Geoff_H

Landing gear support. Green is proof of design, it was too small and was increased. White part should have been a straight nylon part, it failed impact testing

Pictures show printer with water cooler left. Also the water cooled nozzle and some nylon parts manufactured.

I have designed my aircraft to use 3d printed parts for all load bearing parts except where elevated temperatures are involved. I have used AutoCAD to design the parts. I bought a Leapfrog Create HS. I paid $2.5k when the dollar was much higher, the printer has some serious problems when one tries to print nylon. All bushes in my aircraft are nylon, all load bearing parts are nylon impregnated with carbon. The design of these parts is very different to the conventional steel parts. They are built a but like internal house doors, a honeycomb on the inside and a thin shell on the outside. Nylon and carbon impregnated nylon are around one sixth the weight of Steel, half that of aluminium. I have had to modify the printer that I bought, it now has water cooled nozzles, an aluminium print bed, special nozzle feed (I have developed a nozzle capable of temperatures of hundreds of degrees centigrade) I print at 265 degree Celsius. I have built a temperature controlled enclosure. I am printing the wheel hubs, Azusa injection mould their wheels using the carbon impregnated nylon. They work well. I impact test each print, every now and then I get a layer that didn't weld to the layer below, once because I opened the enclosure to have a detailed look while printing. The parts have been conservatively designed. The purpose of the aircraft is to confirm that a lighter aircraft can be built by this method. I am thinking about designing the flaps using the 3d printer. Experiments with nylon alone showed them to be the same weight as fibreglass flaps and not nearly as rigid.

Can I put my own designed aircraft in RAA? At this stage I intend to be in Experimental GA. But with building problems (using 3d printed parts extensively), it may not be finished for several years, I may have lost my Class 2 by then and need to go to RAA.

Yes I noted them too. They are making non loaded items, and devices. I am modifying a 3d printer to print nylon that is strongly bonded. Having heaps of problems but am getting there, nozzle wear is the next problem I have to solve.

Did anybody see the recent article going around about the 3D printed aircraft. parts of my designed aircraft will have printed parts in load bearing areas. Has anybody on this site made load bearing parts for aircraft? If so what experiences have you had?

It certainly went 270degrees. Yes you could counteract it if you could discover the stuck brake in less than a second. Took me some time after the craft stopped. It was kinda frightening.

I would not say that tricycle gear cannot ground loop! Did it when a brake stuck on! Anything will ground loop if the resultant drag forces produce a moment offset from the centre of gravity

Just did my Class 2 with a DAME. Cost me $50 less than a basic class 2. And I can again fly at night and do aerobatics. I only had one examination, not one with an optometrist and one from a doctor. Won't do the Basic Class 2 again.

I have lived under the Lane North of you for over 35 years. I've seen quite a few aircraft coming Southbound in that Lane I also questioned it some years ago and I think the answer I got was that's an advisory Lane not compulsory that someone else might be able to confirm that. Personally I wouldn't go South in it

Around 10 years ago a group of us on the Mooney Australia web site were planning go to NZ. The guys that did the planning suggested that we would be up for a couple of grand each, singly I would expect more. A visit to their website may find the person that knows what to y.

I rented out my first aircraft, it cost me a fortune in damages cleaning etc. My Mooney was only ever flown by me when I owned it. I am so glad that I did not rent it. Same with my house when I rented it out. Only once!

No toe out will help taidraggers. Race cars use it as it responds quicker. Also consider that the C of g is in front of the wheels. A drag to the off side will pull the craft the other way correcting the off course deviation. Toe out on tricycle craft will make the off track worse. It is all in where the C of G sits. All forces produce moments about the C of G.

I believe that the toe in/out depends upon whether the craft is a tricycle or tail wheel. In a tail wheel the C of g is Infront of the wheels, this is critically stable and can lead to instability very easily. I understand that on a tail dragger toe out is better as it acts quicker and pulls the craft back to a more straight line during landing. Landing is where stability is critical, taxying can be less important and whilst annoying I think that most manufacturers look to landing characteristics. Tricycle craft have the C of g in front of the wheels, somewhat more stable arrangement for landing. It is my understanding that manufacturers will arrange toe in/out on tricycle craft so that from touchdown to relatively slow motion that the wheels are close to zero toe in/out. The toe in/out at this point of relatively low loading depends on the way the undercarriage moves with camber and caster and forward alignment during the process of undercarriage loading. I think that as you can only adjust the undercarriage alignment during stationary but light to medium loading is critical then it is trial and error, unless you have a finite element program and lots of time to calculate a variety of options, and of course springs vary so much that you would have to test the spring rate. I have no idea what your friends problem is caused by, I suspect spring geometry or an undercarriage wear problem or change from original, but if one craft behaves differently to another of the same make and model I would carefully examine the whole system including location to the frame of the craft.

Oct 15, 2018 New #48 "Geoff_H, were you referring to the Navier-Stokes equations? They have been around for years longer than you said. And incomprehensible to us poor mortals." The way I understand it the first solution of the Napier stoke equations for ships hulls was done in 1896. I think that it was a mathematical solution to the differential equations. I think, but not sure, that it was using a froude number maybe in three dimensions

The most interesting story that I was told about aviation mathematics was told in 1970 when I was at Uni. Early in the 20th Century (around 1915) aeronautical were working on the mathematics of fluid flow around a solid body, they were so proud of themselves determining all the mathematics using first principles and then published their research only to be informed by naval architects that they had developed the mathematics 20 years before. L ack of communications!

For my money both are exactly the same. An object produces a force equal to the mass change in momentum that it causes to the air, or fluid if we are talking about boat props. But try and work out the lift using the change in flow. To theoretically work out lift use the Dell operator around the wing. Very complex mathematics. However Bernoulli's theorem with a lot of factors to make a single instance of the equation work and you have the most appropriate equations work. There is a website that offers a two dimensional solution using the Dell operator mathematics. But even that is approximate, the three dimensions makes it much more difficult. I did three years of university mathematics and four years of engineering nearly 50 years ago and so the Dell operator is just a faint memory. 20 years ago I got the old books out. I was totally lost in how to do the mathematics. I just use the Bernoulli's equations with correction factors determined by wind tunnel testing.

I wish that I had never made the throwaway comment about the possible lack of need lot pilots in the future. I was seriously trying to find out if there was a genuine upturn in people wanting a ppl. A friend of mine was asked to buy an aircraft and put it on line to make money. Basis of the request was that he could expect 400 hours per year of hiring. Any comments

I worked in super reliable control systems. The first 4 Airbus crashes were a result pilots overriding the control systems. Now Airbus have many actions that are cannot override. Accidents in Airbus aircraft are very rare. When we design superstars control systems we look at the reliability of each individual "control system" usually ifr something is too hot we measure with 2 to 4 temperature devices and use 1 to 4 devices to regulate the temperature. A solenoid may have been tested and failed 1 in every 10,000 operations. We multiply all systems out to get a probability of failure that the systems cannot control . For human travel these systems have to be greater than 1 in a million hours. Why is this relavent? When the control device is a human, the probability is 1 in 2! With excellent training, like I am sure that you provide, it is much better, but no where near the safety figure offered by multiple redundant control systems. I have now retired but 45 years in the control industry have seen me not wanting people's jobs taken by control systems. I don't think that we as humans are going to cope with a lack of purpose . Unfortunately the economics of peopleless machines will win out when big business are just after profits. Who would ever the banks would be like they are today because of automation.

I expect bus drivers employment will be o lot less than 20 years. Bus and truck drivers are the source of money making driverless cars. Airline pilots are only there to make frightened passengers feel safe lol

I have had a report that there has been a large upturn in the demand for GA pilots licence. Has anyone else heard this? I suppose as the airlines are having a demand. Personally I expect pilotless aircraft in around 20 years I wonder if an airlines job has so much future.

Point taken. I don't know what other words to use

I could not agree more. The expense that made the cost around double was that my doctor was not equipped to test my eyes. She asked me to go to an optometrist. The optometrist charged $160 for an eye examination for a heavy vehicle licence. I have a licence that the medical does not all ifr flying, no endorsement so no worries . No night flying, well I think that my night vision is not as good when one gets older, so not really an issue. Biggie is aerobatic flying. Something I was about to start, but next year I can do a dame exam and then get all privileges back.

Sorry, just read profile. I see that you are in Great Britain. Age is getting to me lol

Where are you located?