Another RV-10 Site
Flight Testing

What doesn't kill you makes you stronger.

RV-10 Flight Testing

This page documents the Phase I flight testing and flight test data of my RV-10, N961M.....which I built myself!!! I have also documented a number of my procedures for flying the airplane.

Paper to make an airplane fly
Of all the paper work need to make an airplane fly, I've listed the most useful below for you to download and use as a template for your own airplane. You can right click a document and select save-as to download directly to your computer.

Weight and Balance
This is the weight and balance submitted to the FAA. It shows that when flying solo, I am up against the forward CG limit. I put 50 lbs of weight in the baggage compartment to move the CG back an inch.

Checklist
Checklist specific to N961M. Print, fold pages in half and then bind. This will be updated during the test program.

Flight Test Plans
These are based on FAA Advisory Circular 90-89A with the addition of engine break-in and determination of the airplane's drag polar curve. I believe the best way to determine most V speeds is from the drag polar.

Pilot's Operating Handbook
Pilot's Operating Handbook specific to N961M.

Drag Polar Presentation
This is a presentation I gave to EAA 228 on how to measure an airplane drag polar curve.

Its better to be on the ground wishing you were in the air than in the air wishing you were on the ground.

I am confined to my test area for the first 40 hrs of test flying. After that I am free to move about the country. Test areas are to be over uninhabited places. Since Arizona is mostly uninhabited I have a pretty generous test area spanning from Phoenix to Tucson. This has worked out well as I am able to do my aerodynamic testing up and down the valley. I also have access to ILS and GPS approach systems in my area for EFIS training and integration. And most importantly, I am able to pick from a couple of less expensive fuel options outside of the Phoenix area.


My Favorite Cartoon


My Test Area

Flight #

Hours

Notes and Data

1

0.9 hrs

First Flight April 15, 2011
Tuesday April 12, 2011, the airplane was signed off by the FAA. After that I had to switch gears from FAA paperwork to getting the airplane back together for first flight. Reassembly took about 6 hours and I managed to reset my engine computer Thursday night and had to reprogram all my settings on Friday. By Friday morning things were coming together and the airplane was fueled and the left tank fuel sensor was calibrated on fill up. My airplane-pilot-weather self evaluation was all go for flight. I came home to catch a couple of Z's and then back to the airport in the afternoon for a 5 PM flight.

Start up and taxi went smoothly. Engine run up was normal, take-off clearance, throttle up, accelerated to 60 kts in about 12 seconds much like my Corvette used to do. Was airborne and immediately started to smell something burning. Fully expected the tower to radio me that I was trailing smoke but no radio call came. I figured my cowl wasn't on fire from the exhaust (back of the mind concern) or that would make a tremendous amount of smoke. I was in a 95 kt climb and started my first turn. The smell subsided and I attributed it to the new engine or the exhaust heating for the first time. In a short time I was at 3500', reduced power to 70% for engine break in and accelerated to 130 kts indicated cruise airspeed. Ground speed was probably up around 145 kts.

The airplane flew perfect in roll, only required a little trim (which I didn't activate until I was at altitude) in pitch and a whole lot of left rudder due to the high power I was running with. Circling overhead the airport such a high speed took constant attention and maneuvering. During the short periods of level flight I was recording cylinder head and exhaust temperatures from the flight computers and working through my first flight test plan. I had one cylinder running at 406 degrees that I kept my eye on. I stayed up for almost an hour and then came in for a textbook landing.

Post flight I pulled the cowls and center tunnel covers for inspection and no leaks were found. The only squawk so far is that I need to add a rudder trim tab. Everything else seems to be working as planned.

Approach.

First Landing.

2 to 7

12 hrs

Flight 2 to 7 (Engine Break-in Flights)
Following my test plans pretty much went out the window by flight 2. During engine break-in, the engine must be run with 65 to 75% power. At this power level, the airplane is cooking along at 130 to 140 kts. It is well above maneuvering speed, Va, and pretty much impossible to conduct any aerodynamic testing. The only things I have been able to do so far is to stop the auto-pilot from trying to kill me, get the two displays to play nice with each other, and get the GPS's talking to the flight computers.

I've been pulling the cowls after every flight and inspecting all the fuel and oil hoses. Also after each flight there are a few things to research about the avionics and squawks which need resolution. For example, the prop governor needs adjustment on the ground for max rpm and can only be tested in a take-off. I've also been making adjustments to a rudder trim tab I added after first flight.

I've been monitoring my cylinder head temperatures (CHT) and taking data at about 0.5 hour intervals. They were hottest on first flight and then steadily cooled down. I've been running a little more power in flight 3, 4,5 and alternating between 65 and 75% power. The higher power setting pushed the temperatures back up and if I lean the mixture the temperatures also go up. The engine has been drinking 20 gal/hr at these power setting and I am trying to lean as much as I can without driving the temperatures too high. I've plotted the CHT data and have noticed that cylinders 2, 5 and 6 run at least 20 degrees hotter than 1, 3 and 4. I can understand 5 and 6 running hotter since they are in the back, but why 2? Turns out that cylinder 2 has been the hottest with other builders too. I tried adding baffle material around the motor mounts in the rear shroud to see if that would have an effect on cylinder 5 and 6 but it did not. Since I can keep temperatures under 400 deg F through power management, I am not going to worry about it right now.

I noticed that my SL-40 has a tremendous amount of background noise when I key the mic. I have lowered the mic gain but it is still somewhat noisy. I measured the acoustic background in the RV-10, my Piper Dakota and my Chevy Silverado at highway speed to see the difference.

  • Chevy Silverado: 66 dBA
  • Piper Dakota: 88 to 90 dBA
  • Andresen RV-10: 98 to 102 dBA

Oil consumption dropped dramatically after the first two hours and is fairly stable at 0.13 qts per hour. That is a little more than a quart per 10 hours and I think that is great. Based on the oil consumption I am going to declare engine break in complete at 15 hrs and start aerodynamic testing.

Superstition Mtn.

Displays in Flight.

CHT Chart

Oil Consumption Chart

8 to 10

19 hrs

Flight 8 to 10 (No wheel or leg fairings)
Now that I have not gone up in a fire ball after 15 hours of flying, I am feeling a little more confident in the airplane. I still dress for the possibility of an in flight fire which means I am roasting during taxi and when on the ground as Arizona spring is here in full force. I did find a slight fuel seepage in the hose fitting that connects the throttle body to the fuel distributor (spider). It is a hose that comes with the engine and I will order a new one from Precision Hose Technologies.

I started the flight tests to determine the drag polar curve for the airplane. From that, I will determine all of the V speeds except stall speeds which have to be done directly. The curves shown below are for four test flights and have curve fitting applied. The EFIS reads out engine power which I record and convert to thrust. I then record my fuel level at test time so I know total weight. Since weight=lift and thrust=drag, I can compute the L/D ratio. I know when I say weight=lift, I am neglecting tail down force and if I get bored enought I may include it in the calculation but I don't think it introduces much error.

Based on my measurements so far, the RV-10 has 75 lbs less drag in flight than my Piper Dakota. The RV-10 has a glide ratio of 8.7 while the Piper Dakota glide ratio is 7.7. These comparisons are for the RV-10 without wheel fairings and the Dakota with wheel fairings. I also noticed that if I trim for the same indicated cruise airspeed as the Dakota, I am buring only 10 gph versus 13 gph. That quite a bit more fuel effeciency

Thrust for Level Flight

Lift to Drag Ratio

NA

8 hrs

Break for Maintenance
I have moved all maintenance, tweaks and fixes to their own page. This page will be completely dedicated to RV-10 aerodynamics. The link for the new maintenance, tweaks and fixes page is here: Phase I Maintenance

11 to 13

26 hrs

Flight 11 to 13 (With wheel fairings)
People have told me that they have become bored during their fly off and I have not found that at all. I've been running my test period like a NASA research program and it has kept me pretty busy in the air. I still have climb performance and procedure development to do.

Stall Testing
These speeds were determined over several stall iterations and over a couple of flights. With the flaps in the -3 and 0 degree positions the stall was very gentle. I could pin the stick back into an aggrevated stall and maintain level wings with the rudder and execute a falling leaf maneuver. With 15 and 30 degree flaps, the stall was more pronounced and the airplane would roll right. This was a surprise to me becasue every other airplane I have flown broke left except for the SNJ-6 which broke right. The table below gives the stall speed at my test weight of 2200 lbs and the speed scaled for max gross weight. I also included approach speeds(1.3 times the stall speed)for each of the configurations and weights. I plan on trying some cross-controlled stalls to see how the airplane behaves but haven't gotten to it. Now that our Arizona temperatures are over 100 degrees, the air has been getting rough from thermal turbulance by 10 AM and I have limited time in the early morning for flight testing.

. Flap Position
Speed Weight -3 deg 0 deg 15 deg 30 deg
Stall 2200 lbs 64 KIAS 62 KIAS 54 KIAS 52 KIAS
2700 lbs 71 KIAS 68 KIAS 60 KIAS 58 KIAS
Approach
1.3 x Vs
2200 lbs 83 KIAS 80 KIAS 71 KIAS 68 KIAS
2700 lbs 92 KIAS 89 KIAS 78 KIAS 75 KIAS

Aerodynamics (With wheel fairings)
I repeated the drag polar testing that I originally did with no wheel fairings. I am glad it is over as it took almost 2 hours per test run and these charts took multiple runs. The result is that the wheel fairings reduced drag by 26 lbs. The best glide ratio increased from 8.7 to 9.7. I also noticed that the effect of -3 deg and 0 deg flap became almost indistinguishable. I retested in flight and found that the 0 deg flap position only reduced speed by 2 or 3 kts. It takes less than one percent engine power change to make up for it so the difference was within the accuracy of my testing. So the in trail flap position adds a little more lift with an almost imperceptible increase in drag.

RV-10 Thrust for Level Flight

RV-10 Lift to Drag Ratio

RV-10 Power Required
This graph shows the power required for level flight with and without the wheel and leg fairings attached. The RV-10 picks up 10 to 15 knots (depending on power setting) with the wheel pants installed.

Cruise Performance
Using the data I collected for indicated airspeed versus power and the Lycoming engine performance charts, I generated curves for true airspeed, range and fuel economy of my RV-10.

RV-10 True Airspeed

RV-10 Fuel Economy

RV-10 Range, 0 min Reserve

RV-10 Range, 45 min Reserve

14 to 17

34 hrs

Flight 14 to 16 (Procedure Development & Climb Performance)
All that time spent doing Vspeed determination comes together here in procedure development. This section will contain my procedures for approach to landing, instrument approach, entering slow flight, rejected landing, etc. It will take a while to develop and document so this section will be getting updated for a while.

Warning: These procedures are examples only and their use my cause severe bodily injury, death, dismemberment, disfigurement, burns over a large percentage of your body, impotence (don't want that, do we?), hair loss, blindness, boob growth on men, senility and a host of other unspeakable bad things. Use these procedures as an example and develope your own procedures!!!

Take Off

Landing

Slow Flight

Approach Stall

Here are my procedures for setting up an off field landing or an emergency decent.

Off Field Landing

Emergency Decent

Density Altitude
26Jun2011, Due to the beautiful clear skies and bright sunny weather, flight testing will be a little slow. Temperatures over 110 deg F and humidity sky rocketing up to 23% means summer is here. I started climb performance testing this weekend at 0600 local. When I analyzed the data that I took between 3,000 and 4,000 feet MSL, the density altitude was 6,000 to 7,000 feet. I am pleasantly surprised to see that I can maintain oil temperature below 200 deg F, and CHT's below 400 deg F in this weather. If my oil temperature rises above 200 degrees F, I simply power back in level or decending flight for a little while and it drops. This is different from my Dakota where once the oil temperature climbed it took forever to get it to cool back down.

Phoenix June Forecast

Today

Sizling Hot

Tomorrow

Damn Hot

The Next Day

Freaking Hot

The Day After That

Scalding Hot

RV-10 Climb Performance
I've had the toughest time collecting climb performance data. The climb to altitude data came out OK but my climb performance curve that is used to determine Vy and Vx was very elusive. I'd run a few test flights and every time have come back with what looks like random data that does not hold up to analysis. The trick to getting good data was to do two test runs on reciprocal headings to negate the effects of winds aloft. Then average the data from the two directions. That was what finally produced the curve below.

It has been very hot here and even though I flew at 0500 local at an average altitude of 4,000', the density altitude was 6,500'. The climb speeds were then adjusted to sea level to make the pilot's operating handbook Vx and Vy entries.

RV-10 Climb Performance

RV-10 Climb at Altitude

18 to 19

41 hrs

Flight 18 to 19 (Instrument Procedures)
Here are my procedures for setting up a VOR, GPS WAAS and an ILS approach. These procedures are intertwined with your avionics and it seems like the auto pilot is getting a second chance at trying to kill me.

The Garmin 430W is capable of sending steering commands to the EFIS and autopilot. This is different from point to point steering and is needed to fly the procedure turn under command of the GPS. The Grand Rapids EFIS must be updated to the latest software version to get this to work.

RV-10 VOR Procedure

RV-10 ILS Procedure

RV-10 GPS WAAS Procedure

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Phase I Complete!!
I am now free to move about the country!! It's a sense of accomplishment to be done with Phase I testing. I think I made the most of the time and have a good sense of the aircraft's performance. My plans from here are to take some friends for rides and then get it ready for the paint shop.

Don't forget to check out the Phase I maintenance page to see the squalks I fixed during the fly off: Phase I Maintenance

Mike Andresen
All Rights Reserved 2011 to Forever