Author: JoeO

Re: 12000′ 4stroker climb out
Posted by: “trikebuggydelta” http://us.mc01g.mail.yahoo.com/mc/compose?to=chad@TrikeBuggy.com&Subject=trikebuggydelta
Mon Mar 2, 2009 10:01 am (PST)
Thumper High Altitude TestsI went out to El Mirage and the Flying “J” Ranch this last weekend tofly the Thumper. I wanted to launch and land the machine, maybe ahundred times, and really get a feel for it. I wanted to do some highaltitude tests, to see how high it would go and what the climb rateswould be at different altitudes. I got there Friday afternoon, and pulled the Thumper out of my shedand gave the key a try. BrBrBRrBrBr, it sounded like a jackhammer as Irealized that I should have removed the positive battery lead before Ileft last time. I pulled my Toyota over near the Thumper and gave herthe breath of life. I let the Thumper run for close to an hour,letting her charge the battery up so I had a bit of reserve. The greatthing about the Briggs & Stratton motor is that this thing just runs!You simply start it, and it just loves to run. I changed the throttlea few times to 2000 and 3000 RPM, and sometimes I would run it rightup to full (at the pitch I had the IvoProp at, it topped out at around3400 RPM – should have been around 3800), then let her rest at around1200 idling. Finally, started setting up for a flight. Wrong! Once I got in theair, I could see why the Quicksilver Ultralight pilot looked so amused- it was punchy! On the ground, it was maybe 0-4 mph, seemingly niceconditions, but once in the air it was a different story. I did a fewgo-arounds and decided that it was a bit much for me and landeduneventfully. I spent the rest of the afternoon installing the FootSteering, a Reserve Parachute, more velcro for the instruments,getting some more gas and generally tightening everything andpreparing for the evening flight. At just before sunset, I launched again, and enjoyed maybe 30 touch &go’s before it got so dark I was squinting to see. I was flying theDudek Synthesis 34 glider, and it worked beautifully with all thatThumper weight (220lbs) dangling from the lines. I trimmed this reflexglider full slow for this flight, and it inflated perfectly everytime(5 inflations) with the A-Assists and was still fast in the air.Looking at the risers, I saw that full slow is actually a bit slowerthan trim speed, so I set the trimmers at 0 (there’s actually numberson the trimmer) to put the glider at true neutral for the morning flight.Jerry Frost and Pierre Beney arrived this evening, and we spent a goodbit of time ‘Hangar Flying’ around the campfire, watching the moon setalong with that planet, really spectacular!The next morning, I warmed the Thumper up for flight. With the twistof the key, she stirred to life and seemed to be content. I let herrun for a good half hour at idle, something I would never do to any ofmy two-strokes (they would coke-up and choke) while I prepared forgoing high. I used a Flytec Vario for climb rate, a Garmin GPSmap 76for better altitude, and my iPhone with the V-Cockpit app running, avery cool airplane instrument application that uses the internal GPSfor navigation. Only problem was the iPhone was so dim that is didn’tcome out in the pictures. You can see one shot of it in the photogallery on the Altitude screen, just one of the many functions thisapp has. Check out the main screen by clicking the small icon here toyour right. It’s a really cool Application, and I had fun playing withit as I flew. There’s even graphs of the entire flight showingaltutude, speed, climb rate, heading, but no way to save them! At about 8:30, I launched from the Flying “J” Ranch at approximately2850 feet and velcro strapped the throttle at full and sat back andrelaxed, took pictures, video, and wrote down info at each 1000 feetof altitude. On this first flight, I did not write the time down, butyou can see the time on the pictures of the GPS, so it tookapproximately one hour to climb to 8000 feet and 1:25 to climb to12,000 feet. I was still climbing at 12000 feet, but very slowly, andI was cold – I didn’t wear enough layers to keep out the chill. Plus,I had not pitched the prop for maximum efficiency, at ground level itwas only 3400, and it got slower as I climbed. The motor ran beautifully the whole time, not even a hiccup. I amamazed by the four-stroker’ s incredible reliability. I could get usedto this! Trouble is, when I fly a two-stroke again, I’ll be wonderingwhen it will happen…. the inevitable motor-out. This motor is madeto run, and run, and RUN! I let it idle for a few minutes after Ireached 12K, then shut it down for the long glide back down. I reallyenjoyed the views from up high, there was snow on the nearby peaksnear San Bernadino, and I could see all the way to Tehachapi to thenorth and into the LA basin through the El Cajon Pass.