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tobnpr
03-06-2012, 08:44 PM
Hi, first post...
My son is a mechanical engineering major at a Florida university. They have an annual competition (which I'll describe in a sec), and he asked me for advice because it revolves around boats...
Now, boats I know...owned a bunch up to 40'. But model boats- and control systems are a different animal, so I told him I'd try to pick the brains of those online...

In a nutshell, here's the deal....

The entire budget for the boat cannot exceed $80. This includes the value for any freebies, used parts, etc. No free rides here...NO pre-manufactured hulls- gotta be scratch built (no problem there, I'm a decent carpenter). He has used Parallax in bot projects, so this seemed a natural progression if we can make it work.

The boats will run an elliptical course, from a staged start. It looks like a half-dozen or more might be running in any given "heat". The course is the University fountain/reflecting pool. There will be a flexible, elliptical barrier set up, and the boats must run this course from right to left, around the barrier, and ending up at the finish line which is in-line (parallel) with the starting position.

The boats will each carry an orange for payload.

NO RADIO CONTROL, OR TETHERS permitted.

Here are my thoughts, so far...

It will be impossible to come up with any sort of gps autopilot system for this scale, and budget (I have a lot of experience with them in real boats).

A scratch built hull will be difficult to do because of the penetrations for shaft/rudder.

I'm thinking a Florida style Airboat- fan drive, with a controller board driving a servo to direct the fan thrust, as programmed.

One of my major concerns (and, no solution) is that because there are multiple boats running, a pre-programmed course/directives will go to ##*$& as soon as the hull is struck by another boat and pushed off course.

It is believed many boats are set up with sensors, pushed "left" until they detect the barrier, then just run along the barrier to the completion of the course.

We would greatly appreciate any advice- I'm sure there's a lot of intellect here, so please burn a few brain cells for us, and tell us what you think!

W9GFO
03-06-2012, 09:31 PM
You can hang the rudder off the stern to avoid any hull penetrations. A fan boat, if steered using air rudders is going to be squirrely, you would need a gyro I think to keep it going the intended direction. A keel and water rudder would help a lot.

If you want to use a standard boat prop, just make a stuffing box. The tiny bit it may leak during the competition should be insignificant. If you are really concerned, just make the stuffing box long enough that the inside opening is above the water line.

You could also make a catamaran with the motor suspended between the two hulls above the water. No worry of leakage then. The motor should be perfectly fine getting splashed (a common way to break in brushed motors is to run them for a while underwater) just be sure that it does not remain wet after the race.

How about a boat with a couple of wheels mounted on it that are meant to roll along the barrier?

Duane Degn
03-06-2012, 09:35 PM
It is believed many boats are set up with sensors, pushed "left" until they detect the barrier, then just run along the barrier to the completion of the course.


I don't see how you could come up with any other navigation method with all the other restrictions.

You can get ultrasound sensors from China for about $4. I'd think a pair of these might be able to keep a boat parallel to the barrier.

HobbyKing.com has lots of inexpensive servos.

Can the boats use external beacons? If you could have a couple of IR LEDs flashing, the boat might be able to use them to triangulate its position.

In case you don't know, Propellers (chips) cost a lot less than Basic Stamps and can do a lot more. I'm not sure if you'd be better off using a QuickStart board ($25) or making your own board with individual components.

Spiral_72
03-06-2012, 10:11 PM
Ultrasonics would be very troublesome depending on a lot of factors.

I too would stay away from airboats. Pontoons might not be bad, but a typical boat shape with a lot of volume in the water would be most predictable IMO.

( I'm going somewhere with this )

If you can float 10-15lbs of cement or?? it should be a lot more stable than a 8oz boat.

A compass would give handy information, though you'd need a ground reference with that to be of any use. With that in mind, how deep is the water and what does the bottom of the pool look like?? The reason I ask (and this might be a hair-brained idea) consider how an optical mouse works. It tracks movement depending on the direction and speed of it's optical feedback.... I'm sure you'd need a lens for the correct focal length, however if you gut a mouse and submerge the sensor off the bottom of the boat you'd be golden.... and a mouse will interface with a Prop which will make things so much easier.

So now with the mouse, you have ground reference, the compass gives you direction, after that it's a matter of programming with < $20 in sensors.

Sounds like it'd work don't it?

Duane Degn
03-06-2012, 10:45 PM
Ultrasonics would be very troublesome depending on a lot of factors.

Why do you think ultrasound would be a problem? I've been impressed with how well ultrasound works myself. The main problem I see is if other boats are also using ultrasound, you'd get interference from their sensors (and echos from the other sensors).


If you can float 10-15lbs of cement or??

The civil engineering department at my university participated in a canoe race each year. The canoes had to made out of cement.


So now with the mouse, you have ground reference, the compass gives you direction, after that it's a matter of programming with < $20 in sensors.


Parallax sells a mouse sensor kit (http://www.parallax.com/StoreSearchResults/tabid/768/List/0/SortField/4/ProductID/677/Default.aspx?txtSearch=mouse+sensor). It costs $25 which is a big chunk of $80. It should be possible to buy the sensor independent from the kit.

It might be possible to use Phil's B&W video capture (http://forums.parallax.com/showthread.php?135214-Propeller-Backpack-Capture-NTSC-Video)technique and use a cheap video camera (http://www.dealextreme.com/p/ntsc-mini-surveillance-av-camera-628x582px-6019)in the same way as an optical mouse sensor. The success of this approach might be very dependent on the surface characteristics of the ponds bottom.

Is the boat allowed to touch the barrier? Using wheeled touch sensors might be the easiest way to go if the boat can touch the barrier.

tobnpr
03-07-2012, 12:43 AM
Wow...thanks for all the interesting feedback. Interesting "brain twister", huh? Apparently there is no rule about going around the barrier, but my son has heard that the submarine attempts have failed...LOL...

Lots of good questions as well.

Optical reference- this would be able to "log" distance traveled by reading the bottom of the pool? INTERESTING....

Rather than try to answer all the questions- and I'm sure you guys will come up with more- I should have done this in the first place...here are the rules:

Great Navel Orange Race
2012 Competition Rules
Objective
The objective of the Great Navel Orange Race is to transfer an orange safely through a
required naval route in as little time as possible (maximum 5 minutes). The transfer device will
need to be loaded by an operator at the staging area and then have to traverse through the
course with the orange to the finish line. At the finish, another operator will need to remove
the orange from the vehicle and place the orange on the finishing bay.
Rules
The following rules outline the general guidelines that will be applied to the competition,
please note that any rule clarifications will be made by the course instructor and are final.
Course Layout
The figure below illustrates the basic course layout of the reflection pond during the
competition.
Course Description
Check In Area – This area is where your vessel will be inspected for any rules violations and
will be judged on your overall design and construction.
Staging Area – This is where your vessel will be placed into the reflection pond. There will
be separate starting gates, and your starting gate will be assigned, at random, after
check in.
Orange Bay – At the start of your race, your vessel will not have the orange already loaded;
when the race begins you will need to load your particular orange and start your vessel
around the track.
Reflection Pond – The course itself will require you to travel from the staging area to the
finishing area. There will be a flexible barrier preventing your vessel from traveling into
the area between the fountain and checkout area on the surface of the water (indicated
in orange on the figure, the barrier will be approximately 2 feet tall, will extend
approximately 6 inches into the water, and will be quite flexible, so plan accordingly),
however, it will not prevent waves or spray from traveling onto the track.
Finish – At the finish line, one of you teammates will remove the orange from your vessel,
place it on the final orange bay and your time will be recorded. At this point they should
remove the vessel from the water and proceed to the check out table. Note that your
vessel does not need to hit the finish wall at any particular point; it simply has to get
close enough for your operator to remove the orange. Also note that if your operator’s
body enters the water for any reason (arms are okay, stepping into the water is not),
you will automatically be disqualified and will receive the maximum time (5 minutes).
Check Out Area – This is where the final judging and score assignment will be completed.
Detailed Objective
At the start of the race, an operator from your team will need to pick up an orange from the
starting orange bay and load your vehicle. Once your transport vehicle has been loaded, it then
needs to travel the reflection pond and arrive at the finishing area. Once your vehicle has
reached the finishing line, a second operator will need to remove the orange from your vessel
and place it on the final orange bay. Your total time will be recorded as the time from when the
race is started until your unloading operator has placed your orange on the final orange bay.
Additional Rules
1. All oranges (standard navel oranges) will be provided by the instructor on the
competition day. Orange weight will be to pounds each.
2. The spending limit on the device will be $80.00.
3. You must bring all receipts of your purchased parts to the competition for your check in.
Online purchases will be allowed, however, you must still be able to provide a receipt of
your purchase. All parts used must be counted towards the allotted budget, and any
donated parts must have an equivalent RETAIL price associated with it (you must
provide proof of your retail price: store ad, online price search, etc.).
4. Your starting lane will be chosen at random. However, if your device makes it into the
final round you may choose your starting lane based respectively on the fastest times
recorded on the competition day.
5. All vessels must be self guided and self propelled, absolutely no remote control and no
string or line-based guidance systems will be allowed.
6. The entire fountain will be allowed for travel, i.e. although the barrier is in place
(indicated in orange on figure) its purpose is to prevent you from traveling into this
middle region on the water’s surface.
7. The team must perform all production of the device themselves (no commercial
manufacturing). No preassembled parts or kits will be allowed (this includes store
purchased boats and boat hulls).
8. Your vehicle must be based in the water, i.e., it cannot leave the water area at any point
during the race.
9. Your vehicle must remain connected at all times during the race and cannot leave any
excess vehicle remnants or parts behind.
10. If your device has a launching mechanism, only one launch will be permitted during each
run. In this case, your device cannot be manually launched. Your design must include a
timed ignition that can be switched on at the start of the run after your device is loaded
with the orange.
11. The orange bay will be within reaching distance of the staging area. At the start of the
race one of your team members must pick up their respective orange from the orange
bay and secure it in your vessel. Your loading and unloading time will be included in your
total race time, so make sure you account for loading and unloading the orange in your
design.
12. The orange cannot be loaded in your device before the start of the timed run.
13. No objects or devices (i.e., nets, poles, etc) will be allowed to retrieve your vehicle or
orange from water. The orange must be retrieved and unloaded by a group member at
the finish line.
14. The same group member will NOT be allowed to load (start line) and unload (finish line)
the orange during the competition. This is for safety and to prevent running through the
designated competition areas.
15. Your vehicle must transport one, and only one orange to the finish line; if your vehicle
looses the orange during the race a penalty will be assessed to your performance score.
16. The orange must remain in its original condition during the race; if the orange does not
return in its original condition, a penalty will be assessed to your performance score.
17. No liquid flammable objects are allowed (including gasoline and other liquid
combustible fuels).
18. Solid fuel rockets are allowed; however, if your design is deemed unsafe at check-in, you
will not be allowed to race and will receive the maximum time (5 minutes).
19. No animals of any kind are allowed.
20. The fountain will be on, and in its normal operating conditions during the competition.
21. All designs must be capable of finishing, at most, 4 trials.
22. If each run uses disposable items (i.e. CO2 cartridges, etc), then the cost must be
calculated on ALL 4 trials.
23. Cost of materials must include tax.
24. A list of ALL materials used must be submitted on competition day with receipts.
25. Once the race has begun, no interference will be allowed (with the exception of Rule 21)
by any of your team members. If your vessel fails to finish the race, the maximum
finishing time of 5 minutes will be given to you.
26. If at any point any of your operators enters the water or enters the competition
boundaries, your group will be disqualified and given the maximum finishing time of 5
minutes.
27. If, during the race, your vessel gets stuck on the outside of the track, a team member
may remove the vessel from the water (assuming they can reach it without entering the
water themselves) and return to the starting area to restart the vessel. Note that the
time will not restart, and you must wait 45 seconds before restarting your vessel for the
first time. Also, upon restart you may place your vessel at any of the starting bays (does
not have to be the one that you were assigned).
28. Each team must check out properly by:
a) Turning in their competition sheet.
b) Turning in their final report.
c) Returning the orange to the starting orange bay.
d) Disposing of any waste in relation to the device.
e) Turning in your peer evaluations (individual responsibility).
f) Failure to complete the above tasks will result in a 50% loss of the team’s overall
performance score.
29. Additional rules and clarifications will be posted on WebCT.
Scoring
Final competition grades will consist of six categories (total of 1000 points):
Extended Abstract (150 points)
Pre-competition Evaluation (200 points)
Performance (150 points)
Accuracy (100 points)
Ranking (50 points)
Typed Competition Form (50 Points)
Final Report (300 points)
And any deductions that the team receives.
Once a team receives a point total (i.e. 935 points), each team member will have that score
multiplied by his/her peer evaluation score (out of 100%). Evaluation will occur as follows:
Extended Abstract (200 points)
Please refer to the extended abstract detail handout for guidelines in writing your abstract,
and the technical content that it must contain.
Pre-Competition Evaluation (200 points)
This category is worth a possible 200 points and is divided into five sections. You will receive a
maximum of 40 points for each subcategory.
1. Creativity – Based on the individuality of the device, as judged by the check-in judges.
2. Professionalism – Based on the overall quality of the device and behavior of the team
during the competition.
3. Operational Soundness – This is based on your vehicle’s overall functionality and
repeatability, and that the vehicle’s design is fundamentally safe.
4. Design Specifications – This category will gauge your vehicle’s compliance with the
nonperformance
5. Receipts and Materials List – A list of all materials used must be submitted on
competition day along with receipts to assure compliance with the spending limit as
outlined in the rules. Both of the aforementioned items should be attached to the
competition form.
Performance Score (150 Points)
This category is worth a possible 150 points. Teams will receive points based on the formula
shown below, where t is the amount of time that it takes to transport the orange across the
finish line, in seconds.
P(t) = 220 - 0.325 t
For example, if a team’s transport performs the task in 1 minute and 34 seconds, that team
would receive a performance score of:
P(94s) = 220 - 0.32594 =189.45
If your vehicle looses the orange during the course of the race, or does not return the
orange in its original condition, you will receive a mandatory penalty to your score. This penalty
will result in you receiving half of your final performance score.
Accuracy Score (100 Points)
This category is worth a possible 100 points. Teams will receive points based on the formula
shown below, where t is the amount of time that it takes to transport the orange across the
finish line, in seconds, and c is the predicted finishing time that your team calculated.
A(t,c) = 100 - 0.5 (t - c - 30)
For example, if the team in the preceding example predicted that their vehicle would complete
the task in 2 minutes and 14 seconds, then the team would receive an accuracy score of:
A(94s,134s) =100 - 0.5 (94 -134 - 30)= 95
Ranking Score (50 points)
After the competition, the performance scores of all teams will be ranked and points for this
category will be assigned based on your position within these rankings. Your score will be
equivalent to the percentile that you are located within these rankings. For example, if you get
the best performance score, you will receive the total 50 points, if you get the worst
performance score, you will receive 0 points. If you are better than 60% of the teams you will
receive 60% of the possible 50 points (30 points).
Competition Form (50 Points)
The competition form must be typed and presented to the check in station before your
designated heat time in order to get full credit. Failure to type your form will result in a loss of
50 points.
Final Report (300 Points)
Please read the final report detail handout for the guidelines for writing your final report.
Your final report will be due on the day of the competition and will need to be turned in when
you check out after your heat time.
Final Competition Grades and Peer Evaluations
When you combine the scores from all of the scoring categories you will receive a score out
of a total possible 1000 points. This is not what you will receive as an individual grade. Your
grade will take into account a peer evaluation. Each member in your group must fill out a peer
evaluation, which is located online, in the same area that this document was posted. Be sure to
download it, fill it out, and submit it along with your copy of the technical paper. If you don’t do
a peer evaluation, you will receive a 100 point deduction. Team members will “grade” each
other on the following:
1. Attendance – You will grade your teammates’ attendance on a scale of 0-10 where 10
should be awarded if that member attended all meetings and a 0 should be awarded if
that member attended no meetings.
2. Reports Contribution – You will grade your teammates’ contribution to the group
reports on a scale of 0-10 where 10 should be awarded if that member contributed their
fair share to the reports produced by the team.
3. Intellectual Contribution – You will grade your teammates’ mental contribution on a
scale of 0-10 where 10 should be awarded if that member contributed their fair share to
the design and other intellectual aspects of your project.
4. Physical Contribution – You will grade your teammates’ physical contribution on a scale
of 0-10 where a 10 should be awarded if that member contributed their fair share to
building your design and other physical aspects of your project.
Your peer evaluation score is computed by adding all of your peer evaluations together and
dividing by the total amount. For example, if you receive a 20/40 from teammate 1, a 30/40
from teammate 2, a 40/40 from teammate 3, and an overall raw score of 950 from your reports
and competition performance, your peer evaluation will be (20+30+40) / (40+40+40) = 90/120 =
0.75, and your score final score will be 0.75 * 950 = 712.50. It is possible to get a final score of 0
if a member does not participate in the design and fabrication of the vehicle and/or the writing
of the report.
Peer Evaluations can dramatically change a person’s grade, so please be fair when you’re
evaluating your teammates. This system is used to ensure teamwork and fairness among
teammates. If you feel that you’ve been treated unfairly in your group, please talk to your
teaching assistant or the course coordinator. These people will act as arbiters and can assist in
situations of unfair peer evaluations.
Competition Day Schedule
Before you arrive at the reflection pond, make sure you fill out your team’s competition
form and bring it to the check-in area during your designated check-in period. Remember, all
team information, predicted time, and group member’s names must be TYPED onto the
competition form (failure to do so will result in a loss of 50 points). When you arrive on
competition day, you should first go to the check-in area and register your team for the
competition. All participating group members must be present 15 minutes prior to their
allotted start time, and must be available up to 30 minutes after their allotted start time. Make
sure you bring your competition form and transport device to the competition; also ensure that
all receipts are stapled to your competition form before checking in. At the check-in table, your
device will be inspected and the pre-competition evaluation will be completed. After check in,
you will be directed to a race lane where you will have one minute to prepare the device for the
race. After the race has finished, at least one member of your group must take your
competition form with your official race time to the check-out area where your final score will
be assessed.
Once the race is over make sure you have cleaned any debris made from your device and
collect any of your team’s parts from the fountain. Any team that does not completely clean up
will have 100 points deducted from their final competition score as well as their final grade.
This is equivalent to one whole letter grade.
At the check out table, turn in your completed competition form, your final written report
and your peer evaluation forms (individually sealed with lab section number, lab instructor and
team number located on the envelope).
GOOD LUCK!!!

idbruce
03-07-2012, 01:12 AM
@tobpnr

Could you please post the illustration for the course layout?

Bruce

Spiral_72
03-07-2012, 01:23 AM
Why do you think ultrasound would be a problem? I've been impressed with how well ultrasound works myself. The main problem I see is if other boats are also using ultrasound, you'd get interference from their sensors (and echos from the other sensors).

Sorry Duane. I shouldn't make a statement like that without explaining. My thoughts were, you would have other ships passing or being passed, you could be run into and spin your boat around and all the while rocking from the waves.

I was thinking about using an old serial mouse from the Goodwill. The output stream is data, direction, speed and buttons (though I've forgotten the exact details). Heck I guess you could use the buttons for collision detection too :)



P.S.
I dunno where the mouse idea come from. I don't remember seeing anyone that used it. I bet that'd make an awesome wheel encoder alternative for my rolling bot!!! Too bad I gutted all my old serial mouse-es for the limit switches and cables :(

EDIT:
Now that I consider it, I remember an article where they used the guts from an optical mouse to make a monochrome scanner. Why I dunno, but I think the sensor was actually an imaging sensor of maybe 8x8 or 16x16 pixels. It was very low resolution but it works perfectly for what it does.... track moving details on a surface.

mindrobots
03-07-2012, 01:34 AM
Paddle boat. Not a stern wheeler but side wheels. Provides differential (sorry, Gordon) steering. A shallow draft with a flat wide bottom would give you stability and not hinder turning. You really don't need much draft and just in case there is wind on race day, drop a centerboard down the middle to eliminated to eliminate any drift due to wind.

Power the wheels with a pair of CR servos and it would be just like a robot. Add a couple ultrasound sensors and you're good to go.

tobnpr
03-07-2012, 01:54 AM
Bruce, I finally figured out that I could take a screenshot with my phone and upload it to Photobucket for the course layout.

I'm really wondering whether...
Speed would be king. Get out in front quickly, so there's less chance of being interfered with by other vessels.
Displacement would be king. AKA the concrete boat comment... same idea, less chance of getting knocked off-course...but with displacement comes more power ($$), or much slower speeds- which wouldn't cut it.

Here is the course layout:

http://i211.photobucket.com/albums/bb294/tobnpr/IMAG0668.jpg

jmg
03-07-2012, 04:10 AM
["5. All vessels must be self guided and self propelled, absolutely no remote control and no
string or line-based guidance systems will be allowed."]

So that is not quite the same as #1, and excludes Infrared, but it does not exclude GPS.
However, given the simplicity of the course, inertial guidance may be enough.

Or, there are optical distance sensors, that work by triangulation. You would need to check how they interact.
Wall-hugging would create a boat-jam, but a looping bounce algorithm should 'go round' anyone wall following.

I like this rule ...

["Once the race is over make sure you have cleaned any debris made from your device and
collect any of your team’s parts from the fountain. Any team that does not completely clean up
will have 100 points deducted from their final competition score as well as their final grade."]

What Debris ?! { If one boat wrecks another, whose debris is that? }

A boat that 'somehow by accident' generated considerable side-wash and thrust, would have an advantage here.
Of course, you will not be the only one to see that, so need to design to tolerate

added :
["4. Your starting lane will be chosen at random. However, if your device makes it into the
final round you may choose your starting lane based respectively on the fastest times
recorded on the competition day."]

That's tough, as the outside lanes have a clear advantage, and need almost no control intelligence.

Perhaps a microswitch on the orange holder, could tell the program which lane you are in ?

A LOW centre of gravity, to the point of mostly submerged, and a wedge front would 'barge past' other entries.

jmg
03-07-2012, 04:18 AM
Scoring is a little skewed ?? : You only get 150 out of 1000 for actually working.

Someone can build an empty shell, and get 100% on the accuracy (they KNOW with great precision, how long it will take!),
and focus on the remaining 750 points. Marketing could easily trump engineering here.

W9GFO
03-07-2012, 04:37 AM
Since the course is an arc, you could design a very long boat that moves only in an arc. Taken to the extreme, make a boat several feet long with a rudder that is adjustable for each lane. No sensors or controller required. Just a battery and a couple of switches.

jmg
03-07-2012, 04:41 AM
It is believed many boats are set up with sensors, pushed "left" until they detect the barrier, then just run along the barrier to the completion of the course.


Just to clarify, could they also choose the outer edge ? (the fountain edge is not mentioned ?) - but if everyone is going shortest, more speed may be possible on the longer course ?

jmg
03-07-2012, 04:45 AM
Since the course is an arc, you could design a very long boat that moves only in an arc. Taken to the extreme, make a boat several feet long with a rudder that is adjustable for each lane. No sensors or controller required. Just a battery and a couple of switches.

Hehe - Or, a boat the length of the course, with an inclined tube the orange simply rolls down... ;)
no need for motor, battery or switches...

tobnpr
03-08-2012, 05:39 PM
Scoring is a little skewed ?? : You only get 150 out of 1000 for actually working.

Someone can build an empty shell, and get 100% on the accuracy (they KNOW with great precision, how long it will take!),
and focus on the remaining 750 points. Marketing could easily trump engineering here.

Yup, I was going over that with my son...I don't know what the requirements of the written abstract are, but now I'm thinking...that we've been overthinking...this.

I checked on YouTube, and sure enough, there are some vids, one of the winning boat. It just hauls *** around the outer perimeter of the fountain, hugging the wall, while other entries are slow, and cumbersome. Since it's a time competition, and not about navigating the shortest possible course, I'm thinking that concept is the best. Very light , stable, hull design to skate across the water- i like the catamaran idea with the engine/prop centered between the hulls. Maybe just set the prop for a very slight left turn based on the lane assigned (?), and let her rip...

This looks like a block of styrofoam, just ripping across the surface of the water!

http://www.youtube.com/watch?v=FKUu5uEa3yQ


a (http://www.youtube.com/watch?v=FKUu5uEa3yQ)nd another one, along the lines of what I was thinking...

http://www.youtube.com/watch?v=Qzzy81DCf2Y&feature=related

kwinn
03-09-2012, 02:56 AM
A can of insulating spray foam, a simple mold (plaster of paris) an AA battery pack, 2 dc motors, and 2 counter rotating propellers

Duane Degn
03-09-2012, 03:23 AM
Didn't the rules say solid rocket engine were allowed? That might be the fastest and cheapest alternative. If you can keep the boat on the water.

kwinn
03-09-2012, 03:49 AM
Ok, ok Duane, a little concrete, a simple mold (plaster of paris) and 2 rocket engines. How do you stop it to remove the orange? Oh and better add a seat belt for the orange.