Virgin Orbit UK Launch Live Feed

[Graeme]

Virgin Orbit UK Launch Live Feed

https://www.youtube.com/watch?v=5Co18HcyqHk

Should be interesting!

Aparently, they used a 747 because it has an attachment under the wing for carrying a spare engine that they adapted to carry the rocket.

Regards

Graeme

[ChrisGreaves]

Virgin Orbit UK Launch Live Feed

Two questions:
(1) Why are the Brits sitting on the beach mid-winter? Isn't the weather just a bit different from summertime?
(2) Who do I contact to get the drop delayed a bit? I have a scheduled telephone call from Australia at 8pm my time, i.e. they planned this to conflict with my international call.
Thanks, Chris

[RonH]

You must have found the launch contact because rocket suffered an "anomaly". The satellites it was carrying could not be released and were lost. I guess your call with with Australia proceeded normally

[ChrisGreaves]

You must have found the launch contact because rocket suffered an "anomaly". The satellites it was carrying could not be released and were lost. I guess your call with with Australia proceeded normally

Hi Ron,
I didn’t get that far.. The phone call was a disaster; it was with one of those artsy-fartsy editors who has absolutely no concept of what life is like in the real world (of logic and programming), even when I have written the thirty articles.
I couldn’t focus on the beach crowds, so went to bed and contemplated the high-level Physics of a three-stage rocket launch where the first stage is a Boeing 7xx.

The execs who pursue these schemes (Vertical Launch from Ground and Horizontal Launch from Plane) must know what they are doing. I have no doubts at all about the financial budgeting, the calculations of Energy and ROI. None at all.
But I ponder the elemental Physics. Using some basic assumptions from what I know:-

(1) Both systems launch satellites of a mass at or less than a domestic refrigerator (to an order of magnitude)

(2) The VLG uses brute force to project the payload to Low Earth Orbit whereas the HLP propels a Boeing up a ramp to an altitude of about 30,000 feet at a speed of 600 mph parallel to the earth’s surface. (An image of the peak of Mt Everest comes to mind)

(3) LEO needs a speed of about 18,000 mph at an altitude of anything from 120 to 930 miles. I shall use the lower figure because I was taught always to work in “Energy”, and I don’t want to be extravagant here

(4) Both VLG and HLP consume at least sufficient energy to give the satellite loads equivalent potential energy, should they fall to the earth’s surface.

(5) The HLP expends more energy on account of its ramp-like climb of the first stage. That climb takes about an hour (say 15 minutes to gain 5 miles of altitude and 45 minutes for final pre-launch checks). The one-hour climb consumes energy for one hour, which I suppose to greatly exceed the equivalent component’s energy required by the brute-force VLG.

(6) I had considered the rocket’s payload, but I see it looks like an engine, or a large bomb load. It appears to be about the mass of a second-stage SpaceX rocket.

(7) At “drop” time we are left with the need to propel the mass of a second-stage SpaceX rocket to 18,000 mph at 120 miles altitude.

(8) At drop time the mass of the rocket is travelling at 600 mph at 5 miles altitude. Thus after drop, the second and third stages are at 1/30th required speed and 1/24th altitude. Perhaps this is the same state as the second-stage SpaceX after the boosters have separated and begun their fall back to Earth.

(9) If so we are left with comparing only the first-stage costs (time, energy etc) of the two systems.

(10) The main difference between the two systems appears to be mobility. The VLG offers no mobility of launch. A month ago one VLG was rolled back from its loading spot back into an assembly building on account of predictions of bad weather. The HLP offers a bad weather launch ahead of the weather’s arrival AND a drop zone some 600 miles away from the take-off point.

HLP_01.png

If I’ve used Google Maps and MSPaint correctly, the drop area looks like this. FWIW I spent a few seconds watching the Boeing on Flight Radar. The Boeing appeared to be circling around my yellow blob. I suspect that only the Western half of the circle is available for drop; Nobody wants to upset Hans by exploding a malfunctioning second or third stage while he is replying to a VBA question, right?

(11) Mobility of launch site might be an advantage to time-critical launches, were one to be considering either human or other livestock passage to remote parts of the world, or schedules for meeting space stations in their orbits.

(12) BobH might be amused by the operation of his Conversions link. It converts within a system, for example "feet to miles", not just between systems.

(13) I think too, that the bulk of the Energy requirements are in the boost from 1/30th and 1/24th noted above. Specifically a 30-fold increase in speed requires a 900-fold increase in energy). See Kinetic Energy and Why Doesn't SpaceX Recover the Second Stage at around the 9m50s mark.

(14) From point (2) above "parallel to the earth’s surface" two extra bursts of energy are required; the first to begin rotating the second stage towards an angle perpendicular to the earth's immediate surface, and the second to negate the rotational momentum gained by the first burst!

(15) These two rotational components must put strain on the fabric of the stages, although I note that by this time we are well above MaxQ. Still their is the angular momentum of a fairly rigid structure to be considered.

Cheers, Chris

[RonH]

That, Chris, is such a detailed analysis from a man of few words

[ChrisGreaves]

That, Chris, is such a detailed analysis from a man of few words

It took me several hours to trim it down⁽¹⁾.
Now I have to be extra-careful not to go looking for real data and doing real calculations. Armchair, pipe, and slippers is good for me these days.

I wouldn't have called it an analysis as a "musing", My/our problem is that we are immersed in this period of development and advances. I think that you, like me, are (is? am?) old enough to remember the Sputnik launch and how, in those times it seemed obvious that the rockets had to fall into the oceans.
Today's teenagers must feel that it is normal to recover rockets.

We remember too those embarrassing failed US launches until "they got it right", so last night's "failure" was in some sense not a failure at all, but the successful consequence in taking yet another first-step along a new path.

⁽¹⁾ And to nudge Norway out of the black circle

Cheers, Chris

[RonH]

Glad you kept Norway out of the 'black'.
Cheers, Ron