HK600GT Gasser Conversion

Yeah' i only had collective pitch and tail control. Cyclic was the camera hand. But it wont stay up for very long, the engine will bog and as you add more collective it bogs more. But the boat guys get a lot of power out of that engine, so with a little bit of help it will be just fine i think.

Are you looking for some more RPM, or torque?

Well, the current RPM at no load is good, so more top end torque would be good. Right now the engine is set up from the factory for two things, value and emissions. The stock exhausts are very resrtictive and the carbs are too small, compression is low and ignition timing is not great. I just ordered a bigger chainsaw carb off ebay and am designing a new exhaust system. I might take .010" off the cylinder for more compression and will probably lighten and stuff the crank case area. Not sure how much I will port it, but some mild port timing can't hurt.

Bogging is such an "Fugly" word, eh

Torque issue = A gearing issue, increasing the RPM via the motor pinion will decrease the available torque!

Certainly increasing the RPM via better Air/Gas/Exhaust flow would be a asset but I would also consider or look to teh gearing (both main and/or motor pinion) and see if we can or can't make any improvements there

... and that's about as diplomatic as I can be well maybe except to say "for our Sercher'n Lurkers"

    [shadow=Orange,left]w00d[/shadow][shadow=red,left][/shadow]

Hey PP, I've looked back through the posts but did not notice what type blades you are using other than 600mm.
You have probably already considered a flat bottom blade for a little more lift?

My issue is simply a matter of overall power. A general rule of thumb to follow with Helicopter engineering is that it takes 1 Horsepower for every 10 pounds of weight that you are flying. The most efficient helicopter ever built was the Flettner FL-282 and it could lift about 14.7 Lbs per HP (intermeshing co-axial design). The bigger and more powerful the helicopter gets the less it can lift, the S-64 skycrane with 5 blades and 8,000 HP will only lift 5-6 Lbs per HP, with the smaller stuff, Bell Jet Rangers, Robinson R22, Etc are all locked in at 10 Lbs to the HP (tail rotor design).

The original convention used to determine RC helicopter size was energy used in flight, a 450 used 450 watts, 600 used 600 watts, etc. 600 watts converts to .8 HP, keep in mind that electric has a higher effective output than gas so it would take something like 1 HP or better to keep up with the .8 electric motor.

My 600 weighs 12 Lbs and has .7 HP in stock form, so engine mods to get one to one and a half HP are required. I will attempt this in stages:

Stage 1: Carburetor, from 9MM bore to 12MM bore with mixture adjustments and custom CNC machined intake manifold. Open bottom of intake port by .010", de burr the rest of the port. Open top of exhaust port by .010", de burr rest of port. Build new exhaust pipe and install. Open crankcase cover and remove optional starter gear (steel weight), stuff crankcase with .125" shim. De burr crankcase and intake transfer ports. Re install cylinder with thinner gasket, check squish band clearance. Assemble and test fly.

Stage 2: Remove squish band, machine .020" at a time from cylinder to achieve 135 - 145 Lbs of compression, advance timing to 20 degrees BTDC. Run high octane fuel. Machine transfer ports open. Blueprint port timing to achieve maximum opening times.

Stage 3: Junk the piece of crap and buy a Stihl 026 chainsaw that has 3 HP at 14,000 RPM, strip away un needed junk, install, change pinion gearing and fly! (I have a Stihl 064 in my garage that puts out 7 HP, Hmmmmmmm?)

Alright, you've got determination. 
And I believe this bird is going to fly one way or another.    ;D

"The Shawshank Redemption" Is one of my favorite movies 

+1  ;D

Quick update, I installed the new larger carburator and wanted to see what difference it made, finally got it tuned somewhat smooth and took it outside to test. I also picked up an ORANGE Rx to free up my 450 Rx, I had heard bad things about them (ORANGE) but figured it would be ok since test flying is right in front of me for now. The helo still struggled but after the right tweaking I got it to finally sustain it's first flight, got it into about a 3' hover for maybe 3-4 seconds when all of a sudden it went crazy, rolled over to the left, then the right, then went spinning out of control, I lowered the throttle and thought, well this thing is toast, as I expected it to land on it's side and blow up in front of me for some reason just as the blade tips were about to hit the ground it jerked back up right and bounced on it's skids. As the blades were spinning down with the engine at an idle it tried to jerk full cyclic to the left on it's own but there was not enough energy left in the rotor head to tip it fully over. When I got it shut down, the ORANGE Rx was blinking that it lost signal from the radio. So that $5.00 POS is coming off and a real spektrum Rx will go in it's place!

I still need to do exhaust work on this for it to really work, but the results of the engine performance are promising at this point.

Just placed a bid on a AR6200 Rx, should do the trick I hope.......

Sorry to hear about the receiver glitch.  It sounds like you didn't break anything so that's always good.  I know some of the guys at the weekly fun-fly use those Orange receivers and have good things to say about them.  Maybe you got a bad one.  Had you done a range test with it?