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Heavenly Hobbies H.H. SIMIT v1.2 Rocket Flight Simulation Software

Heavenly Hobbies’ H.H Simit(tm) (v1.2) is a computer-based flight simulation software for model rockets. Using advanced numerical methods, it calculates altitude, vertical velocity and acceleration throughout model’s flight, sampling flight conditions 10 times per second.

How does it work?

Let's say you have a model rocket at home and you need to find how high it will go and how long it will take to return back to Earth. With H.H. Simit, you choose an engine from the pre-populated database, you input your rocket's characteristics (e.g., weight, diameter, etc.), then you sit back and let H.H. Simit calculate all the flight information for you!

Input Screen

Future rocket or engine modifications will not be a problem as the information database is user-editable. You don’t need to buy a new version of H.H. Simit(tm) to simulate the flight of a new model rocket or to accommodate the thrust characteristics of a new engine! This flexibility is integral part of the software’s design.

Is it reliable?

Absolutely! We use tried-and-true calculation methods and NASA-based atmospheric models to bring you simulation results comparable with the most popular commercial model rocket simulators in the market. You can find an independent review of our product at

Output Screen

How come H.H. Simit is so inexpensive?

We are able to offer powerful software at the lowest price around by cutting out the most programming-intensive portion of the software code. That is, we exclude the software code that generates a drawing of your model and calculates CG vs CP (stability relationships). This code is included in the more expensive design and simulation programs, like SpaceCAD and RocSim. It is also dependent on the geometry of the components used to build the rockets (as well as the materials used) so this part constantly needs updating. This is the main reason why the big-name software keeps getting more expensive every year.

If you need a computer-aided design tool, that is, one that draws a virtual model rocket and tests for stability, go ahead and purchase a copy of SpaceCAD or RocSim. They are excellent products. However, if you are building commercially-sold kits from a responsible manufacturer, your kit will have been tested for stability by the manufacturer as part of the design process. In that case, don't waste your money! H.H. Simit is all you need!!*

Skill level: 2


. Pentium III processor, running at 533Mhz

. 256 Mb RAM

. 1 Gb Hard Disk Space

. 800 x 600 resolution display, showing 16 bit color

. Microsoft Windows XP

. Microsoft Excel 2000

. Microsoft Word 2000

*You can check any model rocket for stability by using the old-fashioned "swing test". This is done via the following procedure:

--First: Prepare the rocket for flight. It should be fully loaded with engine, recovery system, wadding, etc.

--Second: Tie a cord around the rocket at its center of gravity (balance point).

--Third: Holding the model by the cord, swing the rocket round you, in circles. Observe if the rocket remains oriented, with the nosecone pointing in the direction of motion (againt the wind). If so, it is stable as tested.

--Fourth: If the model is not stable, add weight to the nosecone and retest.

Give it some air!
Altimeter Pod.

Add a personalized card!
Hand-written greeting card.

Availability: Usually ships in 2-3 business days


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