Kites for Lifting Antennas

The Weather Service both in the US and abroad, made extensive use of kites for lofting weather instruments in the period from 1880 to 1920. Also kites were tested for man lifting in the same period, for applications like military observer. What was accomplished was just remarkable.

Versions of the winged box kite was the champion in all cases. But that was before the unspared, parafoil kites we have today were invented. The standard was a box kite called the Blue Hill Meterological Box Kite. It had a rectangular section when viewed from the front.

Today, there are special kite stores, so one is not limited to what you can build from plans in books, or the cheap paper diamond kites sold in toy stores. Any good kite store will be loaded with the fancy, and expensive aerobatic kites, but they should also have excellent load lifters, if you know what to ask for and look in the dustier corners:

  1. The Classic Box Kite. This was a standard, considered by some hard to fly. Multicell box kites are complex to build, but work well. Some of the variations include a tetrahydron shaped box kite, but it is mostly good looking, not a good lifter like the classic box kite.
  2. The Winged Box Kites. Probably the best of the rigid kites. The triangular winged box kite is a great lifter. The French Military Kite, is a classic. Dihedral wings on box kites add to stability and lift. One of the most famous man lifting kites was a several-celled box kite with small wings, the Cody Manlifter. [No, that is not Buffalo Bill Cody, but a person often confused with him, Sam Cody, an early kite/aeroplane pioneer.]. You can even purchase modern versions of the Cody Manlifter in several small sizes. It is an excellent design.
  3. The Parafoil. A commercial company makes four sizes usually available. The sizes are rated in square feet of area and go from pocket size to a bit less than four feet wide and a bit less than five feet from front to back. They are attractive because they fly at higher string angles than the box kites, more vertical. They pull like a deamon, with the largest size recommending 250 pound test flight chord. They wad up into a stuff sack that is very easy to transport, since they have no sticks or spars.
  4. The Sleds. In its simpliest form the sled is a flat piece of cloth tied at the right and left side to the bridal, with two spars running from front to back to hold it rigid in one axis only.

The parafoil along with the sleds have a disadvantage in gusty winds. They will collapse in the air and fall like a rock, all the way to the ground if they do not reinflate in time. The rigid kites are far more immune to gusty winds. But they have spars etc, that make them harder to pack, and heavier. Some of the kites of the 1890's had so many spars, cells, cross supports, braces, etc. that they were as complex as the early aircraft. The Cody Manlifter was very picky about having the fabric tight, thus having curved edges.

The Scott Sled and its variants is a good stable kite that is spared in one direction only, front to back. The Allison Sled is a variant of it. Various versions add vents in assorted patterns which are alleged to increase stability and tolerance for wind variations. For wind measurements I have flown simple tethered sleds in the trade winds for weeks at a time. Our record was nine days that a sled stayed up, staked to the ground, day and night, through land breeze/sea breeze transitions, with no intervention. It was finally collapsed and knocked down by a nasty gusty roller of air. It took seconds to shake it open and relaunch it.

Other kites that are useful as lifters include double triangular winged box kites, Coynes, and even the Malay kite which is the stock diamond shaped kite just about everyone bought at the toy store as a kid and played with. A Malay is certainly easy to build and will loft a small antenna wire, but it is unstable without a drag producing tail, at least when compared to things like winged box kites and parafoils.

One person has made a study of sewing a type of vented sled kite that is kind of a cross between a Scott Sled and a Parafoil. He has flown some very large ones which he has made and used them to do heavy lifting, and launch a squadron of parachuting stuffed bears.

The U.S. Weather Service standardized on the "French Military Kite", a triangular winged box kite. The kite is like a classic box kite, but only with three sides to the box instead of four. It also has dihedraled wings added to one surface which greatly increases its side to side stability. The Weather Service flew trains of these kites to increase lift and stability since they sampled air at multiple levels, much like space diversity receiving. One such train of kites was flown to 27,000 feet! The pull was so great that these trains of large kites were flow on piano wire, a very dangerous practice for the amateur. The Blue Hill Box Kite was another weather bureau standard. It was a large box kite with a rectangular cross section cells about three times as wide as they were high, but otherwise similar to the standard two cell box kite. It had one fore cell and one aft cell with fore/aft spars holding the two cells in alighnment.

On the top of Mauna Kea (13,380 feet) I have flown a small sled through two changes of wind direction and been able to look up and see the kite string make a full spiral above my head as it rose the several thousand feet to the kite itself. The string was very small, but Kevlar with an incredible breaking strength that would slice off fingers before it broke. One weather service report from the 1920's reports a train of kites that made nine revolutions of a spiral as it ascended above an observer through multiple changes of wind directions.

You should not use the antenna wire as "kite string", but support the kite with a flying string and parallel or hang the antenna structure from the flying string. A kite carrying away in a wind with a trailing antenna wire is a dangerous situation. You should make sure that if the kite breaks free, it cannot take the antenna wire with it. One way of helping to insure this, is to use a stouter cord below and through the antenna bearing section, and a lighter cord above, so if the kite carries way, it is more likely to break off above the antenna section.

Big Kite + Stiff Trades = Major Tension

One last word of warning. If you get a decent large kite, like a six foot triangular box kite or a big size 15 Parafoil, get some serious kite cord, something well over 125 pounds. Also purchase some heavy duty leather gloves with wrist protection flanges on them, like gauntlets. Do not underestimate the potential dangers of flying a large kite in any kind of wind.

These big kites are renouned as lifters for a reason. A large kite needs preparation before launching into any wind regime. A modern ripstop nylon kite in a large size is NOT the toy paper dimestore kite of your youth, flown with cheap cotton twine.

A toy paper kite will tear up in too much wind. The flimsy cotton string used will break easily and is not prone to rope burns, slicing wrists to the bone or popping off fingers at the joints. The flimsy spars of the dimestore kite will snap easily if overstressed. Thus it is relatively safe to fly such a kite.

A kite made of ripstop nylon, carbon filament spars and flown with heavy duty nylon cord is a very different item that must be respected.

The first time you try to hang onto a large parafoil in a stiff 30 mph wind, you will know what I am talking about! Rope burns can happen quickly and cut to the bone or worse. Hand protection is mandatory. Rope burns are terrible. The skin and muscle are "erased" away leaving a deep trench that is slow to heal and very, very painful.

It is well worthwhile to invest in a small parafoil or winged box kite suitable for 40 or 50 pound line and test fly it to get a feel for heavy duty kites. Remember, a kite twice as large is going to have a pull four times as great or more. Also pull goes up with the cube of the wind speed!

The large military kites were flown from special trucks that carried large drum wenches. These kites were only about three times larger than kites easily available at kite stores today and routinely lofted observers to several hundred feet in WWI.

An interesting "target kite" was used in WWII that had a metal rudder on a 10 foot tall Malay type kite with a black aircraft silhouette painted on it. It was towed behind a jeep with an "operator" in the back who used a pair of control lines to manipulate the rudder on the kite. The jeep would go around an oval course while 50 caliber machine gun trainees would blast away at the kite above.

A friend had one of these and we would fly it in Oklahoma from the ground using a 4x4 inch oak wood beam, 6 feet long, as a flight handle. We would stand behind a telephone pole and let the pole take the strain of the kite on the 4x4 handle and still be able to loop the kite and steer it by rocking the 4x4 back and forth behind the pole. It was impressive to see the divot ground into the 4x4 where it was bearing against the telephone pole.

One report of an experiment with 160 meters raised several interesting points. The objective was to fly a kite next to the ocean and use the Pacific Ocean as a ground plane. It worked extremely well but had two major problems.

1. It picked up literally volts of signal from the local high power AM broadcast stations, blotting out the front end of the receiver. Clearly, unless you are quite far from such a broadcast site or sites, you need to have a carefully built filter box. Probably bandpass with the major rolloff being on the low side of 1.8 Mhz. Possibly even a tunable notch section in the middle as well. Of course the usual static grounding of wind generated static electricity is essential. Any kite antenna MUST have a path to ground. A choke or a high value carbon resistor should work. In the case of a 160 meter antenna, the AM broadcast blocking filter could easily be designed to have as its first component something to provide a DC path to ground.

2. A kite that has fallen into the ocean is a monster sea anchor. Rip tide can make a kite impossible to retrieve. Kites have been built with collapsible harnesses. This is probably a great idea. Basically one examines the harness that holds the kite in the right aspect to the wind stream. Find a critical part that sets the angle of attack. Make this with a link of much weaker string than the rest of the harness and the flight line. Thus a abusively strong yank on the flight chord will break the harness causing the kite to flatten out and stream. Such a harness modification would have made it possible to retrieve the kite in the ocean. Since fancy lifting kites can cost a hundred dollars of more, getting the kite back is a priority.

Finally, consider a 1/4 scale model designed for 40 meters. It will solve a lot of problems and give a lot of experience at much less expense and hazard. Anything for 160 meters is just plain BIG.

One last word, if the kite is big or flow high, you can get into trouble with the Federal Aviation Administration. Here is a sample peek at typical FAA regulations. For most up to date information you should check the FAA's own web pages:

FAA Part 101

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