Really slow model?

[vintage1]

Yeah, never mind all this speed craze, how about kicking ideas around for something that barely exceeds a brisk walk...and yet is capable of flying in a 5mph breeze outdoors?

Got to be a winged model - not 3d Hovering here..autogyro maybe? Biplane? Pterodactyl?

Depron? Carbon fibre? Balsa and film?

Probably IPS powered...'rubber' model maybe?

Toss ideas in. Looking for an interesting challenge.

[Tom Harper]

vintage,

I meditate on this once in a while and usually talk myself out of building anything. It's a drag issue. Brisk walk = miniscule reynolds number so drag sucks.

The other possibility is balance drag with thrust. In that case you want lots of drag developing lift in the prop blast. A channel wing or extreme flaps configuration. The last time I got on this kick I settled on extreme flaps ( Bruce suggestion). Talked myself out of it before butchering any balsa.

[Ron Williams]

Slow Stick.

[FRAMEDNLVS]

gone fishing

[shaneyee]

I am thinking very light wing loading... maybe 1oz per sq ft, undercambered single surface wing and rudder/elevator control for simplicity/light weight. This is just following what the indoor free flight guys do... maybe even eschew the elevator servo and use the throttle ESC for altitude control. Might be fun to build if I had an easily accessible gym nearby...all using stuff I already have. No escapements, super micro receivers etc...

Shane

[HELModels]

Vantage, Try one of these, stately, slow ;)

http://www.rcgroups.com/forums/showthread.php?t=479534

I'd say lower the wing loading and use an airfoil with 6% camber and 7.9% thickness. My first attempt used that type of foil which was based on RAF32 and it had good wind penetration at 8 oz./sq ft loading. Had the wing loading been half that, I'm sure it could have flown slower and still met your 5 mph. wind constraint. I'd also say make sure you use a large slow turning prop.

Harry

[vintage1]

Vantage, Try one of these, stately, slow ;)

http://www.rcgroups.com/forums/showthread.php?t=479534

I'd say lower the wing loading and use an airfoil with 6% camber and 7.9% thickness. My first attempt used that type of foil which was based on RAF32 and it had good wind penetration at 8 oz./sq ft loading. Had the wing loading been half that, I'm sure it could have flown slower and still met your 5 mph. wind constraint. I'd also say make sure you use a large slow turning prop.

Harry

Well it was the challenger that got me thinkong that I could actually do better than that..

The key is enough stength in a huge wing isn't it? Or to use an autogyro where the reynolds numbers of the wing are higher because of its rotation.

Large slow turning prop ois of course mandatory..

I am thinking that if I could build a 50" span model down to 8 oz or so..I could get stall speed sub 10mph anyway.

IPS running 9 or 10" prop with 20mph pitch speed is on...

[Tom Harper]

Vintage,

Quick estimate says you have to build a 50" span 3 sq ft model with an auw of 24 oz. Good luck!

The models offered in post #4 are more in the right direction. The NASA PAV study shows that low aspect ratio, lifting body, simple construction can achieve 8oz per sq ft or it's scaled equivalent.

I am building a 4 sq ft faceted construction model with a goal of 36 oz auw for .25 glo, structure and RC stuff. It's the usual foam board material. My goal for the structure is 16 oz.

For an electric you could build a frame of spruce or balsa and cover the panels with monokote (or whatever). A delta shape 3 sq ft lifting body would be 35" span and 18" length for an AR of 2.8:1. Thickness of 3-4". Total structure weight could run as low as 9 oz.

This link has a lifting body model that you can print out and assemble. It's less than 1:1 AR but it glides well. I used printer paper and left off the rudders (too heavy).

http://www.currell.net/models/mod_free.htm

The NASA PAV study indicates that low AR Lifting body has major advantages over conventional. Take a look:

http://members.aol.com/slicklynne/facet.htm

[Bill Glover]

Yeah, never mind all this speed craze, how about kicking ideas around for something that barely exceeds a brisk walk...and yet is capable of flying in a 5mph breeze outdoors?

Simple - IFO or Mini IFO. Lots of wing area and will fly very slowly and stably at high AOA, but low frontal area and will fly much faster if you want.

[vintage1]

Simple - IFO or Mini IFO. Lots of wing area and will fly very slowly and stably at high AOA, but low frontal area and will fly much faster if you want.

That may be in the right sort of direction..basically a carbon 'bow' frame with solite or litespan on it..

Want it to look 'interesting' too...but annular is not my bag.

Hmm..

[Bill Glover]

annular is not my bag.

How about this then. Same wing area and weight as my Mini IFO, and because the wing covering is heat-shrunk it has quite a cambered section ... not flat-plate at all.

[BMatthews]

The problem with setting it up so it can fly at a slow walk is that the high speed will be a fast walk or a jogging speed. "We" jog at about 4 mph. So even a 3 to 4 mph wind will kick the pants off this slow flyer.

But for calm summer evenings it would be a lot of fun.

As for the GWS Slow Stiks we can do a LOT better. Those things have more drag than lift. The terrible airfoil it uses is designed more for strength of the single surface foam than for flying.

[HELModels]

3 MPH = 4.4 Ft/sec. ; 5 MPH = 7.3 Ft/sec

Merely stating a fact that might come in handy

[vintage1]

How about this then. Same wing area and weight as my Mini IFO, and because the wing covering is heat-shrunk it has quite a cambered section ... not flat-plate at all.

Whats the weight on all that...?

I an fancying going BIG...how big for say a 9-10oz model that stalls at say 8mph.

I fancy that a rubber model of 40" span was around that figure.

[BMatthews]

Most of the vintage rubber models were built according to the 200 sq inch Wakefield Cup rule. The later models went with the 300 sq inch open class size.

I'd say that most of the 40 inchers will be of the 200 sq inch size models.

According to FoilSim at 8 mph a....
48 inch x 7.2 inch wing
7% thick x 7% camber at 6 degrees AoA
... will generate a whopping 9.8 oz of lift. If you can keep it to that weight then you're in like flint.

That sounds about right. My 7 oz AUW old time rubber model flies fast enough that I need to run as fast as my 52 year old legs and lungs can carry me if I want to pluck it from the air on a run rather than letting it fly to me.

[mharms]

So if I wanted to maximize the wind tolerance of a very low wing loading model, what kinds of things could I do in the design? Wind-wise, is absolute weight of the model an issue as well as the wing loading?

Mark

[HELModels]

Most of the vintage rubber models were built according to the 200 sq inch Wakefield Cup rule. The later models went with the 300 sq inch open class size.

I'd say that most of the 40 inchers will be of the 200 sq inch size models.

According to FoilSim at 8 mph a....
48 inch x 7.2 inch wing
7% thick x 7% camber at 6 degrees AoA
... will generate a whopping 9.8 oz of lift. If you can keep it to that weight then you're in like flint.

That sounds about right. My 7 oz AUW old time rubber model flies fast enough that I need to run as fast as my 52 year old legs and lungs can carry me if I want to pluck it from the air on a run rather than letting it fly to me.

7% camber? hmmm, I chose 6% because the drop off on the top back half didnt exceed the magic 7 degrees. It probably doesnt matter that much.

For a 6 degree alpha, what does FoilSim say is the Cl for the surveyed foil?
I'm guessing it is roughly 0.8 and is best L/D. A chord of 8" might be best even if the AR goes down a little.

[Bill Glover]

IMO anything 'conventional' that can fly at a walking pace is going to really struggle in a 5mph breeze.

Vintage, you will remember the Model Engineer Exhibition at Olympia. I had an ultra light 40" span model that flew at a walking pace, and the biggest problem was getting it to and from the car in one piece! One year the draft of air as the sliding doors in the foyer opened caused the wings to fold :D

[BMatthews]

So if I wanted to maximize the wind tolerance of a very low wing loading model, what kinds of things could I do in the design? Wind-wise, is absolute weight of the model an issue as well as the wing loading?

Mark

Reduce airfoil camber, add excess power and set the trim so the CG can be places back near but not quite on the neutral point. Then you can put the nose down and power through the wind.

Something to note is that legions of free flighters over the decades have found that thin is in for low speed flight. 7% is actually thick for "us" but around that thickness is seen as a decent compromise to be able to keep the spars thick enough.

I didn't take note of the Cl but it would be easy enough to replicate it. But the higher camber stuff is quite happy operating up around a Cl of 1 but at low speeds the stall occurs at a lower AoA then at higher Reynolds numbers. And it's that stall that is often the limiting factor rather than the attainable Cl at typical free flight Reynolds numbers. Way back when Frank Zaic and others showed that free flight stuff operates at it's best at around an AoA of 6 degrees with the stall typically occuring shortly after that.

[Bill Glover]

FWIW my walking pace model used a Göttingen curved plate section ... about as thin as you can get, but heavily cambered.

[mharms]

Reduce airfoil camber, add excess power and set the trim so the CG can be places back near but not quite on the neutral point. Then you can put the nose down and power through the wind.

Thanks Bruce!

Anyone have design tips about maneuvering and yaw/spiral stability in the wind? I would imagine that you would want to have the least amount of side area necessary for stability. Where should the CLA be ? I know it should be back behind the CG, but keeping it low should also help, right? What about dihedral -- in windy conditions, should it be kept to a small amount to avoid rocking? Would down-turned wingtips be helpful for windy conditions?

I think these questions are still relevant to this thread, since wind is a big issue for slow/light models.

Mark

[BMatthews]

Mark, none of that matters unless you fly in turbulent conditions. And that level of turbulence only arises when the wind is blowing far stronger than a light model can deal with. With a steady wind none of that other stuff matters because it's like that "river of air" thing again. The model never sees a cross wind in the "river". It's just what you think it sees. Polyhedral and oddball side area stuff flies fine in wind as long as it's not a gusty wind with lots of direction changes that catch the model by simulating unwanted yawing action. BUt as said it's been my experience that gusting turbulence of that sort only comes with stronger winds than you can fly a super light model in anyway.

If you're still game then define what your idea of "light" and "light wing loading" is that you're wanting to use for this model concept. So far we've been talking indoor or very light outdoor style stuff. But you're trying to raise the bar by more than one notch by the sounds of it.

[mharms]

Bruce,

Actually, it was turbulent conditions that I was thinking about. I'm flying sub-15 inch wingspan, sub-ounce planes (wing loading works out to around 2.5 to 3oz/sq ft). Its not uncommon for the wind to be 5mph where I fly and it gets a bit turbulent, since the wind comes through some tall trees before entering the open area. Just to make it trickier, these are all flying wings I'm talking about -- a fixation of mine.

One of my first wings (see my avatar) actually flew quite well in gusty wind (maybe 8mph gusts at ground level). Neat thing is it didn't have any vertical surfaces -- although the wingtips were downturned and towed in (my guess is this effectively gave some vertical area and some washout effect as well). I lost that plane and have since been playing with other flying wing designs of the same general size (but not the exact same design). Interestingly, even using vertical fins, I still have not matched the wind handling of that earlier design. So all this has made me interested in what makes for good wind handling (incl. gusty wind) in a really light design.

Mark

[peterangus]

Got to be a winged model
If we remove this condition, then the helicopter, the 3D model, and the Harrier all qualify.

What do they have in common?

They all retain controllability down to zero airspeed.

Even with completely still air, controllability is a necessity.

In the real world, controllability must be sufficient to cope with the inevitable air turbulence.
--------------------------------------------------------------------------

If we reinstate "got to be a winged model", then out of these three choices, only the 3D model now qualifies. But since hovering is not a requirement, it could, with advantage, be propped so as to gain some pitch speed in exchange for a reduction in static thrust.
--------------------------------------------------------------------------

An essential charactristic of the 3D model is that it retains 3-axis control at zero speed by virtue of all its control surfaces being immersed in the propwash.

[vintage1]

All I can say is that this thread has done excactly what I hoped - brought out lots of experience and ideas from 'those wot ave dun it'..

The big issues seem to be structural integrity at very low weights, and ability to handle turbulence.

I am taking Bills info to heart..and think that a thin ultra curved wing might be the ideal - well that's what birds use..

No idea if I'll get to buld this, but its all going into the mental pot for pondering..

[peterangus]

How about this?

Control by throttle, rudder and elevons.

[BMatthews]

Bruce,

Actually, it was turbulent conditions that I was thinking about. I'm flying sub-15 inch wingspan, sub-ounce planes (wing loading works out to around 2.5 to 3oz/sq ft). Its not uncommon for the wind to be 5mph where I fly and it gets a bit turbulent, since the wind comes through some tall trees before entering the open area. ....

That's different then. The trees are adding a lot of turbulet vortices to the airflow that would not normally occur at those speeds.

This sort of turbulence by it's very nature is unpredictable and the mass of the model reacts with it to make the model experience rapid and uncontrolled variations in the apparent yaw angle. The trick would be to use a design that does not rely on yaw angle response as part of it's rolling and turning mechanism. This means flat wings with ailerons. As soon as you try to use a rudder and dihedral setup you leave yourself open to the sudden yaw angle variations causing rolling responses and unwanted turns. Drooping the tips may help avoid the stronger roll response from the turbulence but it also reduces the rudder to roll coupling so the model does not respond with the same quickness that you may want.

Along this line any tip fins you use should be setup so they have as much area above as below the center line.

So what are you left with? A variation of the old Todd's Models Winger would be ideal. Flat wing, elevons and vertically symetrical tip fins.

Or keep experimenting with the original drooped tips design. You're right in that the toed in drooped tips gave you the fin area and tip drag to help autostabilize the yawing action. The rear prop disc also creates a fin effect and that likely helps with your stability as well.

[Scaledown]

I'm intrigued by the structural challenges involved. I would make the wing from very thin balsa sections and indoor covering materials and brace it like a typical WW1 monoplane - kevlar thread braces from numerous points along the wing to a central post above and below the fuselage.

[Bill Glover]

A large, ultra-light, thread-braced model is fine until you come to the practicalities of storing and transporting it! I honestly think the Stubenfliege (which is a 10 year old design) still takes some beating if you want a practical 'walking pace' model. The web page for this plane hasn't been updated for 5 years so it's "pre-LiPo", but you get the idea:

http://www.braunmod.de/eproduktb.htm

[vintage1]

I think thats true of a smaller model..but a larger model can be a little less fragile.

What we want is high strength and stiffness to weight mainly..CF has got to be best in that.

Or a really low density composite, like depron with tissue covering glued on.

[Mister UHU]

Hi Bill Glover,


I'm sure you don't remember me.

I spoke to you briefly at the Christmas Model Engineer Exhibition,
at Olympia, about 10 years ago.

You had a small red balsa pylon racer,
powered by a screaming Cox glow motor,
WITH A BACK-TO-FRONT PROPELLER.

I thought your model looked just right,
and wished my old balsa models were as accurately made.

You were talking of having the plans made up
by one of the UK mags.



Now after more than 20 years break,
I am flying some RC models again.
(Various small electric foamies etc.)

Unfortunately I am finding it a bit too addictive,
time and money wise.


What do you think of the new equipment,
such as LiPos, CD-ROM brushless motors,
sub-micro radios etc ?

Some of the latest TOYS are very high tech, and amazing.
Have you seen the X-Twin mania,
AWESOME !!


Your litttle red pylon racer,
would make a nice electric conversion.
Maybe you have already done this ?


Glad to see you are still modelling.
You are one of those modellers,
that actually knows what they are doing,
unfortunately not so common.

I wish you many more happy flights.

UHU

[zen4013]

Hmmmmmm...I dunno nuttin about aerodynamics, but in the real world, something like this flys slower than any aircraft out there (except a hot air balloon mebbe).
If the canopy was rigid or semi-ridged it would a bit easier to handle I guess....also, size of the canopy is up to you :p
http://static.rcgroups.com/forums/attachments/3/1/2/4/9/788880.thumb?qTu6oJVgp7g0p8IlMzIlZl0dpTp2Amt9BQtjB 7ygLJqyWGWTnaOyMj==

PS Manufacturer claims this model as pictured flys between 7 and 10MPH

Zen

[zen4013]

..Or this mebbe? Wing Loading under 3 oz!

http://www.blac.net/

[Bill Glover]

My old Gottingen curved-plate model pre-dates Depron so was hot-wire cut from white foam. The plan was to trim it out (to check it flew), then skin the wing top & bottom with lightweight modelspan tissue applied with thinned epoxy (the laminating kind, not 5 minute :D). I kept the wing blanks ... the approach was to lay the tissue on plastic film, wet with brushed epoxy, put that on the bottom blank, wing core on top, more plastic film / tissue / epoxy laid on top, top blank, then weight down and leave to cure. Afterwards peel the plastic film off to (hopefully) give a nice smooth (and coloured!) surface, weight gain should have been minimal.

That was the theory, in fact it flew so well I never bothered with the skinning and put up with it being a bit fragile! :)

[Bill Glover]

Hi Bill Glover,


I'm sure you don't remember me.

I spoke to you briefly at the Christmas Model Engineer Exhibition,
at Olympia, about 10 years ago.

You had a small red balsa pylon racer,
powered by a screaming Cox glow motor,
WITH A BACK-TO-FRONT PROPELLER.

I thought your model looked just right,
and wished my old balsa models were as accurately made.

You were talking of having the plans made up
by one of the UK mags.



Now after more than 20 years break,
I am flying some RC models again.
(Various small electric foamies etc.)

Unfortunately I am finding it a bit too addictive,
time and money wise.


What do you think of the new equipment,
such as LiPos, CD-ROM brushless motors,
sub-micro radios etc ?

Some of the latest TOYS are very high tech, and amazing.
Have you seen the X-Twin mania,
AWESOME !!


Your litttle red pylon racer,
would make a nice electric conversion.
Maybe you have already done this ?


Glad to see you are still modelling.
You are one of those modellers,
that actually knows what they are doing,
unfortunately not so common.

I wish you many more happy flights.

UHU

Hi Mr UHU, many thanks for your kind comments!

My little red pylon racer became a plan in RCM&E mag. in 1997 (IIRC). We raced them every year at Olympia until the show moved away - one year we had almost 30 of them there! I built a 4-channel one too with a throttled PAW .55 diesel and flew that at Olympia as well (even raced it one year after my Cox one had a mid-air!). I still have both the models fully airworthy, my original one does indeed fly as an electric now with a Speed 280 Race and 7x720 AAA nimhs!

[lenniegordo]

the rcHover disk, verry slow, verry high payload.

http://rchoverdisc.com/

[BMatthews]

the rcHover disk, verry slow, verry high payload.

http://rchoverdisc.com/

Now THAT was slow! I loved the trash can carrier operations... :D

[Sonofagun]

70" airsurfer
http://www.rcgroups.com/forums/showthread.php?t=498099

[yakman]

This is what I am going to build to satisfy an urge for really slow.

[Aio_1]

Hi Vintage,

It may be worth considering some of the characteristics of slender deltas.

Generally deltas are regarded as high speed devices but their low speed performance deserves attention too. The important thing to realise is that while a delta operates much like other flying wings at small angles of attack they start to shed large vortices from the leading edge as AoA increases. The resulting low pressure on the upper surface produces lots of lift. Drag does shoot up as the angle of attack gets silly. The flow mixing caused by the vortices make the system very robust and stall is hugely delayed.

I recently built two deltas from depron each weighing about 200g powered by a PJS 300 motor. The intention was to achieve a design that could fly very slowly, manoeuver tightly (and hover) but also maintain the ability to fly outdoors in a little wind. Both versions were very successful although I've a couple of things to fine tune. The second larger version flies nicely indoors and can easily slowed down to a crawl.
Here's my "Depron delta" thread (http://www.rcgroups.com/forums/showthread.php?t=401478&pp=15) in case it's of any interest.

I'm not sure this is what you have in mind but I thought I'd throw it in the pot while we're playing with ideas.
I'm sure a REALLY light delta could easily be built. The compact shape makes it easy to keep the weight down while keeping the structure reasonably rigid. There are however some problems. You'll be flying at high angles of attack to achieve very slow speeds and because of the high drag involved you'd still need a fair amount of power. I'd guess that an IPS on 3s would manage a delta maybe 25% bigger (area) than my lightweight in high AoA and lw AoA flight however the transition might be a problem. Slowing into high AoA flight is easy - you just throttle back and add elevator to stay up. Accelerating on the other hand requires a bit of power to get the nose down without loosing altitude. The high drag at high AoA means you need more power to transition than to fly either fast or slow.

I may try a super-light delta at some point to experiment with some of these characteristics.

Another lightweight contender is a Rogallo wing but I wouldn't expect much by way of breezy weather performance!

Aidan

[vintage1]

That's interesting...no problem with a 3s LIPO setup..those will deliver +50% power over a 2s setup..not rteaslly hover territory on a depron delta, but close.

I never thought about going for high lift high drag setups..

The other similar characteristic aircraft is the autogyro...

[Aio_1]

...The other similar characteristic aircraft is the autogyro...
That's another type that I'm interested in although I've never got around to building one - too many ideas, plenty time, too lazy!

Here's a video by Jurgen Heilig (http://airtoimedia.nl/web/upload/JurgenHeilig/Whopper.wmv) of a light autogyro called the Whopper which was posted in the F3P forum.

Aidan

[Bill Glover]

I never thought about going for high lift high drag setups..

That's what the IFO / Mini IFO is ...

[Mister UHU]

Hi Mr UHU, many thanks for your kind comments!

My little red pylon racer became a plan in RCM&E mag. in 1997 (IIRC).
We raced them every year at Olympia until the show moved away
- one year we had almost 30 of them there!
I built a 4-channel one too with a throttled PAW .55 diesel
and flew that at Olympia as well
(even raced it one year after my Cox one had a mid-air!).
I still have both the models fully airworthy,
my original one does indeed fly as an electric now
with a Speed 280 Race and 7x720 AAA nimhs!


Hi Bill,

Sorry for the delay in my reply.

Glad to hear that you are still building neat models.
Interesting you chose an IFO as your avatar,
I would have chosen one of your own models.
I think your little pyloner had all the things needed to make a classic design.


Getting back to the subject of this thread.

As no one else has mentioned this I will.

During the 1970s RCM&E published some articles by Pete Russell
in his "Straight and Level" column.
Here he described his attempts to make a STOL plane to fly
in and out of his back garden.

He modified a traditional "trainer" type model made from balsa and tissue,
(I think it was a Keil Kraft Super 60).

He added large wing TE flaps,
and some wing LE slats,
to produce high lift at low speed.

In the end I think he got to a 45 degree angle on take off and landing.

As for other attempts at slow flyers,
several people on RC Groups have modified GWS kits,
(Slow Stick ?, Pico Stick ?).
Some more successfully than others.

Vintage : I think you should just go ahead with your first idea,
and make a STOL traditional design model.

In spite of Depron, Carbon Fibre, etc, etc,
balsa and tissue still flies very well.

[bluesky123]

About 20 years ago, I read about a contest for the slowest flying R/C plane somewhere. As I recall, the technical specifications were rather strict: it had to be a conventional plane with the horizontal thrust vector, i.e. the craft had to be hold in the air by the lift generated by its wing. I don't remember if it was a contest for college kids or if it was some kind of grant and several teams competed for getting it. I remember a picture of a guy walking next to a 10-foot wingspan monoplane with a funky thick airfoul...

Boris

[Bill Glover]

Peter Russell's "STOL" designs went through at least 3 versions, maybe 4. The plans were all published in the UK, Gordon Tarling had an electric one with an AstroFlight 05G, 8x3000 NiMH and an 11x7 prop:

http://www.rcgroups.com/articles/ezonemag/2002/sep/walsall/17.jpg

[Aio_1]

Of course STOL and slow speed are not necessarily the same thing!

[mharms]

Here's a slow blast from the past. Flies at 2mph. Talk about light wing loading: 0.22 oz/sq.ft.

"Wisp" thread from 2002:
http://www.rcgroups.com/forums/showthread.php?t=60174&pp=15&highlight=wisp

Unfortunately, most of the photos of this plane are no longer available. Only one I know of is here:
http://www.rcgroups.com/forums/showpost.php?p=1980674&postcount=67

I believe I saw a video of this one (before the links went bad) -- it was astoundingly slow. The "Walker" is another super slow one (however, its a biplane).

Here's the "Walker":
http://www.rcgroups.com/forums/showpost.php?p=1303200&postcount=14

Mark

[Bill Glover]

Of course STOL and slow speed are not necessarily the same thing!

Most STOL planes do have the ability to fly relatively slowly though, pretty handy for short landings!

One r/c club I flew at used a farm airstrip, and one of the full-size there was a Helio Courier. Astonishing plane - in a gentle breeze the landing speed was almost zero (IIRC the stall was around 25 mph).

http://www.aerofiles.com/helio.jpg

[Altocirrus]

Ok, it's not too conventional, but there's always the fanwing idea...

http://www.fanwing.com/frontimage.jpg

"FanWing is quiet, stable in turbulence, and slow. It already achieves virtually vertical takeoff. FanWing cannot stall. Its already established efficiency in lift and thrust makes FanWing highly space and fuel economical."

[Mister UHU]

One r/c club I flew at used a farm airstrip,
and one of the full-size there was a Helio Courier.

Astonishing plane
- in a gentle breeze the landing speed was almost zero

(IIRC the stall was around 25 mph).



http://www.aerofiles.com/helio.jpg


That yellow plane looks about right,
but it can be modified to be be much more extreme STOL.

The Helio looks like it would make a good model.
The photo shows the LE and TE details well.

[Lewist]

I was also going to suggest something similar to the two stol planes above, but taken maybe a little further. I can't find the picture now but i have seen pictures and details on a plane similar to the above but with MUCH MUCH larger 'flaps'.

here is my suggestion.....

a high winged aircraft with an undercambered wing (like the yellow plane above). Have a very large set of flaps on the back that can be rotated to quite an extreme angle, and also have the front of the wing on an adjustable mount, so when the flaps are bought down it raises the LE of the undercambered wing thus creating a large scoop when coupled with the flaps that diverts air downwards.

Couple this with a large prop (DD outrunner) you could gain reasonable forward speed as well as wind penetration, then deply the huge flaps and increase the AOA of the wing to create an STOL plane that can plod allong at a very low speed.

Might be the best compromise to achieve both slow flight and wind penetration.

[Lewist]

Found it...

This will actually VTOL, but a compromise between this and the other planes above might meet the required criteria!


http://www.vstol.org/wheel/VSTOLWheel/Ryan92VZ-3Vertiplane.htm