As an engineer and pilot (hang gliders and fixed-wing aircraft) This is great stuff for sure. I was the certification engineer on the Europa / Liberty XL2 and was tasked to witness the wingload test here in Florida many years ago. And guess what, that wing failed with less than half the anticipated load so a redesign was instituted with a follow-up retest and it passed thankfully.
So the experiment/test was a complete success. You needed to know the performance values, & to know if there was any weakness in material or design. While the cross tube failed under test, it provided the answer to one of the many tests that were performed, so, information gathered, lesson learned, improvements made & quality of design & materials used is now assured. The wing fail must be seen as a positive step forward & the experiment/test as a complete success.
Fantastic. I agree, letting us end-users get a peek behind the curtain is confidence inspiring. I have my finger's crossed that you snag a good slice of the Sub70 market. Just finished building my trike and adding one of your keel kits to a Fly17... Low and slow for now :)
Thanks Tim for sharing this stuff. Really interesting. I remember when I I bought an electraflyer cirrus 5 in 1977 they showed pictures of their test rig which was a truck with 55 gallon drums full of sand on the front and a similar rig. But this is going a long way and this is great. They tested nine g's positive seven g's negative. That's all I know. Otherwise my experience is limited.
When we were testing the Discovery , which has quite an aero elastic frame, we were unable to pull more than 3gs even when we were over 70mph airspeed. Given it was impossible to fly faster than 50mph it meant it was unbreakable in positive g.
Absolutely fascinating. I always wondered whether the saying "there's no substitute for real experience" was true with the development of computer simulation in aviation - but I reckon it's still true!
You can offset that load pressing up on the crosstube from the undersurface by moving the sidewire attachment a small distance inboard on the cross tube. I recall the Solar Wings Scandal had the wire attached about 100mm in from the end to achieve this.
Actually if you have a wing on there and you didn't think it would break and it broke while you were testing it you could jump out and kiss the Earth and saying oh happy days because anybody can miss and that's a good way to miss right there hook to a test rig on a truck with a camera on it instead of somewhere else where you were flying and nobody knows what happened to you.
Congratulations! It is quite nice to let us to see behind the curtain and to understand better your work and your achievements. The people seeing your serious approaches to the safety tests will definitely rise the trust in the Avian products! Good job! 😊
You need to fix the nitros and add 250kg of weight to the front bumper. We’ve pulled as much as 2300 lbs before the front end of the truck gets too light to steer.
I have to apologize but I don't have my audio working... that being said, I can tell you right now that truck will never get off the ground. Not the right lift to weight ratio. I'm not a Eng but I do play one of TV. Good luck and I Hope that helps. Cheers from So.Ca.USA 3rd House On the Left
I'm not sure it's history, but I think there were two identical ones made originally, one for the US and one for the UK associations in the 90s. This one got upgraded datalogging and electronics in probably the mid 00's, I think there was a PhD student from Cranfield University involved in that.
@@avianhanggliders1985 correct, looks like the one used for the TRX, TR3, iirc. just wrote about the TRX 160 positive load test. Mark's rig when he was living in Tehachapi, working at Boss film was a 5.7l extra cab C2500 with a performance chip, Wills Wing bought it shortly after, added 500# free weights stacked on the driver's side front corner. The California City airport runway wasn't long enough to get 72mph target speed at 25º root stall angle, the rig was out of nitrous or pre- NOS system install. Mark set pitch at 5º+, accelerated to around 75mph IAS and raised the pitch with the dial control. As the glider pitched up to around 10º the pitch force overwhelmed the landing gear worm drive motor and went to the stop at +35º. Both front wheels came off the ground for a moment. Mark instantly let off the gas, got 3 seconds of over target speed , 72mph to qualify a higher than 49mph VNE. As the truck came to a stop at the end of the runway Mark said, " never doing that again" the data recorder showed >2400# peak total force
The crosstubes are 62x0.9mm 7075-T6. We added an internal sleeve (60x0.9mm 7075-T6). Yes centred on where it broke, which was also the middle of the tube (as you'd expect for a slender beam in compression). From memory, I think it was about 1m long sleeve. The main purpose of the sleeve is to add bending stiffness to prevent buckling. A very short sleeve will increase the stiffness in a short area, so will only increase the buckling load a little and it will fail at the end of the sleeve. As you increase the length of the sleeve, you increase the buckling load and move the location of failure further out until you reach a point where it will go back to failing in the middle of the tube and increasing the length of the sleeve will have very little effect (other than adding weight). So we were aiming for just before that point.
We completely strip it down. Discard all the wires as a matter of course, inspect every other component individually and rebuild it. I might keep this one for my own use and to lend out as a demo wing.
Thanks, yes, we were really lucky to have the drone with someone else to fly it for the first day, that made very good footage. There's so many things to keep track of, making sure that the datalogging equipment is all set up right and recording that remembering to set up cameras and get them running takes a bit of a back seat.
It's a shame so much effort expended on a fundamentally flawed and limited design The rogallo derivative designs have been obsolete since the advent of the Volmer Jensen , the Swift, the Superfloater, the Archaeopteryx, etc. They could all accommodate a redesign to allow prone flight if desired, with much less drag, greater crashworthiness, safer landings, and greater aerodynamic maneuverability.
Firstly, modern flexwings trace their roots back to Rogallos, but they're now very different aircraft. Secondly, this particular video is about a wing for sub-70 trike use, not a free flight hang glider. For a sub-70 type microlight then flexwings make a lot of sense, they're light, packable, quick to rig, I notice your profile picture is one such wing. Thirdly, as your comment seems more about free flying hang gliders then what you're basically describing is an AIR Atos. These do exist and they are indeed great aircraft. Many people fly and enjoy them. Also the I believe the Swift and possibly the Archaeopteryx are still available and although they are also great aircraft they are of limited appeal due to high cost and low practicality. However flexwing hang gliders are also great aircraft, they're a long way from a Rogallo. Many more people enjoy flying flexwing hang gliders than rigid wings or the 3 axis foot launched types. This doesn't mean there's no room for improvement though, they're still a long way from optimal and borrowing concepts from both rigid wings and paragliding wings to improve the flexwing concept still further. I'll be releasing further videos on what we're doing to further develop this.
As an engineer and pilot (hang gliders and fixed-wing aircraft) This is great stuff for sure. I was the certification engineer on the Europa / Liberty XL2 and was tasked to witness the wingload test here in Florida many years ago. And guess what, that wing failed with less than half the anticipated load so a redesign was instituted with a follow-up retest and it passed thankfully.
So the experiment/test was a complete success. You needed to know the performance values, & to know if there was any weakness in material or design.
While the cross tube failed under test, it provided the answer to one of the many tests that were performed, so, information gathered, lesson learned, improvements made & quality of design & materials used is now assured.
The wing fail must be seen as a positive step forward & the experiment/test as a complete success.
Fantastic.
I agree, letting us end-users get a peek behind the curtain is confidence inspiring.
I have my finger's crossed that you snag a good slice of the Sub70 market.
Just finished building my trike and adding one of your keel kits to a Fly17... Low and slow for now :)
Thanks Tim for sharing this stuff. Really interesting. I remember when I I bought an electraflyer cirrus 5 in 1977 they showed pictures of their test rig which was a truck with 55 gallon drums full of sand on the front and a similar rig. But this is going a long way and this is great. They tested nine g's positive seven g's negative. That's all I know. Otherwise my experience is limited.
Wow, blast to the past, I had a Cirrus 3 and then a 5, those were the days.
Thanks for doing what I always thought of !!
When we were testing the Discovery , which has quite an aero elastic frame, we were unable to pull more than 3gs even when we were over 70mph airspeed. Given it was impossible to fly faster than 50mph it meant it was unbreakable in positive g.
Very educational. Awesome
Tim I wish you health and strength to achieve your goals.
love me a good old fashioned "mobile wind tunnel".. .. very cool test rig!
Absolutely fascinating. I always wondered whether the saying "there's no substitute for real experience" was true with the development of computer simulation in aviation - but I reckon it's still true!
You can offset that load pressing up on the crosstube from the undersurface by moving the sidewire attachment a small distance inboard on the cross tube. I recall the Solar Wings Scandal had the wire attached about 100mm in from the end to achieve this.
Yes, that's true.
Actually if you have a wing on there and you didn't think it would break and it broke while you were testing it you could jump out and kiss the Earth and saying oh happy days because anybody can miss and that's a good way to miss right there hook to a test rig on a truck with a camera on it instead of somewhere else where you were flying and nobody knows what happened to you.
That's how Flattersturz accidents were investigated by Michael Schönherr in the 70ies.
Super interesting vid Tim (although my unscientific mind didn't always keep up). Super stuff man !
Glad you enjoyed it!
Congratulations! It is quite nice to let us to see behind the curtain and to understand better your work and your achievements. The people seeing your serious approaches to the safety tests will definitely rise the trust in the Avian products! Good job! 😊
Brilliant!
You need to fix the nitros and add 250kg of weight to the front bumper. We’ve pulled as much as 2300 lbs before the front end of the truck gets too light to steer.
Good Work Avain ❤
Interesting viewing thanks
Reassuring thanks.
Your looking happy and healthy Tim 😊😊
Thank you.
is it more annoying to test or to die? a little annoying is always better than death. imho keep testing!
thanks for sharing
What would you do if the hang glider picked the pickup truck up rather than failing. Other than be happy...
Would you put on the parking brake?
The front of the truck does get pretty light on the high load runs. There have been cases of the test rig doing a wheelie! Pretty scary.
and what did it sound like inside the test truck when that cross tube exploded?!?!
A big bang! (although not quite as bad as I had imagined it might be, and the truck didn't wobble much).
How many lbs is the truck? Will the truck have normal avionics display? What will be the Chevys max altitude and cruising airspeed?
I have to apologize but I don't have my audio working... that being said, I can tell you right now that truck will never get off the ground. Not the right lift to weight ratio. I'm not a Eng but I do play one of TV. Good luck and I Hope that helps. Cheers from So.Ca.USA 3rd House On the Left
🤣🤣🤣
Great stuff👍
When's it going to be available?
Cheers
Now!! www.avianonline.co.uk/riot-p-2003.html
curious where the test truck came from, if it is one of Mark West's designs.
I'm not sure it's history, but I think there were two identical ones made originally, one for the US and one for the UK associations in the 90s. This one got upgraded datalogging and electronics in probably the mid 00's, I think there was a PhD student from Cranfield University involved in that.
@@avianhanggliders1985 correct, looks like the one used for the TRX, TR3, iirc. just wrote about the TRX 160 positive load test. Mark's rig when he was living in Tehachapi, working at Boss film was a 5.7l extra cab C2500 with a performance chip, Wills Wing bought it shortly after, added 500# free weights stacked on the driver's side front corner. The California City airport runway wasn't long enough to get 72mph target speed at 25º root stall angle, the rig was out of nitrous or pre- NOS system install. Mark set pitch at 5º+, accelerated to around 75mph IAS and raised the pitch with the dial control. As the glider pitched up to around 10º the pitch force overwhelmed the landing gear worm drive motor and went to the stop at +35º. Both front wheels came off the ground for a moment. Mark instantly let off the gas, got 3 seconds of over target speed , 72mph to qualify a higher than 49mph VNE. As the truck came to a stop at the end of the runway Mark said, " never doing that again" the data recorder showed >2400# peak total force
and how big of a sleeve did you add to the cross bars? an inside or outside sleeve? and centred on where it broke?
The crosstubes are 62x0.9mm 7075-T6. We added an internal sleeve (60x0.9mm 7075-T6). Yes centred on where it broke, which was also the middle of the tube (as you'd expect for a slender beam in compression). From memory, I think it was about 1m long sleeve. The main purpose of the sleeve is to add bending stiffness to prevent buckling. A very short sleeve will increase the stiffness in a short area, so will only increase the buckling load a little and it will fail at the end of the sleeve. As you increase the length of the sleeve, you increase the buckling load and move the location of failure further out until you reach a point where it will go back to failing in the middle of the tube and increasing the length of the sleeve will have very little effect (other than adding weight). So we were aiming for just before that point.
would that glider that survived the testing be able to be sold/flown as 100%? Or do you not trust test gliders that have been pushed to the limit?
We completely strip it down. Discard all the wires as a matter of course, inspect every other component individually and rebuild it. I might keep this one for my own use and to lend out as a demo wing.
It's a shame the later footage wasn't as good as the first test, but I really enjoyed this video, even though some of it went over my head
Thanks, yes, we were really lucky to have the drone with someone else to fly it for the first day, that made very good footage. There's so many things to keep track of, making sure that the datalogging equipment is all set up right and recording that remembering to set up cameras and get them running takes a bit of a back seat.
@@avianhanggliders1985 for sure, I'm currently doing EP training and not allowed to use a go pro as my instructor says it's too much of a distraction
🎓 ..................✏................. 🎓
Bravo sauf que !
Nord mal ment : l'essai se fera sans pivotement afin de valoriser.... this Flex resist
It's a shame so much effort expended on a fundamentally flawed and limited design
The rogallo derivative designs have been obsolete since the advent of the Volmer Jensen , the Swift, the Superfloater, the Archaeopteryx, etc.
They could all accommodate a redesign to allow prone flight if desired, with much less drag, greater crashworthiness, safer landings, and greater aerodynamic maneuverability.
Firstly, modern flexwings trace their roots back to Rogallos, but they're now very different aircraft. Secondly, this particular video is about a wing for sub-70 trike use, not a free flight hang glider. For a sub-70 type microlight then flexwings make a lot of sense, they're light, packable, quick to rig, I notice your profile picture is one such wing. Thirdly, as your comment seems more about free flying hang gliders then what you're basically describing is an AIR Atos. These do exist and they are indeed great aircraft. Many people fly and enjoy them. Also the I believe the Swift and possibly the Archaeopteryx are still available and although they are also great aircraft they are of limited appeal due to high cost and low practicality. However flexwing hang gliders are also great aircraft, they're a long way from a Rogallo. Many more people enjoy flying flexwing hang gliders than rigid wings or the 3 axis foot launched types. This doesn't mean there's no room for improvement though, they're still a long way from optimal and borrowing concepts from both rigid wings and paragliding wings to improve the flexwing concept still further. I'll be releasing further videos on what we're doing to further develop this.