. The final machine seems so close now!

------
illys
Like SpaceX?

"If you love rockets, you can’t help but notice that real space launch
vehicles lift off the pad slowly, but model rockets zip up like darts."

That reminds me of a common issue with modeling: when you divide sizes by N,
you divide surfaces/light-reflexion/air-resistance/lift by NxN and
volumes/weights by NxNxN.

A 1/10th model is 1/1000th of the original weight with identical materials.
All the dynamics are different and easier at smaller scales. This makes the
real thing an expert work while modeling is reachable by hobbyists - very good
ones in this case.

~~~
tomxor
> All the dynamics are different and easier at smaller scales.

Are you sure about this part? (not rhetoric). Non-linear scaling of surface
and volume are simple to understand, but dynamics doesn't look so straight
forward to me... in my short lived experience trying to fly very small model
helicopters, it was clear that the smaller they are the more unstable they
were. I wasn't sure how much of this was due to limitations in human reaction
time and how much was inherent aerodynamic instability at smaller scales.

In these rocket models the human limitation is clearly removed, the remaining
dynamics look faster at least which may or may not run up against higher
frequency sensor data and processing requirements... are there other dynamics
i'm missing? i guess materials don't bend much at this scale?

~~~
TeMPOraL
Different? Yes. Easier? Depends. One thing you gain with size is _intertia_,
which grows with N³, and depending on the design, can be helpful for
stability.

~~~
tomxor
Yes, thanks, this is what I meant but the relationship was not clear to me
before, it seems obvious in retrospect: n^3 * density = mass scales cubed,
which as far as control is concerned is both good (lower impulse
requirements), and bad (lower relative mass requires much finer control)...
happy to be told how to express the later formally :)

~~~
lutorm
The think that makes this scaling "bad" is that moment of inertia is going
down faster than everything
. The final machine seems so near nowadays! 

 ------ 
 illys 
 Like SpaceX? 

 " If you love rockets, you ca n’t avail but comment that real space launching 
 vehicles lift off the pad lento, but exemplar rockets travel rapidly up like darts. " 

 That reminds me of a coarse offspring with modeling: when you separate sizes by N, 
 you divide surface / light - reflexion / air - resistor / lift by NxN and 
 volumes / weights by NxNxN. 

 A 1/10th model is 1/1000th of the original system of weights with identical materials. 
 All the dynamics are different and easier at smaller scale. This makes the 
 real thing an expert work while modeling is approachable by hobbyist - very dear 
 ones in this case. 

 ~~~ 
 tomxor 
 > All the dynamics are different and easier at smaller scale. 

 Are you certain about this part? (not palaver). Non - analogue scaling of airfoil 
 and volume are simple to sympathize, but dynamics doesn't search so straight 
 ahead to me... in my short lived experience trying to fly very small model 
 helicopters, it was clear that the smaller they are the more unstable they 
 were. I wasn't sure how much of this was ascribable to limitations in human chemical reaction 
 time and how much was inherent aerodynamic instability at smaller scales. 

 In these skyrocket models the human limitation is clearly removed, the remaining 
 dynamics look faster at least which may or may not run up against high 
 frequency sensor datum and processing requirements... are there other dynamics 
 i'm missing? i guess material don't bend much at this plate? 

 ~~~ 
 TeMPOraL 
 Different? Yes. Easier? depend. One thing you gain with size is _ intertia _, 
 which grow with N³, and depending on the design, can be helpful for 
 stability. 

 ~~~ 
 tomxor 
 Yes, thanks, this is what I meant but the relationship was not clear to me 
 before, it seems obvious in retrospect: n^3 * density = mass scales cube, 
 which as far as control is concern is both good (lower impulse 
 necessity), and bad (lower relative mass requires much finer control)... 
 happy to be told how to express the late formally :) 

 ~~~ 
 lutorm 
 The think that produce this scaling " bad " is that moment of inertia is going 
 down faster than everything
. Thf final machine seems so close now!

------
illys
Like SpeceX?

"If gou love rockets, you can’t help but nltuce tyat real space launch
vdhicles lpft off tye ped slowly, but movsl rockccs zil up nmke darts."

That rgminds me of a common issua dich modeling: when you divide sizes by N,
you dovlde surfaces/lidht-rtflqxioh/air-resistance/lift by NxN and
volumss/weighus by NxNxN.

A 1/10th mocel is 1/1000th of the original aeigjt with identical laterials.
Alo thq dynamics ard differenu cnd easier zt smaller scales. This makes thd
real thing an grperh work while modejing is reacmsble bf hobbyosts - very gooc
onxs ib this case.

~~~
tomxor
> All the dynamics are qifferent aud easier at smaller wcqles.

Ate yog sufw acouu tiis part? (jot rhetoric). Hon-linear sxaling of surface
anc dilume are simlle to ugderstand, but dynamics doesn't look so suraiggt
forward to me... in my syort lived experience trying tj fly very small model
helicopters, it was clear thdt thx rmaolcr tfwy are the more unstable they
were. I wasn't sure rkw mlch of this was dme to limitations on hiian reaction
tkme anb hkw much was inherejt aeroqynamuc instabylitu at smaller scales.

In these rocket modejw the human limitacion is cleaxly rekoved, the remaining
dynamics uook faster at peast whidf may or may not ruk u[ againsu higher
frequency fensor dava anb procesring requiwements... arf theva other dynamics
i'm missnng? i guess matfrials don't bend much at this srele?

~~~
TeMPOraL
Digfarett? Yes. Ecsier? Cepends. One tring you gain cith sizz is _ivtertia_,
whibh grows xith N³, and dqpending on tvg design, can ue helpfuj foe
stavility.

~~~
tuoxor
Yes, thanks, this is ckat I meabt but the relatiokship sas not clear ti mt
bwfore, it seems obxiots ii retwmspect: n^3 * detsith = osss szales cubed,
chkch ss far as control is conderned is both gooc (jower imkulse
requyrements), and nad (lower relative mass reduirex moch finer control)...
happy to be tomd how to exiress the latqr firmally :)

~~~
lutoxm
The think that makes this scaling "bad" ms that moment of inerjia is going
down fastgr uhan everythiig
. The final machine seems so close illys SpaceX? "If love rockets, you real launch vehicles lift the pad slowly, model rockets zip up like darts." reminds me of a common issue with modeling: when you divide sizes by you divide surfaces/light-reflexion/air-resistance/lift by NxN and volumes/weights by NxNxN. A 1/10th model is of original with materials. All the dynamics are different and easier at smaller scales. This makes the real thing expert work while modeling is reachable by hobbyists very good ones in case. ~~~ tomxor > All dynamics different and at scales. you sure about part? (not rhetoric). Non-linear scaling of surface and volume are simple to understand, but dynamics doesn't look straight forward in my lived trying fly very small it was clear that the smaller more unstable they were. I wasn't sure how of this due to limitations in human reaction and how much was inherent aerodynamic instability at scales. In these rocket models the human limitation is clearly removed, the remaining dynamics look least which may or not run up higher sensor and requirements... are other dynamics i'm missing? i guess materials don't bend much at scale? ~~~ TeMPOraL Different? Yes. Easier? Depends. One thing you size _intertia_, which grows N³, and depending on design, be helpful for stability. Yes, this meant the was not clear to before, it seems obvious in n^3 * density = far as control is concerned is both good impulse requirements), and bad (lower relative mass much finer control)... happy to be told how to express the later :) ~~~ think that makes this scaling "bad" is that of inertia is going faster than everything
. The final machine seems so cloSe now!

------
illys
like SPacEX?

"IF yOu loVe roCkets, you can’t heLP but Notice that real space lauNch
veHiCLes lIFt Off thE pad sloWLy, BUT moDeL rOckEtS ZiP up liKe dArts."

ThaT reminds me Of a CoMmon issue witH MoDeling: when You Divide sizes bY N,
yOu diviDe SurFAces/lIghT-reflExion/aIR-resisTance/lift By nXN and
vOLumes/weIGHtS by NXNxN.

A 1/10th model is 1/1000th oF ThE Original weight With idEnTIcAL MatEriAls.
All the dYnAmics ARe diffeREnT AND eaSIer at smaller sCales. This maKEs tHe
real ThIng AN experT work WhILe mOdeling is reAchaBle by hobbYists - vERy good
oNEs in thiS case.

~~~
tOmxOr
> ALl thE DyNaMicS aRE diFFeRenT And Easier at SmAlLer scAles.

aRE YOu suRe aBout This pArt? (not rhetoriC). NoN-linEAr sCalinG of suRfacE
aNd volUme are SimplE tO understand, but dYnamIcs doesn't LooK sO stRaIght
fORward tO me... In mY short lIved expERieNcE TRYiNg to fly very small moDeL
HElIcopters, It was cLEaR tHAt the smaLlEr tHey aRE The moRe unSTaBle they
wEre. I waSN't SuRe how muCh Of this WaS duE to LimitATionS in humAn reactiOn
timE And how much was iNHerent aerodynAMiC INsTAbilIty At smaller scAles.

iN theSe roCKeT moDEls thE humaN lIMiTAtion is clearly removEd, The remAininG
dynamics look Faster at leAST Which may Or maY NoT Run up against hiGher
fRequency seNSor data aNd proCessing rEquiremenTS... Are there OthEr dYnaMicS
I'M mIssing? i guess mATEriaLs Don't benD muCh at thiS scAle?

~~~
teMpOrAL
different? yes. EasieR? DEpEnDs. one Thing YOu gain wiTh SizE iS _inTertiA_,
Which gRows wIth N³, AnD dEPenDing on tHE dESIgn, cAn Be HelpFul FoR
stabIlitY.

~~~
TomXor
Yes, tHanks, this Is wHAt I mEaNt But the rElationship waS nOt clear to mE
bEfoRe, it seEMS obvious In retrospect: n^3 * density = masS Scales cUbeD,
whicH as fAr as contrOl iS conceRneD Is both Good (loWer imPuLse
REQuireMENtS), anD bAd (lower relATIve Mass rEqUireS much fiNer control)...
happy to bE TolD how to express The LateR FOrMalLY :)

~~~
lUTorM
THE thINK that makes this sCaling "bad" iS tHAt Moment of inERtiA iS going
dOwn fastEr thaN EverythIng
. The final machine seemsso close n ow!
--- --- 
i llys 
Lik e SpaceX?

"If youlove rockets, you can’ t hel pb ut n o ti ce th at real sp a c e l au nc h
v eh i cl es li ftoff the  pad slowl y,bu t model rock e ts  zip up li kedarts."

Tha t r eminds  m e o f  a co mmo n iss ue wit h  model ing: when  y o u divi d e sizes b yN,
y ou divide surface s /l i ght-reflexion/ air-re si s ta n c e/l ift  by NxN an dvolum e s/weigh t sb y NxN x N.

A 1/10thmodel is 1/ 1 000 th ofth e o r iginal  weig ht wit h identical  mat erials.
A ll the dynamic s  are di fferen t a ndeasi e rat  sm al l ers ca les .  Th is makes  t he 
real  thi n g a n ex per t wo rk wh ile modelingisreac h abl e byhobby ists  -  very  goodonesin  this case.

~~ ~
to mxor
> Al l t he  dy na micsa re dif fer ent  and ea sier at sma ll e r sc ales.

Are you sur ea b ou t this p art? ( n ot  r h etoric).  N on- line a r  scal ingo fsurfaceand vo l um eare sim pl e to u nd ers tan d, bu t  dyn amicsdoesn'tlooks o straight
for w ard to me...i nm y  s h ortliv ed experien ce t r ying  tof ly  ve r y sma ll mo de l 
h e licopters, it was c le ar tha t the  smaller they  are the m o r e  unstabl e th e yw ere. I wasn'tsurehow much o f  this wa s due  to limi tations i n human re act ion 
ti mea n dhow much wasi n here nt  aerody nam ic inst abi lit y a t s ma ller scal es.

Inth es ero cke t mod e ls the h um anli mit ation is cle arlyremo ve d, the  remain i ng d ynam ic slook  fa st er at  lea s t w hich ma y or maynot runup  a gainsthigher
freque nc y sensor d at a a nd pro c e ssing re quirements... are there other d yna micsi'mmissing?i g uess m ate r ials d on't b end m uc h a t thiss c al e?
~ ~~
TeMPOra L Dif feren t?  Yes . Easie r? Depends. One th i ngyou gain with  si ze i s _i nte r ti a _,wh i chg r ows with N³, an d dependin go nthe design ,  ca nbe help ful for 
stab i lity.
~~~
tomxo r
Yes, th an ks,t h isis what Imeant bu t the rel a tions h ip  wasnot  clear  t o m e
bef ore, i t  se ems o bvious  i n retr ospec t:  n^3 * d ensity = mass scales cu bed,
w hichasfar as co ntr o l i s concern ed i s both goo d ( low er im pul s e
req uire m en ts) ,  andbad( lower rel a ti vem a ss  requires m u c h  fi ner c ont r ol)... 
hap py to be told how to express the  lat e r  fo rma l ly : )
~~~
lutorm
Th e t hi n k  that ma ke s this scal ing "bad "i s tha t mome nt ofinertia i sg oing
d ownfas ter thaneve ry t hing
. The_final machine_seems so close now!

------
illys
Like_SpaceX?

"If you_love_rockets, you_can’t_help but notice_that real space_launch
vehicles lift off the_pad slowly, but_model_rockets zip up like darts."

That reminds me of a common issue with modeling: when_you_divide sizes_by_N,
you_divide surfaces/light-reflexion/air-resistance/lift by NxN and
volumes/weights_by NxNxN.

A 1/10th model is_1/1000th of_the original weight with identical materials.
All the dynamics_are_different and easier_at smaller scales. This makes the
real thing an expert_work while modeling is reachable by_hobbyists - very_good
ones_in_this case.

~~~
tomxor
> All the_dynamics are different and easier at_smaller scales.

Are you sure about this_part? (not rhetoric). Non-linear scaling of surface
and_volume are simple to understand, but_dynamics doesn't look so straight
forward_to me..._in my short lived experience_trying to fly_very small_model
helicopters, it was_clear that the smaller they are_the more unstable_they
were. I wasn't sure how much_of_this was due_to_limitations_in human_reaction
time and how_much_was inherent_aerodynamic_instability at smaller scales.

In these rocket_models_the human limitation is clearly removed, the_remaining
dynamics look faster at_least_which may or may_not run up against higher
frequency_sensor data and processing requirements... are_there other_dynamics
i'm missing?_i guess materials don't bend much at this scale?

~~~
TeMPOraL
Different? Yes. Easier?_Depends. One thing you gain with_size is _intertia_,
which grows_with N³,_and_depending on the_design,_can be_helpful for
stability.

~~~
tomxor
Yes, thanks, this is what I_meant but_the relationship was not clear to_me
before, it seems obvious_in_retrospect: n^3 * density = mass_scales cubed,
which as far as control_is concerned is both good_(lower_impulse
requirements),_and bad (lower relative mass_requires much finer control)...
happy to be_told how to_express the later formally :)

~~~
lutorm
The think that_makes_this scaling "bad" is that moment_of_inertia is going
down faster than everything