That's what triggered me to post this

Indeed parachutes should be made in Orange/White "Search & Rescue" color scheme otherwise these are untraceable.
Then again when these are tested, engineers are on the spot and don't have to search for it
Take a look at this test, the parachute is well camouflaged:

I give up; what (and where) on earth is it?

It's the Orion parachute test. The parachute failed. I don't know where it is though.

It's not California, maybe Arizona or New Mexico by the look of the soil.

That mountain range looks awfully familiar...Indian Springs, Nevada area (NW of Vegas)?

Yuma Proving Grounds in Arizona on July 31, 2008.

Indeed Yuma Proving Grounds in Arizona near the Mexican border in the Sonora desert.
The Orion capsule (6500 Kg) parachute system uses two drogue chutes to stabilize the craft, then these two are cut away in order to deploy three pilot chutes, which each pull out one of the three main 35-meter diameter parachutes that are meant to ensure a safe landing speed. In compariosn, the Russian Soyuz (2800 Kg) only uses a single 35.5-meter white/orange main chute.
What was the size of Beagle 2 chute?

Not orange !!!mars is red/orange. Indigo green is what you need with white circles.......er not frost pockets......

Beagle 2's main 28 panelled parachute had a diameter of 10 meters and had 11.4 meters rigging lines with a 30 meter strop underneath.
Initially a disc-gap design was choosen, with a triconal canopy as alternative. Due to the gas-bags speed restriction of 60 Km/Hr (kinetic energy) a ring-sail type of parachute was choosen...
( Source: The Guide to Beagle 2 - CT Pillinger Section 2 The Probe )

Here is an image of the Main Parachute material

Click to view attachment

Stuart H

That really is rather transparent isn't it. Does it have much of a reflective kick to it, a shine of any sort?

Well, that explains it. They clearly used lace curtain material from an indoor market for the parachutes...

Wow. I'd characterize that as gossamer! Bet it was very, very light & of course strong, but I almost have to wonder how permeable it was and how that affected deceleration in the lower speed regime.

Looks a lot like spinnaker ripstop to me, Nick. Maybe it will win the next America's Cup?

That is exactly correct.

But it passed every test we could do on Earth. However the big unknown is how it performed on Mars.


Stuart H

Doug,

No it is rather dull on both sides. I have a sample of it at home. If we ever get to meet I'll bring it with me.

Stuart H

What grade is it? Bainbridge Force 9?
That only comes in 'natural' color.
Next time dye it as a big Union Jack!

You mean Beaufort? Someone's got pirates on the mind.

Bainbridge is the Force 9 ripstop nylon manufacturer. Their 'heavy seas' weight. (and maybe hypersonic?)
I'm strictly a Dodgers fan.

It does look so thin and pourous how much was it able to slow the craft?

Spinnaker ripstop nylon has a coating which renders it non-porous.
At least, at sailing yacht windspeeds.

The Beagle 2 book I have is out in the Shed, so I'll double check tomorrow - BUT - ballpark figures...

The parachute, at 10m across, and the lander, at something more like 60kg, combine to give a MUCH lower terminal velocity than MER. More like 40-50mph, than the 150+ that MER would have had without RAD's.

I'll pull out proper numbers tomorrow.

A parachute has porosity on a macro-scale (e.g. in a ribbon parachute, or
the gap in a disk-gap-band chute) and on the microscale (the permeability of the
fabric itself). Both are important in inflation, drag and stability performance :
zero porosity is typically rather bad.

Note that at the low Reynolds numbers characteristic of Mars flight, what looks
like a porous fabric does not, in fact, behave as such since the viscous nature of
the flow reduces the effective permeability.

Very cogent explanation, Ralph, thanks! I thought something like that might have been at work.

Somebody on UMSF once described parachute design as a "black art"; I believe it. This is just one more in a long list of often very subtle interdependent variables.

LATE EDIT: This also probably explains why Mars parachutes aren't made in eye-searing high-contrast neon colors for easy orbital identification. Since fabric porosity affects performance, introducing fancy colors by whatever means would doubtless complicate control of that parameter. Never add complexities when they aren't truly needed.

Would you care to elaborate on your concerns?
Stuart H says the material was tested on earth. Can we assume that means appropriate wind-tunnel or drop tests?

I wish I could just copy and paste the whole section out of 'The Guide to Beagle 2' - I'll paraphrase the parachute section...

The design was changed after establishing that the airbags would have to be going at less than 60kph. So they shifted to this 10m diameter ring-sail. The finished 'chute had 9 rings of 28 panels making 252 in total. The sails are sewn together in the vertical direction, but only at the corners to the next rows.

Tests seemed to include drop tests in Nevada, drop tests from a Hot Air Balloon near Oswestry, England, A pulley-fed extraction test, and a lorry-pulled test at one of the old airship hangers in Bedfordshire.

Tests predicted the terminal velocity with a lander of 57kg would be 16m/sec (35.8 mph)

Direct quote

"The material which was originally intended for spinnakers, used by racing yachts, is nylon, uncoated by any plasticiser. Instead has been calendared (rolled) to flatten the fibres thus reducing porosity. The fabric weights only 22.8g/m^2"

Like it would get ripped to shreds depending on the drag at some density and deployment velocity and strength of material.

The ribbon parachutes used to decelerate nuclear bombs from supersonic speeds appear to be very porous.

This is unquestionably a fascinating case history of engineering trade-offs - and in something as prosaic as a parachute!
(Though, presumably, we could just about choose a spacecraft system at random, and construct a similar saga.)
- COST vs Effectiveness vs Risk of Failure.
- Commercial Off-The-Shelf (COTS) technology vs Specialized Parachute Black Magic (SPBM).
- COTS costs less than SPBM, (OK?), but:
-- How like a yacht spinnaker is a Mars re-entry parachute?
-- How does the non-permeable coating of spinnaker ripstop nylon (SRN) hamper its function in a parachute?
-- How does SRN without its coating improve function, and what is the effect on its strength and durability?
-- How does flattening the uncoated SRN improve its porosity and function, and what is the effect on its strength?

No doubt the list of ponderables could be continued, with reference to weight, bulk, construction, and, yes, even color etc.
It's a game only the Anointed can play with gusto.

Zero-porosity means all the air entering the parachute has to leave again at the edge. It is difficult to impossible to get this to happen uniformly, and non-uniform edge venting leads to the parachute swinging from side to side.

Essentially a macro-scale equivalent to the vent hole in the top of the MER design?

Disk-gap chutes make LOTS of sense now, thanks, Gwiz! Venting's gotta happen no matter how porous the material is, so better to let most of it exit parallel to the center of mass & opposite local vertical (at low speeds) or parallel & opposite to the angle of attack (at high speeds) to minimize undesirable & uncontrollable lateral venting.

A vent-hole at the top is a solution to the edge-venting problem that goes back a couple of centuries.

Every time I see a new post in this thread, I hope someone is going to say "Is this dark spot in HiRISE image ---- the Beagle 2 impact site?" Is anyone looking?

Phil

Mark Sims told me that about half the ellipse has been covered by HiRISE - and that people are looking.

I'm still looking almost daily, made more or less a routine of it every time I've got a bit of spare time and nothing much on hand, one day Beagle, one day MPL, and one day Mars 3 or Mars 6, centimeter by centimeter though those images.

Point is, it's not like you don't find anything, there's lots and lots of "suspicious stones" over there, the harder you look the more you find, but it's useless to start screaming 'hurah' every time you find something weird. The 'aha' moment is finding signs of a parachute, if you don't find a parachute you've got nothing, and I'm starting to get fairly confident that as far as Beagle, Mars 3 and Mars 6 are concerned there is no clearly visible parachute in the area's covered (and Mars 3 and Mars 6 are almost useless anyway, just a fools hope ;-) ). As far as MPL is concerned, that area is just terrible, you could hide a hundred white parachutes over there.

Kind of like the proverbial polar bear in a blizzard I presume?


-- Pertinax

OT, but speaking of MPL, are any newer images available yet? If not, do we have a ballpark idea on when to expect them?

Actually - the season will be starting now. Phoenix landing site just hit 24hr dark, thus Polar Lander will be in 24hr Sun

Believe me I have been looking for the the last 5 years.

Expect an announcement fairly soon (weeks I hope) !

Stuart H

PS. re Parachute material, we were concerned about Planetary Protection ie protecting Martian bugs from being infected/killed by our coatings, so did not use any. (mistake in hindsight )
See Beagle 2 Lessons Learned no. 1673 (-ish)