| 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. |
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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.
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.
NOSECONE 32 replaces both NOSECONE for Windows and NOSECONE for DOS.
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.
| Density Units | Competition Balsa | Hard Balsa |
|---|---|---|
| lb./cu.ft | 8 | 15 |
| oz./cu.in | 0.0741 | 0.139 |
| g./cu.cm | 0.128 | 0.24 |
| oz./cu.cm | 0.00452 | 0.00848 |
| g./cu.in. | 2.1 | 3.94 |
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).
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:
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 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.
The volume V is given by:
where l is the length of the solid, d is its base diameter, and its defining radius R is given by:
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.
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.
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>
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.
Mark Fisher
microzen@hotmail.com
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