wws2010

I was in the market for a super long lasting sailplane that is nitro powered. I am fine with arf but kits or plans will be prefered. I need it to carry about a half a pound or more and be able to take off and land in about 50 yards or less. Does anyone have any ideas? All imput is appreciated.

OzMo

My Feedback: (3)

Not to sure what you want here. Do you want a tough airplane that will last for years or a long duration flight. Might also make a difference what you want to carry. Use is a key factor in determining a certain plane.

wws2010

i am sorry, a long flight time and it will be carring 2 small wireless cameras and or tons of fuel

OzMo

My Feedback: (3)

I thought as much I would take a look on ebay as there are several powered (gas or glow fuel) planes there now . Seach "Sailplanes" a 15 to 25 would haul a couple of those around and are fuel SIPPERS. Any ailplane over 99" might work well and all the balsa kits could be converted without much trouble. A dynaflight butterfly comes to mind.

wws2010

will that be able to land in about 50 yards and how long can I fly for on the stock fuel tank?

wws2010

are there any other models available that boast the same stats.

OzMo

My Feedback: (3)

You may want spoilers or flaps to keep the landing short

khelsea

This might work. With a 52 4 stroke just above idle it will fly till I get bored. Rene Saenz " the funk works" U-2
Khelsea Lanny

BMatthews

A 15 will be enough power to fly a 100 inch model with a reasonable payload of perhaps an extra 1.5 lbs over the weight of the glider. Engine duration will be dependent on the fuel tank size. However a .15 will have trouble running consistently with more than 4 oz of fuel. Certainly a 6 oz tank would be asking for trouble. If you need more than the 20'ish to 25'ish minutes of run time the .15 with 4oz will provide then you need to get yourself working with a larger supply tank that feeds a small "float bowl" tank up by the engine. It would literally have to have a float in it and a needle valve similar to the float bowl in the old car, motorcycle and lawmmower engines of old. The idea is that the light suction power of the .15 to .25 needs to operate with a consistent fuel level so it can suck the same amount of fuel for the whole duration of the supply. There is just no way to provide that level of consistency with more than a 4oz tank. In fact in my experience even the 4oz tank is pushing it and you'd need to set it a hair on the rich side while full.

Takeoff is no problem. A handlaunch requires no distance at all. Landings would benifit from spoilers or flaps but a typical landing "slide" for such a model would easily be less than 30 feet.

You may also want to look at something more like a stick built old timer. They come out very light, can easily carry your payloads and can easily take off in 30 to 35 feet even in calm weather and land within 50 to 60. Less if you were to use a custom wheel brake system. It would not have to BE an old timer. It just needs to be built LIKE one so a basic box and rectangular wings is fine. Just don't use much wood.

wws2010

ok the problem with the small 4oz fuel tank can be solved with a drip tank that drips in at the same rate being used right? Or would something like a three way valve from an old autococker(Paintball gun) work with a servo attached and have that swich over once the time is right? woud those work with any plane i decide to go with? ive looked at all the designs and they work but all other imput is good and apreciated i am looking for something different

BMatthews

The three way valve from the autocockers won't work. You forgot that they also have an exhaust vent hole in them. However if it wasn't for that then yes it could potentially work out. But you'd need room for both tanks in the nose and in close as possible proximity to the engine.

The other deal I mentioned isn't a drip tank. I was talking about a full on supply on demand float controlled shut off valve so that regardless of how fast or slow the engine demands fuel the level in the float bowl would remain constant until the supply tank over by the wing was drained dry.


But this brings up the next question. Why do you want to fly for SO long? For most of us up to around 10 to 15 minutes is plenty. With that much flying time there's lots of time to reach altitude and take pictures to your heart's content without resorting to extreme solutions.

wws2010

no i am saying tht you route the engine in the center hole and the two fuel lines on the outer two, that would work right? The reason that i want such long flight times is that it will be a kind of uav for my senior project at school. And i really want to wow the teacher.

da Rock

Do some research for the magazine articles by Maynard Hill on the model airplanes he used to set his world records. The last one was a single flight across the Atlantic. Long enough time?

The articles cover the problems of using model airplane engines and tankage issues. His solutions were simple and clever. And his narratives explained all the over-engineered failures and why/how he wound up solving with simple.

dixielandsbigal

try a dynaflight butterfly. the one in our clubs flies FOREVER!

Furious Predator

i second the Butterfly by Dynaflite.

i have had one for over 4 years now. the kit goes for about $75, 99" wingspan, and is made for a .15 2 stroke. i have an OS 20 four stroke on mine. the entire setup RTF weighs about 5 pounds.

i only use a 4oz fuel tank for it, and it can run for about 20 minutes wide open, you can get 3-4 boosts from the ground up high into the thermals per tank of fuel.

it climbs just fine considering how little power the motor has.

the Butterfly is VERY VERY stable, vertually hands off flight, strong wing design, and incredibly slow landing speeds...you can almsot walk beside it.

very nice fuse construction, very durable, she can take some rough landings.

what i normally do, is use the engine to get her to about 500-600 feet, and shut down the motor...OR....let it idle till it runs out of fuel. keeping it in idle will keep it in the air if your having trouble finding thermals. but generally i find with this plane, it doesn't take a very big thermal to keep it going. i generally dont even look for them and it keeps going up. i normally land with a sore neck...which is pretty much the determining factor on how long i fly it.

now...for the downsides.

the landing gear design it comes with is garbage, your much better off leaving it alone and belly landing it. this leaves a cleaner look as well.

also...there are no spoilers. i have had a huge challenge trying to time my landings to get it roughly in the spot i want...she just doesn't want to land. its actually hard to get it on the ground. so very shortly, when i finish my electric BOT, i will be installing spoilers in the wings to assist with landings.

Check out my Run Ryder gallery for pics.
http://www.runryder.net/helicopter/gallery/15767/

OzMo

My Feedback: (3)

A Dynaflight Butterfly with an LA 25 at high Idle will fly untill your tired of it! And that 99" span could lift an old school camara. [8D]
I added spoilers to mine but it really doesn't need 'em.

dixielandsbigal

i wouldnt worry to much about the landing gear, just hand launch it and grease is in. if it were mine, i wouldnt even put is on, just skin the underside of the fuse with light ply and belly it in. ive never seen a butterfly take off from the ground well.

The other plane that comes to mind i cant think of the exact name. is it a Buzzard? ugly thing with a hgh, high wing. that will fly forever and ever.

Iflyglow

My Feedback: (79)

A cline fuel pressure regulator would allow you to mount what ever size tank will fit and give you no greif. Just simply tap the back cover of the engine and it will run exactly the same from a full tank to an empy tank with no leaning, and it only weighs about an ounce.

Furious Predator

thats what i have done. the Butterfly comes with a piece of ply for the first 7-8 inches of the belly, the rest is balsa. but i dont grease it at any level, i dont think its needed. im adding automotive wax to my BOT, but thats all im doing. normally after a day of several landings on the butterfly, there are just a few grass stains which wipe away pretty easy.

hand launches on the butterfly work pretty well, i normally have other pilots around me to help with that, its a bit awkward doing it on your own.

BMatthews

Nope it won't work. Not shown in those diagrams are the exhaust holes for the air on the side not being pressurized. The 3ways for the autococker paintball guns are more accurately called 4 way switches. There's the feed line (not counted) the two output barbs as shown in your diagram but there's also two small exhaust holes that are not shown. In the diagram when one side is being pressurized the other side connects the exhaust hole to the non pressureized line so the air can be let out as the ram travels.

It would require a modified or new outer body for the valve that only has the three barbs and avoids the exhuast holes.

I got into paintball myself last year. I've got 4 autococker style markers so I'm sure this is the case.

The best way to go for a long motor run would still be a main tank centered under the wing at the CG location and a small float bowl tank. Another option would be that fuel regulator that may work for this style of installation. However I'm not that familiar with the regulator but I know that a float tank can be made reasonably easy.

BMatthews

You're missing what I'm saying I guess. I agree that you hook it up that way. But when you've got the one side connected to the engine the other side is connecting its barb with the fuel line to an exhaust hole on the other side of the valve body opposite the barb. Your diagram DOES NOT SHOW THE TWO EXHAUST HOLES. But trust me, they ARE there. So the fuel from the non-selected tank would dribble out into the fuselage of the plane and the second tank would be empty when you try to switch to it.

The valve you show is the other style of 3way we use. In that one the exhaust ports out out the extreme ends of the body. Go back and look at your animated diagram again. Note how when it moves to one side that the other line is exposed to the open end? That would be fuel running out into your model's fuselage.

Using two tanks in the nose of the model would not be a good idea anyhow. That's 8 oz of fuel in the nose of the model that would be burned during flight. 8 oz of glow fuel weighs in at around 7 to 7.5 oz. That would be a lot of nose weight in a model of this sort to loose during a flight. Depending on the design the model may not be able to adjust to that big a shift in the CG location due to that shift. The flying charactaristics would change a lot due to this and it could easily end up outside of the ability of your systems to deal with. The other reason it's not a good idea is since it is a UAV that means no active pilot monitorying the flight. Who is going to notice that the fuel is running low and switch tanks?

If you need to make up a bunch of plumbing it's STILL better to do the float controlled constant level chamber and just let a higher placed larger tank at the CG feed that float chamber via gravity. Or play with and use the regulator so the engine sees a constant pressure over the whole tank.

Besides you still have not said how long a flight you are looking for in total. Two 4 oz tanks running on a .15 even at mid throttle won't last more than about 35 to 45 minutes at best. If you're after more then you need a larger fuel supply. And such a supply cannot be placed in the nose. It would have to be at the center of gravity due to the weight change during flight.

Rcpilot

My Feedback: (78)

It you REALLY want a long distance flying glider, then look at electric.

Learn to RE-wire a standard 3 pole motor to get more torque. Spin it slow. This will require higher voltage (11.1V li-po). A 180 size electric motor or even a 280 size will turn MORE than enough prop to keep it afloat. You don't need screaming RPMs like a glow engine. You just need enough SLOW thrust to move it fast enough to make it fly.

Rewind a small electric motor for torque and slow speed. Use an 11.1V li-po about 1500mah.

It'll fly 3hrs or more. Guarantee it.

It'll be lighter than even the smallest glow setup. You won't have to worry about fuel delivery. You won't have the hassle of assuring the engine runs for the entire tank of fuel. Electric is SIMPLE and RELIABLE. Why do you think any idiot can buy a park flyer and go flying? Because they are electric and there is no brain power involved in making them work. Plug it in and fly it.

Hint:
For tips on rewinding electric motors, see rccrawler dot com. Do your homework. It can be done.

wws2010

Now what airframe should I use with this rewired motor and will it be able to carry the payload I need it to? Also is that 3 hours of mixed flying or full throttle moving. I also kind of need it to have a very long range.

Furious Predator

well what are you trying to do exactly? just simply have a long lasting flight where you can lay back and relax all day? or something to do cammera work? or carry a 1 pound bomb at 5mph at a target 20 miles away for a couple hours? it would help us out a little bit if your questions and goals were not so vague. we need more details.

if your interested in electric, im currently building a newer version of the Bird of Time. fiberglass fuse, D-wing (super strong yet very light), and a very VERY powerful E-Flight Power 25 motor. its 550 watts, about 40 amps, 870kv, spinning a 14X9 folding prop. it will be using my Air Thunder 2200 3S lipo's (when ever they arrive). but with a 3 meter wingspan, you could take this thing pretty high and still see it.

you can buy this kit at the Espirit Models website, they are great people to deal with.

Tall Paul

Accomplishing all this with your first airplane is impossible.
The fuel system alone is over-thought, and impractical.
What you intend requires a fair amount of experience with all the facets of the project.. the airframe, the motor, and just flying ability.