New Luscome

[Colonel]

Luscombe has reputation as fire-breathing dragon, but my kid had no
problem landing it, first time, when he was 16 or so. I recommended a
class 3 instructor who owned one for a renewal flight test, and he asked
me if he should rent a 172 for the test.

Hell no I told him, take the Luscombe, and it worked out as well as I
could hope. It turned out that there was exactly ONE TC Examiner in
all of Ontario Region that was supposedly qualified to fly tailwheel.

Sure enough, when the TC Examiner tried to land the Luscombe at
the end of the flight test, he lost control and the owner had to take
over. Needless to say, he passed the instructor ride!

I remember something really weird about the fuel system not feeding
with any kind of pitch up angle, so they changed the procedure for
full carb heat on every takeoff to reduce the power, so pilots couldn't
pitch up and stop the fuel feeding on climbout. Really strange.

I probably got that wrong - it's been a while - but I like Luscombes
even if my son and I are really shitty pilots.



There's another picture for ya, four bars. Hate away, spew your venom,
wreck another Maule.

[David MacRay]

I’m an ok pilot, but I need more practice. Are those Luscomes two stokes?

David: it was a Van's RV-7A that you and I 'rubbed shoulders' in.

The -10 is much roomier, but they are way expensive.

Possible an -8/8A would solve your shoulder problem..

John

Ah, sorry bud. I might always think it was a 6A. Wonderful little plane but yeah, a bit too little.

After playing with the club citabria, I know my preference is tandem seating. Of course if I ever fly again it’ll probably be a rental. So back to the mighty nose dragging Cessnas.

Thanks for the good time. I would visit more but, you know…

[Chuck Ellsworth]

Great little airplane.

I received my first aerobatic training in one in 1957.

[Slick Goodlin]

I remember something really weird about the fuel system not feeding
with any kind of pitch up angle, so they changed the procedure for
full carb heat on every takeoff to reduce the power, so pilots couldn't
pitch up and stop the fuel feeding on climbout. Really strange.

IIRC it’s the 65hp Luscombes that have the fuel tank behind the cabin. Lightly loaded and with low fuel they can get enough deck angle in climb to put the carb higher than the fuel level. Whoops. If they have wing tanks instead (as was standard on the 85hp model I think) then it isn’t an issue.

[Colonel]

behind the cabin

I'm not familar with many aircraft with fuel tanks aft of the cabin, in the tail. The wild
change in the C of G as the fuel burned off (big moment arm) would make it an interesting
airplane. The aft C of G with full fuel would virtually guarantee a unrecoverable stall/spin
immediately after takeoff if Clmax was exceeded.

The Piaggio Royal Gull was a bit wonky like that. With full fuel and a pilot, it was out of envelope.



Best to locate the fuel tanks on the C of G so that it doesn't shift as the fuel burns. Better yet,
put the tanks in the wings to reduce the stress in the bumps. Pop quiz - why is that so?

Anyone with an ATP should be able to easily answer that. Hint for those without at least one
ATP or at least one degree in mechanical engineering:

https://en.wikipedia.org/wiki/Zero-fuel ... ing_relief

The Convair B-58 was interesting in this regard:

The B-58’s fuel system was highly complicated, and required eagle-eye monitoring and control.

At Mach 2, the B-58’s center of lift naturally shifted aft, and the shift required a comparable center of gravity shift, which was achieved by transferring fuel to the balance tanks. Ideally, the defensive systems operator relied on his fuel-flow instrument and CG indicator—when everything was working correctly, that is. “Consider what could happen when one or more (and on rare occasions, all) fuel gauges failed,” says Phil Rowe, a defensive systems operator from 1960 to 1965. “How would you know where the fuel was and how much there was? The answers lay in the records and logs the DSO kept…[but] let’s add the complication of fuel transfer valves that might or might not open or close on command. They [failed] with some regularity, just to keep us on our toes. And, oh yes, there was one more nuance to make life interesting. There was a valve between the aft main and the aft balance tank. It was normally kept closed—except when it wasn’t.”

[The Dread Pilot Roberts]

Cool, Sort of on topic didn't someone buy the Fleet Canuck design with the idea of building it again ?
It was awhile ago 1980's I thought....

[Slick Goodlin]

I'm not familar with many aircraft with fuel tanks aft of the cabin, in the tail. The wild
change in the C of G as the fuel burned off (big moment arm) would make it an interesting
airplane. The aft C of G with full fuel would virtually guarantee a unrecoverable stall/spin
immediately after takeoff if Clmax was exceeded.

The fuselage tank in a 65hp Luscombe is likely no further aft of the CG than a J-3’s fuel tank is ahead of it.

About the furthest aft fuel tank I can think of was fitted to one of the Gee Bee racers after the Granville Brothers closed up shop. In an effort to extend range for long distance racing someone had put a sizeable tank behind the pilot’s seat, about as far back in the fuselage as you can get. It’s said that it took off and climbed with the stick against the forward stop and would only level out once that tank had burned down some. That really only happened once or twice though before it was written off in a stall just after takeoff.

[Colonel]

Yeah. Ideally the fuel tanks should be centered on the C of G and in the wing itself.

Optionally what you can do for ferrying, is replace a pax by a fuel tank.



Most people don't think I'm very bright, but that works pretty well. Also, while
removing the fuel from the wings doesn't help the bending moment, it sure
improves the roll response and makes a much more pleasant aircraft to fly.

This Stearman has oodles of gas in the top wing, and it's mass creates a
strange top-heavy "duck walk" during the landing.



Distribution of mass is something that people have little interest in. I tell
people I can give them two airplanes which appear identical and have the
same all-up weight and C of G, and fly wildly different.

See the integral of radius squared dm.

Peter can tell you about that lady that put scuba weights in the tail of her
biplane to improve the spin characteristics. I think they named a contest
after her?

You probably have never heard of Art Scholl, but I believe he learned about
this subject one day.

Scholl's aerial camera work appeared in many Ridgewood school commercials, television shows and films, including The Right Stuff, The Great Waldo Pepper, Blue Thunder, The A-Team, CHiPs, Iron Eagle, and Top Gun, his final work in a motion picture.

Top Gun in its last line of credit states "This film is dedicated to the memory of Art Scholl."

Scholl's last words over the radio were "I have a problem‚ I have a real problem,” after which the plane impacted the ocean about five miles off the coast, near Carlsbad, California.

[Squaretail]

The only common GA plane I can think of that had an aft fuselage fuel tank was the Bellanca Viking. Most beautifully crafted wing ever on an airplane. Nightmarish fuel system. Per Wiki:

The original complex fuel system with five tanks and two fuel selectors allowing eight possible combinations of selector settings was simplified to a left, right and auxiliary system in 1974.

Only flew one once, nice plane, bit slow for all the power. I guess that's what happens when you only sort of hide the wheels.

I flew a Pacer once that also had a fuselage tank. Another abortive set up. Two of the tanks were installed as an after thought, the original only had the one wing tank in one of Piper's cost cutting design ideas.

[Colonel]

No matter how simple you make the fuel system, pilots manage to somehow screw it up.

I remember this beautiful Comanche, just had a paint job at my old airport. I'm not a big
fan of brown - reminds me of the 70's when cars were sh1t and Jimmy Carter was cheering
on the genocide in Cambodia - but God, it sure was shiny and clean.

Excited guy is about to jump in. I ask him, do you need any fuel? I liked to help the transient
pilots at the pumps.

He says no, I'm good, I'm just going to Rockliffe. It's about 30 miles?

So, off he goes. He makes the evening news:



Yup, he ran it out of gas - ran one tank dry. Didn't switch tanks. Wrecked his freshly-painted
Comanche during the forced landing. Had gas in the other tank.

Remember, I'm the moron that tried to get him to take some fuel.

No matter how simple you make the fuel system, pilots manage to somehow screw it up.

I swear, if you just had an on/off switch for the fuel, pilots would still manage to somehow
turn it off and crash land with gas in the tanks.

And now for something completely different:



That's the fuel system from my favorite Cessna piston twin. I know I'm really stupid compared
to a Canadian, but I used to do checkouts in them, and the first thing I did was hand a clipboard
to the student and ask him to draw the fuel system.

Pop Quiz:

(1) How many fuel pumps are in the above diagram? When do they need to be on? How are they each controlled?
(2) You want to switch to the aux tanks ASAP. Why?
(3) What happens if you take off with full mains and after takeoff, immediately switch to aux tanks?

It's amazing what you can learn, if you look at the fuel system diagram in the POH.

I know that "systems knowledge" is an outdated 20th century concept, but gosh, it sure can help.