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By bobknop
#400409
I more or less calculate the grossweight [Wing powerharnas and pilotweight together) on examples I see on utube etc.
I guess ten kg/twentyfive lbs overweights sometimes.
My question: how much risk is involved exept stall speed and landingspeed increase.
In other words: when is over top grossweight a risk for structural failure? Is limiting yourself to low g manoeuvring
to ,say two to two and half G enough?
Regards Bob.
By HG-Pilot
#400419
Hi Bob, I fly a sting 154 2 xc which has a 90kg max hook in weight yet I weigh about 105kg with the powered harness. I have not noticed any increase in stall speed (although it will increase naturally) and is still easy to land. I can also still take off nill wind which tells you somthing. On my glider the hook in weight is 60-90kg optimal hook in weight. I am not to worried as I think it is mainly refering to the best weight range for the optimal performance of the glider and not so much the strength of the glider. As far as I know it has all the same aluminum size, side wire size, and sail type as the 175 xc which has a 130kg max optimal pilot weight range. Even though there will be a minor amount more pressure on the sail I cant imagine its a strength issue. Also we generally fly powered harness when the weather is calm with no thermals or bumps etc. Check out some of my vids on youtube if you like my chanel is HG pilot.
Regards,
Nathan
By bobknop
#400442
Thanks,I needed a bit of reassurance,I like your train spotting video.

One more question, does anyone have info about design limits for Hg?
What I would like to know is how many G positive and how many G negative
A hangglider can take for an average kingposted glider before it fails.
Regards Bob.
By HG-Pilot
#400450
Thanks Bob, I should have mentioned that there are only a few vids I have of the glider in question.
Dont quote me on this but here in Australia our gliders (moyes and airborne) are tested to something like 6g positive and 3g negative as a minimum.
User avatar
By lizzard
#400660
I wonder when the manufacturers will take advantage of rc technology and do real flight tests ?
Gather real data?
As always there is always a pilot willing to do that stuff for free!

Elephant in room watching naked emperor?

It would be most revealing but for now sand bags and runway pickups will fill us with confidence .

This may have been done ..if so please deignorize me .
User avatar
By Paul H
#400664
lizzard wrote:
Sat Oct 14, 2017 7:08 pm
I wonder when the manufacturers will take advantage of rc technology and do real flight tests ?
Gather real data?
As always there is always a pilot willing to do that stuff for free!
Why would you think that truck mounted dynamic testing isn't "real" testing? The parameters can all be controlled without having to deal with the inaccurate inputs of a pilot.
User avatar
By lizzard
#400666
I suppose its all the high g failures we now see on so many videos .
The truck test does not negate the validity for a another method which is available .
knowing the weak points in real flight would be useful for some and the videos of that would be watched by many ,
there are no negatives, just a challenge to implement.
In accurate pilot inputs is what this is about on one level..we have all pushed the limits at different times and this will continue unless my understanding of the challenge to fly and getting high and sick with adrenaline was only me in my younger days .....which still grabs me .i just need less g now ..more about nailing cliff landings and precision these days .
User avatar
By lizzard
#400668
This may also be a step toward solid suspensions and negative g control ?
Imagine not having to worry about a tumble .
Drone technology will adapt here and very accurate scenarios could be created
All good for wing /harness evolution .
Perhaps better than a truck?
By bobknop
#400669
Truck mounted dynamic testing ,does anyone have a link to their test protocol?I would like to know
how many G positive they load the glider in the test.
Do they go on to complete failure of the wing?
By HG-Pilot
#400674
There was a video somewhere on the net of airborne truck testing a REV and I think they mentioned the G forces etc. I cant seem to find the video anymore. But still I think the requirements are 6 g positive and 3 g negative as a minimum but could be wrong. What I do know is that well maintained gliders dont break.
User avatar
By lizzard
#400675
Back about 20 years ago I had an xs 155 that i wanted for a light trike . I did all the right things with the keel,wires etc, but i noticed that at full vg on the ground the xbars had a bend in them which was proportional the the mount of vg .
It had a ball joint(one of the first ) and 57 or 60mm xbars. Which i thought to be an improvement but the bending ? It worried me so i contacted moyes and was told that they were aware of ot but all certifications were passed so don't worry.
But they were not made for trikes . All good advice ..The cause was the leading edge x bar junction which had off set for easy pack up .
I ordered airborne parts for that section e xbar leading edge junctions (straight ones )and no more bend. to be fair they probably did pass certification but who wants xbars that are bending under load .

My own flight testing verified that they did not fail as i greyed out .

The older method was to have bends at both the leading edge and opposite at the xbar centers which was not ideal but better than having a set bend .(compressing the tube from opposite sides )..evolution continues and I too am concerned that it's a tickybox mentality .(which is what compliance is )..but not knocking it just suggesting that improvements are always available especially now we have plug and play flight systems that are as big as a match head ..
By bobknop
#400680
Hi Lizzard.
I looked up the max pilot weight for this xs 155, it says 109 kg.
Do you remember what your total hookin weight inc trike was?
I ask this because I am slightly overweight on my glider with a powerharns,
and try to determine whats acceptable.
User avatar
By lizzard
#400687
weights are given for ideal handling character in the first instance .
but if you are hanging too far forward ...is there keel strength there ?
look at the a frame /keel fulcrum ...
but on a nice say you be the judge .
do you want to throw it about and thermal ?
Have respect for the design weights ..for the guidance of wise men and for the protection of fools .
more info on your glider will get responses from those with direct experience .

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