2013 Past News and Events

PROGRESS on the PSRU!

As of February 1st, we have reached agreement with a machinist and have commissioned the casting and finishing of the rear cases for the prop speed reduction unit, and, we have reached agreement with another shop to produce the center case sections from billet.  Progress has been slow, but we are pleased that we have researched these parts thoroughly and are making headway.

Jim fired her off with no problems whatsoever.

After a normal warm-up and a couple of lightly loaded mid RPM periods, he took her on up.

As he got into the higher RPM / Torque power pulls, Jim had to back off and make a few adjustments to the dyno, given we were spinning reverse rotation.  Dyno adjusted, he brought her on up into some actual take off RPM / Torque scenarios, some cruise power scenarios, with periodic slow downs.  Data was being generated and we were looking good.

After about an hour of engine time into the program, we were on our last run for the day.  The Aviator sauntered down the hall and looked out the door at the exhaust / muffler tower outside and announced that we were smoking!  We went out back and, sure enough, there was white smoke boiling out of the top of the stack!  Great!!  Blown engine already?

The engine parameters were looking fine in the test cell:  EGT's on all cylinders looked normal, oil pressure and temperature readings were fine, coolant temp and pressure were fine.  What's going on?  We decided to shut down as theories abounded, and, just to make it more fun, the ignition leads along the right cylinder bank caught fire!  Related?  Coincidental?  Not a good scene.

Grasping for any hopeful explanation, some of us theorized that perhaps something was overheated in the exhaust stack, or that maybe the ignition wires being so hot had allowed smoke to be drawn into the exhaust collector tubes.  Others offered that maybe we had an oil ring lined up wrong.  Jim and Harry agreed that we should let the headers cool down, pull them, and see what things looked like in the ports.  We did.

Everything in the exhaust ports looked FINE!  No oily cylinder, no broken valve.  Jim suggested we fire it back up with the headers removed.

We did.

The engine ran fine!  Beautiful exhaust flames shooting straight out of the engine, no smoke, no misses, parameters looked great.  No signs of any distress or damage in the powerplant.

Conclusion:  Sure enough, there was enough old material in the exhaust tower that, heated with 100LL exhaust rather than the autogas that had been going through, we had basically started a "chimney fire."

As for the ignition wires, look at the photos and you'll see how close the headers were to the double set of wires.  Jim's crew had twice, during the runs, tried to tie the leads away from the headers, but never could get the clearance we needed, thus the leads lighting off.

Jim plans to make another run next week with a different set of headers that will come further away from the block before turning down into the collector tubes.

As of now, looking back, we think we have a pretty good engine, but we went though some stress figuring that out.

What you see above is Neil Butterworth displaying the squeeze-out "rope" from the excess RTV silicone a previous owner had used in building up the PSRU.

Going back:  Hank and Harry had brought the engine back down to Bartow the week of March 11th and had begun to get the engine ready to reinstall.  I flew down on Friday the 15th to assist / be in the way.

That Saturday, we decided we ought to borescope the PSRU just to be sure nothing was amiss inside.  It had run properly, and had been thoroughly flushed, but we thought we should check anyway.  As we looked inside, the gears looked fine, the bearings looked fine, but we did see evidence of RTV squeeze out, so we took the PSRU apart, and the photo above shows what we found:  More of the same engine builder that screwed things up on the engine.  He had apparently also resealed the PSRU, bless his heart.

We removed the silicone, cleaned the components, checked the gear lash wear and pattern, pre-lubed the bearings and gears, and used Permatex High Tack and double silk threads to put the case sections back together.

The two photos above show progress as of Thursday, March 28th, where Hank has hung the prop and connected hoses and wires and accessories.  We are waiting for new pulleys and belts that will update the belt drive system to the newer radius toothed system, and waiting for the return of one of the ignition systems from factory testing.  Harry and Hank plan to fire her up for ground runs early the first week of April, still heading for an appearance at Sun n Fun.

As much as we want to display and share this plane with people at Sun n Fun, we are also working at making sure we do this engine reinstallation right, and fly it as necessary to be safe.

We'll continue to keep you posted.

During the week before Sun n Fun, Harry and Hank got the engine running, checked oil filters and systems, and figured we were ready to try a flight.  Eliot arrived and got one flight in that week before weather stopped the tests.  The first flight revealed that the engine was running rougher than desired at full power on takeoff.

CHECKED OUT

With updates and minor adjustments complete, Eliot flew a couple of more test flights, then had Hudgens come down for his transition into the Stewart S-51D, "Beautiful Doll."  Working around showers and weather during the last week of May, Cross, from his less than oppulent aft seat, put Hudgens through the paces and signed him off for solo flight.  Hudgens made his three take offs and landings on runway 9L in Bartow with Stenger watching from the golf cart.  The solo flight went fine, and Doll is now back in the hangar for installation of an electric Artificial Horizon instrument for more comfortable cross country flying.

One anomoly we are still chasing is a phenomenon where the oil pressure is dropping with altitude.  We've had input from several experts, most of whom say that such a drop makes sense in our installation, but we aren't convinced.  Oil pressure stays within a safe range for operating, but we will be investigating this further as we continue to fly.  Other S-51D builders and pilots with similar dry sump systems report that they are not seeing the same behavior in their aircraft.

We are making arrangements to have Doll at Oshkosh, AirVenture, this year.  Come see us at the Replica Fighters Association site if you can make it.

Just back from Bartow after four "sorties" over the weekend (June 22nd, 23rd).  All of the flights went well.  Flew three on Saturday during which I climbed out and loitered over the Airport at altitudes ranging from 8,500 to 10,500 feet.  These flights were intended to put more run time on the engine and systems while letting me get more familiar with operating the airplane.  Performed one power off straight ahead stall and recovery in the clean configuration, and some slow flight both clean and in the landing configuration.  The plane fell through straight ahead and recovered nicely.  Eliot wants me to spend as much time as possible with more stall work, especially practicing accelerated stalls and recoveries, reminding me that such practice is good background for developing feel and competency in the plane.  Right now, I am simply trying to get more familiar with the routine operation and stay ahead of normal flying.  I do mentally think through and touch the components I'd have to go through in certain events, such as power failures or bail out situations, keeping the mental part active.  More stall work on next trip down.

Sunday morning's flight was a short cross country down to Punta Gorda, where I made a low pass down Runway 15, just a conservative, safe flight down the runway at 500 AGL, no stupid airshow or buzz job, then back up and the return to Bartow.  Had a better chance on that trip to look at cruise performance.  Basically, at 8,500 and 7,500 feet, my groundspeed at 20" MP and 3200 RPM averaged 195 knots.  Couldn't calculate a TAS because our OAT is inop.  Was indicating around 170 kts.  Stayed back at the 20", but still had capacity for 24" at 7,500.  Fuel flow was around 20 to 21 GPH at about 100 degrees rich of peak.  I'm not a big fan of running real lean, but we'll get these parameters set a little tighter as we fly more.  Oil pressure, oil temperature, and coolant temperatures all behaved well.  We're not sure that we don't need to get the coolant warmer:  Running at about 140 degrees F right now.  Had I pushed it up to 24", might have run warmer.  Oil pressure stayed around 50 psi at altitude, running between 180 and 200 degrees F.  Oil pressure comes back up to 60 psi at the deck, so we are pretty well losing an inch per thousand feet right now.  We want to see that change and are still investigating how to control that parameter.

Basically, the airplane is doing as well as we had hoped for.  We are still on track to get her to Oshkosh next month, and have plans to showcase her up there.

Other developments:  Cliff Fitch is cutting the PSRU center cases this week, and Yankee castings has shipped the first production rear case section to Cliff for proof of fit.  Jim Stewart and Cliff have agreed on a small change to the oil feed through the center case delivering the prop control oil, and Cliff is manufacturing that part, the steel liners for the bearings, and the various oil jets required.  We'll display all the new production parts available at Oshkosh.

My youngest son, Charlie, is inventorying the airframe parts we have for the kits in Montgomery, and we'll find a way to post that inventory as soon as we can.  Meanwhile, still communicating with aluminum fabricators about component production for the airframe.

I plan to be back down in Bartow in about two and a half weeks for more flights and getting ready to ferry Doll up to OSH.  We'll update as things progress.

Got back down to Bartow Tuesday July 16th and had a nice evening flight.  Neal took some video with his camera phone and posted to YouTube.  Neal posted three videos:  S51 Flying, S51 Fly By, and S51 Landing.  He did a nice job capturing what he could without a zoom lens / camera setup.

With everything looking good, I departed Bartow the next day and ferried Doll up to Pensacola.  The flight went well, but we are still indicating cooler than we think we should on our coolant.  Oil temp and pressure were fine.  Our next move is going to be to check our temp sending unit and gage, and add another pickup / gage reading coolant in the block. 

At this point, we are planning to fly her up to Oshkosh next weekend.

This is my view out of the left wing over central Illinois on the way up to OSH at 3,000 AGL.

We had ferried Doll from Bartow to Pensacola and had done some more troubleshooting of the low coolant temperature problem.  Turned out our temperature sensing and indicating was going bad on us.  Harry had me replace the probe / gauge that senses coolant temperature coming out of the top of the intake manifold, and had me add an additional probe / gauge reading coolant temp in the block.  This setup is working very well, and answered our coolant temp mystery.  At cruise, our intake coolant discharge is running about 170 degrees F, while the coolant in the block is reading five to ten degrees cooler, which makes sense and tells us we are running the engine right where Jim Hicks wants us to.  The oil temp is running 180 most of the time.  I can tune these temperatures with amazing precision through small adjustments in the scoop outlet door, running fully closed most of the time at cruise, and fully open on taxi in.  It is nice to finally have that wrinkle ironed out.

Flew out of Pensacola Friday July 26th to Montgomery, and pulled out of Montgomery Saturday the 27th for OSH.  First stop was Evansville, Indiana.  Flew that leg in right at two hours at 8,000 and 10,000.  Doll flew just fine.  Took on forty gallons in Evansville and studied the weather pretty closely, given ceilings on up toward OSH were in the 3,000 foot range.  I had been making it a practice to stay relatively high, and not being IFR legal, I wasn't sold on continuing. 

As I thought about it and called a few people up that way for first hand observations, the weather folks began to report ceilings coming up to 4,000 overcast to broken and improving, so I figured I'd go on up.  The terrain was flat and cultivated, and I had great visibility, so I took on off out of EVV and cruised at 3,000 to 3,500 feet.  It was an absolute blast!  You could really begin to see the speed of Doll at that low an altitude, and I had safe forced landing areas the whole way up to Madison, Wisconsin, my next landing.  That leg was a lot of fun.

After fueling in Madison, another forty gallons, I went on in to OSH by the Warbird Arrival, landing on Runway 27.  A real neat trip all the way around, but it was COLD up there Saturday and Sunday.