Wonderful illustration of sensitive dependence! Can you please confirm: Is the only difference between the two superimposed videos that you cut the string with your left hand in one video and your right hand in the other video? In other words, as best you could control things, the starting places were exactly the same. Did you use the same pair of scissors each time? Thanks!
Yeah, same scissors, everything as close to the same as I could manage. Tied up with thin cotton and left to settle down for a minute or two before cutting. Don't know why I used different hands though! Different gravitational field!
I have to say, those first launches were not required after a couple it should be obvious that balance WAS the problem. I build a lot of gliders and testing should have been without any power. If the balance is good, it will glide. Once glide is good, apply power. Anyway, you worked it out obviously but ouch to those first launches. A testament to a strong airframe. Well built.
I have build mine a while ago and just can't get it proper in the air. Power enough but it won't turn using the ailerons, it is Just effectiv only with the rudder. So at the moment coverted it just to rudder and elevator and moved the cg a back forward, still hoping to get it in the air, because was a lot of work and be honest one of a kind on the field. Build it from the Bernard Gross plans and around the 3 meter span
That's strange, as mine turned quite well using ailerons (elevons really). Although I did use an aileron to rudder mix; have you tried that? 3m is quite large! Good luck.
A big flying wing can be a dog. The wings have to be rigid. I have a Multiplex Cortina kit and I'm still pondering over preparing the wings before finishing. At over eleven feet, the span and sweep like the Bernard Gross Wing, is a challenge and balance is of course the real trick. Slope versus Thermal, Hand launch versus Aerotow, Winch or Bungee, all need consideration.
bonjour ami modéliste . j ai bien trouvé le plan. merci ! je suis en train de le reproduire. j aurais juste une question.....j ai du mal a voir si le profil a l 'emplanture possède une double courbure a l' extrados..... profil spécifique aux ailes volantes i am sorry...i dont speak english thank you very much
There is almost no reflex (the upward curve of the trailing edge on flying wing airfoils) at the root. The stability comes from the tips- they are reflexed relative to the root. I took a photo but there seems no way to post it here. I don't speak French so I used google translate.
@@marinimatteo9536 It was my first elliptical wing: I made the trailing edges too small at first and had to beef them up after they warped when covered. I think one rib wasn't drawn and I had to interpolate it. There is a thread at www.rcgroups.com/forums/showthread.php?3139125-Il-Moar , but it doesn't really say much.
@@TonyMeggs bonjour a vous .très belle realisation. je serai très interressé pour réaliser cette belle aile. serait possible d'avoir plus de precisions..alainleboheme@ gmail.com merci a vous
Hey Dan! thanks for the comment. I never finished that plane, but this one is almost the same. The half-built aircraft is hanging up in my shed, part of the "Museum of Broken Dreams". cheers, hope you are well.
Hey i fly a sf-25c mofa too, just older than yours, but why do you turn off your engine when you want to land? I use to just let it idle, then i use the thermals to make some cheap flying, then if i need to gain hight if i couldnt find thermals i can start to warm up the engine slowly, i dont know how rules are on limbachs in your area regarding tbo? Here you can go over the tbo limit as long as the engine can pass compression test etc, and high throttle on cold engine is an engine killer. Plus you dont need to panik if you come short, if you come in to high like this video has you heard about side gliding? ( direct translated from danish ) you kick out your rudder to lets say right and then you adjust your speed by adjusting your decend rate, just be care because you need to listen out your speed from the air, your speed indicator cant be trusted when doing this, but i garantee you that you will come down very fast and you only practice in higher altitude until you are comfortable with it. The sf-25 has really bad brakes ;) a little tip: dont overspeed, i use an approach speed of about 100-110 depending on wind speed and the brakes works worse the faster you fly.. then there are three types of motorgliders ( under easa / dsvu ) type 1 is a glider with a engike you pull out and can get you home, nothing more nothing less, then there is type 2 which is a glider with a engine you can pull out and start with then pull back into the plane and it performs almost like regular glider, then there is type three which is the tmg - touring motor glider which is like a two seater motorplane with a better glide ratio, thats the sf-25. This is just a great plane to fly with, really forgiving.. great video. And safe flying to you.
good question- two reasons. One is to reinforce that we are glider pilots, and therefore practice every landing as a glide approach, and two- the prop clearance is very limited, so landing with engine running would very likely result in a prop strike. Having said that, obviously if you screw up and are going to land short you would re-start to avoid a landing/crashing short. Side-slipping is something i use routinely to lose height in gliders and ultralights.
Tony Meggs yes the sf-25 is famous for its low prop clearance. You really need to think about not tipping over, but its seldom on landings here, i usually land on a runway, but i get your point about shutting engine off, but here coming short is one of the popular way of crashing, especially with turbos ( type 1 and 2 motorgliders that retracts from body ) where people recognise they are to low and try to start this engine and often that makes stressfuld reactions resulting in a crash.
Every landing doesnt have to be an "adventure" if you just leave the engine on idle. This is the preferred method in a touring motor glider and is far better for the engine. To try and restart on base / finals if you encounter unexpected sink,when the cockpit workload is highest, doesnt make sense to me. Just an opinion.......
Took me about 2 years, but I can finally share a similar - albeit less educational - video. Thank you Tony, your video clip was a great inspiration for me :) ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-C8aaK1DXa1Q.html
Good video, Tony. Thank you for sharing. I'm a little puzzled that when you felt you had not enough height, and then contemplated a restart, that you still maintained a regular circuit and approach and did not turn in to the runway at an angle to compensate for what you perceived was a lack of sufficient height. My view is that an approach and glide started from overhead, following shutdown, would have been a better bet, less likely to lead to uncertainty.
Good Job! Thank you for sharing Tony. You give us food for thoughts with this great plane of yours. I wonder if i should pick up this unpowered landing habit with my 1:16 glide ratio?
Not very good for the engine, first it's warm, then you super-cool it, and then restart not very smart for the long term health of the engine and anyone who might purchase it in the future. You should retink that practice for the future.
