jcamp

Dont know if it will glide very far?

One way of looking at it is

320 mph=469 fps

180hp, 90% prop efficiency @ 469fps drag=190lb=86kg wt

C1b is 500 to 1,000 kg so ~ 6:1 at 320mph (278 kts) if only 500kg more if heavier

@ say 120 mph square relation gives 12 kg say 20 to allow for increased a of a and induced drag, so more than 25:1

She at one stage dismisses one of two Professional metal fatigue specialist because she feels one is more credible than the other.Mike

For those who haven't seen them the points on an S/N graph look more like a shotgun pattern than the nice lines in fig xxx in a textbook.

IIRC Key point with dimples/not dimples relates to Reynolds Number (RN - roughly =10,000*size in feet*knots) a golf ball is in the 10,000 range and drag is due to viscousity hence dimples help. On a cannon ball they wouldn't.

Model a/c at 100,000, gliders at 500,000 GA at 1,000,000+ and airliners at 10,000,000 (obviously with variations due to what and where in the envelope they are) tend to have considerable variations in Cl and Cd curves even if they have the same airfoils. Hence different airfoils are used. A quick example on the 23012 (eg DC3) airfoil is at:

http://naca.larc.nasa.gov/search.jsp?R=998183&id=7&qs=Ntt%3D23012%26Ntk%3Dall%26Ntx%3Dmode%2520matchall%26N%3D0%26Ns%3DHarvestDate%257c1

There is a noticable difference between 8,000,000 and 3,600,000 and would probably be pretty bad (unsuitable) on a model at say 360,000.

This was a big problem in the early days (pre mid 30's) as it wasn't really appreciated and was one of the reasons early wind tunnels tended to give misleading results. Classic example was the supposed theorectical inability of the bumblebee to fly, they didn't allow for the low RN and so got the wrong answer (the scientists not the bumblebee)

I doubt that a/c registered at 544/600/whatever will suddenly be OK for 700/760 regardless. Maybe 19- with some paperwork which would be pretty carefully looked at but doubtful.

New build 19- could be done with appropriate stall speed, eg J250.

For new 24- LSA factory certification to ASTM is only to 600. This leaves VLA for 2 seat or FAR23. Fair investment for a gamble in todays economy.

I wonder why: "If high humidity does exist, it would be wise to add 10% to your computed takeoff distance and anticipate a reduced climb rate."...

Humidity is (crudely) when 18 gm of H2O replaces 29gm of N2+O2 in a certain volume, all this gets a bit complex but what counts is absolute humidity which is a function of relative humidity (what BOM report)and temperature (the temp bits comes from higher temp=higher vapour pressure of H2O, roughly doubles every 10C reaching 1013mb @ 100C)

For airframe

Higher absolute humidly=lower density of air=less lift

For engine

Higher absolute humidly=lower charge mass+less O2=less power

Only distantly related: Is there such a thing as a generic chart that shows the impact on a/c performance, or more simply, air density, of different (airfield) elevations and ambient tempuratures? .

NAPPF Density Altitude

at result 1 of 408

Unable to comment on 170 but the 160 has far more aerodynamic control on landing than the LSA etc. Bigger ailerons, rudder etc gives far more control and avoids that round out and become a passenger feeling.

Regarding 8 and other odd voltages in cars. A common stetup in a 12V vehicle was to have a dropping resistor so the ignition normally worked on 8V, there was also a direct feed from the starting switch/circuit so that on starting the ignition had 12V (actually 10 or 11 depending on how sick the battery was) for easier starting.

Without exact knowledge of the a/c etc

Deflection of split flaps increases the camber and hence the lift. The top surface bit is important to a point as in 'what over simplified half truth do you believe in'. On takeoff at low deflection the (bigger) increase in lift presumably outweighs the (smaller) increase in drag.

Do it by the flight manual.

Motza - Its not about instructors YET.

The chain goes:

Academics producing theory and publishing it (promotion)

Consultants teaching it (often the academics)

Empire starts in public service (CASA in this case)

Gullible people believe it and help propagate it

Hey Presto! a new industry

As previously mentioned the whole business is pretty complicated see any uni level aerodynamics text for an introduction. One way of looking at it without too much mathematical fluid dynamics is consider two separate (but connected) factors.

Lift generation - downwash off the trailing edge of the wing due to wing section including camber, angle of attack, coanda effect etc gives a momentum change which requires a force. Crudely density, span and velocity (rho*span*V) give the mass moved per unit time with chord,lift coefficent and velocity (chord*Cl*V) give the downward velocity; multiplied together we have a momentum change (rho*span*chord*Cl*(V^2))=(rho*A*Cl*(V^2)). The 1/2 in the book formula comes from early drag theory so to make the formula look the same as the drag formula double Cl and divide the whole thing by two.

Adding. This is of course for subsonic a/c. The individual molecules are moving at (loosely) the speed of sound in all directions for short distances (less than 0.1 micron) in a random manner before bouncing off another molecule and going in a different direction. As the arithmetic gets too difficult we have to consider it as a fluid which is nasty enough even though with numerical methods we may look at 1,000,000,000,000,000,000,000 molecules together..

Transfer the force to the wing - This is where Bernouli comes in. The downwash accelerates the air on the top of the wing and most (not all) of the force transferred to the wing comes from the Bernouli effect there.

PERSONALY i thought it was crap!!!!

Expect more of it and not only in Aviation

Depends who issued it. If CASA then it is an ID issued by a Fed Govt Dept and counts as X points. If RAA, whatever airport etc then no go.

Maybe the title of the thread has it confused.

I think it would be awkward in a J170. certainly was in a C150 without the center stick. She didn't appreciate the offer of a T shirt though!

Correction to add -you need to improve your spelling it's proposition.

The 45min applies to any flight including a single circuit. You don't need to have the wind forecast wrong by much to be off by 15min in a 4hr flight.

Ignoring this stuff is one reason why fuel exhaustion features prominently in the stats.

Regarding advertisments it pays to examine them closely.

Fuel 90 litres = 63kg @ 18 litres per hour gives 4.5 hours + reserve,

Doing it easy @ 115kts x 4.5 hours = over 500nm

Seems a bit light CAAP234-1 says 45 min fixed reserve and recommends 10% variable (I prefer 15%). It is no longer in the regs in stone but CAR 234 does say a court shall consider CASA recommendations on fuel.

My thinking for 5hrs total is 221 min + 15% + 45min

221 min gives 434nm.

I'm hoping there's room between the top of the dash and the windshield to mount it in the center and angle it towards me.

Also, it may have been an isolated case but one time when I was coming into Shepparton I switched over at about 15-18 mile out and heard nothing but as I got closer I started picking up some weak calls that became stronger as I got closer. I never asked but it may have been possible that if they were weak as I got closer, would they have heard my call especially if anything happened like colliding with an aircraft that was on area not local that had just left Shepparton - just another thought.

The exact effect depends on frequency they are using, where they are aiming, receiver design, antenna setup (inc bank and pitch), quirks in the transmitter, phase of Jupiters moons etc etc etc.

Short answer is radio comms at Shep for traffic should be regarded as even less reliable that elsewhere.

With fuel cards you really need three - Shell, BP and Mobil. Not sure on what the rules are but I think they are supposed to be tied to an a/c; something to do with restrictions on leaded fuel. Best bet is a crowd that give you all three with one account.

A discount setup would be even better.

Released today

Here:

Discussion Paper DP 0802OS - Mass Increase for Aeroplanes Administered by RAAO

Couple of things in a J160

Had a bit of trouble on a nrm-bud leg. Just had the new jets fitted and got nervous about the fuel gauge readings so went into cca to dip the tanks ~25l remaining so mutter grumble about the new jets. After some tests at bundy turned out to be an intermittent leak from header tank drain valve.

On another trip I had an engine failure due lack of fuel and restarted with highly unbalanced flight. Landed ~ 5 min later and taxied in. Subsequent draining on a level surface got 18L from the line to the engine. Action was fitting a level indicator in the header tank to show any departure from a full condition.

It's not unheard of for CASA to pull a type cert. Didn't the Vickers Viking suffer this fate for it's tenenct to lose a wing in flight or something along those lines back in CAA days?

Personally I'm scared, not of flying but of xylene, benzene, hexane,etc...[/Quote]

Better take up gliding to avoid petrol.

For 95.10

http://www.casa.gov.au/rules/orders/095.htm

and select

95.10 Privately Built Single Place Ultralight Aeroplanes – Exemption from Provisions of the Civil Aviation Regulations

Which seems to cover it. Other stuff is in

95.55 Certain ultralight aeroplanes-Exemption from provisions of the Civil Aviation Regulations 1988

and this does have engine resrictions for some types but not 95.10