38% Bill Hempel Decathlon - Page 3 - RC Groups
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Sep 16, 2014, 09:37 AM
landings=takeoffs=good
Battman540's Avatar

Still alive.....


It has been a long time since I visited this thread and was surprised to find that it had been updated.

After I purchased Big D from Asher I started the radio change over from the 72Mhz system that Asher had installed (he kept the receivers anyway) to 2.4Ghz. I had a nice JR 12X that would be a perfect mate for Big D but I didn't have a receiver setup that was suitable. I finally settled on the Spektrum Cockpit 12 channel. It has everything in one box so it made for a simple conversion. The servos that Asher used were perfect and all high power digitals so a beefy power system would be needed. I used two 5600mah Li-ion battery packs (11.2 Ah!) so that I could fly all day without much concern. The Cockpit receiver has battery voltage monitoring as well as calculated power consumption via a LCD display. Nice! and fitting for such a well built plane.

After the radio was checked out and all of the electrons running in the proper direction I was ready for the test flight. I used my giant scale airplane hold down and anchored the plane for a test engine run. To make a long story short the engine just would not run right. I tried LOTS of things and it just didn't run very well. I pulled the engine and sent it off for repair. It came back with a clean sheet of health and ran well. I kept it a little rich for the maiden flight until I knew how well the cooling worked.

The takeoff went without a hitch and Big D flew like a over grown trainer....then the engine started surging.....throttle back and get her down! She landed just like a trainer and we started looking over the engine/carb/exhaust/ whatever to see what had happened while in flight. We couldn't see anything that was wrong. Only one thing to do was to restart and see what is going on. No amount of flipping the prop would yield any sign of life. Back home she goes.

After several months of trying to figure out why the engine was acting up and sending the carb to BME I gave up. The October aerotow was a month away and Big D was needed for duty. I ordered a DLE 170 with DLE canisters. In order to expedite the engine swap I made an adapter plate that would allow me to bolt the 170 to the same bolt pattern as the BME 150. The holes were very close and trying to get a good mount to the firewall would have been a nightmare. Anyway, the complete engine and exhaust swap took me less than a week to do.

The monster DLE roared to life and the subsequent flights were uneventful, the way they should be. After the DLE was broken in I discovered that the low speed idle was not low enough to land in a reasonable distance, it just kept flying. Adjusting the idle any lower would result in a dead stick landing. After reading through the DLE170 thread I saw that several other people had had a similar problem and the cure was simple. I replaced the DLE walbro clone carb with a genuine walbro from DA. That worked perfectly!! Now the DLE will tick over and the throttle transition is instant! Sweet!
Last edited by Battman540; Sep 16, 2014 at 10:34 AM.
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Sep 16, 2014, 10:08 AM
landings=takeoffs=good
Battman540's Avatar
I forgot to mention Big D's towing performance, heh, heh. This thing is a monster!!!!

Big D tips the scales around 42 pounds but with the power available and the huge wing area you would never know it weighs that much.

The DLE 170 swings a Falcon CF 30x13 at 6400 rpm generating over 85lb of static thrust! Big D has a ground roll of maybe 10ft and then you can point the nose vertical and watch it disappear.

I can not tell if a glider of less than 25 pounds is attached. Big D just pulls like nothing is there. Gliders in the 15-20 pound range take about 30 seconds to reach 1200-1500ft altitude. I take off and fly straight out, turn 180 and by the time we are back at the takeoff area we are at altitude. The bigger ships are no problem at all to haul up. I think Big D could alter the rotation of the earth when we run the engine up! It takes two grow men to hold her at WOT.

The canister mufflers gives off a nice mellow sound that still lets you know that a gasser is running. Most of the noise at WOT is the prop screaming for mercy!

Big D is a keeper!!!!! Thanks Asher! Like I said before, you are welcome to fly it anytime you like.

Tim

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