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On 28/9/2020 at 11:43 AM, SSCBD said:

FT A lot of CSU's are being fitted to RAA  LSA aircraft these days specifically with Rotax engines. My Question is why I cant see any on GEN4 engines. 

And as I stated - the performance increase Quoted by  - Airmaster Propellers CSU state that:

 

Performance tests have shown up to:

• 33% shorter ground roll

• 10% better climb than fixed pitch prop

• 20% improvement in cruise and economy

Also provided was an Endorsement Specifically  J430 which is the 4 seat VH version

 

Sohrab Ghasimi - Jabiru J430There were some significant improvements in performance as follows: 20-30% reduction in ground roll, Higher climb rate, Smoother running and an increase of cruise speed to of 15 - 20%.

PDF from Airmaster of above information.

http://www.gap.aero/pdf/airmaster/Airmaster_propeller-systems-332-420.pdf

 

 

SO if you operate in say far nth QLD and tight strips in a Jab 230 for example - and you had the money WHY NOT Have the extra performance. 

 

 

 

 

I think that if a CS prop actually gave a 33% shorter ground roll AND a 20% improvement in cruise then you would get much less argument from people. I bet the performance improvement would be nowhere near that good. I think the disconnect in the convo is that no one believes those figures.   

To get a 20% improvement in cruise, you need to effectively have 1.73 times more power. I the efficiency of your standard prop is 0.6, then that is not possible. IIRC, the average prop has an efficiency of 0.8. (By efficency, I mean converting engine power to prop power/work. (1.2 cubed = 1.73)

(As for the mighty Foxbat: revs just below yellow on takeoff and just below yellow full throttle at 8000 ft cruise!) 

4 minutes ago, Bruce Tuncks said:

I've never had a forced landing in powered planes so I'm grateful for this discussion.  As a weight-saving fanatic, I would like to know the total weight of the setups described though.. That is why I liked Nev's thing about plastic bags and Old K's ides about the cd disc mirror. Negligible weight with these items.

Personally, I carry a plb because I thought it was compulsory.

It is *generally* accepted that the mass of 1 L of water is 1 kg. Everything else is pretty light. I can’t see myself carrying a jack but Im not saying that it is wrong. 

The easiest thing to do would be to donit the old way and the new way, and gradually change over. I use Ozrunways. It would probably be best ti use to app your friends use. Also, consider the size iPad you want. I use an iPad mini and it stays up out of the sun, over the passenger’s head, on the right wingroot. Most I see are much bigger.

iPads are worth using because they speed up incorporating winds and weather into your plan immediately before you take off. You input the plan in advance, and then incorporate the winds and etc just before you take off.  

1 hour ago, sfGnome said:

…or you hotspot it off your phone. Saves paying for two SIM plans

(But you still need an iPad that gas GPS, which means it needs to be capable of data downloads, IIRC) 

On 30/6/2022 at 10:19 PM, jackc said:

Your motor won’t blow up IF you get a negative answer 🙂Just fly the freaking thing 🙂 

You might, and might not, want to check with your insurer. 

23 hours ago, johnm said:

this one should give you power line mapping 

 

give you an idea anyway

 

https://www.arcgis.com/apps/webappviewer/index.html?id=5a53f6f37db84158930f9909e4d30286

Post of the week. I didn’t know about the powerlines beneath the southern circuit at Archerfield! I suggest you start a new thread to let everyone know about the app.  

4 hours ago, Old Koreelah said:

With our very light little aeroplanes landing on soft ground, it’s tempting to run low pressure in the tyre; too low and that may risk tyre/tube creep and damage to the stem.

How low is too low? 

What do you all think of x

canisters of tyre inflation goo vs carrying spare tubes and etc?  

11 hours ago, danny_galaga said:

I'm going more minimal. Each tube is 1.2 kg sou will carry a patch kit, which I'll replace every year. I think the CO2 cartridges that the mountain bike guys use will be lighter than a pump but I'll weigh it all. What does your neck consist of? I think I can make one from a spare Ali tube left over from the build. There's a rather handy lug near the undercarriage that doesn't seem to be used for anything so I'll make the jack for that 🙂

What is a neck? 

Like someone else said, email rather than phone, so you have it in writing, IMHO. 

Survival gear and repair gear are two different things, of course. I am very happy for both things to be discussed in the same thread. The only repair-ish things I carry are Leatherman multitool, small shifting spanner, type pressure gauge, small right-angle extension so I can get to the valve stem when inflating, tyre inflation air and puncture repair goo in an aerosol can, 2 m tape measure, tie down ropes, ground anchors, drill bit to get the ground anchors in, ratchet to rotate ground anchors, 1 L oil, duct tape (for fabric control surfaces), some weird tape that sticks to itself (very light), cord, fuses, and microfibre cloth for the windscreen. Disclaimer: I have only 185 hrs and would probably wreck a tube if I tried to repair it. 

55 minutes ago, farri said:

I posted this believing the information I had was correct! I`ve done more research and it turns out it wasn`t! I sincerely apologize...Another lesson learned.

Franco.

 

I thought what you did was reasonable. 

That airline name did not age well. 

3 hours ago, old man emu said:

Here is the original question:

The first modifier was that your Desired Track had did not involve a full-on headwind, or maybe there was a tailwind component.

The first error I made in posing the question was to write " looking for a place to land". If you delete those words, I believe it clarifies the point of the question and directs discussion towards the point being enquired about - does the direction of unpowered flight with reference to wind direction affect the TIME it takes for an aircraft to lose altitude?

 

The discussion then turned to "ranging", which, if I'm correct, is related to Ground Speed, not Airspeed. 

 

The question of altitude loss in turns was also brought up. Perhaps the words "swing around" were a poor choice, implying something like a split-arsed turn. As Thruster88 has shown above, one can make a gentle turn without significant increase in load factor that would require increased air speed to overcome. From his graph, an angle of bank of about 20 degrees make a relatively insignificant increase in load factor.

 

Finally, the words "while you search for a place to put down?" could have caught another red herring. The initial need when this unexpected event occurs would be time to think and decide on which course of action to take. Wouldn't the first step be to try to determine why the windmill stopped? Maybe getting it spinning again could be as simple as changing tanks.

 

Robinsm said, I would have thought that the best effort would be put into finding a convenient landing spot and concentrating on that, not recalling master of physics lessons  Identifying situations and developing procedures to minimise them are the basic steps in Risk Management. Better to learn the procedures well before they might need to be used, than trying to reinvent the wheel in the middle of a situation. Isn't that what ground schooling is all about?

 

Finally, I posed the question for the simple reason that I didn't know the answer. Isn't what this particular section of the Forum is all about? I was not trying to be didactic. If I posed further questions it was because the replies while correct of themselves, were not dealing with the point of my enquiry.

 

I'm sorry if that sometimes I ask for calculations to be shown. Everyone learns in their own way. The meaning of some words can be subjective, while hard, cold numbers can only be objective. I happen to be a person who needs the objective.

You posted the question because you did not know the answer? Really? Is that how come you argued with the replies? 😆

On 29/1/2022 at 7:29 PM, RFguy said:

Hi SKippy

As I continue to learn about fluid dynamics, some things are now apparent by the numbers...

firstly - 

For liquid cooled aircraft,  using the surface of the leading edges of the aircraft, like using tube forming the wing leading edges,  or the skins being heat exchangers would be fantastic for liquid cooling, and wouldnt require any front area dedicated for cooling... seems a no brainer, but I have not seen anyone doing it.  

 

The leading edge would seem a no brainer, and some aircraft I think the RANS the leading edge is already an alumuminium extrusion. 

The skins, while that only receive boundary airflow (lower velocity etc) , large areas available would make them work !

If I replaced my Jabiru top or bottom cowling with a skin of aluminium with water in behind it, like a flow structure etc (there are many flat, formable aluminium extrusions designed  for intercoolers etc )  , there would be more than enough surface to cool anything.... I dont have time to weld up the tanks on each side of the flat tubes so I'll use draggy radiators.. 

 

Now the bad news :

 

Your small inlet  (suggest min 288cm2) , large  plenum (the cowling) is akin to a hydraulic  amplification.  small  inlet into a large volume. 

This increases pressure of course.

Your exit air mounted radiator will work grandly IF you can get the whole thing sealed, and not otherwise- the high pressure will go hand in hand with sealing challenges.

You'll have some gaps , so the minimum inlet size might need to be increased quite a bit.  In the photos , it look slike a substantial gap will be required around the exhaust pipe. 

 

the next problem you might face is the production of a low pressure region where you want it. This wont be flush with the skin, it will be up a recess/duct. ideally it will work as some thrust.

 

Next thing, parasitic drag is proportional to velocity CUBED . Put a 500cm2 flat plate in the wind at it will consume 10HP at 120 ks !!!

Unfortunately, you are going to have to get air from somewhere to run your radiator, which means having SOME frontal area.

 

 

glen

 

 

I thought drag was proportional to velocity squared. And power required was proportional to velocity cubed. And the difference was because you need more power to go faster for a given amount of drag. P.S. I am amazed by how much you and others on here know. 

I remember reading about someone who flew through a valley and then saw later that there was a power line strung across it. I have been tempted to fly low over hills avoiding headwinds - not clever of me. 

3 hours ago, aro said:

Of course you can. It's part of BAK.

 

Rate of descent = power required / mass.

 

Power required = drag * TAS.

 

Drag = parasite drag + induced drag.

 

Parasite drag is proportional to airspeed squared.

 

Induced drag is more complicated, but it is inversely proportional to the square of the airspeed.

 

Airspeed, airspeed, airspeed. It's always airspeed. Headwind or tailwind, the airspeed doesn't change, so the power required doesn't change and the rate of descent doesn't change.

I notice that OME did not acknowledge this answer. The first time I remember OME posting a question on the forum, he was trying to say that if an aircraft was trimmed in cruise and lost some power, it would slow down. I pointed out that if a trimmed aircraft loses some power, it will descend rather than slow down. Crickets. To be fair, he did acknowledge someone was right when he said that the lift equation was based on true airspeed rather than IAS and he was corrected.

I didn't even think of those equations. I just thought that the issue fell outside the equations because the aircraft moved with the air mass.  

13 hours ago, old man emu said:

No, I didn't. I asked the question to stimulate thinking. Is it my idea to increase my own knowledge? Partially. Is it my idea to have student pilots think about some aspect of flight - yes. Did my twisted mind come up with this method? NO!!!!

 

Way back in the centuries BC (that's Before Computers) the Greek philosophers and teachers came up with the Socratic Method. The Socratic method is a teaching tactic in which questions are asked continually until either the student gives a wrong answer or reasoning or the teacher is satisfied with the student’s responses. Teachers usually employ this tactic to develop critical-thinking skills in students, to improve their intellectual thinking about the subject.

 

If this method is anathema to people, then I can only form the opinion that it there is no longer time in this Life to sit under a tree and ponder the Why of our activities to gain a better understanding of the How. 

OME, you are not in a position to teach other people in the forum because the people who you try and teach understand your questions better than you do. 

OME, you are not using Socratic questioning. You asked one question a the start, and then were mostly making wrong statements. Socratic questioning involves leading students, step by step, question by question until they learn something they already knew, as it were. 

I can just imagine Socrates asking his students questions where he's not as smart as them, and becoming more and more frustrated when they don't answer the questions the way he wants them to, and telling them how upset they make him. 

I just saw OME write "gone" on the forum. Maybe he's going to disappear for another 12 months. While he's away, maybe he'll work out that the mass of one litre of water is not 100 g.  

So, then Socrates would storm off out of the forum. 

This is an aviation forum, so people are obliged to callout incorrect ideas. I never managed to convince you that the mass of one litre of water was not 100 grams so here I was not going to go beyond merely pointing out to you that you are wrong. 

Okay, I’ll give the mass thing one more shot. The F in the formula F=ma is measured in newtons, not kg. That is how come, when it comes to gravity, it is 10 times bigger than mass. IIRC, you posted a picture of a spring scale. On one side the scale showed the force in newtons and on the other side the scale showed the force in kg. 

Some things do indeed never change, like you posing questions to teach people things and then getting upset when people don’t answer the way you want. Sometimes I wonder if your posts are an elaborate joke, but then I remember that you have gotten me booted off the forum for disagreeing with you. 

4 minutes ago, old man emu said:

That's what I like about the people on this forum. - NOT.

If you ask a question for the sake of better knowledge, you immediately get attacked for being a fool. Nobody ever tackles the question to provide an answer, or else they take the proposition to extremes.

 

You didn’t ask the question to improve your own knowlege…

Y all have to admit that the idea of gliding into the wind to maximise your glide distance is worth some LOL’s. 👍😆👍

7 hours ago, old man emu said:

When I posed the question, I was thinking that most often you want to maximize the distance you can glide. That means getting your airspeed to the aircraft's best glide speed. If you have no thrust from the engine to move the aerofoil though the air to generate lift, why not turn into wind and let the moving air add a bit to the air movement resulting from the horizontal vector of your downward motion?

 

Turning into wind won't keep you aloft any longer? I know that it was only with RC gliders, but I could keep one of them stationary if I faced it into wind. 

 

 

 

You most often want to glide to the best place to land. BUT if you want to maximise the distance you can glide, you will turn so you have a tail wind… and you will stay aloft for the same amount of time. 😆 

Bit off topic. I find submitting a sartime with the naips app quicker than submitting a flight plan with ozrunways even if I have already done the flightplan with ozrunways for fuel and etc. Im a noob. To not answer your question, Id use both for a time and see. I assume you have adsb on the garmin? Nice profile plane, btw.  

The only things you will ever need are 10 L water per person and 2 EPIRB’s and warm clothes. Other survival gadgets are just toys IMHO. 

Just now, Thruster88 said:

Well Thrusters in Australia did become orphaned when the factory became dysfunctional and died.  

☹️