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For goodness sake, use the book! As for applying flap during the takeoff roll, you are asking for trouble. One day you will either forget because you are dealing with some other problem, or something will occur just as you reach down for the switch or the bar. I've already nearly been killed by a sticky Cessna flap switch and I don't take my eyes off the runway just to check if the flaps are extending. Things can happen very fast and you don't need to add unnecessarily to your own workload pulling this trick. The gravel strips I've used require all your attention just to keep the aircraft pointing in the right direction and on "centreline" Neck-winding-in mechanism obviously an optional extra for you? Stik |
TSB Accident Report
http://www.tsb.gc.ca/en/reports/air/...0/a98o0190.asp Aviation Occurrence Report Stall/Collision with Trees on Take-off Piper PA 28-151 C-GDVL Espanola West, Ontario 27 July 1998 Report Number A98O0190 Summary The pilot and three passengers were departing in the Piper PA 28, serial No. 28-7615332, on a visual flight rules (VFR) flight from Espanola West to Ottawa, Ontario. The runway surface was grass on uneven, sandy soil, made soft from recent rain. The pilot made two excursions down the runway before the aircraft became airborne on the third excursion. After the aircraft got airborne, it struck trees to the left of the departure path and crashed into a wooded area. An intense, post-crash, fuel-fed fire immediately broke out which consumed the cabin of the aircraft. One passenger, an infant, perished in the aircraft fire. The pilot and the other two passengers escaped the burning aircraft and were found about 40 feet from the wreckage by ambulance and fire-fighting personnel. They were transported to hospital where they died later from burns. The one good thing about sand was that you needed less than 100 yards to abort -- without braking. |
People seem to be mixing up short field and soft field. These require two different techniques.
Soft field, you pop the a/c up into ground affect to accelerate, whereas with a short field you use standard techniques for take off, except you are rotating at a lower speed than normal and using a higher flap setting (generally...). Plus if needs be when lining up on the strip, if you need to, then shut down and push the machine back into the hedge as far as it'll go before commencing you take off run. With a soft field, one of the major issues is don't stop or you'll sink! If you are half way competent, there is no problems with putting flap down just before rotation. That is a normal thing, especially if you operate from rocky or very short strips where you need every ounce of acceleration. Pulling a couple of great big flaps through the air is never going to help your rate of acceleration! |
Be my guest sticknruda, I learned a lot from creasing a Cessna:
(1) Not all instructors know everything. (2) Read the %^&*ing book and follow its instructions. Pulling the flaps out during rotation is asking for trouble. For a start on a Piper, you need to reach down to the floor. On a Cessna you need to either place a switch in a particular setting (you cannot rely on those little plastic ridges) or hold a switch down while watching an indicator. Quite a lot of C172's don't even use flap on short field anyway. All you need is for some other problem to appear while you are performing this act and you are stuffed. But go right ahead and develop your own technique. Its not as if anyone took any care writing the manual, you obviously know better. |
Originally Posted by wombat13
Ronnie, one of the problems with asking a question on the forum, particularly a question of such importance as short field take off technique, is that you will inevitably get contradictory answers and as has happened in this case, things do go off at a tangent.
I watched the spat sunfish / QDM and this made me rethink what I told you. In the case of my advice, deploying flap just before rotating into the ground effect is, perhaps, best left until you have a bit more experience. Deploy prior to the roll. The Wombat Understand the correct technique for your aircraft. Read up on STOL (both short and soft) for your aircraft. Find a FI who can instruct. Try deploying flap both before and during the roll - settle with what you are comfortable with. The difference will be only a few fields you won't be able to use. Don't be afraid to ask the FI to "test" the speed tolerence of your aircraft. The POH is vital as a "get out of jail card", but for sucessful STOL, experimenting with an FI beside you could save your life later. It takes some balls to come on the forum and admit bending an aircraft. The sh1t that is being poured on Sunfish by one or two people for doing this is representative of appalling ignorance and does not help. A wise man learns from his mistakes. A very wise man learns from other mens mistakes. Let's keep the forum as a place where we all can continue to share and learn. The Wombat |
Pulling the flaps out during rotation is asking for trouble An examiner once showed me a SF landing in a 2000 172SP. We touched the runway right at the end, and were stopped in about 100m. He came in at 50kts, and just flew it into the ground and stood on the breaks. Never knew a 172 could do that...... |
An examiner once showed me a SF landing in a 2000 172SP. We touched the runway right at the end, and were stopped in about 100m. He came in at 50kts, and just flew it into the ground and stood on the breaks. Never knew a 172 could do that...... My personal best was getting the stall warner just going off on short final, touching down on the displaced threshold and stopping before the PAPIs. SD |
Sunfish, I often point out the GPS ground speed to students when they are on final approach. Why? Because in high wind conditions for example a 30kt headwind on approach will result in a much steeper angle of descent if descending at a normal rate.
My point being is that if a student does not 'think wind' they can easily end up very low on approach. |
The pilot made two excursions down the runway before the aircraft became airborne on the third excursion. On the flaps issue, using flap in various ways and indeed putting it on during the take-off roll are standard techniques in a variety of aircraft. There is no controversy. People seem to get rather stressy that a novice may read advice on this forum, go away and try it and end up in the trees. Indeed they may, but more fool them. If you get your licence and you still don't realise that flying is waiting to bite you then you deserve all you get. On the other hand, we all need to learn ways of expanding our personal flight envelopes and I have certainly learnt a very great deal from this forum and others, especially www.supercub.org. Today on the radio an MP was introducing a bill to limit (yes, by law!) domestic hot water temp to 48 degrees so that babies don't get scalded. Many of us fly because it gives a feeling of release and freedom from this kind of BS we have to put up with in society today. Don't let's infuse flying with the same neurotic over-protection. Yrs, SafetyQDM |
I'm sorry, but this seems to be a distraction. The groundspeed is an irrelevance in keeping the aircraft in the air and not stalling.
Certainly on short finals, it is the 'picture' and how it changes that has to be monitored. On finals you have to monitor the picture and the airspeed. To switch to read the digital output on a GPS would seem to be dangerous. I was always taught that once at base, don't look into the cockpit except for quick checks on airspeed. There are lots of other signals to indicate wind direction, drift and ground-speed - such as smoke from chimneys when approaching the destination - which would help in planning your arrival Add to that a decent circuit and, if necessary a go-around, I see no need to even switch the GPS on. Having flown at Camphill and Nympsfield you are taught to recognise what will happen in a strong wind, and adjust your circuit accordingly. I can't believe anyone teaches the use of GPS groundspeed. Wasn't it quoted as a possible cause of the crash at Blackbushe? |
robin,
In heavy winds you're right, but in light winds, with no windsock, into a very short strip GPS groundspeed is very useful. It is. One of the fields I take the cub into is 240m with an 8-10 foot hedgebank at either end. In that context, 5mph of wind is significant, especially if it is on your tail. Judging a light breeze like that is not easy, at least I don't find it so and certainly round here local wind direction is very variable. Many factors dictate whether an approach will end up in a good landing and wind direction and speed are critical. The more marginal the situation, the more critical is the wind and the more useful becomes GPS groundspeed. By choice, I wouldn't do without it. This all relates to low land flat field ops. If you are in the mountains, then the wind issues are different and runway slope will dictate approach speed and ultimate stopping distance. QDM P.S. Real Supercub pilots would think me a girl's blouse for saying that 240m is short! |
QDM
I hear what you say, but as a glider pilot I have never even thought of using the GPS for this purpose. I'm not sure it is even capable of resolving ground speed to that accuracy (well my one isn't) And with my eyesight, looking down into the dark cockpit to resolve a small digital readout and then looking back up into the brightness just seems bad news to me. I've gone into some short fields, but to me a properly setup and managed approach is what counts, not the numbers I have flown a Cub into short fields on occasion, but, as I say, it is the view that counts, and with a powered jobby you can always go around, or do a low pass first if you aren't sure. However, I will bow to your better judgement and experience |
With the greatest of respect, I wish to point out the logical fallacies going on here and my slavish devotion to "the book".
Some have suggested that "the book" includes procedures that are capable of being followed by pilots of low skill levels and that superior beings are free to practice other procedures which produce superior results. In one case, someone even posted that they could get much better performance from their aircraft than the performance charts indicated by using different procedures from those specified! This is deceptive. As my arrow manual says :"(the performance detailed herein)...can be duplicated by following the stated procedures in a properly maintained aeroplane". In other words they are repeatable, if you adhere to them, they work every time. I mean it quite literally when I quote an instructor who wrote;" If you don't follow the book you are literally your own test pilot." In other words, they are repeatable. To put it yet another way, the flight envelope (remember that lift/drag/ attitude thing?) has been established in conjunction with the procedures in the book. Use any other procedure near the edge of the envelope and you risk disaster. It was this unknown territory that claimed an acquiantance of mine, a highly experienced former leader of the fleet air arm (Australian Navy) who was helping a mate test fly his experimental turbine powered Lancair. They were testing its stalling behaviour and on the third stall they entered what appears to have been an unrecoverable spin. The tone of one or two posts here seems to suggest an even lower level of experience than I've got, or a flippant attitude to safety, which bugs me enough to reply in the first place. I try and do at least one short gravel strip a month to keep my hand in. These strips are about fifteen feet wide with a high crown and one of them has rising terrain, trees and powerlines quite close to one end. They require great concentration, as well as instant reactions if things are not going to plan. These strips, and thousands like them, are definitely not places to be reaching for a Flap switch or Johansen bar at fifty knots. During your takeoff roll, your right hand should be holding in the throttle/prop/mixture and nowhere else. Your eyes should be on either on your airspeed or your abort point (rule of thumb - 70% speed at halfway), or the windsock. Here's a tip, next time you do a flight review, tell your examiner that you can get better performance from the aircraft than whats published in the book, and that you have some real great non-standard procedures to achieve them that you are going to demonstrate to him, and see what happens next. PS: QDM, "Today on the radio an MP was introducing a bill to limit (yes, by law!) domestic hot water temp to 48 degrees so that babies don't get scalded. Many of us fly because it gives a feeling of release and freedom from this kind of BS we have to put up with in society today. Don't let's infuse flying with the same neurotic over-protection." QDM, there is by law in, at least this State in Australia, a thing called a tempering valve, installed in all new homes, that limits maximum water temperature to around 48 degrees by mixing hot and cold. The valve costs about forty dollars. Its fitment was requested by pediatric burns surgeons, hardly purveyors of "neurotic over-protection" after considerable research into both the causes of pediatric burns and the cost/benefit of doing something about it. We were also the first State in the world to require seatbelts be fitted to cars. Good luck with your Cub, I'll continue to neurotically stay within the boundaries of the flight envelope and the specifed procedures. |
This is a non-argument. Sunfish is absolutely corrrect : his "by the book and nothing else" policy will (hopefully) ensure that he flies safely, and that if anything does go wrong, he won't get the book thrown at him. Good luck to him.
Then again ... two weeks ago at Cranfield my plane landed with absolutely no problems in a cross wind of exactly twice the "demonstrated maximum limit" specified in the POH. I've often heard people say that this limit is simply there to cover the manufacturer's backside, a philosophy born of the litigious '80s in the US. Which does tend to make you wonder ... after all, I've flown with a lot of very experienced guys who do things which defy the manual, and I'm still here. I'm not saying this is the way to go, I'm just stating facts. Looking at my X-wind example, and watching these guys do their "non-POH" things, has made me wonder how much of the POH actually reflects real aircraft limitations, and how much "don't sue me" margin is built in to many POH "limits" ... Let me say quite clearly that if you're a new or low-houred pilot, and you decide not to follow the POH to the letter, I think you're stupid. If you decide to try out a new "technique" simply because you've read about it on this forum, without actually flying with someone with the requisite experience first, you're equally stupid. But would I slate the guy who showed me how to really get my plane out of a short, very soft field recently, using techniques which don't appear anywhere in my POH ? Well, perhaps when I've got 12,000 hours as well ... :rolleyes: Fly safely, FF :ok: |
sunfish,
The official POH of my Super Cub contains precisely nothing whatsoever regarding flying techniques in different situations. Zilch. What do you suggest I do, therefore? Stay on the ground. And the idea that reaching for the flap lever on take-off is somehow dangerous is preposterous. You really have no idea and I am not sure why I am rising to this. I suggest the real barrier to safety is your blinkered attitude, not people using tried and tested techniques to get the maximum performance out of their aircraft.. QDM P.S. I am very glad I do not live in a place which limits hot water temperature by law. If vehicle speed was limited to 10mph there would be fewer road deaths and presumably orthopaedic surgeons would then be as happy as paediatric surgeons are in your state. |
Good luck to you QDM, lets hope you never expereince flap assymettry while using your "technique"
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This is a non-argument. Sunfish is absolutely corrrect : his "by the book and nothing else" policy will (hopefully) ensure that he flies safely, and that if anything does go wrong, he won't get the book thrown at him. Good luck to him. If we all had to fly by the book most of the aircraft at Old Warden would be grounded - and most are a lot nastier than your average spamcan. |
I suspect that "the book" for older aircraft is simply the techniques of the flying syllabus of the day. I suspect that the Cubs "book" probably not be much different from the book "Stick and Rudder" or the military ab initio training syllabus of the day. So its nonsense to say they should be grounded.
As for lowering flaps during takeoff roll, you are asking for trouble along the lines of what happened to the guys mentioned in the report referenced below. It describes resulting accidents as well when either the flaps choose that moment to fail to extend or have simply been forgetten because of workload. "Being suspicious of such claims in increased takeoff performance, I spoke with an Air Tractor representative who confirmed that not only was this takeoff procedure improper, but the theory behind making such a departure is untrue; the drag created by the wing flaps is negligible during this phase of operation, and will not decrease the takeoff distance by a measurable amount." http://www.agairupdate.com/aau/artic...apEnglish.html Flappy, I'm surprised that your manual contains a "demonstrated Maximum Crosswind limit". Mine simply states "Demonstrated Crosswind Component", and I was taught that this is indeed not a limit, but only what has been demonstrated. If your coordination is very good or you get a lucky gust, you can sometimes do better than whats been demonstrated, but again of course you are being your own test pilot. |
Sunfish, the last lines of your quoted text :-
Editor’s Note: The opinion of this author does not necessarily reflect the opinion of AgAir Update. It should be noted that lowering flaps before takeoff may be a safer practice, as per the preceding accident reports. However, it does not preclude that lowering flaps midway during a takeoff roll will reduce the takeoff distance. FF :ok: PS : Calling me "Flappy" - does this mean we're engaged ?:p |
Originally Posted by Sunfish
If your coordination is very good or you get a lucky gust, you can sometimes do better than whats been demonstrated, but again of course you are being your own test pilot.
I put an Archer down in Bussleton WA last month with a recorded x wind component of 28kts. There was no lucky gust and at 120 hours I don't consider my coordination to be very good. My difficulty up to this statement was what I felt was QDM's somewhat cavalier attitude and that yes, some idiot stude would take what he was saying and give it a go - irrespective of their experience. Your comment on x wind maximums and not exceeding them is simply too slavish. The Crown tasted pretty good that evening. The Wombat |
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