Heliferry Concept - innovative boat design

i wisely restricted myself to only reading this thread but some questions came up immidiatly like tail rotor twist, when powering the top rotor with jets (or CR blades) i read somewhere there is no need for a tail rotor? this rotorwing was allready playing in my mind, i've played with a model in a windtunnel on a aironautical fair as kid and if i recall rite it had lots of lift and drag, cost of assembly and malfunction are other considerations. i aint the expert here but find these things fascinating allrite, what do you think about a rotor wing for a WIG?

 

There are several ways to deal with the counter torque from powering the rotor: tip jets as you put it well do not require it; some forward speed with counter rudder is another solution; as the heliferry is a twin prop, they can also provide counter torque (one of the props going in reverse). It is only an issue during the prerotation (nothing compared to what traditional helicopters need)

The fanwing is an interesting concept. I have been following its progress too. The particular shape of the wing points "naturally" to WIG wings. The developer of the fanwing invites anybody to try it out in that fashion as he is too busy with his present line of applications. However, the fanwing is a very particular arrangement not to be mistaken with other rotating wings (which the fanwing is NOT) that, incidentally, have more in common with the cycloidal props. But a discussion would lead too far astray in this thread.

I suppose the principle of the fanwing would work under water too, but I cannot see how to make a case for it. Can you?

 

ok this is the heliferry concept thread but thanks for a good reply on the fanned rotor wing luc, at least i'm not nuts and wouldnt mind continuing the discussion later. at present however i'm down to earth deep down in the bilge renewing impellers. when taking those pumps loose water poors in trough the hoses, so hold them up above the waterline or have a wooden cone ready as stopper, things that took me minutes to realise holding my hands on the hoses, and showing i aint Thaaat smart sometimes. (did compare and counted the rubber that came out of the termostat with the impeller)

 

Show me the data

For those of you in search of more engineering meat in the description of the HeliFerry concept, please consider going through the hefty 2003 NASA report entitled: ”An overview of autogyros and the McDonnell XV-1 convertiplane” found at http://rotorcraft.arc.nasa.gov/publications/files/NASA-CR-2003-212799.pdf

This document tackles the hard problems of the rotor in combination with a fix wing. The HF, however, is easy in comparison as it stays way clear from the fringes of the operational envelopes discussed in the document. For the HeliFerry,
1. replace the three bladed rotor with a two bladed, high inertia Carter rotor as described in http://www.cartercopters.com
2. drastically downsize the engine and live with STOL instead of VTOL and profit from the efficiencies of much lower max speed
3. replace the high wing with a low WIG wing to obtain similar L/D ratios but at sea level.
4. integrate a fast steady hull with the fuselage.

This is another way to formulate the HeliFerry concept and refer to the hard core engineering behind the hardest of the challenge designing this triple compound craft.

Luc

 

Ahoy there mates

New guy on board...been around for a while though. I just wanted to say that I was reading this thread and wanted to express my opinion that LUC, FOX and TOM are all correct in their statements. Tom is correct because you cannot escape the inevitability of the numbers. LUC and FOX are correct because of their understanding of "the nautical feel" for a design. I don't say this as a physicist. Instead I say this because before we reached a mathematical understanding of the laws of physics and their inevitable functions in the different stratas of their domain, we were designing craft based on the "scientific feel for the art" or on observations of the performance of those designs. This is historical and unchallengable. However, we have reached a level of mathematical understanding and must therefore design by the numbers, with a little bit of the "scientific art" included. I have designed many craft, some sold, some didn't. Some I built, some I built to model scales. All were beautiful to me in their art and correct in their numbers. Remember that 2+2 =4, just as 3+1 and 5-1 = 4. Therefore we can agree to disagree as long as the end result is factually the same. Ahem, thought I'd mix a little bit of chaos theory and philosophy in there.
In any event, I have decided to go to another parallel level. I have been researching WIG effect craft and hovering craft and have decided to design a hover wig. Actually, I have some lines drawn in CAD already and was wondering if the minds of this group would consider belaboring the design and perhaps collaborate on its completion. Please understand that I will design as always, by the numbers and nautically aesthetic. All criticism will be welcome as long as it is constructive and productive. You can tell me you hate it, but then tell me why and justify it. Whether it be by the numbers or aesthetically is up to you. So whatdaya think? Anybody want to help with discussions on my thoughts or the design that I am proposing? :idea: Oh yes, I am also designing a foil that I don't think has as of yet been published which I believe looks very promising for WIG effect craft which I hope we can also belabor at length because it is my belief that the shape of the the foil for this craft should not be based on the upper camber which is typical for the shape for free flight. Instead it should be based on the lower portion. Anybody concur or contradict this line of thinking? Why?

Jay

 

Hi Jay, I'd like to see what you have in mind. I have been thinking along the same lines regarding a foil based more importantly on the lower surface than the upper. My thinking for this goes back to the anhedral reversed delta shape. As the basic Lippisch configuration seems to develop about 80% of it's lift from the dynamic ram of the lower surface and only about 20% from the upper cambered surface, it seems to me that this effect would also apply in the water medium, thereby diminishing the effect of the loss of lift in a conventional foil as the foil transitions from the water to the surface. I haven't done any actual research to test out my theory yet, but what do you guys think?

Russ

 

Hi Jay, I'd like to see what you have in mind. I have been thinking along the same lines regarding a foil based more importantly on the lower surface than the upper. My thinking for this goes back to the anhedral reversed delta shape. As the basic Lippisch configuration seems to develop about 80% of it's lift from the dynamic ram of the lower surface and only about 20% from the upper cambered surface, it seems to me that this effect would also apply in the water medium, thereby diminishing the effect of the loss of lift in a conventional foil as the foil transitions from the water to the surface. I haven't done any actual research to test out my theory yet, but what do you guys think?

Russ

Hmmm, I tried to do the quote thingie and it didn't work. Anybody have any ideas why?

Hello Russ... I would be happy to discuss my thoughts about the foil I'm working on right now. I just want to clarify some things you mentioned.
The anhedral (opposite of dihedral) reverse delta wing as we all know was a tremendous accomplishment for wig effect. But it wasn't just because of the percentages of lift that you stated. Which by the way I was not aware about. The reverse delta in this case works excellent because it is in ground effect where most of the area of the foil is forward and therefore, more of the pressure and lift. The anhedral in this case is perfect for creating the enclosure or "tunnel" (which by the way is representative of a converging cone from leading edge to trailing edge) and because the vortices won't complete their loops (translates into less drag = greater lift) which will be useless for free flight. This is evident with the AV8B Harriers which are designed to hover. The anhedral design is actually very unstable but the beauty of that instability is that it creates an incredible amount of longitudinal stability while in ground effect. I think that this design will be unbeatable for this purpose but im my opinion it could be improved upon. However, it is a fixed wing and my thoughts on my foil is to have the flexibility to remove them and to adjust their angle of attack instead of achieving the angle with elevators. My theory (mission statement) is that with the correct foil, I would be able to lift the fusealage level with a high angle of attack at a much slower speed. Level means longitudinal stability at all times, high angle of attack means maximum lift at minimum acceleration which translates into maximum safety. I can then transition into higher speeds and smaller angles of attack until I am at the desired speed while maintaining the fusealage level.
Assuming that I understand your statement about deltas as hydrofoils I'm not convinced that the reverse delta would be very good in H2O because you must remember that although air is a fluid as water, water is approximately 800 times denser and drag with so much area would be significant. Cavitation upon its ascention would be unbelievable.
Now, here are my thoughts on my foil. Thin (thin is relative), reflexed elliptical upper with flat, reflexed lower. The forward portion of the foil would be somewhat concave on the lower side which would create a high pressure differential, thereby a higher stall angle. The leading edge radius would be huge (huge is also relative). I'm working out the percentages and will need to do serious testing at different angles of attack to maximize it. This is pretty complex right now because in the absence of a wind tunnel I have to mathematically compute lift and drag by manually calculating and drawing many theoretical vortices and then solve for their differences. Very accurate but insanely tedious. What do you think?

Jay

 

Russ, I happened to be in the neighbourhood. If I stopped in at your shop would there be anything cool to see? I might have a little bit of time on October 19th, can I come visit?

 

Ahoy Russ...

Been a while since you been on...hope everything is okay. I was looking at your site and was impressed with your model...very sci-fi looking. This is a compliment because I love sci-fi look. Anyway, I was wondering if you did any tests on the model? Did you consider a "neutral" fusealage in your design or does the fusealage contribute lift to the design? I ask because you should be aware that only NASA and a couple of amateur designs have designed fusealages that contribute lift. Very, very difficult to do effectively and justifying the attempt just because the fusealage is addittional area so it should contribute lift just doesn't pan out. Anyway, I completed the rough design of the root and tip of the foil I'm working on and was wondering if you would like to discuss it once I have calculated and documented all the x/y coordinates? I really want to streamline it a little more, but I figure that maybe I should give it a go. Whoee, this thread seems to have stalled. I did a little supersonic wave surfing the other day and found a couple of sites that offer (FREE) plans for some very, very nice wind tunnels. I'll get the url's to you the next time we intercept. I am giving some serious thought to maybe building one for this foil.

Fair winds,
Jay

 

Jay,
I just caught up with the thread. The description of your thinking does not go beyond WIG tradition as far as I can tell. I suppose you are aware of the wig page www.se-technology.com and its resident airfoil calculator. There is also a WIG forum where this discussion might be more appropriate http://autos.groups.yahoo.com/group/wig/
Furthermore, I assume you are aware that your wind tunnel would also need a moving floor.
In any case, I wish you the best with your experimentation.
Luc

 

Ahoy Luc...
Yupper, went to the wig page which is supported by SE-technology, but they do not offer their airfoil calculator. You have to become a member and then you can use the NACA or DHMTU foils from Russia. But the information for those foils is highly limited from my understanding. How much information do you know of these foils? My thoughts on my foil are to have a tip that is larger and more cambered than the root which I'm not sure is exactly within the tradition of wig foils. Is it? The only place that I found will offer a virtual airfoil calculator that allows you to input your own coordinates is at microcfd.com but only good for 3 days then you have to purchase. I'm not sure that the wind tunnel would need a moving floor but I'll bite...why? I think that although drag may increase due to the enclosed envelope, lift also increases due to the close proximity to the deck so results could be higher drag but negligible overall.
I looked at the other forum at Yahoo that you mentioned but I haven't lost interest so I'll just hang around a bit. Thanks for your good wishes...I would be happy to update you on my progress and I hope I can pick your brain from time to time if needed. The Heliferry concept seems sound. Will the rotors fold back while in ground effect or ram effect? Which envelope will it operate in? Will it be ram (h/c<.1) or will it be ground (h< .5(s).? Did you know that at about .03 to .04 all conventional free air foil L/D values doubled? I hope my foil triples those values. Tee Hee. A brief dream.

Jay

 

Information about them is not limited if you know Russian.

I guess it is not. What would be the logic?

In reality: craft is at speed = v; ground at speed = 0 and let's say wind at speed = 0
In tunnel: craft is at speed = 0; then ground and wind must be at speed = -v to give equivalent effect, right?

The rotors do not count on operating in ground effect because at that height there is hardly any left. They are just there to get the craft on its ground effect low wings, bypassing the displacement drag hump. After that they are off loaded and slowed down to reduce drag (cube of rpm). Operating height will depend on sea state. Rotors remain less off loaded at higher cruise to pick up the slack in GE lift.

Luc

 

Hello LUC...

Actually I meant that not much information has been published on the foils because it is still in development, Russian would be easy to translate with PC's nowadays.

The logic behind my design for the root and the tip is not so logical. The mathematics however, point to this crosssectional shape. Data shows that a thin airfoil 5.5-6.5% of cord works exceptionally well for takeoff and a thicker section will provide more lift during cruise. The leading edge radius will be huge to minimize the shift of the center of pressure and to establish the suction peak at the leading edge. This will of course also reduce nose down pitch which means you don't plow into the ocean at 100MPH which translates into you get to live. My theory is that this crosssectional shape will translate into good lift, zero or slight positive pitch and a reduction of the lower surface center of pressure (which you know can be as much as 55-60% of aerodynamic cord while in ground effect) to a more acceptable 30-35% which places the foil in ground effect at a stability level of a foil in free flight. Also, it should be noted that the foil design I am creating will have the following attachment specifications:

'Must remember that I am not developing a fixed wing, there is a near trailing edge pivot so that take off occurs at high aoa and low mph and then transitions to low aoa and high (high meaning efficient) mph. If I need to ascend a little I can increase aoa slightly instead of mph and if I need to descend, I reduce mph and then increase mph to maintain height.

At take off transition...the root AOA will be 8.5deg and the tip will be 7.5 deg.

At cruise...the fusealage will be level, the root will be 1 deg and the tip will be 0 deg.'

This attachment for the craft should translate into more lift at the root which is the thinner section and the tip will create lift anyway because it is more cambered. But remember that I am only refining the upper section, the lower section is my actual development study because I am convinced that the lower section is the crucial area for WIG effect craft.

You stated that operating height for the Heli will depend on sea state. Are you implying that your craft will not be subject to the laws that govern the ground effect envelope and that the efficiency of the craft in that envelope is not important or did you mean that you can arbitrarily power up the rotors and remove yourself from the ground effect envelope for safety purposes while still attaining acceptable efficiency of operation? Please clarify.

Actually your explanation for the wind tunnel craft is accurate but lacking mathematical variables. First, please recall that I said that there was a difference between the results but they were negligible. They could become substantial if we rounded off to say <.x-25. Another variable is that the ground and wind will be at zero when the craft is v will only cancel itself if the craft is directly upwind or downwind. Any other vector will change those figures and disqualify that statement for the craft. Wind abeam being the most evident of all angles.

Fair winds...
Jay

 

1. My impression was that the DHMTU foils were at least 25 years old and had been the basis of most Russian WIG developments.

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.

3. This is a novel approach, but requiring big bearings ... What about approximating the effect with flaps and slats?

4. The lift is distributed between wing and rotor. Preferably, the wing is in max GE and carries all the weight with the rotor completely off loaded. GE drops off pretty quickly with in creasing height. The higher the waves the more the rotor will loaded to pick up the slack in GE lift (of course, at a cost of burning more fuel, but not grounding the craft).

Luc

 

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.

Man, since I've been away, a lot to consider has cropped up and I
don't have a lot of time to go into detail about my thoughts on everything
said ...

About the density of water related to the foil - anything touching or
dragging the water surface will create huge amounts of drag ( as compared
to the drag the same foil would create in air) however, I think its all
'relative'. 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.

Luc gave his answer about the 'moving floor' of the wind tunnel. I don't
understand the formulas like some of you guys, but this is my concern
regarding 'wind tunnel' testing of water surface craft such as Type B
WIG's in a conventional wind tunnel ... this might be a very informative
tool if the craft is surrounded with a flow of air(ONLY). However, how can
wind tunnel testing take into account intermittant contact with a fluctuating
fluid surface which is 864 times as dense as the air flow over the upper
surface 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 ?

It's going to take me a while to digest all the other discussion in this thread,
but keep it up, Guys! I find this discussion very interesting.

Note to Thunderhead19 - Thanks Jeremy ... check your email.

Best Regards

Russ