APRIL 2000

MEETING NOTICE The next meeting will be held on Sunday, April 16th, 2:30 at the Woodring Terminal

MARCH MEETING There were approximately 15 people present at our meeting. Dave Chaelís back from T-37 instructorís course in Texas. Heís with the National Guards now. Charlie Calivas talked about his RV 8 project. Heís looking for a constant speed prop for a 200 HP engine. For our May meeting, it will be held at Mica Doaneís, it is tentatively scheduled for May 21st. We found out at the meeting that we have lost Greg Lamb as our Young Eagleís Coordinator. If anyone is interested in taking it over, please let us know. Thanks for job well done, Greg! The Sooner Flight Academy will be held the week of July 10-14th. This is a good time to schedule Young Eagles Flights, so maybe we can arrange for flights then. It was mentioned at the meeting at possibly paying the $175 for a needy student to attend the Sooner Flight Academy. If any members are interested in donating to the cause, please contact Syd Nelson. Ray Gill told of upcoming Fly-Ins: May 6th in Guthrie for an Aviation Awareness Day. July 2 at Alva, We have $161.90 in our bank account.

2000 MEMBERSHIP DUES $10 You can mail your dues to Roy Camp, 2445 Sherwood Drive, Enid, OK 73703

EMAILING YOUR NEWSLETTER If any member is interested in having their Newsletter emailed to them, please let me know. Iím using Microsoft Word.

 

MEMBERS UPDATES

Gene Martin is in the process of moving his fuel pump under the seat on his Lancair.

Jerry Calvert has his RV6 fuselage in the jig .

Syd has revamped our airbox on our RV6. Itís similar to the old original airbox. We can now reach 2700 RPM and indicate a little over 200 MPH. It decreases the RPM on takeoff, but as soon as you push in the lever, it increases. Thereís no aircleaner thru the air inlet, on take off and landings, you pull your lever to get filtered, heated air. It has a screen on the front of the intake to keep the big pieces out.

AVWEB BRAINTEASER METAR, REVISTED The FAA recently released a new update of its "Aviation Weather Services" advisory circular (AC 00-45E). Below are questions from the revised AC.

Which of the following weather events would NOT meet the criteria for issuing a special weather report (SPECI)?

wind direction changes by 45 degrees or more in less than 15 minutes and the wind speed is 10 knots or more throughout the windshift.

RVR changes to above or below 2400 feet.

Thunderstorm begins or ends.

Volcanic eruption is first noted.

2. In a METAR or SPECI report, how is wind of 120 knots from 160 degrees denoted?

120160

12066

160120

66120

6620

What is the meaning of "RABO5E30" in a METAR or SPECI report?

Rain and mist obscuring the sky from 500 feet (estimated) to 3000 feet.

Reported braking on the runway indicates need for 5% to 30% (estimated) increase in landing distance.

Rabbits reported on runways 5 and 30.

It rained for 25 minutes during the period covered by the report.

4. What is the meaning of "SCT///" in a METAR or SPECI report?

There are scattered clouds at various levels up to 300 feet AGL.

There are scattered clouds at various levels up to 3000 feet MSL.

There are scattered clouds at various levels up to 3000 feet AGL.

There are scattered clouds below the elevation of the reporting station.

What is the meaning of "VIRGA NE" in a METAR or SPECI report?

A Virgin Atlantic pilot reported no (radar) echoes.

Precipitation is falling from a cloud but evaporating before reaching the ground, NE of the airport.

Visibility for Instrument-Rated General Aviation pilots is Not Established.

Lighter-than-air aircraft reported no (radar)echoes.

In a METAR or SPECI report, how is a temperature of three degrees below zero Celsius denoted?

Ė3

Ė03

(3)

(03)

M3

M03

 

 

 

What is the meaning of "LTGICCG" in a METAR or SPECI report?

Light icing reported by general aviation aircraft.

Low trough generating icing in clouds.

Lightning in-cloud and cloud-to-ground.

This is not standard METAR abbreviation and is probably a misprint.

 

What is the meaning of "MIFG" in a METAR or SPECI report?

Shallow fog.

Information regarding fog is missing.

Mixed fog and clear areas.

The entire state of Michigan is covered with fog.

What is the meaning of "SLPNO" in a METAR or SPECI report?

The cloud layer is sloping to the North.

Sea-level pressure not available.

Light snow in the Oklahoma panhandle.

Slight probability of Northerly obscuration.

What is the abbreviation for drizzle in a METAR of SPECI report?

L

DL

Z

D

DZ

ANSWERS: 1. E 2. C 3. D 4. D 5. B 6. F 7. C 8. A 9. B 10. E

OVER 200 MPH ON 160 HP Tech Counselor Input by Kevin Ross- EAA Chapter 983. Karla and I have been flying our RV6A for 5 years now and has 400 hours TT with an Aymar-Demuth prop. It does 183 mph TAS at 75% power, burning 8.25 gph. A friend of mine, Bill Steppling has completed his 6A. He has installed the steps, has no paint and very few instruments and flies 4 mph faster than mine! Heís using the newly engineered Sensenich metal prop and 160 hp engine.

With this in mind, I made a conscious effort to make whatever changes needed to go faster. I pulled out years worth of Rvators , read Kent Paserís book on speed modifying his Mustang Two. I got on the internet and sought out everything I could get my hands on ideas concerning drag reduction. Lots of opinions written and otherwise in application donít work. In short, I figured out I was on my own. Not too many people have made any modifications to gain speed. Many have re-engined to gain a few knots. I had considered buying a 180 horse, but with research it would only gain me 8 mph, a pretty good increase in the climb rate and cost me $13,000. I figured I could readily gain that much cruise through aerodynamic drag reduction.

Bill has been a good sport. From the start I clearly made a frontal assault and let him know straight-up that he will not have a faster airplane for the same horsepower than mine and that still stands. I wonder if I should have said that! We decided that all the technical/engineering B. S. aside that the proof was in the pudding. Being pilots and not engineers we decided that the best way to tell which plane was faster following any given change or modification was to fly the airplanes side by side, throttles wide open and see who moves ahead of the other. It quickly became apparent that the speed differential was so slight that we had to use our GPSís. Throughout our testing we typically saw only one or two mph increments difference between the planes.

The first thing I did was fair in the tail tiedown. I would have preferred to remove it altogether but it serves a dual purpose as a tiedown and a tail skid to prevent dragging the rudder on an over rotation on landing or takeoff (never have touched it though). After fairing it in I gained 3 mph in top speed. Bill used a slightly different design on his with the same results. We would make different mods to our planes and if it worked the other would do the same thing.

Bill plagarized off of Gary Greenís T-18 cowling and sharpened the awful frontal area between the main cowling and the intake scoop. At the same time he cut his draggy induction intake opening to a cylindrical 2 1/8". This mod was technically done by sticking a plastic Play-Doh can in the old intake and fiberglassing around it, removing it when it had dried. The intake looked awfully small and I didnít think it would be adequate air for the engine. This gained 4 mph. I stole a 2 1/16" shampoo bottle from my wife that was about 8" long and stuck it into my cowl inlet and fiberglassed around it. This gave me a longer cylindrical and slightly lower drag induction inlet than Billís. It got the inlet closer to the prop and I gained a solid 5 mph. It appears to us the factory cowl inlet scoops are very generic to accommodate a variety of engines and carburetors and thus much larger and draggier than need be.

The next mod took almost a weekís worth of part-time work and showed negligible increase in performance. The idea came from Ken Paserís book on aerodynamic speed mod and some factory twins. I extended the bottom of my cowling back and underneath my airplane by about 8 inches and made new exhaust stacks that point straight back instead of down into the airstream. The exhaust stacks donít extend beyond the cowl extension and donít show at all. The idea here is that the exiting cooling air should align with the relative wind passing along the bottom of the airplane instead of the typical cooling exhaust that causes the air to exit the cowling at a downward angle thus hitting /mixing with the relative wind and thus producing turbulence and drag. Furthermore, with the exhaust up inside the extension of the cowl it would facilitate and scavenge the cooling air out of the upper cowl. I and others believe(d) that the hot exhaust gasses exiting straight back instead of down and dragging would provide a minimal increase in thrust. Well, the proof is still in the pudding. It looks great. Is very aesthetically clean with great lines, no exhaust stack showing, but it didnít do anything from a speed standpoint that I could measure. It also really made a mess of the bottom of the airplane with exhaust streaks. So much so that the first time I flew it with it and with Bill closely flying chase (smart thing to do), we aborted the flight because he and I thought I may have been on fire or at least about to burn a hole through the bottom of my airplane. As a matter of fact, Ken Paser did burn a hole in his airplane doing a similar test. It makes one realize and think about how long it takes to get back to the ground from 3000 feet. This mod remains on my plane because it looks really cool and slick. I have changed the exhaust again to eliminate virtually all the stain on the belly. This mod did drop my CHT by at least 50 degrees and seems to have dropped my EGT as well.

The next mod was to change both planes to the larger and faster pressure recovery laminar flow wheel pants. This is a $180 option that Vanís came out with several years ago and all but guaranteed 5 mph plus in speed. It worked as advertised.

We both have made smaller changes always trying to measure minute and many times imperceptible changes. Some of them include fairings for the trim tab on the elevator, fuel drain cock, rudder cable/horn, pitot tube, new nose gear leg and empennage gap seals to name a few.

Well you say, what is the bottom line? What have we gained? Well, Iím not exactly sure because "the fat lady ainít sung!" to date we have each gained around 15 mph during full power runs at 2500í MSL and 8000í MSL. We can both consistently attain TASís in excess of 200 mph which we couldnít do before. Typically, we true out now around 203 and 205 mph. While pleased with the speed increases, we know there is a bit more to be had and weíre going after it.

What we have gained the most is knowledge through experimentation. I must comment on the fact that the FAA through the "Experimental" Special Airworthiness Certificate has given us a tremendous amount of latitude to literally experiment with our airplanes. We can legally make these changes and modifications without their intervention assuming they donít meet the definition of a "major modification" and in the very near future will be able to do the same with major mods. We couldnít do this with a factory built, certificated plane nor would we see anything near this performance per horsepower and fuel burn.

Another note is that anytime you make a change to your plane and fly it you are a test pilot, period! This is not to be taken lightly. Consideration must be given to flutter, red lines and "what ifs."

What lies ahead? We ainít done yet! No doubt more experimentation. At this point I canít look at that airplane without thinking about the "what if" or " I wonder about that". Anything hanging out in the breeze is a target. My transponder antenna is going to be moved off the bottom of the plane and out of the airflow, but I havenít figured out where to put it yet. I may try to hide my comm antenna in my nose gear leg fairing. Bill may test fly his without wingtips. (Editorís note, Syd and I have tried this on our RV6, it makes the plane roll faster, but it increases stall speed and decreases top speed). Iím working with Ron Shuster on forming a clear vertical stabilizer fairing so that I donít have a "bump" on the top for anti-collision light. We know that it was fairly easy to get 200 mph but as speed increases the drag increase is exponential and future gains will be hard fought. Only the greatest attention to details will make a difference.

One last thing, the last time we ran our GPS speeds were the same. Iíve got to do something about that. Iíve got many ideas remaining but I donít think Iíll share them with Bill quite yet, CUZ THE FAT LADY STILL AINíT SUNG (and probably wonít for awhile)!!!!