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4 Jan 2011

Good progress on lots of fiberglass work.  Got the engine mount fairings finished and now need to bake them before installing.  The sump fairing is partially done and I did more glass layers and filling on tail weight.  I sparingly added Bondo to fill holes on the nose pant air dam.

It looks like the tail weight is well within W&B - even with the most aft CG situation.

6 Jan 10

More fiberglass progress.  Engine mount fairings aren't pretty, but I believe they will be functional.  I'll consider sanding and painting them later.  For now I put on a thin layer of resin and baked them in the oven at 250 degrees for 3 hours and installed them.  I'll check them after them next flight for damage or rubbing and also for effects of heat.

Had do major surgery on the main gear cuffs.  The trailing edges were not coming together well.  Anyway, after lots of filling and sanding, I only have another 8 hours of filling and sanding to go.  It will be interesting to see if they improve the airflow.

The tail weight is finished - for now.  Lots of filling and sanding on it, too.  Primer coat is on it and I need to get a thin nut to act as jam nut.  I may paint it with slick paint.

Got a call from Whelen today.  They repaired my power supply without charge and are shipping it free.  Customer service doesn't get much better than that!  I bought it from them about six years ago and had flown with it for 125 hours when it failed.  They said failed transistor and blown fuse.

The race in coming up soon so I need to get flight testing done to validate my work.  If there is no gain, then I'll race without the changes.

7 Jan 11        Today - 0.9        Total - 129.1

Got in two test flights today.  The first one was to test the effect of the two pound tail weight fastened to the tail tiedown point.  The second one was to test the effect of the Speedy Nose Pant Air Dam.  Nelson monitored both flights from the ground and observed the nose wheel for shimmy or ground contact.

The first takeoff was with great caution to make sure the pitch didn't increase too rapidly or the pitch become too sensitive.  Neither occurred.  As I did the W&B calculations again later, we could have had 10 pounds or more at that moment arm without a problem.  So, aircraft handling was not an issue.  The intent of the tail weight was to reduce induced drag by pulling down the tail using weight rather than aerodynamic force.  The 2 pound weight seemed to make very little difference.  The elevator horn protruded about 1/2" above the horizontal stablizer.  That is perhaps a bit more than before adding the tail weight - although that is difficult to determine for sure until the strobe power supply is reinstalled.  So, bottom line on the tail weight - little to no change.

The air dam is another story.  While test flying the tail weight, I did a WOT, 28.6 MP, 2670 RPM speed run at 1000' MSL.  The flight conditions were turbulent, so determining exact speeds was difficult, but it appeared that the speed averaged 185 KIAS.  A subsequent identical run 30 minutes later with the air dam installed showed a 1-2 knot increase - or an average of about 187.  With that encouraging info, I'll continue the work to design Speedy air dams for the main pants as well.  The main pants are a bit more critical regarding ground clearance, so careful planning is necessary.  Maybe the drag reduction of the three air dams combined will edge me toward 190 KIAS.

Today's flights were also the first ones with the engine mount fairings installed.  Post flight inspection showed the fairings were still firmly in place with no apparent contact with the exhaust pipes.  Air flow patterns from oil on the strut fairing and those burned on the exhausts show the downward air flow is quickly turned to flow directly along or slightly above the exhaust pipes.  I believe the exit air is reasonably aligned with the relative wind as it exits.  I have more plans for streamlining the air flow inside the lower portion of the cowling.

Tomorrow I want to finish the main gear Speedy Cuffs so I can test fly them next week.  I need to tuft both the nose air dam and the main gear cuffs and video them to evaluate the effect of my changes.

Looking at today's engine readings gives some insight.  The first flight parameters match the second flight very closely.  The only variables was 0.8 degrees of OAT and a difference in fuel flow of 1.2 GPH.  The higher fuel flow resulted in lower EGTs, but higher CHTs.  It is evident that when running at 1000' during the upcoming race that I must lean to 16 GPH or maybe a bit less.  The CHTs will run cooler if I do.

The appearance of a cooler EGT on #4 is likely due to a slightly different position in the exhaust pipe.  If a probe is just a 1/4" further down the pipe than another one, the flame may not reach it while the other one is within reach of the flame.  But, the CHTs should be reasonably close.  Cylinders 1,2, and 4 are evenly matched.  Number 3 is consistently well above the others by 40-43 degrees.  It is possible the probe is reading incorrectly, but switching them to check accuracy is not feasible.

First Flight

Second Flight

12 Jan 11

15 Jan 11            Today - 1.2            Total - 130.3

VERY Cool.  I now own the world's fastest RV-8A.  Today, at 1000' MSL, WOT, 2670 RPM, 29.1" MP, I got 193 KIAS in level flight.  I was hoping for 190 knots, so 193 was beyond expectations.

Last night I added "gap seals" using plastic vertical blinds attached with metal tape.  Good idea - bad technique.  They began fluttering shortly after takeoff and were causing control problems at 95 KIAS and, fortunately, the tape failed and they came off at about 105 KIAS.  I was relieved to see them rip off and scatter on the runway.  I nursed the airplane around the pattern for landing and Nelson helped me remove the remaining tape and retrieve the scraps from the runway.  I still believe gap seals will increase speed, but I will use more substantial material and fasteners next time.

I finished my Speedy Cuffs today and installed them not knowing what to expect in performance.  I was hoping for another knot or two.  They turned out to be 5-6 knots of bolt-on speed.  I may have to start manufacturing these and selling them.

So, with my Speedy Nose Dam, Speedy Tail, Speedy Engine Mount Fairings, and Speedy Cuffs installed, I did a max speed run at 1000' and I was surprised when the airplane went right to 193 KIAS and held it.  That was very satisfying considering the work done to make the changes.

I'm going to continue making aerodynamic cleanup changes.  200 KIAS is in my crosshairs.  But, even 193 KIAS at 1000' MSL for a normally aspirated, stock cowling, 3 blade prop, nose dragger is good.  Next I'll start on the main gear Speedy Dams, the hinge fairings, antenna fairings, gap seals, tail changes, and other clean up.  The benefits will be not only in top speed (my current goal) but in fuel savings at cruise speed.  I'm anxious to see if the fuel flow has dropped at cruise.

As my grandson, Chase, says, "To infinity ... and beyond!"

Engine Readings

24 Jan 11

Had a fun time flying the Spruce Creek Rally.  The goal is to fly three legs at a chosen ground speed and hit each of the turn points as close to the expected time as possible.  Any deviation from perfect is recorded as point against you.  Five seconds early is 5 points - 10 seconds late is 10 points.  And each leg has a predetermined leg time, so missing the first time by 30 seconds late and then flying supersonic to make up the difference doesn't work.  Anyway, I think my times were 8-0-3 for a total of 11 seconds - probably good enough for 4th or 5th place.  I flew the course at 120 knots and it was challenging to slow down that much.  The airplane burns 6.7 GPH at that speed.

I'm still slowly working on speed improvements.  Today I made the balsa form for the transponder antenna fairing.  I don't know yet if my idea to streamline the antenna will work, but we'll see.

The race is this coming Saturday so it will be interesting to see how the airplane does.

27 Jan 11

In the never-ending quest for speed, I'm making Speedy Fairings for the aileron hinges and the transponder antenna.  I'm making male molds out of balsa and finishing them with polyurethane so I can put mold release on them and lay glass on with reasonable assurance that I can get it off.

28 Jan 11

A short test hop today after I installed some air deflectors on the horizontal stabilizer tips.  Earlier, during high speed flight, the leading edge of the elevator horn was exposed to the relative wind by about 1/2" thus causing some, unknown amount of drag - or so I thought.  So I made balsa forms to fit on the tips to deflect air over the exposed horns.  Test flying with the balsa forms taped on revealed that the elevator horn dropped significantly with the deflectors in place which then left the deflectors higher than the elevators horns.  So, something was going on aerodynamically that caused more change than expected - or desired.  Plus, I could not fly as fast as I could without them.  Nelson theorized that perhaps there wasn't as much drag caused from the exposed horns as I thought.  He suggested that the relative wind was being push upward at a rate such that little of it struck the horn.  Flight testing indicates he is at least partially correct.  So, I made some thinner fiberglass deflectors for additional testing.  I'll wait until next week to test fly them since the race is tomorrow.

I also laid up the first fiberglass on the hinge fairing mold.  I sure wish I had vacuum bagging stuff because this would lend itself well to vacuum bagging.  If the prototype fairing turns out okay then I'll proceed with making all the other fairings.

29 Jan 11        Today - 1.0        Total - 134.7

Race day.  We had a beautiful, warm day with severe clear skies.  I was race 7 (although 2 pilots in front of me dropped out so I took off in fifth position) and we got airborne about 0830.  The Harmon Rocket in front of me didn't run away too bad.  I could still see him at the first turn point and heard his radio calls.  I was pacing fairly well with him considering he has 50 HP more.  The Baron behind me was never even close.

The RV ran well.  I was indicating 192 (194 KTAS) for most of the course, which after adjusting for the time to speed up after takeoff and time lost in the turns resulted in about 184 GS for the entire course.  So about a 4 knot gain over last year  I was very happy with how well the airplane performed.

Click here for Short Video of Race Start

Now back to the drawing board to squeeze another 8 knots out of it.

My initial try at making a hinge fairing is a bit disappointing.  But, it takes failures to make progress.  I got the fiberglass off the mold and did some initial trimming, but it's going to take lots of additional work to make it fit well.

Engine readings at high power, 1000' MSL, WOT, 188-195 KIAS

First numbers are from test flight yesterday.  The number 3 CHT kept creeping up.  I probably had it leaned a tad bit too much.

But today's numbers look good.  The #3 CHT stayed about 405 with the FF up a bit and the RPM down a bit.  The CHTs are all nicely matched except for #3.

Next update Feb