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Preparation for 2010 Euro SAM RC Champs
The Europe Target
Previously I described my desire to take the Giant to Europe and compete in the Texaco event, to which end I purchased the MVVS 61 diesel, popular with the Euro competitors. Well, this is still my goal and much of my thinking over the winter is on just how to do it. My primary concern has been with the shipping and associated issues. I have had good results in shipping my models as checked luggage in hard sided golf bag containers. Although the US security folks usually open the box it usually survives, albeit with the occasional damage to the models, but on the whole it has worked. Oh yes, on occasion the box does not arrive on the same day as I, but it has always followed me a day or so later and I usually accommodate this eventuality by staying a few days at the arrival city. The Giant with its 18 inch chord wing and tail will not fit in a regular golf bag, but lo and behold, SKB makes a double sized golf bag container, and it just accommodates the Giant aerosurfaces, actually with room to spare, but not enough room for the fuselage. So I bought one and shipped the wings and tails back to Philadelphia from LA. The good news is it worked, the bad news is the eager young Southwest check-in staff measured it and declared it to be oversized and charged me $50 one way. Not all bad as they did take it, but the trouble is, the fuselage needs one too as the roughly 9 inch square pieces don't fit in a single sized box.
So, do I buy another one? What will the airlines do when I ship two to Europe? Will they be oversized and charged as such? Worse, will they reject them altogether? Will they take them to Europe and refuse to bring them back? Trouble is, every trip is different and you deal with a new agent at every check-in. Having got over that problem, how will I handle these two boxes as well as two suitcases and two carry on bags? Oh, I didn't mention that we, our US contingent, Jean and I, will fly to London then take a cruise of the Baltic before flying to Prague and driving to the meet. We need to take quite a bundle of cloths for the cruise and possible inclement weather in the Baltic.
Long story short, I began to look at making an airline spec; 80 inch girth plus length, single box to accommodate the model. Could I fit all the parts in such a box? The answer is a conditional "yes". Conditional because once I make the width accommodate the wing and tail chord, then stack the parts including the two fuselage halves, it is about 19" x 18" leaving only 43" for the length. At this length four parts don't fit; the outboard wing panels are too long, by about 3" ~ no big deal to make them removable, but the fuselage parts don't fit either. The aft part can be cut aft of the structural areas where the flying tail parts attach. I can make the aft end a removable fairing. But the forward fuselage is another matter. Oh, I also need to take a Speed 400 Stardust Special, but I thought that might fit in the spare spaces, and it does. Here is the trial fit. The short fat tube is a weight to hold the Stardust Special fuselage in place temporarily. You can see the parts fit the cross section but peek out of the end at this point.
I started the box fabrication for a trial fit and initially found it too short so I added a riser to allow for a little slack which I will fill with padding. I will leave the top off until I get all the packing organized and support members installed. The SS fuselage nests into a pair of foam blocks glued to the sides. I plan to add such padding and fitments as necessary to get the thing properly restrained and located, then install the top. Now to tackle the forward fuselage.
My initial thinking was to cut off the nose forward of the bulkhead but the structural implications are daunting, particularly with the MVVS installation and all its vibration etc. I have thought it through and decided to make another fuselage joint, identical to the current joint, but in the second bay back from the bulkhead. Since the nose is smaller in cross section than the fuselage shell at station 3 I will be able to nest the parts in the box. So, off to make the joint. don't you just love to tackle a piece for which you previously solved the problems?
Here is the two-piece forward fuselage;
And it fits the box, and miracles, there is also a really good place to stash the radio.
Ok, what's next? Probably the aft fuselage and then the wing tips, then try a final box fit before putting on the lid and latches.
Then on to finish the forward fuselage covering etc.
I quickly finished the structure and covered it before making a new cabane structure. You may remember in Nevada the cabane survived but the aluminum uprights were significantly bent, some of them right at the bolt hole locations. No way would I fly with these even though they were straightened. I made new ones and then carefully analyzed the best incidence for cruise flight. You may remember I suspected incorrect rigging of the cabane as the primary cause of poor glide performance in the original developments. So this was the opportunity to get it right.
Ok, so I did all those things and progressed a good deal towards the Euro goals. I also began the development of the diesel propulsion for the Euro Texaco event. My son asked me to go drag racing with him the other Friday night and I realized it was an ideal opportunity to break in the MVVS. It would make less noise than anything there. And so I did but I was not able to back out the contrapiston to get the right settngs. Consequently I running was mostly done at high temperatures over compressed. Although I took it from high speed rich to idle and back it never really cooled down and after a subsequent disassembly I found it was still a little tight. Meanwhile Allan Laycock had been providing advice based on Aussie developments and further, sent me his MDS 61 diesel to try.
The Euro rules specify a two-cell LiPo battery of any capacity and on a power basis I need to pull a lot of amps. My four pound Stardust Special pulled in the region of 90 amps with the Neu 1506/1Y motor and 6.7:1 gearbox. To achieve the same power and rate of climb I would need to pull two and a half times this; no way! Well, there is a way; spend money, lots of money. But that is not on as they say in England, but I want to fly the Giant in the electric event even if it is just for fun, so what to do?
The high power system I put together for the 2009 SAM Champs on the El Dorado dry lake used the same Neu motor but with an additional 2:1 gearbox added in series with the standard 6.7:1 for a total reduction of 13.4:1 On El Dorado I used 36 NiCad batteries arranged in three parallel sets of twelve pulling about 80 amps at about 12 volts for almost a kilowatt. I spoke with a Castle Creations tech rep at the AMA show and he told me they see over 130 amps on the 125 amp controller I use so perhaps I could pull 130 amps and about a loaded 6 volts from a quality LiPo for a bit less than 600 watts. But although the ESC may take that there is the question of the gearbox. Amps equals torque and although the gearbox handles 80 amps I strongly doubt it is up to much more. How to find out? Test it, so I did.
Of course I had been running endless analyses of motor/gearbox/battery and propeller alternatives but first I needed to check out the rebuilt Giant, so I selected what seemed to be a modest setup with an 15 x 10 prop and one two-cell NeuEnergy 4900 mah 20C LiPo. In the event it hardly had enough power to take off and I aborted the flight straight down the strip. What went wrong? I thought the battery might be at fault so I tried an identical one with the same results! I needed to get in this test flight so we councilled. I didn't know what was wrong but certainly it was way down on power, but all I needed was a flight. So I thought why not parallel the two two-cell identical batteries and go easy on the throttle. Certainly the ESC could take it. And so we did and made an excellent flight. Indeed it wouldn't come down. Clearly the lower weight allowed by the LiPo batteries helped but I think the re-set cabane incidence it the key. I am glad I took the time to set it up correctly.
But why did I have the motor troubles? Motocalc has always given me pretty accurate results. Eventually I found the reason, in doing some analysis for the club Foam Construction Workshop I was analyzing some alternative designs including some twin motor arrangements. I had left the setting for two parallel motors! Once I corrected this I began to make real progress on a Euro design.
The issue was how much torque could the gearbox stand and what props would it turn. I did some ground testing with a variety of props based on three different sets of Rudy Freudenthaler's graphite blades. The table below shows the progression to steadily larger props. Motocalc indicated a 32 x 20 prop should operate at about 130 amps and yield the maximum rate of climb but would the gearbox stand the loads? I made a series of middle parts twisting them to achieve the desired pitch. As you see I made a mistake with the first 32 inch prop with the 28 x 12 blades but adding too much twist and drawing over 160 amps for a moment! Incidentally, I am reading amps with a Craftsman clamp-on ammeter. My efforts to read these high currents with a conventional Wattmeter or the Hyperion Emeter were fraught with problems from the resistance increase arising from the additional connectors to insert the meter into the circuit. The clamp-on device works perfectly.
|Neu 1506/1Y 13.4:1 gearbox, CC 125 amp ESC|
|Prop||26 in dia (RF 20x13 blades) middle part twist +10 degrees|
|Battery||Volts Resting||Volts loaded||Amps||rpm|
|Prop||26 in dia (RF 23x142 blades) Middle part twist +9 degrees|
|Prop||28 in dia (RF 23x142 blades) Middle part twist +9 degrees|
|Prop||28 in dia (RF 28x142 blades) Middle part twist +5 degrees|
|Prop||32 in dia (RF 28x142 blades) Middle part twist +6 degrees|
|Prop||32 in dia (RF 28x142 blades) Middle part twist +0 degrees|
Well the gearbox survived the ground testing so now for the flight test with the 32 x 20 prop. I made two flights, the first a ten second or so climb with a quick return to land and check the motor, ESC and battery temperatures. They were just warm, so I decided to make another flight, this time for about thirty seconds. The climb is good and steady and the 25 second climb took me right into an excellent thermal which I played for a while until the model was getting high and downwind, so I brought it back to make a safe landing from an excellent test. The glide was excellent despite flying without the cowl, a precaution to assist with temperature control. I don't think this is necessary for the competition flying.
Now to work on the engine powered configurations. Looking at the Euro calendar I realized with a suitable engine I could also fly in the Old Timer Limited Engine Run event and I asked Ed Hamler if he had a spare Anderson Spitfire to loan me. He not only had a spare but was delighted to mail it to me and I began to plan the installation. Both the Texaco diesels and the Anderson Spitfire are much heavier than the electric motor setup, but then the model must fly at 10 ounces per square foot wing loading for them vice eight ounces for the electric. Trouble is, the heavy engines make the model nose heavy so it will be a challenge to balance them. I will move the radio battery from the firewall back to the stab area in the fuselage but more ballast will be necessary and much of it in the tail cone. Here are the three propulsion systems for the Euros.
Meanwhile I finished the shipping box, varnished it and affixed the shipping labels
I have been working on the diesels. To recap, the MVVS diesel needed breaking in. The propper way to do this is to give is a whole series of short runs cooling between each. Initially you run rich bring it to temperature and then shut it down to cool. Then you repeat the process and lean it out some while at high speed and listen to the exhaust note and rpm. If it begins to slow and get hot you shut it down to cool and try again until it takes the high speed lean run, not over lean but leaned to peak rpm. Then you need to do this with the prop and fuel you intend to use and make sure it doesn't get too hot when peaked; specifically it doesn't slow down and labor.
Ok, so much for the right way, but the MVVS had this problem that you couldn't start it from cold without cranking three or more turns of compression. Then as it came to temperature it would tighten the contrapiston so you couldn't back it out any more. All this drama made it difficult to make the desired cold to hot runs. What was particularly troubling was my inablility to back the compression sufficiently to get on the back side of the compression; to the state where it would rum...rum...rum... etc.
I have done a good deal of work in this area including a long series of communications with Allan Laycock in Australia. I will report on all this engine work eventually but suffice it to say I couldn't make the MVVS nor MDS work for various reasons, mostly running out of time, but I did manage to fly the Giant on my old Irvine 40 diesel, the engine I have used in the 6 pound Lanzo Bomber. It was just one flight and the engine run was not good but fly it did so I packed it for Europe. Also, because enough is never enough I looked at what other events I might fly with the Giant and when Ed Hamler offered a loan of his spare Anderson Spitfire I made a mount for that too so I could fly in the Old Timer LER event.
The Euro story is a successful shipping of the box there and back but my wife became unwell and we waived off the Czech Champs, returning to the US and other commitments. No further development or flying took place prior to the Muncie Champs. Indeed, we just loaded the Euro box with the canopy, some tools a gallon of diesel fuel; yuk! And some new batteries for the ETexaco event.
2010 Muncie Champs; The first Giant event took place on the Tuesday in perfect weather. LMR allows a 90 second climb with a ten minute max. Best two of four flights count. The model climbed very well to altitude and I scored two easy maxes and waited the rest of the day for the flyoff. The flyoff with seven contestants including Jack Hiner and the Kentucky Posse of Jay Burkart, Kent Meglemry and Henry Gullett all flew 1000+ sq inch Lanzo Airbornes and Dale Tower flew a huge Stardust Special. This must be the era of large models, and it was just as well because the Airbornes all flew almost OOS overhead along with nine buzzards. I followed. Jay later informed me he was at 3300 feet. After a long period where we flew from lift to lift, each covering the other, the lift diminished and one of the high guys transited to another part of the sky, I followed. But I found a small patch of lift that the others did not and rode it steadily higher and downwind for the win and high time of the meet at 58+ minutes. The Giant was behaving perfectly.
The next Giant event was Glow Texaco with the Irvine 40 diesel. To meet the 10 oz wing loading I had to add two+ pounds of ballast for a gross weight of twelve pounds. Now in the basic Texaco events you get 4cc of fuel per pound up to seven pounds for a maximum of 28cc. This puts the twelve pound plane at a disadvantage but I was only flying the event to gain experience for Europe where it would get about this same amount.
Diesels can be a pain in the butt, particularly when you run them on the ragged edge of load and lean mixture.
Well, the first engine setting was a disaster because I overheated it when stopping to refill the tank. Anyway eventually I made a fair flight followed by a really screwed up one when I had to land it in the bean field! On the third and final flight I immediately hooked into a great thermal and being coached by Dale Tower followed it downwind to great altitude. But at some point I slipped up as it stalled and dived almost vertically till I caught it at about half the altitude. From there it was a gently glide back to the landing spot for second place. But … you know, woulda coulda shoulda …..
The next event on Friday was the Electric Texaco. This class specifies a minimum wing loading of 8 ounces per square foot, and the gas classes are 10 ounces so with 20 sq feet of wing area the electric must weigh a minimum of ten pounds. However, the electric event also specifies a weight for each battery capacity and this was a problem. The Giant Texaco motor and gearbox was one I used with a four pound Stardust Special. In the original Giant design I powered this same motor with more NiCad cells to increase the voltage and power necessary to fly the larger model. But this year I wanted to fly with LiPo batteries and the smallest three cell 45C LiPo I could buy ended up at 3800 mah. With this battery I needed to add over four pounds of ballast. So an additional large adjustable wrench was added. But the model flew poorly at this weight with this propulsion system turning a very disappointing first flight. So I set it aside and made the configuration change to fly Classic Texaco with the1930s Forster 99 ignition engine.
I had not run the Forster in the Giant since I don’t know when, so at first it was not quite on song. The first flight was quite disappointing. But guru and former owner of this engine Don Bekins was there to help and soon he had it singing just right and I made a decent second flight. This event is best flight of three counts so I had one in the bag. But my real interest was Electric Texaco and I was stumped. But flying buddy and last year’s Electric Grand Champion, Dick Bartkowski, was thinking (he always is) and said why don’t you put the LMR motor back in with a smaller prop? We had Motocalc on the laptop and how about that, it indicated that we might get decent performance on the two cell LiPo that would let us fly at ten pounds, but we needed a different prop to either one I had brought. I make these special props using the very high quality Aeronaut blades with different custom made aluminum middle pieces. The LMR prop is a 32 x 17 which is made using the Aeronaut graphite 28 x 12 blades. I had another middle piece that would make a 28 inch prop with these blades but it would be only about 12 inch pitch. The model would not fly on such a prop and we needed more pitch. At home I twist these parts in a big vice using a big wrench on the other end. What to do? Chuck Kime found that he could jamb one end in the chain link fence fitting and twist with a big adjustable wrench to some higher pitch; what we didn’t know but we did know it would fly. So Chuck removed the Forster and installed the big electric motor. We finished this with only fifteen minutes left to put up the last Electric Texaco flight, with an untested propulsion system and prop! It took off easily as I expected but I cut back the throttle to a cruise climb. As I was climbing out Dick pointed out that one flyer from an earlier gas flyoff was waaaaay high directly above us so I maneuvered into that piece of sky and climbed steadily. I hooked into the thermal and rode it for a while until it dissipated and I came down into the landing region. Just as I was planning the final approach over the end of the macadam runway the model twitched and I cranked it over into a slight thermal. I rode it for a little bit being coached as to how to center the model in the lift by Don Bekins.
And wouldn’t you know it, that thermal grew and grew until the model was so high and downwind that it was becoming hard to see. I was now the only model in the sky so I asked what time I had to beat; who has the best time? I was told that the best time was 37 minutes or so and I was already at 33. I could drop straight down and beat that time but of course I had to get back to the landing area, so I abandoned the magic thermal and cranked in down trim to beat a hasty path back to the landing area. At some point in this process the word came that I was given the wrong information and that Jack Hiner had made a 54 + minute flight earlier in the day. Darn! Or worse! I had abandoned that great thermal and wasted time by diving down, but it was too late to recover and I landed for second place in almost 50 minutes. What a flight, what a meet, what a model!
What next? Take a break and start development for the 2011 Euros in San Marino and Champs in Boulder City. Oh, yes, and I added a PAW 60 Texaco Diesel to the mix!
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