What You Need

To do this project, you’re going to need a few materials:

• An RC helicopter, or RC airplane with 3 channel control or better – You’re going to need a stable platform to take pictures from. Helicopters are useful because you can hover in one position, but airplanes are cheaper. You might already have an airplane or helicopter around, but if you don’t, the Multiplex Easystar works well for this project. Note that to make a remote shutter function, more than 3 channels are needed.
• A lightweight camera, with remote shutter operation – You need to be able to remotely trigger the camera. This can be done a number of ways, but the simplest and most economical is to attach a servo to the top of your camera with rubber bands. Make it so that when you throw a spare channel switch on your transmitter, the servo arm will move and press down the shutter switch. As with any mod, feel free to create your own solution.
• A large protractor
• Some string and a weight – Clay works well as a weight, I’ll explain why you need it shortly.
• A drinking straw – You’re going to need this to build a sight for the protractor.
• Measuring Tape – You need to know the altitude of your aircraft, and to do this, you need to measure it’s distance from you. Landmarks with a known distance can also be used – consult any street map with a scale for these.
• A notebook / paper / pencil
• A friend to help – You can’t fly your aircraft and make measurements at the same time. Take a friend along to help you, and ask them to record the measurements.

The Math Involved

Now we come to the hard part – a little bit of math. You don’t really need to understand all these derivations, feel free to simply use the formula that I’ll give you. The problem is this: given an aerial picture, how can we figure out the scale?

We need the altitude of the airplane to figure out the image scale. This can’t be done directly, so we measure the angle (a), the distance (d), and use them to compute the height (h). This is a right triangle, and there are some handy trig functions that apply. In this case, we use the tangent function, which gives the ratio of the opposite and adjacent sides.  This is expressed as follows:

By taking the tangent of the angle a, and multiplying by the distance (d), we get the height (h). Here’s the formula that you would use:

So how do you get the angle? It’s simple: take the protractor and tape a piece of drinking straw to the flat bottom. Then attach a piece of sting to the bottom center of the protractor, so that it dangles straight down the 90 degree mark. Use the ball of clay to make a weight at the bottom of the string. Now, when you tilt the  protractor, the string will measure the angle. Be careful though: the angle with respect to the ground is not what’s read directly off the protractor scale. Reading the difference between the indicated angle and 90 degrees will give you the angle you need.

So why do we care about the altitude? Well, it turns out that the ratio of the altitude and the focal length of the camera is the image scale! You can find out the focal length of your camera by reading it’s manual. This is usually expressed in millimetres, so convert it to whatever  unit you have used to measured the distance, and thus the altitude in. Let’s put that all in a convenient formula:

And that’s the only formula you need. Just measure the distance, and the angle, know the focal length, and you’re done.

How to Do the Measurements

All that math was fun, but how do you actually measure distances using this method? I’ll illustrate with an example:

Suppose that you’ve just gone out to a field, and want to measure the distance between a tree and a building. The first step is to find a landmark you can fly over with a known distance. Using a measuring tape or map, you find that a nearby hill is 50 feet from where you’re standing. With a friend ready to measure and write down the angle, you launch your airplane and fly over the nearby hill, taking several pictures. Your friend sights the model aircraft through the protractor – straw device built earlier, and finds the angle to be 75 degrees.

Using a calculator, you find the altitude to be:

After landing, you download the pictures and print them full size, with no scaling. Your camera’s user manual reports that the focal length is 152 mm (millimeters). Converting this to feet is easy, just type it in Google or multiply by the number of feet per millimetre. 152 mm is 0.48 feet, so you plug that into the formula we derived earlier and obtain the following:

This means that distance measured on the picture is 0.000257 times as big as the real distance. You’re almost done: using a ruler, you measure the distance between the tree and building on the image to be 1 inch. Converting this to feet (because we want the distance between the building and tree in feet), gives a distance of 0.0833 feet. Now, multiplying this by 1 divided by the picture scale gives a final answer of 324 feet.

And that’s it – you’ve just measured the distance between two objects using nothing more than a RC aircraft, camera, and a little trigonometry. Just keep in mind that you have to know the distance between the airplane and you accurately for this to work – always take pictures right on top of the marker with a known distance.

© Draganfly Innovations Inc.
Phone: 1-800-979-9794 / 306-955-9907
Email: info@rctoys.com
Web: www.rctoys.com

The Mach IIIz is an indoor electric RC blimp, which uses helium gas in a mylar inflatable envelope for buoyancy.

Mach IIIz RC Airship Features

The Mach IIIz blimp features three channel radio control, which allows it to fly in any direction (up/down, left/right, and forwards/backwards, and spin in 360 degrees). Each channel controls one of three fans, which are mounted on the gondola. The gondola is the white plastic cabin, which is mounted on the bottom of the inflatable balloon envelope via clear tape. Two of these fans are attached side by side, and control the direction of the blimp. An additional fan is mounted on the bottom of the gondola, which controls altitude. Learn more about how RC blimps work.

The Mach IIIz blimp uses a small 3v lithium battery for power. Lithium batteries are very lightweight, making them perfect for usage in RC blimps. The battery is mounted in the gondola of the Mach IIIz, and provides power for both the electric motors and the radio receiver.

MachIIIz blimps also come in different frequencies, colors, and styles, so two blimps can be flown at the same time. High lift envelopes are available for customers above 4000 ft. If you’re into sc-fi, a UFO / flying saucer version is also available.

Mach IIIz blimps are perfect for flying indoors, but they will become lost if you attempt outdoor flight. Remember that the Mach IIIz is essentially a powered helium balloon, so even slight winds will carry it away. Because the MachIIIz is durable and easy to fly they make an ideal RC toy for kids. The MachIIIz is great for advertising when equipped with a plain silver balloon, or a white high lift envelope. You can print your own stickers, or use a soft felt tip marker to decorate the balloon. Flying this RC airship over any event is sure to get attention, and printing your own labels on the blimp envelope is easy.

Where to Buy an RC Blimp

Get RC Blimps, parts, and accessories at www.rctoys.com.

——
Draganfly Innovations Inc.
Phone: 1-800-979-9794 / 306-955-9907
Email: info@rctoys.com
Web: www.rctoys.com
RSS: www.rctoys.com/pr/feed

A remote controlled blimp is a lighter than air aircraft that relies on the principle of buoyancy. Buoyancy is the effect that causes less dense objects to rise when immersed in a denser substance. As long as a similar volume of one material is less dense than another, it will rise. RC blimps, airships and flying saucers make use of this buoyancy effect by using a lighter than air gas to fly: Helium. Because Helium is less dense than the air the blimp will float. The idea behind a blimp is to have the lifting force of the helium exactly cancel out the downwards pull of gravity. This is called neutral buoyancy. In order to rise or descend, the blimp fills or empties different compartments (ballonets) with air. Because air is heavier than helium, this will cause the blimp to decend. Emptying these ballonet compartments will make the blimp lighter and cause it to rise.

The First Blimps

The first rigid airships (also called Dirigibles or Zeppelins) were constructed in the early 20th century. Back then blimp aircraft consisted of a metal frame, covered with fabric and filled with a lighter than air gas like Helium or even Hydrogen. Below this balloon assembly was the gondola. The blimp’s gondola housed the pilot, crew, passengers, and engines. These airships were used for both war and civilian travel during the 20th century. A famous example of such a zepplin was the German Hindenburg airship, which was destroyed on May 6th, 1937. The Germans, who were unable to obtain helium gas for the airship, used hydrogen as the lifting gas. Hydrogen is explosive where Helium is inert. The Hindenburg disaster played a huge role in ending the use of huge blimps for passenger travel.

Modern Blimps

Modern blimp airships are non rigid, meaning that there is no internal structure to support the envelope. Modern blimps are filled with Helium, a safe inert gas, to make them float. Like the old rigid airships, modern blimps still rely on the principle of buoyancy to fly. Modern blimps are used primarily for advertising rather than passenger travel. If you’ve ever attended an NFL football game, NASCAR race, or PGA golf tournament you’ve probably seen the popular Goodyear blimp.

Remote Control Blimps

Radio controlled blimps are an excellent choice for someone new to RC and appeal to all ages. An RC blimp is just a smaller version of a modern blimp airship, except for a few differences. Instead of relying on ballonets (air-filled bladders) to change the weight of the blimp to rise or descend, neutral buoyancy is achieved by adding small weights or ballast putty to the blimp until it hovers. The RC blimp’s gondola is equipped with small electric motors with propellers used to propel the blimp up and down. Most electric rc blimps use a tri fan design, to provide directional control in every direction: up/down, left/right, and forwards/backwards. A good example of this are the Mach III Indoor RC blimps at RCToys.com. These R/C blimp aircraft are for indoor use only. Flying them outside will lead to them getting lost, or blown away. Remember, these aircraft are really helium balloons with motors and a radio, so make sure that you fly them where they cannot get away.

RC Blimp Balloons

RC blimps come with a super lightweight mylar balloon. These mylar rc blimp balloons are both durable, refillable and replaceable. For customers at altitudes greater than 4000 ft above sea level, a larger capacity high lift balloon is available. This white high-lift rc blimp balloon is also great for applying advertising stickers. This can be necessary because, as altitude increases, the density of air decreases, lowering the lift generated by the balloon.

Where to buy Helium for RC Blimp Balloons

Helium for the rc blimp’s balloon envelope is easy to obtain at wedding & party supply stores, flower shops, most grocery stores, and welding supply shops. Filling the rc blimp is also easy, the person selling you the Helium should be able to do it for you, if they have a mylar nozzle. After filling the envelope with Helium place a small piece of tape over the hole to keep the Helium in the balloon.

How to achieve neutral buoyancy so your RC blimp hovers

Chances are, after you have filled your blimp with Helium, it will try to climb. You can use either the weights included with the blimp, or some modeling clay (ballast putty) to correct this. Hang the weights on the rods supporting the engines, making sure to keep the weight equal on both sides. If you decide to use modeling clay, place it in the gondola, near the batteries. Using clay instead of the included weights will allow fine tuning the airship, so that it will maintain the altitude that you want it to. Add just enough weight so the rc blimp neither climbs or sinks.

Where to buy RC Blimps

Draganfly Innovations Inc. sells a huge selection of RC blimps and flying saucers. The most popular blimps are the RC Goodyear Blimp, the RC Airship America and the RC Blimp Bomber. Replacement r/c blimp parts, balloon envelopes and 3V lithium blimp batteries are all available at www.rctoys.com.

——
© Draganfly Innovations Inc.
Phone: 1-800-979-9794 / 306-955-9907
Email: info@rctoys.com
Web: www.rctoys.com
RSS: www.rctoys.com/pr/feed

Why would you want a high-lift super-size RC blimp envelope?
If you live at an altitude of over 4,000 ft the air density is too low to properly fly our 36 and 52 inch blimp and UFO balloons. The answer is this high lift blimp balloon. At 52″ x 37″ x 37″ the high lift balloon wider and taller than our regular blimp balloons/envelopes and holds 2 cubic feet more helium.

Another advantage of having a high-lift blimp balloon for your MachII or MachIII airship is the ability to hold advertising stickers and remain buoyant – and the white background is perfect for properly displaying your ads and logos.

Is it compatible with my RC Blimp?
Yes! The high-lift envelope is compatible with all our MachII and MachIII remote controlled blimps and flying saucers – including the RC Blimp Bomber and all 36″ and 52″ RC blimps from Interactive Toy Concepts Ltd. Simply remove your current balloon and attach this high-lift version.

Buy a high-lift r/c blimp envelope upgrade for your airship at www.RCToys.com – while supplies last. Looking for another replacement r/c blimp balloon? We have them as well.

——
© Draganfly Innovations Inc.
Phone: 1-800-979-9794 / 306-955-9907
Email: info@rctoys.com
Web: www.rctoys.com
RSS: www.rctoys.com/pr/feed

Your Batteries Are Low

The rc blimp requires one 3V lithium blimp battery and the transmitter requires one 9V battery. If the battery voltage in your transmitter or rc blimp is low it will have short range. Ensure that the batteries are new or fully charged. We carry replacement rc blimp batteries on our Web site or you can also purchase them at most convenience & camera stores.

Check the Gondola Antenna

Ensure that the antenna wire on the rc blimp’s gondola / fan unit is fully unwrapped, untied and fully extended. When your rc blimp is new out of the box this antenna wire is neatly wrapped for packing purposes only. When flying your rc blimp be sure to unwrap the antenna wire or you will suffer poor range and low reception.

Ensure that the antenna wire on the gondola / fan unit is not exposed through the insulation, or cut at the end. If the antenna is damaged or has bare wire it will have to be replaced. For a replacement please call us 1-800-979-9794 / 306-955-9907 or email sales@rctoys.com

Check the Transmitter Antenna

The hand held transmitter antenna is telescopic. Fully extend the transmitter antenna when flying your RC blimp. The transmitter antenna can be removed from the transmitter by unscrewing it. Make sure that when flying your rc blimp the transmitter antenna is tightly screwed into the transmitter.

——
© Draganfly Innovations Inc.
Phone: 1-800-979-9794 / 306-955-9907
Email: info@rctoys.com
Web: www.rctoys.com
RSS: www.rctoys.com/pr/feed

Check the Helium Gas You Purchased

Many shops sell weak or diluted helium gas. Weak/diluted Helium is commonly mixed with Nitrogen and will provide less lift, and in some cases, prevent the rc blimp from flying/floating. It is common that Nitrogen is mixed with Helium when filled into canisters. The less Helium, the less lift your rc blimp will have. To get the most pure Helium to fill your rc blimp we recommend contacting a welding supply store as they will typically have the best quality Helium.

What Altitude Do You Live At

If you are flying the blimp at a location where the altitude above sea level is greater than 4,000 feet (1,219 m), you may require a high lift blimp envelope. The higher above sea level you are the less lift the Helium will provide. Above 4,000 feet we recommend using the larger high lift blimp envelope that hold about 2 cubic feet more than the standard size blimp.

——
© Draganfly Innovations Inc.
Phone: 1-800-979-9794 / 306-955-9907
Email: info@rctoys.com
Web: www.rctoys.com
RSS: www.rctoys.com/pr/feed