Hi Stuart,

Well just watching this thing move is fun and worth a few views alone just to see it swing. I did say I might like to build one of these ... or something like it and well yeah there are a few tentative sketches but nothing concrete. In reading that it flies as well is quite interesting and yeah a video would be really good. But ok that will come in time I am sure. Again my hat is off and respect Stuart !! this is quite a piece of work.

Jens

I'll be in my bunk!

Originally Posted by g_munu

I'll be in my bunk!

"War Stories", my personal 2nd favorite.

Well yesterday was an unmitigated disaster.We found a good field,but the wind was too strong.Waited a bit,and in what seemed like a calm spell tried a throw into the wind.Of course a gust caught it,straight back over my head and a crunched wingtip resulted.
The wing is definitely fluttering,so I'm going to try some layers of packaging tape.
The blind nuts are only into balsa on the underside,I'll reinforce these as well.The outer one on the damaged wing has pulled into the wood.
Then rebalance and wait for a calm day.
Stuart

Kent,same drive,must be the reduced load.
I think I can make something resembling your sketch for the nuut,I'll give it a try
A sketch for the pivot points-probably later today

Mark,some of those co wings look ok(to my untutored eye).Some thing pretty docile to begin with,if we use a foam wing it will be easy enough to try more adventurous types later.
Serenity- hmmm
Stuart.

Originally Posted by Stupot46

Well yesterday was an unmitigated disaster.

It's never a disaster when you learn something. Here in my neighborhood, we call a wingtip like that a "bump". Looks to be still flyable.

Sorry, I'm not keeping up. Is this still a chuck glider??? That is no RC.

Kent

Originally Posted by Knoll53

Sorry, I'm not keeping up. Is this still a chuck glider??? That is no RC.

Kent

Still and always will be.Everything on the wing is 2mm.I thought that wrapping the balsa round the l/e and two carbon spars would be enough.I'll have a read up on the best way to use tape and see what that will do.A bit more weight won't hurt any way.
Stuart

Bummer Stuart sorry to see the mishap but it looks like a minor bit damage so no worries and glue it back together.

Jens

Thanks Jens.the repair is easy,stopping the wing flexing not so.I wish Ellie had filmed it,but with it popping back over me she missed every thing.Flutter gets mentioned a lot on these pages,but I can honestly say that is the first time I've seen it so pronounced.Tape first,then maybe double up the forward carbon rod if that doesn't work.
Stuart

Stuart - most of these flutter because of flexibility in bending at the root connection. You may need only to stiffen the rotational structure. Stiffening the wing panel alone may not help. Check to see if there is a lack of stiffness in that inboard area first.

While were on the subject of inboard and outboard, there is something that has been bothering me for a few days now. I keep hearing that the pivot point should be further out on the wing, right? But I am also observing the plethora of compound swept wings all over this forum. Just look at the dozens of threads here with those type.... Oh wait, there aren't any.(or maybe 1 with the tip section swept back a bit extra?) My point being that I think that the variable sweep wing out further from the center has a lot more to do with tailed, supersonic jets than it does with low RE model flying wings. Should we not maybe be thinking more about the strength and movement of the wing and just try to keep in line with Stuarts chuck glider as a design starting point? Sure, there needs to be a bit larger fuse to accommodate the mechanical bits and all - but trying to move the variable sweep point out further? What do you all think?

Mark

Thanks Herks,insightful as ever! The base plate is only balsa,which is not holding the captive nuts on the four through bolts.I plan a ply reinforcement here,weight should still be ok.
Everything I've built in the past has been from kits or plans,so this little item is the first thing I've put together myself.
At least I know it's capable of flight,I just need to get it strong enough.
Regards Stuart.

Oops

Mark,I think it was yours truly who raised this after reading up on swing wings.The reason NASA stated was to lessen the % of wing moved and so reduce the effective cog shift.The relative length of our wing will probably make any gain negligible.
Stuart

A question for our cad designers.First a disclaimer in case what follows is nonsense.I have no idea what your programmes are capable of.
Would it be possible to lay out a planform of a swing wing,and move the wings through the full sweep?I'm thinking if so by taking measurements at points along the sweep we can calculate exactly what the cog is doing.
If the wing movement will to some extent self correct the balance,could this and(Kents?)idea of weight in the wing be be sufficient?
The rough and ready three position measurements I took from the chuck glider would suggest that a weight could be tuned to move the same distance as the cog to balance the wing.The only drawback with the wing weighting is that it would move in an arc.
The above was prompted by the fact that the belt and pulley drive could have been used to move a weight,not so the latest version.
We will need to determine if cog shift needs to be built into the drive- this could be done using the linear belt drive I sketched out in a earlier post,the underside of the belt moving the weight.
Stuart