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Topics - Deerslayer

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31
Plans, Projects, Building and Flying Tips / Hinging of Foamboard
« on: July 23, 2017, 08:45:23 AM »
If you don't check in to the Flitetest site from time to time, you are missing some neat stuff. Somewhere in there, I saw the following idea and tried it out on some scrap. It is simple and easy and really works well! I doubt that one would ever break such a hinge, as it has the 2 paper layers sandwiching the minute foam layer at the joint line, yet it is as flexible as a taped or glue film hinge, in my opinion. (Perhaps we should add this into the Flypaper College Of Aero-Nut-ical Knowledge textbook?) Remember, there is more than one way to skin a cat - not that I am into that kind of thing.

https://www.flitetest.com/articles/ironed-foamboard-hinges


I wonder - should we be having the occasional seminar out at the Toyground, during our winter playdays, on some of this Foamology? Of course, it would be  FCAK certified!

32
Here is a little video I cobbled together for your amusement.

My overall objective was to create a VTOL Tailsitter which would use only the DX9's incredible programmability and a Lemon Stab+ receiver, cheap HK servos and a couple of sheets of Elmers foamboard. Stabilization and self-levelling were available, and although I tested each briefly, neither was otherwise employed.

I got a lot of flight experience and several more ideas from this flight. My Mk.1 version also flew without incident; however, I was not satisfied with a couple of aspects of its design and handling, so along came Mk.2.

In another, yet to come, video, I have some background on the project and demonstrate some of the technical aspects.

So, here it is:

https://youtu.be/FsS9Zsh-NR8

33
Plans, Projects, Building and Flying Tips / Fun Cub Gear Mount
« on: July 12, 2017, 08:32:17 AM »
Cliff designed a really nice mount system to replace the notoriously weak plastic one. Two drawings and a picture are attached. Do not be scared off by the detail and dimensioning. Just print out the drawing, stick it onto some suitable material and start cutting. Of course, someone who has a laser or other cnc  system could whack out a slew of these things and create a major product line, becoming very wealthy!  8)

Thanks, Cliff!

34
 I have been following this development for quite awhile.The Perlan project home is at http://www.perlanproject.org/

 Back in my soaring days, I longed to do wave soaring. Once, at Sugarbush VT, I was able to ride the wave, but not to a very high altitude. It was pretty exciting, nevertheless. The tow was quite demanding and violent, as we climbed through the rotor (that is where many aircraft have been taken down in mountainous regions when a wave is working and they encountered the rotor). I was a very inexperienced pilot, only a handful of flights past solo and it was a bit sweaty!

 Then, as we entered the wave, I released from the towplane and everything got quiet and smooth; he dove back down through the mess to pick up the next flight. No sensation of climbing, apart from the variometer showing about 2000 ft/min, as I flew pointed upwind. The winds aloft were in the 50 mph neighbourhood, so you could set up at that sort of airspeed and have 0 groundspeed. You just sit there and ride the wave, watching the vario and keeping track of where your landing area is.

  My flight was cut shot when cloud started to develop below me and I had to find a hole to let down through. Altogether, a flight that I remember in great detail some 45 years later. In those days, Paul Bickle held the world altitude record of 46,000 ft., in the mountain wave at Bishop CA. That record stood of decades.

 So much for all of that! Now, on to the real flying.

The following is an article from Aviation Week:


Airbus
The Perlan 2 stratospheric glider has arrived in Argentina as the Airbus Perlan Mission II team bids to set a new altitude record for sailplanes.
The pressurized Perlan 2 is designed to reach 90,000 ft., but chief pilot Jim Payne is hoping to reach 60,000-65,000 ft. this year, enough to beat the record of 50,727 ft. set by Perlan 1 in 2006.

Perlan 2 arrived by ship in Mendoza, Argentina, and on July 2 will begin the 2,600-km (1,600-mi.) road trip to El Calafate in Patagonia. From there the glider will be launched to ride standing mountain waves—air currents formed by the Andes—to successively higher altitudes.

The two-seat aircraft is designed to use mountain waves that reach into the stratosphere to achieve wing-supported flight at higher altitude than any previous aircraft, unpowered or powered. This becomes possible when mountain waves interact with the polar vortex.

Perlan 2 made its first flights from El Calafate in 2016, but was late arriving in Argentina and missed most of the winter season—one in which the polar night jet was weaker than usual. Since returning to the U.S., the aircraft has exceeded 30,000 ft. in flights from Minden, Nevada.

As the glider is expanding its flight envelope as it flies, altitude will be increased in increments of 5,000 ft. At each new altitude, a flutter test will be conducted using exciters built into the wing. If the results match the aeroelastic modeling, Perlan 2 can proceed to the next altitude.

Payne dose not expect to reach 90,000 ft. during this season. “The conditions are only right for a few days a year, and some years not at all,” he says. Ahead of this year’s flying campaign, wind speeds have been increasing in the stratosphere—a promising sign, he says.

Mountain waves would normally not extend above the tropopause, but in winter near the poles they can join with the polar night jet so that wind speeds keep increasing through the tropopause and into the stratosphere. As long as wind speed is increasing, Perlan 2 can keep climbing, Payne says.

Perlan 2 is similar in design to an Open Class competition sailplane, but with a larger wing area and an airfoil optimized for high altitude. It is unique in being pressurized. Perlan 1 was not, but it was hard for pilots to control the glider once their pressure suits had inflated and stiffened.

Pressurization required careful design to prevent leaks, but has been successful, Payne says. Nonetheless, a 115 ft³ scuba tank is carried to replace any air that does escape. Air and battery supplies are sized for an 8-hr. mission. The nominal mission is a 1-hr. tow to the waves, 3-hr. climb and 1-hr. descent.

Perlan 2 has been modified and upgraded since the 2016 flights from El Calafate. This includes adding heating for some systems because of the very low temperatures at altitude. Also the glider can now be flown unpressurized at lower altitudes to prevent the buildup of condensation early in the flight.

The glider is flown at its minimum sink-rate speed of 40 kt indicated airspeed (IAS) and climb/descent rates as high a 2,500 ft./min. have been seen in mountain waves. The allowable speed range at high altitude is 38-54 kt IAS—the latter equating to Mach 0.62 at 90,000 ft. because of the low air density.

In case the crew needs to descend rapidly in an emergency there is a drogue chute in the tail that will bring the glider down at 80 kt IAS. There is also a ballistic recovery parachute to bring the fuselage and crew down safely if the wings break off. This is safer that trying to bail out, Payne says.

Airbus is sponsoring the Perlan 2 mission and providing engineering expertise. One reason is the opportunity to explore the upper atmosphere. “With time, aircraft will have to fly higher” as air traffic grows, says Ken McKenzie, senior vice president of strategy and development of Airbus in the U.S.

35
General Discussion / Amazing 3D video at Huckin' In The Valley
« on: May 29, 2017, 08:02:03 AM »
There is more stuff over in RCCANUCKS but this is the one that really got me! Oscar quality  8)
https://youtu.be/OrePaMm2XpA

40
The following is being offered in the hope that other builders of foamboard flying objects can utilize one or more of the described techniques.

I am completing #7 or #8, not sure which (I have a good memory but it is rather short), in my series of foamboard-based deltas. Some have been pushers, a couple are tractors (one converted from being a pusher, the latest being created as a tractor). I have experimented with vertical vectored thrust, vertical + horizontal vectored thrust, etc. A couple of the earlier pushers carried a Mobius, most recently with the 5.8GHz Tx, to do some FPV.

 Whenever I get bored, an uncontrollable itch to hack out something shows up.

 The FPV version worked so well (Wilf flew it and even landed it FPV, so you know it is a magical design!), that I decided to make one primarily for that purpose.

My design criteria, particularly with this plane, is to make things from foamboard that:
a) fly well (stabilizer assisted)
b) are as cheap as possible (not allowed more than 3 foamboards, no exotics such as carbon fibre, i.e., a $5 aircraft structure)
c) doesn't look like it fell off the $Tree truck
d) applies everything I have learned so far (if my incredible memory holds true)

This particular delta is constructed from the Elmers foamboard (sold by Dollarama), rather than the Adams product (sold by $Tree). While this will be slightly heavier than some of my previous ones, it has terrific structural strength without the need for any CF, etc. The paper covering, which is very well bonded to the base foam on the Elmers product, gives high strength and adheres very well, following the particular treatment that I use for strength and for water-proofing. Of course, the weakness with any foamboard is in compression, as it will buckle easily. Hence the choice of a KFM type of airfoil, i.e. multiple (3 in this case) layers at the leading edge, reducing to 2 at perhaps 40% chord and then to single layer a bit further back. There may be some aerodynamic advantages to this airfoil, too, but the jury is still out on that one.

Here is the basic technique. Note: some of the first 3 steps are rather specific to my specific design):

1. I mark and cut the various parts from the foamboard. This includes the 3 wing section layers and the 2 vertical fin layers. In this latest model, I have a multiple layer slab fuselage (3 layers at the front, reducing to double layers aft of the "cockpit"). The wider front fuselage has a real purpose; it allows me to set in a solid, wide base upon which to set the FPV camera/transmitter and at the optimum angle (roughly 10 degrees below horizontal, to start with. If subsequent adjustment is required, the knife and hot glue gun will take care of that nicely!

2. As I intend to create rounded leading edges and need to be able to sand easily, I lightly score just through the paper back perhaps 1 cm from the leading edge on the sides which will be joined together, only. I do this freehand, with a sharp Exacto or cutoff knife or razor blade. This will also be done on the outside leading edges at a later stage of construction.
 After scoring, pick at one edge and gradually peel off the paper strip. The key here is to ensure that you have cut completely through the paper. I find that holding the paper rather flat to the board and slowly pulling at a slight angle toward the front works well. Whatever works for you! If you have a little bit of paper residue here and there, don't worry, it will not prevent gluing and won't be visible anyway

3. To make it easier to more precisely mate the wing surfaces, I pre-fit them and use about 3 round toothpicks down the center line to be my temporary alignment dowels. Poke then through, then remove them until after the contact cement is applied to the surfaces,
Spray the surfaces to be joined with contact cement. I use 3M Super 77 these days, as it is quick and simple. I would likely use brushed on water-based contact cement if I were building a foamy with the paper stripped. Do not overdo it, just a nice even coating, and do not get too close or heavy on the areas you have stripped. Then, after a few seconds, give another light coating near the edges of the joining surfaces; the initial coating will protect the foam from being eaten away.

Do not be alarmed that your foamboard may have bowed somewhat. If you do a good job on mating the sections and then weight them down for a couple of minutes, they should end up perfectly flat.

 Stick your locating dowels (toothpicks) into one of the surfaces.

 Within perhaps a minute of spraying, mate the surfaces. You only get one chance with contact cement, hence the locating dowels!

 Now, back to completely design-independent aspects! Treating all surfaces as follows will greatly strengthen the structure and make it water-proof. As well, you can potentially tart up your $5 aircraft so that it can stand proud out there in full view of the Peanut Gallery. (No one really cares, but, flatter yourself anyway.)

4) I use Minwax Polycrylic Finish Protector, bought at Home Depot in a 1 litre can, to protect/strengthen/finish a surface . This is a water-based clear polyurethane product. I dilute a small amount of it with water in, say, 1:5 ratio and keep it in a small bottle.

 There are a couple of other items which are part of my processing, all of which are water-soluble and compatible with each other. Light spacking compound can be used either by itself or mixed with your water-based craft paint to fill or repair gouges, etc. The edges of the paper covering can be well sealed to the foam, by using just the polycrylic or, as I now prefer, by painting the edge area with Mod Podge (I had some lying around for a decade or more and finally found a good use for it. there are other things you could use, too.

I brush on one or two coats of the thinned polycrylic. This stuff dries in minutes, no need to sand between coats. As with any of these products that I use, you can come back a day or a week later and apply more stuff, it will adhere to the previous application. Nice feature!



 5) Now that you have sealed and strengthened the whole structure, it is time to shape the leading edge, etc. as was done before joining flat sections, I now freehand cut the paper, back perhaps 1 cm from the leading edge and peel off the strip. You will find that it goes much easier now, as the polycrylic treatment has  greatly improved the paper' strength.

 After rough shaping of the leading edge, if you notice that there is some separation of layers, now is the time to fix it. I brush on Mod Podge or whatever and work it into the joint, wiping off excess. Weight the leading edge down (no need to be too aggressive) and leave it alone for an hour or so. If there is still any separation, you can deal with that later with filler and/or paint.

6) You can now carefully sand the leading edge. I use 150 sandpaper, Sand right up onto the paper, if you wish - just try to mostly sand in the direction away from the paper and/or parallel to its edge. You will still have a detectable little ridge at the paper. What to do? Option 1 - don't worry, no one else cares, it won't affect the flight characteristics and you can inform the Peanut Gallery that this is a boundary layer trip strip. (They may not know what you are talking about, but they might even think that you know something about aerodynamics, Just try to keep a straight face. Besides, it may actually be true!). Option 2 - get serious and really clean it up, per the next step, so that the joint will be practically invisible.

 With the shaping of the leading edge, etc., complete, let's treat and finish that area. I use thinned spackling compound brushed or scraped on, optionally mixed with whatever paint I may plan to use, and smear it on. Let it dry for several hours, then sand to shape. Repeat as you see fit.

 When I really think I have wasted enough time and effort and beers on this shaping effort, it is time to do the finishing.

7) Apply a couple of coats of polycrilic to the leading edge area, at least past the paper joint and perhaps over the rest of the structure. It will be an insignificant weight, as it is probably 90% water, which evaporates.

8) It's paint time! I use the craft paint (little bottles, from Michaels, Walmart, etc.) and either a small foam brush or decent sized artist's brush. It is cheap and you use surprisingly little. This has previously been thinned down with water, and I keep a small container of water handy to dip my brush into, as needed. I put a puddle of paint on a plastic credit card, dip the brush into that as needed, perhaps dip the brush into water occasionally to thin down the puddle, etc. Take it easy, build up several thin coats, allowing a half hour or more between applications.

 If you now notice some dings or defects, mix up a bit of spackling and paint, then apply it and wait a couple of hours before sanding. Then re-apply paint to entire structure.Do not be alarmed if the paint looks really crappy after applying. Provided that it was well-thinned, it should smooth out and obliterate small brush marks as the water gradually evaporates.

 Apply whatever trim you choose (trim tape or brushed on paint). There, you are done! ... Or perhaps not? If you want a shinier surface, and if you are not completely sick and tired of this project, you can go over the whole thing with another coat of polycrilic.

Now, we are done ... I think!

Aside: I have patched up "real" foam structures, such as some dings on a Fun Cub, using the spackling compound and paint technique. Generally, rattle can paints have a solvent that will attack foam. You can use them - clean the foam with alcohol, then paint it with polycrylic and let dry. Now, it is safe to spray with your rattle can. You can usually avoid the polycrylic step if you are very careful and only lightly spray, holding the rattle can at least a foot away from the foam, let it dry, repeat, etc. If the first coat was evenly and lightly applied, your plane should now be protected from additional spray damage.

41
General Discussion / Better Mousetrap?
« on: April 07, 2017, 09:08:55 AM »
Who said that you can't build a better mousetrap? Check out the link, below!

Such a contraption could be a more humane improvement to the "Bucket of Death" that is in the Playhouse now. A side benefit would be obtaining a pet or two. Or, some "take-out" for someone's favourite cat? Anyway, methinks that this is a pretty cool device!


http://digg.com/video/humane-moustrap-how-to



42
After having played with the Mobius and associated 5.8 GHz mount on my Fun Cub, I moved it over to the Opterra. The HeadPlay goggle system works well, so that I could give others a chance to see what things look like from the airplane's perspective.

I am unlikely to become a "real" FPV pilot, but that's OK. I am interested in experimenting and letting others see what can be done, simply and cheaply. Already, one of my "little friends" (as Jane calls them) has ordered up essentially the same gear, after trying out mine. Meanwhile, the other
"little friend" who did the inital scouting to find the equipment that we both bought, is setting up (I think) a Bixler with his gear.

 Last Sunday, I did some flights with the Mobius recording concurrently with transmitting. Meanwhile, Wilf took some video from the ground. And, several different guests had a chance to "ride along" via the HeadPlay, whilst sitting in a lawn chair (so they wouldn't get vertigo). After a number of hours of struggle, I managed to cobble together the following video. I hope you enjoy it. You may get a glimpse of Peter, Nathalie or someone else sitting near the videographer, enjoying a flight.

https://youtu.be/p1CLI6Dly3c

44
VIDEOS and PICTURES from KRCM Events and Activities / Amazing !
« on: November 26, 2016, 07:16:32 PM »
A couple of us were out at the Toyground today, enjoying a great flying session. We were in the playhouse getting the fire going (our encumbent OFS was a no-show today, but that's another story...). We noticed a strange object residing underneath one of the tables. I have attached a picture.

What evil genius put this contraption there? What does it do?

Well, we peeked into it and, voila!, one dead rodent floating around in a pool of water. Wow! Someone has invented a better mousetrap !!!

How does this thing work? Well, here is the scenario which we came up with:

 M.Mouse is out foraging and sniffs something ...
"What could that be? It sure smells yummy."
"Could it be peanut butter? I bet it is."
"Let me see, where could it be?"
"Hmmm... it seems to be coming from up there and if I just scoot up this handy plank, perhaps I can get it."
"Oh, oh, it IS peanut butter, spread all over that round thing over there. How to get it?"
"Well, I can just jump over to it, scarf down the goo and then hop back over here and go home and tell my little family all about this wonderful discovery."
"Here goes ..."
 1, 2, 3, clunk, splash!

"Help! Help! Help ... glug"

THE END


(We still wonder if this was Wilf collecting ingredients for an upcoming Chili Fun Fly.)

45
General Discussion / Starting a Jet Engine
« on: November 22, 2016, 09:55:35 AM »
Most of us don't get to do this, even with a model jet engine. The Embraer Regional Jet is depicted in this video. I hope you enjoy it:

https://www.youtube.com/watch?v=GzhdxSsoT0g&feature=youtu.be

A couple of things which most folks do not realize:

 - A typical jet engine uses in the order of 40% of the power generated by the turbine just to run its compressor.

 - A pressurized aircraft is NOT airtight, there is leakage from various places. Air is bled off the high pressure compressor (400 degrees F or so!) of one or more engines, passed through the intercooler (heat exchanger) and pressure reducing system, filtered, then piped into the cabin at a precisely regulated temperature and flow rate. Cabin pressure is controlled by constantly spilling air through the dump valve, near the tail. The entire volume of cabin air is replaced every minute or so. On the ground, after the doors are closed, the cabin is pressurized slightly above outside pressure and following takeoff it will be regulated to maintain specific, gradually decreasing pressure, eventually being held to the equivalent of perhaps 5000 feet above sea level (ASL). The aircraft may be flying at many times that altitude and therefore in air that is a fraction of that pressure.

 - You cannot open a door while the aircraft is pressurized. The doors are designed to seat into their frames from the inside. Next time you fly, observe how the door is opened and swings aside. They are mechanically locked but as long as the cabin is pressurized even slightly they will hold in place.

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