HELP PLEASE where will my rocket land?

[Scott Chase]

I have a very small field that I use for rocketry and it is surrounded by water sometimes I get them back and other times I go swimming. Can you please help me? Is there a functioning app or online calculator that can simulate where my rocket will land? is there an equation that I can plug the values in to get an idea of what's going to happen?

 

[boatgeek]

The simplest way is to know what your flight time is and measure the wind speed. If the wind is 5 feet/second, and your flight time is 20 seconds, your rocket will land about 100 feet away. It's not 100% that easy, but that's a good start. You should also be flying the field--use smaller motors on windy days, set up your launch pad toward the upwind side of the field, and point the launch rod into the wind. Finally, resist go fever. Don't launch when it's too windy to recover.

 

[Mr Rocket]

Open Rocket is a free downloadable app that allows you to simulate your flights. You can plug in the wind speed and plot a side view to see how far the rocket will drift. You can even change the launch rod angle to see the effect of that on the flight.

That being said, it's not always that simple. At a launch last weekend, the winds were about 4mph with gusts to 6-7mph. However, these were the ground level winds. The winds aloft were dead calm. We watched as rocket after rocket descended almost straight until it got to between 50 and 100' and then started drifting with the winds. I have also seen the reverse, where winds seemed dead calm, but the winds aloft were really cruising. It is very difficult to find all of the data needed to get an accurate prediction. If the sun is out, it can heat up paved surfaces or other items, causing an updraft of heated air called a 'thermal'. If this happens and your chute gets caught in one then all bets are off. I have seen rockets actually start to raise back up and drift away. I have also seen winds blowing in one direction at ground level and in a completely different direction aloft

Nothing beats experience. After awhile you will get a feeling for how different rockets behave in different conditions. At launches, the first rocket I send up is my test flight to see what the winds are doing. I usually use a small rocket that I am not too attached to, just in case the winds are not doing exactly what I think.

Some of the guys who do competition flying for duration may have some better tips

 

[kuririn]

So you've downloaded Open Rocket and plotted the side view profile and found out that with the given wind speeds your rocket is going to drift off your field into the water. What now?
There are a few things you can do to minimize wind drift:
1. Use a smaller motor.
2. Sub a streamer for the chute.
Pros: Rocket comes down faster, minimizing wind drift.
Cons: Rocket comes down faster, increasing the chance of landing damage.
3. Reef your shroud lines or cut a hole in the chute canopy.
Pros: As in #2.
Cons: As in #2.
4. Angle your rod to compensate for wind drift, but no more than 30 deg. per NAR rules.
Pros: Could reduce wind drift and landing distance from the pad.
Cons: Could result in rocket landing off the field in the opposite direction of wind drift
(i.e. overestimating wind speed or if rocket windcocks instead of a straight line trajectory).
Also as mentioned wind conditions can be very different at altitude compared to the ground.
5. Buy a JLCR (Jolly Logic Chute Release).
Pros: You can program the altitude at which the JLCR activates, minimizing drift.
Cons: Expensive, does not fit anything smaller than a BT-60 tube.
6. Find a bigger field.
As always, experience is your best guide.

 

[Scott Chase]

The simplest way is to know what your flight time is and measure the wind speed. If the wind is 5 feet/second, and your flight time is 20 seconds, your rocket will land about 100 feet away. It's not 100% that easy, but that's a good start. You should also be flying the field--use smaller motors on windy days, set up your launch pad toward the upwind side of the field, and point the launch rod into the wind. Finally, resist go fever. Don't launch when it's too windy to recover.

Thanks it is really close to an openrocket simulation.
Using your method the distance rolled out to be 89.54 and openrocket simulation 100.

 

[Scott Chase]

Open Rocket is a free downloadable app that allows you to simulate your flights. You can plug in the wind speed and plot a side view to see how far the rocket will drift. You can even change the launch rod angle to see the effect of that on the flight.

That being said, it's not always that simple. At a launch last weekend, the winds were about 4mph with gusts to 6-7mph. However, these were the ground level winds. The winds aloft were dead calm. We watched as rocket after rocket descended almost straight until it got to between 50 and 100' and then started drifting with the winds. I have also seen the reverse, where winds seemed dead calm, but the winds aloft were really cruising. It is very difficult to find all of the data needed to get an accurate prediction. If the sun is out, it can heat up paved surfaces or other items, causing an updraft of heated air called a 'thermal'. If this happens and your chute gets caught in one then all bets are off. I have seen rockets actually start to raise back up and drift away. I have also seen winds blowing in one direction at ground level and in a completely different direction aloft

Nothing beats experience. After awhile you will get a feeling for how different rockets behave in different conditions. At launches, the first rocket I send up is my test flight to see what the winds are doing. I usually use a small rocket that I am not too attached to, just in case the winds are not doing exactly what I think.

Some of the guys who do competition flying for duration may have some better tips

Thanks for the information I adjusted and plotted altitude-reference area and time. I also adjusted the wind direction speed chute sizes etc. What I learned from your suggestions was that launching from the very end of the field either north or south was my error. From the plots I was able to determine that I needed to move up to the next
area of asphalt on the field about 50 yards north or south depending on the wind direction. The plots clearly showed that from the new launch location I'm able to launch a loc 49"L- 2.14"D F23J motor 12" chute and 5 degrees on the rod into the wind. This allowed the rocket to reach the desired apogee of 800 feet with no recovery problem. I hope there will be no more swimming or sunken rockets.
Thanks Again

 

[Scott Chase]

So you've downloaded Open Rocket and plotted the side view profile and found out that with the given wind speeds your rocket is going to drift off your field into the water. What now?
There are a few things you can do to minimize wind drift:
1. Use a smaller motor.
2. Sub a streamer for the chute.
Pros: Rocket comes down faster, minimizing wind drift.
Cons: Rocket comes down faster, increasing the chance of landing damage.
3. Reef your shroud lines or cut a hole in the chute canopy.
Pros: As in #2.
Cons: As in #2.
4. Angle your rod to compensate for wind drift, but no more than 30 deg. per NAR rules.
Pros: Could reduce wind drift and landing distance from the pad.
Cons: Could result in rocket landing off the field in the opposite direction of wind drift
(i.e. overestimating wind speed or if rocket windcocks instead of a straight line trajectory).
Also as mentioned wind conditions can be very different at altitude compared to the ground.
5. Buy a JLCR (Jolly Logic Chute Release).
Pros: You can program the altitude at which the JLCR activates, minimizing drift.
Cons: Expensive, does not fit anything smaller than a BT-60 tube.
6. Find a bigger field.
As always, experience is your best guide.

Thanks for the info you always come thru with the RIGHT STUFF!

 

[Voyager1]

You can use an addon for OpenRocket that allows you to apply multilevel wind data. Down load it from https://github.com/rocketsam2016/MultiLevelWind/releases/tag/latest
and instal it in the same folder that you have OpenRocket in. You can get multilevel wind data from the US National Weather Service aviation forecasts. Also use local forecasts and site measurements for the lower level wind.

you can read the instructions for its use in another thread at https://www.rocketryforum.com/threa...peed-direction-at-different-altitudes.140619/

 

[Scott Chase]

You can use an addon for OpenRocket that allows you to apply multilevel wind data. Down load it from https://github.com/rocketsam2016/MultiLevelWind/releases/tag/latest
and instal it in the same folder that you have OpenRocket in. You can get multilevel wind data from the US National Weather Service aviation forecasts. Also use local forecasts and site measurements for the lower level wind.

you can read the instructions for its use in another thread at https://www.rocketryforum.com/threa...peed-direction-at-different-altitudes.140619/

When I download the file in windows I see it and move it to the openrocket files and try to open it in openrocket I can't see the file. Do you know what i'm doing wrong?

 

[Voyager1]

When I download the file in windows I see it and move it to the openrocket files and try to open it in openrocket I can't see the file. Do you know what i'm doing wrong?

Sorry, I should have been a bit clearer. You need to place the MultiLevelWind.jar file into the OpenRocket Plugins folder. This folder will be found in C:\Users\YourFolder\AppData\Roaming\OpenRocket\Plugins where "YourFolder" is probably your name. Follow the instructions in the thread I attached above?

How to use:
1) Download the MultiLevelWind.jar file
2) Copy MultiLevelWind.jar to your open rocket plugins directory. On a Mac, you can find this directory by:
a) Go the Finder
b) Hold down Option, click on the “Go” menu, and click on “Library”
c) Open “Application Support”
d) Open “OpenRocket”
e) Open “Plugins”
f) Copy the MultiLevelWind.jar file to that folder
3) Open OpenRocket
4) Create a Simulation, edit it, go to Simulation Options, and click “Add Extension”
5) Choose “Multi Level Wind” under the “Flight” category
6) Configure your winds! The default altitudes are the altitudes reported by “NAM 3km” model in the WindyTy app.
7) Plot your simulation with “ground track” to see the path of your rocket, and edit your launch rod angle and direction to find something that lands where you want

I don't have the "ground track" showing in my OpenRocket version (the latest), but you can select Lateral Distance and Lateral Direction, or Position East of Launch and Position North of Launch in the simulation options.

Even without this plugin, you can still just use the normal simulation launch conditions to enter the local wind speed and direction. If you're only launching to a few hundred feet on a smallish field, then this is probably all you need. You can still plot the rocket's position as described in the paragraph above.

 

[BABAR]

I dunno, all other things being equal my rockets tend to land wherever they want to, which unfortunately is infrequently where I want them to.

 

[Bat-mite]

I dunno, all other things being equal my rockets tend to land wherever they want to, which unfortunately is infrequently where I want them to.

No simulation can take into account that rockets are biologically attracted to roofs, streams, puddles, ditches, power lines and trees.

 

[Scott Chase]

No simulation can take into account that rockets are biologically attracted to roofs, streams, puddles, ditches, power lines and trees.

That's Funny and sadly true!

 

[c0c0m0ke]

The following was also posted to "Ye Olde Rocketry Forum," under the thread, "Integrating Google Maps, ThrustCurve and OpenRocket"

Has anybody ever used Google Earth to locate a missing item?

On Feb 29th, I launched my rocket, on a relatively windy day, winds were just below the 20/mph upper limit. I am new to hpr. The motor, wasn't suited for the rocket.

My motor retention system was a jury rigged bent coat hanger. Because of the gusting, I was afraid that the igniter would drop out of the motor, so I laced it thru the "hanger". At ignition, the rocket seemed to lift up and pause for an instant and then resume its ascent. As soon as it cleared the end of the rail, which eas pointed straight up, or nearly straight up, the rocket tilted over to somewhere between a 45 degree to a 60 degree angle of ascent. I am a older codger, so my eyes aren;t as sharp as they used to be, I lost sight of the rocket. I am reliant on better eyes of my colleagues. Arms out stretched, they pointed the direction they last saw my rocket go.

It's pretty flat here on the east coast of Florida. We launch in an area about 3 miles square, interlaced with a number of paved roads but devoid of human habitation or edifices. We are appreciative of our RC bretheren, who, over the years have kept the wild and wooly ever growing tropical jungle to somewhat tamed savannah -- or what I imagine pampas might look like. One can see acres and acres of grass occasionally interrupted with lines of trees. The grass is anywhere from 6" high to 4 feet high. More often it is the latter we have to reckon with.

Some of us print Google Maps of the area, and when one of our errant missiles fall from our view in a direction, someone will whip out a compass, get a bearing and plot the whereabouts with a protractor and straight edge.

It took a couple of hours, but I found my rocket, or what was left of it. It crashed about 3000 feet from the pad, almost due north. It flew over 5 cross streets, two dried up ditches that are lined and full of trees, and more acres upon acres grass 10" high with deep thatch to boot. And don't forget, patches of 4 foot high grass.

The reason the rocket crashed is, the hanger, instead of being perpendicular to the motor mount, was turned tangent to it, and the motor ejected itself, rather than the parachute. I lost an brand new altimeter and my trusty Chute Release in the transaction.

I have walked the flight path, and wide of it to either side, a number of times to no avail, looking for the missing motor casing. I found someome else's lost Rocket. Near that one, I also located the skull of some mammalian critter. And a golf ball. A half inch wide band about 1/8" thick and more than 20 feet long that loops in the air 4 feet up, anchored to who knows what is underground at both ends? I tried to dislodge it, but when I failed the first time, I decided it wasn't my problem.

I took my metal rake out there dragging it about hoping to encounter the motor casing, but that is a lot of area to cover for one person. I have turned over a lot of thatch. Would I be better using a metal detector?

I looked at the simulations in ThrustCurve and OpenRocket. The motor burned propellant for 7.5 seconds, and the delay lasted for 9 seconds. One of the apps predicted the flght to last last 36 seconds. 16 or 17 seconds into th flight, I can safely assume my motor ejected. That would be no where near the crash sight, but some where near the middle? How much forward momentum does a rocket motor lose when it ejects? Do I divide my flight path into 36 equal parts and start at number 16 to begin my search? And can I say for certain that is how long the flight actually did last? Coulllld it have been more? or less? Does the entire flight time really matter? Should I start aat the halfway mark and work my way back to the pad, or go the other way toward the crash site? How wide of the flight path should I search? 25 feet? 50 feet? 100feet?

Any advice or insight, would be appreciated.

 

[Aysenur]

Hello,
What I am trying is to estimate the position where the rocket will be landed. I have to use the data from the telemetry module which we are using. For the trajectory of it, It’s not a guided rocket but it will deploy parachutes (first one at the apogee (the highest point) and the second one at the pre-determined altitude). In terms of ground course, we are expecting it to be a straight line plus the effects of wind. Since we are not experienced in Kalman filtering, we decided to use a basic regression but the problem is since the data we will use will come from the telemetry module and our packet loss rate depends on the distance, there will be much more observations at the beginning of the flight compared to the end of it. We afraid that this might jeopardize the performance of the regression since the trajectory of the rocket will change after the deployments of parachutes. Other than that since the rocket will be far away we are expecting to have a really limited amount of observations (3-5) after the second parachute deployment.
Any suggestions?

 

[Voyager1]

What processor system are you using? There are free Kalman filter libraries available for Arduino, Raspberry Pi, etc. Most are easy enough to implement in your code, and they work well with optimised parameters.

How far is "far away"? What is your telemetry path budget? What error checking are you employing?

Why would you only be expecting 3-5 observations after deployment? Is that per second or in total?

 

[OverTheTop]

Estimating where your rockets land is part of the skill of flying. Working out whether they will weather-cock upwind or how much they drift downwind is a bit of an art, but you can minimise your walks if you think about it.

Using sims is a good way of helping you estimate the LZ. It does take a bit of practice.

Figuring out which chute to use, where to situate the launch pad, on what angle to fly and when to push the button are all in the control of the rocketeer!

 

[Voyager1]

Estimating where your rockets land is part of the skill of flying. Working out whether they will weather-cock upwind or how much they drift downwind is a bit of an art, but you can minimise your walks if you think about it.

Using sims is a good way of helping you estimate the LZ. It does take a bit of practice.

Exactly! Using sims can give you a very good idea of where you will land, particularly if you employ the multilevel wind addon to OpenRocket using forecast multilevel wind data for the area that you launch in. See post #8.

 

[OverTheTop]

Other than that since the rocket will be far away we are expecting to have a really limited amount of observations (3-5) after the second parachute deployment.

You should have more packets than that after apogee. If you are concerned about packets after main has come out you can pop that earlier. I personally use around 1800-2000' so that there are more packets out of my tracking system before it lands. Once landed the signal level drops significantly, but if you look at the last location before landing it is usually very close. As you get closer to the rocket you might make radio contact again and get an updated position.

How far away are you expecting?

 

[rlhatcher]

This may be of interest https://sourceforge.net/projects/camrocsim/

 

[Voyager1]

This may be of interest https://sourceforge.net/projects/camrocsim/

It’s a very useful application, particularly with its 3D Monte Carlo plots. The original design interface was not great, but now it employs an OpenRocket user interface. I’ve been using it for a few years now.

 

[Aysenur]

What processor system are you using? There are free Kalman filter libraries available for Arduino, Raspberry Pi, etc. Most are easy enough to implement in your code, and they work well with optimised parameters.

How far is "far away"? What is your telemetry path budget? What error checking are you employing?

Why would you only be expecting 3-5 observations after deployment? Is that per second or in total?

We use Arduino Mega 2560. How can I ımplement it? Our telemetry can send data from 3km, but it sends less data in longer distance like , 3 datas in 65 seconds. The time after the main parachute opens is about 70 seconds so we could get 3 or 5 location datas. This situation makes our estimation unreliable. BTW our rocket will lands 3kms far away from us.

 

[Aysenur]

You should have more packets than that after apogee. If you are concerned about packets after main has come out you can pop that earlier. I personally use around 1800-2000' so that there are more packets out of my tracking system before it lands. Once landed the signal level drops significantly, but if you look at the last location before landing it is usually very close. As you get closer to the rocket you might make radio contact again and get an updated position.

How far away are you expecting?

What do you mean "packet" ? I want to have an estimation by using location datas because I could lose the data connection while rocket is still on flight. In this way, I hope , I could still find the rocket. I use some numerical methods but it is not affective. I determined a path and test the reggression.

time=(0:10:80)'; %matematiksel metodu kullanabilmek adına temsili bir zaman aralığı belirledim
latitude = [41.324729, 41.323208, 41.321382 , 41.323086 , 41.323512 , 41.326006 , 41.328622, 41.329656, 41.332090 ]'; %enlem verileri
longtitude = [26.810825, 26.814471, 26.817654 , 26.823382 , 26.828486 , 26.831727 , 26.836426, 26.840557, 26.844203 ]'; %boylam verileri
data = table(time,latitude,longtitude); %enlem ve boylam verilerinden data table oluşturulur.
subplot(2,2,1);plot(time,latitude,'o'); xlabel('Zaman , sn'); ylabel('Enlem , DD'); title('Enlem-Zaman '); %enlem ve boylam verileri grafiklerini çizer
subplot(2,2,2);plot(time,longtitude,'o'); xlabel('Zaman , sn'); ylabel('Boylam , DD'); title('Boylam-Zaman ');


p_latitude=polyfit(data.time, data.latitude,5);%enlem için 5.dereceden polinomik denklem oluşturur.
p_=polyfit(data.time, data.longtitude,5); %boylam için 5.dereceden polinomik denklem oluşturur.

p_latitude_2=polyfit(data.time, data.latitude,3); %enlem için 3.dereceden polinomik denklem oluşturur.
p_longtitude_2=polyfit(data.time, data.longtitude,3); %boylam için 3.dereceden polinomik denklem oluşturur.

%Burada 5.dereceden ve 3.dereceden denklemlerin oluşturulma nedeni bu iki
%yaklaşımın ayrı ayrı nasıl davrandığını gözlemlemektir.


t=1;
i=10;


while i<105
    
    predict_latitude1(t)=polyval(p_latitude,i); %oluşturulan 5.dereceden enlem denklemine data table'daki değerler girilir
    predict_longtitude1(t)=polyval(p_boylam,i); %oluşturulan 5.dereceden boylam denklemine data table'daki değerler girilir
    
    predict_latitude2(t)= polyval(p_latitude_2,i)  %oluşturulan 3.dereceden enlem denklemine data table'daki değerler girilir
    predict_longtitude(t)= polyval(p_longtitude_2,i)  %oluşturulan 3.dereceden boylam denklemine data table'daki değerler girilir
    
    i=i+5;
    t=t+1;
    
end
% disp(enlemTahmini);
% disp(boylamTahmini);

t=1; i=10;
subplot(2,2,3);

geoscatter(latitude,longtitude,'p','y'); title("Beşinci Dereceden Polinomik Yaklaşım");
while i<105
    
    hold on
    geoscatter(predict_latitude1(t),predict_longtitude1(t),'*'); %5.dereceden polinomik yaklaşımı haritada çizer
    hold off
    
    t=t+1;
    i=i+5;
    
end


t=1; i=10;
subplot(2,2,4);

geoscatter(latitude,longtitude,'p','y'); title("Üçüncü Dereceden Polinomik Yaklaşım");
while i<105
    
    hold on
    geoscatter(predict_latitude2(t),predict_longtitude(t),'*'); %3.dereceden polinomik yaklaşımı haritada çizer
    hold off
    
    t=t+1;
    i=i+5;
    
end

 

[OverTheTop]

What do you mean "packet" ?

Data usually gets sent to the ground in packets that get resent on a regular basis. Each packet of data contains all the required data to be communicated and also the relevant preamble and postamble to successfully decode and verify the data within.

Most telemetry systems we use send GPS data around once every second, and there is other information available in the burst as well. Some systems use slower but from my experience the one second rate is quite common.

Our telemetry can send data from 3km, but it sends less data in longer distance like , 3 datas in 65 seconds. The time after the main parachute opens is about 70 seconds so we could get 3 or 5 location datas. This situation makes our estimation unreliable.

So you either have a really slow data rate or very big packets. What baud rate are you running on the telemetry? You can increase your data rate if the communication system can tolerate it, or reduce the amount of information in the packet. You could also use a larger parachute .

You could also have different packets, with more important information coming more frequently, and information that is less important in other packets less frequently.[/QUOTE]

 

[Voyager1]

See Data Packet definition.

I agree with OTT that you would be better off deploying your main chute at a higher altitude, therefore allowing a greater number of GPS fixes ("packets") for your prediction algorithm to give you a better chance of extrapolating to a predicted landing point. Just remember, any prediction algorithm is only as good as the quality and number of data points that you use. Only send back data that you really need and, as OTT suggests, optimise your transmission baud rate and packet content.

I understand what you are trying to do with your Matlab code, but you might be better off using the last known reliable GPS coordinate that you receive and plot a point on the ground below that coordinate. You would then apply known wind direction and speed, together with rocket descent rate, to estimate your final ground track and landing position. That method would probably be simpler and more reliable than what you are trying to do with your prediction code. You could also use a combination of both methods.

From the output of your prediction code, the predicted path appears to diverge fairly quickly from your known coordinate points - assuming I'm reading it correctly.

 

[Voyager1]

You might like to checkout the Cambridge Rocketry Matlab Toolbox. There is a function (descentcalc.m) that simulates the descent of the rocket under parachute from a specific coordinate in 3D space. It employs a wind profile and parachute parameters to simulate the descent. There are many other useful functions, too.

The link is CRTMatlab. This is a related link to the one provided by rlhatcher, above.

 

[Big-Bob]

I have never had much luck predicting where a rocket will come down. The wind at 3000+ feet is often very different from the wind at ground level. I have had them drift over half a mile. If you have a very small launch site, you are pretty much stuck with low powered engines. That doesn't work for me because my main focus is trying to go as high as I can with low power rocketry (up to D engines) I often have to drive long distances to find a place large enough. I try to find a place one mile square, and launch from as close to the middle of it as possible.

 

[Sabrina]

Guarantee your rocket will land on the earth. Gravity is a universal constant. - Rockets that go up, will come down - no doubt about it.

There are too many variables to be able to predict - exactly where your rocket will come down.

With practice, you might be able to predict a general direction. In a small field - a smaller chute or streamer will help. Don't be afraid to adjust the recovery method.

The practice and familiarity you gain after tens or hundreds of launches will help you more than any app, or computer program.

Try reading a book - "The Handbook of Model Rocketry" by Stein is a good one. That book plus lots of practice is your best bet.

Also - I noticed Cape Coral - I have family there. One of my favorite places!!

 

[RocketTree]

I would suggest Openrocket or Rocksim, along with current weather conditions, a GPS (or google earth view) of the launch site. Simulate and measure based on the conditions that day. Launch a "wind test" rocket before you fly anything of value to confirm the landing zone. Adjust the launch rod as needed and have a great time with fingers crossed. Not much more you can do since each rocket has its own flight personality.

All the best.