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Old Jan 08, 2007, 05:46 PM
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Index 2

EDIT:
It's a long time since this post and I thought I'd come back to the start and insert a links to the more recent versions of the Index series of designs. The Index 2.2 plans are located at post #130 and the plan for the Index 3 is located at post #347 for anyone who wants to skip right there.

Now back to the original contents of this post>

______________________________________



It's time for another one!


I was very happy with my Index design but now I want to try something smaller so I'm going from 900mm (35.4") span down to 750mm (29.5").
The Index 2 is based on the original design proportions but there are several small changes.

I think the Index had a little too much side area ahead of the CG making it slightly too neutral in yaw for my liking so I'm shortening the nose a noticable amount. All of the other changes are very small but add up to a planform which looks quite a bit different.
Index 2 will have less LE sweep but maintain the unswept aileron hingeline so the ailerons will have more taper. I've also reshaped the wingtips and tailplane.
The fuselage profile is a massaged version of the original. As I mentioned the nose is shorter but aside from that it's all small changes. The rudder extends a little further aft and doesn't protrude as far beneath the tailplane on the new version. It'll also have an aerodynamic counterbalance.

I haven't cut depron yet so it's possible I'll make one or two more changes but I think the drawing below is going to be pretty close. I plan to get started later in the week.

I'll post plans once they're finalised.

Aidan
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Last edited by Aio_1; Nov 03, 2010 at 04:05 PM. Reason: Added link to post containing the current plans
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Old Jan 10, 2007, 11:44 PM
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I guess you are hard on your planes… it’s looking a little black & blue.
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Old Jan 15, 2007, 06:54 AM
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I got this cut out and painted over the weekend. I'm pretty happy with the result. I'll post pictures later today.(my net connection was down last night)

It's very similar to the drawing attached to post#1, I just made a couple of very small tweaks. Weight of the depron parts was 35g before paint and it's up to 37g after painting. This doesn't include the depron braces or leading edge doublers which I'm considering adding.

I'm currently trying to decide how to brace the wings and fuselage. I was planning to use depron bracing (2 diagonal strips the length of the fuselage between the vertical and horizontal fuselage members above the wing as per the F3A shocky and Clik among others) for the fuselage and either carbon rod or thread for the wing. I haven't made a definite decision yet.

What diameter carbon rod is sufficient for bracing the wing? I think 1mm is the smallest I have. I must check if I have enough.

Aidan
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Old Jan 15, 2007, 01:00 PM
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Here's the pics.
Next I've to decide how to brace it. Any suggestions are welcome - although I might not follow them .

The radio and power system will be:

11g motor: Flyware MacroREX220/3/3200
20g cells: Hyperion 300VX litestorm
5g servos: Ripmax SD100 (same as Dymond 4.7)
6g ESC: CC Phoenix10
5g receiver: ACT Pico 4
~2g prop: GWS HD 7x3.5

That's about 60g

So I'm on target for 97g not including landing gear, bracing, motor mounting plate, hinge tape and control linkages. I reckon AUW should be under 120g if I'm carefull.

Aidan
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Old Jan 15, 2007, 01:18 PM
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Looking good!
Of course it's a matter of preference, but I prefer the depron fuse stiffeners and carbon rod for the wing (which doubles as landing gear). The thread is extremely light for the wings, but tends to snag while handling.
-Scott
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Old Jan 15, 2007, 01:24 PM
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I would personally try the spider fishing line like Devin.
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Old Jan 15, 2007, 01:55 PM
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Spiderwire for the fuselage, or box it in.
As for the wings....sparless Vecht X bracing like this....
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Old Jan 15, 2007, 02:01 PM
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Hi Aidan, looks great!

What I did was copy the Bling Bling job by the Van Der Vecht's, using 1mm cf.
I threw a full throttle "wall" at it, and it held without incident. Solid! 120g as well.
It's on the last page of the BBV3 thread still.
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Old Jan 19, 2007, 06:00 AM
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I may have to retire aged 31!
Work just keeps getting in the way of my plane building and this one looks like it will have to be a rush job tonight and tomorrow if I'm to give it a maiden on Sunday.
I don't have as much small diameter carbon as I thought so I may have to abandon the carbon bracing and stick with thread and depron unless I can get hold of some tomorrow. I was going to use 1mm for the bracing and 1.5mm for the undercarriage but it seems I only have a little 1.2mm and a couple of lengths of 2mm left. Has anyone tried 1.2mm carbon for undercarriage legs? It's a little flexible but I think it might just be enough for <120g planes. What do you think, should I stick to 1.5mm and 2mm for UC?
There'll definitely be some progress to report over the weekend....honestly

Aidan
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Old Jan 21, 2007, 02:42 PM
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Quote:
Originally Posted by Aio_1
......There'll definitely be some progress to report over the weekend....honestly....
Okay, I lied.

It turns out I hadn't enough carbon rod for the bracing and I hadn't enough kevlar thread either.
I called the LHS on Saturady morning and he assured me he had either 1mm or 1.2mm carbon in stock. I drove across town to purchase some and it turnd out all he had was 1.5mm and bigger. I was not impressed. The idiot had wasted half my Saturday by the time I'd gotten home through bad traffic .

Anyway I decided to hold off until I get the correct materials and just flew the Index 1 today. I'll order some more thread and carbon but it'll be at least a couple of weeks before I get more indoor time.

Aidan
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Old Feb 17, 2007, 11:58 AM
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Okay then, back in action!
I had to get my carbon and thread by mail order and they arrived yesterday. I must recommend www.Indoorflyer.co.uk . Nice guy, great stuff and decent prices. I got a couple of Fullriver 250 cells too.

I hope to get the bracing done today or tomorrow. It's not a major job but I had a tough week at work and can't seem to resist the urge to just sit and relax for the weekend!

Aidan
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Old Oct 14, 2007, 05:19 PM
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8 months later the story resumes!

I like to take a quick break between phases of my builds.
This time I decided to take 8 months between painting and assembling.

I shelved this at the end of last winter's indoor season with the intention of finishing it off as soon as I had a few outdoor planes taken care of but I never got back to it. Now the new season is upon us and my first opportunity to use a gym is next Saturday. I got back to work this weekend so I'll have the Index 2 ready.

Done:
Bracing done (unless I add a little to the upper fuselage)
Undercarriage on
Servos installed
Ailerons and elevator hinged and linkages done

Still to do:
Glue on the upper fuselage profile
Hinge and hook up the rudder
Mount the motor
Install the ESC and receiver
Find the battery location for balance and put in a strap

Everything that remains is straight forward except the motor mount. I haven't decided how to do that yet.

Aidan
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Old Oct 14, 2007, 05:27 PM
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Looks good Aio_1, it is a very clean build.
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Old Oct 21, 2007, 05:14 AM
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Success!

The Index 2 has taken to the air.
In fact two of them have, many, many times and I'm absolutely delighted with the result.

It flies exactly as intended and even better than expected.

I got mine finished in a bit of a hurry yesterday morning and headed off to the first indoor meet of the season. My father liked the look of mine when he saw it last week and decided to build one too (he even copied my paint scheme ).

His finished up at 119g and mine is 124g.
Both have the same servos, motors and cells but mine has a small piece of tail weight which is responsible for most of the difference. I can move my receiver to get rid of that I think.

I had the best day of indoor flying I ever have. We were at the gym for over 5 hours and I spend a good proportion of that flying the Index 2! I've 4 packs for this plane and there were 3 on charge at any given time! I must have clocked up at least 15 flights and maybe 20. I've never been so comfortable with a plane. After only 2 or 3 flights with this I was more confident with it than any other indoor plane I've flown.


Flying

I couldn't be happier with the flying characteristics. It's incredibly easy to fly. Very crisp and precise with no significant coupling that I could detect.

At 124g mine is nice and slow. It does pick up speed when you open the throttle or on down lines. That can be prevented by adding air brakes if you want a more single speed plane but I don't think it's necessary. My policy has been to get the basic airframe right before adding any aerodynamic devices. I really like the speed range it has at the moment but retro-fitting airbrakes is simple and I plan to do some experimenting with them on this plane in the near future.

The roll rate is nice and fast and beautifully axial. The good roll rate is partly due to the relatively small span (750mm). I was considering counterbalanced ailerons but they're definitely not needed (I might try them anyway on my next one just to see what difference they make).

One of the biggest differences between this and the Index 1 is the yaw control. The rudder is more powerful and there is little or no coupling. It generally feels crisper. At full rudder deflection (about 45 degrees) it'll do ridiculously small flat turns (maybe 5ft in diameter). It's not really an F3P manoeuver but it looks great and gets a good laugh. With the CG where I had it you only need to breathe on the rudder to maintain knife edge and there's enough side area to fly knife edge at very low speed.

Elevator is plenty powerful enough for everything I tried. Again it has a nice crisp feel to it. Responsive without being twitchy.


Comparison with the Index 1

The Index 2 is even easier to fly and has a nicer feel in the air. My suspicions about Index 1 side area are confirmed. The Index 2 turns much more cleanly and predictably.

Hovering and harriers were ridiculously easy with the Index 1 which I loved. I wasn't sure if some of the changes on the new version might compromise those particular manoeuvers but in fact it's even easier to hover and I think the harrier is about the same.


Conclusion

As I'm sure you can tell I'm delighted with how this turned out.
A couple of other pilots had a go with the Index 2 yesterday and were very impressed (good for my ego ). Both of them are now planning to build one. I'm also very happy with the appearance. It looks "right" to me in the air.


Plan and pictures?

I'll add some more detail to the plan and post it tonight or tomorrow. I'll post the plan here and put a link to it in the F3P Plans Sticky. I've taken a few pictures which I'll post later today.


Aidan
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Old Oct 21, 2007, 06:05 AM
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Nice report, Aidan! Top marks. Will build one myself when you post plans.
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