Extreme STOL/VTOL homebuilt

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by BBerson, Jun 18, 2008.

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  1. Jun 18, 2008 #1

    BBerson

    BBerson

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    I have been considering the idea of an extreme STOL homebuilt. This is my plan:
    Start with a conventional light or ultralight airplane and add one or more lift fans to provide direct powered lift. This powered lift system would only be needed briefly for takeoff and landing just a few feet above the ground.

    Start with a small amount of lift, then gradually add more lift fans for extreme STOL. Then with enough lift eventually VTOL might be possible but start with STOL first.

    Any ideas for powered lift fans that could be used for brief thrust of a few seconds?
    Stored energy was suggested in a previous thread. JATO works, but is not practical for a civilian, I think.
    Any other thoughts appreciated.
    BB
     
  2. Jun 18, 2008 #2

    Tom Nalevanko

    Tom Nalevanko

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    So if you use the fans to get off the ground, now what? You still have all that aircraft mass to accelerate to a speed where the wings provide enough lift. Rubber tires on the ground might get you there faster if you could get a lot more lift out of the wings at a slower speed. On landing you have the reverse problem.

    But there are examples of your idea. See the pix I took at the Camarillo Air Show a year or maybe two ago...
     

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  3. Jun 19, 2008 #3

    BBerson

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    You are correct, I left out part of the explanation...
    The lift fans need to be on a swivel similar to your photos. The fans would be tilted up and forward for takeoff or up and rearward for landing. The pilot could choose the angle depending on weight and altitude.

    So for instance, an ultralight that normally lands at 28mph might be able to land at 20mph with 50% additional lift from some light fans. But the big advantage at landing is the reverse thrust component used to slow the landing even before ground contact and before the brakes are usable. This is how birds land on a branch. I don't want to come to a complete hover because that requires much more control devices. And I think this STOL type assisted landing would be almost as useful as a helicopter but safer and simpler.
    Same thing for takeoff but with more forward thrust and lift the takeoff would be short but not vertical. Maybe a future version could be vertical, but that is too much to bite off for now.
    BB
     
  4. Jun 19, 2008 #4

    Tom Nalevanko

    Tom Nalevanko

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    Why not give Robert Parker a call about his plane and possibly report back to the group? He might sell it to you for a really good price... Good luck in your design.
     
  5. Jun 19, 2008 #5

    Tom Nalevanko

    Tom Nalevanko

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    Ooops it is Roger Parker and no, I have never met him although he lives fairly close to me. He is not in our local EAA Chapter. A lone wolf going vertical...
     
  6. Jun 19, 2008 #6

    Holden

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    BBerson,

    You put the prop in front. Make the prop 8-10 ft in diameter, make it 8-10 inches in chord, variable, turn it at 1000 (cruise power)-2000 (short term power) rpm and at best L/D. Make the wing a double delta shape with LONG chord, with flaps, with square wings outboard that are freewing with coupled elevators that control AOA.

    This makes the flaps a thrust vector device keeping the cockpit flat to max 30 degrees AOA and in cruise the prop runs quiet and slow and at max L/D. The freewing makes it stall proof (roll control) and easy to fly into high AOA with power on giving dynamic air to the wing. Blow the delta and freewings with stored compressed air from the spar for touchdown to get cls in the range of 4 with dynamic air, yielding touchdowns in the <15 mph. That is the solution I am doing in part.

    The delta shape is critical (I have wind tunnel data I did on a model, so I have some experience with it). The airplane will be high and low speed capable by 10+ times low speed, whereas the typical flower flap stuff get you no more than 3 times stall to cruise speed ratio. This is critical for a smooth ride in turbulence making it useful in any condition.

    Under all this, and most important, is a high energy landing gear. A flare is NOT wanted at this point to avoid high wind loss of control.

    There you have it...
     
  7. Jun 19, 2008 #7

    Tom Nalevanko

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    Sounds like an interesting idea. Not sure what a double delta is though... Like the Draaken?

    While the high to low speed ratio is important, the absolute speeds cannot be neglected. I would argue that for general STOL work a 6 to 1 with stall at 40 knots and cruise at 240 knots would be much more desirable than one at 15 mph to 150 mph. The era of the bushplane is over! Most all STOL landing spots are within several hundred miles of an improved strip with road access or services like fuel. So if you can do 240 knots and have 4 hours autonomy; you can go out and back 500 nautical miles. That pretty much covers the world. I hope to show this on Google Earth sometime later this year. There are other considerations which favor a high top speed like time in the air, both for pilots but also for passengers who may be sick or become sick.
     

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  8. Jun 19, 2008 #8

    Holden

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    Tom,

    So, make it "stall" at 45 and go 450! Am I missing something here? That 15 mph could also top out at 250 kts just as well with the right power and provide a smooth ride. Double delta with freewing IS the smoothest ride out there.

    I think that flight "progress" will be in local micro/neighborhood airports built into parks or subdivsions, or even on the side of the road. We have interstate freeways with "airport" spots at each exit if you follow my train of thought. I can beat your 250 kt machine with a 125 kt machine any day "door to door" when I don't need the airport, inspection time, etc. , support car and all that junk.

    Airports are obsolete and must become obsolete before flying is affordable and useful. Speed cost money.

    500 miles is useless in the daily life of a person. I am talking about using it as a primary vehicle, not a "for the rich guy with a limo weighting with a driver crowd who is off to a glowball meeting with VIPs." I am suggesting doing it at less than 2 cents/mile.

    Your vision is old, well tried and useless for 99% of the world, and with fuel at $5/gallon, it seems outdated in a world that wants the USA standard of living. Natural Gas is 6.5/deca therm or $0.78/gallon equivalent of gasoline. We have 20,000 years of NG in the Gulf of Mexico alone. The planet produces it yearly many times more than what we could ever use.

    A Boeing airliner gets 60 mpg per passenger. My airplane will be around 50-70 mpg and with two people, or six for that matter, it will make the big guys obsolete. This is the future, not bigger and faster. Seldom do I ever need to go 500 miles.

    We have not learned to fly until it parks in your home garage and it can land just about anywhere, especially at Wal-Mart. The reason Boeing does not do what I am talking about it is because it is HARDER to do than big. I was offered a Level three engineering job on the Dreamliner and I turned it down...why? Buses are outdated, Socialistic in nature, and have little respect for a person's time. My schedule MUST be flexible and a bus schedule it so much a joke to a "freeman" or American at that.

    I think most of the problem in aerospace is a problem of vision, which is not wanted in corporate America, not smarts. They are all trying to build the latest Titanic (Airbus 380, 747) and forget about the individual who needs to get around. What about an airplane you can ware on your back and stow under your desk at work (when you need to show up once a week). That is the future, not this junk the mainstream focuses on.

    Real estate is about location, transportation to the location, transportation, transportation. The best place to live is on the top of a mountain...if you can commute there... I have zero uses for buses, airports and the like, anymore than taking a train.

    later,
     
  9. Jun 19, 2008 #9

    WileEZ

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    Sounds like a gyrocopter will fit the bill nicely.
     
  10. Jun 19, 2008 #10

    Holden

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    Wilez,

    Great comment.

    No, one will NOT work. The large swinging blade is very offensive in tight areas and the drag is many times more per load ability, not to mention speed limited.

    Groen brothers from SLC have tried it without success. Carter copter has also made a combination system, and have not had success.

    The skill level is much to high for the average person. Rotor speed management and such is just so much to go wrong. Most have the rotor too high for a garage.

    The rotor is a poor way to generate lift at hight speeds and the maintenance is very high. Clearly nobody has been successful with them for the last 50 years.
     
  11. Jun 19, 2008 #11

    Jman

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    Call me a pie in the sky kind of person but I do believe the next big leap of engineering will come from the garage, not the corporate boardroom. Money and power seems to stifle creative thought in many cases. Design by democracy I think I heard someone else say. That being said, it's easy to get jaded by the continuous onslaught of promised breakthroughs of homebrewed unlimited power that never go anywhere. I'm still hopeful though...
     
  12. Jun 19, 2008 #12

    divad_strebor

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    Have you ever been to Australia? You can fly for a lot of hours and not come close to a bitumen strip in a lot of areas.. That, and STOL aircraft are regularly needed to get in and out of areas that are completely inaccessable by road in emergency situations. They are needed DAILY. Not just every once in a while...

    Holden, I'm all for progress, don't get me wrong... I'm watching with great interest the development of diesel technology in aircraft. I agree, it is too little too late, but it IS progress, and ANY progress is good progress. What you're saying in this and other posts is that we should abandon ALL aircraft development of ANY kind and start developing hover cars (an interpretation). What you appear to be looking for is an "engineering dictatorship" of sorts.

    You have a great dream, and hopefully a goal on where you want to go in aviation, and I hope you can keep the vision alive and maybe someday achieve it, but in the meantime, don't declare every other idea and design as "useless", "outdated" and "a waste of time". The world is not going to stop turning just because you have a dream. Saying tried and proven designs are useless to 99% of the population may be true to some extent... 99% of the population are probably not the least bit interested in aviation. Did you know though, that 74.6% of all statistics are made up on the spot?

    As a 1%er (to use an old outlaw biker term) I'm going to thoroughly enjoy designing, building and flying my "cub clone". Just like the majority of other homebuilders out there.

    - Dave Roberts.
     
  13. Jun 19, 2008 #13

    divad_strebor

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    Oh yeah, to get back on topic... I think starting with an existing ultralight is probably not the easiest way of doing this. It will mean that you will be building a lot of compromise into it. As I'm sure Orion would say, it would be better to start fresh, and design it specifically for the purpose. Take compromise out of the equation right from the word go..

    As a practical example, I used to buil hotrods for a living. I found that in the vast majority of projects I was involved in, any "little" modification, usually intruded on some other component and required a LOT more thinking than previously anticipated. There was one car that truly stood out from all the others as NOT having this problem, and that was a GT40 kitcar that I did some work on. AFAIK, the kits are very similar in construction to the original cars that ford produced in the 60's.

    The requirements of the car right from the beginning was that it was to win races. This meant it needed to be powerful, with good suspension and brakes, well balanced and LIGHT WEIGHT. I'm sure they had some class rules to comply to as well, and these probably would have determined the engine used. And this is where the design began. They started with a flippin big V8. Then designed a race car around it. No extra bits like wind up windows and power steering or even carpeted interior for that matter. Just pure race car. Converting road cars to be race cars is a bit of an uphill battle, because everything is built on a compromise. Everything I touched on that GT40 kitcar just "fitted". Have I illustrated my point sufficiently? I feel like I've just added confusion to the issue.

    I guess what I'm trying to say is, if you were to retrofit lift fans to an existing design, where would you put them? And what structure (ie: spars, etc) will they intrude on? And what extra structure will be required to support these fans, as well as substitute structure that was in the way of them? All of this = extra weight that COULD be designed out if you start with a clean slate.
     
  14. Jun 19, 2008 #14

    rtfm

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    Well done, Dave. Excellent post.

    What we need both on this forum and in aviation generally, is a healthy mix of brash innovation and wise conservatism. And no, I don't think the two are antithetic. They are on opposite ends of the spectrum, but it is the same spectrum.

    Part of me thrills at the sometimes abrasive expostulations of guys like Holden. Good on you, mate. We all need to confront our comfortablenesses. But another part of me is quietly satisfied with the conservatism and world-wisdom of some of the other posters here. Could we be more adventurous in our thinking, design-wise? Of course. Should we eschew things simply because they are tried and un-new? Of course not.

    Real advances are seldom if ever the result of radical departures from history. More often than not, the first glimpse of a new landscape is had by standing on the shoulders of those who have gone before.

    Having said this, I think that decrying the best efforts of honest and talented people because we disagree with them is mean-spirited. You can do better Holden. My suggestion would be to design something wonderful first, and then rail against the rest of us. That at least would give your words some weight.

    So c'mon mate - blaze the trail. If you build it, they will come...

    Regards,
    Duncan
     
  15. Jun 19, 2008 #15

    divad_strebor

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    Oh, and one more thing... Take careful consideration in regards to your powerplant(s). There would be nothing worse than having the noise stop when you are in alpha configuration 50 - 500 feet off the deck. There would not be many (if any) options available to you in this situation besides "stick your head between your legs and kiss your a$$ goodbye".
     
  16. Jun 19, 2008 #16

    Dana

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    Holden sounds almost as starry eyed as Moller... and 30 years and millions of investor dollars later, Moller still hasn't changed the world with his "everyman's" flying cars.

    It's possible to design a good STOL plane. It's possible to design a fast plane. But try to combine the two and you have a compromise that does neither well. The design requirements are contradictory. Ditto for roadable planes.

    As for micro / neighborhood airparks, never happen. People will be screaming about the noise even before it's built, or they'll build a new house right off the departure end of the existing runway and then get the airport shut down because of the noise. It's hard enough way outside of town.

    Now, I'm all for progress, and there certainly is room for improvment in current aviation technology, but when you put too many revolutionary ideas into a project, and the project dies because one critical compenent doesn't pan out, the other good ideas get lost.

    -Dana

    "Makers of oils will assure you their lubricants will last the life of the transmission. This may be true, but that life can be longer if you change the oil."
     
  17. Jun 19, 2008 #17

    BBerson

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    Lots of interest, that great.

    Any discussion about VTOL is likely to include the crackpots and investment fraud schemes such as Moller. I feared that.

    That is why I proposed what I think may be a more practical goal, a gradual improvement in increments.

    There are plenty of aircraft in the speed range of 28mph and faster. But nothing practical in the speed range of 15 to 28mph. A true hover is not really needed, so why start with a VTOL and fail?

    Dave,
    I meant, start with an existing light design that is optimised for the purpose of adding lift fans in increments for experimenting. Not an off the shelf ultralight. I agree with you, there would be much use for a super STOL bushplane.
    There is plenty of room for innovation, the field is wide open for ideas. Nobody has anything in the speed range of 15 to 28mph.

    I need a practical powered lift device. I think the small electric motors might be the best because they are instant on or off. Like the RC giant scale planes are using. But I only need a short burst of power and batteries are not good for that. Maybe ultracapacitors?

    This is a project for the future, I need to build the optimised airframe first.
    BB
     
  18. Jun 19, 2008 #18

    Holden

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    I just love the comments I get from these "homebuilt sights. If a guy states his vision, you piss on him and then pull out the incremental bull crap thing. No development of a discussion. Then they call me some Moller guy even though I fund it all myself and have never asked for ANY funding at all, nor would I accept any if offered. I am one of maybe two (me and who I don't know) on this group who have actually gone through wind tunnels and scale modeling, composite prototype build of an actual new concept that got a patent (rare in Aero), and know very well what it takes, but no, you are all experts. Why state it? I state my vision to gage whether I am on the right track...full steam ahead! Thanks guys.

    Hmm.. To get to where I want to go, I can do it in one shot by turning my brain on and using engineering, or I can take 100-200 years to do it in increments, which would require me finding the fountain of perpetual youth first (I have 20-30 years if I am lucky left). This is why people go to engineering school, and those who have not, or don't have a clue how to engineer after getting a degree, turn to increments, taking one step (guess) at a time, which usually leads back to old designs, which is what 99% of EAA types do. Progress is near zero.

    Hmmm Jet engine...how long would it have taken to evolve from a piston to a turbo engine? Seeing that one is a batch processor and the other a continuous process...different cycles...flows... Gee...2 maybe three lifetimes? If that bridge could ever be found...Can one of you, just one, map out an incremental path to a turbo jet from a piston crank step by step and estimate the decades it would take if you built each step, tested it, flew it, and "proved" it out, just like you all suggest? Oh, you cannot know a jet engine exists...ah...well, since you know the answer after the fact, and the guy with his brain on who invented the jet engine did not know, you have the answer in front of you. Explain how the jet engine inventor got there with guys like ya all pissing on him, and did it during a war? Oh great men of increments...Please inform me. :))))

    As for actually answering the BBerson poster's question, it looks like I was the only one who actually did. You want a stol machine...Do what I said. I can build it in one year or less...using a lycoming, Rotax, Hirth (got one of those in my shop just waiting...)...but why waiste my time?

    Think of it this way. You want to design a human being. You need a lung, liver, heart, *****, brain, glands, eyes, finger, ****, butt, and on and on. Lets say you want to build it in increments and leave out the heart...what happens? Dead on arrival. To make it live you need the whole package. The same, to a much lesser extent, applies to airplanes. Try to build a car today and leave out airbags...good luck on getting on the road in production.

    So, put another way, the mission requirements entails certain things, and without them you will not get to high volume profitable production. According to Wall Street no aero company since the Wright brother has made a profit, except Southwest Airlines. Hmmm. Lots of smart guys, and not one made a real world, non governmental supported profit long term when you figure in real world liabilities (massive). Not Piper, Cessna, Douglas, Boeing, Burtan, Airbus, Vans, Lancair, and on and on. You have your savings and you want to get it right the first time because starting over from bankruptcy (the rule in this industry) makes life less than ideal.

    What are those requirements? All I get from you guys is bull and zero adding to the picture, which is in my book about as negative as it gets... But, hey, I am the negative guy for dealing with reality of an industry that is the worst place to put money (zero profit) and only alive because of massive government handouts.

    No, I am not looking for a dictatorship, just a clear vision of what needs to happen. By asking, I show respect for your opinions. If you have a better vision, then, please explain it. If your vision is the same as what has happened since 1903, no thanks. It will bankrupt me...and men with 100 times the money I have.

    I guess hope runs eternal. After not visiting this group for 4-5 years, I thought there might be someone out there who actually wants to innovate and discuss. My finding is that 99% of EAA guys have zero, in fact, massive dislike for innovations. Nobody in my EAA chapter could care less, except one guy, who crashed his scale model (which I told him would crash), but he still refuses to see a better vision and work with me....

    If you happen to know of anybody, let me know. It is like finding a needle in a hay stack...
     
  19. Jun 19, 2008 #19

    WileEZ

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    A thought:

    I read years ago, on some experimental high speed research planes, they had a series of holes just aft of the leading edge of the wings to blow compressed air rearward over the wing, thus improving lift for STOL capability. IIRC, they were using the exhaust from the engine (turbine?) as the source.

    So what about burying a pipe forward of the main spar, installing small jets in the pipe to direct the compressed air rearward over the wing. The pipe will have to be sized large enough to handle the volume of air needed. The pipe can be stepped, i.e.: large pipe near the root, then progressively smaller toward the wingtip to save weight.

    The compressed air can come from a tank sized to provide enough air to accomplish the mission in very short take off and landing. The tank can be recharged either on the ground or while cruising by a compressor driven by the engine via an electric clutch (like the AC in automobiles.)

    I see that some light airplanes use tube spars fore and aft with the ribs in between. The forward spar can do double duty as the compressed air pipe to save weight. Or one can use a pipe in place of the strip I see connecting the forward ribs at the leading edge of the wing.

    The tank can be aluminum or even fiberglass. One will have to be careful not to exceed the nominal PSI rating of the tank and make sure the tank is large enough to supply the compressed air requirement before falling below a certain pressure point.

    The tank could be incorporated as part of the rear fuselage thus saving weight.

    Alternatively, use both the exhaust from the engine along with the compressed air to extend the time available for STOL.

    Another alternative. Use wastegate equipmented turbochargers driven off the engine exhaust, only instead of turbocharging the engine, use the compressed air over the wings instead. Wastegate is used to turn on/off the effect. I suggest using one turbocharger, or combining the outputs in a dual turbo setup into one common point to insure both wings get the same amount of compressed air.

    Or any combination of the above, along with other unspecified ideas.

    I can think of many different ways to do this. I expect you guys can come up with the same thinking or more.
     
    Last edited: Jun 19, 2008
  20. Jun 19, 2008 #20

    WileEZ

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    Holden, don't give up hope! I saw your post above right after my recent post. I agree, it's easier to criticize than to contribute. I like to think of myself as a maverick thinker too, but I don't say much due to the "naysayers".

    I have a few thoughts and ideas also, and I will post them after I work through them a bit.

    Keep on posting here Holden.
     

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