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Biplane Outside Loop Difficulties

Posted: Sun Dec 20, 2020 1:26 am
by JW Scud
"“In 2014, I received a letter from the original builder, Charles Lamb,” Eric said. “He
said he had recently awakened from a deep
sleep with an epiphany as to why Vern
hadn’t been able to make the airplane do an
outside loop. He said that he remembered
that he had set the top wing to a four-degree
negative angle, rather than the usual slightly
positive angle. I measured it, and he was
right. So, I changed the angle. Whether it
will do an outside loop now, I don’t know,
and am in no hurry to try to find out.”

Any advice on biplane wing angles. I found that statement interesting.

Re: Biplane Outside Loop Difficulties

Posted: Sun Dec 20, 2020 5:29 am
by Colonel
Curtis Pitts is dead now, but I remember hearing that he struggled for
quite a while with the "round wing" Pitts. The original Pitts used a flat
bottom wing, but for better lift with negative AOA, Curtis went to the
"round" or symmetrical wings. They are very different, top and bottom
(camber) and I have no idea about the incidence.

The Steen Aero guys probably know more about this.

All I really know for sure, is that it does great pushes. I've done
hundreds (thousands ?) of them.

Dear Old Dad and I use to do an inside-outside loop. What I learned from
doing them for many years is that although the wing was symmetrical, the
airplane was not.

Under negative AOA I think the landing gear spoiled lift, and it would stall
faster than under positive AOA. This is yet another reason to have the lead
fly the outside loop - the wing, with positive AOA, has more margin of AOA
and that is a good thing.

That's why you never turn into a formation. Well, I do it all the time, but
classically, it considered poor form. Wing is now at a higher AOA than
the lead. Not good. When I turn into a formation, I want them tucked in
as tight as possible (why?) and I hammer the throttle (why?)

Hey John, flying as wing in right echelon in four-plane in Sabres, did the
lead turn into you very often, steeply or at low altitude? If not, why not?

Flying wing at low altitude, I stalled once at low altitude when the (civilian)
lead turned into me. I'm still alive, but it's because I'm not a very good stick.

Moral Of The Story: Never fly wing on someone who isn't a better pilot
than you are. This group may be very small. This is ok.

Re: Biplane Outside Loop Difficulties

Posted: Mon Dec 21, 2020 5:38 pm
by Colonel
Update on biplane wing incidence:

A friend of mine - he's dead now, of course - had an S-2C and wore it out.

Even with the magneto drive disconnected most of the time - everyone does
that, right? - he had the highest time S-2C in the world.

So he bought another S-C and sent the worn out S-2C to another friend of
mine - he dead now too, of course - for a rebuild.

It looked fantastic after the rebuild. Flew hands off, which for some really
weird reason is important to people, like greaser landings. Fucking weird,
must be some four bar shit that I don't understand.

Anyways, the first S-2C, after it was rebuilt and flew hands off, was 15 knots
slower
than the second S-2C direct from Aviat. They looked the same,
engines the same, prop the same, but after new fabric, MUCH slower.

I think at least one wing had WAY too much incidence and hence AOA and hence
drag in cruise, but Canadians tell me I'm not very bright. Too many washers
at the back of the I-strut.

Re: Biplane Outside Loop Difficulties

Posted: Mon Dec 21, 2020 8:33 pm
by John Swallow
Andrew:

About the only time we flew in four-plane echelon - even now with our Vernon Snowflakes - was during the run in to the pitch. It was/is considered poor form to turn into the formation.

In days gone by - probably around your father's time over in Europe - there was a story about a CF-100 lead who broke INTO the formation on the pitch. Good reflexes by the other three pilots prevented parts raining on the airport...

With two plane formation (or box), into/away from the winger is immaterial, but as you say, if you're maneuvering at relatively low speed, the lead has to be cognizant of problems faced by guy staring at the sky...

(Edit) Afterthought: the problems/limitations of being distanced from the lead in formation is brought home while executing a line abreast roll; the most we could do consistently was with five airplanes. On initial roll after the pull up, the guy on the outside of the roll had the throttle through the firewall while the guy on the inside was using speed brakes. On the recovery, it was the reverse... All this at airshow altitudes.

Re: Biplane Outside Loop Difficulties

Posted: Tue Dec 22, 2020 5:43 am
by Colonel
Image

You could probably roll that. I would come in, descending with a lot of speed and
a fairly low power setting (as lead) then pitch up and roll LEFT.

Number four would be covering a greater distance and would need more percent,
but I think it would be do-able. The trick as lead would be to pick your speed so
that four stays just sub-sonic.

Once you get that sorted out, put another three guys in left echelon. You would
be rolling towards them, so they would need to slow down. Lead would need to
keep fast enough (see comment above) to not stall number seven on the left.

But that would be a seven plane roll in vic :^)