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O-320 FP climb numbers.

GEM930

GEM930

Well Known Member
Friend
I guess my last post (Climb RPM lower than Static) was just too overwhelming.

Sorry, just very frustrated!!!!


Let me try a different approach.... how bad are these (very honest and accurate) numbers?


104 kts/120mph 850 fmp 77f/25c 1580 LBS

126 kts/145mph 625 fpm 91f/33c 1580 LBS

96 kts / 110mph 825 fpm 93f/34c 1515 LBS
 
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Some numbers for you

Your airport is at 240' so I used 500' and your reported OAT's. I used CAFE data on the 6A to compute this with the spreadsheet you can find in the links below

120 CAS mph requires 45.45 THP at 500' and 77 degF
145 CAS mph requires 64.96 THP at 500' and 91 degF
110 CAS mph requires 41.12 THP at 500' and 93 degF

Let's assume your "320" is in good shape. With a FP prop you should be able to get 80% on takeoff even on a warm day. but let's use only 75%. Let's further assume you have a 75% propulsive efficiency under these conditions. So your BHP is 160 and your available THP should be 160 x .75 x .75 = 90 THP.

That means that you have 90 minus one of the above available for climb. Let's use 110 mph so you have 48.88 THP available for climb. I'll use 1600 pounds as worst case. You have the power to lift 1600 pounds at a rate of more than 1,000 feet per minute. Therefore 825 is likely not as good as it should be.

You can use the spreadsheet, too. PM or email me if you want assistance doing this. Since you have a 6A, you have very good drag data (from CAFE) and can just go forward with your own performance data.
 
I have an RV 9 and an o-320 with Catto 2 blade. My prop would be considered a "climb prop".

Looking at your numbers, definitely there is a problem.

While at 126 kIAS 625 seems plausible, 96 KIAS should give you around 1100 or so. At solo weight of around1475 or so, I can climb around 1700 FPM at 75 KIAS. RPM is about 2450. I don't have exact numbers but the next time I fly (Thursday) I will take some pictures and post here or on my blog.
 
GEM930 said:
I guess my last post (Climb RPM lower than Static) was just too overwhelming.

Sorry, just very frustrated!!!!


Let me try a different approach.... how bad are these (very honest and accurate) numbers?


104 kts/120mph 850 fmp 77f/25c 1580 LBS

126 kts/145mph 625 fpm 91f/33c 1580 LBS

96 kts / 110mph 825 fpm 93f/34c 1515 LBS
Click to expand...

We really need to know what rpm you were seeing at these speeds. Also, the pitch and manufacturer of your prop.
 
Sam Buchanan said:
We really need to know what rpm you were seeing at these speeds. Also, the pitch and manufacturer of your prop.
Click to expand...

I am thinking the same thing. I get the best climb performance with a FP prop by letting speed increase until the prop is turning about 2400 and then maintain that rpm by adjusting pitch. Air speed will decrease with altitude.

I have made it to 10,000 from brake release at 640' MSL in just over 8 minutes, but that is with an 0360.
 
I will look at my black box data to get the exact #s but I believe my rpm at 625 fpm is around 2250. As I stated in the other post my static rpm is 2350. I don't think I could even get the climb rpm to 2400... If I could I would be mowing my neighbors lawns! My prop is a sensenich 2 blade pitched at 79. At altitude, once I level out I can bounce off the 2600 rpm limit at around 190 mph, but the climb is horrible. I outlined way too many details in another post titled "climb rpm lower than static", but got no replys.... Figured I put too much info in and put everyone asleep before they finished reading it.
 
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me too

I?m also interested to see what others think here.

I have the same setup. RV-6a with an O-320 150HP, a Sensenich 2 blade pitched at 79. All fairings installed.

I haven?t really been keeping a super close eye on the climb rate but your numbers are about what I am getting.

With fuel and 2-people I hit 1567lbs. I climb at about 800-900fpm with about 22map, 2250rpm. But this is in the 100-deg Houston heat. Mostly I watch the CHT?s cause #3 likes to run hot on the climbs.

Although I haven?t tried, I don?t think I could turn 2400 rpm on the ground or in a climb. At about 4-5 thousand feet, WOT, I can exceed the 2600 rpm prop limit.

I?ll go out in a few days, take some numbers down and report more accurate numbers.
 
Mike D said:
I?m also interested to see what others think here.

I have the same setup. RV-6a with an O-320 150HP, a Sensenich 2 blade pitched at 79. All fairings installed.

I haven?t really been keeping a super close eye on the climb rate but your numbers are about what I am getting.

With fuel and 2-people I hit 1567lbs. I climb at about 800-900fpm with about 22map, 2250rpm. But this is in the 100-deg Houston heat. Mostly I watch the CHT?s cause #3 likes to run hot on the climbs.

Although I haven?t tried, I don?t think I could turn 2400 rpm on the ground or in a climb. At about 4-5 thousand feet, WOT, I can exceed the 2600 rpm prop limit.

I?ll go out in a few days, take some numbers down and report more accurate numbers.
Click to expand...

At low altitude and full power, you should see 28+ inches of MP. Any thoughts on why you're only getting 22"?
 
Hi Gregg,

You have a problem, regardless what your climb rate is I have never flown a fixed pitch plane of any kind where the rpm did not increase with speed, this means your static rpm of 2350 should be the lowest you will ever see. Your climb rate also looks very poor witch just backs up the fact that you have a problem.

Your engine might be just fine, I remember you saying in your other post that you have some non standard equipment involved for your engine operation. What is your setup exactly?
 
I would never trust any ROC numbers you get from air data; timed or GPS will give dependable true results.
 
David-aviator said:
I am thinking the same thing. I get the best climb performance with a FP prop by letting speed increase until the prop is turning about 2400 and then maintain that rpm by adjusting pitch. Air speed will decrease with altitude.
Click to expand...

I do same thing. Pitch for 2500 or 2600. Two up with gas, RV-4 O-320 FP I get 1200 fpm initially at 160mph, then tapers but holds about 750fpm at 140-150 mph indicated climbing. (500 ft msl, hot summer heat)

D
 
elippse said:
I would never trust any ROC numbers you get from air data; timed or GPS will give dependable true results.
Click to expand...

Roc was derived from timed climb. My vsi is generally all over the place I do not trust it as well.
 
Russ McCutcheon said:
Hi Gregg,

You have a problem, regardless what your climb rate is I have never flown a fixed pitch plane of any kind where the rpm did not increase with speed, this means your static rpm of 2350 should be the lowest you will ever see. Your climb rate also looks very poor witch just backs up the fact that you have a problem.

Your engine might be just fine, I remember you saying in your other post that you have some non standard equipment involved for your engine operation. What is your setup exactly?
Click to expand...

I'm afraid to put too much info in this post as I don't want to make it so long no one will read it (like the last one I wrote).
Rv- 6a o320 h2ad, old style pants.
Sensenich 2 blade metal 79 pitch, electronic fuel injection / ignition. Initially I suspected the timing was the problem and found it was retarded, but still have poor climb performance. I do not think its fuel as I can adjust the mixture from a rough rich condition to a rough lean condition with no improvement in climb or increase in rpm. Timing in set at 25 during high manifold pressures (like climb) and allowed to advance during lighter loads. I check the timing by setting the crank at 25 using the mark on the flywheel and the mark on the starter. I then made a mark on the back of the spinner plate that lines up with a mark I put down the center of the plenum. I checked the timing at high loads with a timing light and it indicated 25 degrees. At lower rpm the timing would advance I think up to 15 degrees, but I'm not to sure as I was only interested in high loads. How does that method sound??? Also, same prop as before efi / ei was installed. Top end is noticeably faster ... Maybe 10 mph.... Climb much worse. Engine runs as smooth as it ever did. Climb egts on # 4 are 1450, other three are around 200 degrees cooler.
 
GEM930 said:
104 kts/120mph 850 fmp 77f/25c 1580 LBS

126 kts/145mph 625 fpm 91f/33c 1580 LBS

96 kts / 110mph 825 fpm 93f/34c 1515 LBS
Click to expand...

I think you do have a problem, but it is difficult to figure out where - BTW I'm guessing you have a Sensenich metal prop? The rpm limit is 2600rpm. If you're getting 2350 rpm static that is way high - I get 2250 with a 160 & 80" pitch prop on a 6A. This set up gives me around 1100 fpm at close to your 1st condition. To get 2350 rpm static I'm guessing you must have around a 76" prop. Your climb rate should be startling! At 3000' you should be able to hit the 2600rpm redline with ease. I can't understand why the rpm would cut back in the climb - is the mainfold pressure sensor measuring the correct pressure? Is is somehow hooked into the airplane static system?

I guess that you have checked over all of your instruments (tacho, ASI, Alt, etc) to ensure your data is accurate? Have you checked your IAS against GPS ground speed?

Pete
 
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"""same prop as before efi / ei was installed. Top end is noticeably faster ... Maybe 10 mph.... Climb much worse. Engine runs as smooth as it ever did. Climb egts on # 4 are 1450, other three are around 200 degrees cooler"""

You answered your own question, there is no such thing as a coincidence, you made a major change and got a change in performance, the problem lies with some part of the changes you made. We can speculate all day and never help you, you need some real hands on help from someone who is getting good results with the setup you have, if you’re the first then you could be on your own. I bet if you put everything back the way it was it will operate normally.
 
Question, was # 4 always 200F hotter then the rest before you changed to EFI and EI? If you think that reading is accurate (probes all in the same place etc.) then this one might be your problem, 1200 ish more or less is what I would expect to see at full power, mine do have a spread between them but not 200 degrees. Have you swapped the injectors around? Can you balance the system (make just that cylinder richer)? EI has been in wide spread use for a wile now, I bet your problem lies some place with the EFI system. I would also suspect that this EFI system has changed the intake, like maybe the filter box and the carb for some sort of throttle servo, these changes could physically affect the air flow. One example is to try running vans filter box without the filter, it won?t run right.
 
penguin said:
I think you do have a problem, but it is difficult to figure out where - BTW I'm guessing you have a Sensenich metal prop? The rpm limit is 2600rpm. If you're getting 2350 rpm static that is way high - I get 2250 with a 160 & 80" pitch prop on a 6A. This set up gives me around 1100 fpm at close to your 1st condition. To get 2350 rpm static I'm guessing you must have around a 76" prop. Your climb rate should be startling! At 3000' you should be able to hit the 2600rpm redline with ease. I can't understand why the rpm would cut back in the climb - is the mainfold pressure sensor measuring the correct pressure? Is is somehow hooked into the airplane static system?

I guess that you have checked over all of your instruments (tacho, ASI, Alt, etc) to ensure your data is accurate? Have you checked your IAS against GPS ground speed?

Pete
Click to expand...

oops... 2600 rpm typing on my iphone! I fixed it in the post.

My prop is an Sensenich two blade pitch is 79.

I feel pretty confident the instruments are correct. I have checked them with the backups and with the gps. I guess the most confusing thing is my top end is better now by quit a bit. I'm sure if I changed things back it would be the same, but why has my top end improved so much? The fuel supply is routed from the pump to the #3 to the #1 to the #2 to the #4 and finally to the pressure regulator and back to the tank. I checked the injectors with a balance test and they seemed to be the same, but the test seems like it has some room for error. I suppose that perhaps the #4 could be going lean early and causing the miss and the #3 could be going rich early causing the miss on that side. That would limit my ability to adjust things, but again why the improvement on the top end? I still feel like the timing is the culprit, but have no way of testing it during climb.
 
Let's do some calcs. Using the 2.32 sq. ft. parasite drag area of a -6A for the -7A, and since induced drag area is the same as the parasite drag area at best L/D, we can solve for the best L/D airspeed. Q^2 = W^2/(S^2X2.32XpiX.81)*, with S=25,W=1515, which comes out to 24.94psf. Assuming a density altitude of 2000', Vfps=(Qx2/rhoA)^0.5**=149.2fps=101.7mph IAS. The thrust horsepower to remain in level flight is 24.94X(2X2.32)X149.2/550=31.39HP. At 2000' dalt, engine power will be 93.6%** of sea level, and if you have sea-level HP of 150, at 2300 rpm you'll have 150X.936X2300/2700=119.6 HP. Thrust HP for climb is 1515X825/(60X550)=37.88HP, therefore your total thrust HP 37.88+31.39=69.27HP which equals your available altitude horsepowerXprop efficiency. So if you're getting the full available engine power, your prop efficiency is 69.27/119.6=57.9%. If your prop is 70% efficient, your engine is 69.27/(.7X119.60=82.7% of what your altitude power should be. Try this with your own numbers.
*0.81 is the Oswald efficiency factor for the wingtips.
**rhoA= 2.37689E-3(1-2000X6.88E-6)^4.256
***(1-2000X6.88E-6)^4.756 which accounts for density and temperature effects.
 
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Oopsie

elippse said:
Let's do some calcs. Using the 2.32 sq. ft. parasite drag area of a -6A for the -7A, and since induced drag area is the same as the parasite drag area, we can solve for the best L/D airspeed. Q^2 = W^2/(S^2X2.32XpiX.81)*, with S=25,W=1515, which comes out to 24.94psf. Assuming a density altitude of 2000', Vfps=(Qx2/rhoA)^0.5**=149.2fps=101.7mph IAS. The thrust horsepower to remain in level flight is 24.94X(2X2.32)X149.2/550=31.39HP. At 2000' dalt, engine power will be 93.6%** of sea level, and if you have sea-level HP of 150, at 2300 rpm you'll have 150X.936X2300/2700=119.6 HP. Thrust HP for climb is 1515X825/(60X550)=37.88HP, therefore your total thrust HP 37.88+31.39=69.27HP which equals your available altitude horsepowerXprop efficiency. So if you're getting the full available engine power, your prop efficiency is 69.27/119.6=57.9%. If your prop is 70% efficient, your engine is 69.27/(.7X119.60=82.7% of what your altitude power should be. Try this with your own numbers.
*0.81 is the Oswald efficiency factor for the wingtips.
**rhoA= 2.37689E-3(1-2000X6.88E-6)^4.256
***(1-2000X6.88E-6)^4.756 which accounts for density and temperature effects.
Click to expand...

I can't follow all this (paragraph breaks would likely have helped) but the best L/D speed for the 6A per CAFE is 106 and on the 7A (mine) it's 110.5. No theory, just testing. In CAFE's case, with a zero thrust device. I checked their numbers against their fastest high speed at altitude and fuel consumption and I think they have it right. The IAS (CAS) for best L/D should not change with DA but the TAS would.
 
hevansrv7a said:
I can't follow all this (paragraph breaks would likely have helped) but the best L/D speed for the 6A per CAFE is 106 and on the 7A (mine) it's 110.5. No theory, just testing. In CAFE's case, with a zero thrust device. I checked their numbers against their fastest high speed at altitude and fuel consumption and I think they have it right. The IAS (CAS) for best L/D should not change with DA but the TAS would.
Click to expand...

Are those speeds knots or mph?

Thanks.
 
I used CAFE's 2.32 on the -6A for the equivalent parasite drag area; when testing a -6 I got 2.15-2.20. 'Course a -7 with greater wing area, 121 vs 110, it would be a little higher, probably more like 2.40. Using that value it comes out to 97.5 mph IAS. When you increase the parasite drag for a given weight and span, the speed for best L/D goes down, obviously, since it will intercept the induced-drag curve at a lower speed. Best L/D is not to be confused with best climb speed, especially with an FP prop, since as speed increases efficiency goes up due to higher m-dot with resulting lower power being thrown away in the delta-v, so that best climb will be at 5-10 mph higher IAS.
 
Trying to give a data point, but..

Gregg, I have no idea if this will help or just confuse everyone but, I went out for a flight today to get more accurate numbers. My intent was to give a data point and hopefully help, but now I am worried I have an issue too.:(

Set up is similar to yours except I am carbureted with slick mags.
Rv-6a, 0-320 E2A, 150HP, 1700hrs but compressions are 75 and above? Sensenich 70CM7S0-0-77, full fairings.

5min climb from 2000 and to 5500.
Pitched for 2300rpm yielded 117kts indicated
MAP = 25.3. (baro was 29.98 this day)
OAT = 98F/37C on the ground.
I was at about 1400lbs this day.

700fpm. That is a terrible climb rate for me too. I guess I will have to start looking into this. I?ll start working through the spreadsheet H.Evens has listed.

Other data for the day:
WOT runs at 5500ft yielded an average of 135kts indicated (148kts GS) @2470 RPM and 24.5MAP
WOT ground run is 2070RPM @ 28.5MAP.

So Gregg, if you figure out what the problem is, I would love to know.
 
Mike D said:
Gregg, I have no idea if this will help or just confuse everyone but, I went out for a flight today to get more accurate numbers. My intent was to give a data point and hopefully help, but now I am worried I have an issue too.:(

Set up is similar to yours except I am carbureted with slick mags.
Rv-6a, 0-320 E2A, 150HP, 1700hrs but compressions are 75 and above– Sensenich 70CM7S0-0-77, full fairings.

5min climb from 2000 and to 5500.
Pitched for 2300rpm yielded 117kts indicated
MAP = 25.3. (baro was 29.98 this day)
OAT = 98F/37C on the ground.
I was at about 1400lbs this day.

700fpm. That is a terrible climb rate for me too. I guess I will have to start looking into this. I’ll start working through the spreadsheet H.Evens has listed.

Other data for the day:
WOT runs at 5500ft yielded an average of 135kts indicated (148kts GS) @2470 RPM and 24.5MAP
WOT ground run is 2070RPM @ 28.5MAP.

So Gregg, if you figure out what the problem is, I would love to know.
Click to expand...

Too much prop.

You need to be able to hit the 2600 rpm restriction at 5500'. Even at 2600 rpm you are getting less than 75% power (<115hp) out of your engine. If your WOT run maxes out at 2470 rpm you are leaving a considerable amount of horsepower in the hangar and climb rate will suffer.
 
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elippse said:
Let's do some calcs. Using the 2.32 sq. ft. parasite drag area of a -6A for the -7A, and since induced drag area is the same as the parasite drag area at best L/D, we can solve for the best L/D airspeed. Q^2 = W^2/(S^2X2.32XpiX.81)*, with S=25,W=1515, which comes out to 24.94psf. Assuming a density altitude of 2000', Vfps=(Qx2/rhoA)^0.5**=149.2fps=101.7mph IAS. The thrust horsepower to remain in level flight is 24.94X(2X2.32)X149.2/550=31.39HP. At 2000' dalt, engine power will be 93.6%** of sea level, and if you have sea-level HP of 150, at 2300 rpm you'll have 150X.936X2300/2700=119.6 HP. Thrust HP for climb is 1515X825/(60X550)=37.88HP, therefore your total thrust HP 37.88+31.39=69.27HP which equals your available altitude horsepowerXprop efficiency. So if you're getting the full available engine power, your prop efficiency is 69.27/119.6=57.9%. If your prop is 70% efficient, your engine is 69.27/(.7X119.60=82.7% of what your altitude power should be. Try this with your own numbers.
*0.81 is the Oswald efficiency factor for the wingtips.
**rhoA= 2.37689E-3(1-2000X6.88E-6)^4.256
***(1-2000X6.88E-6)^4.756 which accounts for density and temperature effects.
Click to expand...

Huh? I feel stupid now!
 
Mike D said:
Gregg, I have no idea if this will help or just confuse everyone but, I went out for a flight today to get more accurate numbers. My intent was to give a data point and hopefully help, but now I am worried I have an issue too.:(

Set up is similar to yours except I am carbureted with slick mags.
Rv-6a, 0-320 E2A, 150HP, 1700hrs but compressions are 75 and above– Sensenich 70CM7S0-0-77, full fairings.

5min climb from 2000 and to 5500.
Pitched for 2300rpm yielded 117kts indicated
MAP = 25.3. (baro was 29.98 this day)
OAT = 98F/37C on the ground.
I was at about 1400lbs this day.

700fpm. That is a terrible climb rate for me too. I guess I will have to start looking into this. I’ll start working through the spreadsheet H.Evens has listed.

Other data for the day:
WOT runs at 5500ft yielded an average of 135kts indicated (148kts GS) @2470 RPM and 24.5MAP
WOT ground run is 2070RPM @ 28.5MAP.

So Gregg, if you figure out what the problem is, I would love to know.
Click to expand...

Maybe our O320 sixes are just slow and we have been fooling ourselves all along! :eek: Maybe I should have strapped a 360 on instead of a EFI/ EI system....Seriously, I obviously have a problem. Timing or fuel??? This would be easier to understand if the top speed had not improved so much.
 
Check your tach. I have a 160 hp 320 with sensenich prop, and I can hit 2600 rpm at any alt up to about 9000 ft.
 
If one uses CAFE one should use it for all the relevant data

elippse said:
I used CAFE's 2.32 on the -6A for the equivalent parasite drag area; when testing a -6 I got 2.15-2.20. 'Course a -7 with greater wing area, 121 vs 110, it would be a little higher, probably more like 2.40. Using that value it comes out to 97.5 mph IAS. When you increase the parasite drag for a given weight and span, the speed for best L/D goes down, obviously, since it will intercept the induced-drag curve at a lower speed. Best L/D is not to be confused with best climb speed, especially with an FP prop, since as speed increases efficiency goes up due to higher m-dot with resulting lower power being thrown away in the delta-v, so that best climb will be at 5-10 mph higher IAS.
Click to expand...

The CAFE 6A speed for best L/D as determined by a zero thrust device was 106 mph. You used a different number. If you use their flat plate number it would make sense to me to use their V L/Dmax.

I understand the difference between Best L/D and best climb. The best ROC without consideration of the engine & prop will be at the speed for minimum sink which is about 76% of best L/D. However, engine and prop force a change in that number. In my case, my best ROC is around 105-110 KNOTS because of my cruise-pitched Catto. That's as much as 35 knots faster than the theoretical best ROC speed.

Notwithstanding any theory, my 7A's best L/D speed is 96 knots=110.5 mph; a little higher than the 6A, but not using a ZT device, just a method I find to be equally useful if slightly less precise. Yes, I have longer wings but I also have longer main gear, different tail. Whatever the reason, that's what the airplane actually does.

So much for facts that are, I think, well established. Now an opinion. I think that a valid, repeatable testing model (such as mine, for example) is indispensable when discussing aircraft performance. We can guess all we like about wing area, tip efficiency, etc., but the airplane still does what it does and we need to be able to fit the data to a model that incorporates all the known data so that the outliers can be detected.
 
Gregg,
Maybe we can track down the issue systematically. We have a few variables between us. You have EI and FI, and I have mags and a carb, but we may or may not have the same issue.

Vans recommends a 70CM7S9-0 (78) for the 150HP O-320.
I have a 70CM7S0-0 (77) Difference from the recommended prop is, my prop is 1? under pitched and without the 2.25? spacer.
I would guess you have 70CM7S?-0 (79)

If Sam is right, then it maybe the prop, but you said you had better performance before with the same prop. So this is strange.

My timing is dead on and compressions look good. Fuel flow is showing around 14gph on WOT, full rich. I cruse at 135kts indicated at around 7.2gph. But I see very little performance increase with more throttle, and I am using a lot more fuel.

Maybe someone took the lead out of the fuel without us knowing. :)

Can anyone think of what we should check next? Intake, filters, valves???
I will calibrate my timing again, but not sure this will help.
 
Mike D said:
Can anyone think of what we should check next? Intake, filters, valves???
I will calibrate my timing again, but not sure this will help.
Click to expand...

Could your cam be going flat?

Do a compression test. Use a tester that screws into the spark plug hole and reads compression by cranking the motor with wide open throttle. This will tell you the intake volume of each cylinder. A flat lobe = low volume = low power.
 
Mike D said:
Gregg,
Maybe we can track down the issue systematically. We have a few variables between us. You have EI and FI, and I have mags and a carb, but we may or may not have the same issue.

Vans recommends a 70CM7S9-0 (78) for the 150HP O-320.
I have a 70CM7S0-0 (77) Difference from the recommended prop is, my prop is 1? under pitched and without the 2.25? spacer.
I would guess you have 70CM7S?-0 (79)

If Sam is right, then it maybe the prop, but you said you had better performance before with the same prop. So this is strange.

My timing is dead on and compressions look good. Fuel flow is showing around 14gph on WOT, full rich. I cruse at 135kts indicated at around 7.2gph. But I see very little performance increase with more throttle, and I am using a lot more fuel.

Maybe someone took the lead out of the fuel without us knowing. :)

Can anyone think of what we should check next? Intake, filters, valves???
I will calibrate my timing again, but not sure this will help.
Click to expand...




WOW 14 gph! The most my black box showed on the last flight was 9.5 on my WOT run at 7000' density alt. (166kts)true. During climb (lame as it is) I show a burn of 8.6.

We might be on to something.
I'm still trying to get my fuel flow calibrated... but it seems close, usually indicating within 1/2 gal at fill ups. I usually indicate having 1/2 gal more than I really have, so my burn rated are low, but it cant be that much.

My compressions at last inspection were 78s and 79s. but that was a leak down. Maybe Ill try to screw a gauge in and crank it, but wouldn't it still hit the same #s if the cam was going flat, just a little slower??? Anyway that would go against my top speed increase.

I still feel like if it was a fuel problem I should be able to manually adjust it out with the mixture. I can go rich enough to make the engine stumble on climb, but nothing really changes up to the stumble point....
I'm so lost?
 
Before we get caught up in posting very accurate speeds for best L/D, let's keep in mind that this speed increases 1% for each 2% increase in weight, and increases 1% for each 2% decrease in parasite drag area, so you really can't post an exact number unless you know these exact values. I was merely trying to give some generalized data based on calculations rather than subjective observations, since these speeds are dependent on conditions. I think this kind of information is much better to compare a person's performance against instead of a lot of claims from people with somewhat different configurations. For instance, using 25' span, EFP of 2.4 sq.ft., and weights of 1450 lb and 1650 lb, gives 95.8 mph IAS at 1450 lb and 102.2 mph IAS at 1650 lb. The curve of induced drag starts high at low speed and decreases with speed squared. The curve of parasite drag starts low at low speeds and increases with speed squared. Where the drag forces cross, that is the best L/D and the two are equal. So if you decrease parasite drag for a given induced drag curve, they will cross at a higher speed. And since induced drag increases with weight, for a given parasite drag, the induced drag curve at higher weight crosses the parasite drag curve at a higher speed.
The RV-8 I tested had 150 HP O-320 and used a Sensenich 70CM6S9-0-77 and its speed and ROC were less than inspiring, and he could turn 2600 rpm max. Jim Smith with his 3-blade Ellipse prop goes a GPS-measured 192.3 mph TAS at 2738 rpm at 6440' dalt and averages 916 fpm from 2000' to 10,000'. His static rpm is 2125.
 
0-320 vrs. 0-360

Gregg -

Don't get too remorseful about not having an 0-360. I purchased my 6A with a run-out 160 hp 0-320 and flew it for 4 years. I swapped it out for a 180 hp 0-360 and I have been flying behind it for 2 years. I have not noticed much performance difference other than the rate of climb appears to be sustained to higher altitudes. I replaced the engine (2800 hrs TTSOH) for peace of mind because I fly over the Sierra and Cascades on a regular basis. The one plus I have noticed is people seem to be willing to pay $10,000 more for a used RV with the bigger engine and it only cost about $1,000 more to purchase new. The 0-320 is back in a certified airplane and still chugging along.

I used a Sensenich prop with both engines and I have the old style (blisters) wheel pants. I did some experimenting with the pitch and went from about 2150 rpm static to 2250. I gained about 200 fpm climb and lost about 5 mph in cruise.

I will be in Oroville (OVE) tomorrow getting some work done on the plane. I am flying out of Livermore when the fog clears and should be there between 1000 - 1400 hrs. Stop by if you are in the area. I can not help you with your technical stuff, as I am a flyer not yet a builder, but I can tell you what I have experienced flying my 6A for 6 years.
 
I've actually moved to a private air park south of Sacramento. Alta Mesa Airpark in Wilton 3CN7 in Airnav, but not on the sectional yet. Not too far out of your way. Stop by if you like. 2600' paved 40' wide.

Would love to Chat!

Gregg

If your interested in stopping by give me a call 530-228-5399. I'll give you some pattern info. The AP manager is a wound a little tight here. Gotta fly a pretty conservative pattern.
 
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GEM930 said:
WOW 14 gph! The most my black box showed on the last flight was 9.5 on my WOT run at 7000' density alt. (166kts)true. During climb (lame as it is) I show a burn of 8.6.

We might be on to something.
I'm still trying to get my fuel flow calibrated... but it seems close, usually indicating within 1/2 gal at fill ups. I usually indicate having 1/2 gal more than I really have, so my burn rated are low, but it cant be that much.

My compressions at last inspection were 78s and 79s. but that was a leak down. Maybe Ill try to screw a gauge in and crank it, but wouldn't it still hit the same #s if the cam was going flat, just a little slower??? Anyway that would go against my top speed increase.

I still feel like if it was a fuel problem I should be able to manually adjust it out with the mixture. I can go rich enough to make the engine stumble on climb, but nothing really changes up to the stumble point....
I'm so lost?
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I would go back to whoever sold you the fuel injection system and have an indepth conversation about the fuel flow map. I would be interested to know what parameters the map uses to determine the fuel flow. From your FF nukmber it sounds like you are running very lean - what are your CHTs doing? You should aim to keep them below 400F - and that usually means high fuel flows in the climb - like 14gph. Perhaps you have found the problem? There just isn't enough fuel getting into the cylinders. When you go rich to make the engine stumble what is the FF? If it isn't significantly above 14gph then is it the mixture that is causing the engine to falter? Do you have direct manual control of the mixture, or is it just another input into the FADEC?

Pete
 
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It is just an input, it allows one to choose between best power or best economy, however if tuned correctly the engine should run correctly through all stages of flight without touching the controller. You would just have less power less burn or more power more burn. The unit is an Ec3 made by Tracy Crook at real world solutions. The unit uses RPM under 1200 rpm and MP above. It also uses temperature. It comes with a base map and you have to fine tune it to develop a "correction table" for your particular aircraft/installation. The fuel map seems to be the obvious culprit except for being able to enrich it enough to make the engine rough and still not get any improvement along the way. I'm going to step out my door and fly for a few minutes. I'll report back on the FF just before the rough condition.... And yes my CHTs are high.

Thanks again for all the help. You guys are great!
 
Okay,embarrassing but, I have to admit I am a newbie and have committed pilot error.

I was always taught to have full mixture in when taking off, landing or climbing at full power. Yes I am a flat lander. But where I learned to fly (SF area) 98 deg temps were not a problem. The issue of low numbers on the climb and static runs was an issue of not accounting for density altitude in combination with a low powered and forgiving engine.

At 98F the density altitude was 2500 ft. So the use of full mixture was not good for creating full power.

Today, I used the leaning function of the GRT (yep, still learning) and I did much better. 2550 RPM at 155kts indicated. I have a 2600 limit on the prop so I had the throttle pulled out a little.

Gregg I would suspect you may also have a leaning issue. (over leaned)

But I did hear, from a reliable source, that a cam gear could be off by one tooth, causing you to lose around 300RPM. He had experience with one engine that had this issue. They removed the valve cover on the #1 to test the valve timing. This is hearsay, but that is one more thing you can check.

Hope this helps.
 
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Mike D said:
Today, I used the leaning function of the GRT (yep, still learning) and I did much better. 2550 RPM at 255kts indicated. I have a 2600 limit on the prop so I had the throttle pulled out a little.
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I think I need a GRT
 
Mike Macon said:
Gregg -

I will be in Oroville (OVE) tomorrow getting some work done on the plane. I am flying out of Livermore when the fog clears and should be there between 1000 - 1400 hrs. Stop by if you are in the area. I can not help you with your technical stuff, as I am a flyer not yet a builder, but I can tell you what I have experienced flying my 6A for 6 years.
Click to expand...

You missed a good feed at the tandem-wing fly-in in Livermore. They even allowed a couple of -9s in! Those pilots were kept to the side when the composite guys wanted to yak about that krinkly aluminium. But guess who walked around with a T-shirt that on the back said: "Friends don't let friends fly in planes that corrode!"?
 
Plastic Planes

Paul -

Yes, I saw the gaggle of Velocities, etc. as I was taxiing after landing around 1800 hrs. My hangar is east of where you were and I could smell the bar-b-que. Dave Dent has helped me out on a couple of occasions with my RV. I like the airplanes but they land a little long for my taste.

Gregg -

I will have to take a rain check on visiting your field in Wilton. I would really like to check it out but Saturday had some funky winds and weather so I just did an over and back while the getting was good. I will call prior now that I have your number.
 
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David-aviator said:
.....I get the best climb performance with a FP prop by letting speed increase until the prop is turning about 2400 and then maintain that rpm by adjusting pitch......Air speed will decrease with altitude. I have made it to 10,000 from brake release at 640' MSL in just over 8 minutes, but that is with an 0360.
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Reading through this thread piqued my curosity and some of the ideas presented here, including Dave Domeier's technique for a timed climb seemed like a good thing to try. So, this morning before the clouds rolled in, I gave it a go. My 160 H.P. O-320D1A is fitted with the Sensenich fixed pitch (79) propeller. The field elevation is 529' MSL and the baro was 30.16 with an OAT of 73°. Flying solo with a full load of fuel onboard (38 gallons) I proceeded with the test. With the brakes locked, full static RPM as reported on the VM1000 engine monitor comes in at 2250-2260 RPM. A half second before applying full throttle for a straight out departure on runway 27, I activated the timer function on the transponder. By adjusting the pitch attitude at constant full throttle, I tried to maintain that 2250 RPM throughout the duration of the climb test. Enjoying an initial climb rate of approximately 1500 FPM, that dropped off considerably as I gained altitude and really dropped off after passing 6000'. In the end, I reached 8000' MSL (OAT 62°) in 7 minutes 41 seconds. The elapsed time indicates a ROC that averaged approximately 1079 FPM to 8000'. Not too shabby for an O-320 turning a little ol fixed pitch prop.

Video shot last year: http://www.youtube.com/watch?v=pV99wQqyb8g
 
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Wow... Thanks for making me feel worse! Ok now that it is obvious I have a problem I gotta figure out what it is !!!
 
Good show, Rick.

Problem with FP is getting the rated HP out of the engine on take off and climb.
Your time to climb was good considering at 2250 rpm the engine was developing about 120HP.
 
Mike Macon said:
Paul -

Yes, I saw the gaggle of Velocities, etc. as I was taxiing after landing around 1800 hrs. My hanger is east of where you were and I could smell the bar-b-que. Dave Dent has helped me out on a couple of occasions with my RV. I like the airplanes but they land a little long for my taste.

.
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You should have come by! There was plenty of chicken and dogs left!
 
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