.

Will provide test results.
Thanks to all responders.
Dick Seiders
 
Dick, Coupla things... The fuel pump Jetguy, myself and others have an issue with is *not* the old one with the SB. It is with a large number of the current fuel pumps which have had to be replaced. This is why they are going to the new pump which will hopefully show its face this summer. I'm not suggesting the pump is your problem, it's just that a lot of old time Rotax guys reference the older 912 pump with the SB as the "bad one."

The data download process is intimidating at first for many of us north of 60. I followed the directions on the Dynon Data Download thread and it worked out OK on my second-hand laptop. I thought the idea of second-by-second info on every instrument on the panel was overkill but I am now a believer. It is invaluable in trouble-shooting problems like partial power loss.

Jim
RV12 #264
 
Installed new plugs the other day. Promised myself I would test fly with each variable change, but could not go with flying with only 4900 rpm climb rate again. So today I repitched the prop back 1.2 degrees. This change gave me a WOT static of 5150 rpm. Ignition run ups were not remarkable so took off starting out at 5150 and progressing to 5300. Respectable rate of climb in hot weather and 2800 density altitude. On leveling off rpms quickly moved to 5600 and I throttled back to 5300 at about 109 kts. Air was very turbulent so difficult to smooth out the flight, and avoid the rpm changes due to pitch changes. Key results were no burbles even with a number of increases and decreases on throttle. Conclusion: will fly for a while at this pitch setting. The pitch changes which began this series of weird engine noises seems to be (for now) the culprit. I will also re-sync my carbs as I know that might help further. I don't plan to chase possible ignition issues at this point, but may feel differently after further test flying. Will fly more tomorrow to test this setup further.
Dick Seiders
 
What tool are you using?

Dick I have to ask, are you using a digital level to set you prop? Or still using your bubble prop level?
 
John, I confess I am still using the Warp prop bubble. I have not yet fabbed the Tony T. digital brkt, but I do have the same digital level and will get to it as soon as I have a minute. I'm retired so am busier than I was when I worked 60 hrs a week to earn a living.
I did fly the 12 again this am and went up top of the scattered cover to 4500 (6600 density) and the engine ran perfectly. Take off again started at 5150 and progressed to 5300. At level off went right up to 5700 and I throttled back to 5500. In level flight in smooth air that produced a steady 115 knots. The only thing I noticed was a shift in tone (very lite, but audible) when I throttled back from 5500 to 4200 to descend to pattern alt. Perhaps the prop was pushing the engine at that point? What do you think? I'm feeling pretty good about the engine, but will use a manometer on the carbs to check balance next week, and I will fab the digital blade system.
Dick Seiders
 
Building the John Bender fixture for use with a digital level will take an afternoon. The bubble level is useless!

I was 1 degree off with the bubble.
 
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Where do ya get it?

Several times in the last 6 months I have spent a few hours on the net to nail down where to get a digital level that will read 0.1 degrees in the full range. most are angle finders with an arm attached, or only read to 0.1 at 0 or 90. I even learned how to disable the locality function on the browser, but that did not bring in many more US suppliers. Very frustrating.

I would really like to get the name or website of a supplier with the right level. Foreign made is OK. I would greatly appreciate any advice
Rod
 
Digital level

Rod,
Sent you a PM

Several times in the last 6 months I have spent a few hours on the net to nail down where to get a digital level that will read 0.1 degrees in the full range. most are angle finders with an arm attached, or only read to 0.1 at 0 or 90. I even learned how to disable the locality function on the browser, but that did not bring in many more US suppliers. Very frustrating.

I would really like to get the name or website of a supplier with the right level. Foreign made is OK. I would greatly appreciate any advice
Rod
 
I don't think it matters what you buy. They all have a tolerance of +/- .2 degrees. This tolerance means you can be off +.2 on 1 blade and -.2 on the other for a diff. of .4 degrees in worst case. Unlikely that would happen tho so I am going with it. I'll be anxious to see the test diff. between the digital and my Warp prop bubble. I suspect it will be little, but I'm willing to learn.
Dick Seiders
 
An inexpensive level...

Here is a link to the level I use. http://www.amazon.com/iGaging-Digital-Magnetic-Laser-Level/dp/B002TDE9D0/ref=sr_1_1?ie=UTF8&qid=1308537067&sr=8-1
Doesn't cost much, has a laser beam feature, and a tripod screw attachment so you can firmly attach it to your fixture. It only costs about $34 from the online supplier.
There are a jillion ways to make a fixture so you can check your prop angles. I made a simple one like this:
910442110_Yp9n6-M.jpg

Attached it to the level with a 1/4X20 screw, put it against the back of the prop and line it up on a paint stripe using the sighting notch.
932235457_yDgay-M.jpg

The fixture touches the prop at 3 places for consistent placement. Read the angle, takes a couple seconds.
There have been better, more elaborate digital level fixtures posted on the forum and easy to find with a search.

Tony
 
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