My 601XL has a 69" 48 pitch currently, with a C-0200 rated at

125 HP.  At 2300RPM I am just at 100MPH, I want to be at 115MPH

at 2100RPM (RPM X Pitch X .000947 = MPH), This would call for a 69" 58 pitch prop.

 

What are other Flyers out there using on 125HP engines for Dia. and Pitch?

 

Also is 115MPH cruse acceptable and safe.

 

This 601xl has the wing mod.

 

PS: Getting 125HP out of a 0200!!, 10-1 comp pistons, port/polish

super balance, two E-Mags tuned Exhaust system. 

 

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Comment by Bob Pustell on June 25, 2013 at 7:27pm

Oh, forgot to address the question of safety at 115 MPH that Charles asked. My opinon (which is worth exactly what you paid for it, not much) is that cruising at or below the green arc is safe and reasonable. That would be at or below 124 MPH for our birds according to Dr. Andy Elliot's POH. In the event of really nasty turbulence (or a significant chance of encountering that level of turbulence) it would be prudent to slow to Va (maneuvering speed) in order to have an even larger safety pad, in my opinion. Va for our birds that is 103 MPH.

Cruising above the green arc is inviting trouble, in my opinion, even if you have the power to do it. You can NEVER have an absolute guarantee of totally smooth air and it is only safe to be above the green arc in totally smooth air.

My two cents.........

Comment by Bob Pustell on June 25, 2013 at 7:17pm

I agree with Louis. I have flying privileges in a 601XLB trike with a 120-ish horsepower Lycoming O-235. It cruises at 120 MPH on about 2400 RPM, 115 would be maybe 2375 I would guess. The prop is a Sensenich wood prop, I do not know the model number but will try to get it for you. As Louis says, you will need to turn more RPM than 2100 to go that speed in a 601XLB. Besides, airplane engines like to be run hard -- lugging them is not healthy in the long run. Why are you so focused on a particular RPM for a particular speed?

To answer Louis' question, this aircraft will do 140 at WOT while turning 2600 RPM. The extra cubic inches and HP from the big (for this airplane) engine make a difference. I plan to power my 601XLB taildragger with the 3000 cc version of the Corvair in order to get some of those extra ponies.

Bob

Comment by Louis W. Ott on June 25, 2013 at 1:07am

Charles,

What TAS, and RPM, do you see at WOT?

I have a 601XL B with 2700cc Corvair engine (100hp) and get 115 mph TAS at 3000 rpm with 68" Warp drive prop set to 8.7 deg pitch. Totally different prop so not a direct comparison. WOT gets about 3200 rpm and around 125 TAS.

I think you'll need to turn significantly faster than 2100 RPM to get the power needed from the engine to go 115 mph TAS.

Louie

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