Relatively rare airplanes.

[Jamesel]

Thanks Barney.
I've always been intrigued by the "Hummingbird" and the dH-71 "Tiger Moth".

[Chuck Ellsworth]

Anyone here remember the good old days when we flew piston pounder's that had BMEP gauges for setting power?

[Colonel]

I find BMEP fascinating:

[quote]Brake Mean Effective Pressure (BMEP) is another very effective yardstick for comparing the performance of an engine of a given type to another of the same type, and for evaluating the reasonableness of performance claims or requirements.

The definition of BMEP is: the average (mean) pressure which, IF imposed on the pistons uniformly from the top to the bottom of each power stroke, would produce the measured (brake) power output.

Please note that BMEP is purely theoretical and has NOTHING to do with ACTUAL CYLINDER PRESSURES. It is simply a tool to evaluate the efficiency of a given engine at producing torque from a given displacement.

A torque output of 1.0 lb-ft per cubic inch of displacement in a 4-stroke engine equals a BMEP of [u]150.8 psi[/u]. In a 2-stroke engine, that same 1.0 lb-ft of torque per cubic inch is a BMEP of 75.4 psi.

This tool is extremely handy to evaluate the performance which is claimed for any particular engine. For example, the "angle-valve" Lycoming IO-360 (200 HP, 360 CID) and IO-540 (300 HP, 540 CID) engines make their rated power at 2700 RPM. At that RPM (2700), the rated power requires 389 lb-ft (200 HP) and 584 lb-ft (300 HP) of torque respectively.

From those torque values, it is easy to see that both engines operate at a BMEP of about [u]163 PSI[/u] (11.25 bar, or a "torque ratio" of 1.08 lb-ft per cubic inch) at peak power. The BMEP at peak torque is slightly greater.

For a long-life (in an aircraft frame of reference), naturally-aspirated, SI (spark ignition) gasoline-fueled, two-valve-per-cylinder, pushrod engine, a BMEP over [u]204 PSI[/u] (14 bar, torque ratio of 1.35) is quite difficult to achieve and requires a serious development program and very specialized components.

At the end of the 2006 season, most of the F1 engines ran up to 20,000 RPM in race trim, and made in the vicinity of 750 HP. One engine for which I have the figures made a peak power value of 755 BHP at an astonishing 19,250 RPM. At a peak power of 755 HP, the torque is 206 lb-ft and peak-power BMEP would be [u]212 psi[/u]. (14.63 bar). Peak torque of 214 lb-ft occurred at 17,000 RPM for a BMEP of [u]220 psi[/u] (15.18 bar). There can be no argument that 212 psi at 19,250 RPM is truly amazing.

At the end of the 2014 season, the engines from one major NASCAR engine manufacturer were producing in the neighborhood of 880 HP at about 9000 RPM, and they operate at a max race rpm in the vicinity of 9400 rpm.

Consider the fact that, to produce 880 HP at 9000 RPM, requires 513 lb-ft of torque, for a peak-power BMEP of nearly [u]216 PSI[/u] (14.92 bar, torque ratio of 1.43). Peak torque for that same engine was typically about 535 lb-ft at 7800 RPM, for a peak BMEP of over [u]226 psi [/u](15.6 bar, torque ratio of 1.50).[/quote]

[Chuck Ellsworth]

The only airplane I ever flew that had BMEP gauges Colonel was the DC6 and it was a dream to fly , you would get such a hard on flying it you would go blind.

However we have to remember that today's pilots look at those machines as old technology and thus below their dignity to fly.

[Colonel]

I would give your left testicle for a DC-6 type rating  :D

Had a great flight today, Chuck ... waiting for the fuel truck:

[img width=500 height=375][/img]

I used the (short) runway 7R.  There was a T-6 making a
hell of a racket on 7L (long runway).

[img width=500 height=402][/img]

I know I'm not in much of a position to complain about airplane
noise - ever - but jeez they make a heluva noise when they go by.

Not the R-1340 of course - it's the prop tips.

Always pays not to be the noisiest airplane at the airport, I say.

PS  Did my full stop on 7R and got off at Quebec, which is a 1300
foot rollout with a 120 mph approach speed  :))

[Chuck Ellsworth]

Did you ever see that Stearman  called Samson with the 600 HP Prat radial in it Colonel.

That fucker was pure noise, it used to be in the airshow circuit.

[Chuck Ellsworth]

[quote]
PS  Did my full stop on 7R and got off at Quebec, which is a 1300
foot rollout with a 120 mph approach speed  :))[/quote]


Did you wheel it on?

[Colonel]

I would have wheeled it on, if I wanted to run a long way
down to the end of the runway - perfect for a 4000-5000
foot runway.

What works really well is a decreasing airspeed approach -
with the power off and a whole lot of bank in a sideslip on
a descending-U final, I kill the airspeed just before crossing
the runway threshold to 100 mph.

Tower is really cool, especially since they aren't getting paid
any more - they are NOT a contract tower. They call early turns
for me to fly inside the other traffic, for closed pattern, which is
nice.  They are used to strange airplanes (Pitts, Extra, Waco,
T-6 etc) which is really important to me and my friends.

Coming back to the airport, Tower likes me to fly no less than
a  5 mile straight-in final, which I start at 180 mph, then step
down to 160 mph then 140 mph then 120 mph on short final
then 100 mph at touchdown.

Busy little airport, with the parallel runways.  Sometimes different
freqs for each runway, when it gets hectic.

I know decreasing airspeed finals aren't dogma but geez, they
work well.  At least for me.  I see no reason to drag it in at 100
mph with the nose 'way up in the sky.  That's dangerous - you
can't see anything forward!

So-called stablized approaches are good for weak sticks, I guess -
easier and safer to fly if you don't have much skill or experience.

I remember flying a 172 into Pearson.  The flight training experts
would have you fly the entire approach at 70 mph, which is going
to make you about as popular as a hooker in church.  A better
approach is to fly it flaps up with all the knobs pushed in, and kill
the airspeed just before touchdown.  Or not, if you want to turn
off 'way down the runway.

[Chuck Ellsworth]

[quote]What works really well is a decreasing airspeed approach -
with the power off and a whole lot of bank in a sideslip on
a descending-U final, I kill the airspeed just before crossing
the runway threshold to 100 mph.[/quote]

The real beauty of using that kind of approach is it makes it easier to judge the closing rate and thus easier to judge the proper descent angle and for sure there is no problem with floating down the runway....

...it has been quite a few years since I flew a Pitts and there are none in this area as far as I know.

The registration of the Pitts I flew was PH-PEP.

[Colonel]

It's a weird little airplane.  Basically a Lycoming with a pair of handlebars.

Benefits enormously from a composite 3-blade prop.