Showing posts with label July. Show all posts
Showing posts with label July. Show all posts

Monday, 6 October 2025

The Banishing of Huginn

The Banishing of Huginn

I'm blessed by having many wild birds around my house. There are all sorts of birds, and as I live here longer, I am getting better at identifying the different species. There are wrens, wagtails, great tits and brave little robins; pigeons, blackbirds and magpies in various numbers from ominous one, through joy to silver, gold and dark secrets. And then there are the corvids: hooded crows, like capuchin monks and rooks, loads and loads of rooks. I lump them together as "crows". The rooks roost in the oaks and return home for sunset, squabbling as they settle for the night. 

My wife was in the habit of feeding the birds in the early evening. She would scatter seed and shattered fat-balls on the back lawn. You can't feed the smaller birds without feeding the crows, who are fiercely intelligent. A sentinel or two would be stationed on the ridge of the garage roof and within seconds of food being scattered on the ground, the sky would darken and the ground covered with raucous family groups: this year's spoiled fledglings demanding to be fed by over-tolerant parents scarcely larger than themselves.

One afternoon in early autumn, I was standing at the back door observing the crows. Many were picking away at the lawn, looking for seeds or scraps they had missed earlier. A few were strutting about, proudly grasping an acorn in their beak. When they found what seemed to them a suitable spot, they would put the nut down carefully, peck a hole, place the acorn in the hole and cover it up. They would then turn away, apparently satisfied with their work. I can't see the point myself, but I understand how oaks are planted.

I had some minor tasks to do, so I went outside and before I started I paused for a moment and surveyed the crows. They have grown used to me and after a brief fluttering of wings they settled back to their business of gleaning.

Suddenly, a single rook separated from the group and flew straight towards me. I stood my ground. I don't claim bravery, rather the slow responses of advancing years. The bird turned upwards, its wings spread and its feet extended towards me. It alighted on my right shoulder. I felt its weight shift as it adjusted its position and I turned towards it. I found myself face to face (or maybe nose to beak) with the bird. It seemed to be a juvenile, with a black beak, rather than the boney grey of an adult. As it turned its head from side to side I was looking into its eyes. I was entranced, frozen as if in the presence of great power. The bird was not hostile, instead it projected calm, but uncaring interest, a remote intelligence observing and noting my actions. Unbidden, I extended my right arm, until it was horizontal, my hand clenched in a loose fist. The bird walked calmly along my arm until it was perched on my hand. Its feet were scaly and cool. I put my left hand, palm upwards, in front of it and it reached across and gently gripped my fingers and the skin of my palm. This was not an aggressive act, not a peck, just a gentle caress and I could feel the serrations of his beak.

For the rest of the day, and the whole of the following day, I had a new companion. I decided "he" was a boy (though I cannot tell the difference, and it matters only to other rooks) and named him Huginn. He would come to me when I was outside, perch on my shoulder and fist and eat from my left hand. He took cat food from a small saucer I held in my hand and even half a hard-boiled egg directly from my palm.

On the third day he was gone: no more Huginn. There was no sign of him. He had disappeared without leaving a trace except in my memory, returned to the emptiness from whence he came. I missed him as one would expect to miss such a companion. I still miss him and mark his absence. Stories of talking birds and magical familiars now seem much more real and much more likely than they once did. Experience is a powerful tutor. 

The worldly explanation is that Huginn was probably a chick from the previous year. He had "imprinted" on one of the women who work at the garden centre which is associated with the COPE (Roughly the Irish equivalent of SCOPE) across the road. As he had become more confident he had begun venturing further afield and had found me. The reason he had disappeared was that unfortunately he had begun to become a nuisance at the Garden Centre, disturbing customers and the residents at the COPE home. As a consequence he had been tempted into a cage and then "re-homed" some distance away. We all hope that he is happy and will eventually find a mate.

Of course, there could be another explanation, one which if I'm honest, I rather prefer. In Norse and Germanic mythology Odin, the chief of the gods, who traded one eye for wisdom, was served by two ravens known as Huginn and Muninn (memory and thought) who brought him news of all they had seen in the world. There seems to have been uncertainty or dispute about whether Huginn and Muninn were simply messengers or whether they were extensions of Odin himself. Whichever they were, I like to imagine that I had an encounter with the numinous, the divine, and that Huginn has returned to Odin with the message that I had been set a test (which I do not fully understand) and that my response had been satisfactory. 

(I originally called this "The Murder and the Banishing of Huginn", to use the collective noun for a group of crows. When I read it, I thought it was a piece of unworthy click-bait!)

[Original Events: 13th and 14th July 2025]

[Date: 6th October 2025]                

Monday, 6 February 2023

Flying not Floating

 

Flying not Floating

The simplest formula for calculating lift that I can find is:

 ρ v2 S CL

Where:

·         L is the lift force

·         ρ is the fluid density – originally of “air”

·         v is the velocity or “true airspeed”

·         S is the planform (projected) wing area

·         CL is the lift coefficient at the desired angle of attack, Mach Number and Reynolds Number

https://en.wikipedia.org/wiki/Lift_(force)

(The representation of the equation got mangled and I can't be bothered to fix it)

Typical value of CL lift coefficient is 1.5

https://www.sciencedirect.com/topics/engineering/lift-coefficient

If I assume that I want Lift force equal to the downward force, then that means the Lift I require is (Mass * local Gravity).

Do some algebra and rearrange the equation to get (looks like super and sub-scripts don’t work properly in equations with fractions):

The first term is a constant for the body in question, the second term is the inverse of the density and the third term is the inverse square of the “airspeed” velocity. Everything varies as you would expect.

Physical Properties on various bodies:

Body:

Gravity (m/s2)

Atm Density (kg/m3):

Lift for 1 kg (N):

Temp (deg C):

Atm Pressure (Bar):

Notes:

Venus

8.87

65

8.87

464

92

 

Earth (Air)

9.81

1.2

9.81

20

1

*

Earth (Water)

9.81

1000

9.81

20

1

*

Mars

3.72

0.020

3.72

-63

0.06

 

Jupiter

24.8

1.2

24.8

-70

10

*

Saturn

10.44

1.2

10.44

-139

1

*

Titan

1.35

53

1.35

-179

1.5

 

 

Notes:

(*)          Atmospheric density on a gas giant can be anything you choose it to be, depending on altitude/depth.

Calculate the “factor” for all the different bodies

Body:

L/CL:

Inverse Density:

“Factor”:

Venus

5.91

0.154

0.910

Earth (Air)

6.54

0.83

 

Earth (Water)

6.54

0.001

 

Mars

2.48

50

 

Jupiter

16.53

0.83

 

Saturn

6.96

0.83

 

Titan

0.90

0.94

 

 

 (Originally 17th July 2021)