Ah right. I'm familiar with coupling just wasn't sure what you meant by the phrase "does not couple out". I follow you now.

I didn't have the scaled up plan I drew for myself on my home PC. It's on my work computer and I forgot to e-mail it to myself. I've just done the attached plan in a hurry but it should be identical to mine except the depron thickness is drawn as 3.24mm instead of 3mm (it's 11:30pm here and I've got to be up at 6:30 so no time to tidy up the plan. It's pretty much just the original scaled to 810mm span and turned into a pdf).

Aidan

There does not seem to be a plan attached!

Hope you are still awake!

oops....there you go!

I think I'll call the 810mm version the Index 2.1 instead of refering to them as the 750mm version and the 810mm version.

Aidan

Thanks mate!

A full build report coming up!

I now have a 15g hacker to put on it

Originally Posted by Hexosex

Thanks mate!

A full build report coming up!

I now have a 15g hacker to put on it

You'll have it in the air before I have mine finished. Work christmas party is on Saturday night so I won't get much done this weekend!
It'll be useful to know how it flies with that power system because I'm considering flying it in a competition next Friday and I won't have had a chance to test it first!

Using a GWS 7x3.5 prop?

Aidan

8x4.3 prop is what i am going for, but your smaller prop will be lighter. I tend to push this amp stuff unless i am at WOT all the time...

With the 8x4.3 you will get the thrust you want when you want it but you wont need it most of the time. Power management is a must though!

I'd expect the 8x4.3 to be a lot too much for that motor!
Have you tried it already?

My plan was to try the GWS 7x3.5HD and move to 8x4HD if I wanted more power. The 8x4.3 slowfly prop draws a LOT more current than the 8x4HD.
I look forward to hearing how you get on.

Aidan

Where in the UK can i buy these hyper drive props? I cant seem to find a supplier on google!

I'd go to http://robotbirds.com/catalog/index.php?cPath=42_44
I'm not sure if the 8x4 is a HD ("hyperdrive") or DD ("direct drive") but whichever of those GWS ranges have an 8x4 - that's the one.

Aidan

Well thanks for all the advice so far…

I thought about it back-and-forth Tuesday night and I’ll go ahead and use pull-pull setups for both elevator and rudder. I may as well do this right. Wed night I made a sheet of fiberglass to make the horns, motor mount, and tail skid from. Last night I cut the horns, skid and motor mount as well as installed the servos. Tonight I should be able to pretty much finish assembly. I’m kicking around a grass-compatible landing skid idea, since I’m concerned that grass may catch the delicate CF supports and break them or tear them off.

I realize that I may be setting myself up for failure by trying to fly outside but worst-case, I’ll just build a tougher foam/balsa hybrid that can take some more abuse even if it ends up weighing a few more ounces and can’t go vertical. The Index 2 is only a few inches smaller than a balsa profile plane I have and it weighs 17 oz and flies fine. Or maybe I should build one with the CF bracing on top to keep it out of harm’s reach. That Park 250 should haul around an 8oz plane just fine. Remember your “sport” plane about 15 years ago? I had a GP Super Sportster that flew like a sack of rocks with wings compared to models today and I used to have a blast with it! If my quick math is right, my Index 2 will have a wing loading of about 0.027 oz/sqin and the SS was around 5.5 times that at around 0.15 oz/sqin...

I’ll post some pics tonight and hopefully some of the completed plane.

Originally Posted by Aio_1

I'd go to http://robotbirds.com/catalog/index.php?cPath=42_44
I'm not sure if the 8x4 is a HD ("hyperdrive") or DD ("direct drive") but whichever of those GWS ranges have an 8x4 - that's the one.

Aidan

Cheers! I'll get some props on order!

I've got the plan printed out so next step is to start the build! I'll be cutting out in the morning

Well, here is my completed Index 2. It's still windy and overcast in Houston this morning, so I think I'll play it safe and stay grounded and keep it in my truck just in case the weather is nice coming home (or going to?) work this week.

It came out to 152g (5.36 oz) and was a bit heavier than I wanted. I could probably have shed 15g or more with lighter batteries, ESC, servos, lighter servo hardware, and using depron instead of cellfoam 88 which I understand is a very slight amount heavier. Overall I'm happy with it for a first attempt at a foamie. The next one will have a target of 5 oz or less.

I'll let you guys know how it flies when I get the chance... Thanks to Aidan for the nice design.

Very nice job Pablo. It looks like a very neat build.
I hope you're happy with how it flies.

I think for outdoors it will fly perfectly well at 152g. I'd expect it to be a little fast for F3P style indoor aerobatics at that weight but still lots of fun. The original was 750mm span mostly because the motor I was using (11g Flyware MicroREX220-3) would probably be marginal with a plane over 130g and I wanted to be sure I could keep it light enough. Using slightly more powerful motors like the Hacker A10-15s or Park 250 I think you'd be okay at sizes up to about 850mm. I'm aiming to keep my F3P style planes at or below a wing loading of 10g/sqdm. The 750mm version has about 12.6sqdm of area. The original came in just a fraction under the target at a weight of 124g (124/12.6 = 9.84).
If you intend to fly indoors, have slightly heavy gear and want really slow flight I'd suggest scaling up the plane to suit the equipment. However it should fly well even well over the target weight on the plans if you're not too bothered about keeping it very slow.

Aidan

Good stuff Pablo! I like the art work as well, simple and nice. I don't give mine that much effort as you can see below!

AUW of my the index 2.1 is 140g, 5g more as I've used some larger servos for the tail feathers. I've also gone for a single leading edge carbon strip and fishing line bracing as i cant find any kevlar near by! Its still very stiff though. This combination normally lasts a week or two of punishment!

Maiden on Wednesday!

I changed my battery mount, worked out very well. This is also how I store my planes. Just thought id share.