Mach1

My Feedback: (5)

Does anyone have the listing of what CP equals what thrust for
the RAM 750F handy?

THanks in advance

rcs1313

I looked in the 750F manual but did not see any listed. BVM listed the values for the 750 in their INLET newsletter...VOL 28 as the following:

1250 mb=17 pounds of thrust
1200 mb= 16.3 pounds of thrust
1100 mb = 15 pounds of thrust
1000 mb = 13.9 pounds of thrust
900 mb = 12 pounds of thrust

Remember also that, Ram suggested a reduction of 35 mb for every 1000 feet of density altitude .


The above values were for the 750

Woketman

My Feedback: (6)

Mach 1, are you certain that you are asking for the values for a 750F? The reason I ask is that the ECU that came with the 750F was not adjustable for max CP by the user and so they did not give you a CP vs, thrust table in the manual. If you have a 750P, the ECU was adjustable (when you get to the correct point in the set up menu, every time you hit the start button, the red one, it lowers the max CP by 100 mb) and I have the values of CP vs. thrust for that.

Mach1

My Feedback: (5)

Yep, it's an F model...I just changed the 'old' ecu for one of Andy's
that allows you to set max cp and glow values. The RAM ECU would take the engine to 1325 max. Andy lists in his manual that
his ECU was preset for max at 1314 mb, however when I was
going through the set up, max was set at 1413 mb. The next
step down is the 1314.
There is a CP/Thrust chart in the manual for the 1000.
Is it fair to assume that the 750 and the 1000 are
producing the same thrust up to the 750 max cp limit?

Woketman

My Feedback: (6)

No, I do not believe that is a good assumption. I believe that one of the ways that the 1000s & the 750Ps can make more thrust for the same physical size engine is that they use a slightly bigger compressor with a greater throughput. But you'd still think that at the same CP there would be roughly the same thrust, but I don't think it is that linear. I ran a 750F for quite a while and then I was given a 1400 ECU to bump up the thrust. I was told that if the engine ran vibration free at 1400 CP, then it was OK to run it like that, but obviously there is going to be a shorter bearing life at 1400 than at 1300. So I never ran at full CP except for vertical maneuvers, takeoff and so on. But then again, depending on the airframe/engine combo, that's usually a good idea anyway. Bottom line is that we know that, on a 750F, 1300 is about 17 pounds, so 1400 is somewhere around 18 to 18.5 pounds.

Woketman

My Feedback: (6)

P.S. Were you at Superman 2001? If you were, you may have seen my Hot Spot flying. I had a 750F running at 1400 and it had tons of thrust for that Hot Spot. I only used it vertically as I was having that aeroelastic issue with the wings where they were flexing at high speeds. So I basically just did touch & goes, slow flight and vertical climbs to be safe until I could glass the wings.

TonyF

My Feedback: (92)

You should not be running a 750F at 1400mb. That will overspeed the engine and dramatically shorten bearing life. Also, the 35mb for every 1000 feet starts at the 750F max of 1300 mb.

1300 mb on a 750F is not the same thrust as 1300mb on a 750 Plus or 1000. They are different wheels.

Mach1

My Feedback: (5)

Thanks Woketman...I got the ED ECU so I could LOWER the thrust of the 750 down a bit to around 15lbs. Thanks for the input. I thought the 1413 max cp was quite high for the F series.