Aircraft Arresting Barriers

Spidernet

Spidernet Portable Vehicle Arresting System is a unique and powerful means to safely arrests moving vehicles on control sites and such

Key features of the Spidernet system are:

- Designed to safely arrest land vehicles up to 150 km/h or 90 mph, variable capacity versions (weight / speed)
- Unique safety features: the net construction holds the vehicle securely and the unique Spider-System stabilizes the motion of the vehicle to be stopped
- Designed as a truly portable system: one or two men to carry, to set up, to operate and after use to put back into package, fits into car trunk, minimum maintenance
- various anchoring choices: between cars, roadside railings, or with extra accessories to concrete, even to soil with limitations
- various versions: net reaches over 2 or 4 lane widths, basic masts or spring loaded masts, which can be released with rope or electric push button
- use for example at control sites and such, police or military. Two videos of live tests are here, one with inside camera recording too.

The story of the SPIDERNET started in the 1988, when the local Nurmijärvi County Police Chief Mr. Matti Ahdeoja had a discussion with Mr. Uotila. Chief Ahdeoja heard about those arresting barrier systems, which are used to safely stop military jet aircraft in emercency. He asked, if not simply the same principle could be applied to stop fleeing cars, because it is a major problem, for which the police had not any safe solution. A short calculation showed, that the necessary basic parts, ie. the net and textile brakes, would weigh only about 30 kg when downscaled from the corresponding aircraft arresting system.

After this exciting discussion the differences between car arresting and aircraft arresting situations we studied and some new and unique solutions were found. Consultations with the local Nurmijärvi Police Inspector Markku Tuominen and Chief Ahdeoja were extremely useful in the final design. As a result, the Spidernet can be used in everyday police work without complications.

Later, an U.S. Patent no 5,310,277 was granted for these new inventions. The problems of arresting safely a land vehicle (car and such) were solved with the two patented features, namely

1. The diamond shaped and vehicle wheel sized net construction,

to keep the net safely attached to the front of the car and to simultaneously block the vehicle immovable after arrest, see especially Figures 8 and 10 of the patent. This form differs amazingly from the aircraft arresting net. The reason for the difference is, as simple it may sound, that the car does not have wings or a sleek nose or relatively small main wheels far back, but in the contrary a flat front and large rough wheels in the heavy front section.



2. The Spider-System, or the X-formed arrangement of the braking devices,

to absorb the vehicles momentum (advance movement) in a safe and stable manner, see below the Fig. 7 of the patent text. The sequence shows characteristically different phases of the vehicle arrest. The first (top) figure presents how the system is set up for arresting the vehicle. Anchor cars are aside the net. Road side railings and other fixed structures apply for anchoring as well. The mast units can even be bolted to concrete or with limitations, to soil. The brake elements 4 and 5 absorb the vehicles momentum. The element pair 4 are operative for the initial phase only. The main, or cross-connected brake element pair 5 become under tension and operative only after the vehicle has advanced a certain distance. Before the main elements 5 start to operate, the initial elements 4 become inoperative. The X-formed arrangement makes possible high speed (longer stopping distance) arrests, because the vehicles path stays stable and the driver cannot affect it.

According to these guidelines, the first trial systems were built and tested with care. In tests the Spider-System showed good stability and no tendency to a curved path. Finally thelimit performance tests verified these unique SPIDERNET features functional up to about 150 km/h or 90 mph.

The 2-lanes wide net, the braking units and the simple masts did weigh slightly above 30 kg. This complete system was capable to arrest a 1 ton vehicle upto a 150 km/h speed, or to absorb a vehicle momentum of 1 Megajoule ( 1 MJ). The package was designed to fit into a car trunk. Below is this basic system package, having dimensions of about 1 m x 30 cm x 30 cm or 40 in x 12 in x 12 in. The included accessories facilitate setup of the system between road side railings, for example.

basic unitset_up_between_railings

The SPIDERNET is designed for anchoring also between vehicles or road side railings. Below SPIDERNET is anchored betwen two Austrian police vehicles during a test in Wien, Austria. Mr Uotila drives while an Austrian Police Colonel Stifter is riding on the back seat. The entry speed was 100 km/h. The full stop took place after 30 meters, which is much less than ever attainable with the regular brakes of the vehicle itself. Naturally, the vehicle brakes are never applied during demonstrative tests. (Those tests where the brakes were intentionally applied, showed only an exceptionally short stopping distance but no other irregularities.)

SPIDERNET in Austria

Below is a photo after a test of 140 km/h. The net blockage of the front wheels is so strong, that the vehicle is not even able to back up that short distance required to release the tension in the net. The driver Mr. Uotila is here literally "nicked" by his own creation. The arrested vehicles remains mostly intact. The car chassis can get some dents and scratches from the textile net. The front wheels get tangled so heavily with the net, that in most cases the vehicle is blocked immovable after arrest.

nicked

Below is a link to a video of a similar test, which video shows both outside and inside recordings of a test at 100 km/h. The outside recording shows how the special front wheel blocking feature of the SPIDERNET takes place already during the stop, after some 5 meters from the net line. On the video you can really feel the excitement of intentionally driving against the net and the emotion of recovering intact from it. If possible, we recommend that you watch the video with the audio on. On the outside scene you can hear the screech of blocked left front wheel. On the inside scene the uppermost sound (after the net has banged on the engine hood) is only the textile brake rumble as car chassis tone. The sounds of arrest bring the rough reality into the otherwise smooth operation. The car is stopped from 100 km/h or 60 mph in about 2,2 - 2.4 seconds, counted from the moment of entering the net. The average deceleration is over 1 g. The stopping distance was here the usual 30 meters from 100 km/h.

The photo is a link to download the QuickTime/Cinepak-video. The video shows 5 frames/sec and has an uncompressed size of 2.4 MB.

that's

The video requires a QuickTime to play. In case you don't have it, the latest version of QuickTime can be obtained from here.

In the test on the video above, the masts were of the so called spring-type. The masts are pivoted down again strong springs and locked. When released, the masts will pop up in half a second. In the above video the masts were readily up. The Spidernet with all the masts and other equipment goes yet into a man carriable size. In the photo below the textile package contains the net with brakes etc. attached to it. The metal mast poles are on the top of the textile pack and the rest of the mast accessories are in the wooden box. The textile pack is packed ready for set up, after opening the red zipper in the middle the cover package is split in half. Then the net can be pulled, using the anchoring hook directly over road from one anchor to the other and the Spidernet is ready for set up.

spidernet packages photo

The Spidernet setup time from package to ready for arrest is only minutes. The set-up time is not less than one minute but no more than five minutes, depending on number of men and where it is to set up. Two men can operate the Spidernet without any difficulties. No more than four men can work on the system simultaneously. The release of the downpressed masts is made either by pull ropes or with one electronic handset, photo below. The handset initiates the lift-up very fast. When using the handset for liftup, the net can be lifted up exactly at the chosen moment, which is both a tactical and a safety feature.

handset.144pix

When the net is locked down, all traffic in both directions can safely pass over the net without danger. Below photo is from a Nurmijärvi Police traffic control, with the Spidernet set up some distance after the control point.

poliisi

Below is a link to a video showing the handset activated, 4 lanes wide SPIDERNET arresting a 60 mph (100 km/h) oncoming heavy car. The audience is truly amazed of the live performance of the SPIDERNET, which you can clearly observe on the audio track of the video. Click the photo to download the video. The video has a size of 4 MB.

live_test_at_60mph

The video requires a QuickTime to play. In case you don't have it, the latest version of QuickTime can be obtained from here.

Hope you enjoy this video as much as did the live audience enjoy the SPIDERNET performance.

Contact info

A-Laskuvarjo
P.O. Box 130
Verkkomäentie 35
01801 Klaukkala, FINLAND
Tel: +358 9 879 3 878
Fax: +358 9 878 9 3040