November Morning

dmccormack

Touchdown! Greaser!
Joined
May 11, 2007
Messages
10,945
Location
Lancaster County, Pennsylvania
Display Name

Display name:
Dan Mc
Yesterday was the first test flight beyond the pattern in the Chief since the extensive maintenance done during the annual inspection this November. The forecast promised light winds and mostly clear skies with a low of 32 and a high of 48. I stopped by the hangar on the way home from work Tuesday evening and set up the 100w pre-heater, prepared the cabin, and made sure everything was ready to roll Wednesday morning.


Wednesday dawned as promised, but with some local fog and widespread cloud cover. I figured it was the typical November grey and would not interfere with the flight. The airport was clear enough and the windsock was hanging limp so the forecast was close. It took a few minutes to pull the airplane out, preflight, tie it down, and prime it, and the cold engine took a few tries before chugging to life. I saved myself some work by tying the tail to the truck’s frame. Once it was putt-putting smoothly I pushed the hangar doors closed (no easy task), locked up, untied, pulled chocks, and climbed in.


Control check, radio check, trim set, doors checked on the slow taxi down to the east end of the runway. Winds are calm but a 27 departure offers a few more emergency landing options immediately after takeoff.


Run up is fine, mags check, idle good – announce, pull out into the pavement, and add power.


The tail came up quickly and the airplane was light on its feet in a couple of hundred feet. Airborne at 40, speed increases to 50. The ground falls away and the four cylinders provide a steady roar.


So far, so good.


Announce left closed traffic, turn and climb into the left downwind, check RPM, oil pressure, and level speed – all good. A shallow bank right and a steady climb while heading southbound.


The air was heavy with a fine haze under a solid layer of cloud. I tuned the radio to the Morgantown AWOS -- ceiling -2800 feet. No problem – I won't be more than 1000 AGL. The terrain straight ahead and to the west is rather featureless – a series of hills and valleys with no discernable pattern. It’s hard to know what road or what tiny hamlet is below, so I look for the Morgantown and Shinnstown powerplant plumes.


Morgantown will stay off the left wing – it sits hard against Laurel Ridge and is easy to spot. Shinnstown is south, and past my destination in Fairmont. If I keep it ahead and to the right a bit I’ll be on course. I check the compass from time to time and nudge it back to a heading of 190 degrees. I keep the radio on set to 121.15 and listen to Clarksburg Approach. It’s quiet.


Time passes slowly and every little change in sound gets my attention. Yet the engine is running steady and the airspeed indicator is solid at 85 MPH at 2500 RPM. I’ve seen 85 from time to time but not usually solo in level flight. Nice!


I check my cell phone. Dave texts: “U inbound?” I reply, “Yep. 0818 arrival”


I take the time to look around. It’s hard to see much in the haze. It’s VFR and visibility is at least seven miles, but the early morning light is diffused and the grey sky gives everything a flat appearance.


Soon I can make out the outline of a lake, then houses – Fairmont should be straight ahead. There’s the river – and the interstate. I switch to 122.8, listen, then announce 5 miles out.


I can’t see the airport yet but know where I am in relation to it. Soon I can see the bend in the river and the long stretch of pavement. I don’t hear anyone on the radio and see no activity on or near the field. Winds are calm so I head straight in, reducing power, lifting the nose, cranking up the trim -- feeling and hearing the airplane change its gait from cruise to descent.


The ground slowly grows, the numbers on the runway remain centered in my windscreen as the world spreads out from those ever-expanding numbers. It’s an optical trick that is useful – the spot that doesn’t move is where you’re heading.


Check speed – 60 MPH. The river slips below me. Now the runway is made. Power to idle, pull back a bit on the yoke – 50. The numbers flash beneath the wheels, and now the sensation of speed as the pavement slips beneath. A slight rumble in the back and then the mains rolling. Keep it straight, no brakes, back pressure, ok.


I release the back pressure and the airplane rolls freely along the runway the other thousand feet to the parking spot. I pull the plane in to a tie-down spot marked with new ropes, switch off fuel, run up to 1500 RPM, get straight, pull back to 1000, the engine coughs, dies. Mags and radio off, unbuckle, unload, tie down, and walk over to the car.


“Good morning, Dave!”


“Hey, Dan…”


I check my watch – 0818.


Sometimes I guess well.
 
Nice writeup, Dan. :)

What's the advantage of switching to fuel off rather than just going for the mags? Is it a good thing to burn the fuel sitting in the carb before shutdown?
 
Nice writeup, Dan. :)

What's the advantage of switching to fuel off rather than just going for the mags? Is it a good thing to burn the fuel sitting in the carb before shutdown?

Thanks!

Yes -- in this setup the carb is mounted on the bottom of the oil pan, so fuel is drawn in via gravity. By shutting the fuel off all the fuel remaining in the line from the shut off valve all the way to the carb is used up.

This *should* reduce the hazard of a hot mag should the prop be moved (I know, I know, but these airplanes run on OWT and MMO :D).

I only use this technique for a stop more than and hour. Any less and it's mags off.
 
Thanks!

Yes -- in this setup the carb is mounted on the bottom of the oil pan, so fuel is drawn in via gravity. By shutting the fuel off all the fuel remaining in the line from the shut off valve all the way to the carb is used up.

This *should* reduce the hazard of a hot mag should the prop be moved (I know, I know, but these airplanes run on OWT and MMO :D).

I only use this technique for a stop more than and hour. Any less and it's mags off.

Ahh, makes sense. Have a good one!
 
Thanks!

Yes -- in this setup the carb is mounted on the bottom of the oil pan, so fuel is drawn in via gravity. By shutting the fuel off all the fuel remaining in the line from the shut off valve all the way to the carb is used up.

This *should* reduce the hazard of a hot mag should the prop be moved (I know, I know, but these airplanes run on OWT and MMO :D).

I only use this technique for a stop more than and hour. Any less and it's mags off.

Doesn't reduce the hazard of a hot mag but it does remove all the fuel vapors from the cylinders so the engine can't fire if a mag is left on or the P-lead's broken. Without the idle cutoff found on newer carbs, that's all we can do. I have the same carb, with the mixture control (on a homebuilt, so I made the mixture parts and put them into the place for them. Those parts are really rare and really expensive) but it's a back-suction affair that has no effect on mixture or fuel flow at low power settings.

The idle cutoff mixture control uses a small valve that actually meters the fuel and can shut it off altogether. The back-suction type applies a bit of venturi vacuum to the float bowl to hold back on the fuel, reducing its flow and leaning the mixture.

Those old Strombergs work better than the "modern" carbs we put up with on newer airplanes. Rotten mixture homogeneity, poor atomization, seeping bowl gaskets, stumbly at idle, on and on. Tempest bought the line from Precision Airmotive and I hope they fix the things. If Bendix/Stromberg could make a really fine caburetor 60 and 70 years ago, why can't we get a fine carb now? Thousands of airplanes that use carbs and we can't get consistent quality. Sorry for the rant but I've had to repace at least three carbs that came with Lyc factory remans in the last year.

Dan
 
Doesn't reduce the hazard of a hot mag but it does remove all the fuel vapors from the cylinders so the engine can't fire if a mag is left on or the P-lead's broken. Without the idle cutoff found on newer carbs, that's all we can do. I have the same carb, with the mixture control (on a homebuilt, so I made the mixture parts and put them into the place for them. Those parts are really rare and really expensive) but it's a back-suction affair that has no effect on mixture or fuel flow at low power settings.

The idle cutoff mixture control uses a small valve that actually meters the fuel and can shut it off altogether. The back-suction type applies a bit of venturi vacuum to the float bowl to hold back on the fuel, reducing its flow and leaning the mixture.

Those old Strombergs work better than the "modern" carbs we put up with on newer airplanes. Rotten mixture homogeneity, poor atomization, seeping bowl gaskets, stumbly at idle, on and on. Tempest bought the line from Precision Airmotive and I hope they fix the things. If Bendix/Stromberg could make a really fine caburetor 60 and 70 years ago, why can't we get a fine carb now? Thousands of airplanes that use carbs and we can't get consistent quality. Sorry for the rant but I've had to repace at least three carbs that came with Lyc factory remans in the last year.

Dan

I don't have mixture control -- fuel shut off only, so the fuel drains from the cutoff through the gasculator down the fuel line into the carb. That's about 5 minutes at 1000 RPM and enough to get me from the main taxiway back to my hangar if I don't have to maneuver around anyone.

Agree on the simplicity and efficiency of these old carbs. I am using tempest plugs and have been happy so far. No carb maintenance yet, but will keep PA in mind.
 
I don't have mixture control -- fuel shut off only, so the fuel drains from the cutoff through the gasculator down the fuel line into the carb. That's about 5 minutes at 1000 RPM and enough to get me from the main taxiway back to my hangar if I don't have to maneuver around anyone.

Agree on the simplicity and efficiency of these old carbs. I am using tempest plugs and have been happy so far. No carb maintenance yet, but will keep PA in mind.

Not Precision Airmotive. I meant that Tempest bought the line we know as Marvel Schebler, aka the Marvellous Dribbler, that has also been built by Facet, and was last built by Precision, under whom the quality seemed to suffer. You don't want one of those MA3 carbs on your Chief, believe me, if you have a Stromberg now. Just take a look at the MA3 & MA4 AD history. And the ADs only addressed the dangerous stuff, not the irritating stuff. Lots of irritating stuff.

Dan
 
Back
Top