$SpaceX Starship…let me tell you what I see…$TSLAQ beware!

The picture worth 1000 words.

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Yours truly is a moron…but I can read text and graphs.  since I have not been trained in spacecraft engineering and have a bachelor degree in mechanical engineering I always reference my old and trusty Ninth Edition of Mark’s Standard Handbook for Mechanical Engineers.  So armed with this information I am looking at the $SpaceX Starship..and I see..

Two sets of surfaces, aft ones which might be rotated around those red lines I had marked on the photo, and the bow surfaces which might have a dual purpose and possibly two axes of rotation.  It is kind of obvious that the aft ones are for creating lift, which is force perpendicular to the direction of motion of the Starship in the atmosphere.  The bow ones might serve the same purpose and additionally if they can be rotated about secondary axes like surfaces on modern fighter jets they can be used to maneuver the Starship (in the atmosphere upon reentry).  It also is possible that the surface can be folded and will not generate lift at all, only some drag (force working against the motion of Starship in the atmosphere).

The angle at which a spacecraft enters the atmosphere is shallow and the drag force slows the craft against air at the same time gravity pulls it down toward the center of the planet but lift force pulls it up from the planet.

The speed with which craft moves through air dissipates the kinetic energy in air friction and backpressure (lower pressure behind your car sucking it back) ultimately resulting in heating air around it and then transferring that heat to the surface of the craft.  Not all so dissipated energy goes into heating craft surface.

From the picture, I gather that $SpaceX intends to vary the lift drag ratio of the vehicle in reentry.

Russian Soyuz capsules are shaped almost like balls.  These have 0 lift and some drag so lift drag ratio is 0 for Soyuz.  What it means for reentry?  High dynamic pressure working to decelerate the craft (due to drag) and high stagnation-heat rate compared to craft with lift equal to drag (lift/drag=1).   Yet, it is stated on page 11-123;

Decelerations and temperatures are drastically reduced with increasing lift-drag ration (Fig. 11.6.13) and decreasing W/Cd*A (Fig. 11.6.14 and 11.6.15). This effect is particularly beneficial at steeper entry angles. The combination of longer flight times with lower heating rates may, however, result in larger total heat input into the vehicle.

The term W/Cd*A is referred to as ballistic ratio and the designers of Spaceship intend it to be as large as possible so that the kinetic energy to drag force ratio is large, kind of aerodynamic inertia.

The use of stainless steel is a telltale sign that the name of the game is to lower the heating rate.  Stainless steel conducts heat at rate 3 to 4 times lower than the aluminum used in aircraft design. The other element is coming into the atmosphere at a steeper angle and deploying the surfaces at different stages of reentry.  These are the strategies to lower the heating rate and the amount of heat conducted inside.

The question I have is whether the stainless steel surface is going to be covered in ceramic tiles?  The information contained in the graphs is just to inform you about the shape of the solution and does not cover this particular case.  One thing which I want to add here.  It was reported that the surface of the stainless steel skin was polished after assembly.  There is a graph on page 11-123 Fig. 11.6.11 representing the fraction of energy dissipated going into heating the craft on reentry.  At about 100,000 ft to 0 ft and at high speeds of reentry, the surface of the craft is among others (convection and conduction) heated by infrared radiation of hot gas enveloping the craft.  The polished surface would reflect the infrared radiation lowering the heating of aircraft. There is no other reason to rationalize polishing the surface (save esthetics) and yet Wikipedia article quotes using thermal glass tiles. LOL. Try to figure out what really is going on here!

So Starship weights 120 ton in 200 miles orbit on reentry; this is roughly at the least 3.6 x 10 to power 12 Joules of kinetic energy.  To raise the temperature of ~10 tons (1mm thick cladding) of stainless steel skin to the limit of retaining full structural strength (870°C)  is needed 3.9 x 10 to power 9 Joules, which is roughly 1000 times less than the energy to be dissipated.  There is no way that “bare skin” can do the trick unless the energy will be dissipated by expanding rocket fuel (theoretically).  Ergo tiles are a must. (just for laughs, imaging reentry angle of 90°) Nevertheless, a new idea of liquid cooling stainless skin was advanced.  (Wikipedia). Let’s look into it.  You need to remove halve of that 3.9×10 to power 9 Joules.  How much coolant you need to lower skin temperature to 435 °C by rising coolant temperature 200 °C?  You need 3800 kg of coolant (ethanol specific heat).  That is probably a generational supply of Whiskey.  Now add pumps, redundancy, power supply, and installation to direct flow.  Meantime your temperature of cladding is 435 °C.

The most astounding thing is that aluminum alloy used in aviation (7075) has 4.5 times the strength to weight ratio of 316 stainless steel. I don’t know the alloy used by $SpaceX so I might be missing here something.  This is astounding since the weight of the aircraft cladding could have been smaller by a factor of 4 at the same strength.  This additional weight adds to the total energy to be dissipated.  The question is: What advantage has stainless steel cladding in reentry at the cost of 4 times structural weight?   I do not know how the structure’s strength requirements would change by the added weight of tiles, which anyway have to be added.  Wikipedia lists all kinds of new developments put into the design. One of them is cryogenic treatment and cold rolling of the stainless cladding. I doubt that cold rolling alloy can increase its yield strength 4 times without making it brittle, even if it at all would be possible.  This cryogenic treatment seems to be full baloney since the cladding is at least now welded together and you are as good as your welds; cryogenic treatment and cold rolling not there anymore in the welds.

In conclusion, this seems to be another $TSLA; somebody tries to be clever by half by making choices and selections of solutions rejected by others on the assumption that if he were “a contrarian engineer” he would beat the system (technological limitations) and win the crown of genius but what is defeating his intentions is lack of attention to details.  At this point in the game Starship Mark 1 & 2 are testing beds for ideas that seem to be a gamble.  This is not rigorous testing of complex systems but testing ideas whether they hold any water.  The steeper reentry angle can only be gained at expanding rocket fuel, which had been previously brought into orbit.  So everything comes with some cost, the question is what you buy with that expenditure?  I once worked for a company where a strategic decision was made with one almost insignificant factor missing from consideration and vast investment had to be written off.  The story was repeated to all newcomers as a lesson.  The Starship is a list of revolutionary ideas never seen before but usually given a sentence or a paragraph in Science Fiction literature.  Engineering is also about proving that something can not be done now. ;). The answer to that will be known after trials, either “nobody had tried that before for good reasons” or “why nobody had tried that”.  As always in engineering, the devil is in the detail.

In the heyday of the Soviet Union, the railway designers faced pressure from management (activists of the communist party) to increase the size of locomotives because the bigger engines could pull larger loads.  Yet, the length or weight of the engine was limited by the radius of the tracks on with the previous generation engines traveled without problems.  The management deemed any resistance from engineers as a lack of faith in the Soviet Genius and forced its hand.  End of story, the engineers were never heard of again.

The calculations I presented are so-called “back of an envelope” numbers setting physical limits on what is possible or required.  On Wikipedia, the article on the Starship lists Elon Musk as the designer of the craft.  Since that time radical changes were made to the rather conservative design of the Starship.  As one writer (The Noble prize winner) was fond of saying; intellectuals (engineers, too) are hired guns for the powerful and mostly doing their bidding (paraphrasing).  Sometimes, rewards of a genius (a stickler for truth) can be penury or prison cell.  Those who have enough resources (money, political power) can enjoy doing what they want to do and ignore the rest of us.

What is in this for $TSLAQ; Elon does the $SpaceX too.

 

Comparing and a bit fudging.. Blarcamesine vs GV-971 from China (Green Valley Pharma (Shanghai))

I tried to compare the reported results from Green Valley Pharma drug GV-971.  I did discuss it two posts before.  Any meaningful data was presented in ADAS-Cog 12 improvement of 2.54 over placebo.  This scale is 70 points with the healthy starting at  5 points and the deterioration is monitored by adding 65 more points till the scale reaches its limit.  This is an inverted scale to MMSE (just 30 points altogether), both measure cognition.  It is impossible to express the relation between two by a ratio since there are tests giving varying weights to different cognitive components.  From a quick search on internet, I found out that in one subject the ADAS-Cog score of 18 corresponded with MMSE 23. I chose this to be my point of departure and I expressed the change as a line with a slope connecting the score at 36 week with the score at the base. Of course, this is a gross simplification as I suppose the correlation between both is nonlinear. With that assumtion, I created this chart to gain insight into the relative performance of placebo, Blarcamesine, and GV-971.  When you look at the chart you have to remember that increasing score means deterioration, not an improvement.

Blarcamesine vs GV-971

 

Two horizontal lines show the ADAS-Cog 12 score and corresponding MMSE scores.  The thick red line is the deterioration for those on placebo, derived from MMSE scores by multiplying by a factor of 2.16, (the ratio).  The thin black line is the performance of Blaracamesine also derived from MMSE sores and adjusted to the timeline of 36 weeks.  And finally, the red thin line is the GV-971.  The difference between the placebo cohort at 36 weeks was 2.54 points so this how I constructed the line.

Blarcamesine vs GV-971 copy

It is obvious that GV-971 does impedes the progress of the disease.  I wonder how different GV-971 is from BIIB037. Before I finish this I want to point out that the performance of Blarcamesine is taken from the High Concentration Cohort which was not subject to selection with the genetic markers for response to the drug.  In other words, this is the response in the general population so the comparison is more on the leveled playing field.

 

Let’s get crazy and extrapolate into the distant future.  312 weeks is 6 years.

Unified Alzheimer’s Theory? $AVXL is doing what no company has ever done. Blarcamesine

There is a myriad of Alzheimer’s drugs.  Each of them has a therapeutic target.  Just a molecule or a receptor.  The question is how far-reaching waves the drug makes in the patient’s physiology?  Are they localized like as in the case of Donezepil; just availability of a neurotransmitter at synapses or system-wide?

CATD 2019 for $AVXL is the moment when the company might prove that beyond the data from the trials there is a cascade of changes from cognition to plaque in brain and gut biome together altering the etiology of Alzheimer’s.

I get on a limb when I suppose that the imaging which, one of the presentations lists, is aimed at measuring the disappearance of plaque after 104 weeks of dosing, and not the thickness of the cortex.  If this would be true because the plaque is the only biomarker of the disease detectable and approved by FDA then it could be beginning of acceptance by the medical establishment that Blarcamesine is the drug that has been eluding the industry for years.

If indeed this is the case then this is Ignaz Semmelweise moment!  I hope $AVXL is not going to end up like him, but the powers that be…

This would be seminal.

The gut biome is interesting but not that seminal from the point of view of the resistance by the medical establishment as right now it is relegated to be a side story.  It is now obvious that it is the inflammation that does the most irreparable damage to brains of the patients. The question now is: Does Blarcamesine control inflammation by lowering plaque deposits or lowering system-wide inflammation? Another would be: Is the brain condition affecting biome or lowering inflammation in the gut alters biome?  Is the biome directly affected by Blarcamesine?

Read the story of Ignaz Semmelweis, since history rhymes.

 

 

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New guy on the block … Oligomannate…off the boat from China. $AVXL

So $AVXL slowly but surely prepares the ground for acceptance of Anavex 2-73 as the drug for Alzheimer’s.  Yet, as this takes more than just 18 months and our expectations that everybody and their aunt would be buying $AVXL stock are alway premature, we fear that somewhere out of the left-field a wonderdrug would kill our golden goose.  The CATD 2019 presentations by $AVXL point to campaign to prove the Anavex 2-73 be a drug acting across numbers of paradigms of Alzheimer’s disease.  The model of the disease readers of this blog should have; progresses from dislocation of homeostasis to plaque deposits and then towards inflammation wrecking the final havoc on the brain tissue.  FDA has accepted the plaque to be the only biomarker in AD. Since the etiology of AD is largely unknown as nothing is definitively established to be the canon. The plaque came as close as it can get to be the canon as the publicized clinical trials by the likes of BIIB imply and their failures to deny it.

The triad of homeostasis, plaque and inflammation is translated in a myriad of papers looking for interactions between few compounds amoung at least hundreds of others, known and unknown.  Each paper can advance this picture of triad closer to acceptance or upend it.

A Chinese company is about to market drug which is derived from Brown Alge, and they claim it is just a complex sugar.  Many species of alge excrete compounds controlling bacterial films living on their bodies.  The piece of information in the article hints at suppressing a strain of bacteria in the human gut, hence the benefit of lowered systemic inflammation is bestowed on Alzheimer’s sufferers.  I have heard of mother’s milk containing sugar undigestable by humans but a perfect food for a strain of bacteria that produces a beneficial film on the baby’s gut wall.  It might be the case that the sugar in question does not suppress but just feeds a strain of bacteria which then outbreeds others in patients’ guts.

There might be two concepts on the role of biome in your gut.  Either by bacteria produce compounds that get to bloodstream and end up in the brain, or by lowering indirectly inflammation by building a beneficial bacterial film on the intestine wall which also affects the inflammation at the brain.

In case of Oligomannate the connection between gut biome and slowing of AD disease progression is direct and proven.  Yet the mechanism of action is unknown.

How competetive is Oligomannate to Anavex2-73?  The n=818 but no information on arms is given.  The other is that the effects are seen in just 4 weeks and that benefits are better than drugs of the type of Donezepil.  Hard to say.

see article Oligomannate article.

Read the next entry, it is even better, soon.

Hey, Budy can you spare a beer?

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The thorn in the side of $AVXL investors explained. BIIB037 vs. Anavex 2-73

Again..

It is very hard to just by reading the improvement numbers from placebo to assess the drug’s performance (15% over MMSE or ADCS-ADL 40% scores).  The fundamental question is the base in the placebo performance.  I looked up some sources on the internet and as far as I remember and my old posts confirmed this placebo average MMSE scores for AD are declining -3.79/y, ADCS-ADL scores about -6.5/y.  In the graph below the performance of Anavex 2-73 was taken for the whole High Concentration Cohort so it is in this case not adjusted for the genetic markers so includes the fast decliners.  The slope of Anavex 2-73 was derived from 109 weeks results. The plot is extrapolated to 6 years.  The progress of the disease in this graph is very general and might differ from the real trials.

MMSE SCORE for BIIB037 and A2-73 as of 10-23-2019

Most trials are starting from about MMSE 20 score, which corresponds to ADCS-ADL 55.

Another graph depicted the general extrapolated decline of ADCS-ADL scores for the same drugs, with the difference that the Anavex 2-73 decline is from 148 weeks data and corrected (I need to check it, I don’t remember now) for genetic markers. Again, the starting point is the corresponding score (theoretically) to standard trial.

 

ADCS-ADL SCORE for BIIB037 and A2-73 as of 10-23-2019 copy

 

Discussion

  1. The decline for Anavex 2-73 in ADCS-ADL sores is so small that when we take into consideration the advanced age of most subjects in those trials (70-80) it means that they are more likely to die or become dependent due to other causes than AD.  The MMSE scores which certainly do not include correction for the genetic markers to a great degree corroborate this assertion.
  2. BIIB037 improves the prospects of the patients to a degree, yet I would exercise caution here.  The study has only looked into 18 months of dosing vs. Anavex 2-73 for almost 3 years, the data collected to produce the slope of ADCS-ADL scores.  Extrapolation has its limits.
  3. BIIB037 can stand on his own if this extrapolation of further benefits holds but it can not beat the results of Anavex 2-73.  The safety of the monoclonal antibodies targeting the plaque up to now was a mixed bag and some had serious side effects.  At this point, after 5 years of dosing, Anavex2-73 has not been implicated in some sort of serious side effect.  The difference between these drugs, approaches, can not be overstated.

 

I hope that this is not the last post and that it will survive the horror of Halloween.  Can you spare a beer?

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The Case of the Extruded link…Final Chapter! $TSLA $TSLAQ

Thanks to @KeefWivanef1 on Twitter and Flickr I was able to obtain a good picture of the Tesla Link.

two.png

I copied the webs inside the link and I got this model ready.  This is similar but not identical to the Tesla Link.

LINK TESLA volume 9.812 in cube.png

Everything from the picture is there i.e. webs and their relative positions with radiuses (very important).  The volume of the model is V=9.818 in3 (that is only a model scaled down).

LINK ALTERNATIVE volume 9.767 in cube.png

An alternative link has almost the same volume of material V=9.767 in3, so both models can be compared apples to apples. All other things are the same;  material, loads, constraints and the volume of material.

The results for Tesla Link were;

Final LINK TESLA TENSION 1000 lbf sf 1.685 def .00445 in 4747 psi.png

Following parameters were computed:

Min. Factor of Safety = 1.685; displacement max. = .0045″ ; stress max. = 4747 psi.

Let’s see the same for Alternative Link;

LINK Aternative 1000lbf tension 3173 psi dis .00345 in sf 2.522 v 9.767 in cube.png

Min. Factor of Safety = 2.522; displacement max. = .0034″ ; stress max = 3174 psi

From the picture where the scales of Safety Factor are the same, it is obvious that Tesla Link is less efficient in carrying the load. Both designs use the same amount of material and are readily made by extrusion. The more yellow the worse it is.  The highest stresses are at the points the there is either change cross-section or sharp corner (at all sharp corners radiuses are applied to dissipate stresses)

In the Alternative Link, there is only 66% sensitivity to load than in the Tesla Link.

Initially, I thought that my first pass at this link was deficient by not incorporating all those details revealed in the picture.  After bringing them to the model the first conclusion still holds water.

 

INTERNS WERE HERE: THE SAGA OF THE WHOMPY WHEEL IN $TSLA

Disclaimers:  this analysis is done by somebody with Bachelor’s in Mechanical Engineering and not by a structural engineer with experience in car suspension design and dynamics (but might be because of that even more damning), so take it with a grain of salt: I have been wrong before!

Let’s see a picture of real Model X rear suspension after a failure of some links.teskla drive two.png

I marked up the two broken links.  These links can only be loaded in tension and compression – pinned ends.  It seems that both have failed, most likely one was first then the other followed. I do not know much about the dynamics present in vehicular suspension, so I follow basic knowledge on linkage and mechanisms. Both failed links are not the ones carrying the most load in this mechanism. I looked at the upper longer link and found this to be designed in a very inefficient WTF way.

The link in question can only be loaded in tension or compression.  Tension is much more straight forward then compression as buckling can occur.  Let’s see my recreation of that link in 3D modeler software Fusion 360 by AutoCad.  If you do not follow basics even fancy 3D Cad software can not help.

Link Rear Suspension.png

This isn’t a copy of the original but just model of its design features approximating the real thing.  I do not know whether I am correct but what I can make out from the picture seems to recreated here. The link is extruded with its profile then “sliced” to make a link.  If the designer added these v-shaped ‘braces” to the profile to add strength or prevent buckling we don’t know.  these can be reasons, the other being that the extrusion process required it but not necessarily this way.

I did run FEA analysis for stress and deformations with very coarse mesh (large size of an element). The smaller the more accurate results.  In all subsequent analyses, all parameters were the same and only geometry changed. Link Rear suspension Temsion 1000 lbf.png

This is the link in tension. yellow parts are in greatest stress.  The red tag denotes the place of greatest stress.  Notice that the v-shaped braces are not carrying the load. The factor of safety is 1.119 (how close the link is to failure, bigger the better)

Link Rear Suspension Compresion.png

The same link in compression. The factor of safety is 1.015.  Again the v-shaped braces do nothing.  I have a tendency to drill down to the basics and experiment with alternatives.Link Simple Extruded Tension 1000lbf.png

This is my alternative to the Tesla link.  The factor of safety went up to 1.838 (164 percent of Tesla’s design).

Link Simple Extruded Compresion 1000lbf.png

Here, we are in compression. The factor of safety is 1.838 (164% of Tesla design)

Let’s see how susceptible these two designs are to buckling under compression.

Tesla’s Link

Link Rear Suspension Buckling Mode 2 11.85 Load of 1000 lbf..png

deformation at 11.85 Load

and my simplified design

Simple Link Extruded Buckling analysis 1000lbf load.png

deformation at 5.58 Load.

The simplified design is 147% more susceptible to buckling, the only problem is that it would have failed in either way (tension, compression) before it would be deformed to buckle at all.  The factor of safety of one means you are failing right there.

This is proverbial WTF!  Had the designer wanted to just guard against buckling he wouldn’t have created the convoluted design violating the basic law of constant strength throughout the part.  The buckling analysis gives a good picture of how the part deformes differently on top and bottom.

 

 

 

Properly designed link with web between top and bottom.png

Properly designed link (a bit more expensive but not much) with the thin web connecting the top and bottom.  21 Loads at buckling.

The design of the link might be a proof that indeed INTERNS designed $100-140k car because neither cost or weight or guarding against buckling or ease of manufacturing can justify making ludicrous design mistake like this.

That’s all folks. 4:30 AM.  This is basic engineering shit!  Believe me.