Moderator Comment by Gary Mortimer on September 18, 2010 at 6:26am

Stig it keeps getting discussed, have a look here Perhaps there are not actually that many builders here!!

Comment by Stig A. Pedersen on September 18, 2010 at 6:34am

Thanks Gary

I don't know how i managed to miss that one.
Makes me feel just a little clueless.

I guess an apology is in order.

Kindest Regards.
/Stig.

Comment by tshado on September 18, 2010 at 6:44am

Hi Stig,

I followed the discussion referenced by Gary but I don't know what the results are.
I asked some time ago and I was told a group was working on it...
So your discussion is a good way to restart this topic which I think is a very interesting one

Best regards,
Jean-Claude

Comment by Curt Olson on September 18, 2010 at 6:46am

A couple thoughts ... the easystar is dirt cheap / simple. Could you come up with another design in the same ball park for price? It's a park flyer so it can operate from smaller fields. It's light and has a pusher prop so it would be hard to damage anything with it, even if you tried. And the ardupilot and probably other autopilots come with configurations setup ready to fly this airplane with no further tuning. That's a mountain of momentum to overcome if you are targeting entry level, hobby, diy folks who are looking to get up to speed as quickly and cheaply as possible.

You might consider a step up type airframe once people's needs out grow the easystar, but then it better be pretty good (in terms of flight performance, handling qualities, payload capability, price point, etc.) because there is a lot of competition out there. This is fun stuff so a lot of poeple don't mind working at a loss or just doing it for fun. I don't think a hobbyist working out of their garage could match the price point of one of the major ARF manufacturers, and really for the hobbyist, price is the primary distinguishing factor.

But those are just my own thoughts. If a dedicated individual or group wants to push something forward, I think that's great. A pinch of vision and a dash of dedication are often the key ingredients to a successful project.

Moderator Comment by Gary Mortimer on September 18, 2010 at 6:51am

No apology needed Stig, it needs revisiting. Curt is right though, pretty hard to beat an Easystar at the lower cost level. It brings with it reliable repeatable flight characteristics as well.

Comment by Stig A. Pedersen on September 18, 2010 at 7:27am

Thanks guys.

There's no doubt in my mind that out selling or "beating" the Easystar would be a tough one but it was never my intention to make money of it.
Basically my thought was the same as that of Sarel. You know.. Why isn't there an "open" Airframe to go with the open autopilot. That being one specifically designed for the task.

Running with the principals of "keep it simple" and "if it ain't broke don't fix it" maybe it's as simple as a low cost modified fibre glass or easy to build balsa version of the fuselage for the Easystar. I have read numerous posts here about people remodelling the fuselage of the Easystar in order to make the shoe fit.

I'm just throwing ideas around here but it's based on the very basic principle of .
a. Can you buy one. (well yes but their pretty expensive)
b. Would i buy or build one if it fit the bill. (yes i would)

What do you guys use?
Did you start out with an Easystar as well?
Would you have gone for the modified fuselage if you had to do it again?

3D Robotics Comment by Chris Anderson on September 18, 2010 at 7:45am

We've thought and talked about it a lot. Many other airframes have been considered, but it's really hard to beat the good old EZ.

We wanted to recommend something cheap, easy to build, easy to fly, widely available and used, robust, and with enough interior room out of the box.

Our thinking:

--Dynam HawkSky: just like the EZ, but has ailerons. This is a very good choice, but is not quite as robust as the EZ and is sometimes out of stock. Doesn't have the range of mod options and experience as the EZ
--Various other EZ clones, like the AXN Floater: Servos are inside the canopy, eliminating most of the interior room
--Skywalker: Great UAV platform, but bigger and harder to build than the EZ. Too much for beginners.
--Balsa trainers like the NexStar EP: Not robust enough for beginners
--Other plane that we like, from the Skyfun delta to the Twinstar to flying wings and various powered gliders, suffer from being too hot for beginners, or too hard to build, or not perfect for UAV use.

Mind you the EZ is not perfect, by an means. You have to upgrade the motor and increase the rudder, so it does require some modding. If the Dynam HawkSky didn't come with a terrible FM radio that you have to throw away (which makes me feel guilty), I'd probably be ready to recommend it instead. It's really RTF and although the plastic power pylon is a bit noisy it at least comes with a brushless motor out of the box.

Comment by Curt Olson on September 18, 2010 at 8:08am

Hi Stig, I hope you don't mind me jumping in here with my opinions and questions ... I'm just speaking from my own perspective (and I've discovered at times that my perspective is not always close to the main stream, and now I'm old enough to not care.) :-)

Right now I'm doing most of my development work with a Senior Telemaster. I like that it's a good load hauler. I like it's gentle and forgiving flight characteristics. Most of the time (when I'm developing and testing) I like it's slow flying speeds. I'm not in love with it's high dihedral wing and the fact that it wiggles and bobbles and reacts to every little gust and burble and any little rudder input results in a lot of roll and any little aileron input results in a lot of adverse yaw and dutch roll. I'd like to have an airplane that is similarly gentle, but more neutrally stable so hands off it flies more like it's on rails and with gentle control inputs there isn't a lot of cross coupling between axes. I'm not a super expert pilot, but I'm not a novice either, so that affects my choices and what I am looking for in an airframe.

So presented with a new potential airframe here are some things that I would immediately look at:

- flight characteristics (gentle, forgiving, predictable) A more generic term would be "handling qualities". I also want solid and stable in the air ... reacting less to gusts and turbulence rather than more (a knock against telemaster or trainer style airframes.)
- payload (can it easily/safely carry the size and weight that I am used to carrying?)
- payload flexibility: how easy is to access my avionics and batteries at the field. Is there room to get my fat hand in and fiddle? Do I have to disassemble the whole airplane to get at the avionics or change batteries in the field?
- what about endurance? I've become accustom to 20-30 minute flights in my telemaster.
- cost of course is an issue (or assembly & construction time as well.)
- field logistics ... how much hassle is it to assemble the airframe at the field? What support equipment is needed? This is probably where the easystar has everyone beat. The telemaster has things like load-struts that need to be attached in addition to bolting the wing on ... and needs to be fully dissembled to fit in most people's vehicle.

I don't think it's easy to design the perfect UAV (at least not if I'm the target audience.) I want stable and predictable flying qualities. I want gentle and forgiving flying qualities. I want easy access at the field to my batteries and avionics without needing to disassemble the aircraft to get to them. I want minimal assembly and disassembly time at the field. I want minimal support equipment. And I want to be able to haul a pretty big load for a long time. And I'm accustom to hobby ARF price points of maybe $200-300 for a telemaster class airframe.

That's just me ... but when you think about designing for good handling qualities, there's a lot of RC design and building and flying experience required to achieve that. Mix in a need for a large and accessible payload area. Add a desire to minimize field assembly/disassembly time and minimize support logistics (fuel management, starters, launcher ... and add cost as another real world factor ... it's not a super simple task to come up with a new airframe that beats the existing selection.

More power to you if you can do it, but I think you'll be in it for a lot of design revisions, building prototype after prototype, changing wings, changing tail, changing power, changing fuselage, etc. It's wonderful stuff if that's what you are into, but unless you are chief airframe designer for a place like "Great Planes" or "Sig" or one of the other big guys and have a ton of experience and know what works or doesn't, you probably aren't going to hit the sweet spot on your first try by accident. But you might hit some good things on your first try and hopefully that will give you motivation to push forward and keep tuning and refining.

But I think whatever you do, realize the time and cost is going to greatly exceed what is available off the shelf, so you should be thinking about what specific improvements are forcing you into a new airframe design process and what specifically you want to accomplish and what you want to see at that end that is different from what is commercially available.

Comment by Stig A. Pedersen on September 18, 2010 at 8:37am

Curt i applaud you jumping in here. That was my whole point.
Getting input from you guys on this is invaluable although i'm beginning to see a trend here :)

I never expected it to be easy but then again i'm not sure i completely grasped the scale of what i'm/we're up against.

As you pointed out it takes a tremendous amount of experience of which i have very little but on the other hand i'm a firm believer of being able to do what ever you put you mind to.

The whole design, prototyping and re prototyping thing however doesn't put me off. I have another hobby which is autonomous robot sumo wrestling so i'm kinda used to that :)

Curt: What kind of weight are you hauling around for 30 minutes?

Once again. Thanks for the input all of you i really appreciate it.

Comment by John_K on September 18, 2010 at 8:55am

On-the-wings-of-a-Star?
es-my-0.02

Star-wings-are-sweet
Radian-wings-are-sweeter…

http://www.rcgroups.com/forums/member.php?s=8079cda0db603e6b2fead42...

http://www.rcgroups.com/forums/showthread.php?t=1300632

Fine-tuning-V.2_7_1-as-we-type…
John

Pardon_”-“_
spacebarbitthedust

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