Larry F - OMG I can UPGRADE my wardrobe as soon as I can find the old Monkey Wards cattle log 
Variation on John's & Catdaddy's stories, have seen this happen countless times, am sure many of you gues have too. FLyer completes the pattern, typically around 5:30, has plenty of time before 8:00 is up. HOWEVER, around 6::30 he starts getting anxious and starts looping to shut off. Only the engine has another :30-60 seconds fuel left so it will not shut off - not the first time he loops, nor the 2nd, nor the 5th or the 10th loop he does. Meanwhile the effects are 1: the engine is now runing nice and lean an that 30 sec fuel supply is now good for a minute. More often than not the flyer has CAUSED the over-run. 2.: when the engine finally does shut off the flyer is now landing with about 20 twists in his lines, and in a glide. His .015 dual lines are now closer to an .030 monoline and he has no control and makes a lousy landing - or worse. WHile I have not seen Ted fly in a very long time I recall he used to do a couple outside triangles to unwind the lines from his pattern, I flat don't remember if he did any extras to prepare for his cut-off loops - but in either case he was obviously getting prepared. Oh yeah, he NEVER cut out in the outsides (at leasty not in public 
) because he KNEW where he was in his fuel supply and engine run. He would commence his cut-off sequence when he KNEW it was time.
The cut-off loop ONLY works when the engine is nearly ready to shut off anyway.
It has also been my expereince that IC engines ALWAYS cut-off in the same part of the circel in level flight too.
OK now the controversial part. Typically when the engine shuts off it can easily do it in some any part of the loop and NOT just dead center at the bottom. If the engine quits ANTWHERE but dead cnter bottom, why isn't the Landing score docked say 50%? I mean is a loop part of a smooth gradual descent to a gentle touch-down?
No need to answer, you know what I said is RIGHT, but it will never be scored that way, and frankly I wont lose any sleep over it...
Denny,
Shame on you!
I don't think you even read what I wrote about cut-off loops and their pros and cons. You may agree or disagree as to my reasoning but I think the thought that went into the points I made deserved more than a simple repeat of "showboating".
Your current post brought up a few things that can add to others' understanding of my point of view. Here are a few for your consideration.
Denny said: "WHile I have not seen Ted fly in a very long time I recall he used to do a couple outside triangles to unwind the lines from his pattern, I flat don't remember if he did any extras to prepare for his cut-off loops - but in either case he was obviously getting prepared. Oh yeah, he NEVER cut out in the outsides (at leasty not in public ) because he KNEW where he was in his fuel supply and engine run. He would commence his cut-off sequence when he KNEW it was time."Re the triangles; Yup, I do do outside triangles and the original purpose was to unwind solid lines back when I used them to avoid any potential stickiness during the glide...a very practical and valid purpose (those who have had solids get "sticky" on them will understand"). Now, the only remaining question is: was doing outside triangles "showboating" in addition to being practical? Well, those who did read my original post would have a pretty good clue as to why I did triangles rather than simple outside loops to unwind the lines (and continue out of habit as much as anything since I've long since abandoned solids as more trouble than they're worth...when I fly which is pretty infrequent the last year or two. Although, for that matter, as you suggested, landing with twists in the lines isn't the best situation even with cables).
Figured it out? Get the hint in the first post? If not reread the section on sustained positive Gs rather than abrupt quick loops to kill the engine and see if a light bulb comes on.
To answer your question, no, I've never had the engine quit in the outside triangles...not once. I do outside triangles on purpose (and at roughly rule book level flight altitude) because: #1 the abrupt tight corners don't last long enough to starve the engine of fuel and therefore you don't risk killing the engine as you would doing sustained G round loops; #2, I do outside triangles rather than outside squares because I "never" do outside triangles in the pattern (ain't none there). For a period of time I did outside squares to clear the lines and my outside squares in the pattern turned to you know what. Simple reason, outside squares at the end of the pattern require significantly less control input because there's several ounces less fuel in the nose of the airplane. If you do as many meaningless outside squares with the CG aft as you do with it forward the chances of getting them just right when it counts are seriously eroded and your scores are predictably reduced...you probably don't have to ask how I know that. On nthe other hand, I've never done an outside triangle for an official score (Al insists there are no such things) so I don't risk screwing up my official patterns by throwing in a set of them after the clover on every flight. I made a conscious competitive decision to routinely do outside maneuvers for a valid purpose and chose to do triangles because it makes sense for the reasons stated.
One can disagree on whether there is value in doing so and I'll respect that difference of opinion. I'm very disappointed, however, if my thoughtfully considered decisions are derided as nothing but showmanship merely because of that difference of opinion.
A p.s. on that subject. You mentioned my cutoff "loops" plural. I doubt very much that you saw me do more than one cut-off loop very often because (as you suggested) I knew my airplane and powertrain and wouldn't bother to do the one necessary loop until it was 90% certain one would do the job.
Denny said: "The cut-off loop ONLY works when the engine is nearly ready to shut off anyway. " Have to disagree again. I don't know how long the engine would normally run after the cutoff loop but several laps is a pretty good guess for a tank of my normal configuration which is deeper than the standard one inch (anywhere from 1.25 to 1.375") If I thought the engine was about to run out of fuel in level flight I would never attempt the cut-off loop because you lose the control of the situation if the engine cut just before or after you begin the entry. The use of the cut-off loop is a calculated tool to provide the advantages (IMHO) that I discussed in my original post.
Denny stated: "It has also been my expereince that IC engines ALWAYS cut-off in the same part of the circel in level flight too." That may be true although I've flown a lot of flights in my life and haven't seen that degree of consistency. In any case it isn't important to me that the engine quits at the "same" place, only that it quit at the right place to allow me to maneuver as necessary to comply with the rule book description of a perfect landing. That's why I want to control the place of cutoff and the amount of energy available to me to place the airplane on the ground where and at what speed I want there.
Which brings up, Ta Da> THE RULES.
Denny said: OK now the controversial part. Typically when the engine shuts off it can easily do it in some any part of the loop and NOT just dead center at the bottom. If the engine quits ANTWHERE but dead cnter bottom, why isn't the Landing score docked say 50%? I mean is a loop part of a smooth gradual descent to a gentle touch-down?
No need to answer, you know what I said is RIGHT, but it will never be scored that way, and frankly I wont lose any sleep over it...O.K. Denny, here's the rule book description with some emphasis added: "13.15. Landing.
A correct landing is judged when the model descends smoothly to land with no bounce or unusual roughness, and without any part of the model other than the landing gear having touched the ground. Main wheel(s) or three-point landings are permissible. The duration of the flight ends when the model rolls to a stop. Maximum 40 points. Minimum 0 points. Note: Illustrations are for anticlockwise flight and are reversed for clockwise flying.
Errors: An error is committed whenever the model bounces or when any part of the model other than the landing gear touches the ground. A crash, or a flip over, a belly or upside down landing receives no marks. An error occurs each time the model deviates from a smooth descent. Any unusual circumstances, outside the pilot’s control, which may have caused one of the above mentioned errors will be taken into consideration by the judges. Note: It is permissible to extend (by whipping) the descent, to achieve the minimum two (2) laps between maneuvers, to maintain eligibility for pattern points."
(By the way, notice the reference at the end to whipping to retain pattern points! OOOOOPS!)
Note the absence of your word "gradual" in the rule book description of the correct execution of the landing. You have a right to a personal interpretation of the words but not your own words!
I have (and have watched others) on numerous occasions flown smooth descents and landings from out of a cut--off loop in high winds that all took place in roughly three quarters of a lap from flame out at 45 or so degrees to touchdown. There was nothing gradual in the rate of descent to that smooth touchdown but the descent was smooth and ended in a greased on "wheel" landing at high speed. There is absolutely nothing inconsistent with the rule book in my description of that maneuver...and a deduction of 20 points for such a properly planned and executed maneuver would be a crime. Success in aviation is primarily the result of proper utilization of energy. The landing just described is a classic case of outstanding energy management
Now, if you somehow managed in a high wind to do the cut-off loop and have the engine and prop stop during the climb of the loop I would grant you that points should be deducted but the deduction shouldn't really be more than any other "pitch up" during the descent such as those that occur routinely when somebody whips a deadstick ship at slow speed back into the wind and balloons. I personally don't believe I've ever seen a properly executed cut-off loop that managed to stop the prop prior to descending down the back side of the loop...which for any competent pilot is a "smooth" transition to the gliding state. For that to happen the engine would almost need to have flamed out prior to the entry in which case the pilot would have earned whatever few bones get tossed his way by the judges.
At any rate, it's a fun debate. I'll be happy if others review our respective positions and consider the merits and/or demerits of each and come to their own conclusions. I can only hope they'll believe I didn't just make up all the above rhetoric merely to fend off charges of showboating. I really believe that stuff, believe it or not!
Merry, merry again, my friend.
Ted
Topic: Cut Off Loop (Read 5677 times)