Servo power?

80 inch Robinhood, (Curtis Robin stand off scale) that I bashed by removing the dihedral, beefing up the spars with spruce along with using hardwood in the cabin area, plus adding flaps and functional struts.

I used, T-Standard, A-BB Med, R-BB Hi, E-BB Hi, F-BB Med for each flap.

A 1400Mah NiCad battery has been sufficient for 10 years. ( The packs started out C size and are now AA size for the same capacity) I started out with a BB medium torque on the rudder but it didn't last long flying off of grass as well as pavement.

BTW it is powered by an OS BGX-3500 (2.1 CI)

Okeydokey, thanks for giving me a rough idea.

Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:

Here you go. Plug the information in and it will tell you what you need. There are also several other nice calculators there.

I dunno, but I strongly believe that any and all "camera" planes should be electric powered because electric motors don't vibrate a fraction as much as IC engines, especially gasoline ones, and you have the option to eliminate vibration completely by turning the motor off during a photo run, and then restarting it.

Tejas Pedro

| On 15 Nov 2006 03:46:30 -0800, snipped-for-privacy@digiverse.net wrote: | | >What size servos should I use for a 90", high wing, 25cc gas/petrol | >trainer/camera plane? | >STOL, Mildly aerobatic. | | I dunno, but I strongly believe that any and all "camera" planes | should be electric powered because electric motors don't vibrate a | fraction as much as IC engines, especially gasoline ones, and you have | the option to eliminate vibration completely by turning the motor off | during a photo run, and then restarting it.

That would be ideal, yes, but the electric equivilent of a 25cc gas engine would cost a bundle.

Like it or not, above a certain size, going electric costs a lot more than going glow or gas. Things are certainly improving, but the cost difference is still pretty signifigant, and it gets worse if you already have all the gas/glow support equipment you need, but don't have the electric support equipment.

As an example, I'm currently assembling an Ultrastick 25e. Motor = $90, ESC = $115, a single battery pack is around $130, though I'm cheating a bit by going with emoli cells I've already got. Setting up a similar glow setup for this plane would cost $80 for the engine, $10 for a servo and $10 for a gas tank -- and this is still a small plane by glow standards.

(On a side note, I'm really impressed with this ARF, though I haven't flown it yet. I'll bet if I had all my tools ready to go, ESC all soldered up, battery pack ready to go, I could have assembled it in a single hour. No glueing needed whatsoever!)

So build something smaller.

Nice one!

Yes, I thought about that and might do it electric, but I'm going for the cheapest option first (The strimmer motor was dead cheap). I can still use the plane just for fun if it's no good for filming. The plane will likely have to cope with fairly windy conditions like high coastal and mountain cliffs. It must also be able to carry floats as well as a decent video cam.

You hit it pretty much on the head. The plane will have to be a platform for a semi-pro video camera likely to weigh about 2lb. The engine will be anti-vibration mounted, as will the camera. The plan is to use it for footage for a travel documentary.

The ultimate challenge is to fly it through a rock arch in some sea cliffs. It means that I will have to fly it into the arch and set it for a slight climb and turn when the failsafe kicks in as it loses radio contact on the other side, it should regain RC contact when it comes into vision again. I think that would make quite a spectacular vid (even if it piles into the cliff!). Obviously I'll film all the less risky stuff first....

Do you want good pictures or not?

Electric motors vibrate less, much less, than IC engines, and can be turned off and on in flight, a huge advantage especially for quality minded photogs. It's laugh out loud funny to me that so many rc'ers can sink very many hundreds or even thousands of dollars into the brand new latest hobby gadgetry and yet somehow manage to continue to gripe out about the cost of electric power. Guy with a 10K plane and a 2K radio, "electric is too expensive." Get real, bro.

My vision of a camera plane is that of a 100+" span sailplane-like platform. "Old" electic flight technology (meaning much less expensive) motors & batteries would be more than sufficient power.

See? You're really just another electric fan!

Which, btw, I'm not. I gotta smell that exhaust. If I ever go all electric I'll need to have a downwind camp stove nearby boiling glow fuel.

Tejas Pedro

Of course. Videos, not just pictures.

Sure, but it needs to carry a broadcast quality video cam.

Sure, but it won't carry a 2lb pro video cam, possibly on a swivel-tilt platform, nor will it cope with windy conditions or flying uphill fast. You can fit a *still* or even a small consumer video cam onto pretty much any plane nowdays, but to shoot pro vids where I want to do it, the plane I'm building is my first choice.

Lol! I have 'lectric gliders too and some 400 size own design funplanes. I prefer peaceful electric to stinky, dirty glow. I left the pull start on this petrol engine (quite light one) and it starts with two pulls. No messing with glow batteries and needle valves. The fuel is cheaper too. Anyway, you can't get glow fuel where I want to film.

| >Like it or not, above a certain size, going electric costs a lot more | >than going glow or gas. | | Do you want good pictures or not?

Of course. And I want a pony too.

In any event, you can get pretty good pictures with a gas/glow plane by building in an appropriate vibration daming mechanism into your camera mount. Then all you have to worry about is the exhaust from your engine fouling your camera ...

| minded photogs. It's laugh out loud funny to me that so many rc'ers | can sink very many hundreds or even thousands of dollars into the | brand new latest hobby gadgetry and yet somehow manage to continue to | gripe out about the cost of electric power. Guy with a 10K plane and | a 2K radio, "electric is too expensive." Get real, bro.

I was thinking more of a $300 plane, $50 radio and $50 camera, but hey, get real bro.

If you've got $10k to put into a plane, you should be able to get great results, IC or electric.

| My vision of a camera plane is that of a 100+" span sailplane-like | platform. "Old" electic flight technology (meaning much less | expensive) motors & batteries would be more than sufficient power.

Yes, that would work nicely. And contrary to what the other poster said, as long as you watch the CoG carefully, a somewhat high performance 100+" glider certainly should be able to tolerate another

2 lbs of weight without much trouble, though if you mount the camera underneath, I wonder about landings without a landing gear -- I guess you'd want to add one.

| >(On a side note, I'm really impressed with this ARF, though I haven't | >flown it yet. I'll bet if I had all my tools ready to go, ESC all | >soldered up, battery pack ready to go, I could have assembled it in a | >single hour. No glueing needed whatsoever!) | | See? You're really just another electric fan!

Absolutely. But I'm not an electric (or glow) fanboy -- I know the advantages and disadvantages of electric vs. IC.

| Which, btw, I'm not. I gotta smell that exhaust. If I ever go all | electric I'll need to have a downwind camp stove nearby boiling glow | fuel.

I recall seeing some scents to add to your glow fuel at the R/C car shop. Seriously. I imagine it's only a short matter of time before somebody makes some nitro-smelling cologne, if it hasn't already been done.

Coincidentally I was in Austin last week at one of the Hobbytowns looking at that plane,the ultra stick 25e. I ended up with a Formosa glider which I will power with existing parts. Went by the Cedar Park shop(rc cars mostly) and bought an Evolution 1.0 NX for $150. mk

I could carry 2lb payload on my 200W electric 60" old timer..just.

Certainly a 5lb plane with 350W - an easy sort of cheapish electric setup could carry 2lb. Something like the venerable senior telemaster is in that ball park. Power train about $200

You should see some of teh slope sorarers mate! They are FAST as greased weasel shit.

A fellow in our club just maidened the Ultra Stick 25e, and loves it. Of all of the electrics I've seen, this one is pretty awesome. I know very little about electrics, but this plane will serve to spur me into learning more about them. The plane is just dead solid. The guy who has it is not usually impressed with electrics, but I sense a difference in his attitude with this one. Of course, he has more motor than he needs on the plane, but it really performs extremely well with it. I believe he said it is an AXI that is two steps over the one which he was intially considering.

I'm still sticking with glow for now, but I have ventured into the dark side in a couple of small ways. We'll see how those "ventures" go.

Harlan

Having built a low wing plane very similar in spec to what you mention I'd recommend something around the 10Kg rating. That will be more than adequate for what you need, and ideal for aerobatics while maintaining a safety margin.

Do a search for a servo torque calculator. Provide the dimensions, max deflection, and max airspeed for a control surface and see what comes up.

I used Hitec HS-645MG servos. 7.7Kg at 4.8V (from memory) with almost 10Kg at 6V.

Watch 5 cell packs as fully charged they could be outputting well over 6V, enough to give some receivers/servos a bad case of the jitters. I'm using a

2500mah 4.8V pack (NiMh) but haven't done enough flying to see how quick they run down (battery checker says OK after 3 flights).

The brand new strimmer engine cost me =A330 ($50 US)

It needs to be STOL, fly in windy conditions, cope with turbulence and be able to carry floats as well, with a decent climb rate. The video camera may need to be on a tilt-swivel mount. I already have small electric and glow planes (glow is out because the fuel is unobtainable) I can always fork out for a big electric setup at a later stage, but right now this is the cheapest and favourite option. The thing is, the locals there might get interested in building some, and strimmer engines are widely and cheaply available. Conversly, glow engines would have to be got mail order and expensive glow fuel would have to be delivered by ship because it's volatile, lead time 4 weeks. I'm fed up with glow engines anyway.

Yup, though my plane will be a high winger and of fairly modular build as I will make what fits in a suitcase here and finish off the rest on the Island. I can make the whole nose section, apennage, control surfaces and undercarriage here and assemble the rest of the fuz and the wings over there. Incidentally, their main building wood there is Japanese cedar, selections of which are similar to medium grade balsa. It's also incredibly cheap.

Nice chap kindly posted a link above already, I didn't know there was such a thing before.

I have a couple of the plastic gear 645s, but I'm ordering some cheap Tower Pro servos from Hong Kong.

I have plenty of 2300mah NiMh AA batteries ready to solder up into flight packs. I will check the max voltage as you suggest. Leaving them to settle after charging probably helps.