Flight B/C

[coachchuckaahs]

Heya!

Has anyone here used crusty old cya? Wondering whether I should throw away a bottle that's a couple of months old. At what point does CA become "bad" or unusable? I wanted to do some building this weekend but I don't have any other superglue

Try some. If it kicks off quickly (thin CA) it is fine. I have bottles as much as a year old and still work. Generally the first sign of CA going bad for us is either curing quickly on the surface we dish it out on (*usually a margarine lid), of constant clogging of our capillary applicator.

If the bottle has been around that evil "kicker" too much it could also be prone to being gummy and setting off in your tools.

Coach Chuck

[pumptato-cat]

Hi again! Back with more questions.

So... I'm back to tackling the air conditioning issues. I don't want to roll in with confidence and fly 0:36 again... That was quite an awful feeling. Never again(hopefully)! Here are some plans I have to hopefully avoid repeating last season.
1) Circle Size and other tidbits
I'm going to experiment with setting a smaller turn circle(13-17ft) and making other small adjustments(cg forward, build heavier than 8g, etc) on a backup plane to prep for regionals(likely the same 19' death chamber as last year with the lovely hairblower AC). I'm mostly worried about the draft and I think the efficiency loss doesn't outweigh the benefits of an increased chance of a flight ending--I know people say larger circles are more efficient, but how large is the time benefit? As of now my large-circle flights hit walls because the plane drifts from air conditioning. I have never had a complete flight in competition because the plane always hits vents, so this is kinda a serious problem. I'm just confused on how everyone else seems okay with AC(Another recent commenter mentioned that they fly 2:00-2:30 in AC which is incomprehensible to me, as I've only gotten ~1:20...) while one puff from a vent at my planes cause wobbling and instant death.

I'm just salty about 2023 states and feel the need to redeem myself this year... I feel like the practice I do in still air is wasted because every flight I do in a ventilated area flunks immediately no matter how much data I log or how many settings I try. This is also likely my last scioly season so I'm desperate to redeem myself at states, haha!

2) On Turning and other concepts
Can anyone point me to some links on the reasoning behind the statement that tighter turns are less efficient? I read somewhere that it has to do with more energy being put into turning instead of sustaining flight but I'd like some in-depth information on general information such as that. I feel like my knowledge on actual flying is insufficient when it comes to reasoning behind topics(like, why are some fins(rudder fins? I don't know the term) under or above the motor stick? Why does tilting the stab so the right tip is under the left tip cause turn?, etc. I guess I want to better understand the reasoning behind the designs I fly so I can feel confident modifying them). I've been reading INAV and I have a copy of "Flying Indoor Model Airplanes" but was wondering if anyone knew of any other sources. Hopefully that makes sense.

Whoops, this got longer than I expected. Thanks for reading this far, and any help would be much appreciated =)

[bjt4888]

Hi again! Back with more questions.

So... I'm back to tackling the air conditioning issues. I don't want to roll in with confidence and fly 0:36 again... That was quite an awful feeling. Never again(hopefully)! Here are some plans I have to hopefully avoid repeating last season.
1) Circle Size and other tidbits
I'm going to experiment with setting a smaller turn circle(13-17ft) and making other small adjustments(cg forward, build heavier than 8g, etc) on a backup plane to prep for regionals(likely the same 19' death chamber as last year with the lovely hairblower AC). I'm mostly worried about the draft and I think the efficiency loss doesn't outweigh the benefits of an increased chance of a flight ending--I know people say larger circles are more efficient, but how large is the time benefit? As of now my large-circle flights hit walls because the plane drifts from air conditioning. I have never had a complete flight in competition because the plane always hits vents, so this is kinda a serious problem. I'm just confused on how everyone else seems okay with AC(Another recent commenter mentioned that they fly 2:00-2:30 in AC which is incomprehensible to me, as I've only gotten ~1:20...) while one puff from a vent at my planes cause wobbling and instant death.

I'm just salty about 2023 states and feel the need to redeem myself this year... I feel like the practice I do in still air is wasted because every flight I do in a ventilated area flunks immediately no matter how much data I log or how many settings I try. This is also likely my last scioly season so I'm desperate to redeem myself at states, haha!

2) On Turning and other concepts
Can anyone point me to some links on the reasoning behind the statement that tighter turns are less efficient? I read somewhere that it has to do with more energy being put into turning instead of sustaining flight but I'd like some in-depth information on general information such as that. I feel like my knowledge on actual flying is insufficient when it comes to reasoning behind topics(like, why are some fins(rudder fins? I don't know the term) under or above the motor stick? Why does tilting the stab so the right tip is under the left tip cause turn?, etc. I guess I want to better understand the reasoning behind the designs I fly so I can feel confident modifying them). I've been reading INAV and I have a copy of "Flying Indoor Model Airplanes" but was wondering if anyone knew of any other sources. Hopefully that makes sense.

Whoops, this got longer than I expected. Thanks for reading this far, and any help would be much appreciated =)

Cat,

I'll take a cut at some of your questions.

There’s AC and then there’s bad AC. Doing 2:00-2:30 last year in Div C with AC on either means that the blowers weren’t that bad or the team was lucky. For example at last year’s Michigan States, for the first time ever, they didn’t turn off blowers. The gym was old though and didn’t have bad blowers, but the up vs. down vs. sideways air was almost random.

Poorly trimmed, fast flying, airplanes will bore right through bad air to a certain extent and a number of airplanes like this did about two minutes that day. The best flight of the day was a completely lucky, massive overtorque launch that hit the ceiling about five times and just kept bouncing back towards the good areas of the gym; they flew over three minutes but had deductions, possibly for an incomplete or missing log. My teams watched people fly all day and found what appeared to be the best part of the gym and flew their regular good trim.

Unfortunately, the relatively good part of the gym also had slightly rising air and caused my teams to have ceiling hits at about 55 seconds (22 ft ceiling and we should have been at 20 ft at 1:20). Three of the six airplanes on my coached teams were relatively lucky and had lucky bounces and flew high 2:30’s and low 2:40’s to get 1st, 2nd and 6th. The other three airplanes got stuck in the ceiling (something we never never do) or had bad bounces and wall hits and got flights of 55 sec to 2:20.

So, for this year’s Div C Freedom Flight airplane that you are flying right now, what I’d do if I knew we were competing with bad blowers is move the CG forward (maybe about 1.625” or even 1.75” forward of rear wing post) add a little decalage (maybe 3/16” wing incidence, or until it stalls, instead of the 1/8” recommended) and tighten the flight circle to about 15-18 ft with additional tailboom offset (works better than stab tilt at high speed). Remember that with additional tailboom offset you might also need a little more left wing washin to climb smoothly. On the day of your competition, try to fly a practice flight in the competition gym early in the day. Pick what looks like the best launch location and attempt to fly about 12-13 ft high (full winding with backoff to get this high) to determine whether the blowers are causing more rapid than typical climb and height or slower than typical climb and height. If you have time before the practice session gets crowded, try another likely good launch location in the same way.

Then, when competing, wind up full and backoff to a torque that compensates for what you discovered in practice so that you get a climb to within 2 ft of ceiling (safe margin) and then launch in the same spot that you practiced that got you the best result. This is what we do when facing blowers, but remember that we did this at last year’s Michigan States and still had 50% of flights fail. If you are a little lucky and determine rising air vs. depressed air and compensating launch torque and good launch location correctly, maybe one of your flights will be good.

I’ll answer some of your other questions on Wednesday. Got to cut some rubber for a Middle School practice tomorrow.

Brian T

[jgrischow1]

Recently supervised a mid-sized Division B tourney in NW Ohio. Mostly northern Ohio and Southern Michigan teams. Top times were around 2:30; lot of times in the 1:45-2:05 range. 27' gym to ceiling; rafters around 23 maybe.

-Way more teams have figured out boxes that fit the dimensions compared to last year, but many teams still had boxes that were too big. However, since this was early season, I allowed them with a finger wag as long as the plane would fit in standard dimensions.

-Biggest issue was using last year's rules...many had rubber that was way too heavy. Again, trying to be nice, I allowed them to cut it down to size. Many also had design logs that were required last year but not this year.

-Many teams had incomplete data logs...biggest issue was not having 6 parameters. I don't count date or "flight number" as a parameter. I would also suggest teams put each parameter in a separate column and make it obvious to the supervisor that you have 6.

-Teams did a better job than last year of thinking where they should stand. Way fewer collisions with the wall. We had a couple of planes stuck in the bleachers and a few stuck in the rafters. A team brought their long pole; unfortunately, I don't have one.

-Influence of coach Brian was obvious with some teams...they knew what they were doing and had lots of data for each rubber motor.

-Way too many coaches and parents hovering way too close to the kids...I need to do a better job of cordoning off the competition area. One team flat out admitted their coach built their plane.

Overall, way better performances than when I supervised last year (mid-January.) Looking forward to see what lies ahead in this event. Thankful to the coaches who post on here.

[pumptato-cat]

-Way too many coaches and parents hovering way too close to the kids...I need to do a better job of cordoning off the competition area. One team flat out admitted their coach built their plane.

Overall, way better performances than when I supervised last year (mid-January.) Looking forward to see what lies ahead in this event. Thankful to the coaches who post on here.

Yeah, the coaching thing is a real issue. Last year at states a girl's parents were hovering around her and watching every single trim flight(two things wrong: a) parents, b) trim flights at that tournament were supposedly illegal) while advising her on everything including where to stand.
It's infuriating and parents need to remember that this is a competition for their kids, not themselves--although I suspect that the common problem is likely with the students more than the parents.

Thank you for the information, especially the flight times! I'm glad to hear that quality of tournaments are improving.

[coachchuckaahs]

Cat:

I agree with Coach Brian that every HVAC situation is different. It is important to "read the room" while others fly to make your plan for success. Understand what the air does where. And this is true whether HVAC is on or off. At Cornell Nationals, there were so many spectators crammed in to one end of the room that it created substantial lift at that end, sink at the other and, and strong drift lengthwise at the ceiling, even though AC was off.

All you can do is improve stability. I would NOT recommend building heavy to do that. But yes to moving CG forward (it does not take much) and adjusting wing incidence to re-optimize. On Div B this year we tried a small 3mm CG adjustment rearward as we thought the plane was perhaps overly stable (more drag). We went from a 6" drop on girder touch to a 9 foot drop!. So a little goes a long way.

On circling, the stab tilt works because we use a lifting stab (airfoil). So if the stab is flat it lifts straight up. If the stab is slightly tilted toward the right, it now lifts mostly up, but slightly to the right. This pushes the rear of the plane right, causing a left circle. Putting in more rudder (tail offset) presents the right wing to the airflow more, which will roll the plane slightly to the left, making the lift form the wing pull the plane to the left. On either case, you are trading some lift for turn, so therefore less efficient. In addition as you put in rudder, presenting the right wing slightly sideways, there is a, increase in drag. That said, it is indeed better to complete a flight with some compromise than to get redirected into the wall. In most cases we keep a circle size suitable for about 2/3 the width of a basketball court, and we don't generally increase that for larger facilities (there are always obstacles). We have on occasion tightened up the circle (ballroom with AC on, 50'x50') to accommodate less than favorable facilities.

Last year our State initially had Div B in a "hallway" that was only 10' wide (but it was something like 90' long!). In this case I don't think there would have been a good answer on circling! The best answer was to address it before hand and convince State that the planes need to circle. Fortunately they listened to the appeal and we flew with the C div in an auditorium. Still not ideal, but better than a hall!

I think you are on the right path to address the situation, including tighter circle and more stable plane.

Coach Chuck

[pumptato-cat]

Short discussion from Discord I thought would be helpful:
"Many organizers don't read the rules until day of. I have found it important to keep asking, and to point out that the rules require teh measurements be distributed ahead of the event. If a nearby event (Regionals and States in NM), I would personally go to the facility, measure with a laser, and send the measurements to the organizers. Should not come to that, but often when they release measurements it is not at all accurate or even representative of the suitable flying area.
I keep a laser distance finder in the tool box, and if I am not ES, I make sure the kids know how to use it, and how to adjust their winding and rubber if it is different than expected. Last year we had a whole table of rubber selection and torques because there was so much uncertainty at State. And, yes, even if they say no AC, you need to know what to change last minute if the AC is on." -Coach Chuck