combatpigg

My Feedback: (3)

For the pressure line.....
First you need to use Sullivan small tubing. It's able to be routed more compactly and it's just the best there is for 1/2A.
I make a fitting that is basically a "U" shaped piece.
Either a length of 3/32" brass tubing annealed and bent or brass tubing pressed into an aluminum block that has been cross drilled [lots of work].
Make the tubing long enough to pluck out from behind the engine, break it apart for filling, then cram the tubing back behind the engine to get ready for another flight.
I need to use hemostats to retrieve the pressure line from behind the engine.
If the engine is really close to the firewall, I cut a slit in the firewall that allows the pressure line to come off the backplate and make a 180 degree bend back into the engine bay where it is accessible.

fit90

I like to run the pressure line directly back through the fire wall with a one way check valve then a tee fitting then to the fuel tank. I use the line from the tee fitting for overflow and the check valve keeps it from flooding the engine crank case. There is a pic in post #47. I like to cap the over flow line with a solid aircraft rivet.

fit90

Hope the picture works,

Bob

hllywdb

Bob, that looks like a light weight alternative to messing with unhooking the line each time. Still thinking about just a fueling valve as well, I'm way under weight so far anyway. Where did you get the check valve?

Andrew

Check with [link=http://www.texastimers.com/accessories/pressure_bladders.htm]Texas Timers[/link]. They have a number of pressure fittings, but their checkvalve is not like the metal one Bob posted.

fit90

It's a Perry check valve. I got it from Tower Hobbies. Kavan also makes an aluminum check valve that is usually available through Hobby Lobby. Your GLH is really looking great. I am anxious to read the flight report.

Bob

hllywdb

Thanks Bob, is there a performance benefit to the check valve on an engine this small, such as regulating pressure?

fit90

No performance benefit. The check valve allows the pressure line to be used as the overflow for filling the tank without also filling the crankcase. I have found that some engines are a little more user friendly with a check valve, usually Cox reedies, though.

Rendegade

where do you take pressure from a reedy?

fit90

I will post an explanation after I see if the pictures are worth while.

fit90

Glad I waited. My computer does not like this site.

fit90

The picture doesn't explain squat. I definitely prefer the machined cases over the die cast cases. I like to drill through the side of the crank case in one of the spots where it is rounded on the corner for the backplate mounting screw hole. The hole should come through to the crankshaft groove on the inside of the case. Then I take some brass fuel tubing filled with solder and press it into the hole. Drill a #75 hole through the solder and you are good to go.

forsakenrider

what are you doing to your product engines that they require crank case pressure? I've always run mine with the vent tube of the tank in the prop wash.

fit90

I use pressure to help with fuel draw with enlarged intake holes and to help get a staedier needle valve setting through out the engine run.  It also makes fuel tank location less critical.  Pretty much all the same reasons as with a Tee Dee or Norvel.  Plus, it's just fun to play with the little engines and to get them to turn so fast.

Sorry for the hijack   7700

Bob

hllywdb

OK, fuselage is finished except for the nose. All pushrod tubes are in, hatch covers done for the bottom tank and elevator servo. The wing dowels are in, still need to cut out for the aileron servo. Just waiting on a couple of pictures of the crank mods from Toad to finish the engine, then I can finish the nose. I ordered the perry check valve for the pressure line. Getting close, just need to wait on a couple of things for now. Just as well, going away on a bike trip this weekend with the Mrs. anyway. Plus I need to do some work on a retract servo on one of my pattern planes before I can fly that again. No, it's not 1/2a, but I still love flying it anyway

combatpigg

My Feedback: (3)

Hey Man...I looked through my little pile of Norvel junk and couldn't find a "modded" crank to show you. I think you got the right idea about orienting the cut in the counterweight so that the piston is maybe 30 degrees shy of BDC when the notch in the counterweight is point straight up.

Rendegade

Jaysus! That looks fast just sitting there!

hllywdb

Thanks Rendegade,
While the overall is reduced to 90%, the wing frontal area is reduced by almost 60% and the fuselage by 40 to 50%. The length and stab to wing ratios remain the same. As long as I don't get too much drag it should be quick.

CP, from the pics on Toads page it looks like when the piston is at TDC the rear scoop runs from 10:00 to 9:00, looking from the rear. I am trying to get some clarification from him before doing the crank mods. Plus his pics only show the rear mods, you can't see the front of the counter weight. I just want to measure twice and grind once

hllywdb

OK, back on the project. I finished my mods on the motor with some helpfull advice from Toad. (Thanks Toad!) I went a bit conservative to start with the piston porting. I used my well-used Revelite AME RC rather than my NIB old style AME RC (In case I need a plan B). Once done with the piston I dropped a new rod and pin on it. I also didn't cut quite as deep into the front end of the shaft, but did all the other cuts as instructed. Once assembled, I quickly blew a Norvel plug and a K&B NV type button. Guess they didn't like the higher compression (1 shim). I tried 3 shims but it ran like crap.

So I dropped the Galbreath head (1 shim) on it and it ran like a charm. I started with a larger APC 4 3/4 X 4 prop to run it in. It ran just at 20k to start, but by the end of the first tank run it had jumped up to 22,200 as it started to seat. (No doubt because I used Colgate Whitening instead of the Crest Tarter Control that Toad was specific about lapping the crank with) Live and learn. So I'm guessing that with a 1/2" smaller prop and a few more runs it should hit 24k to 27k in the air, which is all I ask from an RC carb with a 4" pitch prop.

So with the motor assembled, I finished up the nose and started wrapping up loose ends like the servo rails, throttle cable, wing bolts etc... Should be almost ready to start covering soon.

combatpigg

My Feedback: (3)

Very nice. This plane will let those poor little engines "live the dream". My 1st GLH probably killed 3 or 4 TDs but they died smiling.
It would have undoubtedly been heavier with Futaba S133 servos [they were $27 each way back then and failed often], 270 nicad and dense ACE foam wing so it had fairly limited vertical with a 5x3.
Your's ought to have pretty unlimited vertical if you can keep it tracking.

hllywdb

Thanks CP,
My first one had FP-28 servos! I think my old full size 4 channel am reciever weighed twice what a new 8 channel does and 10X what the berg does. I covered it in econokote so it wouldn't melt the foam same 270 nicad and with a TD on backplate pressure it was still fast for the day. I'm thinking if I keep the rpm's down with more pitch the engine may live longer. I am going to start with a 4 1/2 X 4 (on it in the picture) and see how it does. It may take a dive to get it up on step, but I'm thinking the 4" pitch at less rpm will get me faster than a 3" anyway, so I haven't even bothered to run a rubber ducky on it.

hllywdb

More progress. Got it covered, tail feathers on and control sufaces hinged. Decided to go with a high visibily color scheme for these old eyes rather than style points.

combatpigg

My Feedback: (3)

She looks very pretty. I'm sure it will bring lots of smiles to the onlookers.

hllywdb

Thanks CP,
Belive it or not, there are a few other GLH's at my field, with TD's or AME's. One of the guys, Steve, has covering and finishing skills that leave him with planes that look like museum displays, so I am definatley out of the running for the best looking GLH. But I may have a shot at the best flying one as the others have thicker wings and are full size. You can see how small this one is next to the radio.

Max_Power

That thing is looking great! Very nice covering. Definitely on of the more difficult aspects for me but looks like you have it down. The wing looks even thinner now. Its gonna fly like a dream![8D] It looks like its staring out the window at the ray of light shining downs saying "When do I get to fly?, Cmon?" Todd