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FAI P21 - trainwreck sequence

Old 11-18-2019, 11:12 AM
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jim woodward
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Default FAI P21 - trainwreck sequence

Gents - for your consideration. I believe strongly that P21 is a train-wreck of a sequence, due to its flow. In general, the turnarounds finish too close to center. While there are some nuisances; the worst part starts from the Figure Z, Comet, 4-Point Roll. I have less satisfaction flying this sequence than any other USA Pattern or FAI P sequence, at anytime.

Are there any options to solicit input & correct this sequence? I don't think it is possible that a group of pilots seriously flew this prior to assigning, and believed it would be a good sequence. Perhaps I am the only one that feels this way.

Thank You,
Jim W.
Old 11-18-2019, 11:15 PM
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chuck4816s
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Hence why I fly masters...
Old 11-20-2019, 05:17 AM
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flywilly
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Hi Jim,
Unfortunately, I really doubt there will be changes made to the sequence. You can try contacting the US FAI representative (should be listed in the AMA magazine - used to be Ron Chidgey). The two year rules cycle for the FAI would be better if they announced the sequences 2 years in advance (so we would have seen the P21 and F21 2 years ago) as provisional sequences to allow for pilot feedback. Probably more likely to get that change implemented than change an existing sequence. I agree about the turnarounds and the sequence in general. I guess with slower, constant speed they feel that less distance between maneuvers is needed. Neither pilot nor judge friendly, IMHO.
-Will
Old 11-21-2019, 06:36 PM
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Don Szczur
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Jim,

Come into Figure Z slow with tight radius just past center, making the maneuver not too tall at the top as a result. Start the comet later, make the down line shorter and resulting 3/4 loop high and tight which brings it down with enough room to do straight and level before the 4 point.

See you,
Don
Old 11-21-2019, 07:46 PM
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jim woodward
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Thanks Don,

I'll give the later-high/tight comet approach a try. Hope all is going well for you.

Jim
Old 12-16-2019, 02:52 PM
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I haven't done it for the past sequence but given the discussion I might do it for P21, that is draw the sequence in AutoCAD. Drawing up the sequence in CAD is a good way of figuring out how a sequence can fit together and what sizes things may need to be flown.

I started doing this after reading something on the control line stunt subject where somebody was wanting to animate a stunt sequence for a project and realised some of the geometric judging criteria could not be met on some maneuvers by an aircraft flying on a hemisphere.

For the rough estimate speed I fly I try to pick two radii for corners and part loops and see how it fits together. For me a good starting point for a loop radius is one where I can comfortably integrate a 1/2 roll in a 1/4 loop section without it looking forced. Here's the drawing I did for P15, just looking at how things fit in a "typical" 60 degree box at 150m with a 40m baseline height. Not many maneuvers could be flown to the full top height in that one if you wanted reasonably consistent radii and everything to fit.

Old 12-19-2019, 06:15 PM
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Originally Posted by Don Szczur View Post
Jim,

Come into Figure Z slow with tight radius just past center, making the maneuver not too tall at the top as a result. Start the comet later, make the down line shorter and resulting 3/4 loop high and tight which brings it down with enough room to do straight and level before the 4 point.

See you,
Don
Are you sure performing the loop high gives you more room for the 4 point roll?


Comet Loop Low vs High. Much more distance from exit to centre when performing the loop low.

Last edited by bjr_93tz; 12-19-2019 at 06:18 PM.
Old 12-19-2019, 06:17 PM
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Going all the way to the top of the box simply isn't going to work here.

That Z then Comet probably needs to be flown like "4" to make room for the 4 point roll.
Old 12-22-2019, 04:06 PM
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Don Szczur
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Loop higher meaning picture number 3 with a smaller radius (than I was originally flying). The loop is visually "higher" at least that what was going through my mind when working the maneuver into the sequence flow. I am sure the sequence will present fine at the competitions. See you in Muncie!
Old 01-22-2020, 04:05 PM
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I found the transition from P19 to P21 was difficult even though there were no really large manoeuvres that had to be centred like the Cuban 8 and Double Key in P19.

As regards the Comet to 4 pt roll, I seem to remember that there was a similar issue with a Comet ( entered from low and climbing at 45 deg into a 6 sided loop. What worked then was to fly the manoeuvre based on the roll in the middle of each line and not centreing the whole manoeuvre. If you did the latter, you barely had time to get level before entering the 6 sided loop. The same approach then, an asymmetric manoeuvre but with the rolls centred worked for me then and works now for the Comet to 4 pt roll. Yes, you don't have much time but then again it's not impossible and it can be made to look good.

I agree with Don that you need to keep the height of the Fig Z down and a tight entry and exit loop helps in that regard. Provided both are the same radius it should cause the judge to downgrade you.

I find the transition from the Split S into the Golf Ball also poses the same problem and again a tightish radius for the Split S loop helps me to make the manoeuvre not look as if it's rushed. Of course, the trick is to get all these points right on the flight that counts! Something I'm still working on!
Old 01-22-2020, 04:11 PM
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Originally Posted by barnowljenx View Post
I found the transition from P19 to P21 was difficult even though there were no really large manoeuvres that had to be centred like the Cuban 8 and Double Key in P19.

As regards the Comet to 4 pt roll, I seem to remember that there was a similar issue with a Comet ( entered from low and climbing at 45 deg into a 6 sided loop. What worked then was to fly the manoeuvre based on the roll in the middle of each line and not centreing the whole manoeuvre. If you did the latter, you barely had time to get level before entering the 6 sided loop. The same approach then, an asymmetric manoeuvre but with the rolls centred worked for me then and works now for the Comet to 4 pt roll. Yes, you don't have much time but then again it's not impossible and it can be made to look good.

I agree with Don that you need to keep the height of the Fig Z down and a tight entry and exit loop helps in that regard. Provided both are the same radius it should cause the judge to downgrade you.

I find the transition from the Split S into the Golf Ball also poses the same problem and again a tightish radius for the Split S loop helps me to make the manoeuvre not look as if it's rushed. Of course, the trick is to get all these points right on the flight that counts! Something I'm still working on!
Making the Z too small could be a potential down grade if it's too much different in size compared to the other manouvres.
Old 01-23-2020, 12:55 AM
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drac1, I have fitted on-board monitoring to my aircraft specifically to check what height I reach. If I fly a large diameter entry to the Fig Z by the time I reach the top my altitude is in the range 1100 to 1200 feet. That puts me well out of the top of the box (150 mtr x tan 60 x 3.28 = 850 ft). So that will also result in a down grade. Flying relatively short straight before flying a tight entry to the Z allows time for the roll and then a tight exit and that puts me at between 850 and 900 ft. So, I don't think that there is a danger of a downgrade on that basis.
Old 01-23-2020, 02:20 AM
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Originally Posted by barnowljenx View Post
drac1, I have fitted on-board monitoring to my aircraft specifically to check what height I reach. If I fly a large diameter entry to the Fig Z by the time I reach the top my altitude is in the range 1100 to 1200 feet. That puts me well out of the top of the box (150 mtr x tan 60 x 3.28 = 850 ft). So that will also result in a down grade. Flying relatively short straight before flying a tight entry to the Z allows time for the roll and then a tight exit and that puts me at between 850 and 900 ft. So, I don't think that there is a danger of a downgrade on that basis.
Like I said above, if the Z is noticeably different in size compared to the other manouvres, it should be down graded.

Last edited by drac1; 01-23-2020 at 04:29 AM.
Old 01-23-2020, 02:32 PM
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jim woodward
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1200' for sure is possible. I flew an F21 sequence the other day with a borrowed altimeter, and after zeroing, indicated 1199'. It wasn't even an overtly large sequence.
Jim
Old 01-23-2020, 03:14 PM
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Seriously gents, if you don't have CAD just grab a compass and set square and actually draw what we're supposed to be flying.

Not many manoeuvres can be flown to the top of the box without being ridiculously huge or encroaching into the next maneuver. A Double Immelman takes nearly the WHOLE box if you want to fly it to the top and a Cuban Eight simply doesn't fit in the box if you take it to the top. Given consistent maneuver size is supposed to be considered, 3/4 way to the top of the box is a very good compromise for consistent height for things, except for the one or two odd, tall and skinny things such as entering a stall turn from mid height.


Old 01-23-2020, 04:51 PM
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Originally Posted by bjr_93tz View Post
Seriously gents, if you don't have CAD just grab a compass and set square and actually draw what we're supposed to be flying.

Not many manoeuvres can be flown to the top of the box without being ridiculously huge or encroaching into the next maneuver. A Double Immelman takes nearly the WHOLE box if you want to fly it to the top and a Cuban Eight simply doesn't fit in the box if you take it to the top. Given consistent maneuver size is supposed to be considered, 3/4 way to the top of the box is a very good compromise for consistent height for things, except for the one or two odd, tall and skinny things such as entering a stall turn from mid height.
I'll be doing what I usually do. Fly at 175m and make it fit 😬
Old 01-24-2020, 02:34 AM
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Originally Posted by drac1 View Post
I'll be doing what I usually do. Fly at 175m and make it fit 😬
It's a cruel fact of geometry that flying closer in or further out doesn't change some relationships. No matter how far or close you fly, a Cuban Eight flown to the top of the box must be out of the box at each end.

For sure, we can manipulate a few things legally within an individual maneuver, but sometimes when you draw things up it's easier to see some fixed relationships. It's like those four drawings of the Figure "Z" into the Comet. Two things that jumped out at me when I drew that was that in order to give yourself plenty of room for the rolls following the Comet, the 3/8 loop to 45 in the Z, must start pretty close to centre and the 1/8 loop down to 45 for the Comet must start pretty close to centre as well. If they don't and the exit the Comet has plenty of room before the centre for the rolls, then the geometry for the Comet must have been a bit off. If somebody flys 30 degree past centre before pushing into the Comet then they're in trouble for the rolls or willing to take the points hit for the Comet geometry.

I badly need to get out to the field and push some fuel though my 200cdi. The 200cdi has turned out to be less plug and play as I had hoped for so far as the Aries 07 airframe hasn't responded well (trim and mix wise) to the propeller change. I really need a few quiet days to get the engine running better and sort the trimming out.
Old 01-24-2020, 02:52 AM
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Originally Posted by bjr_93tz View Post
It's a cruel fact of geometry that flying closer in or further out doesn't change some relationships. No matter how far or close you fly, a Cuban Eight flown to the top of the box must be out of the box at each end.

For sure, we can manipulate a few things legally within an individual maneuver, but sometimes when you draw things up it's easier to see some fixed relationships. It's like those four drawings of the Figure "Z" into the Comet. Two things that jumped out at me when I drew that was that in order to give yourself plenty of room for the rolls following the Comet, the 3/8 loop to 45 in the Z, must start pretty close to centre and the 1/8 loop down to 45 for the Comet must start pretty close to centre as well. If they don't and the exit the Comet has plenty of room before the centre for the rolls, then the geometry for the Comet must have been a bit off. If somebody flys 30 degree past centre before pushing into the Comet then they're in trouble for the rolls or willing to take the points hit for the Comet geometry.

I badly need to get out to the field and push some fuel though my 200cdi. The 200cdi has turned out to be less plug and play as I had hoped for so far as the Aries 07 airframe hasn't responded well (trim and mix wise) to the propeller change. I really need a few quiet days to get the engine running better and sort the trimming out.
Fact or not, flying further out is easier to make it fit. Easier to make it looked not rushed etc.
Old 04-12-2020, 07:34 PM
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I have not flown P21 yet Jimbo but does not look that bad the Zee seems easy to get into the next maneuver. I do not like the look of the current trend of aircraft. Except for what Mr. Bryan Hebert designs. T cannalizers should be banned. Since I never flew F's in recent years I believe that level of difficulty should not be introduced at local contests to keep participation levels up. Then again as someone commented one could fly AMA.

Last edited by Freddy; 04-12-2020 at 08:00 PM. Reason: Update
Old 04-14-2020, 08:03 PM
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Originally Posted by barnowljenx View Post
drac1, I have fitted on-board monitoring to my aircraft specifically to check what height I reach. If I fly a large diameter entry to the Fig Z by the time I reach the top my altitude is in the range 1100 to 1200 feet. That puts me well out of the top of the box (150 mtr x tan 60 x 3.28 = 850 ft). So that will also result in a down grade. Flying relatively short straight before flying a tight entry to the Z allows time for the roll and then a tight exit and that puts me at between 850 and 900 ft. So, I don't think that there is a danger of a downgrade on that basis.
Case in point see my other reply below in this thread. Reminder of the 400 foot impractical ceiling limit the FAA is trying to force down our throats and the AMA has to continue to battle to not lump us in with the drones.
1200 feet! Now that is way too high and in general aviation territory.
Old 04-15-2020, 01:12 AM
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Hi Freddie, luckily, I live in the UK where the Government minister responsible has taken a different view and provided the aircraft is not heavier than 7 Kg, does not have more than one rotor, and remains in direct unaided vision, you have demonstrated your understanding of air law, have registered with the CAA and you are a member of one of 4 model aircraft associations, there is no specific height limit other than remaining outside controlled airspace. The onus is on the model pilot to avoid conflicts with full size aviation. The rules in the UK before the drone regs was exactly that anyway apart from not specifying single rotor. So, 1,200 ft in the UK, and probably a lot of other countries, is not considered way too high. I think the thermal soaring brigade would agree with that as well.
You are quite right to point out that 400 ft makes flying precision aerobatics impossible. Hope your FAA can be persuaded to move away from that limitation.
Old 04-15-2020, 04:56 PM
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Don Szczur
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I come into the figure Z with relatively low airspeed, then it allows a reasonable radius at the bottom and top, with time to execute the roll element on the 45. This keeps the size of the maneuver consistent with other sequence maneuvers sizes but more importantly helps to manage the comet and subsequent 4 point. Ditto for the half 8 sided loop with half rolls in F sequence which precedes the center rolling loop.

I found the P sequence quite enjoyable. The F sequence is quite challenging, which is good. It really helps motivate to focus on practice this year. The very mild weather in January and February enabled to get in a lot of practice before the stay at hope orders were issued. I hear there are some folks on RF simulator practicing together, if anyone is interested.

WRT aircraft- our year 2012 Pegasus gets through P and F, so the sequences have not outgrown the aircraft. Just got the 2020 F3A team selection program in email yesterday. Hope to see you at the NATS if it can happen.
Old 04-15-2020, 05:06 PM
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Thank you for your input and feedback from the UK. You guys are logical independent thinkers, hence Brexit!
I know all about the FAA/EASA/ANAC/Transport Canada/the old CAA and others as I am still a working aeronautical engineer with 30 plus years of of FAA Part 25 aircraft design and certification experience including FAA Part 121 airline operational experience.
The drone idiots who taunt airliners at airports etc. should be locked up and spoiled it for our dear hobby. I am into RC since childhood 1975.
Old 04-22-2020, 04:53 PM
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We can thank our drone friends for this. At least the AMA is lobbying hard on behalf of the RC community.

107.51 Operating limitations for small unmanned aircraft.

A remote pilot in command and the person manipulating the flight controls of the small unmanned aircraft system must comply with all of the following operating limitations when operating a small unmanned aircraft system:

(a) The groundspeed of the small unmanned aircraft may not exceed 87 knots (100 miles per hour).

(b) The altitude of the small unmanned aircraft cannot be higher than 400 feet above ground level, unless the small unmanned aircraft:

(1) Is flown within a 400-foot radius of a structure; and

(2) Does not fly higher than 400 feet above the structure's immediate uppermost limit.

(c) The minimum flight visibility, as observed from the location of the control station must be no less than 3 statute miles. For purposes of this section, flight visibility means the average slant distance from the control station at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be seen and identified by night.

(d) The minimum distance of the small unmanned aircraft from clouds must be no less than:

(1) 500 feet below the cloud; and

(2) 2,000 feet horizontally from the cloud.

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