Military recon powerboat concept

[FAST FRED]

"Submarines are by nature far less visible."

NOT to us ASW folks , subs make NOISE , not much , but usually enough to track & kill.

Torpedos go WAY! faster than subs, even nukes.

FF

[brian eiland]

I spent a few years working with the subs back in the early 70's with the intro of Mk48, Subroc, etc. And ASW as well.

I'd place my bets on the sub, given the choice

[FAST FRED]

I'd place my bets on the sub, given the choice

Even knowing many torpedos have Nuke warheads?

Overpressure kills subs at depth , nukes are good at overpressure.

I would expect tho the next attack on the USA will be with purchased bio weapons from the many excellent well funded Cuban labs.

FF

[Kobus Potgieter]

I have also been working on a stealth project and have been doing a lot of research in stealth technology. I agree with the comments - this design is not stealth at all. Stealth is the angle of surface placed in such a way that it reflects the radar signal. This is stealth. Your design will work quite well as an offshore racer.

[kach22i]

Originally Posted by Kobus Potgieter

Stealth is the angle of surface placed in such a way that it reflects the radar signal.

It seems then that you have at least five choices.

1. Surface piercing hull so that the hull is angled skyward and not downward to be reflected by the water.

2. Make the craft out of something radar transparent in lieu of radar reflective.

3. Coat the craft with a magic-like radar absorbing material.

4. Put it under the water as suggested earlier.

5. Make it go over the water like a SES or hovercraft, and treat the surfaces under the skirt with great care. The skirt maybe out of a material to abosorb radar waves - or not.

[Kobus Potgieter]

Originally Posted by kach22i

It seems then that you have at least five choices.

1. Surface piercing hull so that the hull is angled skyward and not downward to be reflected by the water.

2. Make the craft out of something radar transparent in lieu of radar reflective.

3. Coat the craft with a magic-like radar absorbing material.

4. Put it under the water as suggested earlier.

5. Make it go over the water like a SES or hovercraft, and treat the surfaces under the skirt with great care. The skirt maybe out of a material to abosorb radar waves - or not.

point1 . remember that the topside play a major role with rader deflection.
point3. radar absorbing materials are available. a good sandwish construction also help to a point. This is however very expensive
point 4. what can i say
point 5 . whatever is above the WL, radr will pick up and again surface angles are important.

[kach22i]

Originally Posted by Kobus Potgieter

point1 . remember that the topside play a major role with rader deflection.

For air to surface "looking down" radar I would agree.

However surface to surface radar would pick up the lower hull to water surface interaction, right?

Or would the radar waves be bounced high upward away from the source?

Sample:
http://www.physorg.com/news64672001.html

Note how much attention has been paid to making the ship less visible to radar – all exterior surfaces are smoothed and angled to present the smallest possible profile – almost looks like a surfaced sub, its primary enemy.

[brian eiland]

Originally Posted by brian eiland

....And finally I was going to ask if you had ever contributed your views of this design to that subject thread at Yachtforums,
Trimarans and the Bladerunner
http://www.yachtforums.com/forums/general-yachting-discussion/2701-trimarans-bladerunner-7.html
..but I just looked there and found you did recently make a posting. I think you should repeat that posting you made here and see what reaction you get on the other site??...should be interesting

Great learning on these forums...information sharing!!

For those who do not frequent this other forum there have been a few interesting additions recently.

[kach22i]

Originally Posted by brian eiland

For those who do not frequent this other forum there have been a few interesting additions recently.

That Triton on page 8 (with links) is an odd duck, but I like it.

[dan lys]

hey alex its dan lys your old clay modeling buddy from ccs, email me at dlys83@hotmail.com, i just heard ur out in minnesota or some shit like that, hit me up asap cause i might be headin down to miami and i figured id catch u for a drink, hit me up guy......oh ya and i heard rob cameron got married lol u kno his wife controls his ass lol, oh and miljan just got into toyota, theyre working his ass off he told me......nice boat by the way lol....k guy hit me up cya

[rambat]

Safe Walrus has said it best I think "Remember as has been said above stealth ain't just about low radar signature! People got ears and can use 'em so you need QUIET engines "

Effective clandestine jobs done from small boats have to mostly go under "human radar", seldom is there active radar in regions were we are "not" officially involved. A real stealth insertion craft should have sophisticated mufflers, low profile design to get lost in even slight waves, over the horizon range and speed to limit the time at risk of exposure. A real different scenario from stealth requirements of bigger surface ships.

Biggest issue to encourage all of us to start discussing (smaller?) hull alternatives is not speed or radar stealth but to improve human factors. We have simple platued with our ability to take a seal team at high speed on a Vee hull and have them ready for anything other than triage. Any offshore racer will confirm the bloody urine and the compressed spines, yet racing is a hobby, not regular deployment, its a real problem. We could devise a suspension couch or complete cab separate from the surface hull, like this butchered Mark V. render. Won't help the mechanicals much....

I'll show my bias here again and suggest an Air-Cushion hull is the best next evolution. This thread showcased the Blade runner, I love its look and it was a bold brave venture. I will try to be as bold and suggest a "phase two" be explored by the application of a full bow wrapping bag/finger seal. I showcased this similar "Hybrid" SES hull form a few months back, it could be argued this set-up would soften the ride, maintain a flatter roll, eliminate that scary bow pitch potential. The over all HP could be shared to drive some fans for about the same speed, since the overall drag goes down. Those side sponsons could be modified as planning amas for roll stability and digging resistance. BMcF could add something here I am sure

[kach22i]

FYI: An old post of mine from the Hovercraft Club of America forum...............

UPDATE: 10/18/2007
http://www.hoverclubofamerica.org/fo...90&#entry13190
This is the first information I've seen on underwater sounds made by hovercraft.

The Journal of the Acoustical Society of America
http://scitation.aip.org/getabs/servlet/Ge...ps&gifs=yes

Underwater and in-air sounds from a small hovercraft

Susanna B. Blackwell and Charles R. Greene, Jr.
Greeneridge Sciences Inc., 1411 Firestone Road, Goleta, California 93117

(Received 3 August 2004; revised 9 September 2005; accepted 19 September 2005)

Underwater and in-air recordings were made from a boat anchored near Prudhoe Bay, Alaska, while a Griffon 2000TD hovercraft drove by at or near full power on four passes. At the closest point of approach (CPA, 6.5 m), underwater broadband (10–10 000 Hz) levels reached 133 and 131 dB re: 1 µPa at depths of 1 and 7 m, respectively. In-air unweighted and A-weighted broadband (10–10 000 Hz) levels reached 104 and 97 dB re: 20 µPa, respectively. The hovercraft produced sound at a wide range of frequencies. Both underwater and in air, the largest spectral peak was near 87 Hz, which corresponded to the blade rate of the thrust propeller. In addition, the spectral composition included several harmonics of this frequency. The shaft or blade rate of the lift fan was barely detectable underwater despite its proximity to the water. The hovercraft was considerably quieter underwater than similar-sized conventional vessels and may be an attractive alternative when there is concern over underwater sounds. ©2005 Acoustical Society of America

EDIT:
A thread on acoustics and sound..........
http://www.hoverclubofamerica.org/fo...3&hl=acoustics

[kach22i]

Originally Posted by rambat

I'll show my bias here again and suggest an Air-Cushion hull is the best next evolution.

What was your old user name?

DCCD, David - right?

[rambat]

Yes, dccd or Rambat I must be registered twice as I have long lurked and seldom commented.

We as designers need to think about mission phase, long range transits have different priiorityies than up close insertion. So if you have an ACV/WheledAmphibian, it could be hull born for economy transform into ACV mode to get over shore. Just the opposite if the transit needs to keep the men fresh and you can go feet dry with wheels etc..

Rotorcraft can do it all except keep quiet, carry any real load long range or do it cheaply while losing itself in the surface clutter Again I think a Mark V sized ACV using the old Bell 1967 SKRM-1 as a starting point could be the answer and am working up just a design. The US Navy SKMR-1 was a 6' gound clearence flying 25 ton Air cushion craft, built in 1967. Its particulars were 45000 lb, plus 2000 lbs payload, 8000 lbs fuel, 4320 hp total, 70 knots. Noise wieght and controlability killed it as it has sidelined hovercraft design ever since. I will apply in my new design 2007 composites to save 60% strucure wieght, offer 2x2000 hp gasoline "silenced" engines (short missions) elec stability and eliminate the axle fans and thier mission killer noise. Stay tuned. And feel free to offer any constructive comments.

[GTO]

I think an objects radar signature is much more complex than just plate angles and putting a coat of RAM over a structure.

Having worked "around" some radar analysts and technicians, there are a couple of points worth mentioning that make the entire "stealth" vehicle a difficult beast to design.

1. Most everything has a radar signature.
2. Radar reflections interact. For example, 2 point sources may either amplify each other (peak-peak), or cancel each other out (peak-valley). Also, this means that the resulting radar reflection path may not be what one would expect from the angle of the reflective part. As the reflected radar waves interact from various sources on the vehicle, you could end up with a beam pointing right at the transmitter. Essentially, a passive phased array (or electronically tuned) beam.

So what does this mean in real life?

If coatings and plate angles for a design are not fully analyzed/tested, as a whole, it is possible that the resulting radar signature could be even worse than a standard "non-stealth" design.

Take a RAM coating for instance. Slap on layer of RAM paint. Okay, test results indicate a reduced signature. Well more is better, right? Paint on another layer. Now, the signature is much worse. What happened? The two layers of RAM had returns that amplified, negating the RAM.

Anyway, if this is basic info everyone here is aware of, sorry to waste the space.