63 replies to this topic

[headhunter23]

Other than a predator.

I've recorded a couple videos with cularis but you can really tell when motor is on. For example holding it in my hands with half throttle you see the tail of the plane fluttering even with the glass on it. So've been thinking it would be best for a video platform to have the prop as far away from the video in the front. This would reduce interference in the tail surfaces, plus help push the plane, no issues about full throttle starts providing it's all trimmed properly etc. (currently with pylon pusher, can only half throttle start).

So whadya guys think? I think this really is a step towards making better videos, no prop in the photo, less interference on surface controls, etc. Although this would rob power of the plane and efficiencies of the motor too... anyways if you've seen any designs post a link please. Am interested in cutting some weight on cularis but would be a pita to do as I would be losing a good chunk of the rudder. Not to mention would need wheels for sure to protect prop.

Ivan.

[Mr.RC-Cam]

I'm a little confused by what you mean, but if you are looking for a big pusher plane for A/V work, then Centexflyer swears by the Zagnutz wing. He builds them big; The 80" size looks like fun. I hear they are very stable.

http://home1.gte.net...ills/index.html

[headhunter23]

Good idea... I guess the flying wings aren't as affected by gusts with the lower profile. But yes what I meant was something big, slow and a pusher config with motor directly at tail.

Have been thinking of making a giant slow flyer... like enlarging plans, but I'm sure that could really be affected by wind. I did see a guy with essentially a giant foam piece with a dual flipper setup, extremely slow and extremely consistent. Just can't see how you would add camera and land without wrecking it.

any other ideas welcome.

[W3FJW-Ron]

No matter what you put up there, it's going to be affected by wind unless you can make a brick fly. What exactly is your criteria for an FPV platform ??

Edited by W3FJW-Ron, 16 May 2008 - 11:50 PM.

[Terry]

Why not turn it into a twin ?

Terry

[headhunter23]

Terry what do you mean turn it into a twin, what do you mean by that? A biplane? Or put motors on wings? I'm just looking for a platform that can handle gusts and such better and fly slow. And it needs to be large just due to the payload. Am I wrong in stating the motor should be at the back of the plane for av platform?

Ivan.

Edited by headhunter23, 17 May 2008 - 07:54 AM.

[Terry]

No Ivan, not a biplane, a twin.
Put a motor/prop on each wing like the Twin Star.

The motors are away from the body to help your vibration issue, thrust line is good and it wont be tail heavy.


Terry

[headhunter23]

It's not tail heavy, it's actually balanced, I think it would be if I put the motors at the front of each wing. What if I put it at the back of each wing... I don't think I've seen that yet. I wouldn't mind making it a little tail heavy... kinda thinking I should do up some sort of fancy mount of the camera to try and get rid of vibration and such at that point.

Ivan.

[Terry]

Yep back of each wing is good, there is a UAV like that, don't remember what it's called for the moment. Just watch out for your fingers if your hand launching.

Tail mount is ok but balance and the thrust line need to be good plus you still need to watch your fingers.


Terry

[headhunter23]

Thanks, will see if I can find it.

Ivan.

[headhunter23]

Well been munching on the whole what to do next part of the cularis flying hd camera setup. I like the idea of putting motors on the wings, but am still leaning towards cutting up the tail, converting it to v tail and put the motor straight back so it's a pusher. Would reduce some weight, kind of, with hopefully less tail affected by gusts(hopefully, my thinking about this might be wrong).

So... if I did all that, I could remove the motor mount that is currently on it(pylon) allowing to setup a home made steady cam system for the hd camera, using the battery pack as ballast, or vice versa. Also contemplating about pulling all the fibreglass and redoing it so it's lighter, this was my first attempt at fibreglassing foam. Worked out well but I don't think I need three coats on it (three on the bottom).

Goal is to have nice steady video, which means a slow flyer, the cularis is almost there, would be nice to have it a touch slower, which would mean less weight, more aerodynamic(right?)

Anyways shoot your ideas out. Always open to outta the box.

Ivan.

[Kilrah]

I'm just looking for a platform that can handle gusts and such better and fly slow.

Goal is to have nice steady video, which means a slow flyer, the cularis is almost there, would be nice to have it a touch slower, which would mean less weight, more aerodynamic(right?)

From my experience, those 2 criteria are actually incompatible. The faster the plane, with higher wing loading, the more stable it'll be and the better it will handle the wind. When you hit a gust at 4x its speed, you'll always be less likely to move than when you're equal. Now you'll have to find some kind of compromise.
That's why my opinion now tends towards having 2 different platforms to cover all cases, one like a quadro for slow speeds (0-~50km/h) like you will want when you're close to the subject and a relatively fast plane for the rest, like shots you'd take from higher altitudes (effectively cancelling a bit the sense of speed). I don't think a single platform can handle the whole range fine.

The other day we were flying our 2 Moviestars in formation with a friend. It's the typical plane you'd be looking for (high payload, around 500gr and large fusealge volume with clear view at the front, 2 wing-mounted motors, slow). It was pretty windy but not very turbulent, but we were being shaken qute a bit. Not a lot, but still enough to be annoying on the video. It doesn't take much at all and sometimes it's even better when it moves frankly than when it's a constant slight shake IMO.
Just after that, I flew my Funjet (new, only have 2 flights on it, one normal and one FPV) that flies at 100-150km/h easily, gonna find that out soon now I have the OSD on, and it was absolutely rock solid, with VERY smooth movements around its axes, vibrationless and it really felt both like real jet flight and the "flying eye" you'd expect to see where all movements feel natural and "dampened". I was really impressed and never saw that with another plane (I mostly fly slow things).

Now, the Moviestar definitely has a drawback as it's foam and the wing tube is short, so the wings are quite "elastic" which sure doesn't help against its bouncy behavior. On the funjet, the motor being right at the back and clear of everything must surely help against vibration, like you said. Now, If I were to design a plane for video, I might try copying the Moviestar, but building it as a rigid frame (standard wood-covered foam or wood structure), making sure the motors are far out on the wing enough to clear the tail of turbulence, and with ailerons. I'm sure it would help.
And if that's not enough... make it a bit thinner so it would fly faster. No miracle there.

IMO the cularis with a motor on the tail is a dream, unless you cut the fuselage rear and make it half its original length you'll never be able to balance the thing with the weight of the motor in the back. And by doing that you'd lose most of the tail's armlength which provides the stability.

Gliders are meant to have something heavy at the front (the pilot, in RC as we want to keep the scale look that's either a motor and battery or a lead counterweight) and have the least possible weight at the back, so the wings are close to the front, and any bit of weight on the back will be very hard to compensate. Common pushers and jets have something heavy at the back (powerplant) and nothing really significant at the front, so they have the wings far back and won't be able to handle a lot of extra weight at the front (no payload).
If you want a motor in the tail, and a heavy payload with a clear view at the front you'll want the wings closer to the middle. But you won't have much flexibility as it will be well balanced only in one configuration.
The Moviestar and such things meant to carry a lot of stuff have a light tail, relatively long, and all the rest is packed right around the CG (motors are on it, fuselage is fat and short so that the payload you add has a very small arm length). That's why you can vary the payload between 0 and 500gr (on a plane that's meant to fly at ~1.3kg) and only have to shift the battery a couple of centimeters to compensate for it.
Which draws my conclusion of ideal configuration for that use. Unfortunately, nobody really makes such planes, so if you really want one it will have to be a custom build.

Edited by Kilrah, 18 May 2008 - 01:26 PM.

[headhunter23]

Awesome input kilrah. Btw wanted to say your "slow and low" video was amazing, excellent choice in music. I really like all the stuff you've done. I wished they had the moviestar here but apparently that will never happen. Heck I've been waiting for three months now for two twinstars that I was going to merge together. They still haven't come in. I have no idea how multiplex usa is supposed to make money when they don't have product to sell, I would fire everyone that is responsible for having product to north america for not doing thier jobs.

Not too sure about the balancing stuff, I have 4 servo's in the tail (two are dead, should never have put them bellow the elevator but still wanted stock location stuff, well atleast where the cables would have gone. Those alone have to be 40g, plus the 30g 900mhz tx, hmmm... you might be on to something, motor is 154g, but with wheels on the front.... ah crud... need to think. Your right in having to shorten it for sure, but I am expecting to add more weight to the front, especially if I move servo's up to front, and tx... cut off rudder make v... lose a little there... darn going to certiainly need to customize it further. Well gotta say the cularis won't look like one when I'm done with it.

Maybe I should get a big carbon fibre tube and just hack the back off like the moviestar, too bad they only sell so big.

Gotta think more... bugger.

Ivan.

Edited by headhunter23, 18 May 2008 - 04:04 PM.

[FFooccuuss]

I don't know if anyone else is flying canards FPV, but I fly a Long-EZ .46 (gas) plane with a camera up front. I also built an electric-powered foamie canard (from scratch) of a similar design with a 40" wing span. My little electric canard gets as slow as you can imagine and handles wind impressively well (I've taken it out with 15 and 20mph gusts). Anyway, I just thought I'd give my 2 cents. Maybe something like this would be up your alley:

http://hobby4less.co...21c99940a2f79ec

From my experience, canard models tend to be very pitch stable (smooth pitching, hard to stall), but you have to be careful on the yaw - meaning, make sure you have enough fin area on the wing tips. If you get jerky with the sticks, they tend to wobble a little on the yaw axis. But I like 'em... good luck on whatever you come up with.

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[headhunter23]

have ya posted one of the video's online?

Found a really slow and steady plane but it would need to be the 200% version with ailerons. Look up "puddle monster" on youtube. Fricken love that thing, going to try a 66% version just for fun.

I've come to the conclusion that the only way to avoid any sort of tail wag etc is to only fly early in the morning or late in the days for the video's. Unfortunately getting some vibration from the prop and motor still, driving me nuts, balancing that stuff is very difficult. I really think someone needs to build a whole new plane design, slow and steady like a puddle monster, prop at the back, very light but able to take a 200-500g load.

On the other hand the quadcopter looks very interesting too... lotso solidering, man that looks difficult for some of it. Very precise doing the boards.

Ivan.

[Kilrah]

man that looks difficult for some of it. Very precise doing the boards.

That's why you can buy ready-made boards

[headhunter23]

Might have to do that ... hadn't looked too much into it yet, just started reading though arthur P's 200 page thread! Yikes, going to be a long one.

[headhunter23]

Been a while since I visited this thread, had read the entire post on the quadcopters... very interesting. I've still been struggling with a platform, had tried a 72" zagi style ship, roll worked out pretty good but then pitch kinda went in the crapper. Very sensitive on pitch... so am trying another. Unsure if any of you have seen eddie weeks unusual platform, here's a video. It's really a simple design, at a min 19sec for a few breif seconds is the perfect video that I want to do.

Mine is kinda on the same concept except(still just as ugly) it's powered by one motor at the back(although if it doesn't work out I have two motors ready and waiting to go on the front) and I only currently have 2 fins on the bottom. I've been thinking about putting one fin on the top, so going to do a quick poll. The other question is where the heck should I start out with cg? I've got a 500g camera that will go in the front, and a few batteries to beable to mess with cg. Current dimensions are 76" wide, 46" long, still need to mess with all the electronics, and pop in servo's etc.

So just to reiterate:

fin on top? one or two?

Where should I start out with cog?

Thanks to those that respond.

Ivan.

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[Terry]

Is that little prop/motor going to have enough thrust ?

Also you appear to have the motor at the back which will mean no airflow over the control surfaces.

C of G 20% for starters.

EDIT,
Go for 2 motors at the front with RH and LH props if possable.
2 fins monted on top of the wing in line with the motors as far back as possable.
Terry

Edited by Terry, 14 August 2008 - 02:49 AM.

[headhunter23]

Was motor off of cularis, that weighed in 2.3kg, this thing is 2.3kg without camera and batt, so probably closer to 3kg. The motor supposedly does 800-1200g thrust, was hoping it would be enough... I think the motors on the front would be better but trying to have motor behind camera. Will do the fins like you said and cg, try and if it doesn't work out put motors on the front. Thanks.

Ivan.

Edited by headhunter23, 14 August 2008 - 03:41 AM.