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Thampson WR-car record

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Thampson WR-car record

Post by RaZias » Sun Oct 17, 2010 3:45 pm

I think it´s time to consider Thampson WR-car distance an WR-record for the score board, at least an unofficial record.

At some time WRA2 forum has the Alex Fischer score annonced, why not the Thampson record also ? AG

If I am going to make a record surely will be a ground speed record, it doesn´t demand a very long road and it will be cool to see how fast these things can go 8)


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Re: Thampson WR-car record

Post by WRA2 » Sun Oct 17, 2010 4:16 pm

RaZias wrote:I think it´s time to consider Thampson WR-car distance an WR-record for the score board, at least an unofficial record.

At some time WRA2 forum has the Alex Fischer score annonced, why not the Thampson record also ? AG

If I am going to make a record surely will be a ground speed record, it doesn´t demand a very long road and it will be cool to see how fast these things can go 8)
AG That is a super idea! We have been planning on having a water rocket car class for a while now. What we will need to get this started is to come to a consensus on what the rules will be. For now we will start with one class and that will be a distance class (we can decide about a speed competition at a later date). What we need now is for the water rocket car experts who are members to make suggestions (using this thread). Once we have a set of rules we can recognize Todd's distance as a record. (other members are also welcome to offer ideas too).

Todd, What parameters did you build your car to?

Should we require cameras carried onboard, ground video (from external cameras), 2 runs in opposite directions, What weight limit (if any since these don't fly we don't have to worry about weight), construction materials? (separate for chassis and pressure vessel). Launcher specifications?

We will also need someone to come up with a catchy name for the class too SC:


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Re: Thampson WR-car record

Post by RaZias » Sun Oct 17, 2010 4:51 pm

A nice rule is no metalic parts reinforcing the rocket or inside it (like the metalic copling...altough hard plastic pieces of coplig when fired can be also dangerous).

That way if the bottle burts wont eject any metal pieces.

---Rule 1

No metalic pieces inside the rocket.
No metalic reinforcement around the bottle.

---Rule 3

The only propulsion accepted must came from the water and air from the bottle.
The wheels can´t have no propulsion system.

---Rule 4

The launcher can´t offer propulsion.
But a vertical square can be added behind the quick release to offer a pression point for the water jet (I don´t knw if this has any effect)

---Rule 5

Wind speed should be measured.
(Does this make any difference ?)

---Rule 6

The floor type must be categorized.
(How the hell I do that ?)

---Rule 7

Someone should make a rule to avoid launching WR-cars in a active road.
I know that sometimes is the only place but some restrictions must be tought.

---Rule 8

There must be a rule to avoid a creation of a Stomp-rocket.
I know that there is already a limit imposed for WR, but what about WR-cars ?


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Re: Thampson WR-car record

Post by WRA2 » Sun Oct 17, 2010 8:03 pm

RaZias wrote:A nice rule is no metalic parts reinforcing the rocket or inside it (like the metalic copling...altough hard plastic pieces of coplig when fired can be also dangerous).

That way if the bottle burts wont eject any metal pieces.

---Rule 1

No metalic pieces inside the rocket.
No metalic reinforcement around the bottle.
I agree with no metal used for the pressure vessel. This would include nozzles, couplings and the method to attach the pressure vessel to the vehicle. Metal parts would be acceptable to use on the rest of the vehicle.

RaZias wrote: ---Rule 3

The only propulsion accepted must came from the water and air from the bottle.
The wheels can´t have no propulsion system.
I agree. AG
RaZias wrote: ---Rule 4

The launcher can´t offer propulsion.
But a vertical square can be added behind the quick release to offer a pression point for the water jet (I don´t knw if this has any effect)
I agree AG
RaZias wrote: ---Rule 5

Wind speed should be measured.
(Does this make any difference ?)
Having two runs averaged running in opposite directions similar to land speed record competitions would remove the wind as a variable.
RaZias wrote: ---Rule 6

The floor type must be categorized.
(How the hell I do that ?)
I think that the surface type would be too difficult to enforce but should be mentioned in any submission. A way we could level the playing field is to require that all attempts be made outside. That would eliminate the advantage that someone could have if they had access to a large warehouse with a perfectly smooth floor and no wind.
RaZias wrote: ---Rule 7

Someone should make a rule to avoid launching WR-cars in a active road.
I know that sometimes is the only place but some restrictions must be tought.
That would be needed on the "safety rules" section. We will have to add a water rocket car section to the water rocket safety rules.
RaZias wrote: ---Rule 8

There must be a rule to avoid a creation of a Stomp-rocket.
I know that there is already a limit imposed for WR, but what about WR-cars ?
I agree AG stomp rockets have no place in the competition. A lot of our rules that we already have for rockets to avoid stomp rockets could apply.


What about steering? Is steering optional or required? What about the method of measurement? How do we record the measurement? Using the ground camera? Markings on the track that are visible from an onboard camera?


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Re: Thampson WR-car record

Post by RaZias » Mon Oct 18, 2010 6:41 am

---- The wind

I think the Wind-variable should be study.
Between 2 launches it´s true that wind can change but if you live in a very windy area you can take advantage of that because there is always a strong wind

Just take a look in the North area of the Atlantic coast of France, always strong winds.

Anyway that is something that won´t matter for the moment.

---- the distance

For measurement of distance I think a distance can be measured by the Google Tool in the maps as Thampson did.

The reference spots for the measurement should be present during the movie filmed by a side (or front) camera in the rocket.

For exemple if it filmed a certain house or park that would be a reference spot to be marked in Google maps.

Obviously the resoultion of the Google Maps would be the resolution accepted.

For exemple if a car makes more 10 meters than the other and Google Maps as (I don´t know) a 15 meters resolution then the new record won´t be accepted because is not able to be verified.

---- The steering

I think it´s up to the person to use steering or not, the important is to make the distance.
Not everyone has a budget for a electric steering, but they have surely for a aerodinamic steering.
Even small springs could be used as a correction system.

This would open a door to endless possibilities, and that is the fun of WR.


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Re: Thampson WR-car record

Post by WRA2 » Mon Oct 18, 2010 4:46 pm

RaZias wrote:---- The wind

I think the Wind-variable should be study.
Between 2 launches it´s true that wind can change but if you live in a very windy area you can take advantage of that because there is always a strong wind

Just take a look in the North area of the Atlantic coast of France, always strong winds.

Anyway that is something that won´t matter for the moment.
I think it would be too difficult to enforce measuring the wind. What we did for the rocket competitions is require that two flights occur within a 2 hour time period. This prevents people from waiting for "perfect conditions" for both flights. The competitor has to fly that second flight within two hours or the record attempt would not comply. We could do the same thing for the cars and require two runs in opposite directions within 2 hours. That would be fair for everyone.

As far as some locations being windier then others I do not have a solution. People living in warmer climates always will have advantages with weather and no one has come up with a way to level that yet. We see the same issues with the rocket competitions where people in warm climates can launch year round enabling more testing, developing and launch time while others have to deal with sub-freezing temperatures, deep snow etc.
RaZias wrote:---- the distance

For measurement of distance I think a distance can be measured by the Google Tool in the maps as Thampson did.

The reference spots for the measurement should be present during the movie filmed by a side (or front) camera in the rocket.

For exemple if it filmed a certain house or park that would be a reference spot to be marked in Google maps.

Obviously the resoultion of the Google Maps would be the resolution accepted.

For exemple if a car makes more 10 meters than the other and Google Maps as (I don´t know) a 15 meters resolution then the new record won´t be accepted because is not able to be verified.
Good suggestions on using Google earth but there must be a better way. What about those electronic measurement devices I have seen construction workers use to measure when building houses. Maybe there are low cost versions that would be more accurate then Google earth.

RaZias wrote:---- The steering

I think it´s up to the person to use steering or not, the important is to make the distance.
Not everyone has a budget for a electric steering, but they have surely for a aerodinamic steering.
Even small springs could be used as a correction system.

This would open a door to endless possibilities, and that is the fun of WR.
Maybe steering isn't really the issue. What about the "track" that will be used, How wide?? What would be a legal run? How much "off course" would be considered acceptable. Does the car need to run in an intended direction to count. What if the car makes a 90 degree turn during the run. My take is that the run should be as straight as possible and that anything more then a few degrees off the launched direction would make that run ineligible.


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Re: Thampson WR-car record

Post by RaZias » Tue Oct 19, 2010 1:42 pm

Only more testing can say what straightness would be possible to achive without expensive systems like electronics so that way we won´t demand a impossible straightness.

About the distance measurement I have a lack of ideas, I don´t understand what device you are talking about from the house builders.

Is the one that uses a tripod for measuring streets ?
Isn´t that expensive ?


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Re: Thampson WR-car record

Post by WRA2 » Tue Oct 19, 2010 8:39 pm

RaZias wrote:Only more testing can say what straightness would be possible to achive without expensive systems like electronics so that way we won´t demand a impossible straightness.

About the distance measurement I have a lack of ideas, I don´t understand what device you are talking about from the house builders.

Is the one that uses a tripod for measuring streets ?
Isn´t that expensive ?
I think that the lowest cost method would be to have the competitor mark the course using a tape measure in 10 foot/10 meter divisions (competitor can use local measurement units) and use the tape measure to measure the distance from the last marker passed to the stopped car. It could be displayed via video to show the distance traveled.

PH:


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Re: Thampson WR-car record

Post by FredK » Wed Oct 20, 2010 4:05 pm

What about having someone not connected to the team do the measurement and send a signed statement that the measurement is true?


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Re: Thampson WR-car record

Post by WRA2 » Wed Oct 20, 2010 7:13 pm

FredK wrote:What about having someone not connected to the team do the measurement and send a signed statement that the measurement is true?
I think that having the competitor record the measurement process with a video camera will be good enough. This has come up in the past and the answer is that it does not work. Requiring people to get witnesses and have them sign sworn statements would discourage many people from competing as most people would not want to be bothered to fill out a lot of paperwork or have their name published on the web. There is also the possibility that the person is actually connected to the team in some way. If someone was planning on cheating, they would cheat this portion too by having a "friend" vouch for them. With the great distances involved because we are a worldwide association, having the association leaders review every record attempt in person is also not practical especially since we require no dues or membership fees and wish to keep it that way. By submitting video evidence we can have all the teams validate the measurements. With 500 sets of eyes reviewing the record submission any cheating should be spotted. Say someone tried to claim a water rocket record and the rocket looked far too large to comply with the 1500 gram maximum, someone would notice it and bring it to our attention, We would then require that the competitor submit a photo of the rocket in question on a digital scale so everyone could make the judgment if it meets the requirements.


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Re: Thampson WR-car record

Post by Spaceman Spiff » Thu Oct 21, 2010 10:33 pm

Here's my input on the rules:

There should be two "runs" of the Water Rocket Car. They should be some reasonable time period apart. I say we use 2 hours so it is the same time limit as for Water Rocket Flights. This works great for Water Rockets and keeps people from taking advantage of weather conditions, and everyone agrees that it's a good idea.

The reason I want two "runs" is one step beyond the above: I want to make each "run" on the same course each time, but 180 degrees in the opposite direction on the decond "run". Then the two distances are averaged to get the final number. The reason I suggest this is that the rule makes sure that there are no hills or terrain helping the car. By going the reverse direction, going downhill one way is going uphill the other. This is also similar to the approved Water Rocket two flight altimeter average.

I think we also need to say something about the car being in contact with the ground the entire time. Otherwise, some wiseguy will put some tiny wheels on a Water Rocket and launch it at an angle upwards and go hundreds of feet. We have to insist the wheels are rolling on the ground.

How do those ideas sound?


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Re: Thampson WR-car record

Post by RaZias » Fri Oct 22, 2010 11:28 am

I think the ideas sound ok.

It´s just a matter of time and will to Thampson do this and get a world record.


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Re: Thampson WR-car record

Post by thampson » Sat Oct 23, 2010 8:42 am

Hi all, I haven't checked the forum for a coupe of weeks, so here is my input to this discussion.

> Todd, What parameters did you build your car to?
I dont know if I initially built it to any particular specification. Our main goals were safety, stability then distance. From a safety perspective, we always had multiple points where the pressure vessels were tethered to the chassis, usually 2 separate points per bottle. The chassis had one point (a riser between the bottles) where the bottles exert force on the chassis, this also enables the bottles to be held in place and not separate from the chassis (assisted by the bottle tethers). Our launcher has always had an abort and a rope activated quick release so it can be launched from a distance. We have always had 4 wheels, may want to limit this as the minimum.

>Camera
We have only recently added the camera but I think for record purposes onboard camera is a must, realistically they are very cheap these days, so this isnt cost prohibitive. Ground video is also good to show the start location and where it ends up, again most people have a video camera of some description that can be used for this purpose.

>Weight Limit
I dont know if an upper weight limit is necessary as it usually only slows the car down and it will help the cars stability and not let it off the ground. On the other hand a minimum weight limit may be required as the very light cars have a tendency to get airborne and flip which can be dangerous. However once a car flips or gets airborne it wouldn't qualify as a car so it couldn't break the record.

> 2 runs in opposite direction
I think this is a must, averaging the runs within a time limit ie: 2hrs, will ensure that any slope doesnt unfairly add to the distance or speed. Also it way be worth limiting the difference between the 2 runs to no more than 25%. So for example if one run was 400m down a hill and the second was only 10m back the other way, the average is 205m which is obviously an unfair method of taking a record. So with the 25% rule, if the first run was 10m and the second was more than 14m, then it would be more than 25% difference and the second run would either not count or would only be allowed to be 14m as a maximum.

> Metal Parts
Couplings - I think for this class that this may need more debate. We use aluminium robinson coupling which weigh in at about 10grams. Other plastic tornado type coupling weigh around the same ~8 - 13g. So whether its metal or plastic in the case of an explosion and seperating from the car the plastic and metal parts will still impart the same force if they hit someone. In an explosion the couping always stay attached to parts of the bottle, ie: its usually the bottle that rips/tears starting the explosion, its then a matter of containing the pieces. With water rockets cars we have an advantage over the vertical rockets in that we have a chassis to tether the bottles to. In our car design we have the 2 points per bottle as well as the riser to ensure the bottles doesnt separate from the chassis and fly off. To provide additional safety we have been working on a robinson coupling kevlar tether which tethers each of the actual couplings to the chassis, similar to the way F1 cars tether the wheels to the chassis so they no longer separate from the car in a crash. I believe this is a safer alternative than just mandating non metal parts whilst not mandating tethers. If a tether is mandated then there is no difference whether the coupling is metal or plastic.

> Wind Speed should be measured
I dont think its relevant to adding to distance substantially, the run in the reverse direction would even out any gains anyway. We have launched the car in 50kmh wind and it really didnt make a noticeable difference to distance or speed.

> The Floor type must be categorized
I wasnt sureif you were referring to the floor of the car ie: chassis or the road surface.
If its the floor of the car - I think this should be left open to allow for different designs. As long as the chassis provides sufficient locations to tether the bottles it shouldn't matter its construction. If 2 tethers per bottle is mandated then the chassis design will need to conform to that rule.

If its the road surface then outdoor would stop inside smooth concrete etc as suggested, but maybe a class on grass might be an option, going 100m on grass is a lot more difficult than doing in on tarmac, also no vehicles to annoy you on the grass (although people may be an issue). Maybe a tarmac class and a grass class, possibly a snow/ice class as well ?

> Launching on an active road
Realistically you are going to need to launch on a road if you want to find 150m of straight tarmac. We have tried car parks (too many damn concrete blocks), driveways (not long enough any more) so you can find places to test that are not on a road as such. Although there are plenty of cul-de-sac, dead end roads, industrial areas that can be found on the weekend with little or no traffic. You need to be sensible about where you launch and personnel safety. Most people that do come past us when we are launching are interested and slow down and sometimes stop just to take a look and see what it is we are up to :)

> Stomp rockets
I dont have any issues with stomp rockets being banned from this competition.

> Steering
This should be left to the designer as to whether they want active (r/c) or passive (fins) steering. Experience tells me that if you seriously want to go after a distance record you are going to need to steer it. R/C Steering is the obvious solution and really not that difficult to build. I had never done r/c before trying it on our car, so if you can build a rocket car to challenge a record its well within your abilities to build the r/c steering for it as well.

The only method of steering which should not be allowed is attaching the car to a tensioned string/rope and letting it run along the string to keep it straight.

> Method of measurement
The simplest and cheapest is marks on the ground. Take a tape measure and mark every 10m. Although its a good verification to check with google earth, which is pretty accurate. As long as you have a reference point, ie: driveway, bend in the road, gutter grate etc which is visible from google earth as the starting location. If the ground marks + google earth are a close match then this would suffice. When we were going distances of 30-45 m the google earth errors were noticeable, but now that we are around 150m google earth is very accurate as a method of confirming distance.

> Vehicle Track
The width of the car between the wheels (track) is one element of the design which can effect stability. Overcoming thrust steering is the difficult part of which a wider track helps but by no means would it cancel it out. Although making a car 1m long with a track of 3m probably wouldnt be in the spirit of the competition. Perhaps limiting the track width to no more than twice the length of the car may be worth considering.

> How much off course would be considered acceptable
The more you go off course the less the distance is anyway so I would think we should accept cars not going perfectly straight. However when it comes to measuring the run, the measurement needs to be in a straight line from the starting location to the finish location, ie: you dont count the off course metres. Alternatively when the 10m marks are layed out on the road/ground, you can nominate a centreline (ie: you intended direction), then when the car comes to rest the measurement is done along the centreline to a distance no further then where the car comes to rest, ie: you only measure that vector of the distance so all off course metres traveled are not counted.

> Does a car need to run in an intended direction to count
Generally to meet the 2 runs in the opposite direction, cancel the hills and wind assistance you would need to do the runs 180 degrees apart, maybe along the intended centreline as above.

> What if the car makes a 90 degree turn along the run
Its probably going to hit something .. like a gutter .. LOL ... :) ... seriously though, if we use the centreline ,measuring method above any turns along the course just loose potential distance, so there is no advantage in designing a car that snap turns along the run.

> More then a few degrees off the launched direction would make that run ineligible
Getting a car to go straight is very difficult .. a lot harder than it looks ... if we only allow a few degrees we are not going to get anyone setting any records .. :) I think the intended direction centreline measuring described above would be sufficient as any off course run is only loosing potential distance and there is no gain to be had by going off course. ie: Longest distance will be gained by making a perfectly straight run.

> Car being in contact with the ground
I think the car needs to be in contact with the ground 99% of the run. We have seen the cars rear wheel hop off the ground at launch for 1/3 of a second or so, so the rule shouldn't mandate 100% contact but it needs to ensure the car is not a plane with skids

wow .. I know that was a lot so if you read this far well done :)

-todd-


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Re: Thampson WR-car record

Post by WRA2 » Sun Oct 24, 2010 1:14 pm

thampson wrote:Hi all, I haven't checked the forum for a coupe of weeks, so here is my input to this discussion.

> Todd, What parameters did you build your car to?
I dont know if I initially built it to any particular specification. Our main goals were safety, stability then distance. From a safety perspective, we always had multiple points where the pressure vessels were tethered to the chassis, usually 2 separate points per bottle. The chassis had one point (a riser between the bottles) where the bottles exert force on the chassis, this also enables the bottles to be held in place and not separate from the chassis (assisted by the bottle tethers). Our launcher has always had an abort and a rope activated quick release so it can be launched from a distance. We have always had 4 wheels, may want to limit this as the minimum.

>Camera
We have only recently added the camera but I think for record purposes onboard camera is a must, realistically they are very cheap these days, so this isnt cost prohibitive. Ground video is also good to show the start location and where it ends up, again most people have a video camera of some description that can be used for this purpose.
Having the onboard camera will also provide "interesting video" to use to promote the hobby. I will add the requirement to the draft.
thampson wrote: >Weight Limit
I dont know if an upper weight limit is necessary as it usually only slows the car down and it will help the cars stability and not let it off the ground. On the other hand a minimum weight limit may be required as the very light cars have a tendency to get airborne and flip which can be dangerous. However once a car flips or gets airborne it wouldn't qualify as a car so it couldn't break the record.
Good points about the weight being a self correcting issue. Since these will not fly we do not have to limit the weight to 1500 grams to meet the hobby rocket classification. We should still discuss if a maximum is needed to keep the costs under control.
thampson wrote: > 2 runs in opposite direction
I think this is a must, averaging the runs within a time limit ie: 2hrs, will ensure that any slope doesnt unfairly add to the distance or speed. Also it way be worth limiting the difference between the 2 runs to no more than 25%. So for example if one run was 400m down a hill and the second was only 10m back the other way, the average is 205m which is obviously an unfair method of taking a record. So with the 25% rule, if the first run was 10m and the second was more than 14m, then it would be more than 25% difference and the second run would either not count or would only be allowed to be 14m as a maximum.
From our experiences reviewing record submissions the average of two runs should be good enough. A car capable of going 400 meters "downhill" but only running 15 meters "uphill" on the same track will most likely go 200 meters on flat ground. The two hour time limit reduces the opportunity for a competitor to "cherry pick" their runs and forced the use of consecutive runs. Maybe that is the answer to make the rule as follows. The record distance will be the average of two consecutive runs in opposite direction (one rune each way) within a 2 hour time period. 2 hours should be long enough to refuel and setup a run in the opposite direction.
thampson wrote: > Metal Parts
Couplings - I think for this class that this may need more debate. We use aluminium robinson coupling which weigh in at about 10grams. Other plastic tornado type coupling weigh around the same ~8 - 13g. So whether its metal or plastic in the case of an explosion and seperating from the car the plastic and metal parts will still impart the same force if they hit someone. In an explosion the couping always stay attached to parts of the bottle, ie: its usually the bottle that rips/tears starting the explosion, its then a matter of containing the pieces. With water rockets cars we have an advantage over the vertical rockets in that we have a chassis to tether the bottles to. In our car design we have the 2 points per bottle as well as the riser to ensure the bottles doesnt separate from the chassis and fly off. To provide additional safety we have been working on a robinson coupling kevlar tether which tethers each of the actual couplings to the chassis, similar to the way F1 cars tether the wheels to the chassis so they no longer separate from the car in a crash. I believe this is a safer alternative than just mandating non metal parts whilst not mandating tethers. If a tether is mandated then there is no difference whether the coupling is metal or plastic.
What about containing the pressure vessel inside a wire cage mounted to the chassis?
thampson wrote: > Wind Speed should be measured
I dont think its relevant to adding to distance substantially, the run in the reverse direction would even out any gains anyway. We have launched the car in 50kmh wind and it really didnt make a noticeable difference to distance or speed.
Agreed.
thampson wrote: > The Floor type must be categorized
I wasnt sureif you were referring to the floor of the car ie: chassis or the road surface.
If its the floor of the car - I think this should be left open to allow for different designs. As long as the chassis provides sufficient locations to tether the bottles it shouldn't matter its construction. If 2 tethers per bottle is mandated then the chassis design will need to conform to that rule.

If its the road surface then outdoor would stop inside smooth concrete etc as suggested, but maybe a class on grass might be an option, going 100m on grass is a lot more difficult than doing in on tarmac, also no vehicles to annoy you on the grass (although people may be an issue). Maybe a tarmac class and a grass class, possibly a snow/ice class as well ?
A rocket car/sled traveling on snow or ice would have an advantage over a wheeled version so I agree that the type of track used must be defined. Maybe we should limit it to either asphalt or concrete and expand it in the future though to simplify the starting of a new competition. Finding a smooth grassy area will be just as difficult and maybe even more difficult then finding a road or parking lot.
thampson wrote: > Launching on an active road
Realistically you are going to need to launch on a road if you want to find 150m of straight tarmac. We have tried car parks (too many damn concrete blocks), driveways (not long enough any more) so you can find places to test that are not on a road as such. Although there are plenty of cul-de-sac, dead end roads, industrial areas that can be found on the weekend with little or no traffic. You need to be sensible about where you launch and personnel safety. Most people that do come past us when we are launching are interested and slow down and sometimes stop just to take a look and see what it is we are up to :)
We should make this as part of the safety rules. We should also specify safe distance from the track that all spectators must be. I think that because the car travels horizontally, that this is even more important then with vertical rockets. These are missiles traveling at ground level so people on the ground will be in more danger.
thampson wrote: > Stomp rockets
I dont have any issues with stomp rockets being banned from this competition.
Agreed, stomp rockets have no place here.
thampson wrote: > Steering
This should be left to the designer as to whether they want active (r/c) or passive (fins) steering. Experience tells me that if you seriously want to go after a distance record you are going to need to steer it. R/C Steering is the obvious solution and really not that difficult to build. I had never done r/c before trying it on our car, so if you can build a rocket car to challenge a record its well within your abilities to build the r/c steering for it as well.

The only method of steering which should not be allowed is attaching the car to a tensioned string/rope and letting it run along the string to keep it straight.
Agreed. the use of "guide wires" would be impractical. Imagine setting one up on an active roadway BO:
thampson wrote: > Method of measurement
The simplest and cheapest is marks on the ground. Take a tape measure and mark every 10m. Although its a good verification to check with google earth, which is pretty accurate. As long as you have a reference point, ie: driveway, bend in the road, gutter grate etc which is visible from google earth as the starting location. If the ground marks + google earth are a close match then this would suffice. When we were going distances of 30-45 m the google earth errors were noticeable, but now that we are around 150m google earth is very accurate as a method of confirming distance.
I think that marking on the ground is the best way. The teams can use "local measurement" (feet or meters in groups of 10) and measure from the last marker to the car after a run is completed. This can be recorded with a video camera (a creative team may place the markers so that the onboard camera can see them as they are passes so the onboard video will also provide evidence as to how many markers were passed).
thampson wrote: > Vehicle Track
The width of the car between the wheels (track) is one element of the design which can effect stability. Overcoming thrust steering is the difficult part of which a wider track helps but by no means would it cancel it out. Although making a car 1m long with a track of 3m probably wouldnt be in the spirit of the competition. Perhaps limiting the track width to no more than twice the length of the car may be worth considering.
I can agree to that.
thampson wrote: > How much off course would be considered acceptable
The more you go off course the less the distance is anyway so I would think we should accept cars not going perfectly straight. However when it comes to measuring the run, the measurement needs to be in a straight line from the starting location to the finish location, ie: you dont count the off course metres. Alternatively when the 10m marks are layed out on the road/ground, you can nominate a centreline (ie: you intended direction), then when the car comes to rest the measurement is done along the centreline to a distance no further then where the car comes to rest, ie: you only measure that vector of the distance so all off course metres traveled are not counted.
I like that. It gives incentive to having the car go in it's intended direction.
thampson wrote: > Does a car need to run in an intended direction to count
Generally to meet the 2 runs in the opposite direction, cancel the hills and wind assistance you would need to do the runs 180 degrees apart, maybe along the intended centreline as above.
I like the "centerline" idea to ensure that 2 runs are 180 degrees apart.
thampson wrote: > What if the car makes a 90 degree turn along the run
Its probably going to hit something .. like a gutter .. LOL ... :) ... seriously though, if we use the centreline ,measuring method above any turns along the course just loose potential distance, so there is no advantage in designing a car that snap turns along the run.
AG
thampson wrote: > More then a few degrees off the launched direction would make that run ineligible
Getting a car to go straight is very difficult .. a lot harder than it looks ... if we only allow a few degrees we are not going to get anyone setting any records .. :) I think the intended direction centreline measuring described above would be sufficient as any off course run is only loosing potential distance and there is no gain to be had by going off course. ie: Longest distance will be gained by making a perfectly straight run.
AG
thampson wrote: > Car being in contact with the ground
I think the car needs to be in contact with the ground 99% of the run. We have seen the cars rear wheel hop off the ground at launch for 1/3 of a second or so, so the rule shouldn't mandate 100% contact but it needs to ensure the car is not a plane with skids

wow .. I know that was a lot so if you read this far well done :)

-todd-
Couls we take advantage of the "ground camera" to tell if the car is simply flying horizontally? If the camera was setup viewing the run from the launcher looking down the "centerline" of the course it could be seen if the car way "flying". PH:


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thampson
Current WRA2 Dragster Speed & Distance Record Holder
Current WRA2 Dragster Speed & Distance Record Holder
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Re: Thampson WR-car record

Post by thampson » Mon Oct 25, 2010 8:08 am

Another Item I did think of was hot water/steam propulsion. This type of propulsion should not be included in this category.

> We should still discuss if a maximum is needed to keep the costs under control.
I think we could possibly have a 2.0L class and an unlimited class so that if cost was an issue you could still compete in the 2.0L class

> A car capable of going 400 meters "downhill" but only running 15 meters "uphill" on the same track will most likely go 200 meters on flat ground.
I dont think this is the case, If I had a nice downhill slope and a long enough road I could launch the current car at 20psi down the hill and steer it for 400m, whereas 20psi on the flat would go maybe 10m. I think having both runs within a percentage of one another will ensure this type of record attempt doesnt happen.

>What about containing the pressure vessel inside a wire cage mounted to the chassis
Thats an interesting concept, the cage will hinder any fragmented sections of bottles from flying off if there is an explosion, something like chicken wire would be light enough. It would need to be offset from the bottles slightly to allow for expansion of the bottles. I would recommend that this be as an addition to the bottle tethers. The question would be whether this type of protection is mandatory or not ?

>We should make this as part of the safety rules. We should also specify safe distance from the track that all spectators must be. I think that because the car travels horizontally, that this is even more important then with vertical rockets.
Agreed, When we launch everyone needs to be behind the rocket car and launcher.

>Could we take advantage of the "ground camera" to tell if the car is simply flying horizontally?
We currently have our camera mounted looking forwards and the front wheels are clearly in view and on the ground as a method of confirmation. As long as the onboard camera shows the wheel(s) on the ground I think that would suffice.

regards
-todd-


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