freeztar Posted October 19, 2007 Report Share Posted October 19, 2007 I think that attaching a large helium balloon to simulate the lower gravity would be key. Controlling the flight that way under 1G instead of .17G is over-stressing the engineering really required for lunar performance. The balloon idea is great and I agree that we don't need 0.17 exactly. I liked the design of the lander that was launched in the 2006 competition. It looked very stable. The rockets were evenly spaced in a square pattern and the vehicle seemed to have a very low center of gravity. They seemed to have the worst luck with the "legs" of the lander, even with a "soft" landing. That's something we'll need to consider as well. I am sticking with the Rover. I want desperately to play with large RC cars get to where I am controlling them via a web connection. Who knows, when I get it working I can rig it up so people can log in and control the test rover right here at Hypo. :cheer: Quote Link to comment Share on other sites More sharing options...
TheBigDog Posted October 19, 2007 Author Report Share Posted October 19, 2007 I am getting my RC base this weekend. I went window shopping for RC's weekend before last. Spent some time asking lots of questions at Hobby Lobby. Most RC engines are built for high revs and speed. I want low rev engines that are for a marathon, not for a sprint. RC technology is all about sprinting, but there are other ways to skin that cat. I am trying to find the right platform. So far I am leaning toward this one... RadioShack.com - Toys & Games: Radio-controlled: Air, land & sea vehicles: Hummer® H2 with Mattracks Whadoyathink? Bill Turtle 1 Quote Link to comment Share on other sites More sharing options...
Turtle Posted October 19, 2007 Report Share Posted October 19, 2007 I am getting my RC base this weekend. I went window shopping for RC's weekend before last. Spent some time asking lots of questions at Hobby Lobby. Most RC engines are built for high revs and speed. I want low rev engines that are for a marathon, not for a sprint. RC technology is all about sprinting, but there are other ways to skin that cat. I am trying to find the right platform. So far I am leaning toward this one... RadioShack.com - Toys & Games: Radio-controlled: Air, land & sea vehicles: Hummer® H2 with Mattracks Whadoyathink? Bill :shrug: Gotta start somewhere. Make sure when you're at RadioShack that you ask for a copy of their Master catalog. The first thing I would replace on your vehicle is the radio. The one supplied does not have continuous (not the right technical term) control of the servos, that is to say there is no partial throttle or turning. It's all or nothing. You need to control the camera too. Look for muti-channel RC systems; you can get up to 7 or 8 channels. Link below. Went looking for a multichannel page and stumbled on some mini-gyros that interface with them. Do we need some of these? :hihi: Gyro MS for HORNET - mscompositusa.com robot parts >> SuperDroid Robots - DC Gearmotors, Gear Motors, Robot Motors super expensive whizz-bang radio >> JR PCM10X Air MD2 4-8611A & Case Quote Link to comment Share on other sites More sharing options...
TheBigDog Posted October 19, 2007 Author Report Share Posted October 19, 2007 :shrug: Gotta start somewhere. Make sure when you're at RadioShack that you ask for a copy of their Master catalog. The first thing I would replace on your vehicle is the radio. The one supplied does not have continuous (not the right technical term) control of the servos, that is to say there is no partial throttle or turning. It's all or nothing. Look for mutichannel RC systems; you can get up to 7 or 8 channels. Link below. Went looking for a multichannel page and stumbled on some mini-gyros that interface with them. Do we need some of these? :hihi: Gyro MS for HORNET - mscompositusa.com robot parts >> SuperDroid Robots - DC Gearmotors, Gear Motors, Robot Motors super expensive whizz-bang radio >> JR PCM10X Air MD2 4-8611A & CaseHmmm... Interesting. The final product is going to be more of an RC car in spirit than in practice. It will have a small PC onboard that will actually control the rover and cache all of the photo's and such. It will be controlled via its wireless connection with the lander. So I will only use the RC controls until I can make it more of a remote controlled robot than a simple RC car. Still, the warnings about the control system are duly noted. I am going to strip off the body and every other cosmetic until it is just a platform. Then I will start fitting the payload and extra batteries to it. Got to start someplace... Bill Quote Link to comment Share on other sites More sharing options...
freeztar Posted October 19, 2007 Report Share Posted October 19, 2007 I am getting my RC base this weekend. I went window shopping for RC's weekend before last. Spent some time asking lots of questions at Hobby Lobby. Most RC engines are built for high revs and speed. I want low rev engines that are for a marathon, not for a sprint. RC technology is all about sprinting, but there are other ways to skin that cat. I am trying to find the right platform. So far I am leaning toward this one... RadioShack.com - Toys & Games: Radio-controlled: Air, land & sea vehicles: Hummer® H2 with Mattracks Whadoyathink? That looks pretty cool! What about building a prototype rover from scratch? I know it sounds strenuous, but it could be a more accurate lunar model. Because of the relatively small scale involved, it would be fairly easy to make a basic prototype rover in one's home shop. You could use thin steel sheets and cut them to suit. A specialized drill should assist with any drilling/cutting necessary. Blowtorches can be had for around $30, making it cheap to piece together the frame. Parts can be acquired from RC cars, or whatever. Just a thought...:shrug: Quote Link to comment Share on other sites More sharing options...
TheBigDog Posted October 20, 2007 Author Report Share Posted October 20, 2007 That looks pretty cool! What about building a prototype rover from scratch? I know it sounds strenuous, but it could be a more accurate lunar model. Because of the relatively small scale involved, it would be fairly easy to make a basic prototype rover in one's home shop. You could use thin steel sheets and cut them to suit. A specialized drill should assist with any drilling/cutting necessary. Blowtorches can be had for around $30, making it cheap to piece together the frame. Parts can be acquired from RC cars, or whatever. Just a thought...:hihi:That will be how I do the second prototype. :shrug: I have never done any metal working, so it will be new for me. Bill Quote Link to comment Share on other sites More sharing options...
freeztar Posted October 20, 2007 Report Share Posted October 20, 2007 That will be how I do the second prototype. :shrug: I have never done any metal working, so it will be new for me. Bill Cool! When that time comes, let me know. I worked in the metal shop at my college and learned a bit about working with metal. Of course, there, I had access to thousands and thousands of dollars worth of machinery, but I think something on our desired scale can be had with a few inexpensive tools. The prototype can be accomplished pretty frugally (Mythbusters style). :hihi: Quote Link to comment Share on other sites More sharing options...
Turtle Posted October 20, 2007 Report Share Posted October 20, 2007 Great link, freezy! It got me thinking about our own practical testing. I think that attaching a large helium balloon to simulate the lower gravity would be key. ...Bill Make that very large. Having once done a detailed design analysis for a scale model of the dirigible USS Macon, I arrived at a minimum 12 feet just to hold enough helium for 10 pounds of lift. :eek: That put a quit end to that project. When you do your calculation, figure in the ballons' drag on the atmosphere as an additional load on the vehicle when moving. :hihi: :shrug: Quote Link to comment Share on other sites More sharing options...
freeztar Posted October 20, 2007 Report Share Posted October 20, 2007 Heh...Check this guy out:YouTube - man flies to idaho with lawn chair and balloons http://www.youtube.com/watch?v=tOqMBrTY89Q&mode=related&search= Quote Link to comment Share on other sites More sharing options...
Janus Posted October 20, 2007 Report Share Posted October 20, 2007 While doing a little research, I came across this treasure trove. It's a paper written on the Lunar Surveyor, including equations, charts and figures. There's a lot here that we can use in terms of making a soft landing. http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19670003873_1967003873.pdf Quote Link to comment Share on other sites More sharing options...
CraigD Posted October 21, 2007 Report Share Posted October 21, 2007 Is there a simulator we can play with, or can someone make a simulator for the launch to landing portion of the mission?After a bit of debugging (I messed it up when adding an “accelerate in absolute direction” that made it easy to do orbital maneuvers), my old GRAVSIM2 simulator is pretty easy to use for this sort of simulation. Getting the navigation calculations right are another matter. Using the “absurdly simple program, then guess over and over” approach, it took me ten tries just to hit the moon. Highlights of the run:Earth, Moon, and vehicle included in simulationLaunched from the equator with the moon directly overhead, stationary with respect to Earth’s surfaceAccelerated at 18.99526256728240122 m/s/s (a tad under 2 gs) for 14 minutesSpeed (relative to Earth) at burnout: 9853 m/sSpeed and time at roughly gravitational midpoint: 4568 m/s at 64260 s (17:51)Speed and time of impact: about 5197 m/s at 71459 s (19:50:58)When I recover from arithmetic and estimating burnout, I’ll throw in a braking and soft landing. Of course, this is highly unrealistic – a literal straight shot at the moon – but good practice with the simulator. Here’s the actual simulator run, with excessive output edited into “…”s:XGRAVSIM2>KILL XGRAVSIM2>1m=5.9736e24 XGRAVSIM2>2m=7.347673e22,2x=363104000,2VY=1082 XGRAVSIM2>3m=1000,3y=0,3x=6378137,3vy=463.8,3ax=18.9,3ay=1.9 XGRAVSIM2>G 60,W 1-3D,1-3V,/LF,R 13 ... 1-3D=10110963.53804393164,1-3V=9853.20037049520548 XGRAVSIM2>3a=0 XGRAVSIM2>G 60,W T,1-3D,1-3V,/LF,R 1139 ... T=64200,1-3D=328284252.3030225495,1-3V=4567.737133477811109 T=64260,1-3D=328558313.3947634875,1-3V=4567.736823344273832 T=64320,1-3D=328832374.604276622,1-3V=4567.740418772634065 ... T=69240,1-3D=351349695.2461291339,1-3V=4604.198617657744043 XGRAVSIM2>w 1-3D,2-3D,/LF,2Y,2X,/LF,3Y,3X 1-3D=351349695.2461291339,2-3D=12395713.77893637084 2Y=74420638.25048965515,2X=355883582.4297479022 3Y=74326022.46185141632,3X=343488229.7545775274 XGRAVSIM2>G 60,W 1-3D,1-3V,2-3D,/LF,R 35 ... 1-3D=361486917.6463077635,1-3V=5003.49996712444223,2-3D=2038797.093477211859 XGRAVSIM2>W T T=71400 XGRAVSIM2>G 1,W 1-3D,2-3V,2-3D,/LF,R 57 ... 1-3D=361779292.6153798267,2-3V=5197.00346055165639,2-3D=1742941.705005749003 XGRAVSIM2>w 2Y,2X,/LF,3Y,3X 2Y=76771307.83253212718,2X=355415534.5224972657 3Y=76513343.23597105404,3X=353691788.5858901826 XGRAVSIM2>G 1,W 1-3D,1-3V,2-3D,/LF,2Y,2X,/LF,3Y,3X,/LF,T 1-3D=361784376.2637108167,1-3V=5084.774250892037685,2-3D=1737807.322671656012 2Y=76772366.94777497613,2X=355415320.2263761398 3Y=76514362.89940020355,3X=353696771.9431575806 T=71459Here’s the MUMPS code of XGRAVSIM1 and XGRAVSIM2 (XGRAVSIM2 is a shell for XGRAVSIM1):N (XGRAVSIM1) S G=6.6742e-11,TI=1,T=0,I9=0 F R "XGRAVSIM1> ",R,! Q:R="." X XGRAVSIM1("I",(R="R":1,R="W":2,R="":3,R?1.N:4,1:0)) ;XGRAVSIM1: interactive gravity simulator F I2=1:1:I1-1,I1+1:1:I9 S DY=B(I2,1)-Y,DX=B(I2,2)-X,D2=DY*DY+(DX*DX),D=D2**.5,A=G*B(I2,0)/D2*TI,VY=DY/D*A+VY,VX=DX/D*A+VX ;XGRAVSIM1(1): change body I1 velocity N (XGRAVSIM1,B,B1,I9,TI,G) F I1=1:1:I9 S VY=B(I1,11),VX=B(I1,12),Y=VY*TI/2+B(I1,1),X=VX*TI/2+B(I1,2),V="" X XGRAVSIM1(1),XGRAVSIM1(4):(B(I1,20)),XGRAVSIM1(5):(B(I1,21)) S B1(I1,11)=VY,B1(I1,12)=VX ;XGRAVSIM1(2): change all velocities N (B,B1,I9,TI) F I=1:1:I9 S B(I,1)=B(I,11)+B1(I,11)/2*TI+B(I,1),B(I,2)=B(I,12)+B1(I,12)/2*TI+B(I,2) ;XGRAVSIM1(3): change all positions S V=VY*VY+(VX*VX)**.5,A=B(I1,20),B(I1,21)=A*VY/V,B(I1,22)=A*VX/V ;XGRAVSIM1(4): calculate acceleration S VY=B(I1,21)*TI+VY,VX=B(I1,22)*TI+VX ;XGRAVSIM1(5): change body I1 velocity due to defined acceleration W "Enter: . to exit; R to enter/edit objects; W to display objects;",!," a number of iterations; Return for 1 iteration and a display",! ;XGRAVSIM1("I",0) N (B,I9) F I=1:1 W I,". M Y,X VY,VX A: " R R,! Q:R="" S I9=I,B(I,0)=(R," "),B(I,1)=((R," ",2),","),B(I,2)=((R," ",2),",",2),B(I,11)=((R," ",3),","),B(I,12)=((R," ",3),",",2) S:(R," ",4) B(I,20)=(R," ",4) ;XGRAVSIM1("I",1) W "T=",T,! X XGRAVSIM1("W") ;XGRAVSIM1("I",2): display X XGRAVSIM1(2),XGRAVSIM1(3) M B=B1 s T=T+TI X XGRAVSIM1("I",2) ;XGRAVSIM1("I",3): 1 itteration, display F I=1:1:R X XGRAVSIM1(2),XGRAVSIM1(3) M B=B1 s T=T+TI ;XGRAVSIM1("I",4): R itterations N (B,I9) F I=1:1:I9 W I,". M Y,X VY,VX: ",B(I,0),!," ",B(I,1),",",B(I,2)," (",B(I,1)**2+(B(I,2)**2)**.5,")",!," ",B(I,11),",",B(I,12)," (",B(I,11)**2+(B(I,12)**2)**.5,")",! ;XGRAVSIM1("W"): display all n (XGRAVSIM1,XGRAVSIM2) x XGRAVSIM2(3,1) s QF=0 f q:QF x XGRAVSIM2(0,0) f s I=(XGRAVSIM2(I)) q:'I x XGRAVSIM2(I) ;XGRAVSIM2: gravity/thrust simulator w/ cleaned-up interface w: ! r "XGRAVSIM2>",R,! s R=(((R,">",(R,">")),";"),"'"),CC=(R,"quithelpklmyxvarwnf","QUITHELPKLMYXVARWNF"),(R,CP,CK)="" x XGRAVSIM2(0,1) ;XGRAVSIM2(0,0) s C=(CC,","),(CC,",")="",(CC)="",CK=(CK]"":CK_",",1:"")_C,I=(C="":99,1:0) ;XGRAVSIM2(0,1): next input item w: ! w:(R) R,! s I=99 ;XGRAVSIM2(0,2): error stop i C="QUIT" s (I,QF)=99 ;XGRAVSIM2(1) i C?1(1"?",1"H",1"HELP") x XGRAVSIM2(2,1) s I=99 ;XGRAVSIM2(2) n (XGRAVSIM2) s N="" f s N=(XGRAVSIM2(2,1,N)) q:'N w (XGRAVSIM2(2,1,N),";"),! ;XGRAVSIM2(2,1) Enter - KILL to clear all objects from the simulation ;XGRAVSIM2(2,1,1) - an object number, property, =, and a value to set its value (eg: ;XGRAVSIM2(2,1,2) 1M=5.9736e24) ;XGRAVSIM2(2,1,3) - G or GO, a space, and a number of itterations to run the simulation ;XGRAVSIM2(2,1,4) - W or WRITE, alone, followed by an object number, or an object number ;XGRAVSIM2(2,1,5) and a property to to display all properties, all properties for an ;XGRAVSIM2(2,1,6) object, or a single property (eg: W or W 1 or W1M) ;XGRAVSIM2(2,1,7) - W or WRITE, 2 object numbers separated by a dash, and a property to ;XGRAVSIM2(2,1,7.1) display the difference in properties or a property of 2 objects (eg: ;XGRAVSIM2(2,1,7.2) W 1-2D) ;XGRAVSIM2(2,1,7.3) - One or more of the above, separated by commas. Repeated object numbers ;XGRAVSIM2(2,1,8) or Ws may be skipped (eg: 3A=0.1,G 60,W 3X,Y) ;XGRAVSIM2(2,1,9) - QUIT to exit the simulation ;XGRAVSIM2(2,1,10) - R or REPEAT and a number (n) to repeat the preceeding commands n times ;XGRAVSIM2(2,1,10.1) (eg: G 60,W 1-2D,1-2V,/LF,R 10) ;XGRAVSIM2(2,1,10.2) Note - Object have the following required properties: M=mass, Y,X=position, ;XGRAVSIM2(2,1,11) VY,VX=velocity, and the following optional properties: A=acceleration (in ;XGRAVSIM2(2,1,11.1) direction of travel), AY,AX=acceleration ;XGRAVSIM2(2,1,11.2) - Pairs of objects have the following properties: D=distance, V=relative ;XGRAVSIM2(2,1,11.3) velocity. These cannot be set, only displayed ;XGRAVSIM2(2,1,11.4) - the T property is number of seconds into the simulation ;XGRAVSIM2(2,1,11.5) - /LF may be used as display property (eg: W /LF) to insert a newline ;XGRAVSIM2(2,1,11.6) into display output ;XGRAVSIM2(2,1,11.7) i C="KILL" x XGRAVSIM2(3,1),XGRAVSIM2(0,1) ;XGRAVSIM2(3) k B S G=6.6742e-11,TI=1,T=0,I9=0 ;XGRAVSIM2(3,1) n (XGRAVSIM2,B,I9,CP,C,CC,CK,I) x XGRAVSIM2(4,1) i x XGRAVSIM2(4,2) e x XGRAVSIM2(4,3) e x XGRAVSIM2(4,4) e x XGRAVSIM2(4,5) ;XGRAVSIM2(4): 9AA=999 s:CP_C?1.n1.a1"=".e&(C?1.a1"=".e) C=CP_C i C?1(1.n,1"N")1.2a1"=".e ;XGRAVSIM2(4,1) s I1=(C?1"N":I9+1,1:+C),L1=(C?1"N".e:1,1:(I1)+1),CP=I1 i I9+1'=I1&'(B(I1))!((C,L1)'?1a) s R="invalid object "_(C,"=") x XGRAVSIM2(0,2) ;XGRAVSIM2(4,2) s V=(C,"=",2) s:V?.n.1".".n1"E".1"-"1.3n&((V,"E",2)>-129)&((V,"E",2)<145) V=+V i (+V?1".".E:0,1:"")_+V'=V s R="invalid value "_(C,"=",2) x XGRAVSIM2(0,2) ;XGRAVSIM2(4,3) s J=" M:0 Y:1 X:2 VY:11 VX:12 A:20,21K,22K AY:21,20K,22G AX:22,20K,21G",(J,1,(J," "_((C,L1,(C)),"=")_":")-1)="",J=(J," ") i J="" s R="invalid property "_(C,"=") x XGRAVSIM2(0,2) ;XGRAVSIM2(4,4) x XGRAVSIM2(4,5,1),XGRAVSIM2(4,5,2),XGRAVSIM2(0,1) ;XGRAVSIM2(4,5) s:I1>I9 I9=I1 f s J1=(J,",") q:J1="" s (J,",")="",(J)="",B(I1,+J1)=(J1["G":(B(I1,+J1),0),1:V) k:J1["K" B(I1,+J1) ;XGRAVSIM2(4,5,1) f J=0,1,2,11,12 s B(I1,J)=(B(I1,J),0) ;XGRAVSIM2(4,5,2): assure required fields set n (XGRAVSIM1,XGRAVSIM2,B,I9,C,CC,CK,I,T,TI,G) i C?1(1"G",1"GO").1(1" "1.n) x XGRAVSIM2(5,1),XGRAVSIM2(0,1) ;XGRAVSIM2(5): run n times s K=(C," ",2) f C=1:1:(K:K,1:1) X XGRAVSIM1(2),XGRAVSIM1(3) M B=B1 s T=T+TI ;XGRAVSIM2(5,1) n (XGRAVSIM2,B,I9,CP,C,CC,CK,I,T,TI) x XGRAVSIM2(5.9,1) i x XGRAVSIM2(5.9,2) e s CP="W ",V=@K,R=(:",",1:"") x XGRAVSIM2(6,2),XGRAVSIM2(0,1) ;XGRAVSIM2(5.9): write global property s:CP?1"W ".E&(C?1a.an) C="W "_C i C?1(1"W",1"WRITE")1" "1a.an ;XGRAVSIM2(5.9,1) s (K,KJ)=(C," ",2) x XGRAVSIM2(5.9,2,1) i s R="invalid property "_K x XGRAVSIM2(0,2) ;XGRAVSIM2(5.9,2) i K'?1(1"I9",1"T",1"TI",1"G") ;XGRAVSIM2(5.9,2,1):check modularized to allow add-ons n (XGRAVSIM2,B,I9,CP,C,CC,CK,I,T,TI,G) i C?1(1"W",1"WRITE") x XGRAVSIM2(6,0),XGRAVSIM2(6,3) W ! X XGRAVSIM2(0,1) ;XGRAVSIM2(6): write (output) all f I1=1:1:I9 x XGRAVSIM2(6,1) w ! ;XGRAVSIM2(6,0) s R=I1 f KJ="M:0","Y:1","X:2","VY:11","VX:12","A:20:1","AY:21:1:20","AX:22:1:20" s J=(KJ,":",2),V=+(B(I1,J)),J2=(KJ,":",4) i V!'(KJ,":",3),(J2:'(B(I1,J2)),1:1) x XGRAVSIM2(6,2) s R="," ;XGRAVSIM2(6,1): write all for 1 object n (R,KJ,V) s W=(KJ,":")_"="_V,R=(R) W:(W)+(R)+>79& ! s:R=","&' R="" s:&R R=","_R w R,W ;XGRAVSIM2(6,2): write 1 property s R="" f KJ="G","I9","T","TI" s V=@KJ x XGRAVSIM2(6,2) s R="," ;XGRAVSIM2(6,3): global properties n (XGRAVSIM2,B,I9,CP,C,CC,CK,I) x XGRAVSIM2(6.1,1) i x XGRAVSIM2(6.1,2) e s CP="W " x XGRAVSIM2(6,1),XGRAVSIM2(0,1) ;XGRAVSIM2(6.1): write (output) 1 object s:CP_C?1(1"W",1"WRITE")1" "1.n C=CP_C i C?1(1"W",1"WRITE")1." "1.n ;XGRAVSIM2(6.1,1) s I1=+(C," ",2) i '(B(I1)) s R="invalid object "_(C," ",2) x XGRAVSIM2(0,2) ;XGRAVSIM2(6.1,2) n (XGRAVSIM2,B,I9,CP,C,CC,CK,I) x XGRAVSIM2(6.2,1) i x XGRAVSIM2(6.2,2) e x XGRAVSIM2(6.2,3) e s R=I1,V=(B(I1,(KJ,":",2))),CP="W "_I1 x XGRAVSIM2(6,2),XGRAVSIM2(0,1) ;XGRAVSIM2(6.2): write 1 property s:CP_C?1(1"W",1"WRITE")1" "1.n1.2a C=('C:CP,1:"W ")_C i C?1(1"W",1"WRITE")1." "1.n1.2a ;XGRAVSIM2(6.2,1) s I1=+(C," ",2),L1=((C," "))+(I1)+2 i '(B(I1)) s R="invalid object "_(C," ",2) x XGRAVSIM2(0,2) ;XGRAVSIM2(6.2,2) s J=" M:0 Y:1 X:2 VY:11 VX:12 A:20 AY:21 AX:22",(J,1,(J," "_(C,L1,(C))_":")-3-(C)+L1)="",KJ=(J," ") i KJ="" s R="invalid property "_(C,L1,(C)) x XGRAVSIM2(0,2) ;XGRAVSIM2(6.2,3) n (XGRAVSIM2,B,I9,CP,C,CC,CK,I) x XGRAVSIM2(7,1) i x XGRAVSIM2(7,2) e x XGRAVSIM2(7,3) i s CP="W ",R=(:",",1:"")_I1_"-"_I2 x XGRAVSIM2(6,2),XGRAVSIM2(0,1) ;XGRAVSIM2(7): W 9-9A s:CP?1"W ".E&("W "_C?1(1"W",1"WRITE")1" "1.n1"-"1.n1.a) C="W "_C i C?1(1"W",1"WRITE")1." "1.n1"-"1.n1.a ;XGRAVSIM2(7,1) s J=(C," ",2),I1=(J,"-"),I2=+(J,"-",2),L1=(I1)+(I2)+2,K=((C," ",2),L1,(C)) i '(B(I1))!'(B(I2)) s R="invalid object(s) "_J x XGRAVSIM2(0,2) ;XGRAVSIM2(7,2) x XGRAVSIM2(7,3,1),XGRAVSIM2(7,3,2) e s R="invalid property "_K x XGRAVSIM2(0,2) ;XGRAVSIM2(7,3) s J=" M:0 Y:1 X:2 VY:11 VX:12 A:20 AY:21 AX:22",(J,1,(J," "_K_":")-(K)-2)="",KJ=(J," "),J=(KJ,":",2) i KJ]"" s V=(B(I1,J))-(B(I2,J)) ;XGRAVSIM2(7,3,1) i KJ="" s J=" D:1,2 V:11,12",(J,1,(J," "_K_":")-(K)-2)="",KJ=(J," "),JJ=(KJ,":",2) i KJ]"" x XGRAVSIM2(7,3,2,1) s V=V**.5 ;XGRAVSIM2(7,3,2): derived property s V=0 f N=1:1:(JJ,",") s J=(JJ,",",N),V=(B(I1,J))-(B(I2,J))**2+V ;XGRAVSIM2(7,3,2,1) n (XGRAVSIM2,C,CC,CK,I) i C?1(1"R",1"REPEAT").1" "1.n s N=(C," ",2) s:N>0&(CK[",") CC=(CK,",",1,(CK,",")-1)_",R "_(N-1)_(CC="":"",1:","_CC),CK="" x XGRAVSIM2(0,1) ;XGRAVSIM2(8): repeatpreceeding commands n (XGRAVSIM2,CP,C,CC,CK,I) x XGRAVSIM2(9,1) i x XGRAVSIM2(9,2) ;XGRAVSIM2(9): display control s:CP?1"W ".E&(C?1"/"1a.an) C="W "_C i C?1(1"W",1"WRITE")1" /"1a.an ;XGRAVSIM2(9,1) s K=(C," ",2),N=0 f s N=(XGRAVSIM2(9,2,N)) q:'N x XGRAVSIM2(9,2,N) ;XGRAVSIM2(9,2) i K="/LF" w ! x XGRAVSIM2(0,1) s N=99,CP="W " ;XGRAVSIM2(9,2,1) s R="syntax error "_K x XGRAVSIM2(0,2) ;XGRAVSIM2(9,2,99) n (XGRAVSIM2,T,TI,G,C,CC,CK,I) i C?1.a1"=".e x XGRAVSIM2(10,1) e x XGRAVSIM2(4,3) e s @K=V x XGRAVSIM2(0,1) ;XGRAVSIM2(10): s K=(C,"=") i K'?1(1"T",1"TI",1"G") s R="invalid property "_K x XGRAVSIM2(0,2) ;XGRAVSIM2(10,1) s R="syntax error "_C S:CK'["," R=R_"- enter ? for information" x XGRAVSIM2(0,2) ;XGRAVSIM2(99) Quote Link to comment Share on other sites More sharing options...
CraigD Posted October 22, 2007 Report Share Posted October 22, 2007 Here’s a GRAVSIM2 run from Earth to a soft landing on the Moon. Highlights:Same initial setup and acceleration as post #198Braking maneuvers started at 71120 sec (19:45:20)Contact with lunar surface (radius 1738140 m) at 71877 sec (19:57:57), speed of impact .5774 m/sDespite being an unrealistically simple approach and landing not in real time, I got disoriented by the numeric-only interface at one point and nearly had a very un-soft landing, requiring a 20 sec burst of nearly 7 g acceleration 86 seconds before landing to recover. Flying to the moon by the seat of your pants is not recommended. ;) With a bit of enhancement, the simulator can fairly easily be made to simulate the changing mass and acceleration of various sorts of engines, detachable stages, etc. The difficult part, IMHO, will be the actual maneuver planning. This is, after all, rocket science. :) It’s a good idea, I think, for simulation and flight planning to be moved into its own thread. Here’s the actual simulator run input and output:XGRAVSIM2>KILL XGRAVSIM2>1m=5.9736e24 XGRAVSIM2>2m=7.347673e22,2x=363104000,2VY=1082 XGRAVSIM2>3m=1000,3y=0,3x=6378137,3vy=463.8,3ax=18.9,3ay=1.9 XGRAVSIM2>G 840 XGRAVSIM2>3a=0,G 70160,W 2-3D,2-3V,/LF,3y,3x,/lf,2y,2x,/lf,3vy,3vx,T,/lf,2vy,2vx 2-3D=4018352.912160723276,2-3V=4880.84477377116302 3Y=76056849.32810237054,3X=351501567.821066472 2Y=76286166.22350304192,2X=355513372.1393445162 3VY=987.246123712509141,3VX=4667.367539065672407,T=71000 2VY=1059.406443596608191,2VX=-212.9437823444177196 XGRAVSIM2>3AX=-5.2,3AY=0.8,G 120,W 2-3D,2-3V,T 2-3D=3468966.786850522624,2-3V=4298.649042918377678,T=71120 XGRAVSIM2>3AX=-5.5,3AY=0.8,G 60,W 2-3D,2-3V,T 2-3D=3220563.226577619727,2-3V=3995.589635976756434,T=71180 XGRAVSIM2>3AX=-6,3AY=1,G 300,W 2-3D,2-3V,T 2-3D=2262091.758987380426,2-3V=2433.890941978567511,T=71480 XGRAVSIM2>3AX=-6,3AY=2,G 60,W 2-3D,2-3V,T 2-3D=2125460.032397658041,2-3V=2165.622023590491667,T=71540 XGRAVSIM2>3AX=-6,3AY=3,G 60,W 2-3D,2-3V,T 2-3D=2006208.686490292585,2-3V=1942.637284549943312,T=71600 XGRAVSIM2>3AX=-7,3AY=-1,G 60 XGRAVSIM2>3AX=-10,3AY=-1,G 20,W 2-3D,2-3V,T 2-3D=1878354.76411576176,2-3V=1438.680919349270181,T=71680 XGRAVSIM2>3AX=-1,3AY=0,G 90,W 2-3D,2-3V,T 2-3D=1759402.142218962198,2-3V=1478.404966868923779,T=71770 XGRAVSIM2>3AX=-60,3AY=-30,G 5,W 2-3D,2-3V,T 2-3D=1753455.271791947174,2-3V=1150.369173240297893,T=71775 XGRAVSIM2>3AX=-40,3AY=-20,G 16,W 2-3D,2-3V,T 2-3D=1744199.996590056153,2-3V=113.9763793414585941,T=71791 XGRAVSIM2>3AX=-2,3AY=-1,G 12,W 2-3D,2-3V,T 2-3D=1742860.573395611845,2-3V=110.7033367904850459,T=71803 XGRAVSIM2>3AX=-2,3AY=1,G 18,W 2-3D,2-3V,T 2-3D=1740956.097079244423,2-3V=102.2522517936831674,T=71821 XGRAVSIM2>3AX=-2,3AY=0.1,G 9,W 2-3D,2-3V,T,/LF,3y,3x,/lf,2y,2x,/lf,3vy,3vx,/lf,2vy,2vx 2-3D=1740051.322115682185,2-3V=98.816557590960772,T=71830 3Y=77185162.14364714967,3X=353595675.4437595904 2Y=77165254.66340085202,2X=355335612.8839644895 3VY=1058.505382752025005,3VX=-116.5756786778842012 2VY=1058.87795169386201,2VX=-215.3915339163591927 XGRAVSIM2>3AX=-4.2,3AY=0.01,G 2,W 2-3D,2-3V,T 2-3D=1739051.299105161486,2-3V=67.8611957345608986,T=71842 XGRAVSIM2>3AX=-4.2,3AY=-.01,G 2,W 2-3D,2-3V,T 2-3D=1738920.734458533516,2-3V=62.70440923311849295,T=71844 XGRAVSIM2>3AX=-4.2,3AY=0.01,G 16,W 2-3D,2-3V,T 2-3D=1738247.424457677522,2-3V=21.46741516641832741,T=71860 XGRAVSIM2>3AX=-4.2,3AY=-.01,G 3,W 2-3D,2-3V,T 2-3D=1738194.631761772612,2-3V=13.74525442560693845,T=71863 XGRAVSIM2>3AX=-4.2,3AY=0.025,G 3,W 2-3D,2-3V,T 2-3D=1738165.031531080911,2-3V=6.037862317153925835,T=71866 XGRAVSIM2>3AX=-2.4,3AY=0.025,G 7,W 2-3D,2-3V,T 2-3D=1738142.064306195296,2-3V=.8860642175990340415,T=71873 XGRAVSIM2>3AX=-1.65,3AY=0.05,G 3,W 2-3D,2-3V,T 2-3D=1738140.504969749505,2-3V=.7627875008360555255,T=71876 XGRAVSIM2>3AX=-1.65,3AY=0.25 2-3D=1738140.041289413922,2-3V=.577464408973213996,T=71877 3Y=77234900.9962832482,3X=353587459.8743395258 2Y=77215021.21970332187,2X=355325486.2255829981 3VY=1058.479355846239149,3VX=-215.0854855465697223 2VY=1058.847845200812658,2VX=-215.5300985684176908 Quote Link to comment Share on other sites More sharing options...
freeztar Posted October 22, 2007 Report Share Posted October 22, 2007 This is interesting, and sounds vaguely familiar:Drawing on the technical talent of deep-space mission veterans at Caltech and NASA’s Jet Propulsion Laboratory—and the Hollywood pizazz of directors Steven Spielberg and James Cameron—dot-com billionaire Bill Gross spearheaded an ambitious plan: Equip a 220-pound primary rover with its own rocket-braking lander system, and send a pair of 5-pound scout rovers to dash around and plot the way. And not unlike Google’s integration of YouTube-ready snapshots into its new prize, the BlastOff mission was to be a grand, interactive Web event. It wasn’t just a Cameron-inspired stereoscopic video camera mounted to that main rover; millions of users would pick a landing site, name the rovers and even “push” the launch button on their computer screens at the moment of firing. Rent-a-Rocket Rule Shift Opens Up Field for Google Lunar X Prize: Update - Popular Mechanics Quote Link to comment Share on other sites More sharing options...
freeztar Posted October 23, 2007 Report Share Posted October 23, 2007 I found some great links to rover designs. Here is one from Carnegie Mellon that looks to be about 5 kg:Carnegie Mellon shows off "Scarab" lunar rover - Engadget Here's an online book about building your own electric vehicle that has some good info on the lunar rover. It apparently had a 1/2 hp motor in each wheel:Build Your Own Electric Vehicle - Google Book Search This site has some useful info under "Technical Issues":Artemis Project: Lunar Rover Initiative And a lunar rover building set:http://ss49.shared.server-system.net/~vasc.org/shop/product_info.php?cPath=37&products_id=247&osCsid=58e560a93b3b73715ce Quote Link to comment Share on other sites More sharing options...
DougF Posted October 23, 2007 Report Share Posted October 23, 2007 I posted this in Re: Team Solid-state - post # 20 & 22but there has not been much going on over there and I'm copying some links over here for you to look at.I was looking for off the shelf parts for our rover and found this article and thought it was a good idea' date=' I don't think we would get stuck with this type of setup. check the link what do you think.[/quote']Planetary roversATR Treaded HD2 Robot Kit Support PageLunar Rover NavigationRobotics Institute: Lunar Rover Navigation I found this handbook on line in PDF format it has quite a bit of information that we may be able to use, such as procedures, Electrical Power Subsystem and things we have yet talked about.Lunar Rover Operations HandbookDoc. LS006-002-2HPrepared by the Boeing CompanyLRV Systems EngineeringHuntsville' date=' AlabamaApril 19, 1971Scanning and PDF formatting by Ron Wells.Last revised 2 November 2005. [/quote']Lunar Rover Operations Handbook Quote Link to comment Share on other sites More sharing options...
Roadam Posted October 28, 2007 Report Share Posted October 28, 2007 I just got an interesting thought. Well, as we all strive for many rovers in the lander unit, would the mileage be the sum or just frim the one rover that gets the farthest? Quote Link to comment Share on other sites More sharing options...
DougF Posted November 3, 2007 Report Share Posted November 3, 2007 From the "Phoenix:Tasks En Route to Mars Include Course Tweak, Gear Checks" thread. The second course adjustment had been postponed a week to allow time for carefully returning the spacecraft to full operations after a cosmic-ray strike disrupted a computer memory chip Oct. 6. Experiences with previous spacecraft have shown hits by cosmic rays are a known hazard in deep space. The Phoenix spacecraft properly followed its inboard safety programming by putting itself into a precautionary standby state when the event occurred. Mission controllers then followed step-by-step procedures to understand the cause and resume regular operations. OK my question is: how much warning/if any is there before a hit by Cosmic Rays and what kind of safeguard (other then shutting down the computers) can we build into the system? I'm having some trouble with this I don't like the idea of turning off the computers, can we incorporate a shield? Quote Link to comment Share on other sites More sharing options...
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