Recreating a 1/16th scale of Project Silverbug!

I'm thinking about trying to build a scaled down model of Project Silverbug out of Radio Control Aircraft parts.

For those unfamiliar with Project Silverbug, here is some background info.

www.cufon.org...

I'm guessing a Basic, scaled down radio controlled model of the silverbug will cost about 10 grand to produce what do you guys think?

Do you think this would be a good starting point in pursuing Flying Saucer technology?

Most interesting! Will you use a single ducted fan spun up by radial layout motors or a single motor for the fan? Controlling the flapper valves will be difficult and may require a bit of stability control software and a few potentiometers... what sort of motive force for the prototype IC, electric? What diameter platform were you considering? Will you use a PC and joystick wireless interface with ob video or a conventional R/C control set. Sounds neat and miight be able to be made to fit the budget providing enough "front end loading" (research) were done. Might be handy to have a CAD guy early on and a machinist. Getting ahold of the flight data of the original may or may not be of some value... for $10K USD corner cutting and smart planning would be the watch words. Learn from mistakes made by earlier attempts. Were you hoping for hover transitioned to flight? Lemme know how this works out, if you wish, please bounce stuff off me anytime, it does sound like a great project.

Thanx,

Victor K.

Thanks Kaminski, right now this plan is in its infancy so any help would be most appreciated. I was thinking of using several rc gas turbines(from rc planes) to propel the craft and was planning on using the basic rc setup to pilot the craft(remote instead of pc)

And I was most definately going to work on a hovering version before I attempted to build a more complete model for full flight.

I know a fabricator with a fair amount of Aircraft experience to help me cut custom parts.

Stabilizing/Controlling the craft with multiple flapper valves is the biggest problem I foresee.

The first part of this experiment I want to prove that we can get it to hoover under its own power. Once this part has been completed then I would plan on concentrating on the actuators(flappers) and controlling the craft.

What would you change Kaminski?

Will the turbines power the center fan via shaft or gear like the center fan on the JSF? That'll require some fancy machining of gears. A roller system? The silverbug drawings are a little complex but seem to indicate that the center fan had some sort over power connection to the radially arranged jet motors.

Perhaps do some mock up stuff on an umbilical till you get the lift strong enough and then work on stability... I'm thinkin' some sort of mercury switches or spirit bubbles instead of a gyro for stability indication fed to a bit of software to actuate and regulate the flappers.

Selecting bits and designing the center fan to accept force from your motors seems the first challenge. Maybe a separate motor for the center fan? The center fan will have to be fixed pitch unless an off the shelf variable unit could be found... hey maybe check out the skycar guy Paul Moller, maybe you can gain a little insight by looking at one of his motor pod deals which do produce a good amount of lift from a similar type of fan... see how he does his fans and see if some of his work could save a few hassles.

Victor K.

I was thinking that I might be able to get around the central fan if I used enough turbines. The central fan would just be the intake on my scaled down design. this would simplify the design drastically and would allow me to worry about the stability more.

What say you?

That sounds reasonable and wouild remove major hurdles. One other consideration would be torque cancellation... it"d be handy if half the motors spun in one direction and the other half reverse direction... the goal would be to reduce wobble and induced spin moment on the "bug". How big a diameter platform were you considering?

Victor K.

The diameter I would like to stay between is 3 to 5 feet. I would like to incorporate as many rc plane parts as possible to save me time from making the parts.

What size were you thinking we should shoot for?

The diameter would largely depend on the motor length, intake ring diameter and exhaust ring dimensions. Knowing the motor specs would be an asset (many bot component manufacturer's supply drawings and or digital CAD files).

The intake ring will need to breathe enough to feed all the beasts at 100% throttle without restriction so I'd guess the diameter at 2 or 3 times the motor intake effective swept fan area (converted to a diameter) to be safe.

I gave the exhaust some thought and as I recall turbines run rather hot out the pipe (I'm guessing depending on fuel 1500 - 1700 degrees F.) and the various pipes would need to lead into a "ring" manifold around the motors with vertical (downward) thrust apertures and correct me if I'm wrong horizontal thust apertures that would be configured to achieve forward motion in (hopefully LOL) the desired direction?

If this is the configuration, two troubles pop up, compressor stall owing to a lack of flywheel effect in the turbine type motors and overpressuring the exhasut side of the stall equation because of an exhaust too restrictive as apertures are reduced in size. Might be nothing but It'd be good to know what conditions can produce a stall on these babies and avoid those conditions. Picture your baby dropping like a stone from several feet - ouch!

The horizontal apertures seem easy enough, some sort of a set of sliding doors on the perimeter... the vertical thrusters are much more difficult. A photographic mechanical aperture style would be ideal but lotsa bucks. An alternate may be a spool valve like racing two stroke piston engines have to raise their exhaust port height (Yamaha YZ, TZ, RZ series come to mind) or a simpler conical plug that can be advanced or retracted from the downdward thrust stream perhaps on a jackscrew.

The exhaust seems the tough nut to crack... aluminum won't cut it (at least for very long) so Ti or stainless or iconel seem the best choices for the exhaust. In fact the exhaust will be the dominating feature of this beasty and you may wish to consider using it as a stressed member (hanging the motors and intake inside the exhaust ring) as a weight saving measure.

One other turbine thing... what's this one burn? And what is the specific fuel consumption at 100% throttle? What would be the duration of a successful "flight"? Fuel cells will need to be distributed evenly and away from all the hot bits... to avoid unbalancing the disk and fire. Oh yeah how do these motors get spun up? Pullcord? Spring and crank? Air?

One other thing you may wish to consider before turfing the idea of a central fan... how about a fan powered by a 10,000 or 15,000 RPM hard drive motor as an assist? Or two contrarotating? They spin some pretty fair mass of platters and are reliable and could help feed the dragons and provide a little lift. Batteries are heavy but the "Bug" may require balancing ballast anyway... just a thought.

Ah, almost forgot the thrust "leveller", I imagine a triangular layout of three mercury switches in a horizontal plane and using the switch input to activate the thrust corrective actions for horizontal stability. Perhaps some pre-existing R/C tech? Not having an onboard computer makes it tough. There may be a type of solid state switch that can do the same thing... I may just be unaware of them. The mercury switches will work (slower than digital) providing the fluid can be prevented from cavitating or fizzing from vibration.

Anyway I sent that file so enjoy!

Victor K.

[edit on 25-5-2006 by V Kaminski]

Sorry its taken me so long to get back to you Kaminski.

I've been chewin on the idea a bit and am thinking it might be best to go with a four turbine(cross shaped) of which ever cost efficient model that will provide adequate thrust to lift the saucer vertically and be sufficient to transition into forward flight. I might be in for a centralized fan in the central top part of the saucer. If it increases the thrust to weight ratio of the disk.

I must be honest and truly do not know much about model turbine engines and would appreciate any advice you might have on which type of fuel we should burn and which option would be best in starting the beast.

I would prefer to use a type of stainless steel if possible for the frame and skin if possible.

The way I see it. The most difficult part of reverse engineering something like will be in making it hover steadily for a duration of time.

Once we have this achieved then we will work on the transition into forward flight. I would like to use as FEW moving parts as possible for this transition so I was thinking of having an exhaust duct that opens and closes at each opposing 4 bottom-side "corners" of the disk. These will open for horizontal take off and close for forward flight.

At the same moment that the bottom-side exhaust ducts are closing exhaust ducts in the rear of the disk will open and proceed to transfer all thrust through the rear of the plane.

Not only will the exhaust system transition but so will the intake. The large centralized fan on top will close at which time front air intakes will open and force the exhaust out the rear of the craft.

This tranisiton will be similar to a JSF, however this disk will have several more turbines.

Unless the centralized fan can assist in forward speed I would prefer not use it.What say you?

Low Orbit, promiss to give us some pics when you start making it, and surely a video of it hovering when its ready!

Hi Low Orbit. 4 motors sounds good as starting point. Having four specific "points" for the thrust stream (as opposed to more) will mean exhaust design is that much more crucial to the balance of the platform. It may make it easier to fabricate. All the surfaces and structural bits that aren't in danger of "bursting into flames" you may wish to consider a lighter, cheaper and more easily worked material like sheet magnesium (source printing/lithography plates) or aluminum.

For the exhaust stainless sounds like the pragmatic answer although welding it (skillfully) requires skill and experience... when we used to need stainless bits fabbed-up for race bike pipes we'd go down to a restaurant supply house... their stainless counter top fabricator was the best SS welder. Good welding costs big bucks (or my favorite, favours)... have your fab guy sniff around.

Engine selection... there are several manufacturers. The one to choose? Uh, your decision not mine! Hey man, "I just work here." LOL. I'd suggest an airstart (if you have a compressor and/or a suitable air "pig" as it may save some weight compared to an electric start... but do some research... www.amtjets.com... (Advanced Micro Turbines Netherlands)... they have American dealers. I'm sure there are other choices, perhaps even made in America. See if they have stall data and design drawings... my bet is they do.

Oh yeah, ask them if they have "left" and "right" rotation motors... they may not, but I'd feel there was less of a chance of "the whole thing spinning" from lack of torque cancellation and harmonic couple induced "climb"... Uh, better explain: sit on a BMW motorcycle, rev the motor, you'll feel the bike try and "rotate" around the crank shaft and press against your right leg... it is this effect we may wish to cancel in the design stage as opposed to a potential workaround later. My fear is a slow rotation in the same direction as the turbines spin that could increase for a variety of reasons.

Fuel? Safest stuff would be Kero or Naptha... if you're bucks up I'd go for Jet Fuel Grade A1... set up the ECU and optimize it for whatever fuel you can get consistantly and have knowledge that the fuel is "fresh" to avoid the "gummy bears" that appear as fuel evaps and screws up fuel systems and pumps with scummies and particulate matter. Oh yeah, fuel consumption... an engine rated at 88 Newtons uses get this, 290 grams per minute! Larger motors: a pound and a half per motor per minute. Gonna need significant fuel capacity I think, and depending on layout quite likely a fuel pump(s) as there may not be sufficient room to get away with a gravity feed delivery.

A central fan "blow down" fan could buy you some lift and a tiny increase in intake pressure allowing more turbine thrust and a safety and stability factor not to mention this intake side pressure could help avoid compressor stalls from too closed an exhaust (smaller opening equals greater thrust pressure and back pressure) ... remember that at least some of the downward thrust will always be needed to maintain both altitude and through flappers, balance, until aerodynamic lift could be generated through "lift" caused by air moving over the disk. Disks (lenticular shaped ones) as a rule don't generate aero lift. You may wish to give this some thought. The central fan is entirely your call. If you feel you won't require it turf it. Adding one (or two one spinning each direction) after the fact may present challenges, perhaps expensive.

One of my friends suggested a system of tethers top and bottom to restrain the platform during R&D, this makes sense to me... some on top to prevent "uncontrolled" landing and some from the bottom to prevent the "bug" from getting too far away... give it two or three feet of vertical "slack" for the early-on flight enevelope.

Lotsa fun.. get back to me when you can Low Orbit and we'll jam on this some more... lotsa undecided stuff. An engine selection spec seems most critical, I'd start there.

Thanx,

Victor K.





[edit on 29-5-2006 by V Kaminski]

Here is a thread to a story I found about British Rail attempting to patent a flying saucer back in the 70's it might be worth a look even if it will probably not help us with any of the mechanical problems we will encounter in project silverbug.


To me this is mindblowing because British Rail is attempting to get patents for a Nuclear Powered Saucer in the Early 70's!!!

www.atsnn.com...

Take a look and let me know what you think.

One other thing comes to mind about the exhaust configuration, perhaps you could clarify for me, instead of a common and shared "Ring" 360 degree manifold exhaust pipe or "doughnut" with downward "nadir" ports and horizontal doors, you propose four separate exhaust ducts, producing four separate downward columns of thrust, right?

If so, the design then loses what the original Silverbug had called "Air-cushion" effect... check the drawings you provided and see what you think... the original's downward thrust seems to depend on sort of a perimeter curtain of downward thust to make use of this 360 degree vortex effect as an "extra" advantage, this may be critical... riding on 4 separate columns of thrust as opposed to more, or a continuous 360 degree "curtain" of thrust is going to require careful balance and caliburation and realtime control of those 4 separate exhaust streams. Maybe not.

Go see your fab guy, try this on for size, doodle out some stuff. Have a piece of thin wall stainless seamless tube of a diameter slighty greater than the diameter of one of your turbine exhaust pipes made into a ring or doughnut shape that would accept thrust from all 4 motors with flaps and valves added as your you and your fab guy see fit and what's easiest to actually make. You can design anything, making it is a far different proposition. Without knowledge of how, what goes nowhere, sort of hand-in-hand.

Materials, try Easton or American Steel, I used to get specialty metals from a place called Atlas Tool Steel... but that was the '70s, aside: did you know we had plasma coated aluminum brakes disks on our race bike at Daytona in 1977, a guy named Hunt used to make them, had 'em on my amateur class Ducati 900SS), AMA made them illegal... LOL.

Now let's say you do have a 4 way shared exhaust... we gain some benefits from not having four separate thrust values to deal with and compensate for... just one "tube pressure" value. Machine some flanges and spigots for the motors' exhuast to smoothly interface with this ring and hard mount the engines using the exhaust pipe ring as a "frame" to hang the other inboard components from.

If you were to choose a ring or doughnut exhaust design I can think of some flow bench software that knowing the turbine motors stall data we could use to tune the diameter and volume to "help" anti-stall capabilities... we should be able to generate "tube pressue" values from the software and pick the right "best guess" diameter tube before construction.

Also having a steel tube around the whole perimeter of the vehicle will help make the "bug", shall we say, "more sturdy". I think with a tubing guy and a machinist with a vertical mill that can cut stainless (not as easy as it sounds) all the various ports, doors and flaps are doable... the less parts the better. I've got a whack of ideas about thrust proportioning too... need an exhuaust and motor spec first.

There may too be other alternatives. Lemme know if you find an engine package that'll fit the budget eh?

Thanx,

Victor K.

[edit on 29-5-2006 by V Kaminski]

Check out the history of the AvroCar it save youself the trouble of the end results. It didn't work back then, it won't work now.