Build Log miniECHO - world's smallest 3D heli - PREORDER list is open

[U.S.U.L]

Original post:
"Hello

This is the project i am working on sice last 3 days. I thought it would be cool to make a smaller version of ECHO. The plan was simple - scale CAD drawings, remove few bits out of it add few others and put it together

Most parts are made from thin 0.65mm carbon fiber laminate and plywood. Tail is driven by shaft, CP bell-hiller rotorhead, CCPM 120 swash, most of moving parts on ball bearings and fully servicable mechanics.

Target AUW weight is max 55g, with 3s180mAh battery pack, 9g brushless motor, custom 2g digital servos and other lightened components.

I hope to maiden it in few weeks and then try some acro.

I also realized that this is the first time when ECHO leaves my PC/visuals and exists in reality That makes me very very happy! "

UPDATE 10.06.2009

There has been some major changes in frame and tail design:
Completely new frame/tail mechanics design, some small changes in rotorhead, longer tailboom.
I wanted to keep everything as simple as possible.

Weight is reduced to 61g, more power, better CG location, more stability and agility.

I personally think it is as good as it only can be


» Technical specification:

º all up weight 55-65g (depending on used electronics)

º main blade lenght 120-145mm

º height 90mm

º maingear 48T

º gear ratio 1:4.80:3.55 / 1:4.36:3.55

º recommended battery pack 2s1p 240-350mAh

» Features:

º fully 3D capable collective pitch rotorhead

º shaft driven tail rotor

º precision tail rotor pitch mechanism

º 17 ball bearings for reduced friction

º bell-hiller mixing

º carbon fiber/glass fiber construction

º super light, strong and durable frame

º brushless motor

º direct 120* CCPM system swashplate


This is the project's website http://www.revoflite.com/miniecho.html


Before You decide to order miniECHO:

Be advised that it comes as a KIT. This means You need to posess at least moderate manual skills and some experience to complete the build properly. Although the part count is low, most of them are of very small size and need to be put together with precision and patience in order to obtain good and vibe free flying characteristics.
I highly recommend this kit to those of You who already own few helis or built any RC models before

For now the preorder list i closed. I will open it again once i got first several kits completed.

Full price is 240USD.

I decided to take preorders in order to gain some founds needed to start production.

Preorder price is 100USD and the remaining 140USD will be billed to You when the kit is ready to send(more info below).

The kit will contain bare bone miniECHO helicopter mechanics, brushless motor, ESC and blades.
To complete the build You will need:
- at least 6ch Tx with 6ch Rx under 2g weight(AR6300 suggested)
- 3x 3g precise servo for swash control(HM-4G3-Z-32)
- 1x fast and precise servo for tail control(preferably LSX 065HS)
- under 3g piezo gyro, HH function highly recommended(most of 10-7g gyros can be easily lightened to 2-3g)
- li-poly 2s 240-350mAh battery pack


Let me know if You have any questions.

[small.planes]

THat is so cool
Kudos USUL

Dave

[frac]

you do beautiful work USUL

can you describe the motor and digi servos a bit more?

frac

[cyclone2008]

I'll take one. thanks lol

[Gino CP]

Wow. Your CNC is up and running. Looking forward to its maiden flight.

[axelen]

looks soooo cute !
can't wait to see it in action

Cheers!

[U.S.U.L]

Thanks for Your kind words.

can you describe the motor and digi servos a bit more?

The motor is a cheap "10g outrunner" from HC with metal shaft removed and replaced by CF one, plus some weight removed.
Servos are made by Arced and they advertise them as the lightes digital servos. In fact each weights little over 4 grams before modifying.

Now i'm busy with tail which as some of You probably know is "secret" and unfortunately i won't be able to show any details of it.

[billm555]

Wow, very nice.

Bill

[Shogo]

Beautiful piece of work. If you can complete the project and go inverted with your heli, it will definitely be a museum piece.

[village_idiot]

I had some of those Arced servos, all 4 were garbage and went back for a return. Mine did not move smoothly whether under load or no load. Tried with 4 Nimh cells and 5 cells, they get really hot with 5 cells so I wouldn't recommend anything more than 5 volts.

How are the ones that you have?

Also did you think about using one of the 5 gram outrunner motors? Just wondering if they would have enough power to use in this tiny little heli. Spektrum AR6300 receiver gets down to 1.3grams with the connectors removed (just in case you need a receiver), might be able to get another .1 off if you change the antenna to a smaller guage wire.

Otherwise that frame looks really cool. Might be nice to kit it up and sell it.

[U.S.U.L]

They are fine for their price, maybe not so smooth as bigger digitals but still much better than BA2.5. I think the cause of all problems with them is a very tight pot.

Here is my 25g heli powered by 5g outrunner(5.3g to 4.7g after mods) and ar6100 lightened to 1.3g - http://www.rcgroups.com/forums/showthread.php?t=798420

As for selling it. Funny, but there may be a possibility that i start to produce this one faster than it's larger brother

[megamatt]

usul,
i actually dont know what to say,there is no stoping you!you build better quality stuff than i could buy!will you be seling a few?if so put me down for one.

[village_idiot]

Not to get too far off the track, but do you think the new version 2 Toki muscle wire servos would be fast enough for the cyclic? They are only 1 gram with the wire and connector, and very small.

Maybe I'll have to try the Arced again, if I had had just 1 of the servos behave properly I would have worked to find out how to fix the others, could have saved 2 grams per servo over what I am sticking in my EP100 right now. That's a lot of weight in the end.

[megamatt]

any updates on mini echo yet?

[U.S.U.L]

Originally Posted by village_idiot

Not to get too far off the track, but do you think the new version 2 Toki muscle wire servos would be fast enough for the cyclic? They are only 1 gram with the wire and connector, and very small.

I think they are ok but they are a little problematic for very small helis like this because of their lenght(38mm), they simply dont fit into the frame.

The machanics is complete now, i will post some picture tomorrow.