Flight test: Card 1

 Since more than 830 RV-12s are flying, quite a lot of knowledge has been accumulated regarding what to expect during flight test.  Van's provides at the end of the PAP (Production Acceptance Procedure) five flight test cards to accomplish Phase I.  It's a task-based approach rather than hours-based and I'm pretty much following what's laid out in the PAP.  It's done just like the rest of the PAP, that being check boxes followed by a description of the task (83 check boxes for the first test card alone).  Some tasks are simply yes/no, OK/not-OK things, others require numbers to be recorded.  The data logging system built into the Dynon HDX helps tremendously.  The system records all flight and engine parameters many times per second which are then downloaded to a thumb drive after each flight.  

All flight testing is set up to be done solo at a specific total weight.  Accurately observing and recording numbers would difficult while also flying the airplane.  Thank you Dynon for providing this terrific data logging tool.  The FAA now allows, as discussed in the previous post, an additional qualified pilot to assist with Phase I, but so far I'm feeling the urge to keep doing it solo.  For some of the tasks I may want a helper, an example being calibration of the AOA gage which requires pushing a button on the EFIS at exactly the stall break while keeping the wings level with rudder.  We'll see.

Before getting into the actual flight test, here are a couple of additional thoughts about the first flight.  I've done eight flights so far (about 11 hours on the Hobbs) and I've gained some perspective.  Here's what I felt I had just done immediately after the first flight:

That's actually Chuck Yeager in a rocket-assisted F-104.  Here's what other people probably thought I had done on my first flight:

The first of the five test cards checks to see that all the sensors, instruments and systems are functioning properly.  Basic flying qualities are evaluated including trim and straight-ahead 1g stalls.  Frankly, considering the complexity of the systems, I'm surprised that everything worked perfectly and the airplane flies so damn well.

After reading the write-ups other builders have done detailing their flight tests, I was fully expecting to have a "heavy" wing as most people do to varying degrees. That's a tendency to roll one way or another with the ball centered and hands off the stick, requiring corrective stick force to counteract the rolling tendency.  No heavy wing.  The airplane also stalls straight ahead with no tendency to fall off on a wing.

Power-off 1g stalls were done with no flaps, half flaps and full flaps.  Because of the surprising numbers I am seeing in the cockpit (confirmed by the data logs) I repeated the stalls in each configuration multiple times on multiple flights.  According to a table in Section 5 of the POH, indicated airspeed and calibrated airspeed (corrected for instrument error) are the same.  Based on my real-world experience, I find this hard to believe.  Theoretically, a Pitot tube would produce about 3.5% error at the AOA seen at stall (~15 degrees) but I've seen larger errors in the lab.  Van's does bevel the end of the Pitot in order to mitigate this, so maybe it's true.  I just had a discussion with a Van's techs support guy at Oshkosh, and he agreed with me and said he'd check.  Strangely, just under the table in the POH showing no difference between indicated and calibrated airspeeds, the very next table shows a difference of about 4 knots between indicated and calibrated airspeeds but with indicated being higher than calibrated for stall speeds in all three flap configurations at a gross weight of 1050 lbf!  This would make my numbers even more amazing. Solo with full fuel, i'm right at that weight.

Anyway, even with a few knots error I'm surprised with the numbers I'm seeing.  Prior to flying my airplane, I had done stalls in other RV-12s, but it was always with a passenger.  For my airplane, built light (735 lbf empty weight), a passenger can easily be 25% of that, having a substantial effect on performance.

Solo, with about 110 lbf of fuel, I'm repeatedly seeing an indicated stall speed of 40 knots with no flaps and 35 knots (!) with half flaps.  With full flaps the number is a bit higher, probably because the nose is bobbing up and down and never reaching steady state.  The static ports are on the sides of the fuselage a few feet behind the aft edge of the canopy and may be in the turbulent wake from the separated flow at the wing root  

Landing, full flaps do add noticeable drag.  Half flaps are apparently magic in this airplane and that's the way I land unless I'm high on final -- something I prefer, slipping off any excess altitude.  This airplane will sink like a Cherokee (what I learned to fly in 57 years ago!) when slipped with full flaps.

The pic shows me sharing the runway with a bird on short final.  My hangar is at Vance Brand Airport (KLMO) in Longmont Colorado, elevation 5040 feet msl.  One of the tasks on the first card involved pushing the nose over until I had 120 knots indicated.  Starting at our field elevation and climbing a few thousand feet to do the tests, my density altitude has typically been over 10,000 feet.  Before doing this, I wondered how close I'd be to Vne (never exceed speed, no doubt based on flutter margins).  Many pilots I've known think Vne is indicated airspeed.  That's a good way to become no longer counted among the living.  Vne is true airspeed, 136 knots on an RV-12.  Fortunately, my Dynon HDX displays true airpseed (along with density altitude) so I kept a close eye on it as I did this task.  As I slowly approached the prescribed speed, at an indicated speed of 119 knots I bagan releasing forward force on the stick.  The computer screamed in my ear "Overspeed, Overspeed."  The data log showed I had reached a true airspeed of 136.1 knots.  I'd like to never hear that again.

Oshkosh 2026  I just returned from my 37th pilgrimage to aviation Mecca.  Although there was a record crowd (around 3/4 million people) it was a bit atypical.  As usual, I got there on Sunday (usually one of the best days for watching arrivals) but smoke from Canadian wildfires kept the airplane traffic low until Wednesday.  It was still, as always, a sensory overload.  Our NASA administrator, Jared Isaacman, flew his personal Mig 29 in.

His personal T-38 was parked beside it.  Looking at his accomplishments, I'd say he's an amazing guy.

First flight

 Incredibly, I started this build at my home on beautiful Badin Lake east of Charlotte, NC in October of 2011.  This bird flew the nest at my home airport in Longmont, CO on May 12th 2026, so I'm hereby claiming the record for the longest build time for an RV-12: 14.5 years.  Time flies.

First flights of aircraft licensed in the experimental category have historically had a comparatively high accident rate, and it's easy to see why.  In addition to physically flying the airplane, a solo pilot is keeping a sharp eye on the engine instruments (oil temp, oil pressure, fuel pressure. left and right cylinder head temps, left and right exhaust gas temps) and on the flight instruments.  After all, this airplane has never been in this situation before, pitched up at this angle at full power for this long.  Did I do all the wiring correctly?  Did I crimp all the fittings on wire ends well?  Did I adequately tighten all the fittings on oil, gasoline and water (yes water) lines?  It's a mental load which can distract from most important task: flying the airplane.

A few years ago the FAA actually did a wise thing by instituting the "additional pilot" program, whereby a second, qualified pilot with experience in that make and model airplane can accompany the builder pilot on the first flight, sharing the work load.  From what I've read, the first-flight fatal accident rate is now zero since the program was started.  My fearless friend and CFI Bill Snodgrass accompanied me.  Bill has over 1600 hours in RV-12s and is intimately familiar with how they should look, feel, sound and smell (and maybe taste).  I had planned to fly his RV-12 several times in the days leading up to the first flight in mine, but ended up not having flown at all for four months prior to the first flight.  The rust on my piloting skills was evident.  I had flown his plane for 20 or so hours in the previous year, so I was not completely uncalibrated to the RV-12, but I should have flown just prior to my first flight.

There are two schools of thought on first flights.  Some say an actual test pilot should be used because the builder is too heavily invested (emotionally and financially) in the airplane and might try to protect the airplane rather than save himself in the event of an emergency.  To me that would be akin to hiring a professional to stand in for you on your wedding night.

The pic above shows the airplane before the flight.  I know it's considered bad luck to photograph a flight before departure.  I figured if I made a smoking hole in the ground the NTSB could look at this pic and see that all the pieces were there.

The actual flight went well, no heavy wing, all instruments showing what I expeccted.  Rather than start on the first flight-test card, we decided to shoot four landings to a full stop, then pull the top cowl to look for leaks (none found).

Here's the after pic with the requisite RV grin.  It's been two days now and I think I'm still smiling.

I had planned to start the formal flight test yesterday but the wind didn't cooperate.  Phase I flight test will be entirely task based rather than time based as was typical in the past.

The Spousal Unit (my beautiful and talented wife, Karen) had given me strict instructions to not tell her when the first flight was going to occur in order to minimize her worry.  This was hard to accomplish without outright lying.  The day of the flight it went like this.  Her: "You're not going to fly today are you?"  Me: "Actually, I'm thinking about flying tomorrow."  That wasn't a lie.  I was, indeed, thinking about flying tomorrow but planning to fly today, also.

Off topic: Weird Colorado weather

We've had a dry year here on the Front Range, with snow totals and mountain snow pack about 1/3 of normal.  However, a few days ago we had eleven inches of snow over a two-day period, which then melted entirely within 24 hours.  Snow in May seems strange to this southern boy.

Airworthiness Certificate

 The final hurdle in this process -- a process which took 15 years and certainly involved blood (several #30 and #40 holes in various fingers and other blood-letting feats), gallons of sweat, and a fair amount of money -- is the Airworthiness Certificate.  Getting this certificate involves, among other things, an inspection by the FAA itself or by a person designated by them called a Designated Airworthiness Representative (DAR).  If the people from the FAA do it, it's free but apparently impossible to schedule.  If a DAR does it, it's expensive but can be done at your convenience.  I had an excellent DAR, Brad Roon, who charged $1000.  Horror stories abound from other builders I know who have gone through the process, so I consider myself lucky.

For the inspection, all cowls and inspection plates must be removed and certain bits of paperwork must be available. The required on-hand paperwork includes aircraft registration, weight and balance calculations, a complete list of service bulletins with dates showing completion, and a few other documents.  Brad provided a list of everything he wanted to see.  He did a very thorough physical inspection of the entire airplane, which made me a bit nervous, but was what I wanted.  I was confident that all was good because I had a superb EAA technical counselor (Dan Berry) doing periodic inspections as everything went together.  Dan was picky (to put it mildly) but, again, that's what I wanted.  After all, this machine, which started out as a collection of parts, will soon carry me into the sky.

Prior to the DAR visit, the on-line AWC application must be completed on the FAA website.  This is an unbelievable PITA, what you would expect, I suppose, from a government website.  Many documents must be uploaded there, including the Maintenance Manual, the Flight Training Supplement and the Pilot Operating Handbook.  Each of these is over 100 pages, and they want the actual documents, not a link to the documents.  I'll bet you $1000 to a dime that no one at the FAA looked at these other than to see that they were there.

One of the things you submit is a request for a test area, a box specified by lat-long coordinates, within which you're restricted for the Phase I flight test.  I photocopied part of a sectional chart for that and included it in my application, with my requested test area marked in red.

What the FAA granted me was much more generous: from Boulder north to Wyoming and from the Rocky mountains east beyond Fort Morgan.  Brad asked me how much flight time I needed for phase one.  For an E-LSA it can be as little as 5 hours rather than the usual 40 hours for EAB.  I told him 10 hours.  No doube it'll take longer.  Phase I flight test as it appears in the PAP provided by Van's is task based rather than hour based.  I'll describe it as it happens.

Another thing that is issued in addition to the Airworthiness Certificate is a document listing the Operating Limitations for the aircraft (OpLims).  These are requested by the DAR and approved by the FAA.  They give conditions under which the airplane must operate: pilot certificates required, what can and can't be done with the airplane, etc.  Interestingly, even though aerobatics are prohibited in the RV-12 by Van's, the OpLims say only that any aerobatics to be done must be demonstrated during phase one flight test.  Hmmm. Also, a lot of verbiage is devoted to talk about not having external things on the aircraft that can be jettisoned during flight.  That lets out any bombing runs.

So with Airworthiness Certificate in hand, all that's left is to re-install all the cowls, covers and plates, then go fly.

Off topic (sort of)

Here's what happens when you're old and you've hung around airplanes since grade school.  Hard to believe it's been 55 years since I got my license.  Time flies.

PAP Section G6-1: Dynamically balancing the propeller

After syncing the carbs I was less than pleased with the amount of vibration present, especially at low RPM. This being the case, I decided to deviate from my previous plan and do the DynaVibe deal before first flight.  I had planned to put this off until after Phase 1 flight test, as many people do, and fly the plane over to Akron, CO to a shop where others I know had done this with satisfactory results. 

The Mothership recommends doing it before first flight, however.  A member of my local EAA chapter 648, Rick Hall, owns the most expensive version of the DynaVibe balancer and offers it, along with his expertise, free of charge to chapter members (he did accept a bottle of Beefeater gin).

Using this device requires attaching three things to the engine: an accelerometer, preferably as close to the engine centerline and as near the prop as possible (shown here nearest the prop hub with the single black wire), a piece of special reflective tape to the back of one prop blade, and a laser pulse counter (the yellow device to the right).  The laser and reflective tape measure prop RPM.  The tach in the airplane shows engine RPM.

The engine is run at low RPM (2500 in the case of a Rotax 912), then up to cruise power (5200 with the airplane static, depending on how you pitched the prop) where the engine will live most of its life.  The DynaVibe then gives an angular location for the temporary stick-on balance weight and the mass of the weight.  The DynaVibe assumes the weight will be on the perimeter of the rear bulkhead for the spinner.  If for some reason the weight must be attached at a different radial location, a simple calculation allows the new mass value to be determined (r1 * m1 = r2 * m2).

I tied the tail to Rick's pickup truck since I'd had the airplane jump the chocks on a previous full-power run-up.  When that happened I feared I had set the prop pitch too fine, thereby producing too much static thrust.  My fears were allayed when I saw the correct static RPM (5200) at rull power.  On one full-power run I did throw off one of the stick-on weights, heard it hit something over the roar of the engine, but could never find it.

This process stretched over two days (due to starting mid-afternoon) but could have been done in two hours if I had been prepared.  I was not familiar with where and how the brackets for the accelerometer and laser attached to the engine.  Turns out I needed two M8 bolts which I didn't have.  A trip to the aviation aisle at a nearby Home Depot solved that problem but wasted time.

The picture at right shows the temporary stick-on weights on the aft face of the spinner bulkhead.  It was necessary to remove the paint to keep them attached at high RPM.

Van's warns against succumbing to the temptation to attach the permanent weights to the existing screws which attach the spinner to the bulkhead.  Instead, a new hole should be drilled in the bulkhead face and bolts and washers should be used to match the weight of the temporary ones.  Being an anal engineer, I calculated the weight of the aluminum removed by the drill (0.1 grams) and ground the required metal off the washers to get the matching weight.  The required weight was 13.1 grams (yeah, I know that grams is a unit of mass, not weight, but irritating though it may be they express weight in grams in Europe where the Rotax is made).

I was initially worried that the existing nut plate or rivets would interfere with the bolt head or nut of the permanent weight, but it turned out to not be a problem.

Shown first is the aft face of the spinner bulkhead, then below it the forward face.  I used large diameter washers for the AN3 bolt to keep the stack short.  Ideally, the DynaVibe would be used again to check the final balance with the permanent weights but this wasn't done.  I'm confident it's good.