RE: ho229 wing profiles
You could also take a look for reports and magazine articles on a Horten IX built in Britain in the last three or four years and sporting twin gas turbines. I have had the privilege of seeing video of this and a twin turbo HP Victor in the air together filmed at a LSMA airshow. I learned just this last weekend that the Horten is no more, sadly. It was a most magnificent looking model. If you can contact the builder (I do not have it ) I believe that he did considerable research on the wing sections and the actual twist. No doubt he would be happy to share...
Posted on: 8/3/2004 1:19 AM by Author "probligo" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=2048817

RE: Induced Drag
Every time I see a photo of a Hawk, I drool. I have my dribble sheet draped over the k/b right now...and that is just from thinking about it. Actually elliptical dihedral is just the first step...now take those beautiful swooping tips and sweep them back, a bit like some of the extreme four taper rc gliders, and then a bit more... I have it in my eye, but damned if I can draw it on paper. Take it back and attach it to the wing? Nah!!! Remember the diamond wings and other attempts to avoid induced drag? Dont work for me, anyway. The most extreme version, and the one that comes from about three different computer models, is the "C Wing". Brilliant concept. but it don't want to turn corners apparently. Not good for ff, perhaps for sloping? <e> Actually, there is one thing that comes back to mind, and which is often missed in this discussion on induced drag. The last, and most easily overcome, generator of induced drag is the wing plan. Briefly, a straight plank generates most induced drag, a pure elliptical planform generates [b]ZERO[/b] induced drag. A straight plank to 60% half span, then taper to 80% root chord is about 40%, the multi-taper plan forms probably are close to elliptical - close to zero. This side of the argument - if I got it right - links [b]local wing loading[/b] with the amount of induced drag.
Posted on: 7/25/2004 1:42 AM by Author "probligo" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=2021024

RE: Induced Drag
Diverting just slightly... One of the things that confused me, and which took a while to get straight in my head is the relationship - Induced Drag > Velocity > profile drag. As I play round in the realms of ff glider, and this is right at the bottom of the drag bucket... profile drag is very low due to the low airspeed, and induced drag is high because of the "high" Cl numbers (typically 1.0 - 1.3). Consequently you see no modern F1x models with aspect ratios of less that 12 or even 15. The ideal solution, one which I am still figuring, would seem to be a polyhedral wing where the tip "fits into" the vortex at glide speed... [sm=idea.gif]
Posted on: 7/24/2004 2:27 AM by Author "probligo" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=2018725

RE: Sanding Block?
I looked at these myself and decided against using them. Why? The fact that they are flexible. If you want to get uniformity along a three dimensional shape such as a wing leading edge, then you should use something that will even out all of the humps and leave the hollows - like a long sanding bar. Hence I use a 30" and 15" sanding bar for solid hlg wings (the little fellas :D:D not rc ones ). If you use a pad it will follow the existing shape and tend to take near equal amounts off everything. BTW the same argument applies to sanding plaster skinned drywall. The guy who plastered our lounge out used a 1.5m x 0.2m sanding bar for exactly the same reason. Hope that helps. BTW I also use small blocks for finishing - like 1/4"mdf with 400 grit glued on for "polishing" sheet wings, down to "moulds" like those mentioned earlier. But they are fairly specialised...
Posted on: 7/22/2004 6:09 PM by Author "probligo" in the forum "Questions and Answers"
http://www.rcuniverse.com/forum/fb.asp?m=2014410

RE: tail length
No doubt there will be plenty of offers of fixed numbers for you to use. Go to the Aerodynamics board and search on "tail volume". There are a number of threads on the topic and there will be at least one that will give you the math involved. Essentially, the smaller the tailplane, the longer the distance between wing and tail...and vice versa. That is a very over simplification - there are many other factors as well. Take your time. Read, listen, understand and learn. Good luck [8D][8D]
Posted on: 7/21/2004 7:07 PM by Author "probligo" in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=2011347

RE: Flying wing?
http://www.b2streamlines.com http://www.sielemann.de/ (German but English also) http://www.zanonia-flyers.de/ (German) Zanonia is the home of the CO series - some of the hottest wings I have ever seen. Very good luck.
Posted on: 7/7/2004 4:19 PM by Author "probligo" in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=1969121

RE: RES Airfoil Selection
ooopppss
Posted on: 7/7/2004 3:38 AM by Author "probligo" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=1967646

RE: RES Airfoil Selection
What they said already PLUS - Take a long and hard look at the construction methods used by Drela for Allegro and BD. If you also take a look at what the freeflight (F1A ) builders have been doing over the past 10 years or more you will see where the ideas come from ;):D;) The [b]most important part of all[/b] is the main spar construction. [I} Flying Models International[/i] is a goldmine for current thinking in ff glider. The technology [b]does[/b] transfer well...Drela is witness to that.[sm=thumbup.gif] Second up is to listen to what Drela says about airfoil selection. How effective one particular airfoil is depends upon [b]accurate construction[/b]. I would add to that [b]pilot ability[/b] as a statement of the obvious rather than any implied criticism. (I can't fly my models.. I rely upon them flying themselves ;) )
Posted on: 7/7/2004 3:36 AM by Author "probligo" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=1967644

RE: Wing Joiner
Alternative - Measure joiner opening in wing as suggested. Measure depth of joiner using 1/32 wire or similar. Use these measurements to build a mould from suitable material (3/16 or 1/4 ply is good). Mould new joiner from a combination of cf unidirectional sheet and cf tow. Make sure that there is no more than 15% resin/85% carbon fibre. Use a thin moulding resin (not an adhesive). and get as much pressure as you can on the mould as quick as you can. There are plenty of sites out there on the net with pictures etc - check out cf prop moulding as a start.
Posted on: 7/3/2004 8:24 PM by Author "probligo" in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=1958624

RE: Need tricks on sanding down carbon fiber wing tube.
Again, amen to those who are saying "do not sand it..." A thought for you, and following from Sensai above, is to sand out the wing tubes. There are two reasons for this - one valid and one questionable... First - it will be a lot safer all round than sanding the cf joiner(s). I presume the tubes will be ali? If glass then go carefully as well to not cut the glass threads as well. [b]I WOULD STILL LEAVE THOSE TUBES SO THAT THE JOINERS ARE A FIRM FIT.[/B] That helps keep the wings on :D The second (this is something I have tried but not proven sucessfully) is based on a comment that was made to me some while back that cf tube [b]does not like point loads[/b]. IF THIS IS CORRECT then sanding out the tubes in the wings could be combined with relieving the tube ends just a fraction more to stop the point load at the joint. I repeat, this is to my knowledge conjectural and not fully proven and I for another would appreciate comment from those who know. <e> One thing I haven't seen mentioned... MEASURE FIRST, and work out how much difference you are going to have to take off the tube. It should be very little - like no more than a wipe or three with 400 grit wd paper... Is the wing root joint to the tube "blocked" with a thin layer of epoxy? Is there a simpler answer? as has been said - different sized tube (be careful with that as well because you do not want to under-spec it...:o:o )
Posted on: 6/29/2004 9:12 PM by Author "probligo" in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=1947100

RE: Stronger epoxy
From my experience, the [b]ONLY[/b] place for 5 minute epoxy is field repairs, where some positioning is required and ca would make a joint that is too brittle. I can also relate (from direct experience) that heat curing some of the 30 minute epoxies can make them stronger, but they also become brittle. In other words, failure is catastrophic where another slower joint might "give". If any epoxy is going "rubbery" or not curing properly, the first suspect is not the age of the product but the temperature where the product is being used. It is a sign that the epoxy has not kicked sufficiently to become exothermic (which it needs to for proper curing...that is also why the mix pot gets hot as the epoxy goes off). Check the product requirements [b]carefully[/b]. The epoxies I use (not West Systems) require minimum air temperatures of 17C. I prefer to warm the shop to at least 20C if I am making important joints. At that temp I have never had to warm the work or epoxy to get it working. Going back to the 5 min epoxy... If you frequently fly (and crash ;);) ) during winter a very good and handy little investment is a 12V hairdryer.
Posted on: 6/22/2004 7:12 PM by Author "probligo" in the forum "Tips & Techniques"
http://www.rcuniverse.com/forum/fb.asp?m=1926403

RE: Rib spacing
As Bruce has hinted, some more detail would help. Things to think about in making these decisions are - [ul] [*] Span [*] All up weight [*] Wing section (rib shape) [*] Lauch method [/ul] All of these have an impact on the forces within the wing and hence the size, shape and composition of the spars. Most of the wings I build have effectively only one spar. But its shape is essentially the front 1/3 of the wing. Take a look at www.charlesriverrc.org and Mark Drela's design for Allegro (the built up wing versions) to see what I mean. The way he builds his main spar and the "D" box leading edge is straight from freeflight gliders (where I come from...). By tying the leading edge, and main spar into a "tube" you are making one very large, very strong spar. I would not space ribs more than 75mm [b]on a large wing[/b]. Bruce is right coming down to 50mm for greater "accuracy". The problem of sagging behind the main spar can be solved by extending the sheeting further back. It is all compromise at that point.
Posted on: 6/21/2004 3:02 PM by Author "probligo" in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=1922204

RE: Scale olde non-lead sled
There are a number of plans for this style of glider available on the market already. Look for Sunspot, Thunderking, and Leprechaun. Sunspot was originally 13 foot span ff open glider, the others about 10 foot.
Posted on: 6/19/2004 6:42 PM by Author "probligo" in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=1917321

RE: Spoilers
If it helps, the biggest set I have seen were on a 16' span scale glider. The blades, top and bottom, were 1.5" deep and 30" long, made from 1/16 dural (aircraft grade no doubt - ex RNZAF). Full open, that glider stopped like it hit a brick wall. Mind you, at 2' off the ground and in full ground effect there was no other way of getting it on the ground either...:)
Posted on: 5/21/2004 4:11 AM by Author "probligo" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=1833638

RE: Help with C G
With a swept leading edge, I would be very careful not to get any further forward than Landi's suggestion. How does it fly at the "somewhere just forward of 50%"? I bet it is a bit "twitchy" and easy to stall. I would think that moving the cg forward by at most 2cm would help. Then test and trim and test...hand launching over grass - the freeflight methods - will tell you if something is drastically wrong at minimum risk. Suggest that you make a "balance machine" - mine is a pair of 10" long "hurdles" made from 4x3/16 sheet with a 1/4" long length of 1/8 square at right angles on the top edge. Gives me sufficient scope to mark le positions for each of my models to check that cg is ok after repairs, replaced batteries etc...
Posted on: 5/18/2004 4:43 PM by Author "probligo" in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=1825932

RE: Organic Design
Maybe there is hope for my brick sh--house building standards yet...:D:D:D
Posted on: 5/18/2004 4:32 PM by Author "probligo" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=1825901

RE: I am addicted now, this is nuts!
Welcome to the nuthouse...:D:D:D:D::D::D::D:
Posted on: 5/10/2004 8:17 PM by Author "probligo" in the forum "Beginners"
http://www.rcuniverse.com/forum/fb.asp?m=1803577

RE: Joining carbon fibre tubes - dihedral !?
Think about using 1.5mm birch ply dihedral keepers - like the old style ff models :D:D:D use two for each join, one each side of the spars, and epoxy in place. Run the keepers 2 ribs either side of the join. As David has said - it does not need to be incredibly strong. Just strong enough.
Posted on: 4/27/2004 5:22 PM by Author "probligo" in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=1764427

RE: HLG Control Rods?
Bob, Some of this "fancy" stuff is not as expensive as you might think. Teflon tube should be cents per foot at the right source. Carbon rod is used by the kite fraternity - follow up with them. a 1mm cf rod 3foot long costs me NZD15 so a price US7 would not be unreasonable... The most important thing seems to be whatever you use, get plenty of support for the link along its length, and allow for three dimensional movement in the ends... Look at some of the techniques used at www.charlesriverrc.org on the Drela gliders. 1/32 wire in teflon tube is the most frequent...
Posted on: 4/26/2004 4:59 PM by Author "probligo" in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=1760694

RE: !!! Composite Flying Wing !!!
Before you get too far down the track, see if you can get a hold of the AMI (Aircraft Modeller International) for March. There is an article in that on "ribless D-box construction". Now while this has been written for my speciality (F1A glider), it should not be difficult to adapt to the kind of model you are thinking of. I haven't read it yet - just returned home with it from LHS :):) - but the principles have been around for a while, and it is simply a matter of double skinning uni-d cf under woven cf. There has been mention in recent times of "co-weave cf and kevlar". I first saw this about 15 years back, in 6oz upward form, too heavy, no dang good for models. That product seemed to disappear - it was horrendously expensive as well. At the past Worlds the Chinese turned up with d-boxes on F1A and F1c models made from a similar product. So keeping an eye out in some of the specialty places on the web might be an idea as well. With good design. you could prove the combat nay-sayers completely wrong... good luck.
Posted on: 4/14/2004 12:55 AM by Author "probligo" in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=1721532

RE: Pics from tunnel testing
My guess is that the high tail is to avoid the problems that BAC had with the 1-11. On the BAC1-11, with deep wing stall all rudder and elevator control was lost due to the turbulence covering the after surfaces. By stickin em right up high like that any stall on the wing will [b]not[/b] impact on longitudinal control.
Posted on: 4/14/2004 12:40 AM by Author "probligo" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=1721499

RE: Flying wing airfoil???
http://aerodesign.de/english/profile/profile_s.htm
Posted on: 4/7/2004 4:25 AM by Author "probligo" in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=1698744

RE: RC "ultralight" glider
It is a neat idea. A mate of mine is using a cheap 2ch set with the rx strapped to the fuse under the wing. He uses that to drive the autoservos that he is using for circle tow / dt testing. Once happy with the setup he removes the rx and plugs the servos to the onboard electronics and goes flying...:D:D:D There have been a number of classic gliders converted to rc - one of my favourites is a Dutch model (Windkind from memory). Dates from late 1930s and lloks a picture - big (over 10feet span) gullwing with twin tails. On my long term must do list. Mate of mine has a fullsize "Sunspot" flying on 2 channel. Seeing that go up on a bungee is quite something...
Posted on: 4/5/2004 8:31 PM by Author "probligo" in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=1693864

RE: Free floating wing?
Thanks from me too for re-connecting me with this fascinating beastie. I first came across is about 4 years back on scaledcomposites.com. At that time it was one of their lesser presentations. So I guess that it has been around for a while. Always thought it would make a fascinating scale subject - at 1:1?
Posted on: 3/26/2004 4:03 PM by Author "probligo" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=1662747

RE: Tow hook for Zagi
I go with that. Just to add a little bit more to it - I have seen a standard hi-start used in similar fashion with 2M wings. The principle I am told is to get the wing (Zagi) to carry no more than the weight of the nylon line. It does not do the rubber much good as it is being dragged through grass, thistles, rock, mud, cowsh and all. The basic maneuvre is the same - power on, speed up, pull up...
Posted on: 3/15/2004 6:59 PM by Author "probligo" in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=1627853

RE: Paoli wing
Jim, I suspect that the colour pictures are intended to be illustrative only - to show how the cut portions are changed over to create the inverted surfaces. I have seen a number of Paoli's articles and never once have I seen him divert from the 90* to airflow / ribs idea. BTW, which ff (wing) gliders have you built? I have my second try at Jenne's "Piccolo" under trimming at the moment. Must pull it out this weekend...weather permitting.
Posted on: 2/8/2004 10:09 PM by Author "probligo" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=1509886

RE: O.S. rotary engine -Weinkel-
Heh...talk to Rod Millen about Mazda RX's - how many times did he win Pikes Peak? 14? 12?[8D][8D][:)][8D] <edit> Sorry I did not mean the implication that he had won Pikes Peak that many times in a Mazzy Wan*** ;) But he was certainly King of the Rotary here in NZ and had at least one Pikes win with his version of the RX7.
Posted on: 2/2/2004 6:32 PM by Author "probligo" in the forum "Tips & Techniques"
http://www.rcuniverse.com/forum/fb.asp?m=1491227

RE: canards v. forplane
[8|][sm=spinnyeyes.gif]Errr FH, I said that???? You are absolutely right - that is why my ff canard has the foreplane at +7* and the wing a 0* To the world at large - sorry. Take out the "not" and it makes sense.
Posted on: 1/31/2004 2:37 PM by Author "probligo" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=1485153

RE: canards v. forplane
No doubt someone will correct me if I am wrong... The maneuverability of a canard must (I think) be directly a function of the ability of the foreplanes to carry a wide range of loads.... So if I give up elevator, the effect is to try and shift the cg around the centre of lift (MAC I think would be more correct. This means that the lift being generated by the foreplanes must be increased. In the instance given by Combattpigg obviously the foreplanes that he was working with could not generate that increased lift so, in his words they became more airbrake than control surface. The two rules that I have been given (from many years back) are - The foreplane must not stall before the mainplane The foreplane must be capable of generating more lift [b]per unit area[/b] than the mainplane. The vector equilibrium for a canard has the foreplanes carrying considerably more ( a greater proportion) of the total lift load than does the tailplane on a conventional aircraft. For that reason, the conventional thinking about tailplane size and lift has to be seriously abandoned if you are to get a canard to fly. BTW I think (MHO) the Quickie is a canard. BTW2 Canard is the [b]aircraft type[/b] Foreplane is the [b]part of the aircraft[/b] But that is just me being pedantic. Does it really matter?
Posted on: 1/31/2004 12:33 AM by Author "probligo" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=1483980

RE: Lindberg Delivered Letter 1928 - Value?
I am definitely no expert here - but from my museum administration experience... You are going to need some fairly water-tight provenance for the letter- who is it to, does it have any identifiers that indicate that it is being carried by Lindhberg, is there evidence that he carried mail, is there evidence of who that mail was addressed to or sent by, is there documentation accompanying the letter giving the details of where, who and when it has been owned by since. If you have any or all of that then it will help the value of your letter. I suggest first, before you advertise it, that you take it to an expert in the field of "antique letters" and ask them for advice.
Posted on: 1/25/2004 2:00 AM by Author "probligo" in the forum "Golden Age, Vintage & Antique RC"
http://www.rcuniverse.com/forum/fb.asp?m=1464227