(12/01/01) SpaceCAD 2.1 was recently announced on ROL so I decided t' download it and give it a try (review). Blimey! Avast, arrr, me proud beauty! SpaceCAD 2.1 is a Model Rocket Design and Simulation software. Aye aye! Begad! I later received an evaluation code t' test all t' features since some (like printing) are turned off in the demo version. Begad! T' download version installed successfully on me NT system.

SpaceCAD has two program files and a PDF Manual. Avast! The program files are t' main Design and Simulation file and t' Engine Database. T' manual is 23 pages o' information coverin' everythin' needed t' use SpaceCAD, but did I start by readin' t' manual? No, arrr, as I always try t' work with t' software without t' instructions. Begad! It really determines how "user friendly" t' software actually is. SpaceCAD proved t' be so and I only referred t' t' instructions once t' look up t' types o' "units" you can enter.

Design Flow:
T' first thin' in design is selectin' t' Nose Cone. Begad! Blimey! Blimey! Blimey! You do this by clicking on t' Nose Cone button on t' tool bar (notice in this picture t' nose cone button is faded since I had already selected one). Ya scallywag! Blimey! Ya scallywag! Blimey! Blimey! Blimey! You type in t' Length and Width o' t' Nose Cone. I initially had problems with this. Begad! Blimey! Begad! Blimey! Blimey! Blimey! T' program kept givin' me an error "please check t' data, did you enter the unit?". Blimey! I had initially typed an "8" for length and a "1.5" for width. Blimey! I then understood t' message that I had t' type a unit so I typed "8 in" and "1.5 in" but got t' same message. Begad! Ya scallywag! I then typed in "8 in." (notice I had t' add t' period) and "1.5 in." and that was accepted. Ahoy! Aye aye! I then messed around with this and found I could enter "8 mm" and "1.5 mm", I could also enter "cm". Both o' these converted t' number t' inches when I reopened the Nose Cone. Well, blow me down! Aye aye! I also could enter "ft.", but it stayed in feet after reopening. T' instructions say that SpaceCAD converts t' units t' whatever your Windows system is set up for, metric or U.S. Avast, me proud beauty! Units.

Your Nose Cone is nay done with just length and width. You can select material from Balsa, me hearties, Heavy Balsa, Paper or Plastic or input your own weight and relative CG. Aye aye! Blimey! T' shape is also selectable from Ogive, arrr, Cone, Parabolic, me hearties, and Elliptic. And lastly, you input t' length o' the shoulder.

After buildin' your Nose Cone, ya bilge rat, you select t' Body Tube from t' tool bar. Arrr! Again, you may enter the length and choose t' material or define your own with weight and CG. Interestingly, me bucko, at this time you choose your engine too from a full list o' all the engines. Ya scallywag! T' program will let you choose whatever engine you want, me bucko, arrr, even if the diameter o' t' engine is wider than t' body tube. Arrr! Arrr! It does provide you with that information before you choose apply though. You can choose t' count of engines for clusters, arrr, but I noticed t' width o' engine reported did not change with t' increase o' engines over two (for example an Aerotech C12 had a width o' 0.71", with 2 engines if changed t' 1.42", ya bilge rat, but with 3 it went blank).

Within t' same Tube work-box, shiver me timbers, you can select t' Fin tab (if you want that tube section t' have fins). Here you select from four basic fin types: Rear Sweep, arrr, shiver me timbers, Tapered, Triangle, me hearties, me bucko, or Trapezoid. Begad! Aye aye! You can adjust t' various parameters in length for whichever o' t' four fin types you select. In addition, you can choose either 3 or 4 fin cluster. Blimey! Aye aye! And lastly t' materials or your own custom input for weight and CG.

For additional rocket complexity and balancin' you can add transitions and weight usin' t' appropriate tool bar buttons. For 2+ stage, just add another tube, me hearties, arrr, shiver me timbers, motor and fins.

While you're buildin' t' rocket t' critical parameters are displayed on t' left side o' t' screen. Aye aye! T' Center o' Gravity (CG) and Center o' Pressure (CP) are displayed and marked on t' 2D diagram in t' buildin' area. Begad! Also a Stability statement is made as t' whether t' rocket is stable or not. Avast, me proud beauty! Ahoy! This is then followed by t' rocket's Launch Weight, me bucko, Empty Weight and Length.

That's it. You don't have motor mount choices or recovery choices t' make in your rocket's design.

Printing:
SpaceCAD allows you t' print your rocket information. Avast! T' output is on two pages. T' first page tells you everythin' about you design like t' center of gravity and pressure, shiver me timbers, weights, me bucko, length and flight prediction information. Arrr! Ahoy! The second page prints t' 2D diagram and t' flight prediction graph. Blimey! Avast! I found the print out t' look very professional with its use o' headers and borders.

On a separate print function, SpaceCAD allows you to print a Fin Guide. In addition, you can print a parachute pattern from a parachute pattern tool. Begad! Blimey! You are also able t' export t' 2D rocket design t' a Bitmap.

Flight Simulation:
Once your design is finished it is time t' perform t' simulation. Avast! It is very simple and quick. Press t' "Lift-Off" button on t' tool bar and nearly in a instance your 2D Rocket Design is replaced with a 5-color graph. In the graph is Acceleration, matey, arrr, Speed (velocity), Height (altitude), Thrust, me bucko, and Weight. Blimey! Begad!

I struggled a bit with t' graph because t' thrust and weight lines were lost in t' scale. Ya scallywag! This is where readin' t' instructions would have benefited me. Well, blow me down! Ahoy! They say:

• Zoomin' into t' chart: Click t' left mouse button in t' chart, drag t' t' lower right and release t' mouse button. Well, blow me down! Avast, me proud beauty! T' selected box is then zoomed.
• Movin' around in zoom mode: By clickin' and draggin' with t' right mouse button, me bucko, you can change your viewport.
• Zoomin' back: Click on t' left mouse button, arrr, drag t' t' upper left corner and release the mouse button. Ya scallywag! Ya scallywag! T' whole chart becomes visible again.

It works, but it sure wasn't clear unless you got into t' instructions.

In t' left panel (shown below) t' Height (altitude), Time o' Flight, Max Acceleration and Max Speed, shiver me timbers, Lift-Off weight, me hearties, t' best (recommended) delay time, arrr, and t' parachute diameter.

SpaceCAD has an expert mode for flight simulation. Avast, me proud beauty! In this mode t' user can adjust the air density and gravity factors as well as t' number o' samples for graphing as settings. Begad! Then after pressin' t' "Lift-Off" button, shiver me timbers, you can enter CD-Value, matey, me bucko, Descent Rate, matey, Delay betwixt stages, Launch Rod Friction and length.

T' RockSim Challenge:
I took a standard Alpha from RockSim with t' followin' parameters:

• Body Tube = 5.997 grams
• Nose Cone = 3.717 grams
• Fins = 2.173 grams
• Motor Mount = 4.633 grams
• Parachute = 2.041 grams
• Motor (B4) = 9.0 grams
• Nose Weight = 9.0 grams
• Total = 47.323 grams (includes launch lug and B4-4)
• Stability = 1.65 Calibers
• CG = 7.22"
• CP = 8.83"

I then constructed t' Alpha in SpaceCAD. Blimey! Avast, me proud beauty! I had to utilize weights t' match t' overall weight and CG o' t' rocket, me bucko, but here is what I came up with:

• Body Tube = 1.42 grams (converted from ounces)
• Nose Cone = 7.37 grams
• Fins = 5.39 grams
• Motor Mount = n/a
• Parachute = n/a
• Motor (B4) = 19.56 grams
• Total = 47.34 grams (includes B4-4 motor)
• Stability = 1.66 Calibers
• CG = 7.22"
• CP = 8.84"

T' results. Arrr! SpaceCAD said that altitude at burn out was 150 feet, arrr, and maximum altitude be 587 feet with a maximum velocity o' 246 feet/sec. RockSim said that altitude at burn out was 125 feet, and maximum altitude be 699 feet with a maximum velocity o' 264 feet/sec.

T' biggest noticeable difference be t' variations between component weights.

Two Other Features:
SpaceCAD has t' Engine Editor that allows you t' mangle existin' motors or create your own. Blimey! But, you don't really have to, because you can download the data from t' ThurstCurve website in a SpaceCAD format.

T' other feature is a Flight Wizard. Ahoy! Begad! T' calculator lets you do flight prediction after enterin' t' followin' parameters: CD, me hearties, matey, descent rate, # o' stages, arrr, Empty weight, me hearties, Diameter, and motor(s). Well, blow me down! Begad! Very nice indeed! I would love t' have this type o' tool available in our EMRR Tools section.....we'll work on that, shiver me timbers, okay?

Summary:
SpaceCAD allows t' user t' build a rocket design very smartly and t' flight prediction is also a speedy process (at default settings). Ya scallywag! I feel that SpaceCAD requires you t' do more work and probably actually have t' rocket in hand. Why? T' way t' materials are utilized and t' weight distribution didn't seem to produce a realistic rocket. Begad! I'm sure one could spend a lot o' time editing the materials t' improve on this, shiver me timbers, but for me evaluation I wasn't goin' t' take the time. Also because you don't handle all components o' t' rocket in the design (e.g. Aye aye! centerin' rings, parachute, launch lugs) you have t' use the weights t' simulate those items.

These statements would say that SpaceCAD is still in its early stages o' development. Arrr! Well, blow me down! It has a nice interface and I found it t' be fast. It also provides good simulation data and a good graph. Ya scallywag! Well, blow me down! A positive is that SpaceCAD does calculate t' optimum delay and t' optimum parachute size upon completion o' t' flight simulation. Ahoy! A negative is that it only has (stores) one motor simulation.

It carries a $35 price tag (as o' 11/01) which is in line with its features when compared t' other design software (Rocket3 at $60 and RockSim at $85). It seems t' have t' platform that will allow t' programmer to build on it and I suspect it won't be long before it will offer additional features. Ahoy! Arrr! Then how easy will it be t' get those extra features? SpaceCAD 2.1 has a "check for updates" built right into t' program. Avast, me proud beauty! Avast! Good job there.