|
RE: found this interesting discussion on Spiral Slipstream
[quote]THE JET ROTATION IS NEGLECTED! So much for the slip stream rotation being important in the design of a propeller! Happy weekend [/quote] Yes, You are right.......BUT, reread the text and what you even quoted, especially the part I made red. I don't recall anyone ever being concerned with design of the propeller in relation to the spiral slipstream. It is the AIRFRAME the propeller is bolted to that is designed with the spiralling airflow in mind. EG, leading edge of the fin offset a degree or two, bit of right thrust, whatever. It is the ability to calculate the spiral that allows those adjusments to be made to said airframe. Look in a ducted fan at the design of the stator vanes. You will notice that they are almost always at an angle to the straight through airflow and curved like a old timer free flight airfoil.. Why is that??? Simply because the airflow does NOT flow straight through the duct. It comes off the fan on a spiral. Since it can be calculated how much "angle" there is to that airflow, the can put those stators at the right angle to most effeciently "capture" and straighten that airflow. If the spiral slipstream was a myth, there would be no need for even bothering to put the stators in there, other than to support the motor.
Posted on: 9/8/2012 2:04 PM by Author "rhall999"
in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=11221997
RE: Scratch Designed/Built Sailplane Fuselage
I'll be watching. Really enjoyed the first two, especially the rebuild of the wing. Personally, I liked the original fuselage profile the best. It looked the sleekest and the neatest. But, since you asked, out of the new ones, I like B because it is the slimest, and sleeker of the bunch, and I like E because it looks like a bird.
Posted on: 9/4/2012 2:51 PM by Author "rhall999"
in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=11217443
Quick scratch built sloper
So my father-in-law calls me the weekend before the Labour Day long weekend and says he and the mother-in-law are coming up for a grandkid fix on the long weekend. Then he tells me that he is going to bring his Multiplex Easy Glider (motor removed, turned into a sloper) to try out our hills up here. Trouble is, I don't have a slope suitable glider in my inventory. So....last Monday (Aug 27) I stumbled upon a large chunk of pink styrofoam at work, left over from builing "toolbox organizers" for the shop tools. So, I brought it home with me that night, dug out the good ole' hot wire and started building. The goal being to have a flyable glider by the time the old guy got here on Friday night (Aug 31). Well, By the time he arrived, All I had left was to hinge and attach the ailerons and install radio gear. We flew it Saturday afternoon (Sept 1). It actually flies really quite nice for a thrown together in 5 days airplane. Of course after all that there was no wind whatsoever on Saturday, so we also quickly installed a hardwood block in the nose and a towhook so we could tow it with the Kadet Seniorita. Sunday however the wind blew and we got to try'er out on the hill. Here are the Specs: Profile Schweizer 1-26, done in "that looks about right" scale. Wingspan 64" Construction, pink styrofoam, balsa and light ply. Weight, not sure.....fairly light. Controls, ailerons and elevator. Programmed in some flaperon mix for fun Radio, Hitec Optic 6, supreme reciever, HS-81 servos.
Posted on: 9/4/2012 2:18 PM by Author "rhall999"
in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=11217382
RE: Sailplane Wing Design Round II
[quote]Yeap seems I learned that the hard way. Its interesting that in therory, reinforcing just a small section of an otherwise sound wing could actually cause it to fail.[/quote] Yup, or the other thing that I have seen happen is that there will be a failure point on a structure, so a brace/doubler is added, and the failure point just moves to the end of the brace/doubler. In the full size aviation world, the Citabria family had such an issue with the spar. An Airworthiness Directive was issue to addres the issue, and doublers were added/modified. Now there is another airworthiness directive to inspect the spar at the ends of those doubles as the crack location just moved. The best solution with those is similar to what you are doing, a completely different spar, in the Citabria case it is a new metal rather that wood spar. I really like the "second" spar idea in you pictures. Like you mentioned, to keep the wing aligned using two piece ribs would be tricky. Besides, if you use one piece ribs, and then just make your shear webs so they fit nice and snug enough between each rib, the end result really won't be any weaker than the solid spar/split rib design. Especially with your carbon spar caps. This time around I doubt you will have any issues!!!
Posted on: 5/31/2012 2:06 PM by Author "rhall999"
in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=11101567
RE: Sailplane Wing Design Round II
Hi again Nodd. Boy that glider sure did turn out nice. Beautiful sleek lines!! Too bad you had a wreck, but that happens from time to time doesn't it Anyhow, I don't know it this will be of any help to you, but when I built my enlarged Sagitta wing (111" span, pictured below) here is how I did it: The spar caps, top and bottom are 1/8 X 3/8 spruce, the shear webs are progressively smaller. They start the full width of the spar caps near the root and go down from there. All this is combined with a full D-tube leading edge structure. The only place where I wrapped the spar with anything was at the root, the section that has the joiner tube inside it. This is simply because as you put a G load on the wing, the tube is actually trying to "pry" against the spar caps and spread them apart. Outside of that point there is significantly reduce force trying to spread the spars apart, and the bond between the spar caps and webs is enough to do the job. This wing will go up on a high start that is big enough for 3-4m gliders and the wing barely even flexes. Even crash tested it a couple weekends ago.....no damage to the wing after two gust wind cartwheel landings!! Just looking at the photos, I am with Bruce, I would bet that the shear web on the original wing was the major player in the failure. EDIT: Forgot to say, the following is not directly aimed at Mr. Nodd, as he is pretty knowledgeable in designing, but more intended for newer fellow's to designing and building. Something to watch out for, are "built in sheer points". In other words, a place where there is a change in the structure that could cause a failure. A good example of this is the end of a joiner tube, or the end of a double, or maybe even the edge of the top sheeting. Any of these points will be a spot where there could be a failure. A perfect example of this is how in a crash, most aircraft will break the fuselage right at the trailing edge of the wing/wing mount structure. What you want to do to alleviate those shear points is spread them out. If you have the joiner tube, the root spar doubler, and the sheeting all and at the same rib, immediately followed by the small sheer webs, I guarantee that is where the wing will break. Some things I did on my wing was the leading edge sheeting of course extends to the tip, so that helps spread that out a bit. The ply doublers on the front and back of the spar caps go out to the end of the joiner tube, but are then cut at an angle from the bottom up so that the top of the ply is one bay longer than the bottom, allowing that shear point to be spread a bit. Also, right up against the joiner is where the shear webs are full spar width, thereby helping to spread the heavy loading out along an even greater length. Remember, this is pretty basic stuff, but many guys forget it......the closer in to the fuselage you get, the stronger the bending loads are on the wing. One needs to build accordingly strong at the root, and get lesser towards the tip to keep the tips light where there is less load. Here are the promised pics of the glider, and a simple "schematic" drawing of the spar structure.
Posted on: 5/30/2012 4:11 PM by Author "rhall999"
in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=11100473
RE: Scratch Designed/Built Sailplane
AWESOME Nodd!!! It looks really nice all finished in the transparent red and white. Looks like it flys as nice as it looks too. Excellent work!!
Posted on: 5/13/2012 10:19 AM by Author "rhall999"
in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=11079195
RE: Scratch Designed/Built Sailplane
Nice to hear your feeling better Nodd. Scotch tape for hinges.....that is a neat idea. My first thought was that it wouldn't stick "permanently" enough. Then, I thought about the number of times that I have used that exact same stuff for a quick field repair of holes in monokote, and how hard the tape is to get off later. Now I am thinking I just might have to try that on my next glider. Probably won't work real great on my Goldberg Ultimate bipe I'm building though.......but as a hinge gap seal.....hmmmmm.
Posted on: 5/4/2012 8:17 AM by Author "rhall999"
in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=11068165
RE: Scratch Designed/Built Sailplane
[quote]An excellent question which unfortunatly I have no answer for just yet. I do have a few ideas though. We'll see.[/quote] Well, you'll just have to let us know later when you decide Personally, I can't wait to see the completed photos. It is going to look great!! [quote]Nice Kadet. Yeah some of the guys I fly with are into the aerotow thing. I'm planning to attend the New England Aerotow 2012 next month. Trying to get my 4m Discus ready for that. Will probably bring this plane with me too as they allow motor-gliders. Should be fun.[/quote] We haven't gotten into serious glider towing and gone to big events. We have just been doing it for our own enjoyment with our smaller stuff. It is really quite a lot of fun.
Posted on: 4/30/2012 4:21 PM by Author "rhall999"
in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=11063147
RE: Scratch Designed/Built Sailplane
Sorry Nodd, we are heading slightly off topic for a couple minutes [quote]Nice Rhall999! Is that a Hoerner wingtip you have on the green airplane? What are the specs? [/quote] Hi Flyer, that there green machine is a just good ole' Sig Kadet Seniorita kit, somewhat modified. It was made a taildragger, ailerons were added, went to a bolt on wing. The drooped STOL tips were hand carved/sanded
Posted on: 4/30/2012 3:35 PM by Author "rhall999"
in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=11063077
RE: Scratch Designed/Built Sailplane
[quote]I'm trying something new on this model. I usually use CA hinges but I noticed one of my ARF gliders uses just the covering its self as a hinge joint. The result is a gap-less joint that's fairly sturdy & doesn't seem to bind at all. If my ruddervators start to fall off in a month or so I guess its back to CA hinges but my other glider has been around for years & no signs of hinge fatigue yet. So I thought I'd give it a try. Here's how my hinges are laid out...[/quote] First off, let me say that you have built one heck of a nice looking glider!! Now, if it makes you feel any better.....I have been using that "covering hinge" method for quite a few years. When done properly it is a superb, trouble free system. To reiterate what Bruce said, it is best on slower aircraft such as gliders and park flyers, and you will have no problems with yours at all. Now, just to show you how well they can stand up even on an aircraft that is able to fly a bit faster and put more loads on the controls................ This nice green airplane does not have a single "proper hinge" anywhere. Every control, ailerons, elevator, and rudder, are ALL done with the exact system you show above in your diagram. After 1 full season of hard flying, including a bunch of glider towing.
Posted on: 4/30/2012 2:46 PM by Author "rhall999"
in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=11063001
RE: first glider
You will never regret your decision to try gliding. That first time you hook a thermal and climb even 100 ft you will be hooked. Then you will be trying for more and more time and altitude, and having an absolute blast doing it!! As for a basic glider, I agree with Bruce, just a simple rudder/elevator glider is the way to go. I have never personally flown a Radian, but I hear they are great. If you want to build, find a good ole' Gentle Lady, Sig Riser, Olympic II, GP Spirit etc, and put it together. All of the above can easily be "electrified" if you want a powered glider instead of pure glider too.
Posted on: 4/28/2012 8:39 AM by Author "rhall999"
in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=11060121
RE: What green is this?
Just for comparison sake for you, here is Monokote transparent green on a Kadet Seniorita. It is a darker shade of green than the Ultracote, but it really looks great in the sun. The other thing to keep in mind though, is the transparent monokote is really hard to work with lately, and I have read that the green is the worst of the bunch.
Posted on: 4/28/2012 8:31 AM by Author "rhall999"
in the forum "Kit Building"
http://www.rcuniverse.com/forum/fb.asp?m=11060108
RE: found this interesting discussion on Spiral Slipstream
[quote]I hope you didn't use the pictures as proof of spiral slipstreams. The vapor trails in the pictures show where the prop tips that are producing those stationary trails have been as the airplanes taxi.[/quote] Da Rock is correct Ranier. What you are seeing in the Hellcat and Transall photos is essentially the "wingtip vortices". If you have ever gone to an airshow and watched a modern fighter jet, you can see white vapour trails coming off the wingtips in high G manuevers. Basically all that is (from my understanding), is the low pressure in the center of the wingtip vortex that is cooling and condensing the moisture out of the air into a visible vapour trail. The pattern you see coming off those props is exactly the same thing, the center of the "wingtip vortex". Last week I did a bunch of research on this spiral slipstream for this thread, to try and find as much info as I could for those that do not believe it exists. In that time I found a few different research papers that indicated that the spiral flow originates further inboard on the blade, where the blades are wider. [quote]As for calculated spiral - gimme a break -[/quote] I guess you never actually looked at those links I posted. Seems to me that it is pretty clear. Complicated bit of math, but nonetheless it can be calculated. The one paper was written by a Dr. Eppler and Dr. Hepperle, two pretty well known and respected aerodynamicists.
Posted on: 3/16/2012 10:39 AM by Author "rhall999"
in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=11002799
RE: found this interesting discussion on Spiral Slipstream
Spiral Slipstream calculations found!!! Yes, I seem to have too much time on my hands Anyhow, I have found not one, but 2 papers in which there is a mathematical formula to calculate the angular momentum....or rotation....of the propeller slipstream. http://www-mdp.eng.cam.ac.uk/web/library/enginfo/aerothermal_dvd_only/aero/propeller/prop1.html http://www.mh-aerotools.de/company/paper_1/epplerhepperle.htm Enjoy!!
Posted on: 3/8/2012 1:12 PM by Author "rhall999"
in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=10991765
RE: found this interesting discussion on Spiral Slipstream
[quote]Same phenomenon. The vapor trail and the bubbles are right where the prop tip created them. They are particles/objects left behind, right where they were created. They show you where the prop tip was as it passed through.[/quote] Well, without wanting to sound rude....did you even watch the first video I posted of the boat prop?? I only ask because in that video, the bubbles are nowhere near the tips of the prop, they originate out of the hub, and start to swirl well aft and inboard of where the prop tips are. In fact, right at the "start and end" of the bubbles, you can see that right near the center of the prop is where they start their swirl. In this case, the "vortex" at the tips in which you are referring to is definitely not what we are looking at. I have been fortunate enough to have seen that on full size Dash 8 and Dehavilland Twin Otters at the airport where I work
Posted on: 3/8/2012 12:23 PM by Author "rhall999"
in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=10991717
RE: found this interesting discussion on Spiral Slipstream
Stumbled upon another neat one. This is a video of airshow pilot (and R/C pilot too!!) Skip Stewart flying his highly modified Pitts. In this video there is a very short...only about 2 seconds....example of the swirling slipstream. As it is pretty brief, you need to watch closely, in fact I had to watch it 2 or 3 times to be sure. If you skip to the 6:00 mark in the video, Skip is performing a torque roll. Just as the airplane stops climbing, he switches of fthe smoke, so it forms a nice cloud behind him. Then, as the airplane start to back up into the cloud, right around the 6:12-6:15 mark, you can see the top of the smoke cloud all of a sudden start to fairly rapidly rotate, in the direction of propeller rotation. Once the airplane gets into the smoke and all kinds of other strange air movement from a sliding backwards airplane takes over. you can not see it anymore, which is to be expected considering what is going on. Check it out, the important part starts around 6:00 http://www.youtube.com/watch?v=ST0rhX0BKiE
Posted on: 3/8/2012 9:14 AM by Author "rhall999"
in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=10991488
RE: found this interesting discussion on Spiral Slipstream
Well fellas I'm no expert, I will admit that. But if you can not see the bubbles swirl right aft of that boat prop, maybe you need your eyes checked. Granted, the prop rpm is pretty quick, and the bubbles swirl pretty quick, but the presence of the swirl is obvious. I found an interesting report by Dr. Michael Selig on R/C airplane props, and it makes mention a few times of the "swirl" in the slipstream. Here is the report. (Incidentally, I found a few reports exploring the slipstream effects on V/STOL aircraft, and how the slipstream affects the wing, interesting but extrememly technical reading....made my head hurt!!!) http://www.ae.illinois.edu/m-selig/pubs/Selig-2010-AIAA-2010-7638-PropAeroSim.pdf [quote]My reasons are simple, and backed by empirical experiment. Observe the smoke injected into the prop slipstream on any IMAC/fullsize aerobatic aircraft and see if you can observe any 'spiral flow'. Stick a pin and a long bit of cotton just behind your own models engine, and see if you can detect any spiral flow.[/quote] When you are looking at the smoke, keep in mind the volume of air blowing the smoke straight back due to the speed of the aircraft even on the takeoff roll. To really be able to see the smoke follow any sort of spiral from the prop, it would need to be under a very high power setting, at a very slow airspeed or basically stopped.........NOW, on that note......... I also found an interesting video of Sean D Tucker flying his Challenger biplane. Most of this video was taken from another aircraft. Now, there is a chunk of this video that is of particular interest, and that is from about the 00:30 to 00:45 second mark. In that section Sean has the aircraft in his hover, and the camera aircraft passes around behind. You can see quite nicely the flow pattern of the smoke. Take note which side of the horizontal stab is obscured by smoke, and which side is not. Near the end of that segment, observe the smoke pattern, as the smoke on the left side of the aircraft rises considerably higher than the the tail. Meanwhile, the smoke on the other side stays almost "flat", almost in line with the trailing edge of the wing. For those who don't know, the prop on this airplane will rotate the same as most model airplane props, in other words, clockwise when viewed from the pilots seat. http://www.youtube.com/watch?v=H8nKzviskUM&feature=related Another interesting video I found is someone testing their R/C Yak 54 smoke system. Watch the smoke pattern here as well, and you will see that the left wheel is obscured by smoke, and the right is not, indicating the smoke is being sent to the left a bit......which is consistent with the "spiral slipstream theory". If you watch closely,you can also see the smoke behind the left wing begin to curve upwards an da little bit back towards and over the tail. I thought at first that perhaps there was a wind blowing when this guy was doing his test, but watching the smoke farther back behind the tree, that does not appear to be the case. http://www.youtube.com/watch?v=lDNreZke7iM Anyway, like I said, I am not an expert, but there is enough evidence in favour of the spiral slipstream for me
Posted on: 3/7/2012 7:49 PM by Author "rhall999"
in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=10990551
RE: found this interesting discussion on Spiral Slipstream
[quote]Guys for the spiral to be true the propeller has to induce airflow in the same direction as the rotation of the propeller. If you watch the video again, you can see the direction of rotation right at the start of the video. I admit, it is hard to tell with the bubbles, but sure looks to be the same direction to me. This is the same as saying, if we place a probe somewhere below and aft of the trailing edge of a wing, we will find air moving in the same direction as the airplane. Never heard that one taught either. Can't say as though I have ever seen evidence of that in any wind tunnel tests either....but I could be wrong. There definately is some "forward" moving air below and aft of the LEADING edge. As to the exhaust bubles from the prop. still not proof the bubbles are acually spiralling in the prop's wake. Really??? Do you honestly think that there is something else there that is causing the bubble to spiral, and what would such a thing be?? The boat is barely moving, and you can sort of see the flow pattern off the back of the boat hull by watching the seaweed stuck to the bottom, and other floating particles in th water. [/quote] See my comments above in red. I hate to be rude Major, but it seems to me as though you are grasping at straws now, trying desperately to cling to your theory Just kidding, I know how hard it can be to accept things sometimes when your brain is certain of something else, I can be pretty stubborn myself sometimes!!!!!!
Posted on: 2/28/2012 7:51 PM by Author "rhall999"
in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=10980827
RE: found this interesting discussion on Spiral Slipstream
[quote]Actually the prop-stream has commonly been used to help generate a roll-force to the right. Free flight modelers have been doing it for decades. The tall pylon used to mount the wing was incorporated to position forward, side-area in the prop-stream to help counteract the engine torque and to moderate the severe (often fatal) left turn (spiral dive) that had previously been encountered during the power-on phase. An additional feature for reducing the power-on left turn was the use of a sub-fin to position more of the vertical fin area below the engine thrust-line. They also found that moving the entire fin to the bottom of the fuselage would generate a power-on right turn. The bottom fin however would reduce the flight score because it touched the ground sooner. Then evolved the very-high-thrust-line configuration with the engine and wing mounted on top of the pylon, and the fin mounted on top of the fuselage; to generate the power-on right turn.[/quote] Huh, well isn't that cool, thank you gyrocptr!!. I did not know that. But then, all of my free flight planes back in the day were just sport rubber power or slingshot launched gliders. Never got into any competition stuff beyond me and dad seeing who's plane flew better. But, it still goes as more evidence in favor of the the spiral slipstream theory
Posted on: 2/28/2012 5:37 PM by Author "rhall999"
in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=10980672
RE: found this interesting discussion on Spiral Slipstream
Couple of quick comments. First, MajorTom, I read through your previous thread on propeller myths when it was active, as well as the thread linked by gdaddy. I notice one of your biggest arguments is that there should be a roll in the opposite direction (to the right). Look at a top view of an aircraft, and see how much wing area is in the prop wash, percentage wise......not very much right?? Notice also that the small percentage of wing that is in the prop wash is right at the root, therefore not much leverage. Also not that on most low or high wing aircraft, most of the propwash passes above or below the wing, therefore not a whole lot of the propwash actually affects the wing. Now look at the percentage of the tail that is in the propwash, quite a bit more. Also note that the tail is generally fairly centered in the propwash. And finally, look at the leverage that the tail has to push the nose from side to side. As for why the spiral on the elevator doesn't make it roll, well, remember, it is fighting against the whole wing again, same as the slipstream that does affect the wing. Second, I work in the full size helicopter business. When our pilots are slinging a load on a long line, they quite often need to put either a swivel in the line so that it does not get all twisted up, or use some sort of "stabilizer" to prevent it from spinning in the first place. Sometimes, it is as simple as a longer line so the load is not affected as much. Now, I found a cool video you might like to see. Probably will erase, or at least drastically reduce any doubts, check it out: http://www.pond5.com/stock-footage/142398/rotating-boat-motor-propeller-prop-as-it-moves-through-crystal-clear-water-un.html
Posted on: 2/28/2012 4:00 PM by Author "rhall999"
in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=10980539
RE: Cambridge scientist debunks flying myth
Well, I got into it pretty good over on RCGroups with Tim, (my user name there is stardustertoo) so I am not going to get into it here again. But, I have come to a conclusion of my own........ Comanies such as Boeing, Northrop, Airbus, NASA, and many others have all been using basically the same research and findings as to how wings work for years. All of these companies have many succesful aircraft flying worldwide, every day. Dr. Mark Drela has designed some incredibly succesful R/C gliders and airfoils, and maybe a lot of other "airfoil related" stuff, I don't really know. Dr. Michael Selig has also designed/drawn a whole whack of very succesful airfoils for all different uses. Mr. Don Stackhouse (DJ Aerotech) has been involved in the design and building of many different types of propellers, and has designed numerous succesful model aircraft. As far as I have been able to find, all of the companies/names above have a couple things in common: #1-They are all very succesful in getting machinery to fly. #2-As far as I can tell, they all design based on the principle of differential pressure lift, not so much downwash. **See note below So, the conclusion I came to........why not listen to the guys who have PROVEN that they know what they are talking about. Why not listen to those who have put their theories to the test and succeeded. Why not take the knowledge gained by years of experiments and actual flight testing, and use it. As I do not have the resources to do that kind of testing on my own, well, their's will have to do. But, thats just me. **Note: the differential pressure lift I refer to is NOT the incorrect "equal transit time" and "Bernoulli" theories that have already been put through the wringer. I am talking about the real differential pressure, the turning and accelerating of the airflow caused by the wing passing through the air. Also, note that none of the names mentioned above have ever denied the existence of downwash either (at least to my knowledge anyways). It is just that some folks know that the relationship between downwash and diff. pressure is extremely complex, and you pretty much do not have one without the other.
Posted on: 2/8/2012 1:00 PM by Author "rhall999"
in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=10950065
RE: Sig Seniorita vs. Mini Telemaster
Hey Jolly, go for it!! A friend of mine did exactly that a few years ago. He used 2 old OS .48 Surpass FS engines. Boy did it fly nice. He also enlarged to vertical stab and rudder for better control in the event of an engine out. It flew so well on one engine that just to prove a point to a guy one day, he only started one engine, took off, flew it around for a while, and landed. The other guy was pretty shocked!!
Posted on: 1/22/2012 11:32 AM by Author "rhall999"
in the forum "Kit Building"
http://www.rcuniverse.com/forum/fb.asp?m=10921572
RE: Sig Seniorita vs. Mini Telemaster
[quote]Nice flames.[/quote] Thanks, I had fun with it. The ones on the wings turned out better than the fuselage, But I like them all. One of my flying buddies said I put them on backwards, because I like to go out on windy days and fly it backwards
Posted on: 1/21/2012 9:41 AM by Author "rhall999"
in the forum "Kit Building"
http://www.rcuniverse.com/forum/fb.asp?m=10919961
RE: Sig Seniorita vs. Mini Telemaster
Here we go....
Posted on: 1/20/2012 1:42 PM by Author "rhall999"
in the forum "Kit Building"
http://www.rcuniverse.com/forum/fb.asp?m=10918954
RE: Sig Seniorita vs. Mini Telemaster
I love the good ole' Seniorita. My first one was stock, except for being a taildragger. My second one (pictured below) was modified with ailerons, bolt on wing, taildragger, drooped STOL wingtips (mostly for looks), narrowed down aluminum LT-25 landing gear, and the engine is upside down for a nice clean looking front end. Powered by a Saito .30.Can't say anything about the Mini-Telemaster, never seen or flown one. [quote]Could either of you supply any drawings and or information on how to go about adding the barn door ailerons[/quote] As far as the ailerons go on mine, I built the wing as per the plans, and then measured out ailerons that "looked about right" and cut them out of the wing. Then, I added a strip pf 1/4" balsa to the trailing edge of the wing ribs to give the ailerons something to hang on to. The leading edge of the ailerons were timmed to about a 30° angle, and another 1/4" strip along the front of the aileron. Added a small balsa "sub rib" on each end of the aileron and aileron bay to give the trailing edge stock some support. For a hinge, I just covered the wing, and the used an extra strip of monokote, top and bottom, as the hinge. They work great, it rolls about as fast as any sport aerobatic job!! All of my engineering for the ailerons was done using the tried and true "that looks about right" formula. One neat thing with the drooped STOL wingtips, is that they supossedly assist in keeping the airflow staighter along the bottom of the wingtips, so I still have strong aileron authority right down to the stall. edit, pictures didn't work, I will try again.
Posted on: 1/20/2012 1:39 PM by Author "rhall999"
in the forum "Kit Building"
http://www.rcuniverse.com/forum/fb.asp?m=10918949
RE: take that not so good arf out of the box and make it into something better
This is a neat thread. I am also a good ole' fashioned builder myself. I thought I would throw in a picture of my ARF bashing job a while back. Came out of the box looking like this, http://www.greatplanes.com/discontinued/gpma1365.html Finished up looking like this: (see picture) Modified the rudder for scale appearance, different colour scheme, a couple of other minor changes.
Posted on: 1/20/2012 1:07 PM by Author "rhall999"
in the forum "ARF or RTF"
http://www.rcuniverse.com/forum/fb.asp?m=10918915
RE: Lets see YOUR crazy design
Here is one for ya. This is a set of Piper Cub tail feathers that a couple of us hacked out of foam one day. We gave it some small elevons at the trailing edge, stuck a .15 on the front, and flew it!! The black hinge lines are just drawn on with felt pen for "scale effect", the actual hinge lines are further aft. Somewhere, we have a video of it flying, but I don't know where. It is actually surprisingly stable and gentle to fly.
Posted on: 12/27/2011 2:50 PM by Author "rhall999"
in the forum "Questions and Answers"
http://www.rcuniverse.com/forum/fb.asp?m=10878509
RE: Interested in tow-release gliders
My only concern with the 4-star is the speed. But, the Easy glider having a flat wing and ailerons it shouldn't be a problem. A polyhedral, rudder/elevator only glider you would have trouble. Now, the suggestion of a Sr. Telemaster for a tug, that is super!! Built nice and light, they can fly slow enough for the small 2 channel polyhedral type gliders, and yet big enough to handle larger ones too. I went with the Kadet Seniorita for 2 main reasons, #1, I just happened to have had a kit handy in my closet, and #2, I just really like the way they fly even just for fun flying. Besides, the fancy modified Sagitta 900 in my other thread is the biggest glider I will need to tow anyways. Tailies, had a look through your site just a few minutes ago.....very nice!!! Lots of good info there, well done.
Posted on: 12/8/2011 9:08 PM by Author "rhall999"
in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=10851004
RE: Interested in tow-release gliders
[quote]the Multiplex Easy Glider is an excellent sailplane to learn aerotowing with. It is very durable and offers great flight characteristics at the same time. Here are some recommendations I put together for aerotowing[/quote] I will second that. We had great success with the Easy Glider this past summer. Come to think of it, if you were careful, you might even be able to tow that with your 4-Star 60....I think.
Posted on: 12/8/2011 8:39 PM by Author "rhall999"
in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=10850976
RE: Interested in tow-release gliders
[quote]I like the idea re "turning" in the opposite direction. Will give that a go; it seems to make sense. We had some drama, once, when the tug pilot did a sloppy, descending turn ... glider sped up, of course. Then wham! [/quote] Yup, "then wham", the fun begins!!! We actually learned the "turn the other way" trick from my dad. He flew full size gliders and towplanes back in the 1970's. What they did then (and probably still do) is when entering a turn, the glider pilot points his nose at the towplanes outside wingtip, and then follows the towplane around the turn like that. With the models you can't see that from the ground, so we just modified the technique to "turn opposite the tug". Works quite well. My brother-in-law's first time glider towing he didn't know this trick, and we accidentally forgot to tell him, we just assumed he would figure it out. Wrong, takeoff, climb out, start first turn and sure enough, he turns inside the towplanes arc......very shortly after ....wham!! That is him getting ready to launch the blue and orange Spirit in the pics in the other thread I linked. I am the other guy flying the green Seniorita.
Posted on: 12/8/2011 12:41 PM by Author "rhall999"
in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=10850123
|
