0-290 D Prop on a CB-1

Discussion in 'Waco & Hatz' started by sarpysam, Sep 2, 2018.

Help Support Biplane Forum by donating using the link above.
  1. Sep 2, 2018 #1

    sarpysam

    sarpysam

    sarpysam

    Active Member

    Joined:
    Aug 19, 2013
    Messages:
    40
    Likes Received:
    3
    Guys: I recently completed #932 with a 135 hp 0x290. I started with a Sterba 74x50 but it wouldn’t turn up. Replaced it with a 74x48 metal and it barely made 2500 just shy of 100 mph. Ed repitched the 50 down to 47. It, too, is just short of 2500 but blows through 115 mph. We’re still shy in my way of thinking. There’s a lot of hp in that last 200 rpm and I don’t want to go 115 mph! Ed’ll repitch it again but we’re looking now at confirming the tach reading and I’ll confirm the a/s with a GPS.

    What are you guys running out there for props?

    Sarpy Sam
     
  2. Sep 2, 2018 #2

    TFF1

    TFF1

    TFF1

    Well-Known Member

    Joined:
    Apr 30, 2010
    Messages:
    3,261
    Likes Received:
    603
    Too little pitch and it will only fly at full throttle. The prop will be a big speed brake at part throttle cruise. I bet 115 is 15 faster than the O-200 ones. It's a big plane and never meant for speed. You could try borrowing a Sensenich in the 50 pitch range to check prop efficiency. Might find a McCauley to borrow too.
     
  3. Sep 2, 2018 #3

    bipe215

    bipe215

    bipe215

    Well-Known Member

    Joined:
    May 17, 2007
    Messages:
    162
    Likes Received:
    42
    Sarpy,

    What kind of cruise and climb numbers are you seeing?

    Steve
     
  4. Sep 2, 2018 #4

    sarpysam

    sarpysam

    sarpysam

    Active Member

    Joined:
    Aug 19, 2013
    Messages:
    40
    Likes Received:
    3
    I’ve got to keep the 47” prop pulled back to 2200 to keep the cruise below 100. Pretty sorry way to break in a fresh overhaul. Is anyone running a 45 or 46” pitch out there on the 135.

    Sarpy Sam
     
  5. Sep 2, 2018 #5

    Dennis Flamini

    Dennis Flamini

    Dennis Flamini

    Well-Known Member

    Joined:
    Sep 7, 2007
    Messages:
    2,216
    Likes Received:
    844
    Sensenich wood lists 74 x 47 to 74 x 54 for o-290 on various Pipers.
     
  6. Sep 2, 2018 #6

    EAABipe40FF

    EAABipe40FF

    EAABipe40FF

    Registered Users Supporting Member

    Joined:
    May 30, 2009
    Messages:
    5,081
    Likes Received:
    957
    What Sensenich metal , AM or DM?

    I'm running a 76AM6 X 48(74" long) on my 125 horse O290 G/D on the Spezio. I get 2300 static. Probably less drag, I get 105 mph at 2500, WOT is 2700 and 115 mph.

    I have a 74 X 50 Culver and the same engine will static 2100 and barely fly...I should have aborted the TO. WOT yielded only 2250 and 90 mph. Too thick.

    The above 76AM6 X 48 is exp.(too thin) I had a certified rebuilt 76AM6 X 46(also 74" long) and it gave the exact same numbers.

    I suspect an inch or two of pitch won't make a big difference in cruise speed but OTOH might make a bigger relative difference in climb?

    Jack
     
  7. Sep 2, 2018 #7

    160hatz

    160hatz

    160hatz

    Member

    Joined:
    Nov 15, 2017
    Messages:
    11
    Likes Received:
    0
    Just an FYI I don't think this will help you???

    My CB-1 0-235 1oo hp 883 LB 72x49 Mc Cauly 2300 static 2250---90mph

    Will b trying new Culver this week 74x39 ?????????
     
  8. Sep 2, 2018 #8

    Dave Baxter

    Dave Baxter

    Dave Baxter

    Well-Known Member Lifetime Supporter

    Joined:
    Nov 15, 2007
    Messages:
    1,671
    Likes Received:
    783

    Sam sometimes its not just the prop? There are some O-290 engines that will swing that prop, due that they deliver some good honest HP, and others that are wimpy, and the reasons are not always apparent! The same is true about airplanes, again for what ever reason the air on some does not want to go around over the airplane or through the engine compartment efficiently. Not saying this is the case, but could be part of the problem? Especially if other similar airplanes are able to swing that prop and engine combination to the published numbers? Dave
     
  9. Sep 3, 2018 #9

    Morphewb

    Morphewb

    Morphewb

    Well-Known Member Lifetime Supporter

    Joined:
    Jun 6, 2009
    Messages:
    1,505
    Likes Received:
    584
    Definitely get the tach checked before you do much of anything else. There were some folks who sold digital tach checkers at OSH back when anything digital was still fairly new. You initially checked the accuracy of the digital unit by reading the cycles of a fluorescent light bulb. I checked my airplane on the way home. It was showing almost 100 RPM low at full throttle. Checked five other airplanes when I got back and ALL were off. All of the airplanes had the standard AC style cable driven analog tachometers. Most errors were showing low by nearly 100 rpm at full throttle but was varied at lower RPM ranges.
     
  10. Sep 3, 2018 #10

    Larry Lyons

    Larry Lyons

    Larry Lyons

    Registered Users Lifetime Supporter

    Joined:
    Oct 1, 2012
    Messages:
    3,872
    Likes Received:
    923
    Don’t remember the prop numbers now but my 0-235 turns 2350 static, 2700 WOT, gives me an honest 105 kts.
     
  11. Oct 11, 2018 at 3:34 AM #11

    Dana

    Dana

    Dana

    Well-Known Member

    Joined:
    Oct 13, 2014
    Messages:
    501
    Likes Received:
    164
    I believe my prop to be a 74x52 (per one note in the logbook) M76AM-2 (per a note about the AD that applies to that model) but I haven't yet removed the prop to see what markings it has. With the 125HP O-290 I cruise at 70 knots (81mph) indicated at 2300 rpm, I get 2500 in a full throttle climb at 60 knots (69 mph). Max rpm in level flight is around 2600, not sure of the speed. But I don't know that the airspeed indicator or tach are accurate. With round cables instead of streamline wires my plane is draggier than most.
     
  12. Oct 12, 2018 at 3:45 PM #12

    sarpysam

    sarpysam

    sarpysam

    Active Member

    Joined:
    Aug 19, 2013
    Messages:
    40
    Likes Received:
    3
    Thanks for the input guys. Dana....what’s the empty weight on your airplane? Mine came out at 1028# which is considerably heavier than I had anticipated and may be the source of the difference in the required pitch’s.

    Sarpy Sam
     
  13. Oct 12, 2018 at 4:35 PM #13

    Dana

    Dana

    Dana

    Well-Known Member

    Joined:
    Oct 13, 2014
    Messages:
    501
    Likes Received:
    164
    975 empty, 1550 gross. Flying by myself with full fuel it's around 1250.

    If I get a chance this evening I'll try to take some measurements of the prop, I want to know for sure what it is anyway.
     

Share This Page