On Friday, December 11, 2020, I issued an Airworthiness Certificate to Mr. Gregory Rodriguez for his Amateur-Built AL18. This was, in fact, my 1,000th aircraft certification as a DAR since receiving my designation in September of 1999.
by Michael Stephan
A small gathering of curious onlookers watched the event, just a few of the Grand Prairie builders including his son Ben.
Since the RV-10 had a new Lycoming engine under the cowl, Charlie needed to make a longer flight to help with the beak-in of the O-540. To do that he stayed in the airspace just above the airport and out of the Class-B and orbited for about an hour, coordinated ahead
of time with the GPM tower. It didn’t hurt that the Airport Manager is also a friend.
Since that first flight Charlie has made a few more flights. He is employing the Additional Pilot Program and is nearly finished with the Initial Tests Package (ITP). Once finish with that he will add an additional pilot on further test flights. His two sons Ben and Chris are both experienced pilots and I’m sure are very interested in being that additional pilot.
Charlie did such an excellent job on the build that there very few squawks. After the first flight the examination under the cowl reveal a leak free engine install. The only issue was a slight discoloration on the inside of the cowling from the heat off the exhaust. On a recent flight, I monitored the speed on one of the flight tracking apps and saw a ground speed of 203 mph, which doesn’t seem that remarkable except it was done without gear leg fairings and wheel pants. So, the RV-10 is going to be much faster that the RV-9A he built previous to this RV.
The next step is to continue the Phase I flight testing, using the steps in the Additional Pilot Program and the EAA Flight Test Manual.
N56VA is a full IFR equiped airplane with a Garmin G3X panel. So, there is plenty of discovery and tweaking that will happen during testing.
First Flights are rare and we are excited about our first one of 2021. One, I hope, of several that we have this year. As any builder will attest, completing an aircraft is an exercise in small victories and patience, and this is a second completion of Charlie’s.
Congratulations Charlie on an excellent build!!
By Sam Cooper
For those of you who were able to attend the March 2, 2021 Chapter Meeting presentation on Aircraft Engine Management, I hope that you found the material interesting and informative. One of the things I have found frustrating is that very little hard data was presented on four cylinder aircraft engines, let alone a carbureted aircraft engine. So, instead of unkind adjectives I will show you some data on a typical Experimental/Amateur Built (E/AB) aircraft engine.
In the middle of April I was generously invited by fellow member Norm Biron to ride along in his Glastar while we tested the air/fuel (A/F) mixture distribution on his Superior XP-O-360 with an updraft carburetor and a constant speed propeller. After departing KDTO, we headed north, cleared the Class B airspace and climbed up to 8,000 feet. Once we were level and stable, Norm set the engine RPM, went full throttle and full rich on the mixture. Norm’s Dynon FlightDEK-D180 did the hard work of logging the flight and engine data. Once the temperatures were stable, Norm started the mixture sweep by reducing the fuel flow by about one gallon per hour. We let everything stabilize, and then reduced the fuel flow again. We used eleven different fuel flow settings until the engine vibration at low fuel flow (i.e. lean A/F ratios) led us to stop the mixture sweep. The vibration was not horrible, but not where one would choose to run the engine. Returning to a richer mixture, we descended and landed back at KDTO.
Norm sent me the Dynon log and I spent some time extracting and analyzing the mixture sweep data. Norm has graciously allowed me to share the following data with the rest of the Chapter.
Figure 1 shows the primary result of our mixture sweep test, the variation of Exhaust Gas Temperature (EGT) and Cylinder Head Temperature (CHT) with fuel flow for Norm’s Superior XP-O-360 carbureted engine. The response of the EGTs and CHTs matched the response I was expecting and I was happy to see that we were able to get all of the EGTs to peak before we stopped the test. All of the CHTs generally peaked about 40 °F Rich of Peak (ROP) before its cylinder hit Peak EGT. There are text boxes in Figure 1 noting when the Peak EGTs and the Peak CHTs were reached. The two rear cylinders (4 and 3) peaked in sequence, then both front cylinders peaked roughly together. The total fuel flow spread between the first and last cylinder to peak was 1.2 gallons per hour (gal/hr).
For the CHTs, all of the cylinders peaked within a 10 °F temperature range. And with a maximum CHT of 385 °F on Cylinder 4, we had left a nice margin to the cylinder temperature limits. The flight conditions are noted in Figure 1. At 8,000 feet indicated we ran at a roughly 66% power ROP setting. The outside air temperature (OAT) at altitude (34-37 °F) was 4-7 °F above Standard Day temperatures.
I have seen curves for how an engine’s horsepower output will vary with fuel mixture. Some were conceptual, and some had hard numbers, but only a single curve for the engine’s total output. That is what is more important to a pilot. However, a lot more detailed data is measured for serious engine development, but not necessarily shared. Like most E/AB aircraft, Norm’s Glastar does not measure the engine’s horsepower output. Norm’s Dynon EFIS and EIS estimate engine power percentage, which is very useful to Norm when he flies the Glastar.
I was curious to see if there might be a way to estimate the effect of the A/F mixture distribution on each cylinder’s horsepower output and the cumulative effect on the engine’s total output. I had access to Superior IO-360-B1A2 (injected version of Norm’s engine configuration) EGT and Horsepower fuel mixture curves for a 23/2300 (about 69% power ROP) condition. Using that data, I was able to estimate the individual cylinder power percentage and the total engine power percentage relative to the peak EGT power of the XP-O-360 during the mixture sweep. Those first order power estimates are shown in Figure 2 along with the EGT measurements versus the fuel flow.
If you look at the Engine Estimated Power line (purple dashed line) in Figure 2 you are probably wondering how can that be above 100%? The only engine performance landmark we directly measured with Norm’s EIS is Peak EGT for each cylinder. That Peak EGT fuel flow establishes where that cylinder had a stoichiometric (i.e. chemically balanced) A/F ratio. From this I estimated individual cylinder A/F ratios and fuel flow percentages relative to cylinder Peak EGT. Then, cylinder power was estimated relative to cylinder Peak EGT. Superior’s mixture curves show Peak HP at 50–80 °F ROP at 4-5% more horsepower than at Peak EGT. My estimated engine power reached a maximum just below 104% of the Peak EGT horsepower level at 9.2 gal/hr fuel flow, which was 10 °F ROP for cylinder four, which peaked first. The variation of the horsepower percentage is what is important here, not its absolute value. The horsepower percentage peaks above 100% because the reference is Peak EGT, which is not where maximum horsepower is produced.
The A/F mixture distribution causes the timing of power loss relative to fuel flow on individual cylinders to be different from each other. This can be seen in the lower left corner of Figure 2. The result is different power levels (vertical spread between the cylinder estimated power curves) from the individual cylinders once the mixture is lean enough. The power pulse differences every 180° of crankshaft rotation cause vibrations that the pilot usually choses to avoid if they are great enough. The A/F mixture distribution also flattened out and spread the engine’s cylinder horsepower peaks around so that Peak engine HP is very close, 10 °F ROP for cylinder four, to the first cylinder to hit Peak EGT. The net effect is to slightly reduce the maximum engine horsepower that is available, to broaden and flatten the top of the horsepower peak, while moving that peak horsepower closer to where the first cylinder will hit Peak EGT.
After 800+ hours of flying the Glastar, where does Norm fly it when he wants to cruise efficiently? He sets the power level, manifold pressure and RPM, to reasonable values and then leans till cylinder 4 just goes past Peak EGT and cylinder 4 is just Lean of Peak. The engine vibration is fine at that condition, leaner fuel flows just make more vibration and quickly result in lower airspeed. To me, it looks like this data set and analysis supports what Norm has learned through many years of flying his Glastar.
Learning from the Process
The newsletter version of this article focused on the air/fuel mixture distribution results from the mixture sweep flight test. This expanded version covers additional topics that may be of interest to the readers.
For the mixture sweep flight the Dynon FlightDEK-D180 was configured to log data at ten second intervals, which is Norm’s usual setting that allows him to log several flights before his older data is overwritten. The FlightDEK-D180 can log as frequently as once a second, but older data is then overwritten in 30 minutes of operation. The longer logging interval for our flight was not ideal, but did not substantially affect the results.
Figure 3 shows the as logged EGT and Fuel Flow values. The start of the mixture sweep test itself was about 16:16, when the mixture was set to full rich from a much leaner condition. We ended the test at 17:13. The fuel flow trace is the least smooth. The EGT traces all had similar smoothness, but I will note that they were logged in 1 °F intervals. I prefer the 1 °F resolution of the data and can smooth out the “noise” as will be shown shortly. Yes, EGT1 sure appears to be reading low, which it has done for the last few months. Norm has already replaced his EGT probes at least once, the probes are consumables. But, EGT1 had the same time history profile as the other sensors, just with a smaller vertical scaling factor.
Figure 4 shows the smoothed EGT and Fuel Flow values that I used to select the extracted data values. For post test data smoothing I like to use a centered, moving average. A centered, three point moving average for a row is just the average of the row’s reading, the previous row’s reading, and the next row’s reading. A centered, five point moving average is just the average of the row’s reading, the previous two readings, and the next two readings. (This would not be possible if live data is smoothed since the “future” readings have not been made yet.) The gray vertical dashed lines in Figure 4 show the location of the time stamped data rows that I selected to extract the mixture sweep data points from. For example, the first row extracted was at 16:19:10, the fuel flow was 14.1 gal/hr and EGT1 to EGT4 were 968, 1035, 1101, 1137 respectively.
I tried to extract the data points from locations were the fuel flow had been steady for a while so that the temperatures would be closer to a steady state condition. So, most of the gray vertical dashed lines are at the right end of a plateau in the fuel flow data. Due to our inexperience with this type of testing, we were a little quick to adjust our fuel flow setting, especially at the beginning of the mixture sweep. This compromised some of the first four sets of readings, but we were more patient after that. We also transitioned nearly straight through the EGT4 peak temperature, which occurred at 16:43:00. I used that data point since it was the best we had for Peak EGT4 temperature.
Figure 5 shows the smoothed CHT and Fuel Flow values that were used to select the extracted data values. I did not have to apply any smoothing to CHT2 and CHT4, these are the as logged values. In contrast, the as logged CHT1 and CHT3 values had more “noise”, the cause of which is not know at this time. So, I applied a centered three point moving average to CHT1 and CHT3 for the traces shown in Figure 5. The gray vertical dashed lines in Figure 5 show the location of the time stamped data rows, the same rows as in Figure 4, that were used to extract the CHT temperatures from.
During the Chapter Meeting presentation on Aircraft Engine Management, Technical Counselor Mel Asberry made the comment that CHT readings are very slow to respond to changes in conditions. Prior to this test flight, I did not know exactly how slow that response can be. It is very obvious in Figure 5, if you look at the slow response of CHT4 before the last three extracted data values. If one of the goals of the mixture sweep is to have stabilized CHT values, there will need to be significant dwell time at each individual fuel flow settings.
If the end portion of the mixture sweep time history in Figures 4 and 5 from about 17:00 onwards is inspected, some of the responses look out of line with previous responses to fuel flow reductions. This was when the engine vibration was at its worst. Three of the EGTs show a dip and then a rise even though the fuel flow was still decreasing. EGT4 became a lot noisier, even with the smoothing. CHT4 had more “normal” appearing drops to plateaus. But, CHT1, CHT2 and CHT3 got hotter in loose synchronization with their EGTs. I do not know the cause of this. Given the engine vibration at those fuel flows, most pilots will not choose to operate this way.
We have a new airplane completion in the Chapter as Tom White flew his RV-8 on Aug 18th. For years we have only had a handful of few first flights, and in the last three months we have had three. Don Christiansen, Greg Schroeder, and now Tom White. Tom’s RV-8 is the lightest RV I have weighed in all the years I have been weighing airplanes. When Mel inspected the plane I asked him if any parts were missing, because I don’t know how Tom did it. I was impressed with his RV-8 build.
Light airplanes fly the best and Tom’s should be a real nice flyer. Congratulations Tom!
In conjunction with the rash of first flights, we have implemented our plan to celebrate them. So, we exited our COVID caves, gathered together at Northwest Regional Airport (home of Greg and Tom) and safely distanced and celebrated these huge milestones.
Tom rolled out the grill to cook a few hotdogs, and Norm brought a cake to celebrate the first flights. Several other members flew in to help get into the spirit of flight. Norm brought his Glastar. Brad Roberts flew his RV-6 and Joe Migas and A.D. Donald flew their Cessnas in.
Also taking part was Don Christiansen who brought over his recently completed Rans S-21. So we all got a good look at that new airplane as well. We spent several hours looking at new planes, eating hotdogs and cake, and enjoying the rare opportunity of each other’s company in this very strange year. We had a great turnout for our first celebration.
I want to thank Ann Asberry and Norm Biron for arranging our lunch. I especially want to thank Tom and Greg for hosting the gathering. I also want to thank all those who made it out to Northwest Regional which made the day very special.
By Michael Stephan
Since the pandemic has shut down our in-person Chapter meetings, I flew out to Stephenville on an early August morning and met Don Christiansen to award him our Chapter’s First Flight Plaque. With me and holding the camera was Norm Biron. He also brought the plaque.
This is a very special picture, since first flights are rare occurrences. We have only had a few of them the past 5 years. So being able to congratulate a builder for a first flight on behalf of the Chapter is very special.
Don, Norm and myself celebrated by having breakfast at restaurant just down the road from the airport. We don’t get to see Don that often, so it was enjoyable to spend time catching up and listening to some of the stories of him flying the Rans S-21 in the Idaho BackCountry.
One of the revelations that I learned about the Don’s S-21 is the Whirlwind ground-adjustable prop. Don said it was pitched to optimize cruise speed, but when he arrived in Idaho and planned to fly in the high density mountain air, he was able to adjust the pitch to generate more RPM and hence more horsepower.
Having hopped around Idaho for the summer, Don said the airplane will be in the paint shop next month.
It is with great excitement to announce that another Chapter member has completed a First Flight.
On August 20th at Northwest Regional Airport N800GY took to the skies for the first time. On his builder’s log Greg said this about that day:
“Today is the long awaited day. First Flight! Thank you Norm, my ground crew. It has been a heck of a journey … I have turned from builder to maintainer & operator.”
By Greg Schroeder
I ordered the Sportsman 2+2 tail kit from Glasair back in Nov of 2005. I started building and checking things off the list, then moved to Florida in 2011, then to Dallas in 2014 and saved the kit from a divorce. I have finished the roller coaster ride of building and completed first flight the morning of August 20th from 52F. There has been a lot of help from the Glasair Owners forum both online and in person. The factory sent irregular shipments of parts to replace the ones I screwed up from time to time and Dan Dudley provided me transition training to make sure I could fly the Sportsman. A few months ago I stuck my nose in an open hangar and met Tom White who became my building brother. We went through the last few months to first flight in lockstep. Jim Novak and Joe Migis fellow builders and chapter members who helped and cheered me on. Michael Stephan provided scales and support with weight and balance. It was then time to ask the DAR, Mel Asberry, if it was airworthy.
Mel worked me through the FAA paperwork and got me to airworthiness. The crew chief Norm Biron provided a second and third set of eyes on any squawks while I worked to get us to zero. Norm is a great mentor and ground crew member helping get the plane into the air and continues to be a sounding board for my steps through Phase I. In summary, I found out it does take a whole team of people to get an airplane completed.
I’ve had many rides in GlaStars and Sportsman owners/ builders. I want to thank all those who have patiently answered questions both simple and complex. I am looking forward to completing Phase I and return the favor of those rides. I will see you all at a Fly in, and join the formation into KOSH.
N800GY is no longer a project but a plane. I look back and simply can’t believe what it took to get to this point. Persistence, maybe stubbornness, are the only words that come close to encapsulating the experience. To other builders, stick to it. Keep making progress. The tasks do come to an end, and all that is left to do is fly it.
N800GY flew like a dream. I do have the heavy left wing and have to work on cooling. All issues others have seen with lots of potential solutions. I’m working on the Garmin VIRB cockpit video. I’m working through Phase I using the EAA Flight Test Manual task list moving toward Phase II.
by Michael Stephan
The McKinney Chapter arranged a tour of the Legend Cub Factory in Sulphur Springs on March 16th, and we were lucky enough to be able to tag along. We had a large number of members attend.
The popularity of tube and fabric aircraft is on the rise as an explosion of bush-flying videos are posted on the internet. So it was no surprise to see so many interested in seeing the Legend Cub Factory. I’m one of those interested.
The Legend Cub is not a typical cub. These Cubs are bigger, safer, and fabricated to exacting standards with the combination of high tech materials and methods along with some old school craftsmanship.
All the parts are fabricated in precision jigs that are checked for accuracy several times a year.
Lightness plays a big part and Legend is using newer materials to aid in that matter. Composite honeycomb-core floors are practically weightless. The floats are also made of a carbon and kevlar honeycomb composite. They are so light two people can lift them easily. There is also more lightweight composite material used in the fabrication of the cowls.
We are starting to see more technology in the landing gear as performance takes precedence over originality. More shock struts and less bungees is what you will find, and some of the struts are highly engineered.
The factory also does a fair amount of refurbishing and repair for customers. New Cubs shared the floor space with others getting repaired as well as a few upgrades. Legend also does high end restorations as well.
One of those restorations currently underway is the first customer delivered Bonanza. Serial number 4 was being completely restored on factory floor. Look for it to be on display at Oshkosh this year.
Founder Darin Hart , hosted the tour of the welding shop and the fabric covering area. He gave a compelling history of the company as well as what makes a Legend Cub a high quality and unique airplane.
If you have enough money, Legend can build just about any Cub you want. Other Cub manufacturers get a lot of buzz and cost more than planes twice their size, but Legend has a
product that gives you more for a much lower cost. There is a bunch of Legend owners that would agree with that.
I would love to have one.
I moved my RV-7 from my garage to the airport on February 21, 2019.
Dave Buono is renting me the back corner of his hangar at Aerocountry.. I don’t know what to do with this much room after being in the garage. My RV is a hangar-mate to Bruce
I called a few towing outfits in McKinney. Some didn’t even want to talk to me. I think they thought I was moving a 737 or something. I found a company called Expert Towing. They were
eager to help. One of their drivers came to the house a couple of days before I wanted to move just to make sure he understood my needs, the size of the airplane, etc. We arranged a date and a price.
The morning was rainy with some thunder, but by the time the truck showed up, things calmed down. The airplane had never been wet before, though… Chris and Alonzo from Expert Towing were very professional and catered to my wishes and my knowledge of the airplane.
I lost the truck in my own neighborhood, so I just headed to the airport on my own and waited for them. They weren’t far behind, though. Unloading went very smoothly. The next week, I rented a 16′ truck to move my wings, various parts, and toolboxes. We filled that truck and made sure every item was firmly tied down.Now we’re in our new home, and I’ve even already started doing a little bit of work on the airplane.
By Michael Stephan
Last month I paid a visit to Brad Robert’s OneX project. After a bit of time off from it, I was glad to see all the recent progress. That airplane is
nearly complete. He has all the firewall forward finished. The instrumentation is in and functional. He is using the MGL Avionics instrumentation as is common in many Sonex builds, due to the compactness of the unit and the limit space available in the panel. We did a few functional checks on the control system and everything is looking good. The only construction left was on the outboard wing panels which includes the unique folding mechanism.
Like he did with his RV-7, Brad plans to paint the OneX before the first flight. On the bright side, there is a lot less airplane to paint with the Onex. He used the Stewart system on the RV and he plans to use that paint again. It is a water-borne paint and is much safer to use and he got good results with it on the RV.
The OneX is an interesting plane. The kit from Sonex is very refined and simple construction that incorporates blind rivets. It is no slouch in the air either. The 80 hp Aerovee engine provides ample power to pull the plane at a brisk 155 mph, and even though the wings fold the OneX is aerobatic.
At the May Chapter meeting, we had a special presentation of the Wright Brothers Master Pilot Award for 50 years of Aviation professionalism, skill, and expertise for Mel Asberry. Presenting the award is Tony Baumgard of the North Texas Flight Standards District Office.
This is a major achievement for any pilot. The FAA is focusing on improving safety and rewarding those that practice that over a long flying career is a great way of doing that.
Mel is a great example of diligence and professionalism. He exemplifies what the award is. All the knowledge and experience Mel has accumulated, he generously shares with the aviation and homebuilt airplane community. We are proud to have him as a Chapter 168 member.