Scratch built Ornithopter

wingmanbunty · June 07, 2014, 07:13:26 PM

@Swapnil

sir i like your hard work and your design work is inspirational many

you deserve
your gearbox, flapping mechanism every effort is

Swapnil · June 07, 2014, 08:48:01 PM

Thank you so much for your encouraging words!

I do hope someone gets inspired and builds a much better ornithopter.

My ornithopter build has been completed and it flies really well. I'm posting pictures from 2 weeks ago to retain chronology. The huge gaps between postings are due to my really busy schedule (academics, personal projects etc).

The first flight was powered by a 3s 900mAH LiPo and felt kinda heavy. I'll soon try it with a 2s 850 mAH. I'll post a wing flap test and flight video after posting all the build details.

Anwar sir was right. I felt much more satisfaction while doing this project than I would have felt after receiving a cash prize.

P.S: I forgot to post the wing design last time. Pic attached. If anyone needs the sketchup files, please do ask.

Fw190 · June 19, 2014, 07:00:00 PM

Do post your flight videos Swapnil. Will be eagerly waiting for it; by the way whats the total flight weight of your ornithopter?

AnjanBabu · June 19, 2014, 09:12:00 PM

Interesting build, nicely done.
You could save a few grams by replacing the metals screws, nuts and spacers with nylons ones where ever you can.

Quote from: Swapnil on April 06, 2014, 08:05:36 AM
Gearbox and power system design:
1) Low kv BLDC with low gearing ratio vs. high kv BLDC with high gearing ratio.

Low KV, high gearing. Torque to RPM
High KV, low gearing. RPM to torque
Right?

Also, did you check this site? http://www.ornithopter.org/

good luck!

Swapnil · June 19, 2014, 09:27:26 PM

Quote from: Fw190 on June 19, 2014, 07:00:00 PM
Do post your flight videos Swapnil. Will be eagerly waiting for it; by the way whats the total flight weight of your ornithopter?

I'm eagerly waiting to post a flight video too, but it's too windy and rainy here right now. I'll be posting the rest of the build pics and test videos soon (possibly tomorrow).

The total weight is around 380 grams.

@AnjanBabu:

I did try nylon screws but they couldn't handle the huge forces generated by the system. All ornithopters I've seen of this size use mostly metal parts for holding everything together. Weight is not an issue any more. The final flapping mechanism is significantly smaller and lighter than the first one. The final weight is comparable to Sean Kinkade's 'Parkhawk'.

I didn't understand your query regarding kv rating and gearing ratio. The statement in the quote is quite straightforward.

AnjanBabu · June 20, 2014, 05:44:55 PM

For example, to obtain 10 RPM, you can either low gear a 20 RPM motor or high gear a 5 RPM motor.
Low gearing a low KV motor will further reduce the RPM and high gearing a high KV motor will further increase the RPM.
I was wondering what you were trying to do?

I'm dreaming about building an ornithopter since almost 7 years now.

arun.sreelakam · June 20, 2014, 08:55:18 PM

In the case of an ornithopter no one will think about increasing the rpm..
What we need is high torque and low rpm at the output..
Nice job man.. some suggetions
Go for a very very light wings you will know why when you attach the wings and make it flap for the first time..
All the best and waiting for the videos

Swapnil · June 20, 2014, 09:09:15 PM

@AnjanBabu:

There's a difference between 'high gearing' and 'gearing up'.

Ornithopters need a flapping frquency of 4 to 10 HZ (i.e 240 to 600 RPM) depending on the size. Given the high kv ratings of BLDC motors we need to 'gear down'. There are two ways this can be done. Using a low kv BLDC with low gearing down ratio or a high kv BLDC with high gearing down ratio.

So, when I say low or high gearing, it refers to the amount of gearing down. Most ornithopters this size use a high kv motor with a high gearing ratio. I used a low kv motor with a low gearing down ratio to get the required 5 Hz frequency.

What I failed to realize in my hurry was that high kv motors usually have a low current requirement. Hence, they need a smaller ESC and battery resulting in a much lower weight.

I'm considering redesigning the whole bird with a high kv motor at its heart seeing that the current flight characteristics aren't good enough.

Swapnil · June 20, 2014, 09:17:31 PM

@arun.sreelakam

The wings I made are really lightweight and strong considering their size. A 'parkhawk' or 'kestrel' of this size has a wing frame made of CF rods. So there's not much difference in weight. I guess mine are a bit lighter.

The first flapping test (done almost a month ago) was really amazing. It created huge gusts of wind. Felt like an eagle was pulling at my hand!

Devil_bhatt · February 23, 2015, 10:56:05 AM

Good job

ash · April 14, 2015, 08:04:43 PM

the wing designs is ok but i am worried about your gear box whats the weight ?

Swapnil · April 14, 2015, 08:22:09 PM

The gearbox was light for its size and worked fine for a few flights after which it gave up. Ornithopters like the 'parkhawk', upon which I based my design, use large gears. The gears in my gearbox were small and of poor-quality metal and hence kept getting chewed up.

If I were to do it all over again I'd go for a smaller gear box with fewer gears and a large gearing ratio. Also, I'd definitely go for a carbon fibre wing skeleton.

ash · April 14, 2015, 09:46:00 PM

great

can i see the video .............

Swapnil · April 14, 2015, 09:57:27 PM

I don't have any videos anymore. I deleted the whole project folder after I got bored with it. Ornithopters, much like multicopters, aren't much fun to fly; they just make a good science project. I've tried a lot of stuff but nothing trumps the joy and thrill of flying an airplane.

ash · April 14, 2015, 11:50:43 PM

Ohhhhhhhhhhhhh.........is it so ! hahahahhahhhahahah

Swapnil · April 15, 2015, 12:11:26 AM

Yeah, I even deleted the hovercraft and quadcopter folders for being too boring.
The ornithopter videos were online till 2 months ago. I removed them from there as well. Sad, you couldn't see them.

February 08, 2019, 11:16:36 PM

Can i get ur contact number swapnil because i need guidance for rc ornithopter project

Kantesh · February 08, 2019, 11:52:55 PM

Few months back I also made by can find carbon fibre so project discontinued

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Scratch built Ornithopter

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