Heliferry Concept - innovative boat design

[JCFARER]

Originally Posted by lucdekeyser

2. Charles Bixel over on the other forum would love to hear from you. He has been a preacher in the desert about the GE efficiency of flat foils.

Hello Luc..

Was called to give a lecture, so I come out of retirement every now and then.

Oh yeah...what other forum? Maybe I canpick his brain a little bit.

Jay

[JCFARER]

Hi Jay, thanks for your concern. No, I haven't fallen off the edge of
the earth ...yet - I've been out of town working on a project , so have
been away from my computer. I'm out of the 'bush' for Thanksgiving, but
will be back there next Monday for another couple of weeks.

Hello Fox...

Glad all is well. Me too, was called to lecture and it's excellent money, so I come out of retirement every now and then. Will be doing it again 2x this week.

The cavitation (upon ascention) IS a serious limiting factor with a conventional foil, however, I think, it would be less significant to the
operation of the craft with a Lippisch foil, because as the cavitation on the
upper surface increases [as the foil transitions through the surface], the loss
of 'lift' is only approximately 20%, while the lower lifting surface is
still providing an effective 80% lift to the foil. It seems to me that this
is essentially the reverse of a conventional foil. I think this has
always been a speed-limiting factor to the use of regular hydro-foils (which
are essentially conventional aero-foils) in that, as a regular foil gets
closer to the surface it loses lift, settles back to a level which increases
lift and therefore causes porpoising of improperly designed hydrofoils.

Ahh, yes it is true that it is a limiting factor in water for typical foils, but the same would hold true for the Lippisch because the area of the foil will work against it's lift properties and in favor of drag much more than you would probably imagine. You may want to revisit this thought with more scrutiny.

However, how can wind tunnel testing take into account intermittant contact with a fluctuatingfluid surface which is 864 times as dense as the air flow over the uppersurface of the craft? In my view, unless you can constantly replicate contact the ever changing surface, a wind tunnel is pretty much useless for this application unless you combined a wind tunnel with a wave tank to test the craft ... IMHO ?.

Oh boy... I lectured on this. I will try to make a two hour lecture as short as possible in order to answer this, and I'm sure Luc knows about it but neither one of us brought it up. Think of rain on a free air-foil. The same would be true for spray on a GE foil. The physics, is actually inherent in the foil and its use. Most all sections are "Turbulent" and are ever hardly effected by spray or rain or any kind of surface contamination such as insects or roughness. I can't make it simpler than that. Therefore, the tunnel test is accurate. However, there are "corrective" mathematical formulas that take into account the different areas and distances from foil to the wall, floor, ceiling, entrance, exit etc. in the tunnel for a truly accurate result. This result is ofcourse negligible for our purposes and would apply to supersonic foils or better.

I really like this thread. I'm still working on x/y coordinates for the foil...stay tuned.

Jay

[lucdekeyser]

Originally Posted by JCFARER

Hello Luc..

Oh yeah...what other forum? Maybe I canpick his brain a little bit.

Jay

Chuck orates at length on http://autos.groups.yahoo.com/group/wig/
Luc

[foxxaero]

Jay, just some clarifications on my previous statements regarding a Lippisch
HYDRO-foil, and the wind tunnel to see if we are still on the same page.

Regarding a Lippisch (anhedral reversed delta ram foil) for use as a hydrofoil, I am referring to a small hydrofoil (not an airfoil). I do recognize that the Lippisch AIRfoil is ONLY effecient while in GE - after leaving (ascending above GE), this and other types of WIG foils become inefficient as compared to conventional airfoils in 'free flight'... but, my thinking was limited to the use of the Lippisch design only as a small hydrofoil.

Even so, I would admit that Lippisch configuration under water would be subject to more drag than a conventional (and similarly sized) hydrofoil. However, at this point, I am limiting my design-thinking to the cavitation which would be encountered as the foils ascend and reach the water surface.

In a conventional hydrofoil (the inverted T - types); The upper foil surface loses lift as it approaches the surface, causing it to sink back to its proper operating depth.

My thinking is that, although a Lippisch style hydrofoil would also suffer from upper foil surface cavitation, it would not be enough to cause the foil to sink back down to a lower level in the water, because of the ram-effect of the lower foil surface, which would still be applying approximately 80% lift to the foil, and in theory,it should pierce through the surface, and then begin to operate as a hydro-ski. It is this aspect only which I am interested in at this point in time, and I recognize that there would be higher drag related to a Lippisch style hydrofoil while in the water than a conventional hydrofoil.

Also, with the wind-tunnel ... I was referring to the transition stage at take-off (when the craft is slapping wave crests and not quite fully clear of the surface)... not the minor effects of rain, spray, or insects colliding with the foil surface after once entering GE. The transitional stage is (in my view) the critical stage when the craft is no longer supported with water ONLY or air ONLY. How could this stage be replicated in a wind tunnel, unless it also incorporated a wave motion 'floor' so that effects at this stage could be tested accurately in the tunnel?

[JCFARER]

Originally Posted by foxxaero

Jay, just some clarifications on my previous statements regarding a Lippisch
HYDRO-foil, and the wind tunnel to see if we are still on the same page.

Also, with the wind-tunnel ... I was referring to the transition stage at take-off (when the craft is slapping wave crests and not quite fully clear of the surface)... not the minor effects of rain, spray, or insects colliding with the foil surface after once entering GE. The transitional stage is (in my view) the critical stage when the craft is no longer supported with water ONLY or air ONLY. How could this stage be replicated in a wind tunnel, unless it also incorporated a wave motion 'floor' so that effects at this stage could be tested accurately in the tunnel?

Foxx...

Hawdy

Ahh, nope. I have no knowledge of any tunnel test that measures these different variables. I thought you meant the spray created from takeoff. However, I am absolutely certain that these craft have limitations of transitional operations...in other words, the foils are either high enough so that a clearance is established for transitioning into GE or a wave hight limiting factor for operations is established. In either case, I am not aware of any foil that strikes the wave crests while in transition or in GE with its leading edge. At that speed, the collission would be explosive, not to mention that even if it was a clean cut, the upper portion of the wave would be a substantial amount of displacement on the foil. It is my belief that the forces would be tremendous and in fact may not allow the craft to enter ground effect or, one good whack would mean a substantial positive pitch that may in fact be unrecoverable longitudinally, which translates into a backward flip of death and destruction.

Wow...what is the clearance on this foil? I hope that there is enough AOA to at least take some of the whacking on or relatively close to the CG of the craft.

Jay

[aztek]

Hi
isn't it just alot of stuff that works well on its own (WIG craft, chopper and hi speed ferry) chucked together and prayed for?

[eponodyne]

I get that impression too, Aztek. it looks to me like any of these might be okay on its own, or pehaps in combination with one other, but all three technologies all thrown in the same pile and then smeared with buzzwords make me think that nothing is ever going to come of this besides some interesting theoretical discussion on the Boat Design forum. SO, thank you to the inventors and thank you to their investors for adding to our vast library of WHAT WON'T WORK. Remember, according to the Scientific Method, no result is a 'bad' result.

[kach22i]

I didn't know that we could add to a post from back in 2004, I'm impressed.

Whirling blades over my head in a craft which cannot bank because it flies close to the surface.

Bad combination.

Hovercraft plus WIG is a good combination though.

[aztek]

Hi
this is something you might be interested eponodyne and Kach22i

http://www.ekranoplan-hit.ru/index-eng.html

[ancient kayaker]

It seems an unlikely concept. I'm comfortable with the hull and aerofoil aspects, but not the rotor. I don't understand the aerodynamics being thrown around in this thread, but I think I grasp the general idea, which is a WIG that functions like the venerable "jump-gyro" concept during the transition from low speed to high speed and back.

Given the cost, complexity and fragility of the rotor it is difficult to see what overall advantage this concept offers. I would have thought there were more cost effective, safer and simpler ways to achieve achieving WIG performance with less power. WIGs can hardly pop in and out of an unprepared habor without necessary facilities, so a launch ramp or a tow boat spring readily to mind. Then there's hydrofoils, which work even when limited to wind power, and the tried and true cushion craft.

As a try anything guy with decades of experience in aerospace engineering I would really like to think this would work. But I'll need a lot more convincing. Or is it dead already?

[kach22i]

http://en.wikipedia.org/wiki/Autogyro

Cierva was troubled by the stall phenomenon and vowed to develop an aircraft that could fly safely at low airspeeds.........

However, the CAA's assertion that autogyros have a poor safety record means that permit to fly will only be granted to existing types of autogyro. All new types of autogyro must be submitted for full type approval under CAP643 Section T.[9]

Gyroplane FAQs
- By Kerry Cartier
http://www.pra.org/index.php?option=...120&Itemid=110

[lucdekeyser]

I understand the skepticism with respect to the rotor technology used in the heliferry since it was introduced in 2002. Without background in its aerodynamics this is a prudent reaction on a forum without organized peer review before publication.

Therefore, I am happy to announce that:

Carter Aviation Technologies LLC (Carter) of Wichita Falls, TX is announcing that they have completed negotiations with AAI Corporation, an operating unit of Textron Systems, a Textron Inc. company, of Hunt Valley, MD on an exclusive licensing agreement for Unmanned Aircraft Systems (UAS) using Carter's revolutionary Slowed Rotor/Compound (SR/C) Aircraft Technology - a combination of rotorcraft and fixed-wing aerodynamics.

Spending that much capital does not happen without extensive engineering "peer review". Contracts like these increase the chance for reaching the critical mass that will drive the price down to levels that are sustainable for typical WIG transport operations.

Luc

[Brian@BNE]

Luc, not sure about 'that much capital' as there are no numbers! I'll be interested to see how things develop.

Reading the thread reminded me of the Fairey Rotodyne. Its performance was fine eg 48 pax, 213 mph, 520 mi range. And the noise was being worked on. Perhaps it was before its time? Corporate politics did as much as anything to sideline it.
http://dunnbypaul.net/aircraft/rotodyne/

http://en.wikipedia.org/wiki/Fairey_Rotodyne

One of its original patent holders was AG Forsyth, and his grandson is a friend living just up the road. He has 3 ft long model of the Rotodyne in his living room, always a talking point with curious visitors.

[lucdekeyser]

Brain, the Fairey Rotordyne is often brought up in this context and yes it deserved a better future. But make no mistake, the slowed rotor high inertia rotor used in the HeliFerry is of a completely different technology. Rotordyne's technology would not have worked for HeliFerry's operational mission.

Luc

[ddrdan]

I flew in Uh-1N Helo's for four years in the Marine Corp. Rotor wash in salt water atmospheres is a PM nightmare. But that's typical .... just design it - forget about who has to work on it.