yep 78x38 is a great prop. I had c85 pistons and Vetterman exhaust on my plane. 38 pitch might be a bit course without those 2 things. The experimental thing certainly is fun!!
Climb prop C-90
- Thread starter RaisedByWolves
- Start date
cubdriver2
FRIEND
upstate NY
ReliableFlyer on here has a Catto 7834 on his C90 cub, maybe he will comment on how its working. I loved the Catto while I was using it on my 0200 cub. Even though static was only 2350 it still pulled great. You can feel the weight difference as soon as your airborne.
Glenn
Glenn
Ken Kennedy
FOUNDER
Lubbock , Tx
I heard of a guy that put a 80-30 Catto on his C85 stroker and apparently it is a hell of a performer. I heard to turns about 2350 static, and about 2600 in a 45 mph climb. Guy said it was a night and day difference between the 76AK-2-42 that it replaced; over 100 lbs harder pull on the same day which was supposedly around 5K density altitude.
Dan Gervae
FRIEND
Upper Peninsula of Michigan
Catto recommended the 76-36 for my stock O200A on my PA11EX I hope it is the ticket....I ordered one. If I can't get the static I want maybe I'll go with Lycon high compression Pistons.....was hoping to keep it stock for now. I've got lots of building to do yet but I pick up the big items as I can afford them��
mvivion
SPONSOR
Bozeman,MT
This thread has gone for 34 posts, with some incriminating evidence posted by those who are operating certificated airplanes--maybe.
Here is what the 7EC type certificate says about propellers and propeller RPM:
Engine Limits For all operations, 2475 r.p.m. (90 hp.)
Airspeed Limits Level flight or climb 100 m.p.h. ( 87 knots) True Ind. Glide or dive 135 m.p.h. (117 knots) True Ind.
Propeller Limits Static rpm at maximum permissible throttle setting: (For fixed pitch Not over 2350, not under 2125. No additional tolerance permitted. wood propeller)
Diameter: not over 72 in., not under 70 in.
So, if your current propeller pulls between 2125 and 2350 STATIC (as in full throttle, on the ground, NOT moving) then it is within legal limits. Repitch it to get better climb or cruise, and if it then runs static outside those limits, it is not legal.
And, for those folks advertising on the world wide web that their C-90s on certified aircraft are running 2600 rpm.....note that the Continental TCDS (and the above 7EC TCDS) says Maximum rpm for the Continental C-90 is 2475 RPM for ALL operations.
If you're experimental, obviously, you can do whatever you want with your engine.
But, for the OP, these are the limits for your engine. 2200 to 2300 for takeoff is probably pretty close to that static limits noted above.
Also, a review of the TC for your airplane will also tell you what propellers are approved for the plane. The TC is the first place you should go for basic information like this....THEN troll the internet.
MTV
Engine Limits
Here is what the 7EC type certificate says about propellers and propeller RPM:
Engine Limits For all operations, 2475 r.p.m. (90 hp.)
Airspeed Limits Level flight or climb 100 m.p.h. ( 87 knots) True Ind. Glide or dive 135 m.p.h. (117 knots) True Ind.
Propeller Limits Static rpm at maximum permissible throttle setting: (For fixed pitch Not over 2350, not under 2125. No additional tolerance permitted. wood propeller)
Diameter: not over 72 in., not under 70 in.
So, if your current propeller pulls between 2125 and 2350 STATIC (as in full throttle, on the ground, NOT moving) then it is within legal limits. Repitch it to get better climb or cruise, and if it then runs static outside those limits, it is not legal.
And, for those folks advertising on the world wide web that their C-90s on certified aircraft are running 2600 rpm.....note that the Continental TCDS (and the above 7EC TCDS) says Maximum rpm for the Continental C-90 is 2475 RPM for ALL operations.
If you're experimental, obviously, you can do whatever you want with your engine.
But, for the OP, these are the limits for your engine. 2200 to 2300 for takeoff is probably pretty close to that static limits noted above.
Also, a review of the TC for your airplane will also tell you what propellers are approved for the plane. The TC is the first place you should go for basic information like this....THEN troll the internet.
MTV
Engine Limits
C-FIJK
Registered User
Lewisporte N.L.
cubdriver2
FRIEND
upstate NY
Do what cub crafters does, placard by throttle " limit take off power to 2350 RPM "
Glenn
cubdriver2
FRIEND
upstate NY
I had that prop on my 0200A and would go to a 7634 if you want to stay stock. YMMV
Glenn
mvivion
SPONSOR
Bozeman,MT
Different ball game entirely. First, not a "certificates" airplane...LSA. Second, the engines in those airplane's are rated by the engine manufacturer for 2700 continuous rpm. The limitation there has to do with meeting LSA standards.
In this case, the Continental C 90 is very specifically limited by the manufacturer. You don't get to meet the static rpm limit via a placard, as far as I know.
Violate these limits at your own peril. Advertise same in a public forum, however, is rather ignorant.
FWIW.
MTV
JimParker256
Registered User
Farmersville, TX
I agree. Telling the world you're breaking the regs is only slightly less questionable than the folks who post videos of their flights that clearly show they are violating cloud clearance or other FAA rules, while advertising their names and N-numbers and even showing the pilot's face... Talk about making the FAA regulator's life easy! As a buddy of mine says "Everyone steps on their d*** once in a while. The trick is not to be wearing golf cleats when you do!"
Dan Gervae
FRIEND
Upper Peninsula of Michigan
As I mentioned...this one is for my experimental so I went with Catto....this quote is from Nicole Catto...
"our 78x34/35 is a pretty extreme power prop. It's slow. Some people really like this one,it gets off the ground fast, also a great prop for floats. the most common prop on this application (O200A) is our 76x36/37. The 36 over speeds a little bit at wide open throttle, so it's very responsive off the ground. The 37" pitch doesn't have a longer takeoff roll but will probably hit around 2750 rpm at WOT straight and level." I went with the 76x36.
"our 78x34/35 is a pretty extreme power prop. It's slow. Some people really like this one,it gets off the ground fast, also a great prop for floats. the most common prop on this application (O200A) is our 76x36/37. The 36 over speeds a little bit at wide open throttle, so it's very responsive off the ground. The 37" pitch doesn't have a longer takeoff roll but will probably hit around 2750 rpm at WOT straight and level." I went with the 76x36.
If I am reading this wrong I apologize,but the type certificate i have says 2625 for max T/O.
View attachment Scan0005.pdf
mvivion
SPONSOR
Bozeman,MT
The type certificate for the AIRPLANE takes precedence in this case. The OP described the 7AC Champ as the subject. There are lots of cases where the airframe manufacturer placed more strict limits on an engine than did the engine manufacturer. Also note that the same maximum rpm limits (2475) are specified for the C-90 installed in the Piper J-3 and PA 11.
I presume that this is because the airframe is limited to 90 hp. and the higher rpm produces higher horsepower. Nevertheless, the airframe limits are specific to the airplane, and specify the propeller limits as well.
Granted, five horsepower may seem like nothing, but the airplane is not legal if it's propeller doesn't turn in the prescribed range at static full throttle.
MTV
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mvivion
SPONSOR
Bozeman,MT
Not at all, thanks for posting ALL the data. If nothing else, that's useful to EX folks.
MTV
L18C-95
FRIEND
Oxford UK
The L18C has a higher limit for five minutes with red line at 2475 and top of green at 2350. Static on my 76 is 2300, but off the tach. I need to throttle back as soon as I start to level in the cruise. Top of green is 95mph indicated, which is reasonably correct. I cruise at 2300 RPM with 90 mph indicated.
"The 37" pitch doesn't have a longer takeoff roll but will probably hit around 2750 rpm at WOT straight and level"
With an O-200 at WOT in level flight, I like to be capable of hitting 3000 rpm. I keep it from doing so by means of instrument panel placard and retarding the throttle (standard procedure for a certified plane).
With an O-200 at WOT in level flight, I like to be capable of hitting 3000 rpm. I keep it from doing so by means of instrument panel placard and retarding the throttle (standard procedure for a certified plane).
Dan Gervae
FRIEND
Upper Peninsula of Michigan
I received and email from Catto yesterday...my prop is done. As I said, I went with the 76-36 on their recommendation, I was really torn between this and the 34 pitch, but I opted on the conservative. I look forward to finishing my project and finding out for myself how my setup matches up. I believe this is the right choice for my mission, but The proof can only come from the flying8) since the original thread was meant for a C90 and we veered off to O200, I wonder if the same prop would be the ticket on a 90. I have a C90-12F in my Tcraft on floats, but that's a certified setup, so a trial run of the new Catto would be "Illegal" on that platform, I'm sure I have enough willpower to prevent that from happening....I have a Sen 76AK-2-40 on that ship and its a winner. Still,, a comparison would be "nice".
skywagon8a
MEMBER
SE Mass MA6
It certainly would do no harm to test it on the Tcraft with some high speed taxing and other water maneuvers without the "intent" of flying.
Dan Gervae
FRIEND
Upper Peninsula of Michigan
Lol, I'm sure a lot of our membership would like to see results of some such testing. Sometimes during such a test one would encounter a gust of wind that would render him airborne and then the prudent thing (safe thing) would be to do a go around.
RaisedByWolves
FRIEND
Tx
I'm interested in what you think of the new prop.
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aktango58
FRIEND
18AA
No one around here is that careless to allow such a thing to happen; nor would anyone here ever consider anything that might be outside the FAA rules of operation
EVER!;-)
Dan Gervae
FRIEND
Upper Peninsula of Michigan
Good to know we are in the same camp
BC12D-4-85
SPONSOR
Fairbanks, AK.
As a suggestion re the Sen vs Catto...at least do a static pull with both on the same platform. Find a farm or veterinary scale used to weigh big stuff and give it a tug.
I have the same Sen prop on my Taylorcraft and it does what I want. I contacted Catto and was told the same (76-36) but haven't followed through with the order as I didn't want to end up with an expensive oar or wall decoration.
Have some fun and let us know someday...
GAP
I have the same Sen prop on my Taylorcraft and it does what I want. I contacted Catto and was told the same (76-36) but haven't followed through with the order as I didn't want to end up with an expensive oar or wall decoration.
Have some fun and let us know someday...
GAP
skywagon8a
MEMBER
SE Mass MA6
By the way, the Tcraft is a part 4 airplane. Part 4 states that you can use an unapproved wood prop. So, even though the TC specifies an approved wood prop, part 4 says it does not have to be. Hint Hint.
BC12D-4-85
SPONSOR
Fairbanks, AK.
Interesting and thank you for the obs. This is over my job class but I have seen CAR 4 5/1938, Par. 04-61 discussed versus TCDS A-696 Item 1. I suspect those involved weren't as familiar as you with the implications. I know I wasn't as a reader. But that is an excellent point...the question is which Reg pertains? Maybe that has already been answered and any further enlightenment would be appreciated.
As far as PK vs EDO, my intent isn't to imply the PK's aren't without merit in conditions like in the rough marine environment, but...in June 1980 I had the opportunity to fly two similarly equipped C-185's on the job for test purposes. Typical hot and calm Fairbanks day in the low '80's. Both planes were IO-520's with long two blade props that turned tach redline and had similar WFO T/O manifold pressures (logged the info). All-up weight was similar ~60 gallons and one soul. The one with PK 3500's (new in 1979 and latest model as of that date) I'd flown more the previous season than the newer one to me on EDO 3430's. No comparison at partial throttle/high D/A takeoff...the EDO's performed better under those conditions for T/O, and displayed a lesser tendency to pitch nose down on landing on glassy water. The PK's would go about 55 mph max indicated on the water (partial throttle with no flaps); the EDO's accelerated beyond that indicated airspeed if kept on the water. No GPS in those days so the speed may be relative. All history now of course.
GAP
As far as PK vs EDO, my intent isn't to imply the PK's aren't without merit in conditions like in the rough marine environment, but...in June 1980 I had the opportunity to fly two similarly equipped C-185's on the job for test purposes. Typical hot and calm Fairbanks day in the low '80's. Both planes were IO-520's with long two blade props that turned tach redline and had similar WFO T/O manifold pressures (logged the info). All-up weight was similar ~60 gallons and one soul. The one with PK 3500's (new in 1979 and latest model as of that date) I'd flown more the previous season than the newer one to me on EDO 3430's. No comparison at partial throttle/high D/A takeoff...the EDO's performed better under those conditions for T/O, and displayed a lesser tendency to pitch nose down on landing on glassy water. The PK's would go about 55 mph max indicated on the water (partial throttle with no flaps); the EDO's accelerated beyond that indicated airspeed if kept on the water. No GPS in those days so the speed may be relative. All history now of course.
GAP
RaisedByWolves
FRIEND
Tx
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