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Old Sep 06, 2010, 04:53 AM
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UK, North Down, Bangor
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Building a FPV platform as first scratch build.

I'm thinking this over. Was going to do a little 3D plane, but figured I enjoy video-graphy more.

Before I look at plans I want to set a few requirements of the design, specializing towards FPV.

1. Must be able to carry:
* FPV cam
* Video Tx
* Video/Tx Battery, Cables, Mount
* GoPro Hero in plastic hard case.
... in addition to it's own flight pack.
Circa, what, 400g / 1lb?

2. Must be a pusher or pusher twin.
3. Must be slow
4. Must be generally stable.
5. Must be adequately powered for gaining altitude.
6. Be forgiving.

I don't need aerobatics, speed or even agility.

From the little I know about aircraft design the above requirements make me think:

High wing = stability and forgiveness.
Broad slightly dihedral flat bottomed, 'plank' wing with layered foam airfoil = low wing loading, powerful lift and slow flight speed.

Going back to weight, I was thinking,

if the gear to carry may weigh 400g
... and the plane will surely weigh that itself (call it 1Kg total without power chain)
... add a power chain that will deliver more than that weight, say a 40A setup can deliver 1200g thrust on a slow prop (can it? a 450 heli with a 40A setup can deliver nearly 2Kg, but apples and oranges)
... if the 40A set up including 15 minutes worth of battery pack weighs 400g... that gives a power to weight ratio of 6:7 which isn't bad, maybe too much even.

With the total estimated flying weight I need to figure out what a good wing loading is for slow stable flight. Not too slow or it won't ride bumps smoothly.

Anyone know of ball park figures for wing loading for flat bottomed foam layered airfoils?

The tail end, I'm less confident about. If it is to be a single pusher then a twin boom tail seems a little complicated. A pod mounted pusher on the top of the rear wing might be better, but can I get a prop on such a pod that will pull 1200g or more?

How far out the tail needs to be I believe can be calculated from the wing span, and you can then work out the size of the vertical and horizontal fins.

As you can see I am brave enough or foolish enough to attempt to design the thing myself, I just need to start gathering hard numbers and not ballparks estimates but... I'm also open to plans of similar machines, if anyone has any suggestions.

Paul
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Old Sep 06, 2010, 06:55 AM
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Joined Dec 2006
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Paul,

I-too-am-in-search-of-THE-‘panacea’

http://www.rcgroups.com/forums/showt...1108085&page=2
Post-19…my-solution-to-date

http://www.rcgroups.com/forums/showthread.php?t=1300632
Options-are-many
She-has-flown-with-tractor,-pusher-and-tandem-power

John

Pardon-the-‘dash’-myspacebarbitthedust
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Old Sep 06, 2010, 07:45 AM
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UK, North Down, Bangor
Joined Nov 2009
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I like the idea of steeling a wing. However I kinda liked the idea of building a wing. It looked like you did too, but opted for the Easystar wing.

I note your wing was inversely cambered like an old bipe wing. I was going for the layered foam approach.

1200x300mm 6mm base sheet - full aspect including ailerons.
6mm filler with a slot cut for the spar (1/3 wing width), about 200mm width
3mm high x 10mm spacer to peak the curve just forward of the spar.
2mm pre-packing taped sheet full aspect to laminate over the top to create a curve.
45* corner cut the leading edge tips maybe

Open issues:
Wing Dihredeal
Wash out
Ailerons
LE block or 2mm folded curve?

Like you I don't really care about the fuselage, it's just somewhere to hang everything else from.

I was thinking, as the wing is the most important part, start there. Then make a rough tail plane and fix it on a carbon rod for a fuselage. Add weight to weigh it down and balance it. Free flight throw it on a calm day and adjust until it flies.... or breaks.

If the wing flies, expand the carbon fibre rod into a space frame of some sorts. May be expensive and hard to glue together. I have no wood working tools beyond a dremel
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Old Sep 06, 2010, 08:10 AM
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NE Texas
Joined Jan 2008
557 Posts
Check the Aerial Photography ( http://www.rcgroups.com/aerial-photography-128/ ) forum for lots of plans that already work. Might give you some more ideas for your design. I'm especially fond of Power's designs.

Here's his pusher: http://www.rcgroups.com/forums/showt...hlight=loryder

John
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Old Sep 06, 2010, 11:28 AM
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1,455 Posts
Yep-for-sure-the-wing-says-it-all.

One-of-the-best-overall-wings-I’ve-flown-for-AP-is-
CraftAir-Butterfly(TowerHobby-GP/Dynaflite-Butterfly);
99-inch-916sqin-two-piece-polyhedral.
MFG-touts-50-ounce-(7.9-oz/sqft)ALLUP-but-63oz-is-absoutely-no-problem.
Airfoil-is-flatbottom-Craft-Air-‘Winddrifter’
She-will-stay-up-several-hours-on-a-20-size-four-stroke
Only-ONE-drawback-it-is-film-covered-stick-and-balsa-takes-maybe-four-days-bottle-to-throttle.-You-can-save-at-least-2oz-by-using-a-glass-arrow-shaft-or-carbon-rod-in-lieu-stock-steel-rod-wing-joiner.

I-have-Radiant-2-meter-wings-on-back-order-as-we-type:>))

RE-your…

“Open issues:
Wing Dihredeal
Wash out
Ailerons
LE block or 2mm folded curve?”…

>>Suggest-you-build-a-test-fuse-and-feel-the-difference-each-make-with-respect-to-the-other.

John
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Old Sep 06, 2010, 05:25 PM
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UK, North Down, Bangor
Joined Nov 2009
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I'm going to order the FPV gear this month I think and pack it all onto my ASW28. I think it will carry FPV gear OR the Go Pro.

If I increase to a 3S 30A power chain and a 11x8 prop. Hell it might carry both! Or melt the foam round the motor.

By then I'll have a better what exactly I need to carry.

It's still a puller so only an intermediate.
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Old Sep 07, 2010, 04:46 AM
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Canton,Ga
Joined Apr 2010
948 Posts
Take a look at this one from Mikeysrc.com. Silverfox has a thread here on his build of this design, and says it flys great. Nice'n'easy construction,too. Good Luck!
http://www.mikeysrc.com/FPV-Pusher-Plane.html
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Old Sep 07, 2010, 06:57 AM
gpw
“There’s no place like Foam”
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United States, LA, New Orleans
Joined Jul 2002
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While you're at it , be sure to check out the Trainer 1.5 ... everything you asked for ... Auto-stable ...hands off... SLOW!!!
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Old Sep 07, 2010, 01:25 PM
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UK, North Down, Bangor
Joined Nov 2009
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MikeysRC is a good place, it was his you tube build logs for the cheapest 450 heli that started me on what-was-once too expensive helicopters!

I have seen his FPV bird and considered it, but... for some reason I hate his fuselages.

Anyway, I did some specing out and weighing stuff.

FPV gear = 130g initial weight (cam/tx/lipo/cables)
GoPro w/ Case = ~200g

Now, my ASW 28 was recently flown with the GoPro, Case, sticky mount AND an extension arm (~230g) on the stock motor, ESC, 2S LiPo and prop. It barely climbed and glided like a brick, but it could fly.

So I'm thinking it will certainly carry the 130g FPV gear.

If I upgrade it to a 3S 1300mAh pack, 3S capable ESC and a larger slowfly prop, like an 11x8 folding, it should be grand. It may even carry the FPV gear and the GoPro without the case. Of course, with that weight and no wear to mount it aft of the wing root... I'd need to add tail balance weight too.
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Old Sep 08, 2010, 11:13 PM
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Charleston, SC
Joined May 2010
154 Posts
I can definitely recommend the FPV plane from Mikeysrc.com

You can checkout this thread for info on my build.
http://www.rcgroups.com/forums/showthread.php?t=1255811

The plane flies great! I have flown it with my RC Hero cam on board and with FPV/OSD equipment. It seemed to have enough power, but I would use a bigger motor next time. I used a 920kv, but the plans called for a 1000kv. I also would recommend a Kfm2 or Kfm3 airfoil.

Unfortunatly, my plane crashed on takeoff a couple of weeks ago. It was a bad hand launch turned worse by me freezing up. I ended up crashing into my neighbors house. Luckily we are good friends and he was the one that launched it for me.

I've been trying to build a "better" version for some time now, but so far I have not been completely happy with my own designs. I think I'm going to rebuild my crashed one with a few more changes.

Here is the original and my newest build:
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