Duration

User avatar
eta150
Member
Member
Posts: 269
Joined: Wed Mar 11, 2009 3:48 pm
Division: Grad
State: PA
Has thanked: 0
Been thanked: 0

Re: Duration

Post by eta150 »

sr243 wrote:Can someone tell me how to get 2 minute+ flight times. I have tried different length rubber bands and such but I am stuck at 1:45. Using a 1.75g rubber band, I use about 800 winds and has about 150-200 winds left. It only get 1:40 on a 25 feet ceiling. Is it spinning too fast (avg 6.5 winds per second)? When I use a 1.65g rubber band, I get 650 winds and about 1:35 with <100 winds left. This has a slightly slower avg winds per second, but still seems high. Is there a way to slow down the winds at the beginning? It seems like the rubber band just doesn't last long enough to get past 2 minutes for me even though it has good lift.
What's the helicopter's mass? Helical blades? Balance? Fixed or free top or bottom rotors? Rubber band width?
You have to give us something more to go on here.
#ACESWILD
sr243
Member
Member
Posts: 138
Joined: Tue Jan 15, 2008 4:53 pm
Division: C
State: WI
Has thanked: 0
Been thanked: 0

Re: Duration

Post by sr243 »

eta150 wrote:
sr243 wrote:Can someone tell me how to get 2 minute+ flight times. I have tried different length rubber bands and such but I am stuck at 1:45. Using a 1.75g rubber band, I use about 800 winds and has about 150-200 winds left. It only get 1:40 on a 25 feet ceiling. Is it spinning too fast (avg 6.5 winds per second)? When I use a 1.65g rubber band, I get 650 winds and about 1:35 with <100 winds left. This has a slightly slower avg winds per second, but still seems high. Is there a way to slow down the winds at the beginning? It seems like the rubber band just doesn't last long enough to get past 2 minutes for me even though it has good lift.
What's the helicopter's mass? Helical blades? Balance? Fixed or free top or bottom rotors? Rubber band width?
You have to give us something more to go on here.
3.5-3.55g mass, without clay, it is around 3g. Helical blades, with curved ribs. fixed bottom, free top rotor. 1/8 inch rubber band length. 30 cm motor stick. Anything else?
sciolymeister
Member
Member
Posts: 4
Joined: Sun Mar 11, 2012 12:52 pm
Division: C
State: ME
Has thanked: 0
Been thanked: 0

Re: Duration

Post by sciolymeister »

sr243 wrote:Can someone tell me how to get 2 minute+ flight times. I have tried different length rubber bands and such but I am stuck at 1:45. Using a 1.75g rubber band, I use about 800 winds and has about 150-200 winds left. It only get 1:40 on a 25 feet ceiling. Is it spinning too fast (avg 6.5 winds per second)? When I use a 1.65g rubber band, I get 650 winds and about 1:35 with <100 winds left. This has a slightly slower avg winds per second, but still seems high. Is there a way to slow down the winds at the beginning? It seems like the rubber band just doesn't last long enough to get past 2 minutes for me even though it has good lift.
The case may that your ceiling is too low. We moved our testing location to a 3 story high gym area and our time improved a lot. Our old helicopter had also a similar time because the blades spun too fast, so to alleviate the problem we actually ADDED weight to the helicopter (I know it seems counterintuitive, but our helicopter time increased by a concsistent 15 seconds.)
User avatar
mrsteven
Exalted Member
Exalted Member
Posts: 815
Joined: Sun Mar 13, 2011 5:40 pm
Division: C
State: IL
Has thanked: 0
Been thanked: 0

Re: Duration

Post by mrsteven »

sciolymeister wrote:
sr243 wrote:Can someone tell me how to get 2 minute+ flight times. I have tried different length rubber bands and such but I am stuck at 1:45. Using a 1.75g rubber band, I use about 800 winds and has about 150-200 winds left. It only get 1:40 on a 25 feet ceiling. Is it spinning too fast (avg 6.5 winds per second)? When I use a 1.65g rubber band, I get 650 winds and about 1:35 with <100 winds left. This has a slightly slower avg winds per second, but still seems high. Is there a way to slow down the winds at the beginning? It seems like the rubber band just doesn't last long enough to get past 2 minutes for me even though it has good lift.
The case may that your ceiling is too low. We moved our testing location to a 3 story high gym area and our time improved a lot. Our old helicopter had also a similar time because the blades spun too fast, so to alleviate the problem we actually ADDED weight to the helicopter (I know it seems counterintuitive, but our helicopter time increased by a concsistent 15 seconds.)
well, a higher ceiling in most cases will improve time as you have more decent time. I added a good 30-40 seconds from a stairwell to the armory in U of I

WEIGHT is the enemy, well really its gravity but weight makes it worse, don't add unnecessary weight where its unneeded. Adding weight to an unstable helicopter can make it fly more true given that the fixtures are true as well. However, if it seems to fly true already adding mass to it is INEFFECTIVE and just hurts you.

if you state competition is in a large warehouse type thing like the armor or indoor football stadium 1:40 + decent will still be an excellent time and place in some states. The OH/NJ/IL/... crowds not so much but in some less competitive states its possible.

Decent time = <3
2011 Helicopters State Runner-up
2012 Helicopters State Champion
2013 Robot Arm State Champion
sr243
Member
Member
Posts: 138
Joined: Tue Jan 15, 2008 4:53 pm
Division: C
State: WI
Has thanked: 0
Been thanked: 0

Re: Duration

Post by sr243 »

thanks, I just want to work on helicopter a bit more before states as I haven't really touched it since regionals. I also realized that the last 50 or so winds after 750 don't seem to add much time. It add less than 5 seconds which is okay, but 800 winds seems like the maximum I can go. So I do not think I can add time by getting more winds, yet I do not know how people can get more than 2 minutes when my rubber band doesn't even spin for over 2 minutes (spinning at 1 rps doesn't count). Doesn't seem like there is much I can do at this point, but I just want to improve my helicopter since it is my best event(1st at regionals).
alecfxl
Member
Member
Posts: 21
Joined: Tue Apr 29, 2003 9:23 am
Has thanked: 0
Been thanked: 0

Re: Duration

Post by alecfxl »

sr243 wrote:thanks, I just want to work on helicopter a bit more before states as I haven't really touched it since regionals. I also realized that the last 50 or so winds after 750 don't seem to add much time. It add less than 5 seconds which is okay, but 800 winds seems like the maximum I can go. So I do not think I can add time by getting more winds, yet I do not know how people can get more than 2 minutes when my rubber band doesn't even spin for over 2 minutes (spinning at 1 rps doesn't count). Doesn't seem like there is much I can do at this point, but I just want to improve my helicopter since it is my best event(1st at regionals).
I'm assuming your helicopter climbs fast (sorry I didn't get to see it at Regional because I was helping with an event). You may want to increase rotor size/pitch to slow the rotation without sacrificing lift. Another thing you can do is decrease rubber length if it doesn't fully unwind. I know you did well but FYI, Boyceville had 2:30+ at their invite. I also have some additional info if you want to PM me.
User avatar
eta150
Member
Member
Posts: 269
Joined: Wed Mar 11, 2009 3:48 pm
Division: Grad
State: PA
Has thanked: 0
Been thanked: 0

Re: Duration

Post by eta150 »

sciolymeister wrote:
sr243 wrote:Can someone tell me how to get 2 minute+ flight times. I have tried different length rubber bands and such but I am stuck at 1:45. Using a 1.75g rubber band, I use about 800 winds and has about 150-200 winds left. It only get 1:40 on a 25 feet ceiling. Is it spinning too fast (avg 6.5 winds per second)? When I use a 1.65g rubber band, I get 650 winds and about 1:35 with <100 winds left. This has a slightly slower avg winds per second, but still seems high. Is there a way to slow down the winds at the beginning? It seems like the rubber band just doesn't last long enough to get past 2 minutes for me even though it has good lift.
The case may that your ceiling is too low. We moved our testing location to a 3 story high gym area and our time improved a lot. Our old helicopter had also a similar time because the blades spun too fast, so to alleviate the problem we actually ADDED weight to the helicopter (I know it seems counterintuitive, but our helicopter time increased by a concsistent 15 seconds.)
Honestly, I don't think ceiling height really matters for practice. You'll only be gaining time on the descent, so I don't know how much the height matters. How's the balance of the helicopter? Does it wobble a lot?
#ACESWILD
sr243
Member
Member
Posts: 138
Joined: Tue Jan 15, 2008 4:53 pm
Division: C
State: WI
Has thanked: 0
Been thanked: 0

Re: Duration

Post by sr243 »

Overall, it is pretty stable. The clay on the bottom helps stablize it. When it hits the ceiling, it may move about 10-20 cm over 30 seconds. I am going to test how long the rubber band takes to unwind 800 winds; I wonder if that is the problem.
User avatar
eta150
Member
Member
Posts: 269
Joined: Wed Mar 11, 2009 3:48 pm
Division: Grad
State: PA
Has thanked: 0
Been thanked: 0

Re: Duration

Post by eta150 »

With that many winds left over, you're probably losing time by using that much rubber. The extra winds aren't doing much for you, and the weight penalty isn't good either.
#ACESWILD
twototwenty
Exalted Member
Exalted Member
Posts: 292
Joined: Thu Mar 24, 2011 10:28 am
Division: Grad
State: NY
Has thanked: 0
Been thanked: 0

Re: Duration

Post by twototwenty »

For the past month or so, I have been working on a chinook design and after several failed attempts the best I have gotten is ten seconds-the thing doesnt even reach the ceiling of the classroom i am testing in.

The main problem, besides the fact that is is spectacularly heavy(which I am working on), is that the rotors do not rotate at exactly the same speed, causing it to flutter in uncontolled spirals until it hits the ground...
Does anyone have any suggestions as to how I can make the rotors rotate equally? States is in a week, and although we have a fallback, I am getting worried.

Return to “Helicopters C”