APenNameAndThatA

I think it is a great idea. There is only going to be clutter where it would be better to use a VNC. Furthermore, around Alice Springs, there are areas of layer cake that are not on a VTC or VNC. Next, they need to add the boundaries for Class G and Class E frequencies. 

On 2/10/2022 at 8:42 PM, BrendAn said:

Off on another tangent now.

Why when I read aircraft specs is neg g is always lower than positive g in the airframe stress limits. 

Probably a dumb question but I don't know the answer.

 

The positive number needs to be higher. When you are flying along, you are at 1G, not zero G. Most GA manoeuvres, like turning, add positive G's rather than result in negative G's. Aerobatic planes have more even positive and negative G's. 

12 hours ago, BrendAn said:

How can U not understand friction 

Well, I’m happy to be corrected. From time to time I post about mistakes that I’ve made. My view is that if a propeller hub is functioning correctly, the friction will be such that there will be no movement between the propeller and the hub and therefore no heat generated. 

Quick google search… “There are two main types of friction: static and kinetic, according to the journal The Physics Teacher (opens in new tab). Static friction operates between two surfaces that aren't moving relative to each other, while kinetic friction acts between objects in motion.”

So, what I’m saying is that with properly designed and functioning prop hubs there is static friction, and certainly not enough kinetic friction to heat up the whole hub. 

To loop back to what turbo said, if a prop hub is correctly designed and functioning, it will be clamped sufficiently that there is static friction and not kinetic friction. 

13 hours ago, old man emu said:

I missed that source of vibration. I was thinking of the propeller producing Lift longitudinally. All other things being equal, the amount of Lift is dependent on air density. What happens when a plane flies through an "air pocket"? Air density decreases; Lift decreases and the plane moves away from its steady state path. Then it flies out of the "air pocket", air becomes denser and Lift increases. 

 

Apply that thought to the propeller at the same time. It seems logical that going through the changes in air density would result in changes in the Lift (i.e. Thrust) forces it creates. Surely that must induce fore and aft vibration that expresses itself at the Boss/hub interface as rubbing. And rubbing induces heat.

Turbulence is caused by variation in air velocity, not variation in air density. It might be that that misunderstanding would be decreased if people stopped talking about air pockets.  

If aircraft sank when they flew into less dense air, then they would sink when they flew into thermals of rising air. Air in thermals is hotter and therefore less dense than surrounding air. 

15 hours ago, Bruce Tuncks said:

yes it would if there is any movement permitted. The slightest looseness, which is not discernible on the ground, will provide the relative motion and energy = force times distance . The energy from this friction will become heat.

This is what caused the prop hub to go burnt black on our first Jabiru.

I reckon we were lucky in that the flywheel bolts stayed good. The lesson is...  Make sure your prop is on tight, and as I said, an indicator blob will help. The dried blob will crack if there is relative movement.

That is an abnormal situation. I’ll take your word for the blackness occurring because of heat, but I would have thought that any blackness would have occurred because of mechanical wear, not due to heat. 

The idea that two pieces of metal could be fixed to each other and move about enough against each other to cause heating just amazes me. I have never heard of such a thing. 

I am far from an expert, but I would start by asking the manufacturer. It might be that they approve bigger wheels. It might also be that they tested with bigger wheels and can tell you what happened.  

3 minutes ago, Bruce Tuncks said:

OME had it right. The variations in rotational speed come primarily from the pulsations from the power strokes. 4 cylinders are worse than 6. The worst I have ever come across was a single cylinder 4 stroke model plane engine. Just imagine...  power for every 45 degrees in 720 degrees.

Apparently with high-speed photos, you could see the prop bent one way on the power strokes and (less so ) the other way for the rest of the cycle.

Here, the prop acted as the flywheel. It sure would on a big plane engine too.

But does that heat up the hub? 

29 minutes ago, old man emu said:

Isaiah 55:8-9

In the past, you have said that your theories were better than Einsteins because your theories could be tested. This is a new high. Congratulations. 

That’s actually a good question. Probably the aircraft with the best instructor, or the aircraft that will best fit your mission. Time in type is good to build up. 

7 hours ago, old man emu said:

Stands to reason. The bolts are pulling the prop boss and hub together by creating forces acting in a longitudinal direction. At the same time there is that transverse force created by the rotation of the propellers matter. Over the length of time that the engine is running, per flight, minor variations in the speed of rotation can cause microscopic amounts of movement between the propeller boss and the hub. That little bit of "rubbing" creates the heat that facthunter has mentioned.

That sounds ludicrous, but it you can provide a reference of some sort I’ll stand corrected. 

8 hours ago, turboplanner said:

Unbrako is just a brand; for this safety-related item you need a specification from the manufacturer.

That was the problem. The specification was written on top of the bolt but it wasn’t true. Sure, 8.8 and 8 bolts are different, but they’re not that different. And nobody is going to break a high tensile bolt by over torquing it attaching their propeller. 

The latest message from RA-Aus contained this gem.

"This weekend I was supposed to fly out to William Creek. Something I have been so looking forward to for months. My plane is literally packed, fuelled and ready to go. I’ve been watching the weather for a week or two, watching trends, looking at the entire route, effect of weather on diversion airports etc. On Wednesday I made the call to not go because the weather in Canberra was going to be marginal for my departure on Thursday morning and there are also very strong winds forecast for my departure from William Creek on Sunday. When looking at the trip in a systematic way, consulting aviator friends and colleagues, identifying threats, and weighing up risk vs reward, I’m comfortable that this is the right decision for me."

The problems here, that I can identify are as follows.

a) There was no reference to written personal minimums. Personal minimums are written in knots, feet, metres, minutes and octas. "Marginal" and "very strong" are not proper ways of making go/no-go decisions. 

b) He should have checked the weather on Thursday morning, not on Wednesday day. 

c) About weighing up risk and reward, my understanding is that the when the RFDS decide if they can make a flight or not, the pilots are not told if the trip is an emergency or routine. They have a deliberate policy of not considering risk and reward. To be fair, I have different minimums for flying alone and with my family. 

Then, there was this gem. 

The U.S. Federal Aviation Administration (FAA) defines aeronautical decision making (ADM) as “a systematic approach to the mental process used by aircraft pilots to consistently determine the best course of action in response to a given set of circumstances” (FAA Advisory Circular 60-22). I ask you all to apply a systematic approach to decision making, to weigh up risks and take the time you need to make good decisions so you do come home to your family and friends. There is a wealth of information on Aviation Decision Making including the abovementioned Advisory Circular and this article provided through SKYbrary.aero  by the Flight Safety Foundation. 

The link was to here https://skybrary.aero/articles/decision-making-training-oghfa-bn. The article guilty of my pet hate: not being concrete and specific AND not so abstract that it gives some overall insight. Instead, it provides a middling level of abstraction, talking about things, rather than actually saying what they are. 

Then, there was this, also a gem. 

When I started in this role back in January 2021, it was midway through COVID-19 and La Nina hadn’t yet arrived on the East Coast. The result being that from September 2020 until May 2022 there were no fatal accidents – a record we were very proud of. We’ve now had four accidents where four RAAus members have lost their lives since May.

There is no recognition of random variation and regression to the mean. If COVID and La Nina were so obviously the cause of these things, then it would have been possible to predict that there would not have been fatalities during lockdown and that there there would be a spike after May. Nobody made the prediction, for obvious reasons. Sheesh. 

Lastly, "preempt" doe not mean what he said it does. To be fair, this is the new usage. 

20 hours ago, old man emu said:

I need some feedback on this Rule for the Event. The liability of the Organisers needs to be protected. Will RULE 3.3 cause an interested participant to have to give the event a miss?

RULE 3.2

The pilot-in-command nominated on the entry form will be required to produce for the

scrutineers:

(e) Evidence of insurance cover in accordance with the requirements of paragraph 3.3 of these rules

 

RULE 3.3

The evidence of insurance cover as required by Rule 3.2 (e) shall take the following form:

An endorsement note from the aircraft's insurance company which states that its Third

Party and Passenger Liability insurance (in respect of that aircraft):

1.     Has been extended to include the Arthur Butler Trophy Event, and

2.     Has been endorsed to include as the insured the organisers, Arthur Butler Aviation Museum Inc., for their respective rights, interests, and liabilities under that policy, and

3.     The sum assured shall be a be a minimum sum of $5,000,000 for Third Party and

$5,000,000 for Passenger Liability.

4.     The policy must insure the entrant, crew, passengers and those persons representatives and employers against liability arising out of the participation in this event in respect of such persons and the aircraft.

All entrants should contact their own broker or underwriter with whom the aircraft is normally insured to ensure that the requirements of these rules are complied with prior to the commencement of the event.

 

If some part of it causes a problem, which part and why.

 

Thanks

That sounds problematic. I can't imagine an insurance company signing up to insure people they have never heard of for God know what. Probs best if you organise your own insurance and pass the cost on to the entrants. Disclaimer: I have no experience of this. 

On 20/9/2022 at 8:02 PM, Bosi72 said:

Hi Matt

 

I feel devastated at this moment after reading the news and connecting the dots, especially for not encouraging you more to study and learn as much as you can.

 

After getting a PPL, I still felt a big gap in my aviation knowledge, therefore I've decided to read, and my first book was CPL Meteorology. Because this was the area which I wanted to learn more about, and to know what to expect/avoid when flying for fun.

 

As we all know, passing an exam, or getting a licence is only a "licence to learn", because we are living in ever changing environment. Therefore learning never stops.

 

I hope this post will encourage fellow pilots to learn more.

 

Rest in peace my aviation friend 😞

 

 

 

 

 

 

Which one did you read? 

I suspect Walrus and Onetrack are both right. 

On 4/9/2022 at 11:44 AM, Markdun said:

Found the knocking culprit. The main shaft that rotates in the plastic bushed aluminium pillow blocks bolted to the firewall. Rotates smoothly but there is about 1mm end float so the whole front wheel assembly (except for the pillow blocks bolted to the firewall) will go up and down 1mm as load is applied and removed which happens when the nose comes down after you hit a bump.  With a fast taxi I couldn’t notice it.... mainly because the whole plane rattles.  I’m still trying real hard to understand why ppl prefer noise wheelers instead of conventional.

The tail wheel pilots’ superior skill fails to compensate for their poor choice of aircraft, and they crash more than tricycle pilots on taking off and landing. That’s no joke. 

On 28/8/2022 at 2:00 PM, Markdun said:

Ehhhh? When I did the conversion to nose wheel the instructor said to me as we were slowing down and about to turn off the runway (bitumen) that 'its ok for you to lower the nose wheel to the ground gently now'.  So if a nose wheel isn't for taxiing what exactly is its function; perhaps the same as a rubber duck?

I was mostly joking. 

7 hours ago, Flying Binghi said:

Go find an aerobatics flight school and do a few hours. Many questions answered..🙂

 

 

 

 

.

I have done a few hours aerobatics. 

The back and forth might be hiding an important question, IMHO. If you have an engine failure on takeoff or accidentally find yourself stalling turning final, do you a) adopt a glide attitude or b) quickly get the nose at least 10 degrees below the horizon? I favour the latter, big time, but Ive got a massive 212 hrs. 

16 hours ago, Yenn said:

Typical of Australia we purchase an in development aircraft and then contribute billions to an unknown performer. Just have to hope it will work.

The Sydney Opera House and F111 both were over budget and disliked at the time, but they worked out okay. But, it would be reassuring to buy stuff off the rack, as it were. 

1 hour ago, Roundsounds said:

You were concerned about speed being less than Vy, that’d be an IAS?

Stalling has nothing to do with IAS, angle of attack dictates when a wing will stall.

Okay, we’ve put the issue of lag to one side. It is true that stalling is determined by AOA. But it is obviously incorrect to say that airspeed has *nothing* to do with stalling. That’s how come aircraft have a published stall speed. Yes, you can stall at any speed (unless the plane breaks first) but Im pretty sure you’d agree that the lower the airspeed the more likely a stall?. I was obviously addressing the issue of AOA by referring to the sight picture, the pitch of the aircraft. 

Anyway, is there anything that I’ve said that is incorrect? 

With GPS, Im not sure how you’d run an air race these days. Back in the old days, you were supposed to limit throttle and people were supposed to check fuel usage. 

I believe in global warming, but attributing extreme events to it is nonsense. For example, the Brisbane flood of 1893 was way bigger than the 1974 floods. If Cyclone Tracey and the Bris 1974 floods happened today, they would be taken as PROOF of global warming. 

On 30/8/2022 at 8:22 PM, pmccarthy said:

I have found most people on this site have been converted to the warmist religion.

Through their religious faith, pious sea monks have opened new shipping lanes in the Arctic. ✝️  

On 30/8/2022 at 1:02 PM, onetrack said:

In the weight and speed class that Jackc is flying in, would it really hurt to incur a forced landing when the fan stopped? Seems to me the chances of structural failure in a microlight are higher than the engine failure scenario.

Yes.