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I have been too quick. The idea description already mentioned this point.

To look for sounds which might become a reliable way to protect aircraft from birds is an interesting topic.

But I don't think it works for greater ditances - what it should because of the high speed of an a/c.

I have watched birds which were circled by a peregrine. As long as the peregrine was near to them, they had no panic at all and they didn't abscond.
The reason is: the peregrine is a very slow flyer when it flys horizontally.

Only when the peregrine falls from the sky vertically other birds go into a spiral descent and try to reach trees or other shelter (if they notice it soon enough).

This idea has a little problem:

birds can not hear nor produce ultrasound!

Their audible (and vocal) range is from 250 up to 4000 hertz.

That's why we can hear them twitter.

This would be a useless attempt then.

The idea of a flying car is pretty old. First concepts were designed in the 1940s & 50s. I would be interested in the major showstopers in the past? Was it only due to certification issues? Or was also the design aspect with the "morphing wing" an issue which prevented a larger market potential of those concepts?

What do you think? Will be two years for two researchers be enough for successful incubation?

Time scale and budget by Peter-TUMPeter-TUM, 17 Sep 2009 11:12

The hint with the LLC business model was very helpful. I have already integrated a link.

Questions 5 & 6 are propably too detailed for an incubation phase. Those questions, and particularly question 5 with the structural aspect might propably be answered within a mainstream funded project after a successfull incubation. The concept is primarily for passenger use. Adressing question 6 might be rather irrelevant within incubation since financial ressources are limited here.

However, we can still wait for comments from other partners and then decide if we include the additional questions.

"Criteria for succesful incubation"

Part of the LCC business model is due to faster turn around times. See for details page: [].

Suggestion for additional key questions:
5. What is the effect of using passenger containers on the aircraft take off weight and what is the sensitivity of the structure to damage (safety aspect)?
6. If the idea was only applied to freight, could this be an interesting business case and are there structural implications? Freight and passengers are commonly combined on flights.

During landing at the main a/c, the feeder aircraft will enter vortices, a very low pressure zone, because of the accelerated air above the main a/cs' wings, and thus fly jerky supersonic. At least if the relative speed is not very, very low…
So the feeder a/c must be capable of having an extremely sophisticated steering and and powerful engines to handle supersonic speeds which can occur while entering the upper wing of the main a/c in a fraction of a second.

What's worse is the supersonic boom. This loads the main a/c and all other already landed a/c a lot.
And residents will surely become "loaded", too, by the bang.

The drag and weight of the main a/c will be giantic with the feeder a/c on its wing. Remember that it must withstand crashes of feeder a/c without crashing itself.

This concept is like nice for science fiction but is it meant business?

Supersonic feeder needed by scolscol, 14 Sep 2009 13:13

It seems to me that the issues of ATM for PTS may be less on volume of vehicles than on quantity of available routes. If the idea is to design a personal air transportation concept to be compared to ground automotive transportation, then navigation flexibility (flight plan change in real time, large number of take off and landing spots, large choice of possible routes, possibly based on a network approach) will be one of its main characteristics. I guess only something like a free flight ATM could fit users needs.

This means very precise navigation means and highly reactive anticollision systems, which could mean a dual traffic control system :
-a central ATC to anticipate the use of airspace and available capacity along the different routes, and dissseminate the information to all vehicles in th area
-a local onboard navigation system, using data broadcasted on traffic density to chose and permanently reexamine the best path, supplemented by an onboard collaborative anti-collision system.

by Sebastien SylvestreSebastien Sylvestre, 23 Jul 2009 14:43

Remarks on landing of a feeder plane on a mother plane
The landing of a feeder aircraft on the flying mother plane will take place at high absolute and limited differential speed. There will be some kind of "ground effect" between the feeder and carrier plane. Suitable feeder plane control may well be arranged via a vertical control system implemented in the wings of the feeder aircraft. After landing, the feeder plane will probably to be locked to the mother plane.
The transfer of passenger and luggage needs to be under controlled atmospheric conditions (at 10 km height). This suggests an air tight docking(/locking) system.
Take-off will probably be more complex from a flying / control point of view. A feasibility study on the aerodynamics of the process will probably be needed.

Re: Airborne Metro by SiteManagerSiteManager, 08 Jul 2009 10:20

You may have a look at the iFly-website for back ground information.

iFly is a specific targeted research project within the 6th Framework Programme FP6-2005-Aero-4 (Priority Aeronautics and Space), funded by the European Commission under contract number TREN/07/FP6AE/S07.71574/037180.

1. One of the areas that receives little publicity in the planning of future personal transport systems is volume. How many of these things are going to be using the airspace at one time. Experiments concentrate upo9n getting one vehicle to perform but seldom do we hear about how it will be when 10 or 100 or 1000 are aloft in close proximity. What are the challenges that this facet will bring?

2. Let's try some numbers. There are about 20 million road vehicles in the UK that transport around 60 million people. This averages around 1 vehicle for 3 people. These will not be uniformly distributed but let us assume that they are. If Greater London (metro city) is a city of around 10 million and has an area of about 2,250 sq km. This provides a density of moror vehicles of around 3,300,000 vehicles or about 1500 vehicles per sq km today.

3. Let's assume that with the availability of PTS there will be a transfer of travel to the extent of 10% - not an impossibly high figure maybe. This implies an ownership density of about 150 per sq km. Not all of these will be in use at any one time so let's assume that perhaps only 10% could be used simultaneously or 15 per sq km.

4. 15 PTS in use per sq km is a very much higher density than any other form of air travel. They will not be uniformly distributed and will cluster around the entry and exit routes. So an residential area of maybe 10 sq km could produce 150 PTS all heading into London along a relatively narrow corridor at one time - and of course picking up other users as they go.

5. If we take a single vector into London that is a triangle of angle about 1/10th of the arc around the city this equates to 10% of the London vehicles or 330,000 or about 33,000 PTS of which we are considering 10% being in use say 3,300. So another way of looking at it is to imagine over 3000 PTS approaching London along a single vector over a single time period.

6. How do we stop them crashing, colliding, breaking down or interfering with other traffic. It seems to me that if the vehicle is simple to operate (which is always the aim) then they must be controlled by computer systems. With the growing power of computers it ought not to be insuperable to provide a navigation system that not only controls the route between inserted points but also performs the sense and avoid role for inter-PTS collisions. This may need to be combined with an on-board radar system such as is already beiing develp[ed for road vehicles.

7. These control systems would need to be duplex fitted or perhaps even triplex to give high levels of assurance of serviceability. The maximum height would be controlled and areas of "NO GO" would be pre-imprinted into the flight computers. "Flying" this kind of PTS would be about as complicated as setting your car's navigator. Dial in the destination - press GO and everything subsequently is automatic. The take off would be after a series of computer driven checks - the initial heading would be set and the avoidance plan would kick in to manage the flight in speed, heading and height to avoid fixed and moving obstacles and prohibited areas - the fixed data would be just that and the transient data provided by the collision avoidance radar would allow variatioins of speed, height and heading to allow safe passage.

The basic concept has been articulated but we don't seem to be progressing the challenges within it very quickly and I thought I would set out the pros and cons of some aspects as I see them.

1. Getting the cruisers into the air. If the concept is to work it assumes that the cruiser will be a very large aircraft and we need to start with some assumptions. Let us hypothesise that it is a 2000 seat cruiser. If we take some sort of payload proportion and extrapolate to a 2000 seat aircraft we might end up with a an MTOW aircraft around 2000 tonnes. Refining this will depend on many factors but let us assume this figure temporarily. Getting it airborne might be best achieved at a lowest safe operating weight i.e. with no passengers and minimum fuel and this would reduce the weight by about 400 tonnes or more. It would also be very large with a wingspan perhaps around 1.5 times the A380 if of similar configuration , say 1.3 for a BWB which might indicate circa 100-110 metres unless its cruising role indicated higher aspect ratio wings which might send this up to maybe 140 metres.

T/O would, of course, require more power than cruising and there is room for some further innovation in working out how the extra weight of of propulsion can be reduced after it is "on station". Could it be enabled by fitting dischargable rocket boosters, or jettisonable engines, or even having another large aircraft tow it on T/O? How would this work in practical terms?

2. The propulsion system: early thoughts turned to nuclear power - this was tried in the 1950's and has more recently been tried again by the USA/NASA. It seems that the weight of the power plant can be got down to feasible levels (below 80 tonnes) but the issues of perception, risk, system failure, shielding etc still remain largely unsolved. How could these challenges be addressed on a very large aircraft like the cruiser? Its size would allow some extra flexibility but the size is not very greatly more than an A380 - would this have a major influence? Could the design of the a/c be approached in a new way to allow a greater barrier of distance or shielding to be accomodated? It seems superficially quite hard to do this for a large civil aircraft without undermining its whole design concept. Could the weight of the reactor, though admissible in simple weight terms, be arranged to be at a less diffiuclt place than close to the CG? It doesn't immediately seem very feasible but what do the weights actually look like?

3. Non-nuclear power: Really drives the solution to be a similar concept to present day high thrust turbo-fans. By careful design it might be possible to configure a VLA of this type to be economical at a lower speed than the 0.82M that we have become accostomed to and let in the design of turbo-prop cruising engines to the consideration. What would be the fuel consumption of an economical large aircraft of this kind be? How much fuel would it be economical to carry between air-refueliing? How would the cost of the fuel carried be offset against the cost of re-fuelling and optimised? What is likely to be the driver of lifetime return on capital employed?

4. The concept relies upon smaller feeder aircraft "joining" the cruiser but how this might be achieved has not been much studied. The economics of cruiser operation suggest that it should not vary its speed by very much so the feeder aircraft could dock if the speeds were aligned - how should they dock. The vortex flow over the wing of such a large aircraft as the cruiser could be damaging to an aircraft perhaps a tenth of its weight. In which direction shoudl the feeder approach the cruiser and what mechanism of docking should be provided. How should the final few metres of the relative distance be managed - the feeder would need to adjust speed, height above the cruiser, lateral position and to do this within both the turbulence of the cruiser and the natural weather turbulence. Could the feeder fly into a catching latch that once secure would wind the feeder up or down into the cruiser main dock? If the cruiser was a BWB could the feeder approach from behind and above and enter the high speed airstream over the upper wing accelerating to set down on a docking platform. There seems to be a handling problem analagous to flight refuelling that if the feeder goes out of the "tube" it immediately finds itself flying too fast or too slowly.

Airborne Metro by Trevor TrumanTrevor Truman, 06 Jul 2009 19:16

2 July 2009

This short message is meant to check the functionality of the discuss-option at the bottom of each page.

SRA2 Volume 2 provides tables to link the Sectors (3), Areas (10), Domains (Many) and Technologies (More !) of the Taxonomy.

The technology column provides titles for new pages to be setup as "under construction" pages and later be developped by Innopedia users (Wikipedia has many of these pages with just a title, as an invitation to start working on it…e.g.:

I should be able to provide the electronic version of SRA2 so that we can easily capture that column. I think it would be a good basis to have at least some of these "technology" pages open, ready to be filled in by people with ideas !

Re: Taxonomy by Sebastien SylvestreSebastien Sylvestre, 04 May 2009 15:47

Hi all,

This is indeed a very good idea to add that discussion option at the bottom of the pages, thank you Guy.

For that page, I suggest we just summarize it to a very very short presentation of each solution, with the link to the comprehensive page (which already exists).
That way we will avoid having the same text on two different pages !

Adding some lines on what lies behind the systems of systems concept may also be a good idea.

Do you agree ?

Split the page by Sebastien SylvestreSebastien Sylvestre, 04 May 2009 14:51

It is suggested to add the ACARE (ASTERA) Taxonomy [definition Wikipedia] to the side (as a prominent item) and use tag-words to fill the tag cloud.
It will then be easy to use the search function of the site to find each tag reference back as well as the remaining information on the tagged item.

Any comments, advice?

Taxonomy by SiteManagerSiteManager, 04 May 2009 11:53

In fact it appears that some of the Systems-ideas pages already exist with a single idea, but this means there is a text redundance, since the same text is displayed on the systems-ideas page and on each page dedicated to one of these ideas. This could lead to modifications done on one while the other does not change…

Is there already a plan to split the compiled page and then delete it ?

Good morning all,

I think the Out of the Box "System ideas", "System of systems ideas" and maybe even "subordinate concepts" are too long as they are.

Shorter pages will invite members to complete, add links, complementary information or graphics, whereas long pages are discouraging.

Could we split these pages into one page per "idea" ? I can spend some time doing it if you agree with the principle.

Sebastien, ASD

This is a reply to "Trail thread".

Re: Trial thread by SiteManagerSiteManager, 27 Jan 2009 12:32
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