On Sat, 26 Dec 2015 18:02:59 +0000, Phil W Lee
wrote:

John B. considered Fri, 25 Dec 2015 08:28:15
+0700 the perfect time to write:

rOn Thu, 24 Dec 2015 20:47:53 +0000, Phil W Lee
wrote:

John B. considered Wed, 23 Dec 2015 09:14:08
+0700 the perfect time to write:

A great deal of redundancy snipped


Well, a military aircraft should anticipate the possibility of the GPS
constellation being knocked out.

But there is no necessity. You said, above, that you could use radio
beacons and other radio stations to navigate by.

Or INS, or celestial navigation.

Are you serious? Celestial navigation? In an airplane? It probably
takes 10 to 15 minutes to actually make a minimum of two star sights
and work out a position. Which is possibly accurate to, say a 2 mile
radius. In an aircraft flying at, again say, 500 MPH (Boeing 747
cruise M-0.85)?

In 10 minutes the airplane travels ~80 miles while you are fanatically
making a series of fixes. All accurate to a location 75 miles behind
you.

But you know how fast you are flying, and in what direction, so just
making occasional fixes allows you to correct for the difference
between forecast winds aloft and actual - which is all you need.
Unless you are skirting very close to controlled or restricted
airspace, you only need to know where you are to within a couple of
miles, at least while you are at altitude and over featureless terrain
or ocean.

More snipped
But more realistically, most yachtsmen, on offshore voyages, carry at
least two GPS receivers, and sometimes even more. I've even got a
wrist watch device that includes GPS. Some boats carry "chart
plotters" and don't use paper charts at all any more.

What kind of battery life does your wrist GPS have?

A rechargeable one :-)

Which can be re-charged from either the solar panel or the wind
generator.

Either of which can be damaged or destroyed by adverse weather.
It's a bit like self-steering gear. Nice to have, but a good sailor
should know their boat well enough to be able to balance it on most
points of sailing, or if it is badly balanced, at least know which
points of sailing it will or won't hold without manual steering and
sheet management. Heck, even roller reefing (or more particularly,
the gooseneck it uses between boom and mast) is a weakness that a good
sailor should be able to manage without if necessary.


Frankly, I hear that a lot, from shore bound folks, but in reality
when you go to sea there are a lot of things that can't be repaired
without outside help. I've never seen a sailing yacht with more then
one auxiliary motor and the cry, "Oh! I'll just sail it." is not
really a solution, in some cases when the engine fails. I knew a bloke
who's transmission failed about 10 miles out from Phi-Phi Island, in
Thailand, when he was trying to get to Langkawi in Malaysia - about a
hundred miles - during the S.W. monsoon when there are very light to
no winds in that region. It took him nearly two weeks and much of the
time he was drifting with the tide and anchoring when the tide turned.
The VL cargo ships have only a single engine and propeller.

If the gooseneck breaks, depending largely on the type of rig, the
boat could probably be sailed with the main loose footed as the boom
actually only serves to make the sail easier to handle - single sheet
- and allows for more control of sail shape - out haul.

Self steering :-) ever try hand steering a boat for days and days? I
have and it is not really something that I care to repeat.

As for "balanced without manual steering", very few sloops - probably
the most common yacht - can be sailed that way. And saying "which
points of sailing it will or won't hold without manual steering" is
even worse. The N.E. Monsoon will blow for the next 5 months and I
want to, have to, go north. No sloop I've seen will sail to windward
hands off.


and yet more snipped

As for Edwards AFB, they have a lot of odds and ends of aircraft
there. Some, and I suspect the Slingsby Firefly, as there were a
couple of crashes with that aircraft, that Edwards did some flight
testing to see if the aircraft would recover from one particular
maneuver. The aircraft passed the tests I believe :-)

Yes, the aircraft didn't have a problem - the crashes were all put
down to pilot error. But I don't know why they retained that
aircraft, let alone the AN-2.

At least when I was stationed there were a lot of old aircraft
scattered around. At one time - maybe in the very late 1960's - I saw
what may have been a Hiller X-18, which flew its last flight in 1961.
And of course the B-52A (only 3 ever built) that had carried the X
aircraft :-)

All the large and medium sized aircraft are now turbine, yes.
They tend to be more expensive initially, but with much lower running
costs, so if you keep them long and do lots of hours, the total cost
of ownership is lower.


They also produce far more power from a smaller, lighter package :-)

Some of the H-34's (I think it was) were converted from Recip engines
to turbo and had a rather surprising amount of ballast added to
compensate for the reduced power plant weight.

But, you get more revs from the kick starter on a bike than the
starter on a large aircraft engine.

On large aircraft engines, maybe, but I've not had much to do with
them. I do know that motorcycle kickstarters are very variable,
partly depending on size. Big singles (500+cc) are particularly slow.

Really, I had a Harley 80 cu. inch, flat head, and had no problem kick
starting it. I never owned a 500 c.c. bike but I did ride a mate's 500
c.c Norton single and it started easily. (In fact, the first
motorcycle I saw with an electric starter, I wondered about whether it
was intended for the ladies :-)

Did your Harley have magneto ignition?

Nope, but your remark about the "big" 500 cc bikes I assumed that you
were referring to engine size.

It's more individual cylinder size, as that's what you are compressing
in one go in order to start it. And of course, if it's not magneto
ignition, the minimum speed at which a magneto will give a spark is
irrelevant, as you have a battery to do that.

Well, the 500cc single engine has a 30.5 cubic inch cylinder while the
80 cubic inch Harley twin had a 40 cubic inch cylinder, and, to the
best of my knowledge the Harley "80" was made only with a manual kick
starter :-)



The Norton's (and similar BSAs, Matchless, etc) difficulty in starting
was almost directly determined by the state of tune - the higher the
power it was tuned for, the more difficult it was to start.
But the point (pardon the pun) is how fast the engine needs to spin to
give a useful spark. I'll bet that it was too slow to even register
on the rev counter until the thing was running. It has been on every
four stroke I've ever owned with a kickstarter.

I never owned a "big Bike" that had a "rev counter"

Yes, likely due to advanced Ignition timing. I once helped to push
start a Norton 500 cc "feather bed" racing bike at the Daytona Beach
races that the rider said was impossible to kick start.

It's only partly ignition timing - compression ratio and valve timing
are also significant factors. Pure racing machines often did away
with the kickstarter altogether, because it was both useless and added
extra weight.
But you can get a spark from magneto ignition down to about 100rpm -
so if you can make the kickstarter turn it, you can usually start it.
If it cranks much below that, then yes, you probably need an impulse
coupling, so aircraft which are hand started by swinging the prop, or
large piston engines pretty much need them. But even on those, the
ignition system is self-contained, and has no connection to any
external power or even the battery.

To drag this slightly close to being on topic (warning - thread
collision possibility), bicycle generators are technically (low
tension) magnetos, as they don't have field coils but permanent
magnets.

Come now. I flew with my father when I was just a lad, in a Piper J-3
and it didn't have any vacuum instruments in it.

Only because it only had pitot/static instruments and a turn & slip
indicator!

No turn and slip indicator. An altimeter, magnetic compass and air
speed was all the flight instruments it had.

Yeah, I knew they didn't have a lot.
The continued existence of aircraft like that is one reason why it's
still legal to operate NORDO (outside controlled airspace) - because
you can't fit a radio to something without an electrical system.
Of course, the same is true of some yachts, and the conditions under
which they can operate is potentially far more hostile to electrical
systems, both in severity and duration.

The preferred navigation method was to follow the railroads :-)

That only works in VFR below the clouds.

Piper Cubs were only flown VFR!!!!


By the way, there is a research paper titled "Vision-Based
Road-Following Using a Small Autonomous Aircraft" done at the AINS
Center for Collaborative Control of Unmanned Vehicles, University of
California, Berkeley, which apparently is dated 2003, which describes
the method :-)

There's also a whole set of RFCs on the carriage of datagrams by avian
carrier, with and without quality of service and even encryption -
bandwidth is quite high, but latency issues make it unsuitable for
most applications
But while such things are amusing, there are actually some genuine
rules for following what are termed "line features" in aircraft
navigation, mostly to avoid meeting another aircraft following the
same feature in the opposite direction. This can result in a rather
bad landing for both aircraft (a good landing being one you can walk
away from, and a great landing being one where the aircraft is
reusable). In a nutshell, you keep the line feature on your left
(giving horizontal separation), and choose your height according to
your magnetic track (giving vertical separation) - meaning you need to
get at least two things wrong before there is any danger. Well, three
really, since looking where you are going is also highly recommended

--
cheers,

John B.