2014 Past News and Events
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The photo above shows the crank trigger wheel installation. Look closely and you'll see that the outer circumference of the wheel has begun to eat away at the pickup sensor, and if you look very closely, you'll see where the wheel has failed at the bolt slot near the center axis.
I attempted to fly Doll on Christmas Eve afternoon, but on climbout the engine began to get "bumpy." I checked gauges and leveled off at 6,500 feet, verifying gauges and setting up for level flight. I then turned off the MSD distributer ignition side and the engine went bad, verifying that the crank trigger ignition side had gone bad. I returned to MGM and landed, then drove my trip instead of flying.
That weekend, back in MGM, I removed the cowling and found that the crank trigger wheel had failed at the three bolt locations that attach it to the harmonic damper, thus allowing the damage to the sensor and the rough running. After a bit of research and listening to learned opinions, we are planning to change the cam to a smoother low end equation, replace the fluid damper with an elastomeric damper, reconfigure the pulley system more toward conventional automotive pulleys and belts to shorten the shaft extension that carries three cog belt pulleys, and fly on.
Of intense concern to us is, as others have faced, the physics of torsional vibrations and resonance. We can't fully determine whether or not this wheel failure is a problem with the wheel, or an induced failure of a good wheel due to vibration characteristics beyond the norm. The new wheel will be a solid disc without the lightening cutouts, which should help. The pulley wheel we'll use will provide better clamping and spread the pressure of the three mounting bolts better. The cam change will give us a smoother idle than what we have been experiencing. These and a few other refinements will, hopefully, keep this engine running smoother, albeit with less top end power. As I said to Mr. Stewart, if we can tame this engine down and have less power, we'll climb out more like a real Mustang instead of like the Jupiter missile we climb like now.
We'll keep you posted.
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The photo above shows the new crank trigger wheel, the original pulley mandrel, and a 1/4 inch thick steel retaining ring we had fabricated to better spread the load of the three retaining bolts. The damper is the same fluid damper we had removed. Our new elastomeric damper wasn't drilled for the pulley mandrel we are using, so we reinstalled the original. The point of this setup is to get the engine back together enough to ferry her down to Bartow, where we will go further with the changes we discussed last month.
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Above you see the pulleys and belts reinstalled and ready for runup.
Below, Doll sits after a successful runup and leak check on Sunday February 2nd. Within a few more weeks, we'll get her recowled and ferried to Bartow, where we'll probably pull the engine, install a new hydraulic cam and lifters, drop the pan to make a visual of the crankshaft section, install the new damper, and possibly re-engineer the pulley setup.
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Saturday, February 15th: The flight from Montgomery down to Bartow was perfect: Engine ran fine, tailwind, clear blue sky, as good as it gets. Waiting in Bartow was a great group (hate we didn't get a photo) including Jack Peck (S51 Merry Mary), Dan McGarry (S51 Top Duck, the first kit to fly), Kevin Armstrong (S51 in England almost past the inspections and paperwork required by the CAA in Great Britain), Frank Zersky (recently bought partially completed kit and is beginning his work), and Harry Stenger and Neil Butterworth of Aero Fabrication. We'd have insisted Jim Stewart be there, but it was an impromptu gathering that just sort of happened, and we didn't have time to get Jim and Peggy on board.
Even with the engine performing so well, we still went ahead with our plan to pull it for the mods we discussed earlier. Spent Sunday disconnecting and draining, and had the engine out of the frame by noon Monday. Harry will now remove the cam for regrind to a "milder" hydraulic set-up. We would like to have this work done and flight-proven by Sun n Fun, but it probably won't happen, given the way these kind of jobs go, and the delays that creep in. We want to get this engine smoothed out at idle and log more time on it as part of the longer range program, and missing Sun n Fun again might be one of the prices we pay. We'll see.
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Above, the 588 in the sling coming out.
Below, on the stand for further disassembly.
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Harry and Hank will be moving the project along for the next two weeks. I'll try to get back down weekend after next and "help." Like Hank said, "You can help and we'll have it pulled by Supper, or I can do it alone and have it out by Lunch."
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You are looking above at the base flange and the oil spray tube for the PSRU.
As we were disassembling the PSRU, we found the broken tube and began to theorize as to why it had let go. There is, of course, vibration in the box and the engine. We will also be checking alignment to see if there was any side pressure at the O ring end that might have contributed to the failure.
In having new tubes manufactured, we had already decided to fabricate with a constant diameter rather than incorporate the turned down sections that this tube has. It's simpler to build. This will allow us to have more material in the tube, which might allow us to overpower this symptom even if we can't eliminate it. No one else has had this failure that we are aware of.
The other conclusion we have reached is that we will not put any more effort into evaluating this particular 588 engine. We will, instead, back up and build a 502 based engine. Jim's prototype flew about 400 hours with a 502, Jack Peck is approaching 300 hours in his 502, and Hartzell has already approved the PSRU with a 502. The 502 generates plenty of power and is a proven concept. We can build wi th a shorter crankshaft throw, hydraulic lifters, shorter rods and different pistons for a lower compression ratio; an elastomeric damper, fully electronic fuel injection, and a wet sump. Al assures us that this 588, with the milder hydraulic cam and lifters, new damper, and tuned fuel injection can run "like a pussycat." Other engines might work, but we are going back to the tried and true 502.
We will be getting the 588 from Bartow to South Carolina, along with some other engine cases, cranks, and parts from Montgomery, to see what we can use from what we already have. We'll be down longer than we wished, but believe that taking two steps back will get us further along in a good direction than continuing to develop the 588.
Below, you'll see the area on the bottom of the tube that was rubbed by the gear. Jim had designed the units to be lubricated by the jets in the tube as the gears come out of mesh. The tube stayed in pretty close relation to its intended position, being held by the O ring end of the tube in the boss receptacle in the center case. Had the tube come out, it looks to us like the tube would have been kicked to the wall of the case and settled in the case sump, rather than, if it had been on the into-mesh side, been pulled through as scrap steel through a shredder. Out-of-mesh is the way to go.
We'll keep you posted.
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During late March, early April, Harry shipped the 588 engine to Al Joniec and Robert Abernathy for evaluation and recommendations for our next steps. We also delivered two other blocks, two cranks, cams, lifters, and other engine parts we had bought and stored for the kit and the prototype as choices from which to pick components for the next build. Mike Goranski met with us in South Carolina to go over these items and think through changes he might make in his engine setup. We had a very, very interesting and educational session with Al and Robert that Friday.
After evaluating and discussing, we have decided to build a 540 cubic inch engine for Doll, and a 500 cubic inch engine for the kit. The 540 will use the dual plug heads, distributor and crank trigger ignition systems, hydraulic lifters, wet sump, and the AirFlow fuel injection unit. The 500 will differ primarily by having a state of the art fully electronic fuel injection system with single plug heads.
For now, we have sent the Airflow unit to Rivera for a full overhaul and calibration, and are selecting parts for the 540 buildup. We'll report as these engines come together.
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Above is a photo I took last weekend of the firewall with the external oil tank and other systems in place as required for the previous dry sump lubrication system, and below is a photo after removal of the tank. The oil will be carried in the new engine in the pan, hence the term "wet sump." There are tradeoffs in using one system vs. another, but we think that the success Jack Peck has had, and the relatively low RPM (4750 Takeoff) we are using says that a wet sump system is fine. Continental and Lycoming are wet sump, most cars are wet sump, and going wet sump eliminates much of the external oil lines we were having to use. A dry sump system does offer some advantages, but none we think we have to have.
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Wet sump firewall without external oil tank.
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Harry's hangar cat helped through the morning but was just plumb tuckered out by afternoon.
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Great news from Kevin Armstrong in England: After six long years of working with the Civil Aviation Authority in the U.K., his Stewart S-51 flew again!
I say flew again because this airplane originally flew in the U.S. under ownership of the late Sheridan Owens. Kevin bought the airplane and had it ferried to California, disassembled for shipping, floated to the U.K., reassembled, and has undergone inspections and proving and documentation and engineering data for the CAA, and, today, watched as his U.K. appointed and approved pilot took her up for two short flights.
The first flight was a ten minute ops check, while the second was a thirty minute flight envelope procedure. Got her up to 230 knots at approximately 3,000 feet at 4,000 RPM.
Congratulations to Kevin and thanks for the time and effort he put into working through the CAA requirements to get her airborne in England. He'll have his pilot go for five total hours, then Kevin will take the controls and have a go.
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Most of June was spent collecting components for the new engine build. Our new reverse rotation / reverse polished crankshaft arrived in South Carolina mid June, but travel schedules and other summer activities have delayed final assembly.
Our engine guru, Al Joniec, is seen below on his recent trip out west advising and consulting with a west coast car collector. Al got him straightened out on a few things and is now ready to finish up our engine. Our engine should begin going back together the second week in July. We'll be checking proper indexing of the existing PSRU rear case and the newly manufactured rear cases on this new engine.
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Above is a shot of the original design spray bar for the PSRU, with the new design on the right. Jim Stewart approved the new design, going with a constant diameter tube rather than the turned-down design. These new spray bars have been built by Bill Locher, who has been immensely helpful in thinking through the new design, checking and double checking dimensions and design. You'll notice that the new spray bar is also longer than the original, and has provision for two "O" rings at the aft end. This allows the bar to seat more deeply in the socket in the center case for a more secure assembly. We'll be installing this new design in Doll's PSRU.
We will be at OSH this year, but will not have Doll ready to fly her up. We'll be with the Replica Fighters guys or at the Visit Pensacola booth in the exhibition hall, right next to the Sun n Fun booth. Please stop by and see us.
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Al Joniec, left, and Robert Abernathy, right, display the block for the 540 cubic inch engine they are about to assemble. We reviewed the other components and enjoyed more education from the two of them as to some of the nuances and improvements we would incorporate in this build. No real rocket science: Just Al's and Robert's experience and awareness of issues and techniques for what we are trying to accomplish, much of which will be easier to achieve in a shorter throw, milder cammed 540.
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Two shots above of Bill Keyes' Turbine S-51 at the Replica Fighters area. Bill has it in beautiful shape and was our lone S-51 at OSH this year. He has the new landing gear installed and has been flying aerobatics, giving those of us at our builders group dinner his version of entry speeds and handling characteristics. Bill is former Air Force in some pretty nice high performance fighters, and now flies with UPS. We had a nice dinner that included Jamon Pruitt, Frank Kersey, Charlie Hudgens, our Spritual Leader and Counselor Owen Smith, and me.
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And, speaking of Owen Smith, here he is getting ready to depart OSH in his Bearhawk. Bearhawk or not, Owen is still an S-51 guy, assisting and helping our group with his experience and expertise, and we do appreciate it. I really enjoyed the time I got to spend with him this year.
Other guys called in: Spoke with Czach, Dan McGarry, Eliot Cross, Harry Stenger, and Cliff Fitch during the week. Everyone appreciated Bill Keyes getting his airplane up there to represent the breed.
There will be more news this August. Stay tuned.
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Assembling the Prop Speed Reduction Unit.
During the last week of August, we reassembled Doll's PSRU. Here, we have the center case cleaned up and ready to install components.
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Harry has lined up the front prop shaft seal and placed tools to drive the seal into the front prop bearing cover.
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Above, Harry drives the seal into place using the hydraulic press and properly sized tool.
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The front prop shaft bearing has been installed. This bearing was cooled in the freezer for several hours and the case and liner were carefully heated with an oxy-acetalyne torch. The bearing took a little coaxing initially, then slipped in nicely.
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The prop shaft spent the night in the freezer. Here, we have slid it down into place through the front bearing, ready to press for its final fit.
Below, the shaft on the way in.
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Above, prop shaft installed.
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Rear view of prop shaft installed through front bearing. The splined area is where the driven gear will be located.
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Above, steel spacer in position on shaft.
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Driven gear down on splines, rear prop shaft bearing in position on prop shaft.
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Slotted washer in position on shaft.
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Tabbed washer in position over slotted washer.
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Prop control oil tube ready to screw in.
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About to crank down on oil tube.
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Tab washer bent into locking position at bottom of picture.
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Pinion shaft and bearings installed in front case, flange cleaned and coated for mating to center case.
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Front and center cases mated.
Next step is to take this assembly to South Carolina, where the 540 cubic inch engine has been built up. We plan to run the engine on the dyno, then mount the PSRU with the rear case, install it on the engine, and run the entire system again.
Below, you see the new engine being run on the dyno in South Carolina. Robert and Al had already run it in several days before I got up there, and had retorqued the heads and made final adjustments.
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This photo was taken as the new 540 cubic inch engine was being warmed up on the dynamometer the last week in September. Notice the difference between earlier photographs on the Past News and Events updates of the prior 588 cubic inch dry sump engine and this wet sump engine. Al and Robert have been able to simplify the pulley and belt arrangement greatly. There will ultimately be more hoses than what you see here, but, again, we will have fewer hoses and lines in the final installation of this engine than what we had on the 588 installation.
The engine ran out pretty well, coming in with more power and torque than I was expecting. The idle wasn't as low and smooth as I was looking for, but Al did some more fine tuning the following week and worked it down to run slower and smoother. Once we get the engine down to Bartow and fully installed with PSRU and prop, we might have to idle it back up again anyway.
We anticipate shipping this engine the week of October 13th. I'm assuming we'll be a couple of more months as we re-engineer changes to the aircraft systems to finalize the change from dry sump to wet. I guess having to spend time in central Florida in December won't be so bad.
Meanwhile, GREAT NEWS from Kevin Armstrong in England: The British CAA has officially approved his aeroplane and will be presenting his Certificate of Airworthiness this week (this update written on October 6th). Kevin himself will soon get to fly his Stewart S-51. We all admire Kevin for his persistence in working through the CAA process. Good luck, Kevin, on your first flight and all others to come.
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More about the new 540:
Robert personally delivered our new engine in late October. The darn thing produced beautiful torque and horsepower results on the dyno runs, showing 606 to 626 hp and 677 to 700 ft-lbs of torque at 4700 RPM, with 405 to 426 hp and 708 to 747 ft-lbs at 3000 RPM. We have had a few issues with pulley alignment for the alternator, as Al and Robert had installed the alternator differently than it had been installed in the airplane. Parts on the way for that problem. The prop governor and other accessories lined up just right. Remember that we are going from a dry sump to a wet sump configuration, and are going to be having to re-engineer a few things to get there.
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The PSRU below, fully re-assembled and painted, ready to mount on the engine.
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Jim Stewart and Rodrigo Dill
Here we see Jim Stewart, the designer and inventor of the S-51 Mustang, on the left, consulting with Rodrigo Dill, reviewing Rod's work on putting Jim's drawings of the wing in SolidWorks. What you see here is fascinating on several levels: Jim's drawings, painstakingly produced from the 1960's through the 1990's, are now being brought into the technology of today by Rod.
Rod is close to retiring from the United States Navy, after a career in rotorwing that started with his days at the U.S. Naval Academy, has taken him all over the world (including Afghanistan), and is winding down in Pensacola. Rod has been studying and working to set up his second career, that being aircraft design. He has been working for months, getting Jim's wing into Solidworks, and finally got to travel down to central Florida this week of October 27th to meet THE MAN.
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Jim actually uses SolidWorks himself, in his recent consulting with an aerospace firm near his home in Florida, but it is, again, ironic to see Rod at the computer while Jim is sketching! Jim actually gave Rod several pointers on navigating through SolidWorks and suggestions on how to edit several illustrations to get the desired end result we wanted. Still the master, be it paper and pencil, or Solidworks on a computer!
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We begin November with Hank and Harry in Bartow, fitting and re-engineering to get the new engine in Doll; Rodrigo Dill and me getting ready to get quotes on the new tooling and forming for the new wing ribs; and Jim and Peggy cheering us on.
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540 Cubic Inch Engine in the Cradle
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Moving from November into early December, Harry and Hank had been fabricating and engineering the parts and systems that have to be changed to adapt this 540 inch Merlin Block based wet sump engine from the 588 GM Bowtie dry sump engine we pulled. The dominoes have been falling: Profanity has been profuse.
Mods to the oil system, cooling system, pulley system, several sensors, and a little re-wiring in the cockpit have been in the works. And, while eliminating some of the old wiring, we found three wires behind the instrument panel related to landing gear indicator lighting that had apparently gotten hot at some point. We also found damaged insulation on wiring for the old, abandoned Davtron squat switch Hobbs Meter system, which might have been what screwed up the other wires. All removed, and three new indicator wires will be fabricated, labelled, installed, and tested.
If you have labelled and marked your wiring as you have built, GOOD! The wiring in Doll was labelled by the Midwest Aero people who assisted in building her, and it sure was nice to be able to follow those wires through the airplane.
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We'll be working on her more this week of December 15th, hopefully firing her off by the end of the week. Will let you know how it goes.
Meanwhile, a Blessed, Merry Christmas to you followers of Christ; and Happy Holidays to the rest of you.
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