The Best "Possible" STOSL Aircraft: Lets design it

[Broncazonk]

Hyopothetical question--one that I've been pondering for years. If you were designing a STOSL (Short Takeoff Short Landing) aircraft that would be like a PC-6, or Turbo-Beaver, in size but would be much, much better at STOSL, what would be its design features?

I've been thinking of an "active variable-incidence, parasol wing" that would also feature retractable slats. The wing would be connected to an actuator, the actuator connected to a computerized flight control system that quickly acted and reacted to all the various inputs: delta velocities, sink rates, engine power and performance, prop speed and atmospheric inputs while landing and taking off.

I'm really hoping that everyone will jump in with ideas so we might brainstorm a Superduper-Storch, or Ulta-Maule.

Thanks

Bronc

 

[Hobbes]

The Hunting H.126 showed one possible alternative approach: huge blown flaps.

 

[Nik]

Is there any mileage in the deLanne configuration ?? IIRC it had enviable short-field handling and tame stall characteristics.

 

[AeroFranz]

whatever you do, keep in mind that at very low velocities aerodynamic controls (which rely on V^2) become ineffective. You might end up needing reaction controls like puffers to maintain control.

 

[Abraham Gubler]

whatever you do, keep in mind that at very low velocities aerodynamic controls (which rely on V^2) become ineffective. You might end up needing reaction controls like puffers to maintain control.

Not unless you put them in the slipstream of a propeller.

Bronc, you may want to look at the research of the Crouch-Bolas company in the 1930s:

http://www.secretprojects.co.uk/forum/index.php/topic,3913.msg30856.html#msg30856

(Especially the linked to Flight Magazine .pdf)


They also had a design for a STOL fighter which was similar to that four engine transport but scaled to single engine which was in the fuselage behind the cockpit powering two props via gears and shafts at mid wing. With the low aspect ratio wing and the twin-tail all in the slipstream of the props it had high lift and good control at slow speeds. No doubt you could reverse pitch the props to bring it to a dead stop after a very short landing roll thanks to its very low landing speed.

 

[Broncazonk]

The Best "Possible" STOSL Aircraft: Lets design it

I'm thinking that the Coandă effect and vortex generators have to get worked in here somehow??

Bronc

 

[piko1]

lets add one LHTC T800 Slats, flaps and Boundary Layer Control and max takeoff weight of 3,000kg :

 

[Broncazonk]

Is there any mileage in the deLanne configuration ?? IIRC it had enviable short-field handling and tame stall characteristics.

Yep, after some quick reseach, the tandem wing concept has some very interesting possibilities.

Bronc

 

[Broncazonk]

Lets add one LHTEC T800

I agree with that entirely. I just looked it up and that's one hell of a powerful, high-torque engine.

So would you put a BIG diameter, 6-bladed prop on it? Something like 120-inches in diameter, a wide-cord 6-bladed composite prop?

The almost-tandem wing concept makes a lot of sense--having a very large horizontal stabilizer. Maybe both the main wing and an over-sized horizontal stabilizer would be active/reactive variable-incidence, with the front wing having retractable slats?

Bronc

 

[piko1]

yes big diameter 6 blade prop and we need to achieve low STOL speed minimal empty weight maximizing the payload and this leads us to the composite materials ;D


PS something like this but with larger wing?

 

[Michel Van]

Here my proposal (not new, there were some before me with this )


Twin Wing with big flaps to push wind down

 

[overscan (PaulMM)]

For a jet design - maybe Upper Surface Blowing?

 

[Grey Havoc]

Use the AT-3 (ATTT) as a basis?

[IMAGE CREDIT: Scaled Composites]

 

[Mike Pryce]

I'd nominate the Lockspeiser Land Development Aircraft as the basis. It was designed to be easy to fly and maintain etc. For STOL aircraft (no need for the extra S!) keeping it simple makes sense.

There was a larger version planned (see below), which had partially vectoring prop engines mounted on stubs between the canard and main wing. A little less simple perhaps, but better than blown flaps etc.

http://www.vads.ac.uk/diad/article.php?year=1972&title=278&article=d.278.31


http://www.secretprojects.co.uk/forum/index.php/topic,6305.msg134943.html#msg134943

 

[Abraham Gubler]

I'd nominate the Lockspeiser Land Development Aircraft as the basis. It was designed to be easy to fly and maintain etc. For STOL aircraft (no need for the extra S!) keeping it simple makes sense.

Problem with this plane as a CAS platform is the canard kind of ruins downwards pilot vision.

 

[Stargazer]

Use the AT-3 (ATTT) as a basis?

[IMAGE CREDIT: Scaled Composites]

My thinking exactly...

 

[overscan (PaulMM)]

Some of the Soviet COIN projects look useful in this context e.g.

http://www.secretprojects.co.uk/forum/index.php/topic,50.msg79925.html#msg79925

 

[Abraham Gubler]

The problem with this spec is it includes two very different requirements: STOL and long endurance. STOL aircraft tend to be high drag and therefore difficult to keep in the air for extended periods. Also this aircraft would need to operate from the LHD/LHA platform which does not have much surplus deck space with constant helo movements, is often required to ballast down or sail at low speed for well dock movements (meaning little or no WOD). An aircraft with lots of wings is not going to fit in well on a LHD flight deck.

Some out of the box alternatives could include a long endurance helicopter like the A160 or dispensing with the need for STOL by using unconventional launch and recovery. By using catapults and skyhook you can have a very low drag, high aspect ratio aircraft (even dispense with flaps and gear) that has ZLTOL [Zero Length Take Off and Landing] capability. A giant, manned Scan Eagle?

You can minimize the footprint of the platform by designing it to commercial standards of use via a two mission per day sortie rate. With each mission 10 hours long (one hour out, eight hours loiter, one hour back) with 12 aircraft flying two missions per day you can sustain eight orbits. This would mean your mother ship would need very little footprint to operate the CAS fleet. One aircraft can be on the catapult, one on the skyhook, one being turned around, one in transit and eight in their CAS loiter.

 

[Broncazonk]

The Best "Possible" STOSL Aircraft: Lets design it

I'm trying to invent a new class of aircraft: the STOSL. Everyone knows what a STOVL is, but STOL has various meanings that nobody agrees on. See dicussion here: http://en.wikipedia.org/wiki/STOL

Anyway, I propose that a STOSL (Sto-sul) aircraft should be defined as: Short Takeoff and Short Landing (STOSL) - The ability of an aircraft in a fully loaded condition to clear a 50-foot (15 meters) obstacle within 150 feet (50 meters) after commencing takeoff, or in landing in a fully loaded condition to stop within 150 feet (50 meters) after passing over a 50-foot (15 meters) obstacle.

Although an aircraft like this may have LHD/LHA application, I'm more interested in learning/reading about all the different STOL concepts that I know nothing about.

Think about an airplane about the size of a PC-6 (something with the space to carry 8-10 people) that can get up and down better than a Storch. An airplane like that would allow rural hospitals everywhere to have air-medivac capability. Medivac helicopters are great, but they are so expensive to operate that in rural areas only the big regional hospitals have them. A STOSL airplane would also be useful to special forces operators and military medivac operations, etc.

Thinking bigger, 30-40 and 70-90 place STOSL aircraft would make great regional commuters. Nasa thinks something like that will be important soon.

Getting up and down vertically creates a lot of troube vis-a-vis weight and design and noise and fuel consumption, but if you could come up with something that 'darn near' or 'comes real close' to having vertical capability, I think there would be value in that.

Bronc

PS: The Russians design really cool-looking airplanes. You have to give them credit, they really do.

 

[Stargazer]

Interesting concept and worth defining.

Not quite what you're after yet, but in the same vein as the Beechcraft/Scaled 133 ATTT, there is the Sukhoi S-80:

 

[overscan (PaulMM)]

For the Marines, what about the oblique wing idea? May be a way to combine STOL and performance.

Note that the S-80 takeoff run is 350m, landing 180m, this is still a long way short of what you are proposing.

 

[Broncazonk]

I got to thinking about it and 150 feet over a 50-foot obstacle sound pretty damn ambitious. Maybe too ambitious. So..

A STOSL (Sto-sul) aircraft should be defined as: Short Takeoff and Short Landing (STOSL) - The ability of an aircraft in a fully loaded condition to clear a 50-foot (15 meters) obstacle within 300 feet (100 meters) after commencing takeoff, or while landing in a fully loaded condition to stop within 300 feet (100 meters) after passing over a 50-foot (15 meters) obstacle.

This sounds more realistic. (I'm already chickening out!)

The figures below come from the Pilatus PC-6 website:

Take-off distance over 50 ft (15 m) obstacle (STOL) = 1,444 ft (440 m)
Landing distance over 50 ft (15 m) obstacle (STOL) = 1,033 ft (315 m)

To make this more interesting, we should two track our thinking towards a military version that might operate of a LHA / LDA, and a different civilian version that might be useful for air medivac applications and such.

What would the unassisted takeoff and landing distance have to be to operate off of a LHA / LHD? (That 50-foot obstacle wouldn't be there.)

Bronk

 

[Abraham Gubler]

I'm trying to invent a new class of aircraft: the STOSL. Everyone knows what a STOVL is, but STOL has various meanings that nobody agrees on. See dicussion here: http://en.wikipedia.org/wiki/STOL

Anyway, I propose that a STOSL (Sto-sul) aircraft should be defined as: Short Takeoff and Short Landing (STOSL) - The ability of an aircraft in a fully loaded condition to clear a 50-foot (15 meters) obstacle within 150 feet (50 meters) after commencing takeoff, or in landing in a fully loaded condition to stop within 150 feet (50 meters) after passing over a 50-foot (15 meters) obstacle.

If you want a plane with this kind of performance (or even your less strenuous one) and carrying payload then forget all this groovy wing stuff you need power-lift. The most efficient way to achieve this is to put the wing into the propeller slipstream (aka propwash) to generate lift without wind or forward velocity. Otherwise you will need rockets like CREDIBLE SPORT to get the kind of acceleration needed to generate so much lift in such a short (20-70m) take off run.

One aircraft designed for the same capability is the Crouch-Bolas Dragonfly. It could meet your 50m takeoff via a proven zero wind 15m run with 35 degree rate of climb.

 

[shaba]

a deflected slipstream air craft would fit the bill nicely .http://en.wikipedia.org/wiki/Deflected_slipstream

 

[overscan (PaulMM)]

The Fairchild M-232 (designed by one of the Dragonfly's engineers) was supposed to be able to take off and land in a 500ft clearing with 50ft-high surround.

http://www.secretprojects.co.uk/forum/index.php?topic=6916.0

 

[overscan (PaulMM)]

And... the missing link between them

http://www.freepatentsonline.com/2650045.html

 

[Broncazonk]

What about the CL-84 Dynavert? http://en.wikipedia.org/wiki/Canadair_CL-84 The aircraft is said to have performed extremely well.

The XC-142 also seems to be on point. http://en.wikipedia.org/wiki/LTV_XC-142

There are so many ideas and concepts that were tried (and rejected) before the advent of computerized flight controls, fly by wire, artifical intelligence, not to mention composite materials. I'm wondering what a XC-142 would have been like with computerized flight controls and fly by wire, plus a 15,000 pound reduction in weight due to the incorporation of composite materials throughout the aircraft.

 

[robunos]

The XC-142 and CL-84 both had full VTOL capability...

If you want a plane with this kind of performance (or even your less strenuous one) and carrying payload then forget all this groovy wing stuff you need power-lift. The most efficient way to achieve this is to put the wing into the propeller slipstream (aka propwash) to generate lift without wind or forward velocity.

How about this ??.......................

http://www.secretprojects.co.uk/forum/index.php/topic,6782.msg57596.html#msg57596


cheers,
Robin.

 

[Broncazonk]

Robunos wrote: "The XC-142 and CL-84 both had full VTOL capability." Correct, but perhaps if we surrendered full VTOL capability and was satisfied with STOSL performance, the tradeoffs would be benefical. For a Marine Corps application, all we want to do is get safely up and down off a LHA/LHD in a fully-loaded condition.

No question, a tilt wing does more, has far more potential, than a simple variable-incidence wing.

http://www.youtube.com/watch?v=qzhEmscJRU4&feature=related

I think, but I don’t know enough about this stuff to know for sure, but I think an Intelligent Flight Control System: http://en.wikipedia.org/wiki/Intelligent_Flight_Control_System would be quite important to an aircraft like this. And once in normal flight a Flight Envelope Protection System: http://en.wikipedia.org/wiki/Flight_envelope_protection would also be useful.

Bronc

 

[Broncazonk]

The Do-31 looks like something out of Jonny Quest!

Watch this: http://www.youtube.com/watch?v=x3YueCf1JeI&feature=related

Simply incredible: http://en.wikipedia.org/wiki/Dornier_Do_31

 

[robunos]

Robunos wrote: "The XC-142 and CL-84 both had full VTOL capability." Correct, but perhaps if we surrendered full VTOL capability and was satisfied with STOSL performance, the tradeoffs would be benefical. For a Marine Corps application, all we want to do is get safely up and down off a LHA/LHD in a fully-loaded condition.

This was the point I was making, the XC-142 and CL-84, being fully VTOL capable, are too complex and highly specified (and expensive) for your application, whereas the Bell Hybrid Tandem Rotor is more simple and seems better suited.............
I think the trick would be to limit the wing tilt angle to a degree below that which 'normal' aeroplane-type controls become ineffective. This should remove a lot of the complexity and cost.


cheers,
Robin.

 

[Abraham Gubler]

Bronc if you think a conventional helicopter is too expensive for your requirement then you really shouldn't be barking up the tilt-wing or vectored thurst and lift jet tree. Tilt wings are as expensive to build and fuel hungry as helos and any VTOL jet thrust lifter literally gets into the air on a giant cloud of burnt fuel-dollars. The Do 31 is very cool but never cheap. Perhaps a low cost VTOL, efficent cruise option is to look back at the tip powered, compound helicopter: the Fairey Gyrodyne.

 

[sferrin]

Bronc if you think a conventional helicopter is too expensive for your requirement then you really shouldn't be barking up the tilt-wing or vectored thurst and lift jet tree. Tilt wings are as expensive to build and fuel hungry as helos and any VTOL jet thrust lifter literally gets into the air on a giant cloud of burnt fuel-dollars. The Do 31 is very cool but never cheap. Perhaps a low cost VTOL, efficent cruise option is to look back at the tip powered, compound helicopter: the Fairey Gyrodyne.

DARPA Heliplane was looking at that. The biggest problem was noise, noise, and more noise, from the tip-jets. (Of course the two main companies working on it suffering financial devistation didn't help either.)

 

[Broncazonk]

Bronc if you think a conventional helicopter is too expensive for your requirement then you really shouldn't be barking up the tilt-wing or vectored thurst and lift jet tree. Tilt wings are as expensive to build and fuel hungry as helos and ...

No, I'm sorry, but that won't do. I want incredible performance and capability, but I don't want to pay for it. I'm fairly certain there is a free lunch out there somewhere if we search hard enough for it. B)

It's time we turned aircraft development around people. Right now it's like standing in a wind storm shaking bags of $100 bills on the ground. I think we need to talk to the F-35 people, they seem to know everything that we never want to do... :-\

Bronc

 

[SteveO]

Does the LTV Atlas fit the bill? http://www.secretprojects.co.uk/forum/index.php/topic,170.msg119602.html#msg119602

 

[Broncazonk]

I'm struck by how many interesting ideas and possibilities were ruled out prior to the advent of composite materials and computerized FCS.

Bronc

 

[AeroFranz]

Can you elaborate? Neither composites nor FCS are enablers of new configurations per se. They might make for a better payload/range aircraft, but they are not design drivers for STOL of the same level as, say, CLmax.

 

[piko1]

easy to use easy to maintain it can achieve the Specs easy
in two words back to the basics
http://en.wikipedia.org/wiki/Fieseler_Fi_156_Storch

 

[Pioneer]

What about the CL-84 Dynavert? http://en.wikipedia.org/wiki/Canadair_CL-84 The aircraft is said to have performed extremely well.

The XC-142 also seems to be on point. http://en.wikipedia.org/wiki/LTV_XC-142

There are so many ideas and concepts that were tried (and rejected) before the advent of computerized flight controls, fly by wire, artifical intelligence, not to mention composite materials. I'm wondering what a XC-142 would have been like with computerized flight controls and fly by wire, plus a 15,000 pound reduction in weight due to the incorporation of composite materials throughout the aircraft.

I agree Bronazonk!!

I think in the case of the Dynavert - as you have stated, 'it performed extremely well' Perhaps too well for the U.S Navy's liking, whom I assume was just as happy at the time to kill off anything to do with or associated with the Sea Control Ship (SCS) program, which as everyone is well aware was seen as a threat to the Navy's 'super carrier'

As for the XC-142 - The use of composite materials - I would think would have especially in the wings, take out a lot of that bounce and flex (which I have seen in some trial videos), which looks both fatigue stressing and dangerous! I have read somewhere that it was this wing flexing which contributed problems with the inter-engine linkage system!
Out of interest how did you derive 15,000 pound weight reduction through the use of composites?

In any case I wonder how they might tackle the complex wing-folding arrangement of the XC-142 today, which was itself a nightmare and would have added greatly to weight, complexity and cost!

Regards
Pioneer

 

[Broncazonk]

If I am not mistaken--but I hope that I am--a major unsolved problem in composite materials engineering is the interface between titanium and aluminum--most metal components--with an plastic or epoxy matrix. The coefficients of expansion are dramatically different between materials AND both titanium and aluminum are difficult to bond because of the oxide that forms on their surfaces. If this problem could be solved, carbon fiber + titanium and epoxy or PEEK/PEAK/PEI plastics could be synergized together in very new ways.

We could go to 85% plastic airplanes right now, but the engineering community has decided not to trust them--can't predict cracking in epoxy bonds quite yet, though PEEK plastic with long-strand carbon fiber is incredibly strong. (Difficult to manufacture, but 100x easier than building them rivet by rivet.)

Bronc