Hello All,

British space modeler Stuart Lodge gave me a "heads-up" about an article on two different types of finless rocket passive stabilization techniques--one of them even permits finless models to take off stably with *NO* launch rod or rail! (The author included a photograph of a Polaris A-1 scale model that does this.) Another good feature of both types of finless rocket is that they produce realistic, wide smoke trails, just like full-scale rockets. Below is a link to the article: "Finless Rockets Using Engine-Driven Gas-Dynamic Stabilization" by M. Dean Black (Apogee Components Peak of Flight newsletter, Issue #379, December 2, 2014): http://www.apogeerockets.com/educat...wsletter379.pdf Now:

Having read Mr. Black's article on finless rockets, I think I may have a simple solution--one that wouldn't mar a finless scale model's appearance--to one problem that these rockets have. He wrote that both types of finless rocket cease to point into the wind after the motor ceases thrusting, which requires either spin stabilization (which can be tricky to implement) or small regular fins at the rear, in order to make the rockets fly straight while coasting. Well:

I'm sure you all have seen the flush (even with the body surface, that is) NACA inlets (see: http://en.wikipedia.org/wiki/NACA_duct ) on aircraft and/or high-performance automobiles. If multiple NACA inlets were used in a finless rocket, spaced equidistantly around the body tube (either at/near the model's CG [Center of Gravity] or near the rear of the model), they might give the rocket positive static stability during unpowered coasting flight as well as during powered flight. Because they are diffuser-type inlets (like subsonic and supersonic ramjet inlets, which widen aft of the forward opening), they create low pressure inside them, which draws external air into them. It is this trait of the NACA inlet that, I think, would make a finless rocket that was equipped with them self-stabilizing even while coasting; if the model was deflected from its direction of flight, the asymmetrical forces generated by the NACA inlets (those on the lee side of the rocket would be "choked" for air, while those on the windward side would have excessively high pressure) should swing the rocket back into its original orientation. Also:

A U.S. Air Force ATIC (Air Technical Intelligence Center) report (I've reproduced it below) specifically mentioned using "flow control slots" (the NACA inlet is a type of flow control slot) on wingless and finless aircraft to provide stability. The report dealt with a famous 1948 UFO case, but at the time, it was regarded as a possible foreign (rather than extraterrestrial) vehicle. Here it is:

Below is technical information on how *finless* rockets can be made aerodynamically stable. This same information also enables such vehicles to fly horizontally (with a different CG/CP relationship that that required for rockets, of course), supporting themselves via aerodynamic lift. This information, which comes from the Prandtl theory of aerodynamic lift, was used in an ATIC (Air Technical Intelligence Center) analysis of, of all things, a 1948 UFO sighting! (Back in those days, UFOs were suspected of being foreign--probably Soviet--manned or unmanned reconnaissance aircraft. Two Eastern Airlines pilots, Chiles and Whitted, saw a wingless, torpedo-shaped object pass their airliner (see: http://en.wikipedia.org/wiki/Chiles...d_UFO_encounter [this article contains additional links] and https://www.google.com/images?q=Chi...AQ&ved=0CB8QsAQ ), and the ATIC analysis indicated how such an object, if it were an aircraft, could fly stably and produce lift without wings or fins. This information would be a boon to flying scale models of finless missiles and space launch vehicles, as they could fly stably without clear plastic fins--or fins of any kind! Below is the information:
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The following is from pages 36 – 41 of UFO’s, Past, Present & Future by Robert Emenegger (Published 1974 by Ballantine Books, New York, NY; book adapted by Sandler Institutional Films from an original 1974 screenplay by Robert Emenegger)

Tech Intelligence Div.

Intelligence Department

Wright-Patterson AFB, Dayton, Ohio



Report 102-122-79



Apparently it is not of domestic origin since a thorough check of 225 flight schedules, both commercial and governmental, revealed that in only one instance did the reported flight paths cross. (See chart enclosed as Exhibit “I”). This single exception was the flight in a northwesterly direction of a C-47 enroute Robins AF Base to Olmstead Field, Pa. [Pennsylvania]. Its time of departure would have enabled it to have passed through the approximate areas on the 24 July 1948 where the sightings were reported. However, the factors of speed, direction of flight, maneuvers, configurations, lights and other factors rule out this one possibility.



Objects similar in configuration have been reported as follows:



a. Rocket-like objects capable of immense speed were seen during the past summer in broad daylight in Denmark, Norway and Sweden.



b. A wingless aircraft was observed moving at high speed in Obrechstreet, Arnheim, The Hague, Holland. The object was seen intermittently through clouds and was reported to have two decks.



Flying Fuselages (Torpedo or Cigar-Shaped Body)



a. While the cigar or torpedo-shaped body represents an efficient form for the fuselage of an airplane or the body of a guided missile, in neither case has it been used as a primary lift producing surface. However, an extension of the Prandtl theory of lift indicates that a fuselage of the dimensions reported by the Eastern Airlines pilots Whitted and Chiles in the Montgomery, Alabama, incident could support a gross weight of approximately 12,000 pounds at an arbitrarily chosen stalling speed of 150 miles per hour, conservatively estimated. The Prandtl theory probably gives very conservative values of maximum lift for bodies of this shape. If a lift coefficient twice as great were used (such a value has been given by a German scientist from memory of his wind tunnel researches in Germany), a gross weight of 24,000 pounds could be supported at the assumed stalling speed.



b. Although the craft sighted by Whitted and Chiles was reported to be without wings or fins, it is possible it could have been equipped with extensible wings for take-off and landing, contained within the fuselage. In such a case a wing span of nearly 90 feet would be possible. If an aspect ratio of 5 were used (18 ft. mean aerodynamic chord), and if the wing design incorporated slots and flaps, the wing could support 115,000 pounds at a stalling speed of 150 mph. It is possible that the fuselage could also contribute lift with this arrangement, depending upon the incidence of the wing. This type of aircraft could also be partially supported in the take-off and landing condition by the vertical component of the jet thrust, if the landing and take-off took place with the fuselage axis, or the jet stream direction in a vertical or nearly vertical attitude. The further possibility that an extensible rotor, concealed within the fuselage, could have been used, would provide another method for landing and take-off that would allow wingless flight at very high speed. Such a design could result in a relatively large duration of flight and corresponding range.



c. While no stabilizing fins were apparent on the “flying fuselage” reported by Whitted and Chiles, it is possible that vanes within the jet, operated by a gyroservo system could have provided static stability, longitudinally, directionally and laterally. The same vanes could also have been used for accomplishing static balance or trim, as well as control for maneuvering. A square-tailed body of the type reported with the center of gravity sufficiently far forward can develop, approximately, a neutral stability and the possibility exists that definite static stability could be produced by a judicious use of flow-control slots located somewhere along the fuselage.

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That obviously doesn’t explain the UFO, but it shows us something other than a cavalier attitude toward the UFO problem. The Air Force was doing some serious thinking.


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I hope this material will be helpful.

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Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
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