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Old Aug 13, 2010, 01:17 PM
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Hungary
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Thanks to everyone!

I want to build more rubber band model. They could be very simple and cheap. I don't need big space to fly it, I don't have to worry about the electronics... And I could bring one with me when I am not at home. So it has advantages.

I also want to improve the "engine" and build more detailed models, may be scale ones too.

Gabriel
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Old Aug 15, 2010, 02:16 AM
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hoverman's Avatar
Netherlands
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Well, looking forward to more models & Designs then!

I am home again, think I can start building next week, the first heliferry model. It's going to use a Honey Bee King 3 for the helicopter part, rest of the craft will be tempex, balsa and foamboard. It's going to be small, I don't think this will improve the handling, but it surely reduces the costs, especially those of the helicopter

Marijn
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Old Aug 15, 2010, 04:12 PM
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I always looking for special and out of ordinary in everything. IMHO the heliferry will be the most special of every model I have ever seen. So I am looking forward for it.

I accidentally broke my rubber band WIG I broke off its nose during winding. It was made of balsa (I used a small Revell balsa model). So I made a new 'fuselage' out of bamboo. It is very strong, and light enough.
I found a better rubber band so now it is able to fly more than 20 meters.
I also made a primitive tool for an accu-drill to wind up the rubber band :P

Gabriel
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Old Aug 17, 2010, 01:01 PM
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Well, looking forward to more models then

I'll post some more drawings of the Heliferry later this evening, and some construction photos, I finally got started today.

Marijn
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Old Aug 17, 2010, 01:07 PM
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Joined Aug 2003
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Looking forward to the Heliferry, should be interest experimenting.

They have all kinds of cheap helis at Hobbyking if you havent looked there yet. $30 for a heli, now thats cheap.

Dont forget to get your sea monster working! Love to see that thing in action.
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Old Aug 17, 2010, 01:47 PM
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Hey Silenthunter, You're right, those HK450's really are cheap. I first intended to go for one of those, but then decided to place a topic on a Dutch forum, to ask for any old & crashed 450 helicopters(should be a lot)

So, I got a free Honey bee CP2 wreck(nice haha) and A Honey bee King 3 with half a Honey bee Belt CP, and an extra rotor head, brushless engine and ESC, new rotorblades, for about 60 euro's. Not such a bad deal either

Anyway, I scanned in some drawings, to show how the design changed, most of them are simple sketches so don't mind the bad drawing quality.















Thought you guy's might be interested.
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Old Aug 17, 2010, 01:57 PM
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And here the photo's of the progress of today, started out with carving and sanding of the center hull. It is of a wavepiercing design, and has a very sharp bow.


Cut the slot for the wings:




And with the wing added, and a trial fit of the helicopter:




First thought...This is never gonna work Second thought...still this is never gonna work Haha no, just kiddin.

Important to know is that the rotor doesn't have to lift the entire craft out of the water, especially not in hover. It accelerates for a short distance, then uses the rotor to unstick, and than accelerates further. A rotor also provides more overall lift, when moving forward.

Greetz,

Marijn
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Old Aug 17, 2010, 06:10 PM
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Hungary
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Wow. You build it really fast! It will be an insane model.
Keep up the good work!

I built two more rubber band powered wig model, but they didn't want to work :/
Than I ran out of "WIG ideas", so I decided to build a rotor kite/gyroglider for windy days. I didn't try it out yet.

Gabriel
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Old Aug 18, 2010, 02:25 PM
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Could you post some pictures of your kite? You could try to build a twin rubber band model btw, a small scale KM for example.

Day 2:

I started the build by cutting of a part of the bottomskin of the hull, to increase the angle of attack of the main wing, and reduce the trailing edge gap
Result:


Then I started on the upper side of the boat hull, the bottom part of the electronics bay:


Then, the sideplates of the outboard wings:


The sponsons:



Tadaaa:




Final weight(much more then I had hoped


Marijn
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Old Aug 18, 2010, 05:31 PM
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Nice!

Just a question: Since I had to check on how gyros work, as far as I know helicopter rotors don't really work as autogyro rotors. So won't it be a problem during ground effect flight?

My gyro kite... it has only flat airfoil rotor (which are spins counter than real gyro rotors do since it has no "normal" airfoil), so it is a very primitive kind. And I still don't know if it's working since there wasn't enough wind today. I could post photos only few days later.
But here are some photos of gyros in the aviation and aerospace museum in Paris : http://s241.photobucket.com/albums/f...sGbr/autogyro/

Autogyros are also very interesting aircrafts, and more complex than I imagined.. so I have to learn more about them.

Gabriel
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Old Aug 19, 2010, 09:08 AM
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Gabriel, there is a world of difference between an autogyro and a helicopter, and one thing I found out till now, is that although they are the "predecessor" of the helicopter, they are in no way simpler

Most people don't even get why it is possible that a rotor windmills, allthough the blades have no negative angle of attack(maybe even a bit positive), allthough it is a quite simple principle. Then there are things like coning, which is much more complicated to fully understand.

What I don't get is why it is nearly impossible to build a well controlled helicopter without a swashplate(but with a pivotting rotor), allthough autogyro's work just fine with them!

Anyway, about your question, the real heliferry would use the Cartercopter concept, which is a cross between an airplane and a prerotated autogyro. The rotor is prerotated before TO, then with a bit of forward speed, positive pitch is applied, the craft lifts off, accelerates forward, and pitch is brought to a position of where the rotor keeps on turning nicely due too the wind. Once a higher speed is reached, the pitch is reduced further, till the rotor isn't messing with the aircraft anymore.

Our Take off will be as much as possible like this system, the rotor is prerotated and the craft accelerates forward, than positive pitch is applied, the craft accelerates further and pitch is reduced to zero.

As you can see, it is very much alike, the only thing is that the rotor doesn't windmill like an autogyro rotor after TO, but it is kept on rpm by it's own motor.

Why? well it would have been much more complicated if we would have used an autogyro model with prerotator.

Anyway, the progress of this morning:

I started on the buildup ontop of the craft. It took me quite some time to come up with a design which was right, here it is:


It is quite high, but it needs to cover the helicopter frame, which in turn needs to be mounted high, so the rotor isn't located too low over the wing.

The Hull is devided in three sections, a forward accu/ESC bay, a middel helicopter frame bay, and a rear bay for the propulsion and reciever. I made it like this to reduce the chance of wetting all the electronics at once during a crash.
Here you can see the permanent covers, all the open spaces are going to be removable hatches.


I added a triplex platform inside the hull, for the frame to be mounted on, and then started on the fins&stabiliser.

I tried several materials for the fins, but decided to go for plywood. It is not as heavy as I thought, and much stiffer than balsa and foamboard.


The stabiliser is sanded down to Clark Y, from a balsa strip, and is located on two pivots, to make it possible to change it's AoA during trials:


Alltogether:






This is where you get one of those moments like "what the hell am I building"

Marijn
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Old Aug 19, 2010, 09:56 AM
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Quote:
Originally Posted by hoverman View Post
This is where you get one of those moments like "what the hell am I building"

Marijn
i think the same

I am impressed how fast you work, I am still waiting for the rain to stop ( 4 days) and I have not managed to properly secure the engine to keep it loose.

good luck.

Jorge.
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Old Aug 19, 2010, 12:41 PM
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Hey Jorge, are you still repairing the Aircat or are you building a new model?

Some more updates, I think..I finished the airframe, at least it doesn't seem to miss anything.

I added two rudders with horns, added two plywood fins for the motor mount and then started to build the covers for the hull.




The hatch where the rotor penetrates through the hull is made of two parts, so I can remove the helicopterframe for maintenance or repairs

Tadaa:





It actually looks nice

Marijn
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Old Aug 19, 2010, 01:22 PM
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first, repair it and make a final test, if it works it will improve, my next model I'm thinking of something like airfisch 8.

Jorge.
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Old Aug 19, 2010, 06:46 PM
BEOWULF
North vancouver, B.C. Canada
Joined Apr 2008
18,575 Posts
wow Hoverman that looks really cool and your drawings are out of this world professional

can't wait till the maiden video
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