What's new
By:
Aloft Forums

Welcome to Aloft Forums. Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!

Polyhedral DLG

Development is just so damn cool.

I was taught by my Prof at Cambridge that ALL results are good.
If you succeed, you can continue down that path - or the success may even lead to other roads.
If you fail, then you know what NOT to do next time - something has been eliminated from the equation so it becomes simpler.

Or as the Japanese say: No try = no result.

Me? I'm still living and learning and hopefully always will be.

Doc.
 
I have made some more moulds in CAD to do two things.

(1) improve the fuse moulding quality by using outer male moulds over all sections.
(2) to allow me to try moulding directly into the outer moulds using a ballon to compress the carbon fibre.

I will do some more trials next week - the first version from this week is not too bad, and is nice and stiff, bu I wonder if I can make the boom lighter given the braided CF sleeve are 3k (quite heavy) - I will try and roll some of my carbon cloth as an experiment!

Screen Shot 2021-05-21 at 12.40.37 PM.png
 
Yesterday was better weather, but I was busy on other things so today had to do - the wind was a light south easterly but was forecast to increase during the day.

I am still a novice when it comes to these ships and I have a habit of bringing them home in pieces - today I wanted to be a bit more cautious! I am in the process of building some DLG parts and that is another story in itself, but in the meantime I need something to keep me in business - I purchased a 2nd hand BAMF fuse which has been thoroughly worked over and has also been extended 3cm in the boom - I have been tickling away for a bit putting it together while in tandem refining my Open TX DLG program to fly it - a week or so ago I also added a momentary switch behind the left grip for the launch mode.

Well, it flies, but it is twitchy as hell - I think it is largely the lengthened boom - my CG is the same as the previous fuse setup, but I am not sure if the incidence is the same - I seem to need a bit more up elevator to fly hands free.

After a couple of flights I found the vertical stabiliser was loose so I went home and added some epoxy - back to the field the wind had notched up a bit more (I probably should have gone home), but I was determined to persevere! I tickled with the ailerons and elevator and got a few good throws in, but it was too windy to really assess the trim.

What I did enjoy was using the launch mode on the momentary button! Awesome!

Glad to report we came home in one piece!


Screen Shot 2021-05-23 at 5.29.28 PM.png
 
Last edited:
bracesport said:
Yesterday was better weather, but I was busy on other things so today had to do - the wind was a light south easterly but was forecast to increase during the day.

I am still a novice when it comes to these ships and I have a habit of bringing them home in pieces - today I wanted to be a bit more cautious! I am in the process of building some DLG parts and that is another story in itself, but in the meantime I need something to keep me in business - I purchased a 2nd hand BAMF fuse which has been thoroughly worked over and has also been extended 3cm in the boom - I have been tickling away for a bit putting it together while in tandem refining my Open TX DLG program to fly it - a week or so ago I also added a momentary switch behind the left grip for the launch mode.

Well, it flies, but it is twitchy as hell - I think it is largely the lengthened boom - my CG is the same as the previous fuse setup, but I am not sure if the incidence is the same - I seem to need a bit more up elevator to fly hands free.

After a couple of flights I found the vertical stabiliser was loose so I went home and added some epoxy - back to the field the wind had notched up a bit more (I probably should have gone home), but I was determined to persevere! I tickled with the ailerons and elevator and got a few good throws in, but it was too windy to really assess the trim.

What I did enjoy was using the launch mode on the momentary button! Awesome!

Glad to report we came home in one piece!


View attachment 7052
Click to expand...
Keep rolling Phil.

When you made the longer tail did you reduce the elevator movements? A longer tail with smaller moments should give you more precise and smoother control. You mentioned incidence? Don't know what the wing section is, but unless its severely undercambered, you probably wouldn't need any incidence. That could explain the pitch control jitters if they were still there after you secured the loose tailplane.

On a new model I think you'll only get a really good idea what happening if you fly it as often as possible. I know F3k models don't fly on the slope but its often a good place to get the general model trimming and adjustments done, as you can fly longer without going home with your arm in a sling!

I think you are doing really well.

Doc.
 
Thanks James, yes, I dialled down the elevator rates towards the end, but the wind was a bit to aggressive to really know what was going on! This second hand fuse came from a pro flier, so it should be pretty good for setup - I think maybe I need to look at the CG a bit more closely on a calm day - I might try the slope test too!
 
Ok, so if making your own Sine wave molds have you thought of making them with the amplitude progressively dropping towards the tip. This will reduce the weight out at the tip. As the tortional loads are less at the tips there isn't so much need for as much back and forth action
 
Last edited:
Konrad said:
Ok, so if making your own Sine wave molds have you thought od make them with the amplitude progressively dropping towards the tip. This will reduce the weight out at the tip. As the tortional loads are less at the tips there isn't so much need for as much back and forth action
Click to expand...
I think if you increase the frequency Konrad, you are putting more material at the tips - not less. Also as you say you don't need so much torsion resistance out there, plus the height of the spar is reducing. Thats why the constant wave frequency works so well.

Its not quite what it seems at first glance.

Cheers,

Doc.
 
@gp49 - this is my second go at James SWS spar - the first being on my pitcheron wing shown below.

The DLG wing is so dinky so I made my SWS template dinky too - it is all a bit of an experiment! James has hollow wings and so he builds the spar as a complete thing (I think), whereas I build mine into the foam and then cap it with the skins - seems to work...

313621_2fc9d2c6596f57bb6b45a2682cc4a5a1.jpg
313641_76b4311c57c0ffc7974e18daa3744f1f.jpg
313644_537de58d049a52f48e5416c786759ede.jpg
 
Agreed more frequency more material. I'm advocating that the amplitude drop (less) motion going from the LE to the TE as we move towards the tip. Bringing the web out at the tips to look more like a straight web of a classic I beam.

I would also stretch (lower) the frequency making fewer bumps out at the tips.
 
Last edited:
in my case I have a polyhedral too - so I am planning (for ease) one template for the SWS and varying the wall thickness of the inner panel vs the outer panel - it is all a bit of an experiment!
 
A beautiful autumn day deserves a lunchtime flight - it was dead calm and the flying was great, I felt like it was my best effort to date - I should have been concentrating on trimming as it is not spot on yet, but I was having fun and it was launching very well - until the end!


Screen Shot 2021-05-27 at 8.57.31 AM.png
 
Seems the BAMF nose was broken and poorly repaired before I acquired it - another reason to keep building! On a brighter note, I completed the moulds for the new fuse - hers e are the nose cover moulds - they are looking good! :)

IMG_2281.JPG
IMG_2282.JPG
IMG_2283.JPG
 
Konrad said:
Agreed more frequency more material. I'm advocating that the amplitude drop (less) motion going from the LE to the TE as we move towards the tip. Bringing the web to look more like a straight web of a classic I beam.

I would stretch (lower) the frequency making fewer bumps.
Click to expand...
Hi Konrad - Gotcha. I keep the amplitude as I am a lazy bugger, but I reduce the carbon spar and spar cap plys towards the tips.

For home builds its open season.

Cheers,

Doc.
 
You must log in or register to reply here.

Similar threads

Compositall
Repair Kit "Carbon+" for Repairing DLG, HLG Models, and Small Composite RC Models
Replies
5
Views
3K
gp49
gp49
Back
Top