Bruce Robbins

Quote: "My issue wasn't that the Va is lower than Vc or Vno - this I would expect. But it was how much lower it is for the J170 than for the J160. Sort of implies greater structural strength for the J160 than the J170?" Hi BlackRod, Va is not a function purely of airframe strength. It is a combination of structural strength and stall speed. The link provided in post #7 explains how it's calculated. The J170 has essentially the same strength as a J160, but because the stall speed is lower, then the Va must be lower. If you look at the specs for many of the European hotrods, you'll find high cruise speeds but low turbulence and manoeuvering speeds, because they have to meet a lower stall speed requirement. A lot of GA aircraft actually quote different turbulence speeds based on how much weight you are carrying. The lighter you are, the slower you have to fly in turbulence. Cheers, Bruce

Zodiac3813, Cooling (Cylinder Heads and Oil) can be problematic with any air cooled engines. There is voluminous info available on the subject if you search online, but I suggest you speak to knowledgeable L2s or LAMEs before doing too much changing. You will often find that fixing one thing will unfix another. It can be a frustrating business. Having said that, in my opinion 100 degrees C is too hot for continous operation with a jab motor. We like to keep our school aircraft down below 80-90. You'll also find the temp going over 100 once you get a bit warmer than the 26C OAT you've quoted. We have found that sealing the gaps around the oil cooler is sometimes counter-productive, and you may get better results by directing some cool air flow over the sump as well. You should not need to add extra oil coolers. Cheers, Bruce

Hi Guys, I haven't seen the news reports, but spoke to an Oaks airport local. It was a landing gone wrong, resulting in damaged aircraft on the runway. The news footage was taken after the removable wing was removed for stowage. As Dave has said, pilot is OK. Cheers, Bruce

"Arrived in circuit at YWOL to hear "Welcome to Wollongong Ross" over the radio. Those AFRUs get smarter all the time." G'day Ross, Mea culpa for the AFRU re-programming. Heard you come in while I was busy circuit bashing with a student in one of our J160's. Saw the HARs guys crawling all over the Cheetah too as we drifted past on upwind. Looked like your own personal crew of "Erks" re-arming the spotted cat for another sortie. Cheers, Bruce

You may be in the twilight zone Flying_Doggie :) , but the windfarm isn't. Just near Gunning. Google Earth will show it. Bruce

Hi Ian, No, scheduled scans are only available in the paid version. I don't usually use scheduled scans, because I work on the basis that once a system has been cleaned, or checked as clean (which the boot time scan will do) then there should be no need for further scanning provided the antivirus software is always running. If the software has been switched off for some reason, and a virus did get installed, then it will get picked up once the anti virus software is re-started, because the av software is checking all memory resident programs. For business users I'm now using Norton av products. Norton was rubbish a few years ago, but has improved greatly since then. Cheers, Bruce

Hi Qwerty, I'ved used both AVG and Avast for many years. Installed both on many customers systems as well. I personally prefer Avast for its speed and ability to clean difficult to eradicate viruses by doing a special scan at boot time, and BEFORE Windows starts loading. Some people don't want to have to register with an email address, therefore don't want to use Avast. Both are pretty good products for the price. :) The green USB cable your mate has is a special cable made for the job. It may need some software installed before the PC's can communicate, but that should come with it. I recommended the external drive because it is simple, can be done in stages if required, and most of all, provides you with a backup solution to use after the changeover. I've seen too many upset people who've just realised how much they've lost after a disk crash, or in the case of a laptop having the whole thing stolen. Happiest laptop story: (Warning - long and probably boring) Brother-in-law rocks up one day with a rather sad looking laptop. "Found this beside the road near home. Police not interested. Think it's fixable?" "Dunno, let's have a look" Once I'd worked out the laptop had been dropped from a fair height, then run over, suffered a cracked the LCD, cracked motherboard, shorted internal power regulator etc etc, gave the verdict. "Nup, its stuffed" So, removed the disc drive and connected up to a little converter gadget. Plugged it into another PC and rescued a whole lot of documents and about 500 photos of somebody's overseas holiday before it too died. No joy looking through the photos, but one of the documents yielded enough clues to possibly identify the owner of a local business. Couple of discrete enquiries later and one very happy camper re-united with a couple of CDs full of his only copy of all the photos taken on a once in a lifetime trip back to the old country to see a new grandchild. Had borrowed his wife's laptop, put it down on the roof of the car while he got out his car keys with a mobile stuck to one ear, then driven off.

Hi Mike, I've only got a few hundred hours in various 172 sized GA (General Aviation) aircraft, but many hundreds in the various Jabiru models. All the Jabirus have shorter travel on the rudder pedals than most GA aircraft and a nosewheel that is closer to the mainwheels. The pedals are also physically shorter, so combine the short pedals, shorter pedal travel for a given nosewheel movement, and closer coupling of mains to nosewheel and you end up with much more sensitive steering on the ground. The shorter pedals and throws also give a "stiffer" pedal feel. (particularly on the larger models like the J200/400). I think that once you re-program your feet to a new tactile feedback loop, you will find the J400 easy to handle on takeoff. Remember to think rudder pedal pressure, not rudder pedal movement. Having said that, I would use some different takeoff techniques. The Jabs are much more sensitive and responsive to nosewheel steering on the ground, and most people get into trouble because they overcontrol and end up in a PIO. By using full forward trim you're loading up the nosewheel even more, and delaying the changeover from nosewheel to rudder steering. So: Method 1) Set the trim Neutral. Lift the nose wheel just off the ground once it is happy to do so, and then let the aircraft fly it self off in that attitude (which should be pretty much your initial climb attitude). The speed to lift the nosewheel will vary depending on the aircraft weight and CG. I have only flown J230s in the J200/400/230/430 series, so cannot comment specifically on the J400, but in some of the 230s I've flown with full fuel and only a light pilot, the nosewheel almost jumps off the ground by 30 kts and can require some forward stick. The response to rudder inputs is "softer" with the nosewheel in the air and avoids that darting from side to side you get if you're overcontrolling slightly. Method 2) Set trim neutral, leave the stick neutral and let the nose wheel stay on the ground till you get to 50-55 kts or so (depends again on the weight). Rotate positively and the aircraft should lift straight off. During the ground roll be sensitive with the rudder pedals, and keep thinking pressure, not movement. If you develop a bit of a side to side swerve, put pressure on BOTH pedals till it stops, then gentle corrections again to regain your desired track. Regards, Bruce btw: There are a few guys on this forum who fly the J400s, so you should get some more model specific advise soon.

Hi Qwerty, By the sound of it, you're a normal human, not a computer geek, so I'd suggest the following. 1) Get a large capacity USB Flash Drive (also known as Thumb Drives or Memory Sticks). Capacity depends on how much data you need to move. 4GB will be about $20, 16 GB about $55. Plug the Flash Drive into a spare USB port and simply Drag and Drop all the files you want off the old computer onto the Flash Drive. Reverse the operation on the new laptop. Alternatively, buy an external USB Disk Drive ($100 will get about 250GB). Use this to do the data transfer, then keep it and USE it for doing your backups. Specially all those irreplaceable photos. 2) Don't even think about doing this unless you have lots of time, patience and a friendly IT expert to call in. You'll need to have a kosher copy of XP on a bootable CD, and ALL the relevant drivers for your new laptop, otherwise half the features like sound, screen resolution, inbuilt modems, and CD/DVD burning won't work properly. 3) AVG Free and Avast Home (free) are both good. I have found Avast a bit better at handling viruses, and less of a drain on system performance than AVG. Avast has to be registered with an email address every twelve months while AVG doesn't. Download FREE antivirus software - avast! Home Edition Regards, Bruce (25 years in IT)

Peter, hard to tell from the photo, but the fibreglass sheathing on the prop seems to be starting to de-laminate. I'd get it looked at asap by someone who knows wooden props. If it is de-laminating or coming away from the timber, it can get worse very quickly in the air, and I guarantee it will get your attention. Cheers, Bruce

Under the new Drug and Alcohol testing regime already quoted, the permissable level of alcohol in the blood is .002%. Under the regulations, "8 hours bottle to throttle" CAR 1988 (Civil Aviation Regulations) (3)A person shall not act as, or perform any duties or functions preparatory to acting as, a member of the operating crew of an aircraft if the person has, during the period of 8 hours immediately preceding the departure of the aircraft consumed any alcoholic liquor. Penalty: 50 penalty units. So the exam is correct. Both .002% and 8 hours apply.

Carby ice forms when the air tempfalls low enough to freeze the water vapour in the air. First you need the water. Dry air - no ice, humid air - potential ice. The temp drop occurs because there is a pressure drop as the air passes through the carby. The pressure drops because the air speeds up going through the restriction in the carby. The smaller the throttle opening the greater the restriction, the faster the air flow, thus the greater temp drop. Carbies are thus more susceptible at low throttle openings. Sometimes the icing occurs while the throttle is low, but doesn't become apparent till you have re-applied power and started climbing away. The ice in the throttle then starts warming up and breaking off. The resultant rough running or misfire sure gets your attention!

The Victorian Bushfire Appeal 2009 [imgalign=right]http://www.theaviatorlounge.com.au/images/bushfire/bushfire01.jpg[/imgalign]On Friday 27th February, 2009, The Illawarra Flyers are using their weekly Friday afternoon BBQ to raise funds for the Australian Red Cross Victorian Bushfire Appeal. Dick Smith has been invited to attend (and will arrive in style in his Augusta helicopter) to give his views on the future for sport and general aviation in Australia. During the evening we will be conducting an auction of items donated by local businesses and individuals. The items range from bottles of wine to joy flights in the Historical Aircraft Restoration Society's Lockheed Constellation, dinner vouchers to aviation memorabillia. Any-one wishing to support the auction and unable to attend, can place a bid at any time with our auctioneer for the night, Ray Peterson, either by phone on 0417 211 092 or by an email to [email protected]. Ray is already accepting bids. There is complete truth in the rumour that Ray is totally corruptible and will accept the highest bid on any item to ensure that you secure the one you want! We urge you to have a look at the magnificent list of donated items at www.theaviatorlounge.com.au/bushfire/index.html The Illawarra Flyers are a group of aircraft owners, pilots, aviation enthusiasts, businesses and employees based at the Illawarra Regional Airport. We are charging ourselves $20 per head to attend the night and ALL proceeds go straight to the Red Cross. Thanks, Bruce ps: Sorry for the saturation cover, but we figure it's a good cause.

Pudestcon, It's the Airborne Aviation spreadsheet. See the details in post #5 above.

Hi John, I've used this spreadsheet for several years. It's great. Simple and quick. When I first got it I used a password cracker to look at the formulae with a view to making a few "tweaks". Took one look and closed the bonnet again very quickly. They are extremely complex. You will find that if you simply enter the data where specified the sheet works out a perfect flight plan for you. In the middle of the sheet are two boxes for fuel. Enter the amount of fuel you have into those boxes (marked Left and Right tanks) and the endurance will be calculated based on the fuel burn you entered into the Aircraft Reference Card. If you only have one tank, just use one side. Regards, Bruce

Captain Geoff, This is the latest info I have. Regards, Bruce Robbins (Illawarra Recreational Flight Centre) =========================== Additional operational information regarding Wings Over Illawarra Sunday 22FEB09 at YWOL This information will be published in a NOTAM closer to the day, but is being distributed now to help with planning arrival times for anyone out of the area planning to fly in. Main items to be aware of is that runway 08/26 is closed all day. Western end of 08/26 only available to light aircraft (in particular taildrag) in strong cross wind, with pilot's responsibility to maintain communications and maintain safe separation. Runway 16/34 operational with closure to GA/light aircraft 1000-1050, 1210-1245, and 1420-1500 local time. These closure times are to allow for Roulettes, r/c model aircraft and Skydive the Beach displays. All arrivals by 0930 where possible, but no later than 0945 to avoid first closure period. If arriving from further afield, please be aware of closure times and plan to avoid these. PLease distribute this information to others planning to fly in. Thanks for your consideration Phil Ayrton Secretary SAAA Chapter 4 =================================

If you gents are having trouble sleeping over all this scientific discussion, please download the 10mb file located at the bottom of this page. It contains very detailed and well written descriptions of what is happening to the aircraft during all phases of flight. http://flightlab.net/Flightlab.net/Download_Course_Notes.html There are some nice videos on the site also, showing some of the things discussed in the notes. I have found the notes explain very nicely many of the behaviours discussed above, including how and why an aircraft rolls into or out of a turn when stalling. As some-one famous once said "Things are not always as they seem". Happy bedtime reading, Bruce

Thumper, This site may be of interest. Potomac Books - Amelia: A Life of the Aviation Legend Bruce

Here's one from New Zealand. Touchdown on the first section which slopes uphill, then hang a right hand turn at the bald patch soon after, and finish the rollout slightly downhill.[ATTACH]6806.vB[/ATTACH]

Last time I took some friends for a local sightseeing trip in a rented Cessna 182, I got a severe fright after 45 minutes or so. Checked the fuel guages for the first time since take-off, after having been questioned/pestered non stop about the fabulous sights passing by below. .............Whoah, whats happened to all the fuel out of the left tank!! Needle seems to be bouncing on empty!! ........Quick change from "Both" to "Right", listen very intently to the engine noise for the next five minutes, and then enjoy the afterglow of adrenaline induced thump, thump, thump noises in the chest cavity slowly subsiding. For a bit of light reading on drawing fuel from high wing wing tanks (no I'm not stuttering) try this ........ http://www.moonflight.org/Documents/Fflow.pdf Cheers, Bruce

Yep, It's caled a Furio. http://www.falcomposite.com/ Seriously though Disperse, it's not as simple as just substituting carbon fibre rovings and or cloth for timber. The two materials have completely different characterisics.

Tony, Interesting point, and one I've not thought much about. If what you've experienced is widespread behaviour in reflex flap designs then you've made a number of very valid points to incorporate into operating such aircraft. Do you know if there are any aerodynamic "fixes" like stall strips, boundary layer trips, wing fences, vortex generators etc etc that may introduce some feel back into the stall? Bruce

Mathew, They both do the job. The one's without a slide (Jepessen CR series) are much easier to take with you in the cockpit. If you're young and still blessed with good eyesight, then the CR2 fits nicely in your shirt pocket. If not, then the CR3 is bigger and easier to read. I agree with the others. Don't waste any money on the electronic ones (and yes, I did!). My CR3 goes on every nav flight. The $150 ASA electronic paperweight is still in its 6 year old box. Bruce

Hi Ian, Like I said, I'm being a little pedantic here so don't take me too seriously. In teaching someone to fly, the actual detailed mechanics of a stall are not so important as learning to recognise when you are getting close to a stall, what might happen if you do, and how to avoid being bitten. Unfortunately people are still killing themselves by stalling in from low altitude, and it should be totally avoidable. Anyway, back to pedantry. I agree that Reynolds number, planform, slots, slats etc etc are usually out of our control in the aircraft we typically fly, which is why I said before "they are not usually relevant". The one that is however is camber change, and so flaps (and power settings) can change the stall behaviour significantly. As an example, go for a fly in one of the LSA55 Jabs and try some stalls. No flap simple stall - benign as anything, basically not really stallable. Full flap simple stall - bit more interesting. Full flap simple stall with 2400 rpm - sudden, sharp wing drop, large nose down pitch. Do that one turning final and you won't survive. As I intimated before, the average student probably doesn't really need to know why and how the plane reacts differently, just that it does. Have a look at this diagram which shows Cl plotted against AoA and you can see what I mean by the stalling angle (of the same airfoil section) decreasing with flap. [ATTACH]5935.vB[/ATTACH] Note how the peak Cl (stalling angle) is shifting left and up. Regards, Bruce