Powerin

Not sure how to work that out Tomo...I think once the full weight of the a/c is down on the tyres the friction would be the same. But I reckon there's a few factors in play with tyre wear. Firstly (using 48 and 53kts as the example) when you hit the tarmac you have to spin up the tyre 5kts faster...which *should* also require 22% more energy in this case. As you touch down there would be a short transition period as the friction went from 0-100%. During this time the energy required to spin the tyre overcomes friction and it skids...which melts a thin layer of tyre. If you need more energy to spin up the tyre I would guess you would melt more off. Secondly there's the extra tyre wear just from the extra landing roll. And don't forget your brake pads...they have to absorb that 22% extra energy. More wear there too. Remember those percentages only apply to that set of speeds. If, say, you increase you speed by 5 from 5kts up to 10kts you are increasing your energy by 400%. Double the speed = 4 times the damage (as David says above). Peter PS...Ahhh those Johnny's...always in the shop :devil:

Halfway between Wagga Wagga and Albury.

Exactly right on all counts. Peter

Hi David, Yeah...as you said it's the square of the velocity. In this particular case I used 48kts and 53kts.....53 being 12% more than 48. 48 squared=2304 and 53sq=2809 which is 22% different. The percentages would be different for different speeds. I used this calculator to double check the stopping distance and it is about 22%. You have to enter a friction coefficient between tyres and the surface into the calculator...the higher the number the better the stopping power. The site says an ideal coefficient for good car tyres on a dry surface is 0.8 but in reality it is more like 0.6 or 0.7. To get a landing roll of 238m from 48kts for the J160 I had to use a friction coefficient of 0.13 ....pretty low! I wonder are other aircraft similar? Have I driven you nuts yet? Peter

Just picking up on the 5 knot speed difference Tomo mentioned in the first post, I was curious as to the difference that would make. Working on (from the website) the J160 stall figures of Vso=48kts clean=53kts and landing roll=238m..... Landing at 53kt instead of 48kt is 12% faster, but your aircraft has 22% more energy. Meaning you need 22% more stopping distance (52 metres extra), hit things 22% harder and theoretically do 22% more damage if you do. I'm not sure if that would mean 22% more tyre wear...but it probably would. Can you tell I'm crook at home and bored? Peter

"Oh I would, Lord Dikka, if I could", lamented Jabtalker. "But she is being kept as a slave in the Palace of Jabby the Rat! (also known as the Temora RSL in these parts)", he continued. "I must steal a Natfly Shuttlecraft (bus) to get to the Palace and save her" Then Jabtalker hung his head and said quietly: "But I'm not sure I know how to drive one" "Help me powerwinKenobi....you're my only hope...."

This was all a bit too much for the newly arrived powerwinKenobe and he bravely climbed to the relative safety of the RecFlying tent roof. "Wow", he thought, "I never dreamed RAA flyins could be like this!" Munching on his freshly sauced Temora BFB hamburger he pondered over the situation. After cleverly deflecting some initial NES attacks, he now suddenly found himself a member of a powerful Triumvirate (and it was lucky he had his laptop with him so he could Google it too!). The Redeyemaster sat quietly as he plotted how he could best use this to his advantage and use a lot more smilies in his posts:sad:. Looking up he could see that DarksVader was landing a lot more LightSabre blows now that she was standing on the 3 seat cushions she always carried with her :devil:. Through the still Temora air, above the Rotax clatter, TomJabTalker's screams could be heard: "You shall NEVER convert me to the Dark's Side!!!!!.....and you're NOT ME MUM!!!!....." ------------------------------------------------------------

Shocking language indeed.....as no one had thought to describe him in that way before! The Dark One stood triumphantly over the prostrate form of Elsie, who was now laying in several pieces on the ground....sadly never to grace the pages of the NES again. A crowd had gathered and Darks swung around looking for an escape. It was lucky the LightSabre was retractable, otherwise she would have neatly sliced off BigPete's.....

Elsie was taken aback too! How could she maintain her reputation as a cougar with the Temora CWA crowd if she pursued this Toadlicker?? She looked down and saw a girl with a lightsabre and a dark expression on her face. "Young lady", Elsie whispered, "is it true what they say about this Tomo?" "Nooooo!", the dark one suddenly cried wielding her lightsabre, "I see what you want.....stay away from him!! He's my....."

...twinkle in their eyes. Meanwhile, back at the CWA tent, Elsie had been devastated by the sudden departure of O'Locks. She was lonely and had been strangely attracted to the man with the firehose and the Melbourne Bitter beercan. Then, suddenly, she spied a tall bronzed lad :face and heart:, muscles rippling in the bright Temora sunlight, holding a nice lady in one arm and a ton of bricks in the other. She tried to attract his attention but he was too busy fighting off....

.....But Elsie demmurred and after thinking long and hard about it decided soft eggs would be excellent for scones....despite the unbecoming bulge. So using all her charms she enticed the Sock man over to the CWA tent and.... Captn....your aunt is very wise, I shall tread carefully

Ahhh.... although the Powerpole's regretful entry into this eternal tale was indeed encouraged by said SockMcLocks....he now bows out in deference to the masters...lest he be forever banned from the heightened annals of YSWG

"....boiled eggs. Do you prefer yours very soft, medium or.....??"

My post above is from a theoretical point of view so probably has no practical use here. Please disregard...I was just curious. Point taken Motz and Mazda.

Hmmm...interesting. I think you are right Tomo...to get an increase in lift you must have an increase of airspeed over the wings for a given AoA. But I think you are incorrect in saying that trim maintains attitude. Instead it maintains AoA. To my mind (and this is probably getting needlessly complicated) if you increased power the speed would increase, as Tomo says, which would cause you to climb. However climbing also changes the direction of flow of air over the wings as it now has a vertical component. So your elevator's trim will pitch the a/c up to meet the air again at the trimmed AoA. I assume now that the extra power is being spent climbing rather than speeding you up any further and things balance out to roughly your previous trimmed speed? I seem to remember somewhere that if your a/c doesn't balance this out you get Phugoid oscillations?? Have to re-read about that. What I haven't read anywhere is the effect of engine thrust on the equation. When climbing and pitched up, some of your engine thrust is now pointed downwards. How much effect does this have? Is it significant compared to lift from wings? *Disclaimer*- I don't fly (except a flightsim) so all the above could be pure drivel (and probably is)

Well done Brett...nice hover!!

Well it was finally our turn this time. 4 inches (100mm) and counting for the day. Biggest rainfall day for a long long time (In my 45 years I only remember one other storm that dumped over 4 inches). Dams full and creeks flooding. Does the spirit good after 4 years of drought. I even don't mind all the fences I'll have to repair after getting washed away!!

Some of us don't I'll be driving there Saturday. Peter

That's the one I used too Tomo....only on Weatherzone (which is where where Elders get their data from). And yes Decca, the probabilities are a bit of a joke sometimes...computer generated of course. :pc strikes back:

Yeh...I wouldn't worry too much yet Tomo. Forecasts a month out are at best a rough guide. Historically our weather here in Southern NSW is very stable in early Autumn and it is our lowest average rainfall period for the year. Having said that...this seems to be shaping up to be a drought-breaking rainfall year here, and the 28 day forecast does have a high probability of rain for 2-3 April. So anything could happen! Which long term forecast were you looking at Tomo? Peter

Just thinking aloud here....there are nearly 3000 aircraft on the register, which means over 8 registration renewals every day. To keep the website expiry dates current you would need to be updating the website daily or at least weekly. It would absolutely *have* to be kept up to date, otherwise you would have people running around accusing owners of having an unregistered aircraft based on outdated info on the website. The RAAus site looks like it's a static HTML website (at the moment) perhaps put together with a website editor. Even using an HTML editor it would mean keeping track of your renewals and manually searching through the 3000 registrations listed on the website and updating 8 expiry dates every day (or nearly 60 per week). A pretty big task for an overworked paid employee let alone a volunteer webmaster. If registrations are kept on a database of some kind then it *should* be easy to get it to spit out an up-to-date HTML table of registrations and expiries every day. It would still require a person with a reasonable amount of computer know-how to generate, upload and paste in that table to the website every day. Ideally you need a database driven website that automatically updates itself from the registration database (if it exists) in real time. I dare say that might be a fairly expensive proposition for a small non-profit like RAAus? Do you think something like that is possible with the website software you are using Ian? Peter

At this stage I plan to drive to Temora for the day on Saturday. I can bring two or three 20 lt petrol containers if that's any help. I could even be persuaded to do some fuel runs for RecFly members :big_grin: Peter

From the manufacturer (Thermostasis) on another mailing list: This oil thermostat was designed for suction-side oil pump applications. It is currently ONLY approved for Rotax 912-series engines. It is NOT approved for pressure side applications like the Jabiru.

As a slogan I was thinking of "Go where eagles dare!" but I'm wondering if that's a breach of copyright? (Movie, book, song titles)

Hmmm...that sounds interesting! So where can one purchase one of those Nubile phones? :big_grin: