The Hummingblimp

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Introduction: The Hummingblimp

About: Send me a message if you're interested in Technology or Science Workshops in Flanders, Brussels or the Southern of the Netherlands. I have over 15 years of experience in developing and giving creative worksh...
What do you get crossing a Zeppelin NT balloon with a Hyperblimp in a classroom? A Hummingblimp!

Check it out in this video:

As most of my projects involve something that moves I just had to partipate in the Make It Move Challenge". Lately I have been experimenting with building RC-blimps based on the balloons sold by Deutschen Zeppelin-Reederei GmbH. These balloons are about 120 cm long and 25 cm in diameter. Filled with helium these balloons lift a mere 20g. But modern micro RC-gear brings this within reach of anyone with some basic experience in building remote controlled models.

A classic gondola setup resulted in a blimp that is quite quick for its size and very agile. But at high power a lot of roll back and forth occurs. Positioning the main thrusters higher, closer to the centre of mass should remedy that. But instead of putting the thrusters on the sides (as in Zeppelin airships rather than blimps), I tried a single propeller at the stern, inspired by Daniel Geerys awesome Hyperblimp. As the complete controls and propulsion are at the stern, an even stricter weight limit is set for these parts (under half of the lift capacity, i.e. 10 g).  For this I came up with a setup around the Spektrum AR6400L Ultra Micro Receiver with integrated servo's. The battery goes on the bow.

The result is a lively indoor blimp suitable for spaces the size of a class room or larger. Controlling it in a smaller class room takes some practice (Im still on it). But it doesnt matter if you hit anything, you can just keep flying. Obviously you should avoid all hot, sharp or fragile objects in the room.

You do not need any flying skills, but this project does require a willingness to work with tiny, flimsy components. Some minor soldering is needed to extend the battery leads. 

Many thanks for all of your votes in the Make It Move Challenge.

Step 1: Materials:

The “Zeppelin NT” blimp balloon I used is no longer available, sadly. You can try a 40" letter I or number 1 balloon, but these are shorter and tend to give about 10 to 20% less lift.

99%+ Helium (have your balloon inflated at your local balloon shop, after preparing it as shown in step 2).

An ultra micro receiver with two servos and ESC (Electronic Speed Control) operating on a single cell rechargeable Lithium battery (1s Lipo). The Spektrum AR6400L brings al this, integrated on a tiny print at a mere 3,9 g.

A matching transmitter, I used a Spektrum DX6I, but a even the simplest, like the DX5E or the type that comes with RTF RC planes would work too. As long as it is compatible with the receiver.

A DC brushed motor under 4 grams (3 grams is better) and matching propeller. I used a motor from a micro servo and tested some propellers I had lying arround, but you can get both from Plantraco. They have great tiny motors and propellers. I would recommend the 57x20 prop for 1mm Shaft with the 7mm 3.3 Ohm motor with with nanoconnector.

A single cell lipo rechargeable battery 125 mAh, 4 g.

2.6 m of 0.14 mm2 wire and connectors matching battery and receiver.

Some scrap balsa, 1 and 4mm thick, and Tyvek (or other micro plane construction and hinge materials).

Some 3mm extruded polystyrene sheet (like Depron or Climaplan).

Two times a couple of cm of steel wire 0.8 mm diameter (or even thinner).

About 10 cm of light plastic tube, e.g. use with air filled latex balloons.

Superglue (regular or thin), cellotape, double sided tape.

Tools: soldering iron with adjustable temperature or simple soldering iron and a clothing iron, scissors, hobby knife, working surface.

Step 2: Preparing the Envelope or Balloon

The balloon is used backwards. What is the bow on the Zeppelin NT is the stern on the Hummingblimp and vice-versa. This is because the highest buoyancy and therefore the most volume is needed at the stern.

The Zeppelin NT balloons come with one tail fin and a gondola to be inflated. As these contribute more to the weight than to the buoyancy, they are removed for this project.

When inflating the balloon, the tail fin and gondola are filled through a couple of short interruptions in the seam. So before inflating, these interruptions are hot sealed. I use a soldering iron with adjustable temperature, set at its lowest temperature (about 200 °C) and with a broad tip (actually a tip broadened by a drop of solidified solder). I put some leather underneath the ballon when applying the seam. Leather resist the heat (at least for the short time needed) and allows to apply some pressure smoothly when making the seam.

Alternatively, you can use a clothes iron, but in that case I would cut of the fin and gondola first. You should do some tests to determine the correct temperature setting (a strong seam, but no wrinkling). On a clothing iron I used in similar projects i found the best setting to be just under "Wool".

Of course you can “weld” your own balloon completely from foil, but personally, I never managed to reach the same gas tightness as machine sealed balloons. Even when making long seams on commercial balloons, keeping the self sealing valve, the gas tightness is noticeably affected. On the other hand the short hand made seams do not seem to make a difference and the balloon remains to keep for one to several weeks.

Step 3: Yaw (left-right Steering)

The steering is set up, literally around the receiver-servo unit. A tiny balsa beam forms a back bone to which the receiver/servo unit is attached with double sided tape. Attachment is done only when the hinges and controls are finished after intermediate test fitting.

Each hinge is made out of Tyvek, glued on balsa and soaked with superglue to reinforce. After the glue has set the hinge is loosened up by moving back and forth a couple of times.

Each control horn is made out of a 1mm thick balsa triangle, strenghtened by soaking with superglue. The lever length of the horn should be close to half the servo travel.

Step 4: Pitch (up-down Steering)

The hinge for the pitch is made in a similar way, on the other side of the reciever/servo unit. First a 1,5 cm balsa "beam" is glued in a "T" to the main beam. It is important to put the pivot point high enough to make room for the motor connector and to make sure the control rod can move freely when "giving down".

Here the "moving part" of the hinge is chosen larger as it will actually become the fixed support to be attached to the blimp. Three balsa "beams", are glued to this part, to be attached to the inflated balloon. They are stuck on the balloon with some double sided tape, one by one. This is done by removing the protective layer on the second piece of double sided tape only after the first is stuck in place. T The third one is done proceeding the same way.

Step 5: The Leads

The battery leads are extended to cover the length of the balloon, with about 10 cm extra. For this I extended a “Ultra-Micro Connector -to BEC connector” conversion lead, as the battery was already converted to a BEC connector. Of course you can keep to Ultra-Micro Connectors and forget about the BEC connector. But as weight is less critical at the bow I prefer the larger BEC connectors.

The existing leads are cut about half way and two 130 cm 0,14mm2 leads are solderded in. Each soldered connecton is seperatly insulated with some cellotape (You can use some small shrink tubing if you prefer).

It might be possible that main leads thinner and lighter than 0,14mm2 would work too. However a test with very thin wire (I guess under 0,05mm2) gave a voltage drop that made the receiver cut the power far too early (integrated Lipo low voltage protection function).

Determining the lightest, suitable leads would need further testing. Obviously you should keep an eye on the quality of the connections to avoid to large a voltage drop over them too.

The battery leads follow the bottom seam of the balloon from stern to bow and are kept in place with some scarcely used cellotape. They actually lower the center of mass, keeping the blimp upright. 

Step 6: Trimming and Fins

The weight of blimp is trimmed to have it slowly sink to the floor when no power is applied. At the same time it has to be balanced to hang more or less horizontal. 

I first put the battery and some ballast putty at the bow, but after adding the fins I had to restore the balance and ended putting the battery out in front of the bow. Adding weight at the bow was not possible anymore as the lift capacity of the balloon was already reached. So bringing forward the center of mass meant moving forward the weight already present. The putty was replaced by a light plastic tube (as used with air filled balloons) to make that possible.

I first tested without fins and found the yaw (up-down rotation) of the blimp difficult to control. The pitch (left- right rotation) was wel suited for small spaces. So, as I had hardly had any buoyancy to spare, I only put on horizontal fins.

The fins are made out of 3 mm extrude polystyrene sheet. They are glued on a "foot" to be attached to the blimp with double sided tape. You can use special glue for polystyrene foam or use a tiny amount of regular superglue. Most superglue will "eat" polystyrene foam, but very small amounts do work on the extruded type.

Trimming of the radio control was basic: choosing the direction of the servo and trimming the neutral position.

Step 7: Lessons Learned

1. A single tail rotor in a directional setup is suited to fly in quite small spaces like a classroom.

2. Saving weight is absolutely critical at the back. I plan to try a lighter motor and maybe redo the balsa construction and hinges. This way the need to position the battery out of the bow, on a stick, should be avoided.

3. Only after that, I would test thinner, lighter battery leads. As these contribute more or less evenly to the weight they do not contribute directly to the balance, but it could help to make room for some ballast and/or some helium loss over time.


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    user

    We have a be nice policy.
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    47 Comments

    Sorry, I wish I could fix it, the balloon is no longer available. I will however adjust the text.

    The link to get the baloon Doesn't work. Can you Fix that please?

    Thanks!

    I think a brushless would be muuuch much better. And I think you should put the motor in the front, since it is a slow flyer, pulling principles would apply better

    1 reply

    The main factor at this time is the weight distribution. But as these days there are some brushless motors + ESC under 3g are available, I am planning to try it out one day.

    Indeed brushless motors are bound to give a better power/weight ratio.

    However putting the motor in front would defeat the purpose of building an indoor flyer that can hit a wall and continue flying without even crashing.

    As for pulling principles applying better? I learned that a push prop is slightly more efficient than a pulling prop. Is that not the case for a slow flyer? If so, I am curious why.

    Or do you mean it would be easier to control? Probably, but as long it can be controlled I prefer the more robust configuration of a motor at the stern.

    user

    Are you selling these blimps anywhere?

    1 reply

    No, I'm not.

    I might one day, when it is further developed.

    Hey masynmachien - Nice blimp!

    Couple questions for you. How much weight will it pick up?
    - I ask becuase i just picked up a DXG half HD video camera which weighs approx 5 ounces... thought it might be pretty cool to lift the video camera up and see how things look from the top so to speak. ;0)

    Lastly - Just out of curiousity really - have you tried running it slowly into a lite candle made to look like a wire tower or something, and filmed it with a high speed camera and played it back in slo-mo? Thought that might be pretty neat to see... the hindenburge effect kinda thing.

    I read you work with kids - so the last one might be a little much depending on the age group but - on your own - might be a pretty cool thing to try...  well i'd like to try it.

    I did check your link for the blimp it's in a launguage i don't under stand but i take it since the page you directed us to is pretty well blank with the exception of this:

    Webshop der Deutschen Zeppelin-Reederei GmbH
    Herzlichen Willkommen in unserem Webshop. Nehmen Sie sich Zeit und stöbern Sie in unseren Artikeln rund um den Zeppelin.

    Not sure what it means but - if i were to guess i'd say it says something abut the page being under construction - maybe - maybe not.

    can you translate this - or someone that understands the launguage translate what it means?

    Any other link for the balloon? In english or with an english page.

    thanx and again - real nice blimp!
    -chase -

    5 replies

    Thanks!

    The Zeppelin NT balloon lifts only about 20g (as mentionned). It belongs to the class of microblimps and so it not at all suited to carry a camera. i.

    Actually, 5 ounces is rather heavy for "livingroom" or "classroom" blimps. You would need one of the larger RC blimps as used in sports or exhibition halls.
    Check out http://www.blimpguys.com/ for example.

    As it is filled with helium, a flame would simply puncture the envelope and have it slowly deflate. So nothing spectacular to film.

    Now you mention it, although the Deutsche Zeppelin-Reederei site is doubled in English, the web shop seems not to be. It is not under construction, You simply come to the start of the German version inviting you to look around and check out the articles. I will add some guiding through, both here and to the Ible:

    klick on "Start Zeppelin Online Shop" or "Zeppelin-shop starten" in German. Then click on "Produktübersicht" and choose "Accessoires". Scrolling down quite a bit brings you to the balloon.

    Thanx - sorry i didn't see the lifting weight first time around.

    I looked at the blimpguys blinps thanx for the link btw
     - those are pretty big for what i was thinking. actually huge for what i was thiking of... suppose i could build one inbetween the size you made and those though. Shouldn't be too hard.

    Btw - i found this though i'm sure there are others even smaller these days.
    Wireless COLOR Pinhole Camera
    Perfect for Radio controlled cars,airplanes,boats, and spying.
    Weighs only 20 grams and sends
    COLOR images up to 100 meters

    and found a couple with 300 meter ranges.

    Helium - ah haa... the Zepplin was filled with Hydrogen - don't know why i was thinking helium... my bad. Though i suppose i could fill one with hydrogen... ;0)

    voting for you right after i post this as per request.
    and good luck with the contest - didn't know they had one going on.

    chase

    boxcambox_small.jpg

    Where id you find the colour pinhole camera?
    Can you supply a link? I looked but did nopt find anything I liked, (and could afford...).
    Thanks.

    BTW, masynmachien, cool dirigible!
    [Yes, I know the difference, but it just sounds more cool than saying
    aiship or blimp...]
    ;-)

    Hey avatar_i,

    The wireless pinhole video cameras can be fairly up there so i took a look around and you might like this one...

    Its Not wireless but could still be used from what i'm seeing and it's net weight is only 14grams.

    Some specs on this one are:

    1280*960 full real-time video
    Motion Detection
    8 million-pixel digital camera
    Web camera function
    High-quality record function
    Can record while charging
    Support 16GB Micro SD Card
    View range: 60 degree
    Recording resolution: 1280*960@30fps

    and like most digital stuff - prices go down as advancements go up.
    Here is a link to it... don't know if that is in your price range or not but take a look at it..

    HD Pinhole Video camera


    Have fun,
    chase

    whtscc.jpg

    Thank you very much for your vote.

    When choosing a size for your camera blimp project, bear in mind that the volume of a balloon, and therefore the lifting capacity changes with the scale factor raised to the power 3. That makes building small blimps a challenge. Luckily, modern miniaturisation comes to our help. When using an "RC toy" blimp 52" x 27" balloon (or an oversized 52" x 37" replacement from Plantraco), with RC gear of the latest generation you get some lift capacity to spare.

    This makes room for such a pinhole camera. However pay attention to the fact that while the Blimp RC gear works on a single Lipo cell (1s, 3.7 V), the wireless cameras most often need 5V or even more, so you will have to account for extra batteries. Again, nowadays you can find Lipo batteries weighing only couple of grams per cell, of course with limited capacity.

    user

    your welcome

    user

    Enjoyed the read. Thanks for sharing.

    1 reply

    Id be filling it with Hydrogen. Then you can use bigger motors and/or batterys :)

    1 reply

    Actually, the difference in lift capacity between hydrogen and helium is less than 10%. The use of hydrogen is clearly not worth the risk.