Design KI1603 X-WRAE
01-15-2017, 09:46 AM
#1
Design KI1603 X-WRAE
So I had this idea for a project that formed through thoughts and doodling as a result of '80s-era research by Sikorsky* to create a helicopter using an "X" wing that was able to change into a fixed wing aircraft and vice-versa. I sort of always considered making a fixed wing, .049 powered version for R/C. Not so interested in the heli format and it's associated complexities but wanted it to do more than just fly as a fixed-wing vehicle...
*Reference info: http://sikorskyarchives.com/X-WING.php
What I came up with was a means to fold the fuselage so that the center of gravity would be directly below the flying surface to allow for the transition into a vehicle capable of (hopefully) a soft, FF mode, auto-rotation - sort of like a maple seed. Used Fanfold foam left-overs to create a proof-of-concept glider that so far seems to show enough promise to hold my interest in pursuing it.
Hoping to use 6 channels (6 servos) to control roll, pitch, throttle (engine cut-off on demand), fuselage fold release, and flight control reconfiguration for auto-rotation sequence. (Now, as I write this, the statement alone is scaring me in reference to weight considerations...)
To be all balsa and ply construction with lots of design obstacles ahead but hoping to work through them as I go. Hoping this posting will be incentive enough to push forth.
Hence the name based on acronym: X-WRAE; X:(X) - W:(WING configuration) R:(RECOVERY by) A:(AUTO-ROTATION) E:(EXPERIMENTAL) to be pronounced - "X-Ray".
*Reference info: http://sikorskyarchives.com/X-WING.php
What I came up with was a means to fold the fuselage so that the center of gravity would be directly below the flying surface to allow for the transition into a vehicle capable of (hopefully) a soft, FF mode, auto-rotation - sort of like a maple seed. Used Fanfold foam left-overs to create a proof-of-concept glider that so far seems to show enough promise to hold my interest in pursuing it.
Hoping to use 6 channels (6 servos) to control roll, pitch, throttle (engine cut-off on demand), fuselage fold release, and flight control reconfiguration for auto-rotation sequence. (Now, as I write this, the statement alone is scaring me in reference to weight considerations...)
To be all balsa and ply construction with lots of design obstacles ahead but hoping to work through them as I go. Hoping this posting will be incentive enough to push forth.
Hence the name based on acronym: X-WRAE; X:(X) - W:(WING configuration) R:(RECOVERY by) A:(AUTO-ROTATION) E:(EXPERIMENTAL) to be pronounced - "X-Ray".
01-16-2017, 11:06 AM
#2
Hmm. Flight dynamics would probably be like a canard or tandem wing.
01-16-2017, 02:32 PM
#3
Don't know. Could think that I know just enough to get me into trouble. Was thinking more along the lines of a flying wing or disk - like those novelty airplanes (flying stop sign, Rountuit, flying lawnmower, etc.) Then, I thought about layout being similar in some ways to a conventional airplane - thinking way-forward swept wing here...
What I do know was that a simple duration and distance balsa glider I put together at a club organized building contest flew well enough for me to keep it over the years (I know you wouldn't want to use such a design that wasn't proven if you wanted to win such a competition but I just wanted to do something different from everyone else...). The pic shows it at half it's original length - it once had an aft stick fuse and "H" style tail I believe. After the aft fuse broke off, I removed some nose weight and found it flew almost as well (it will not track well if imparted with a yaw while launching). It does have dihedral that may account for stability which I won't be able to use in my target design. The B-24 Liberator inspired tail was added back to the tail end of the target design to provide yaw stability while maintaining durability.
For my glide tests, I have found that the CG is located just forward of the intersection of the "X" planform on both the balsa and FFF glider.
I'm guessing from a design standpoint that a general rule of thumb is to provide controllability where there is the most mechanical advantage. Based on some quick "hack glide tests" using masking tape pieces as control surfaces, I'm thinking pitch control on aft two legs and roll control on fwd two legs of the X-wing planform. May not work but that's what I'm thinking.
What I do know was that a simple duration and distance balsa glider I put together at a club organized building contest flew well enough for me to keep it over the years (I know you wouldn't want to use such a design that wasn't proven if you wanted to win such a competition but I just wanted to do something different from everyone else...). The pic shows it at half it's original length - it once had an aft stick fuse and "H" style tail I believe. After the aft fuse broke off, I removed some nose weight and found it flew almost as well (it will not track well if imparted with a yaw while launching). It does have dihedral that may account for stability which I won't be able to use in my target design. The B-24 Liberator inspired tail was added back to the tail end of the target design to provide yaw stability while maintaining durability.
For my glide tests, I have found that the CG is located just forward of the intersection of the "X" planform on both the balsa and FFF glider.
I'm guessing from a design standpoint that a general rule of thumb is to provide controllability where there is the most mechanical advantage. Based on some quick "hack glide tests" using masking tape pieces as control surfaces, I'm thinking pitch control on aft two legs and roll control on fwd two legs of the X-wing planform. May not work but that's what I'm thinking.
01-17-2017, 08:30 AM
#4
The control layout you describe ought to work. One way to look at it is that you are rearranging a rhomboid wing, a design that has been done a number of times. The forward wings will need to be fairly rigid to keep them from flexing during pitch changes but this is generally simpler with smaller models. A carbon fiber tube would be both light and rigid. The only thing I'm not clear on is how to initiate the rotation. Once you get it rotating you basically have a gyrocopter rotor. Does the foam model initiate auto rotation? It rather reminds me of those paper helicopters that we made in grade school.
01-17-2017, 06:16 PM
#5
Considering several options: conventional control surfaces with two on the (dare I say it) leading edge (one might say - "let me know how that works fer ya"), full flying surfaces pivoting with tube in socket, something along the KISS principle of paper helicopter you mentioned - with displaced surfaces to initiate the rotation or maybe even something I haven't considered yet...
Last edited by H5606; 01-17-2017 at 06:19 PM. Reason: Redundancy
01-19-2017, 08:26 AM
#6
Why not go with a full pivoting surface ( kind of like a helicopter rotor blade)?
01-20-2017, 07:12 AM
#7
In playing with several sizes of carbon tubes: a 1/2" OD seems like it would entail too fat an airfoil to accommodate it and an even larger sleeve - a 5/16" OD tube would lend nice thin airfoil but seems a little too flexible - and a 3/8" OD tube looks to be the best compromise.
Also wondering about integrating FF helicopter technology - I once had a Cox Sky Copter (looked like a mini Bell 47 with four bladed rotor head powered by an .020) - it used blades that were offset weighted at the tips to - I'm guessing - to position the blades at the proper pitch angle for the ascent phase as well as the descent phase. Wish I still had it now to study.
In this case, for the target design, thinking pinned blades for controlled flight mode that would pivot to a "descent pitch" by means of an offset weight when unpinned. Still would have to add separate means for pitch and roll controllability which introduces back the complexity variable.
02-09-2017, 05:36 PM
#8
After mulling this subject over, selected the 3/8" carbon tube for a full-flying controllable surface. First order of business was to try to make a sleeve:
Spiral wrapped the 3/8" carbon tube with a 2" wide strip of clear Monokote and buffed it with some carnauba based car wax I found in the garage.
Cut 2" wide 6 oz glass cloth, wet cloth out on some scrap paper with a credit card squeegee, spiral wrapped tube with a single layer (like a drinking straw or cardboard tube). It released fine but I wasn't happy with the flexing so I applied red brand Scotch tape lengthwise (probably a mistake) to the carbon tube, waxed it and slid the sleeve back on again - added another layer of glass cloth, wrapped it with some peel ply and another piece of clear Monokote this time - used a heat gun to shrink the exterior Monokote cinching it all against the tube. Long story short - I could see that some resin made it's way to the inside surface during application of second layer - I knew at this point it probably would be a problem and it was...
Pulling the sleeve off was a SOB but some coaxing with repeated heating and cooling, tapping, unintentionally fracturing the end of the carbon tube (only a couple inches luckily), cursing, praying, and blisters from twisting and pulling over a span of two days, I now have a useable sleeve. I think it will be long enough to cut into four individual pieces for each blade/wing panel.
Spiral wrapped the 3/8" carbon tube with a 2" wide strip of clear Monokote and buffed it with some carnauba based car wax I found in the garage.
Cut 2" wide 6 oz glass cloth, wet cloth out on some scrap paper with a credit card squeegee, spiral wrapped tube with a single layer (like a drinking straw or cardboard tube). It released fine but I wasn't happy with the flexing so I applied red brand Scotch tape lengthwise (probably a mistake) to the carbon tube, waxed it and slid the sleeve back on again - added another layer of glass cloth, wrapped it with some peel ply and another piece of clear Monokote this time - used a heat gun to shrink the exterior Monokote cinching it all against the tube. Long story short - I could see that some resin made it's way to the inside surface during application of second layer - I knew at this point it probably would be a problem and it was...
Pulling the sleeve off was a SOB but some coaxing with repeated heating and cooling, tapping, unintentionally fracturing the end of the carbon tube (only a couple inches luckily), cursing, praying, and blisters from twisting and pulling over a span of two days, I now have a useable sleeve. I think it will be long enough to cut into four individual pieces for each blade/wing panel.
Last edited by H5606; 07-04-2017 at 04:36 PM. Reason: added missing info; put pics back in order
02-11-2017, 03:35 PM
#9
Regarding the first picture: cut out a displaced/offset rotor blade/flying surface as seen on the left; the existing example is on the right (each blade on it has twist set like a propeller as mentioned earlier). When dropped from chest height, the new displaced rotor blade was expected to rotate, but it fell like a pancake without rotating. The other rotor blade (on the right) makes one full rotation before touching the floor when dropped from chest height.
If this idea had worked, was thinking I could eliminate the - forward flying - relative "asymmetrical" forces by orienting (clocking) the rotor head through trial and error to trim for best fwd flight or perhaps it wouldn't have even been an issue...
The second picture Is the paper helicopter that works quite well as expected.
Last edited by H5606; 02-11-2017 at 04:05 PM. Reason: added info
02-26-2017, 03:43 PM
#10
At some point its time to shoot the engineer and move forward...
Drew up plans for the control distribution center section and a wing panel that will be typical for all four.
Cut carbon tube - one >12" length and two >6" lengths - fish-mouthed short ones to butt with long one just FWIW; plan to support center with a 1"x1" end-grain balsa block. Pic shows surface gauge marking length of the 4" 'glass sleeves that'll glue into each panel.
Drew up airfoil finally settled on: will be double D-tube semi-symmetrical with flat bottom (to facilitate construction) and Phillips entry (thinking that's what its called?) at each end with 1/8" spars, 1/16" sheeting and cap strips, - ends up fatter than I wanted but oh well.
Thinking of needing some fixture to ensure alignment during construction of center section.
Drew up plans for the control distribution center section and a wing panel that will be typical for all four.
Cut carbon tube - one >12" length and two >6" lengths - fish-mouthed short ones to butt with long one just FWIW; plan to support center with a 1"x1" end-grain balsa block. Pic shows surface gauge marking length of the 4" 'glass sleeves that'll glue into each panel.
Drew up airfoil finally settled on: will be double D-tube semi-symmetrical with flat bottom (to facilitate construction) and Phillips entry (thinking that's what its called?) at each end with 1/8" spars, 1/16" sheeting and cap strips, - ends up fatter than I wanted but oh well.
Thinking of needing some fixture to ensure alignment during construction of center section.
Last edited by H5606; 02-26-2017 at 04:24 PM.
03-04-2017, 07:16 PM
#11
Used some 1/16" x 3"W C-grain in the stash to make 6"W material in order to have it wide enough to cut a center section base plate. Set up miter gauge to sand in 45* bevels on the walls and fabricated a 4" x 4" x 1" box.
Fabricated 1/16" ply master rib patterns. Using a single 1/16" x 4"W hard balsa sheet with three horizontal cuts and 8 vertical cuts yields 36 rib blanks. Stacked half what was needed for two wing panels - 22 between ply rib patterns, staked with some 1/8" bamboo dowel pins and a tiny amount of CA to tack fore/aft edges before drilling for pins.
Sanded the stack but forgot to drill center hole on first set; used 5/16" brad-point drill and rat-tail file to open up center hole and it worked out well.
Fabricated 1/16" ply master rib patterns. Using a single 1/16" x 4"W hard balsa sheet with three horizontal cuts and 8 vertical cuts yields 36 rib blanks. Stacked half what was needed for two wing panels - 22 between ply rib patterns, staked with some 1/8" bamboo dowel pins and a tiny amount of CA to tack fore/aft edges before drilling for pins.
Sanded the stack but forgot to drill center hole on first set; used 5/16" brad-point drill and rat-tail file to open up center hole and it worked out well.
03-15-2017, 02:33 PM
#12
Finished up spar notches to complete all ribs for 10 ribs per panel.
Used scrap length of carbon tubing to try to create tooling - a long hole saw - brass tubing would have been better but didn't have any handy.
Used surface gauge to mark up the center section box walls for hole locations.
Fabricated 1" end-grain balsa retention block faced with cross-grain pieces, located with spacer blocks and bonded to floor of control distribution center section box.
Fabricated a fixture using some scrap MDF for a base to try to drill the center section box for the four spar tube/pivot locations. Corner blocks locates the center section and holds it firmly for drilling process. The carbon tube had to have teeth filed in after each hole attempt and used a brad point to finish job on each wall. During the drilling process the cutting end would get hot and burn away the resin leaving fuzzy carbon strands. Suspect sharpened or toothed brass tube should have worked much better...
Final pic shows center section with one full length tube running through with the two short ones butting at the center.
Used scrap length of carbon tubing to try to create tooling - a long hole saw - brass tubing would have been better but didn't have any handy.
Used surface gauge to mark up the center section box walls for hole locations.
Fabricated 1" end-grain balsa retention block faced with cross-grain pieces, located with spacer blocks and bonded to floor of control distribution center section box.
Fabricated a fixture using some scrap MDF for a base to try to drill the center section box for the four spar tube/pivot locations. Corner blocks locates the center section and holds it firmly for drilling process. The carbon tube had to have teeth filed in after each hole attempt and used a brad point to finish job on each wall. During the drilling process the cutting end would get hot and burn away the resin leaving fuzzy carbon strands. Suspect sharpened or toothed brass tube should have worked much better...
Final pic shows center section with one full length tube running through with the two short ones butting at the center.
03-18-2017, 04:13 PM
#13
Framed up first of four wing panels.
A little head scratching over control means - sketches circled in red show what I thought would have been pretty cool - servo output shaft direct drive but, ultimately, decided to go with conventional pushrod linkages to a control horn.
Drew up control horns based on a 1/4" travel at the servo output arm. Small circle represents servo travel arc for inner most hole; large circle represents flying control surface arc - radius determined by 1/4" travel for 5 degrees of travel up and down. Figured tangent line between the two circles should provide symmetry for equal movement in both directions hence the reason for the "leaning" control horn design. Since this is a full flying surface design, have some concern over having too much control throw now even at 5 degrees and can't decrease it at present control horn length (I can go in [increasing throw] but I can't go out) unless I add an extension. Keep trying to justify the decision in that aircraft design is a compromise of components and probably need more throw for the auto-rotation mode anyway...
Xerox copied my drawing, cut out the horn sketch and 3M77'd it to a stack of four .035" G-10 blanks. Drilled holes, pinned, cut, and sanded to shape for four identical control horns. Horn size ends up being about 1 3/8" center to center.
A little head scratching over control means - sketches circled in red show what I thought would have been pretty cool - servo output shaft direct drive but, ultimately, decided to go with conventional pushrod linkages to a control horn.
Drew up control horns based on a 1/4" travel at the servo output arm. Small circle represents servo travel arc for inner most hole; large circle represents flying control surface arc - radius determined by 1/4" travel for 5 degrees of travel up and down. Figured tangent line between the two circles should provide symmetry for equal movement in both directions hence the reason for the "leaning" control horn design. Since this is a full flying surface design, have some concern over having too much control throw now even at 5 degrees and can't decrease it at present control horn length (I can go in [increasing throw] but I can't go out) unless I add an extension. Keep trying to justify the decision in that aircraft design is a compromise of components and probably need more throw for the auto-rotation mode anyway...
Xerox copied my drawing, cut out the horn sketch and 3M77'd it to a stack of four .035" G-10 blanks. Drilled holes, pinned, cut, and sanded to shape for four identical control horns. Horn size ends up being about 1 3/8" center to center.
03-24-2017, 05:45 PM
#14
Backyard video documentation here to try to substantiate claims that got this whole thing started.
Includes multiple forward flight launches and a demo of the folding and auto-rotation mode.
Tried in vein, but I have no idea how to upload videos with a still to click on... Ticks me off.
Anyway, link is here: https://youtu.be/UoFVSbsnSIY
Includes multiple forward flight launches and a demo of the folding and auto-rotation mode.
Tried in vein, but I have no idea how to upload videos with a still to click on... Ticks me off.
Anyway, link is here: https://youtu.be/UoFVSbsnSIY
03-31-2017, 03:12 PM
#18
Geez, the tall guy gets all bent out of shape over the littlest of things coming up...
Dig all the photographer's turning attention away from VIP on stage to more interesting subject (VBP) overhead.
Also comment below vid: "He's going to need a new main shaft."
Dig all the photographer's turning attention away from VIP on stage to more interesting subject (VBP) overhead.
Also comment below vid: "He's going to need a new main shaft."
Last edited by H5606; 04-01-2017 at 07:12 AM.
04-12-2017, 05:39 PM
#20
Gasparov - is this the chess champion or someone with the same name?
With just a few descriptive additions, a new name is created - Visually Astounding, Repulsively Interpreted, X-Wing Recovery (by) Autorotation Transforming Experimental Demonstrator - and results in the acronym: VARI X-WRATED
.
Pics of engine choices with accessories plus full-size profile of fuselage assy and product engine taken w/ smartphone and painfully loaded to pc...
Don't fully understand the addition of the choke tube to the backplate of the Surestart.
With just a few descriptive additions, a new name is created - Visually Astounding, Repulsively Interpreted, X-Wing Recovery (by) Autorotation Transforming Experimental Demonstrator - and results in the acronym: VARI X-WRATED
.Pics of engine choices with accessories plus full-size profile of fuselage assy and product engine taken w/ smartphone and painfully loaded to pc...
Don't fully understand the addition of the choke tube to the backplate of the Surestart.
Last edited by H5606; 07-23-2017 at 07:15 AM.
04-20-2017, 04:30 PM
#21
Checking verticality of ribs prior to bonding structure with a HOB tool; fourth panel framed up prior to pulling away from wing jig and happy with results so far except seeming heftiness of center section.
Pic of single panel mated to center section and then of all four added to same - kind of reminiscent of solar array on top of NASA's long gone Skylab.
Continuing to work on fuselage drawing - hashing out hatch access for tank and throttle servo - also intermediate former locations to do yet...
Pic of single panel mated to center section and then of all four added to same - kind of reminiscent of solar array on top of NASA's long gone Skylab.
Continuing to work on fuselage drawing - hashing out hatch access for tank and throttle servo - also intermediate former locations to do yet...
04-30-2017, 04:30 PM
#23
Added details to fuselage side view including a - tentatively planned for - removable nose section (throttle servo, tank, and engine positions shown), traced fwd fuse, aft fuse, and vertical stab to tracing paper, 3M77'd to paired 3/32" balsa sheeting tacked together with double face tape. roughed out cuts on band saw prior to detail hand sanding of stacked parts. Giant (mid-Atlantic grocery store) brand masking tape that I was at first dissatisfied with actually came in handy for the task of tracing as it is very low tack and can be pulled off without lifting underlying paper it is attached to...
05-07-2017, 04:49 PM
#24
Fabricated 3/32" ply doughnuts for bearing hard-points to all pivot points on fuselage - drilled with Brad-point bit, cut squares, 3M77'd together, installed on dowel pin in scrap drill press back-plate, knocked off corners with band-saw then clamped to sanding table and used belt sander sort of like lathe to sand round.
Fabricated hinge knuckle fuselage interface sides.
Used 7/8" Forstner bit to open up the three, paired fuse side parts for hard point installation. Enlarged holes with hand sanding tool for close tolerance fit. Pulled off tracing paper without too much difficulty - lacquer thinner seems to help the few points of stubborn 3M77 to let go...
Sanded perimeters and all parts flush at hard points; happy to see that all parts have nice tight fit against proposed pivot post. Glued vertical stab to aft fuse and added cross-grain perimeter parts - plug for aliphatic white glue included that sands so very nicely, then added pattern, and sanded vertical stabs on aft fuse to shape.
Planned three week hiatus from build.
Fabricated hinge knuckle fuselage interface sides.
Used 7/8" Forstner bit to open up the three, paired fuse side parts for hard point installation. Enlarged holes with hand sanding tool for close tolerance fit. Pulled off tracing paper without too much difficulty - lacquer thinner seems to help the few points of stubborn 3M77 to let go...
Sanded perimeters and all parts flush at hard points; happy to see that all parts have nice tight fit against proposed pivot post. Glued vertical stab to aft fuse and added cross-grain perimeter parts - plug for aliphatic white glue included that sands so very nicely, then added pattern, and sanded vertical stabs on aft fuse to shape.
Planned three week hiatus from build.
05-29-2017, 01:54 PM
#25
Was having trouble picking up where left off...
To help visualize things, thought it beneficial to draw a top-view. While drawing, it helps to give me that warm-fuzzy for planning ahead. Incorporated 1/64th" clearances between the hinged areas and hoping it will provide ample wiggle room to fold up friction-free. It looks a little wide right now, but cross section of the folded fuse will be completely square ("round?") and an O.S. 10 FSR looks like it will fit if the Cox .049 doesn't have the oomph to pull it.
Also thinking about using those strong, rare-earth magnets but wondering if gravity will be adequate to bring the nose and tail together to nest completely and stay together during the descent phase.
To help visualize things, thought it beneficial to draw a top-view. While drawing, it helps to give me that warm-fuzzy for planning ahead. Incorporated 1/64th" clearances between the hinged areas and hoping it will provide ample wiggle room to fold up friction-free. It looks a little wide right now, but cross section of the folded fuse will be completely square ("round?") and an O.S. 10 FSR looks like it will fit if the Cox .049 doesn't have the oomph to pull it.
Also thinking about using those strong, rare-earth magnets but wondering if gravity will be adequate to bring the nose and tail together to nest completely and stay together during the descent phase.
Last edited by H5606; 05-29-2017 at 02:09 PM. Reason: Something jogged my memory...