Soaring

[MRC01]

Diamond Aircraft may be the current non-turbine exception.
It's a Mercedes Diesel before modification. Runs on Jet-A.
It was slated for the Cirrus, but heavy, and required a redesign of the airframe, so they declined.
...

More about that engine, a heavily modified Mercedes that had numerous problems in its previous iteration with Theilert.

Thielert Centurion - Wikipedia

en.wikipedia.org

It is not direct drive, but geared from crankshaft to prop, which historically has been problematic with piston aviation engines.

... Electrification will likely short circuit any other makers in the not so distant future.

Indeed. Also, the phase-out of leaded avgas will make the existing engines burn cleaner and last longer - less oil contamination and longer lasting valvetrains.

 

[Blumlein 88]

We'll soon have to have a thread. EV aircraft, batteries, subsidies (no politics).

 

[Doodski]

We'll soon have to have a thread. EV aircraft, batteries, subsidies (no politics).

RFLMA...

 

[Timcognito]

As a ME, I do like learning about all these aircraft engines and was surpised to hear abut " magneto firing" though. My '70 Husavarna 250 used give me fits with magneto problems. Still I can not get into a small plane but love to see others do it because I love machines.

 

[MRC01]

As a ME, I do like learning about all these aircraft engines and was surpised to hear abut " magneto firing" though. My '70 Husavarna 250 used give me fits with magneto problems. Still I can not get into a small plane but love to see others do it because I love machines.

Magneto firing is for redundancy and reliability. Most certified aircraft piston engines have 2 spark plugs for each cylinder, and 2 magnetos, the upper plugs fired by one magneto, the lower plugs by the other. If the aircraft electrical system fails, the engine keeps running. If one magneto fails, the engine keeps running.
There are certified modifications allowing electronic ignition, but usually only to replace 1 magneto while keeping the other. This gives marginal improvements to efficiency and power while preserving redundancy and reliability.

If you want to read more about these engines, the O-360-A4M in my airplane is one of the most common.

 

[thecheapseats]

Magneto firing is for redundancy and reliability. Most certified aircraft piston engines have 2 spark plugs for each cylinder, and 2 magnetos, the upper plugs fired by one magneto, the lower plugs by the other. If the aircraft electrical system fails, the engine keeps running. If one magneto fails, the engine keeps running.
There are certified modifications allowing electronic ignition, but usually only to replace 1 magneto while keeping the other. This gives marginal improvements to efficiency and power while preserving redundancy and reliability.

If you want to read more about these engines, the O-360-A4M in my airplane is one of the most common.

yep - magnetos and dual plugs - a fascinating ignition system so planes don't fall out of the sky... I learned a lot partway through an A&P apprenticeship (as a backup career in case the career I really wanted didn't pan out) - and I recall being fascinated by those small continental and lycoming engines which bore a striking resemblance - minus the redundancy of course - to the 180-degree opposed, air-cooled VW engine in my '65 vw surf van...

 

[Timcognito]

 

[MRC01]

"Once you have tasted flight, you will forever walk the earth with your eyes turned skyward..."
Translation: Flying airplanes is a disease for which the only cure is poverty.

 

[DonH56]

"Once you have tasted flight, you will forever walk the earth with your eyes turned skyward..."
Translation: Flying airplanes is a disease for which the only cure is poverty.

Luckily I never got my pilot's license, a dream of my wife and I from years ago. Fortunately hobbies like audio, music (performing instrumentalist), off-roading, photography, woodworking, and so forth are more than up to fulfilling the poverty aspect.

 

[RayDunzl]

Grounded...

The Cessna tow plane is in Georgia supporting a contest at Cordele.

The Pawnee tow plane developed a "vibration" during a tow, and ended up in the hangar.

It's a six-cylinder Lycoming, and the center cylinder on the left popped its upper retaining studs.

They pulled the cylinder yesterday, said it all looks good, will have the cylinder tested for invisible damage, and go from there.

Hope the broken studs come out with no issue.

Big job. Many pieces had to come off to get to it.

I wonder what kind of torque wrench will get itself into that small space.

That probably explains the pesky oil leak that couldn't be tracked down.

 

[Blumlein 88]

Look at this video. Quality is not great, but just past the 6:30 mark you'll see an odd shaped extension for the torque wrench.

Oops, this is a not the same engine, but I bet they have a similar device for the Lycoming. A variety of crow's feet adapters are needed for various tasks on aircraft engines.

 

[MRC01]

... The Pawnee tow plane developed a "vibration" during a tow, and ended up in the hangar.
It's a six-cylinder Lycoming, and the center cylinder on the left popped its upper retaining studs.
They pulled the cylinder yesterday, said it all looks good, will have the cylinder tested for invisible damage, and go from there.

With the cylinder removed, they should (almost certainly will) inspect the cam lobes and lifters. With a Lycoming, it's the only time you can do that. And the Lycoming cam is above the crankshaft, unlike Continentals where it is below. This makes the Lycoming cam more susceptible to corrosion if it is not flown regularly.

I learned this all the hard way, from the Lycoming O-320-D2G that used to power my airplane. At annual, one cylinder had only 40 PSI of compression. Turned out to be a leaky valve. But while the cylinder was out, we noticed the cam lobe was corroded. The only way to fix that is to split the case, so you might as well overhaul the engine, so you might as well replace it with an O-360-A4M, which is how my airplane engine got upgraded.

 

[thecheapseats]

With the cylinder removed, they should (almost certainly will) inspect the cam lobes and lifters. With a Lycoming, it's the only time you can do that. And the Lycoming cam is above the crankshaft, unlike Continentals where it is below. This makes the Lycoming cam more susceptible to corrosion if it is not flown regularly.

I learned this all the hard way, from the Lycoming O-320-D2G that used to power my airplane. At annual, one cylinder had only 40 PSI of compression. Turned out to be a leaky valve. But while the cylinder was out, we noticed the cam lobe was corroded. The only way to fix that is to split the case, so you might as well overhaul the engine, so you might as well replace it with an O-360-A4M, which is how my airplane engine got upgraded.

if you have time to spare, go by air...

 

[RayDunzl]

The opposite cylinder (and all the parts that prevent its removal) will have to come off, because the "studs" go all the way through the engine. The cylinders hold the crankcase halves together.

https://www.lycoming.com/sites/default/files/attachments/SI1029D%2520Bolts%252C%2520Crankcase%252C%2520Tightening%2520Procedures%2520for%2520Thru-Studs%2520and%2520.pdf

I'm not involved unless I happen to be standing there and somebody says "Hand me a rag".

No fly this week...

Number 2 towplane is in Cordele Georigia for another ten days or so.

 

[MRC01]

... I'm not involved unless I happen to be standing there and somebody says "Hand me a rag".

Sounds fun.

No fly this week...

That does not sound fun. I just got my plane back in service after 2 months of doing nothing but short test flights to troubleshoot the ADS-B system.

 

[RayDunzl]

Naviter SeeYou software for phones, an in-flight screeshot:

The colors on the flight track show where you were rising (red) or sinking (blue/green). The arrow is the plane. The display can rotate (follow the plane) or remain stuck on North at the top.

It calculates the wind based on your drift while circling in a thermal, in this case 9mph just North of East.

Since the phone has a barometric sensor, I can get two altitudes, pressure and GPS. The pressure altitude well matches the altimeter in the glider, GPS altitude is almost always a little higher.

My "target" is the airport, and I want to arrive there at no less than 2100 feet, bottom line shows the distance, required glide ratio, and expected arrival "buffer" - arrival is how high above (or below) the 2100 foot "safety altitude" I might arrive if I turned back.

The recent glide ratio was 34:1 - travel 34 feet forward for one foot drop, when not circling.

"Last Thermal" is the average rise the last time circling, with the altitude gained above that.

The Vario is the current rise/drop in feet perminute, and AVG vario averages that over a short period of time.

The purple dotted line points torward the target, in this case the airport.

The dashed black line shows the heading to the next turnpoint when following a route, and a thin solid line showing where I'm actually headed, useful and visible when zoomed out more.

Anyway, a handy tool, and cheap.

Phone software lacks "certification" to make an "official" flight, like earning your Boy Scout Merit badges (altitude gain, duration, distance) and can't be used in "official" contests.

Next week is Contest week in Cordele, Georgia.

Cordele soaring contest, region v south

The official website of the Cordele Soaring Contest Region V South. Information about flying, accommodation and more.

www.flycordele.com

 

[MRC01]

... The recent glide ratio was 34:1 - travel 34 feet forward for one foot drop, when not circling. ...

Impressive! Is that at the optimal airspeed Vldmax?
The best my 172 will do is 10:1 at Vldmax. That's better than a flying squirrel, but not by much.

 

[Blumlein 88]

Impressive! Is that at the optimal airspeed Vldmax?
The best my 172 will do is 10:1 at Vldmax. That's better than a flying squirrel, but not by much.

It has been a long, long time since I flew a 172. Am I remembering right that the best speed for this is 60 knots? Or was it 65 knots (maybe a 152 was 60 knots)?

 

[RayDunzl]

Impressive! Is that at the optimal airspeed Vldmax?

Around 55mph airspeed gives the best glide ratio. Expect 100 to 200fpm drop in "normal" air (it varies).

The rating for it is 36:1, which puts it in an "intermediate" category. It was competitive, but probably not a winner, when designed in the 1970's.

I like it, nonetheless. Aluminum, so you don't have to cover it or put it back in a trailer to keep it out of the sun. Has flaps, will give about 800fpm drop at 50mph if fully extended, has negative setting for extra speed and light positive setting to slow in thermals. It weighs 420 pounds.

Polar:

Blue Line:
Left is glide ratio, bottom speed
Red Line:
Sink rate (legend at right side) at speed (bottom)

Speed really increases the sink rate - you have to go downhill to speed up.

There are two phases of flight, gliding (not circling) and thermalling (circling in rising air).

When gliding you might try to speed up to get through an area of sinking air, and use the extra speed to rise back up and slow down to linger in rising air.


The fastest I go is about 80mph, and you are defitiely going downhill there. Average speed about 60mph, due to the way the trim works in my plane - has notches, not ifinitely adjustable. I don't notice speed that much, looking at clouds and usually not too concerned about covering ground.


Here's a recent "best flight", assuming you can see it. Long glides, good thermals, flew a predetermined route

SeeYou

SeeYou makes you a better pilot.

seeyou.cloud

The fastest I've gone is about 120mph, and you really have to point the nose down to do that.

I save the speed runs for the end of the day when it is time to land but still real high near the airport.


Modern glass ships are around 50:1 glide ratio.

Diana Sailplanes Diana - Wikipedia

en.wikipedia.org

The record holder is 70:1

Eta (glider) - Wikipedia

en.wikipedia.org

They will go considerably faster than I can go with the same rate of descent.

Maybe someday I'll get a slippery ship. But I'm having enough fun for now.

 

[MRC01]

It has been a long, long time since I flew a 172. Am I remembering right that the best speed for this is 60 knots? Or was it 65 knots (maybe a 152 was 60 knots)?

That's about right, around 65 kts at gross weight, 60 when light. Plus or minus, depending on the model year. One interesting aspect of glide or lift/drag ratio is that it is unaffected by weight. If you are heavier, the ratio is the same as when you're lighter, though optimal speed you need to achieve that glide is a bit faster.

BTW, my intuition proves correct about flying squirrels, their glide ratio is apparently about 2:1.

Gliding Performance of the Northern Flying Squirrel (Glaucomys Sabrinus) in Mature Mixed Forest of Eastern Canada

Abstract. There is a paucity of empirical data on gliding abilities of most gliding mammals, including flying squirrels in the genus Glaucomys. I assessed

academic.oup.com