Boomilever B/C

Locked
Raleway
Exalted Member
Exalted Member
Posts: 228
Joined: March 12th, 2017, 7:19 pm
Division: C
Has thanked: 0
Been thanked: 1 time

Re: Boomilever B/C

Post by Raleway »

nambui0701 wrote:Hey guys :) I am a new member of SO and Boomilever event. May I ask if there is any mathematical / engineering approach to building the Boomilever instead of just blindly building and testing?

Much appreciate any answer.
I think balsaman would have loved to give the same exact answer like he did many times last and many seasons prior- run through old forums. All of the balsa events share the same design/physics/engineering concepts, just slightly modified based upon the design challenge. There are years worth of pages and information here ready to be dug up.

Side note: I will still be penning Len's name on my structures this year- I hope all those who have been helped by him will continue to do so. Wishing all the best to my fellow competitors and hope we can all learn from each other here!
Sleep is for the week; one only needs it once a week :!: :geek: :roll: :?: :idea:

God bless Len Joeris | Balsaman
User avatar
MadCow2357
Exalted Member
Exalted Member
Posts: 774
Joined: November 19th, 2017, 9:09 am
Division: C
State: RI
Has thanked: 211 times
Been thanked: 56 times
Contact:

Re: Boomilever B/C

Post by MadCow2357 »

I will do the same thing, Raleway. Len Joeris was beacon for all of us who did Balsa events :cry: . I will never forget the impact he made on my life.
MadCow2357's Userpage
Gallagher MS '19
Barrington HS '23
knightmoves
Member
Member
Posts: 594
Joined: April 26th, 2018, 6:40 pm
Has thanked: 4 times
Been thanked: 104 times

Re: Boomilever B/C

Post by knightmoves »

embokim wrote:Has anyone tried using dowels for tension members? Would they be inherently strong just because of the even and cylindrical design?
Why do you think being round would help you in tension over some other shape? Also think about how you're going to attach your dowels to the rest of your boomilever - I think you might find that easier if you had flat surfaces to join.
knightmoves
Member
Member
Posts: 594
Joined: April 26th, 2018, 6:40 pm
Has thanked: 4 times
Been thanked: 104 times

Re: Boomilever B/C

Post by knightmoves »

Sciencer101 wrote:So do you guys think that rule 4.i. will actually be followed, especially at regionals? Specifically the second part, "Teams will be given a choice of which testing apparatus they will use," could potentially be helpful at regionals.
I imagine one tester being out of plumb, everybody wants to use the other one, but the officials say no, big hassle.
This is a bit unrealistic, I know, but I was curious to what you guys think. :D
It would take a very large event to need two test stations on the go at once. You can schedule Boomilever tests every 7 minutes comfortably, so it's easy enough to accommodate 50 or 60 teams in a day. With two test stations and a joint B/C division regional, I'd use one test station for B and the other for C. So I don't see this rule coming in to play very often.

And you point out the problem with it - if an event does have two test stations, it's because it needs both stations in use to accommodate a large number of teams. In that case, having teams able to choose their test station might be problematic - if there's one obviously bad setup, everyone will choose the other and the scheduling breaks.
dholdgreve
Coach
Coach
Posts: 573
Joined: February 6th, 2006, 2:20 pm
Division: B
Has thanked: 0
Been thanked: 7 times

Re: Boomilever B/C

Post by dholdgreve »

It looks like we will be running Boom Div B at the Centerville Ohio Invitational on January 12th. I'd think this will be possibly the single largest Invitational in the country this year, with 60 teams competing in both B and C Div... Ya... 120 teams in total!

We will be using (1) SDU (Sand Dispensing Unit ;) ) with 1 as a back-up in case of catastrophic failure of the first one (It is older than any Div C Competitors!). Although each team is allotted 6 minutes to test, the reality is that many will fail within 3 minutes. There are 10 slots per time period, 6 time periods, so that works out to an allowance of 5 minutes per team, including slack time between tests to weigh the loads, and explain the process to the next group... super tight, but "doable."

In past competitions we have offered teams the option of hand loading if they so choose, and roughly 10% choose to do so. Due to the extremely tight schedule at Centerville, we will only be testing with a loader to keep things on schedule so no one misses their next event.. I hope you guys understand.

Regarding the loader, a couple things to consider:
Start slow to settle the bucket, the gradually increase to WIDE OPEN over a period of 10 to 20 seconds. A structure like this will likely only carry the load for a finite amount of time. Best to get as much in as you can!
The loader we use comes equipped with a supervisor shut-off, so when the structure breaks, the supervisor can pull the release and the gate valve snaps shut. Their reaction time is probably pretty consistent, so theoretically, running it wide open will get a slight bit more sand in the hopper than if you were running it half speed.
Hang the buck high enough to not touch the floor if the bucket tips a little, but not so high that it touches the dispensing tube
The bucket tipping a bit DOES NOT create an imbalanced load... unless you are using more than one point of connection (i.e. 2 chains from opposite sides of the bucket.)
Using the stabilization sticks to push the bucket back and forth in an effort to disperse the sand evenly within the bucket DOES CREATE an imbalanced load. Don't do this!
Try to keep the load as static as you can. Do this by keeping the chain perfectly vertical. The more the bucket moves,the more dynamic the load becomes.
ALWAYS check the chain before you start loading to make sure there are no kinks in the links. If there are, they are likely to pull out when you start loading. This will cause the load to suddenly drop the length of chain link and in all likelihood cause the boom to go... well... you know... BOOM!
ALWAYS look at your boom from the distal end before you start loading, and check to see if your mounting is centered, your boom is vertical, your loading block is horizontal, and centered on your compression beams. Once you start loading you can no longer adjust it!
If one of you is going to stabilize the bucket, I highly recommend to SIT cross legged in front of the bucket, not kneeling or sitting on one cheek (you know what I mean!) This is the most comfortable for the long haul. In any other position you will likely need to shift around, pushing the bucket to one side or the other.
Keep in mind that when you are using the loader, and you choose to dispense very slowly, there is no catch-up. The loader, run wide open, will dispense 15 KG of sand in about 3 minutes. I've seen a number of kids realize too late that they misjudged their time, and with 30 seconds to go, open it wide open, but still run out of time without getting all the sand in the bucket. Far better to get all the sand dispensed in half the time, than half the sand in all the time.
Finally, if you do not understand the process or what is about to happen, please ask! We are here to help, and truly do want to see each and every team succeed. Sometimes we can tell by that look that you have a question, or don't understand, but some of you guys are really good at hiding your total confusion! If you ever are unsure, please ask for a clarification. We will be glad to take whatever time is needed.
Dan Holdgreve
Northmont Science Olympiad

Dedicated to the Memory of Len Joeris
"For the betterment of Science"
User avatar
Cow481
Member
Member
Posts: 158
Joined: January 2nd, 2018, 6:18 pm
Division: B
State: PA
Has thanked: 0
Been thanked: 1 time

Re: Boomilever B/C

Post by Cow481 »

dholdgreve wrote:It looks like we will be running Boom Div B at the Centerville Ohio Invitational on January 12th. I'd think this will be possibly the single largest Invitational in the country this year, with 60 teams competing in both B and C Div... Ya... 120 teams in total!

We will be using (1) SDU (Sand Dispensing Unit ;) ) with 1 as a back-up in case of catastrophic failure of the first one (It is older than any Div C Competitors!). Although each team is allotted 6 minutes to test, the reality is that many will fail within 3 minutes. There are 10 slots per time period, 6 time periods, so that works out to an allowance of 5 minutes per team, including slack time between tests to weigh the loads, and explain the process to the next group... super tight, but "doable."

In past competitions we have offered teams the option of hand loading if they so choose, and roughly 10% choose to do so. Due to the extremely tight schedule at Centerville, we will only be testing with a loader to keep things on schedule so no one misses their next event.. I hope you guys understand.

Regarding the loader, a couple things to consider:
Start slow to settle the bucket, the gradually increase to WIDE OPEN over a period of 10 to 20 seconds. A structure like this will likely only carry the load for a finite amount of time. Best to get as much in as you can!
The loader we use comes equipped with a supervisor shut-off, so when the structure breaks, the supervisor can pull the release and the gate valve snaps shut. Their reaction time is probably pretty consistent, so theoretically, running it wide open will get a slight bit more sand in the hopper than if you were running it half speed.
Hang the buck high enough to not touch the floor if the bucket tips a little, but not so high that it touches the dispensing tube
The bucket tipping a bit DOES NOT create an imbalanced load... unless you are using more than one point of connection (i.e. 2 chains from opposite sides of the bucket.)
Using the stabilization sticks to push the bucket back and forth in an effort to disperse the sand evenly within the bucket DOES CREATE an imbalanced load. Don't do this!
Try to keep the load as static as you can. Do this by keeping the chain perfectly vertical. The more the bucket moves,the more dynamic the load becomes.
ALWAYS check the chain before you start loading to make sure there are no kinks in the links. If there are, they are likely to pull out when you start loading. This will cause the load to suddenly drop the length of chain link and in all likelihood cause the boom to go... well... you know... BOOM!
ALWAYS look at your boom from the distal end before you start loading, and check to see if your mounting is centered, your boom is vertical, your loading block is horizontal, and centered on your compression beams. Once you start loading you can no longer adjust it!
If one of you is going to stabilize the bucket, I highly recommend to SIT cross legged in front of the bucket, not kneeling or sitting on one cheek (you know what I mean!) This is the most comfortable for the long haul. In any other position you will likely need to shift around, pushing the bucket to one side or the other.
Keep in mind that when you are using the loader, and you choose to dispense very slowly, there is no catch-up. The loader, run wide open, will dispense 15 KG of sand in about 3 minutes. I've seen a number of kids realize too late that they misjudged their time, and with 30 seconds to go, open it wide open, but still run out of time without getting all the sand in the bucket. Far better to get all the sand dispensed in half the time, than half the sand in all the time.
Finally, if you do not understand the process or what is about to happen, please ask! We are here to help, and truly do want to see each and every team succeed. Sometimes we can tell by that look that you have a question, or don't understand, but some of you guys are really good at hiding your total confusion! If you ever are unsure, please ask for a clarification. We will be glad to take whatever time is needed.
This is really worth reading if you are new to the event and are going to your first tournament. I remember when I went to my first tournament, it was at wright state in 2017 and I was doing towers. I was so nervous about what to do and I was scared I was going to somehow mess it up that I actually asked my partner if he wanted to load instead of me. It eventually worked out fine and we got 26 which I would like to think is pretty good for my first tournament.
Medals
Invitationals: 9
Regionals: 5
States: 1
Nationals: 1

National Medals
2018: 5th in Towers
2019: Could have gotten top 3 in Boomilevers and Gliders if my team made it :cry:
User avatar
klastyioer
Member
Member
Posts: 429
Joined: April 22nd, 2018, 4:46 pm
Division: C
State: PA
Pronouns: She/Her/Hers
Has thanked: 2 times
Been thanked: 2 times
Contact:

Re: Boomilever B/C

Post by klastyioer »

Sciencer101 wrote:So do you guys think that rule 4.i. will actually be followed, especially at regionals? Specifically the second part, "Teams will be given a choice of which testing apparatus they will use," could potentially be helpful at regionals.
I imagine one tester being out of plumb, everybody wants to use the other one, but the officials say no, big hassle.
This is a bit unrealistic, I know, but I was curious to what you guys think. :D


- Sciencer
i feel like most comps only supply with automatic testing bases rather than manual and automatic
it's not about the medals; go out there and have fun. make progress, learn a few things and have one heck of a time; that's all that matters.

Check out Klastyioer's Userpage!
User avatar
klastyioer
Member
Member
Posts: 429
Joined: April 22nd, 2018, 4:46 pm
Division: C
State: PA
Pronouns: She/Her/Hers
Has thanked: 2 times
Been thanked: 2 times
Contact:

Re: Boomilever B/C

Post by klastyioer »

embokim wrote:Has anyone tried using dowels for tension members? Would they be inherently strong just because of the even and cylindrical design?

Thanks
in advance.
have not tried it, but if you have the time to and you also have a good enough design as a backup, go for it. it does sound like a heck of a lot of weight though. itd also be kinda hard to glue securely on. anything round is just difficult. you could always just sand it to scuff it up, but im not sure how much of an impact that would make.
it's not about the medals; go out there and have fun. make progress, learn a few things and have one heck of a time; that's all that matters.

Check out Klastyioer's Userpage!
Sciencer101
Member
Member
Posts: 16
Joined: September 5th, 2018, 6:58 am
Has thanked: 0
Been thanked: 0

Re: Boomilever B/C

Post by Sciencer101 »

What main compression members are you all using? I was thinking about 1/8 x 1/8, but that seems too thin.
Would 1/8 x 1/4 work? I am using light density balsa wood (about 7 lbs per ft^3)

- Sciencer
User avatar
MadCow2357
Exalted Member
Exalted Member
Posts: 774
Joined: November 19th, 2017, 9:09 am
Division: C
State: RI
Has thanked: 211 times
Been thanked: 56 times
Contact:

Re: Boomilever B/C

Post by MadCow2357 »

1/4" by 1/8", bout 2.5 grams per piece (I think). 1/8 by 1/8 is definitely too thin, and light balsa probably won't suffice.
MadCow2357's Userpage
Gallagher MS '19
Barrington HS '23
Locked

Return to “Boomilever B/C”

Who is online

Users browsing this forum: No registered users and 1 guest