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Old Apr 30, 2014, 02:52 PM
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The NO-GUILT JETSKY: Bali 2015, any interest to build a solar panel HC+WIG prototype?

Hi everyone,

I am a French oil engineer leaving in Indonesia since 1984, presently at Bali & Lombok. My long-term goal is to achieve a functional one-seater open vehicle, but as many persons I see the stage of building and flying live RC models as the fastest and cheapest way to test and validate alternative configurations. Moreover IMHO, only persons accustomized to fiddle around with tons of models can have the creativity and the persistence to help in unproven project like mine.

Since "Hovercrafts" is the name given to this thread about air cushion vehicles (including WIG, PARWIG), let me start my story by pointing that several "experimental" one seater hovercrafts actually hover and move around (albeit slowly) with mechanical power in the range of just 400 Watt for 150 kg of total load, including Willy pictured below crossing the Thames in 2009 with human power only.

Therefore, assuming we would equip such vehicle with just TWO square meters of high-performance panels (solar efficiency 25%-30%) we could then get 500-600 Watt in sun-drenched meridional, tropical or equatorial countries.
It means that accounting 75% efficiency for engine/propeller, we get around 400 Watt of mechanical energy. One-seater hovercrafts could possibly hover and move from solar energy alone !!!!!


Now, let's dream we have the area and the budget to squeeze SIX square meters of those high efficiency wafers on the same hovercraft, the squeezing being illustrated by two three-wheeled road vehicles of the Japanese university of Tokay and of Netherland Nuna (both pictured below). It would mean that we would have now 1800 Watt to play with...
This TRIPLED energy supply versus slow-hovering shall open lots of new horizons, no ?
Including all kinds of fast magic-carpet rides above viscous water... Magic L/D ratio for a zero-carbon-emission thing "on" water...

Straight to my offer, now that efficient Japanese/Korean/Chinese/Taiwanese solar panels and LiPo batteries are decreasing in cost, I am interested to financially sponsor the models and full size prototype(s) of an electric light recreational vehicle as an alternative to our beloved but depressingly fuel-guzzling jetskis.

Not for personal profits, just to contribute to the fuel to electricity conversion movement, which is seemingly a goal of RC Groups too.
"In the long run men hit only what they aim at." — Henry David Thoreau

I call it "The no-guilt Jetski" (well, we need to find a better name since no jet engine will be used, at least for propulsion)
I see it as a rectangular open single-rider wing, floats at wingtips doubling as endplates, 6 to 10m2 of high efficiency solar panels on its upper surface (including on a large horizontal tail), 10-15kg of rechargeable LiPo batteries for take-off hump as well as for adrenaline bursts, electric paramotor driven.
Target 30 knot speed, usage envelop being limited to sunny days, wind below 12 knots.
Power will be insufficient to allow flight out of ground effect, like, named after a Foie Gras poultry, an unfortunate gigantic plane of our old friend Howard

Among high-efficiency technologies, I wrote off hydrofoils because of expected incursions of the vehicle on shallow water and above short strips of flat land/sand.

Therefore in high L/D efficiency, this leaves us with the choice of "hovercraft-like" technologies or of WIG technologies....

A bit of both worlds, Power Augmented Ram Air Wing In Ground effect (PARWIG) seems a good direction. It would allow to first achieve a decisive freedom from the infamous viscous liquid ("HC-like" or PAR) and subsequently, to achieve the desired high speed to power ratio (therefore pure WIG once airborne).

About the WIG shape, I am drawing conclusions from my own 25 years of hands-on passion with WIGs.
Equally important I have also compiled trials and errors of flying models of fast-building contributors on the web, including from the 1200 discussion posts on General Ekranoplan Topic here:
http://www.rcgroups.com/forums/showt...255615&page=80
So, like other contributors to RC Groups, the favored wing designs would be:
First (preferred) choice: the rectangular flat-plane wing, "Tottori university style" (some call it here a "Bixel" if two different airfoils are used), a few Aspect Ratios to be tried.
Second choice : the reverse delta "Prof AlexanderLippish style"
Third choice : the tandem wing "Gunther Jorg style"


The last picture below is a very preliminary rendering of what I have in mind.

Shame on me, getting older and overly busy with my earthly activities, this stunning project is at risk of slipping out of my bucket list...
Therefore, it would be great if a brainy and handy person could become interested to help this noble attempt and spend a few months at Bali in 2015. All materials, tools, Indonesian helpers, private villa accommodation and meals are on me...

Huge silver lining on this project, results don't need to be black or white !!
Imagine we would fail to produce sufficient solar energy on the available area.
We will possibly fly (a true first reward of its own) but the magic scooter will deplete its LiPo...
Waiting for futuristic superwafers, this possible failure in solar energy self-powered vehicles immediately translates into a success in the larger neighboring field of quiet/responsible battery-powered recreational vehicles!!!
If we fail by 25%, it means we have opened a 400% breakthrough
No it's not a Winston Churchill's quote
Yes, whatever the weight allowance for our LiPos, our 25% weak panels will however allow the rider to fly 4 times longer

And a fast charger is included too : At mid depletion, no need to leave turquoise waters to search for a power-grid outlet. Just enjoy our picnic (cold beer and fresh food in the tiny refrigerated box!!), a short nap, and we are 100% recharged again

Thank you for having read this post, to possibly comment on the best configuration and, if you find it worthy, for disseminating the offer to eligible friends.
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Old May 05, 2014, 04:57 AM
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That sounds like a great project maybe try a couple of the other forums as well this one is very quiet these days.
Im sure it will work just be careful if there is more than a slight breeze it will become airborne
I have added a pic of my own project which is aimed at energy efficiency -trying to get a non skirted peripheral jet hovercraft to work properly. I have had some success and measured speeds above 60km/h using less than 200watts which is pretty good for this type of model. I have often thought about the possibility of a solar powered craft but think using solar power just for lift would be practical with an IC engine for thrust ...The model in the pic can cruise along with minimal thrust due to the absence of skirt drag so i think theres potential to do something along those lines. Good luck with your project. pk
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Old May 08, 2014, 06:42 AM
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Originally Posted by windnsea View Post
. I have often thought about the possibility of a solar powered craft but think using solar power just for lift would be practical with an IC engine for thrust ...The model in the pic can cruise along with minimal thrust due to the absence of skirt drag so i think theres potential to do something along those lines. Good luck with your project. pk
Hi Peter,

Thank you for your moral support and your feeling that the scooter could fly.

Yes sadly the HC family seems a bit quiet...

Your two "hovercrafts" look amazing !! Like aliens' flying saucers !!
I watched your two models and your 3 videos... That's stunning !!

As good as PARWIGs !! (your design having a better flexibility and probably a better efficiency at low/medium speed but the WIGs reaching at higher speed a greater L/D ratio of 15-20 and saving energy by phasing down the RAM air system.)

As you are hinting, ability to travel on various surface with minimal thrust is the key. The laws of Newton dictate that no (much) power needs to be used for just maintaining altitude.
Easy on tarmac, more futuristic/difficult above water... When we truly achieve that efficiency like HCs or WIGs do, electric engines can possibly replace IC engines (at least for quiet recreational vehicles in area where IC engines would be barred).

In the meantime, solar panels can be seen as a smart use of the large upper area of such crafts to recharge batteries along the way.

When you think about it, PARWIGs and your Peripheral Jet HC are trying to achieve exactly the same goal (moving fast over the viscous element, with low power on board, while doing it without the drag of a skirt).


All the best with your project. Keep us posted with more videos please.

(since I see you live "Down under", please come for some wine at your next trip to Jimbaran Bali. Maybe we shall join our efforts some days...).

Pascal
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Old May 09, 2014, 05:11 AM
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Thanks for the kind offer maybe when i get a larger model going i will fly over : )
I had to edit this clip to fit but you can see the improvement in perfect conditions.
I've been trying to find some info on other projects like this and wondered if you've ever come across anything similar? -Pete
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Old May 09, 2014, 05:50 AM
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Hahaha, if you can stay for a few weeks at Bali, we can possibly built together a prototype of Peripheral Jet HC or a PARWIG large enough for your return...

Your video is amazing!! Another dream coming true !! This alien thing flies/hover over water and sand effortlessly...
This is very puzzling for me since I thought pure peripheral jet HC request a very high speed of the jet to "seal" the cushion, were deemed too greedy in power to load ratio, and had all been replaced by skirted HCs.
Maybe your success has to do with the Reynolds number, the fact that a model is 10 X smaller and 1000 X lighter than a passenger HC (in your very particular size the sealing jet being then allowed to remain at relatively low velocity).

I am sure you have your educated guess why you were the only person (that I ever heard of) able to revive Mr Cockerell first offspring and make it work without spoiling power around ...

This is exactly this kind of L/D efficiency (even a tad better at speed since lift is almost "free") that I would like to achieve with my Electric PARWIG Scooter !! (The no guilt jetski).

I would like to ask you a favour, since I saw from your video that your "Flying Saucer" seems to generate lift from its own, could you try (on sand, first) to reduce the power of the lift fan while applying a bit of nose-up incidence??
My guess is that above a certain speed, your lift fan won't be needed (although the shape of your wing would make it a bit difficult to control in pitch maybe).

Anything similar? Yes and No ! I saw a few amazing videos of PARWIG models flying effortless over water (a dozen of different models). BUT this is the first time I see the same result achieved by a "Hovercraft"





All the best.

Pascal
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Old May 09, 2014, 07:46 AM
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i think the answer to using electric power is an efficient lightweight turbo generator to assist the solar. there was a company developing unit for cars but dont know if it went into prodution.
The peripheral jet only works well at low cushion pressure - similar to aircraft wing loading values. so there is a different design approach needed. -also the shape of the body around the slot is the key to making it work efficiently.

I tried i couple of test runs doing what you suggested and found the results encouraging but it still needs a minimal amount of lift running to form the rear air curtain to contain the cusion but the model stays almost level so theres not much drag. I think increasing the angle of attack to eliminate the need for the lift fan completely would require more thrust power anyway so no real adavantage in that. Its hard to compare a model to a real world situation , theres so many different things to consider. I tried a lot of different model skirt designs and found that increasing power didnt really achieve much. It took a long time to get the peripheral jet idea to work but by comparison to the skirted models of similar size and power the performance is a big improvement.

Have you got any more details of the solar project or is it just at the idea stage?
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Old May 11, 2014, 08:17 PM
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Originally Posted by windnsea View Post
The peripheral jet only works well at low cushion pressure - similar to aircraft wing loading values. so there is a different design approach needed. -also the shape of the body around the slot is the key to making it work efficiently.

Have you got any more details of the solar project or is it just at the idea stage?
Hi Peter,

I am glad you are also tinkering with true WIG flying. A properly designed WIG always had a better L/D ratio than a properly designed HC. The HC just has a set of different benefits. And heavily loaded WIG need a PAR to take off, which makes their design and operation cumbersome.

Peter, I gave it a lot of thoughts about the success of your design from the video, and I come to the conclusion that, like tons of other models, it has to do with size. Being small and disproportionally light, your model can hover from a very low PRESSURE of cushion.
No doubt that all your trials and error about the shape of the body and of the slots have resulted in an amazing PJ HC ( and a lot of fun to fly it too!!) however if the craft would be 10 X larger and therefore 1000 X heavier, the cushion pressure would need to be 10X higher and the velocity of the Jet sealing this cushion would be incredibly greedy in power (needed power grows with the SQUARE of the air velocity).
As you know Peripheral Jets were invented before the skirt.

At a milder extend, I will encounter part of this issue with the sea scooter prototype subject of my thread. Almost every model of WIG or PARWIG I saw has a great wing surface related to its weight, and therefore flies amazingly well (and with a disproportionally low power installed). To create a single seater (so you can return to Australia after your visit to Bali) suddenly makes us jump to a total weight of 150-200 kg, while large size models of WIG I saw (almost as big) are in the 10 kg range. Quite a challenge...

To answer your question, my sea scooter will start as an electrically powered WIG, probably with some PAR needed to take off (unfortunately). Solar is the cherry on the cake to make use of the large necessary area of the wing and stabilizer, install there 30% efficiency solar panel and therefore increase the craft's time of fly much longer (and to recharge it on the waterside too). Very elegant (on paper )

I have gathered enough financial ressources to do a few prototypes, including to pay for the best electric paramotor engines and 6-10 m2 of the best wafers.
Nothing has started yet (I am till learning on several methods for the PAR rammed air, including from slots similar like yours (at the bow only).
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Old May 11, 2014, 11:50 PM
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Thanks Pascal its hard for me to ignore the realities of engineering a full size craft but i'm hopeful that scaling up the design won't involve such impossible challenges. There is also the geometrical advantage of peripheral length over cushion area to help offset the cubic weight increase.
Thats great that you have the gear organised for your project -Id like to be involved but just not possible at the moment. Please keep us updated and look forward to seeing your final design. Pk
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Old Jul 20, 2014, 04:22 AM
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Hi Peter,

I'm just back to beloved Indonesia after two months in France.

Yes, you are right, the geometrical advantage of single-dimension peripheral length over cushion area helps offset a bit the significant power increase required from the cubic weight and air velocity in the nozzle. This is assuming our full scale "magic carpets" would fly at roughly the same elevation than our models.

Talking which, I am puzzled by the way your model Hov2 manages to clear a huge cliff in your second video. By what means a model flying at 5 cm above surface can swallow a cliff 50 cm high with so little damage ??

All the best.

Pascal
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Old Jul 21, 2014, 07:12 AM
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Hi Pascal if you have a closer look at the video its just mudflats- the cliff i think you see is just a shadow, although I'm hoping the craft will eventually fly over that size obstacle with a bit more development.
Ive been doing some maths based on the original SRN1 which suggests my design would work well at that scale with approx. twice the hover height for the same power, but my aim is to develop the high speed mode in ground effect for large scale transport. Let me know when you get going on your project.
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Old Aug 20, 2014, 08:10 PM
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Peter, if I may inquire, what is the mathematical data that suggests that your design would be twice as efficient in hover height as the SRN1.
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Old Aug 24, 2014, 04:09 AM
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After trying two separate methods the results were similar but they can obviously on be a rough guide. There are a couple of reasons for the improvement - using a larger diameter lower velocity fan and a different approach to stability flow. Also theres no exact data on what percentage of air was ducted off for propulsion so i could only make a guess at about 25-30%.
-It would be good to get some details about other similar projects if anyone has had a go at it.
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