A rocket guy (airline pilot also) had a prop strike at my home airport. He told me his yearly insurance bill was approx. $4,000.
Wow. Rocket men, is that true?
A rocket guy (airline pilot also) had a prop strike at my home airport. He told me his yearly insurance bill was approx. $4,000. That is alot of dead dinosaurs you can burn for fun if you had an 8.
Rockets are awesome but I can't aford the insurance.
...I don't know if I would agree that the gear feels like wet spaghetti, in fact mine feels very solid...
Thanks for all the great info.
Last question regarding the nose over. The airport I'm at has a 1 grass strip 1600' and 1 paved, 2000'. Is grass ok for the HRII and 2000' on the edge?
Thanks again.
I fly both.
Quick observations:
The Rocket Will have lower fuel flow than the -8 at the -8's cruise speed.
Interesting, I would have guessed that they'd be pretty close but I fly my 7A quite a bit with my friend who has a Rocket. He slows down so we can fly places together and always seems to use quite a bit more fuel.
I'm not doubting your statement since you fly both airplanes. Maybe it's all in the takeoff since he can pretty much go straight up.
Speed is only part of the appeal of a Rocket.
The ability to climb out of a mineshaft also comes in handy at times.
Wow. Rocket men, is that true?
We have to put up with the high smug emissions you guys are leaving on this website.
We lowly sport-wing Rocket guys can only dream to have EVO wings.
No one's mentioned stall speeds. IIRC, the HR2 adds 33% to gross weight (500 lbs), clips the wing slightly, and claims a stall speed 1 mph more than a -4...
To be clear, my comments about stall speed were about the Harmon Rocket II; I've never inspected the numbers published by F1Boss for the F1 Rocket (I did look closely at the SBS cabin mockup at OSH, but it never materialized before I pulled the trigger on the -7).
Someone mentioned acro. Again: isn't the RV4 rated at 1300 lbs gross for acro? Same spar, and almost the same wing area (meaning span) on an HR2, so is it rated for acro in remote control mode only?
Charlie
....However, pushing the -8 up to its max cruise of 175 also pushes the fuel flow up to about 11+. I can easily beat this with the Rocket, as 11 GPH buys me me 190-195KTAS.
This photo was taken over Alabama in June, so OAT is high enough to push my personal temperature limits with the cowl door shut. However, it does illustrate the effect of aero cleanup on an -8:
Mark, do you have your own spray business?
Best,
I work as a spray pilot in Brazoria County, and I have occasion to cruise the short distance there at 7500/8500. I set up 22"/2200/11GPH every time.
TAS work out to 200-204 every time. IAS...hmmm...maybe around 175?
Now, I would have guessed that same FF being the driver, the planes would be very close in TAS, especially at that altitude where the 8 wing works very well.
So, I wonder how can this be? Would the answer be as easy as a ROP OP vs an LOP OP? Some head scratchin' going on here...
This photo was taken over Alabama in June, so OAT is high enough to push my personal temperature limits with the cowl door shut. However, it does illustrate the effect of aero cleanup on an -8:...
My -8 spent last weekend parked in a hangar with a Harmon II. When you get 'em side by side, the -8 looks pretty chunky.
Or maybe it's just that a Rocket driver's wallet has been lightened so much
Considering the effect of the above standard altimeter setting, the fourth example has a pressure altitude of 10,390 ft, and an ambient pressure of 20.67 in HG. 174 kt CAS results in a ram pressure rise of 1.47 in HG. Add the ram pressure rise to the ambient pressure, and we have 21.74 in HG at the entrance to the air inlet, not considering the pressure increase due to the prop (the pressure behind the prop must be somewhat above ambient, but the pressure distribution isn't going to be even across the whole prop area, so I'm not sure how to estimate what it would be at the air inlet).Vern may have been giving you a little prod there, Bob. I doubt you can get those MP numbers through an E-0995 cone filter. In fact, they're not very realistic with an unfiltered intake.
Consider your 4th example, 10,500 ft, 210 KTAS, 51F OAT, 2490 RPM. Static pressure is 20.19 Hg. Assuming a 4" diameter intake and 100% VE, intake Q works out to be 0.9 Hg, thus total pressure at the face of the fuel control body is 20.19 + 0.9 = 21.09 Hg. MP is measured at the tail end of one cylinder's intake tract, after the carb loss and tract frictional losses. Carb loss for the RSA-5 alone is roughly 10" H2O, or 0.736 Hg, so 21.09 less 0.736 = 20.35 Hg, best case....but the EIS is reading 21.3. Naa......
Run the same numbers for the RV-8/IO-390 example. We have 7500 ft, 191 KTAS, 52F OAT, and 2420 RPM. It has a 4" intake ring. Assume 100% VE, so intake Q is 0.94. Static is 22.66, so total is 23.6 Hg. I have a filter loss, a carb loss (less than yours, as it's an FM-200), and a tract loss. The end measured MP is 22.5. If the MP sensor is assumed to be accurate, I have a total intake loss of 1.1" Hg between the face of the FM-200 and the MP tap on cylinder #3. I suspect my MP sensor might be a little low. Need to do a static check at annual, which is due now anyway.
The above assumes no separation loss inside the intake. And as always, check my numbers.
Considering the effect of the above standard altimeter setting, the fourth example has a pressure altitude of 10,390 ft, and an ambient pressure of 20.67 in HG. 174 kt CAS results in a ram pressure rise of 1.47 in HG. Add the ram pressure rise to the ambient pressure, and we have 21.74 in HG at the entrance to the air inlet, not considering the pressure increase due to the prop (the pressure behind the prop must be somewhat above ambient, but the pressure distribution isn't going to be even across the whole prop area, so I'm not sure how to estimate what it would be at the air inlet).
So, Bob's 21.3 in HG MP is somewhat plausible. I know that my RV-8 with Van's standard snorkel air inlet achieves MP above ambient, based on comparing the MP during a full power pass down the runway to the MP seen with engine stopped on the ground. I get about 0.9" above ambient at 185 kt CAS based on the data I've recorded from the engine monitor and EFIS.
So the SOP for testing is a full throttle low approach at the local airport? Cool.
Considering the effect of the above standard altimeter setting, the fourth example has a pressure altitude of 10,390 ft, and an ambient pressure of 20.67 in HG.
Actually, the 185 kt point was checked at roughly 1000 ft AGL, so I had the same MP that I had seen on the ground a few minutes before with engine stopped. Keeping the MP the same avoided any question of MP indication calibration. The ambient pressure was calculated starting from the pressure altitude.
That's because I made a typo. I should have typed 10,390 ft pressure altitude = 20.267 in HG. Add 1.47 in HG for ram pressure, and you get 21.74.Thanks Kevin, I didn't consider pressure altitude. That aside, can you help me understand your static pressure figure (20.67)? The standard atmosphere references suggest it's a bit high for 10,390 ft.
True, and I hadn't considered the impact on the pressure. That would certainly decrease the potential ram pressure available.The difference in dynamic pressure values is because I'm calculating Q for the delta between airbox inlet and outlet velocity. Remember, it's not a dead end pitot. Method later; gotta get to the office.
That's because I made a typo. I should have typed 10,390 ft pressure altitude = 20.267 in HG.
That would certainly decrease the potential ram pressure available.
I did a very quick back of the envelope calculation using the 10,500 ft case in Bob's fourth picture.Is there any chance that the propellor is acting like a very loose clearance supercharger and providing the mysterious higher than calculated or logical MP values at speed?