Well, we are just a month past first flight, and two of these weeks we were out of town. We?ve had a couple of ?No Fly? days due to weather, but we now have 33 hours on the airframe, and I can share a few test results.
We?ve expanded the speed envelope from a flaps-down stall of 50 knots IAS to the redline of 183. We did a few limited TAS excursions (a couple of knots) above that in a smooth-air descent, but will stick with the design redline ? I have no desire to test the flutter limits beyond Van?s engineering. Stalls are normal for an RV ? power off, it breaks sharply, but honestly, and recovers instantly when you release back pressure. Holding it in an incipient stall with power on gives a fair amount of tail ?rattle? (it?s a metal airplane), but I found nothing loose or damaged afterwards ? it?s just a little noisy.
One turn spins left and right were quick, but normal, with a steep entry. We?ll explore spins more in future tests. I don?t think this will be a favorite spinning airplane ? it loses altitude pretty quick. I?ll go get a Cub for lazy spins?.
Max G?s demonstrated have been 4.8?..if I?m going any higher than that, I?ll have to wear squeeze pants?.
Best rate of climb airspeed appears to be between 95 and 100 knots IAS at sea level. A timed climb at 125 TAS from 3,000 to 12,000 took 6:30, for an average ROC of 1384 fpm. That was a ?Cruise climb to keep CHT?s below 400. Max ROC we?ve seen steady state (after the zoom) down low is in excess of 3,000 fpm between 2,000? and 3,000? (msl). Speaking of cooling, it IS winter, but the oil temp hasn't gone above 180, even in extended slow flight. CHT's are limiting for climb after awhile - but do just fine at a 1,500 fpm cruise-climb at 120 KTAS.
I took the airplane up to 17,500? today where it was still climbing at 500 fpm at cruise-climb of 120 KTAS. I leveled off (no IFR in Phase 1) and let the airplane stabilize at full throttle (leaned to peak) and 2500 rpm. The EFIS showed this as 50% power, with a fuel flow of 5.7 gph. This gave a TRUE airspeed of 165 knots. There was 35 knots of wind up there, and when I pointed the nose downwind, that gave a groundspeed of 200 knots, with a mileage of?.yeah, it was ridiculous!).
Coming down from altitude requires a considerable throttle-back, or you?re over the TAS redline pretty quick.
CG has been tested to the aft limit, and right on the line, pitch stability is neutral and undamped ? yet the airplane is easier to land in that condition than an aft-loaded RV-8. With normal loading, it is positively perfect at all speeds and conditions.
Louise has been busy with cruise performance testing, and is reducing the data when she has the chance. I haven?t tried a flat-out max speed run at full throttle on the deck, but based on what I have seen, I expect it to be about 183 knots ? redline.
Aerobatics ? I?ve done all the rolls (except snaps), loops, Cubans, Immelmans, cloverleafs, Split S?s?well, pretty much all of the stuff I would expect this sport acro machine to do. It?s really got the power to do vertical rolls and it?s so nice having the Half-Raven system to keep from spewing oil all over the belly.
I?ve done a fair amount of avionics testing to make sue the major stuff works. After squashing a few bugs here and there, everything seems to work ? G430 is great for GPS, VOR, and ILS work ? approaches are great ? coupled or uncoupled. The GxPilot is doing great, and plays very well with the G3X ? which is also outstanding. I?m still working through all of the A/P modes, but it is pretty cool to give it a crossing altitude at a fix and a desired rate of descent ? then watch it start down at the right time. We?ve done one cross-country to College Station (in our test area) to see how it is in cruise ? and it?s great! It?s pretty easy to get it dialed in for 70% power and 7 gph at a few thousand feet ? that?s a nice four hours to dry tanks.
On the maintenance side, we?ve had one instance of cracking on the little extension of the right lower flap skin that ?underlaps? the fuselage. The flap skin is pretty thin, and I expect that the unsupported piece is flexing in the breeze when deployed. I?ll probably add a doubler before it goes to paint. We added a small rudder trim wedge until I engineer and install an active trim tab (or don?t?..). the right brake seems to be evaporating brake fluid?.have had to pump it up once in 33 hours, but can?t find any sign of the fluid going anywhere. Little stuff ? nothing major.
So onto finishing up Phase 1?then we?ll be free to explore a bit more ? need to take it on a trip to the paint shop to get Grady looking at ideas for us?.
We?ve expanded the speed envelope from a flaps-down stall of 50 knots IAS to the redline of 183. We did a few limited TAS excursions (a couple of knots) above that in a smooth-air descent, but will stick with the design redline ? I have no desire to test the flutter limits beyond Van?s engineering. Stalls are normal for an RV ? power off, it breaks sharply, but honestly, and recovers instantly when you release back pressure. Holding it in an incipient stall with power on gives a fair amount of tail ?rattle? (it?s a metal airplane), but I found nothing loose or damaged afterwards ? it?s just a little noisy.
One turn spins left and right were quick, but normal, with a steep entry. We?ll explore spins more in future tests. I don?t think this will be a favorite spinning airplane ? it loses altitude pretty quick. I?ll go get a Cub for lazy spins?.
Max G?s demonstrated have been 4.8?..if I?m going any higher than that, I?ll have to wear squeeze pants?.
Best rate of climb airspeed appears to be between 95 and 100 knots IAS at sea level. A timed climb at 125 TAS from 3,000 to 12,000 took 6:30, for an average ROC of 1384 fpm. That was a ?Cruise climb to keep CHT?s below 400. Max ROC we?ve seen steady state (after the zoom) down low is in excess of 3,000 fpm between 2,000? and 3,000? (msl). Speaking of cooling, it IS winter, but the oil temp hasn't gone above 180, even in extended slow flight. CHT's are limiting for climb after awhile - but do just fine at a 1,500 fpm cruise-climb at 120 KTAS.
I took the airplane up to 17,500? today where it was still climbing at 500 fpm at cruise-climb of 120 KTAS. I leveled off (no IFR in Phase 1) and let the airplane stabilize at full throttle (leaned to peak) and 2500 rpm. The EFIS showed this as 50% power, with a fuel flow of 5.7 gph. This gave a TRUE airspeed of 165 knots. There was 35 knots of wind up there, and when I pointed the nose downwind, that gave a groundspeed of 200 knots, with a mileage of?.yeah, it was ridiculous!).
Coming down from altitude requires a considerable throttle-back, or you?re over the TAS redline pretty quick.
CG has been tested to the aft limit, and right on the line, pitch stability is neutral and undamped ? yet the airplane is easier to land in that condition than an aft-loaded RV-8. With normal loading, it is positively perfect at all speeds and conditions.
Louise has been busy with cruise performance testing, and is reducing the data when she has the chance. I haven?t tried a flat-out max speed run at full throttle on the deck, but based on what I have seen, I expect it to be about 183 knots ? redline.
Aerobatics ? I?ve done all the rolls (except snaps), loops, Cubans, Immelmans, cloverleafs, Split S?s?well, pretty much all of the stuff I would expect this sport acro machine to do. It?s really got the power to do vertical rolls and it?s so nice having the Half-Raven system to keep from spewing oil all over the belly.
I?ve done a fair amount of avionics testing to make sue the major stuff works. After squashing a few bugs here and there, everything seems to work ? G430 is great for GPS, VOR, and ILS work ? approaches are great ? coupled or uncoupled. The GxPilot is doing great, and plays very well with the G3X ? which is also outstanding. I?m still working through all of the A/P modes, but it is pretty cool to give it a crossing altitude at a fix and a desired rate of descent ? then watch it start down at the right time. We?ve done one cross-country to College Station (in our test area) to see how it is in cruise ? and it?s great! It?s pretty easy to get it dialed in for 70% power and 7 gph at a few thousand feet ? that?s a nice four hours to dry tanks.
On the maintenance side, we?ve had one instance of cracking on the little extension of the right lower flap skin that ?underlaps? the fuselage. The flap skin is pretty thin, and I expect that the unsupported piece is flexing in the breeze when deployed. I?ll probably add a doubler before it goes to paint. We added a small rudder trim wedge until I engineer and install an active trim tab (or don?t?..). the right brake seems to be evaporating brake fluid?.have had to pump it up once in 33 hours, but can?t find any sign of the fluid going anywhere. Little stuff ? nothing major.
So onto finishing up Phase 1?then we?ll be free to explore a bit more ? need to take it on a trip to the paint shop to get Grady looking at ideas for us?.