Hiller Flying Plateform Planning, All Ideas Highly Appreciated, Aircraft Noob

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protomate

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Feb 27, 2011
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If you already read this, or might of responded, please disregard. I think this may be a more appropriate area for feedback and inspiration.

I am fascinated with the Hiller Flying Platform. I am too scared to go 1000's of feet up, and would just like to stay within 5-10ft of earth to start. Also, with a machine like that, I can play with it wherever I go, and also drive it around most areas from my house (lots of wide open space).

I am not sure this is the ideal forum for this project, but I have been steered here from numerous searches on the project. It may be redundant, as I may ask for help somewhere else on the forum, but I will lay out where I am at right here. Please don't be mad if I ask elsewhere as well. Here is what I have found so far:

Personal Flying Platforms Produced To Date:
1) 3 Hiller machines. 5-8ft coaxial props
2) Hummingbird platform
3) "The Winged Self" by Ben Blakebrough

I would love to buy/obtain plans/prints for comparison for any of these. Can't find them anywhere! Please help direct me to specifics. At this point I am thinking:

1) (2) 5ft props 2 blade running coaxial in a ducted fan arrangement. Not sure what pitch, speed or the space between them that will work well? Where to buy or to build? Not afraid of making from wood as I assume the Hiller ones were, but would like to decrease mass. I am not familiar with carbon fiber at this point. Any ideas?

2) (2) Kawasaki 440cc 2cycle air cooled engines-Perhaps dual custom exhausts for greater efficiency and weight savings. Issue becomes it makes transmission complicated because they both would run clockwise. Would also run redundant belts, and rachet drives in case one fails during flight.

Need to instigate other options. Seems original Hiller design used (2) Nelson H-59 engines 44hp@4000rpm. Seems first Hummingbird used (4) Hirth F33-15A engines 28hp.

I would love to use "certified" aircraft engines, but not sure if budget can handle it at this time. At this point in time, my intention is to go no high than I could fall with a helmet on. Maybe in the future high altitude runs would be attempted, but not until safety systems are tried and confirmed.

Any ideas to source engines? Ones that can be easily configured to run CW or CCW? I would love to use 4 cycle units. Also have to look at maintenance cost. I think from what I read they need to be rebuilt every 100hrs? Seem correct?

3) Frame: Tubing to be high grade steel if possible. I don't really care for aluminum due to its cyclic fatigue properties, but I have to do the design math on this one. All welded joints to be tethered in case of joint failure. Ducted fan shall be tubing, foam covered, then coated with fiberglass, kevlar, and carbon fiber. I wish this unit to be capable of water landings, so the foam can only help.

4)Safety Thoughts(please, please give me direction here as I am sure I didn't consider everything):
a) redundant drive belts
b) redundant motor ignition systems
c) entire blade area will not permit adult sized body parts near them, nor trees, shrubs, large rocks, leaves, animals, parts of the vehicle from a crash
d) altimeter, GPS device to measure speed and route(may just use my Iphone for that) Got an App for that! : )
e) Energy absorbtion system to act from height of 10ft, math to be determined. Need to find figures on how many G's a normal human can handle through there spine. Any direction to such studies?
f) Marker lights for twilight runs. Is their an accepted standard for this like for marine vehicles (red and green)?
g) Horizontal impact absorbtion system. Able to survive a direct hit from 10ft in case this things goes off balance, or if a tree, house, or other non movable thing is hit
h) Fuel system: Max 5gal(ultralight rule correct?) Emergency cutoffs. Crash proofs fuel stores. Safety delivery system.
i) All electrical wiring to satisfy DOT and/or FAA regulations. Redundancy wherever possible. I learned long ago from making CNC systems about vibration and bending duty wire.
g) (2) fire extinguishers, first aid kit, flare gun
h) signalling horn should I become tangled of in a traffic jam, or want to alert others of my intentions

I) self engaging redundant fuel pumps in case
J) Helmet! Any ideas on a good source of resonably priced units for avaition?
k) Parachute that launches by its own power? Not needed at this point, but in attempts at higher altitudes. Any good direction on these guys and gals? I have seen these co2 driven ones I think. Need to budget the weight into design
l) batteries, non spillable type. Fire protected. Redundant task
m) Lighting system of some sort. Possibly white LEDs
n) engine status panel
o) fuel gauges
p) possibly fuel pressure status-cost/weight dependent
q) Propeller drive bearings....Is their a rating system, pm schedule for these?
r) belt pm schedule...Std hrs for this?
s) engine hour meters
t) crash deforming driving pod
u) redundant throttle system. Not too trusting of such linkages based on past motorcycles, jet skis, and atv experiences

Thoughts, Ideas, and Questions for my build:(Please,please share you thoughts and experiences):

1) system to maintain a commanded altitude, manually override able of course

2) Horizontal propulsion system, as I dont expect by leaning to go over 20mph. Read of some machines having the capacity to go 60mph. Seems a bit scarry at 10ft, but to be considered in design

3) gyro to maintain heading, overidable of course. Have seen such a system on RC helicopters, could probably work here

4) Parachute for entire machine, like the ones for tanks in air drops

5) Using several ducted fans around the periphery for lift, even if it is less efficient. This rig is not so high on creature comforts, as you have to stand while operating. For future designs, I could see 2 passagers or more, however instead of end up with a clumsy 20ft diameter craft, I would much prefer to have an elongated craft with a seat or two

6) GPS auto pilot as the RC UAV do. I have had a long look a Guai craft. Would be nice to be able to tell the machine to go pick up its passengers. Don't see why it can't be done as these RC machines can.

7) Sensors to detect path obstructions, potentially feeding back to auto pilot planner

8) Transmitting cameras like the UAV's have

9) Electric drive system. I know it seems crazy, but if you look at the power to weight ratio's of the RC brushless motors w/ controls and batteries, it can certainly be done. Have not yet found a cost effective battery source. The Lipo batteries I use for a few of my RC copters are called 1s. They are 3.7v and 130mah. Tiny and very powerful. I am almost certain that with enough to drive a 70-80kw is would be awsome, but the flight time very limited as the power density still is not as high as gasoline.

10) Emergency radio. I know the max fuel capacity is 5gal for ultralights, but that can get me far enough out their to justify the radio. Also, cell phones can not be trusted everywhere round here. If I crash, and unable to walk, need to call for help. I figure my range to be around 30-60 miles on the fuel.

11) Pulsejet, or similar drive?
I have no experience with them, but I understand them to be ridiculously loud. Even the videos on Youtube hurt my ears, but can these be used to lift such a platform? I have seen 100lb thrust plans on the internet. Could I use 4 or 5 of these to lift a future craft? Can I design a system of noise cancellation? Can they be suppressed? I am somewhat familier with the noise cancelling technologies for automobiles and jet aircraft. I am pretty sure with time and money to driver at least would not have to deal with the noise.

12) Thrust fan noise suppression system. Can the principles of multi order band with enclosures somehow be applied? Can some sort of wacky multi pitched "outside the box" tech be developed to drive such a machine?

I think that is enough about my project for now, as we just met! I welcome any feedback, direction(especially to blueprints of the previous machines), experience, lessons learned, things I haven't thought about that I should? I knew I should of paid better attention in fluid dynamics class

Thanks you everyone! Glad to be here,
Sincerly,
Ben
 

BBerson

Light Plane Philosopher
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My thoughts:
First, you need a design with more thrust than takeoff weight. Not simple, work on that.
Second, you need control. This might be simple in a Hiller platform.
Third, don't worry about a horn (for now or ever). Is this a joke?

Fourth, it is best to ask one question at a time.

Last comment: I like the 5-10 foot flight plan. But to be useful, some new scheme to provide safety at altitude is needed.
Bill
 

Dana

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Ben, welcome! You've picked an ambitions project. Not impossible but very difficult. Some random thoughts:

5' props, even counterrotating, probably won't do it with 40HP (or whatever it is depending on what flavor of Kaw 440 you're thinking of. You'll need to be bigger. Think helicopter rotor diameter.

If you want two directions from two engines, just mount them opposite... one up, one down. One drives from the top with a long shaft, the other drives from the bottom with a short shaft. The old Paraplane used the same approach for counterrotating props. But if you're talking redundancy and overrunning clutches, they have to drive together with a gearbox to give the opposite rotation.

Welded steel structures have a long successful history. No need to tether in case of joint failure.

Don't even to start to think about instrumentation, autopilot, lights, etc., before the technology is proved out.

What you're describing is very unlikely to be an ultralight.

Ballistic parachutes are quite common these days. Usually rocket propelled, they require at least a couple of hundred feet to deploy.

Forget pulsejets and such. Besides the noise, they run literally red hot (naw, that wouldn't be a fire hazard!) and have limited if any throttability.

Electric motors are wonderful. Batteries, unfortunately, are not.

Ducted fans in a low speed application are gonna be loud no matter what you do.

-Dana

Anyone who cannot cope with mathematics is not fully human. At best he is a tolerable subhuman who has learned to wear shoes, bathe, and not make messes in the house. - RAH
 

autoreply

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124d28983fc1317821c9de5d7e352546.png

That's the ideal power from a rotor/prop. Taking into account total efficiency, it is usually closer to twice that (50% total efficiency).
5 feet diameter gives you 20 sqft rotor area, 8 feet gives you 50 sqft. With a thrust/weight of 400 lbs we're looking at respectively 40 and 25 kW. Figure in real-life losses and we're looking at 80 and 50 kW, or 105 vs 65 HP.

There's a reason helo's have large props/rotors:
VTOL_DiscLoad-LiftEfficiency.PNG
 

protomate

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Thank You Bill!

Below are my current thought's, perhaps wrong, but current!

(4) I will only ask one question at a time as I re-read my opening ramble, and saw the complexity of answering it.
(2) The main reason I am so interested in the Hiller, is as a starting point its simplicity, and low altitude hovering potential seem well suited for a test bed for more complex future ideas. IE: I can survive lots of 5ft crashes while I learn. I have fallen from much higher heights (flat on my face)on my stand up jet ski lots of times at very high speeds.
(3) Partially joking about the horn. My thought was perhaps I could get away driving this thing in more urban areas if the engine could be 4 stroke and the blade noise could be somewhat suppressed. One of my other hobbies is acoustics. Maybe, did not study the acoustical behavior of a ducted fan yet. Not even sure where to look......
Last...I have done some reading about air bags for low altitude flight. Definitely plan to pursue that idea
 

protomate

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Messages
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Ben, welcome! You've picked an ambitions project. Not impossible but very difficult. Some random thoughts:

5' props, even counterrotating, probably won't do it with 40HP (or whatever it is depending on what flavor of Kaw 440 you're thinking of. You'll need to be bigger. Think helicopter rotor diameter.

If you want two directions from two engines, just mount them opposite... one up, one down. One drives from the top with a long shaft, the other drives from the bottom with a short shaft. The old Paraplane used the same approach for counterrotating props. But if you're talking redundancy and overrunning clutches, they have to drive together with a gearbox to give the opposite rotation.

Welded steel structures have a long successful history. No need to tether in case of joint failure.

Don't even to start to think about instrumentation, autopilot, lights, etc., before the technology is proved out.

What you're describing is very unlikely to be an ultralight.

Ballistic parachutes are quite common these days. Usually rocket propelled, they require at least a couple of hundred feet to deploy.

Forget pulsejets and such. Besides the noise, they run literally red hot (naw, that wouldn't be a fire hazard!) and have limited if any throttability.

Electric motors are wonderful. Batteries, unfortunately, are not.

Ducted fans in a low speed application are gonna be loud no matter what you do.

-Dana

Anyone who cannot cope with mathematics is not fully human. At best he is a tolerable subhuman who has learned to wear shoes, bathe, and not make messes in the house. - RAH
Dana, I wish to start by thanking you for the direction. I would like to also mention, that I will try to ask most questions broken out down individually on later post.

I love your quote! LMAO!
 

protomate

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View attachment 11214

That's the ideal power from a rotor/prop. Taking into account total efficiency, it is usually closer to twice that (50% total efficiency).
5 feet diameter gives you 20 sqft rotor area, 8 feet gives you 50 sqft. With a thrust/weight of 400 lbs we're looking at respectively 40 and 25 kW. Figure in real-life losses and we're looking at 80 and 50 kW, or 105 vs 65 HP.

There's a reason helo's have large props/rotors:
View attachment 11215
Thank you very much Autoreply! I wondered if that equation was for a co-axial ducted fan arrangement?
 

protomate

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Thank you all again for your great help on this mission!
"Current project thought update, and it is current right or wrong!"
As does occasionally happen, I tend to spend 8-12hrs at a time performing research. This is where I am at (broken out into individual posts below):
 

protomate

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As I already have most of what I would need, I have decided to make an RC version to better understand the dynamics here. With what I am working with, it seems most economical to go with a 1/5th or 1/6th scale flyer. However, this prompts a whole new set of unknowns which must be satisfied (all based on a co-axial ducted fan arrangement with 2 or more motors at this time) I am actually thinking 4 engines may be optimal leaving the option to keep the yaw control throttle based, and provide enough power to hover with 3 engines, not climb, but hover:

1) I may be confused, but I think I remember reading somewhere a ratio of 1hp-5lbs of thrust or better might/should be the realistic target. Hence
Going with 270lb for pilot,fuel,laptop,airbag suit,gun(s),ammo,lunch etc (I am 6'1" around 220lbs currently, have close friends in the similar dimensions)
+ 370lbs for the machine per the original Pawnee VZ-1 if I remember correctly
Looking at 640lbs needed with engines wot for this estimation.
So, 640lbs/5lbs thrust hp = 128hp to maintain hover

1) My thought here is my intended machine design, and available materials will be reduced by quite a bit, but may require some redistribution of mass to maintain stability.
2) I am not going too crazy here, but at a glance it seems power to weight ratio with a little work or money for a 2 stroker can be 1lb to 1hp. I have been riding 2 stroke motors most of my life, modifying them, studying them. I understand the power to explosion formula quite well. Thought's on this in later posts
 

protomate

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RC Pawnee VZ-1 Test Unit ALPHA #1
As I know even skeptics may read this forum, that stay within their steel thinking box, I do not and will not. I firmly believe that partial-complete insanity is what drives innovation and mankind. Quick thought's:
How did we figure out what things are poisonous to eat?
Who was the first one to drowned?
How did we figure out how to build our current commercial aircraft?
Obvious answers to these ones huh? LOL

1)Test unit will be electric
How do I factor in the different torque vs hp curves between electric, 2 cycle, and 4 cycle power plants? Any historical data around to study?

2) Co-axial ducted fan calculations. Upon a quick look, it seems the single prop rc units might 1hp-2lbs thrust based on the size of around 90mm. Has anyone heard of larger ones with a little better lbs-thrust numbers? A quick calculation based on 1/5 on 1/6 scale based on 80hp from the original Hiller based on this puts my hp requirement for the model at:

1950's VZ-1 = 370lbs + 160lbs pilot = 530lbs so, 530/80= 6.625lb thrust per hp
1/5 scale 530lbs/5 = 106lbs/(crappy 2) = 53hp for off shelf ducted fans (I so hope this is not right!!!!)
1/6 scale = 83.3lbs / (crappy 2 factor) = 44hp

Please help! I am rather concerned about something RC with this mass flying around in my house. My rule of thumb for my RC heli's is no more than 200g, but this has a protected dicing unit

I have seen rc craft ducted/coanda that is single rotor. That may be fine for toys, but my experience with my heli's has been the co-axial can be set up to be impossible to crash into the earth. My single rotor collective pitch heli's need to fly at a scale height of around 300ft to even think about not crashing.
Single prop, no way!

-Any software around for calculation of co-axial ducted fan's lift, pitch, power, etc.?
-Single vs Co-axial, what is the thrust,pitch,spacing,power curves look like in comparison?
 
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protomate

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RC Pawnee VZ-1 Test Unit ALPHA #1 Design and Supplies

Airframe/fan shroud
I am looking for a realistic blade to wall tolerance figure. My thought is to build the model in a manner which can be scaled up. My understanding is that the wall to blade clearance is critical to optimized performance. Vibration also taken into account as this could cause the blades to contact the walls.

1) Anyone know of data containing tolerance and/or process lessons learned building a 5ft+ ducted fan?
2) Can anyone tell me why entrance and exit of the fan would not both be supported? First thought that comes to mind in a vertical fan is make the propeller drive deal with tension rather than compression.

ie: tappered bearing set at the exit, radial set up top. Might be able to design it lighter that way

Also would handle bouncing off tree's better when I am in the woods, narrow sidewalks, in shopping malls, inside schools, at a stop light congested with cars etc.
-Brings up another fantasy, imagine just jumping cars at stop lights!

foam machined CNC fiberglass/carbon covered structure?
Off the shelf fiberglass/carbon/plastic precision tubing and components bonded?

Need to source/look at full sized prototype and model scale things listed below to make informed decisions, any help sourcing at the very lowest (maybe even at the cost of safety/quality).

I am going my standard checklist:

-should it require a helmet? (if answer yes, will be a blast)
-STD's? If so which and how many we talkin?
-fireproof suit?
-bail money?
-electrical/mechanical/other risks

Then decide if redundant systems, higher safety factor, or throw the dice options are needed

-aerodynamic profiles like the ones that support a jet engine
-propellers, came across a IVO, seemed pretty nice. What are your thought's on used props?
 

Kristoffon

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This is very interesting and I wish you great success.

For it to be successful however I urge you to find a mechanical engineer willing to work with you as soon as you figure out ballparks for fan size and engine power. For those I'd start with the original Hiller (80 hp).

Then you can start exploring alternatives for the drivetrain. You'll need custom made adjustable pitch fans, a custom gearbox to drive them and if more than one engine is required, a way to join them. Multiple engines and propellers must be connected together or else if any deviates from the other by a tiny amount you'll start to yaw uncontrollably. Also the propeller's pitch will have to be matched precisely for that reason through trial and error.

By now you'll have enough data to make a weight estimate for the drivetrain and fuel and with payload all that's left is the airframe weight. If you started from the original Hiller the amount of weight left may be a lot in which case you can do with less power and recalculate drivetrain and fuel weights, or too little to make a strong frame in which case you start over with more horsepower.

Once you have the weight and power figured out correctly then you can start detailed design work on the gearbox, airframe, etc and hopefully start building soon.

Myself I'd go straight for a full sized prototype with possibility for remote control simply because doing a scale model will duplicate the design effort and I don't believe it's such an out of this world proposition that a well designed prototype won't fly.
 

Aviator2

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What's the latest?

It's been 2 years since the last post on this thread, so... Ben- how'd it work out?? Have you started building any equipment? I have been thinking about building this same kind of project (building a Hiller VZ-1 flying platform) and found this forum and I am very grateful to have found like-minded individuals sharing info on this very specific and unusual craft.

I particularly love the fact that this conference- and the people on it- are all about being helpful and understanding toward the newbies and homebuilders. And in that spirit, I will throw my first idea "out there" to see what anybody might think about its feasibility. This is it:

If you go to this website: http://www.sunflightcraft.com/en/index.php and click on Coax-P you'll see a contra-rotating propeller gear box with propellers attached to a Rotax 582 engine on an ultralight type aircraft.

So, here's the question: Let's say you take this engine, coax-drive and propeller combination off of that plane and tilt it so that the props are facing straight DOWN toward the ground (attached to an appropriate frame, ofcourse), and then wrap your basic fiberglass VZ-1 Hiller duct shroud around the propellers, and, voila- do you not have the essential engine-coax drive-propeller and fan-shroud portion of your project completed??!!

The 582 engine is 65 HP, the contra-rotating props add extra thrust, and as we all have read, the VZ-1 duct shroud adds 40% more thrust that didn't already exist. Would this be enough to lift the single occupant and airframe at least up to ground effect height?

I'm totally not touching on the other aspects of multiple engines, transmissions that combine engines, centrifugal clutches, or anything else- I'm only asking: would the Rotax 582 with Sunflight Craft co-ax drive and props lift a ducted Hiller VZ-1 off the ground?

 
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BBerson

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It might work. Just depends on the total weight. A duct can add thrust, but it also adds weight.

The 3.7 reduction ratio (designed for an airplane)is likely not optimal for static lift.
Do some tip speed calculations and find the maximum diameter.
 

Aviator2

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I remember thinking of that (the reduction drive not being a good thing in this case) before I started typing the post yesterday, but forgot to mention it before I finished the post.

The way I understand it, is this: if you have a powerful engine (without a reduction drive) driving the prop, then as you increase throttle power, and the blades speed up, and the wind from the propellers exits away from the prop- not so much directly behind the machine (as on a pusher-prop gyroplane, for example), but, less desirably, off to an angle, and more to the sides of the machine- resulting in less lift as the power, and RPM increases.

As the blade’s tips approach (and, conceivably, even pass) supersonic speed, the thrust eventually is exiting the propeller at, or close to, a 90 degree angle from the propeller- resulting in a critically reduced, or totally lost, amount of thrust from behind the machine.

However, in the case of a ducted fan, that is- a propeller enclosed within a shroud, as on the VZ-1 (see picture above), the “lost” thrust is contained within the shroud, and not allowed to escape laterally. Because of the direction of spin of the prop(s), all of the thrust produced by the propellers is vectored straight back, without loss of thrust due to comparatively high rotational speeds.

So, therefore- no reduction drive is necessary- the shroud saves and directs the thrust.

I realize this is a simplified explanation for why reduction drives are necessary in some cases, and not desirable in others.

And so, at this point I’d ask- FROM A LAYMAN'S PERSPECTIVE- is this a relatively clear and accurate explanation of the aerodynamics leading to the need for a reduction drive?
 
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Dana

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Not quite.

Propeller diameter and rpm are indeed limited by sonic speed. As the tips approach sonic speed, the local airflow over the blade can be more than Mach 1, and the resultant shock wave disrupts the airflow, resulting in loss of lift (thrust) and a huge drag increase. This is a completely separate issue from the tip losses (tip vortices) that any unducted propeller (and any conventional wingtip) has. It's not that the flow "spreads out" more the faster the tips are going.

The airflow behind a propeller does spread out somewhat, but not nearly to the extent you're describing. The advantage of a ducted fan is that the tip vortices can be minimized. Since you are controlling the tip losses, you can get away with having more tips (i.e. more blades). With more blades and the same input power, you can (have to) reduce the diameter, and since you're reducing the diameter, the tip speed decreases, so you can increase the rpm and still stay below sonic speed.

Dana

Shaw's principle: Build a machine that a fool can use, and only a fool will want to use it.
 
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