NOSECONE 32
NEW VERSION

NOSECONE has been updated to NOSECONE 32, now fully compatible with Windows 95/98 and Windows NT 4.0. This is a beta release, and you can still download the Window 3.1 and DOS versions. When NOSECONE 32 is fully released, these versions will be discontinued.

License and Limitation of Liability

This program is provided as is, with no warranty of any kind, including, but not limited to, any guarantee of fitness for a particular purpose. The author, his agents and assigns, assume no liability for any losses users may incur by using this program or relying upon its results. Users are specifically warned that this program's results are un-verified, and should not be relied upon for accuracy of design.

The author is not associated with Balsa Machining Services (BMS) or Impulse Aerospace in any way. Designs generated by this software are not guaranteed to be producible by that company (or any other), nor is BMS required to conform to the values created by this program. BMS has not been consulted about the content of this software, and is not responsible for it or its results in any way. Do not contact BMS regarding this software, its operation or limitations. This is an independent effort that relies on industry standards, to which BMS contributes.

This program is freeware. You can distribute it freely, provided 1) you don't charge for it or the media it comes on, and 2) you distribute the entire archive, unaltered either by addition, modification or deletion. Author retains all rights, including, but not limited to, copyright, right of sale, modification or advertisement. This archive may NOT be included in any collection for which money is charged, regardless of intent, costs incurred or level of profit. You may not reverse engineer this program in any way. If any of these restrictions are violated, author may seek any and all remedies available to him at law, and violator will be responsible for all costs, charges, fees or other debts so incurred. By using or distributing this software, you agree to be bound by all terms and limitations set forth in this license.

Purpose

NOSECONE is designed to give masses and centers of gravity (mass distances) for solid nose cones turned from balsa or bass wood. It assumes a uniform density, and is therefore not applicable to hollow bodies or units made from more than one material.

NOSECONE is designed to dovetail Balsa Machining Services (BMS) semi-custom nose cones with Visual Center of Pressure (VCP) from Impulse Aerospace. It is primarily intended for the model rocketeer, though others may find it useful, and are invited to send their comments to the author.

Requirements

NOSECONE requires the Windows 95/98 or NT 4.0 operating system, and a display resolution of 800x600 or better.

NOSECONE 32 replaces both NOSECONE for Windows and NOSECONE for DOS.

Known Bugs

Parabola solids are not accurately represented in the graphic, they are estimated by a tangent ellipse. Values calculated by NOSECONE for this shape are for parabola.

Tangent Ogives with a Length to Diameter ratio greater than ten (10) are often drawn incorrectly. In Windows NT the tips are drawn poorly, and under Windows 95/98 they aren't drawn at all. This is a bug in the Windows Arc API, and not in NOSECONE.

Revision History

0.9.0

Beta, Print not implemented.

0.9.1

Beta, Print still not implemented, added better small icon, fixed no confirm on Exit, added Print Form, added support for associated .ncn files, automatic association of .ncn files by program, and 95/98 graphics bugs.

Operation

Program Appearance

Entering the Density

NOSECONE is unitless, i.e., it does not keep track of units nor convert entries in differing units to a common base. You are responsible for entering all data in a common set of units for mass and length. BMS's catalog gives the density of their materials in pounds per cubic feet (lb./cu.ft.), but this is rarely helpful for the model rocketeer, who most often works in grams or ounces per cubic inch or cubic centimeter. Below is a table converting the BMS densities to other unit bases:

Density
Units
Competition
Balsa
Hard
Balsa
lb./cu.ft815
oz./cu.in0.07410.139
g./cu.cm0.1280.24
oz./cu.cm0.004520.00848
g./cu.in.2.13.94

Determine which units you'll be working in, and enter the appropriate value from the table above in the Density field.

Note that these are the maximum densities you'll see in the finished parts you receive from BMS, the material used to make your part will probably be less dense. It has been the author's experience that, on average, Competition Balsa is more often ~4 lb./cu.ft (~0.037 oz./cu.in or ~0.064 g./cu.cm), and Hard Balsa is more often ~10 lb./cu.ft (~0.093 oz./cu.in or ~0.16 g./cu.cm).

Entering Shape Descriptions

Designs are built from left to right, the top-most entry row representing the left-most shape. The left-most shape of all designs must be a Cylinder, and NOSECONE will not permit any other type to be selected for this shape. Enter the Cylinder's Diameter and Length in the fields provided. You may also enter a Bore diameter if you wish. When NOSECONE has computed a Mass and CG for this shape, it will enable the next Shape selection box in the row below.

Shapes consist of four measurements, the base (left) Diameter, the overall Length, and possibly a Bore and a Frustum or tip (right) diameter. Conical shapes can have both a Bore and a Frustum, and Cylinders can have a Bore (NOSECONE automatically sets the Frustum of a Cylinder to its base Diameter), but Parabola and Tangent Ogive shapes can have neither. Specifying a shape that does not (or shape type that cannot) have a Frustum prevents the next Shape selection box from being enabled.

Bore and Frustum values cannot be greater than the Diameter. Tangent Ogive and Parabola shapes cannot have a Diameter greater than twice their Length. NOSECONE will warn you if you violate these restrictions and adjust you data to conform to them.

NOTE: Despite the restrictions stated above, it is possible for NOSECONE to generate designs that are not available from BMS's Semi-Custom catalog. Consult their catalog, which is available on their web-site:

http://user.mc.net/~bms/

Once your design is complete, pressing the Render Graphic button will cause NOSECONE to display a graphic representation of your design in the large box below the data entry fields. See The Graphic for more information. You can use the File Menu to save it in a NOSECONE Design File, clear the current data entries and graphic, and print your results. You can use the Options Menu to change the colors used to render the graphic and switch between the Tangent Ogive Empirical Method and Approximation Method of calculation.

The Graphic

The image created by NOSECONE when the Render Graphic button is pressed represents a plan view of the design and includes the locations of the center of gravity for each individual shape and the overall design. CGs for each solid are represented by a circle, and the center of gravity for the entire design is represented by a circle with cross hairs. Bores are represented with a dashed line. Below is an example graphic showing a four shape design.

Example Graphic

The left-most cylinder has a bore, and is followed by a conical shape, another cylinder and finally a Tangent Ogive shape. The center of gravity for the entire design is somewhere near the base of the conical shape.

NOTE: The example design is not found in BMS's Semi-Custom catalog.

The graphic can be copied to the clipboard for inclusion in other graphics programs by double clicking on the image.

NOTE: There are some known bugs in the graphic rendering. See the Known Bugs section in About NOSECONE for more details.

Tangent Ogive Empirical Method

The Empirical method used by NOSECONE to calculate the mass and center of gravity of Tangent Ogive shapes is from Appendix A of Missile Configuration Design by S.S.Chin, which supplies the following formulae:

The volume V is given by:

Volume Equation

where l is the length of the solid, d is its base diameter, and its defining radius R is given by:

Radius Equation

The center of gravity of the shape is then determined by interval halving.

A quick examination of the formulae will show that the magnitude of the values it uses could often exceed the capabilities of the personal computer processor, resulting in a loss of precision. Every effort has been made in the implementation of this method for NOSECONE to forestall the onset of these failures, but nothing can prevent it entirely. Therefore, NOSECONE provides an alternate method of handling Tangent Ogives, the Approximation Method.

Tangent Ogive Approximation Method

The Approximation method for determining the mass and center of gravity for Tangent Ogive shapes is based on a calculus method of integration. Slices of the object are taken at regular intervals and their volumes approximated as cylinders:

Approximation Method

The volumes are then summed to determine the approximate total volume of the solid. This value is then halved, and the slice containing this amount is determined. The center of gravity is then linearly interpolated.

NOSECONE uses 1,000 slices so the result is as accurate as possible without adversely affecting speed. Needless to say, this method is not perfect, but is useful when the Empirical Method fails.

NOSECONE Design File

NOSECONE design files have an extension of .ncn, though the program can open and save files with any extension. If an extension is not supplied, the default .ncn extension is appended.

Design files contain the current shape design and selected options, are text-based, and have the following format:

<density>,<estimate flag>,<fore color>,<back color>
<shape type>,<diameter>,<length>,<bore>,<frustum>
<shape type>,<diameter>,<length>,<bore>,<frustum>
<shape type>,<diameter>,<length>,<bore>,<frustum>
<shape type>,<diameter>,<length>,<bore>,<frustum>

The second though fifth lines contain the information for each shape. All the fields are positive floating point numbers of double precision, with the exception of the following:

The first shape type is always 1 (cylinder). Even if a shape is not defined, it is included in the file, along with any data in its disabled fields.

Credits

The author thanks BMS for its fine work and dedication to the model rocket building community.

Thanks to Peter Alway, who, in his fabulous book Retro Rockets, published by Saturn Press, clued the author to the existence of BMS in the first place.

Formulae used to determine the data given by NOSECONE are primarily from Machinery's Handbook, 17th Edition by Oberg & Jones, published by Industrial Press, Inc., though they can be found in most any basic mechanics text or reference. Notable by its absence is the Tangent Ogive solid, which was solved with formulae found in Missile Configuration Design by S.S.Chin published by McGraw-Hill, and the assistance of Gary Crowell, Sr., author of the indispensable program Visual Center of Pressure (VCP) available from Impulse Aerospace.

Contact The Author

I'm anxious to hear if you find this program useful and eager to learn of any bugs or errors you find. I'd also enjoy hearing about any enhancements you'd like (including other solids and their formulae) and other operating systems you'd like to see supported.

Mark Fisher
microzen@hotmail.com


Download

Download the current version of NOSECONE 32 in ZIP or self-extracting ZIP format.

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