Rocket performance - seems a little low

[Dklossner]

Below is the actual performance of a 1981 Mooney Rocket I am considering buying.  These numbers seem a little low and I would like other opinions.  There are 3 test, climb, max cuise and economic cruise, thanks. 

 

	Test Flight Data Sheet					Date	10/8/2010
						OAT	18	C
						Pressure	30.12
						Location	NC
TEST 1 Takeoff - Climb Performance- expectation - within 7 knts of published data
100% Power, MAP 38", 2650 RPM, 108KTAS – should be 1650 fpm
What is actual FPM?
		1500
What are engine temperatures?
	CHT1	CHT2	CHT3	CHT4	CHT5	CHT6	Oil Temp
	367	370	380	361	366	350	180
What is the oil pressure?
		65	psi
Test 2 Level Flight Cruise Performance - expectation -within 7 knts of published data
Max Power Continuous - should be 200 ktas @ 25 gph:
80% Power, MAP 34", 2400 RPM, 50 degrees rich of peak @ 5,000 ft
	What is actual KTAS - measured in 4 directions - average?
	North	East	South	West
KTAS	179	179	179	179		no-wind - calm
What are engine temperatures?
	CHT1	CHT2	CHT3	CHT4	CHT5	CHT6	Oil Temp
	373	378	378	356	378	367	176
What is the oil pressure?
		65
Test 3
Economy Cruise – should be 180 ktas @ 14 gph:
55% Power, MAP 26", 2200 RPM, 50 degrees rich of peak @ 5,000 ft
What is actual KTAS - measured in 4 directions - average?
	What is fuel flow?				14
	North	East	South	West
KTAS	155	155	155	155		no-wind - calm
What are engine temperatures?
	CHT1	CHT2	CHT3	CHT4	CHT5	CHT6	Oil Temp
	350	353	357	336	357	338	175
What is the oil pressure?
		65

[carusoam]

David,

Just for clarification....

[1] What did you use for measuring KTAS.  Can I assume GPS derived data?

[2] Why did you select 5,000 ft for your comparisons?  The rocket is a turbo monster, but monster performance probably does not become apparent until much higher in the atmoshpere.  5k is somewhat low for most mooneys I think?

[3] Where did you get the "should be" numbers?  At economy: 180kts at 14gph seems optimistic to me.

I fly an M20R and to get to 180kts, but it costs me significantly more gph to go there.  OK the M20R is slightly heavier and a little larger, but it makes me ask the question anyway.

I am looking forward to the discussion, real help will arrive soon...

Best regards,

-a-

Sorry: I don't know what happened to the margins.  When I write / edit the paragraphs they are full width......

[Dklossner]

Thanks for your reply.  Yes - all airspeeds were derived from a Garmin 430 GPS

I selected 5,000 ft, because I wanted to see how the plane performed at the lower level.  I was thinking that your could extrapolate - maybe you can’t,  I was hoping that other Rocket owners would have these performance numbers. 

“The should be numbers” come from Rocket. 

Thanks again,

 david

 

[carusoam]

 Search on this board for "rocket"

Look for RJBrown and Wojo.  Both have significant rocket experience.

[carusoam]

 Search on this board for "rocket"

Look for RJBrown and JasonWojo.  Both have significant rocket experience.  One might even have one for sale......

[RJBrown]

Rocket Engineering performance data starts at 12000' and up. Your data compares to nothing published. The advantage of a turbo is at the higher altitudes. I live in the Denver area and based my Rocket at APA. The airport elevation is 5880'. I normally flew above 12 on every flight. If altitude is not an important consideration then you will spend more for a small advantage at low levels. At 12-14 I would get 200KTS at 20 GPH. Higher would be faster on the same fuel. Eastbound I would fly at the highest altitude passengers were comfortable. Alone I would wear onboard oxygen with a backup bottle on the passenger seat and fly high. West bound I would get high enough to find cool smooth air and balance altitude against headwinds. If oxygen is not an acceptable option why buy a Rocket?

I found that the numbers on the sunvisor published by Rocket were conservatively accurate.

5000' is an inappropriate altitude to "test" a Rocket. The numbers are meaningless. If you intend to fly at lower altitudes and want increased performance the Missile conversion would be a much better choice. Missiles also carry a much smaller premium in today's market. Under 12 the Missile will cost less for the same performance.

Randy Brown

[Parker_Woodruff]

You will get higher TAS as you go higher in altitude.  this is because the Turbo allows for power settings at higher altitudes that can only be accomplished down low in a normally aspirated aircraft.

There's less air up high, that's good because it's less drag.  Since you're still making great power with the turbo, you get a higher TAS as a result.