O-320 FP climb numbers.

[GEM930]

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

[hevansrv7a]

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.

[apkp777]

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.

[N941WR]

What airplane do you have?
Are your fairings installed?
Details, we need details.

[Sam Buchanan]

Originally Posted by GEM930

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

We really need to know what rpm you were seeing at these speeds. Also, the pitch and manufacturer of your prop.

[David-aviator]

Originally Posted by Sam Buchanan

We really need to know what rpm you were seeing at these speeds. Also, the pitch and manufacturer of your prop.

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.

[GEM930]

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.

[Mike D]

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.

[Kyle Boatright]

Originally Posted by Mike D

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.

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

[Russ McCutcheon]

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?