• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

J&H Aerospace Spinster 1.5m DLG from foamboard

FAI-F1D

Free Flight Indoorist
#1
Inspired by Flyboa's successes, I drew up a foamboard DLG earlier this week, but with a few upgrades from his airplanes. What I wanted was a full house DLG requiring only a nontapered carbon tube boom, sheathed nose, and removable wing.

And that resulted in this set of plans:
Spinster.png

Two evenings of building resulted in this rascal.
IMG_20170413_224823370.jpg

I took it to work today and headed outside once the grass dried off...
IMG_20170414_100822843.jpg

It took two test glides to get the elevator trim where I wanted it. Everything else was fine. First full turn launch put it about 30ft up for a nice floating glide of about 20 seconds.
IMG_20170414_095748082.jpg

After that I gradually increased the power until I was giving it almost full power launches and getting it well over 50 ft up. And there was lift, and more lift , and even more. Other than one land-out, I was able to bring it back everytime, even from deep downwind.

Handling was very nice. No tip stalling or any nonsense. My only complaint is it could use a tad more elevator authority and maybe a little more roll response. A beginner wouldn't notice the difference--I'm spoiled by composite DLGs.

And then I hit the big one and got it way up there for a nice 5 minute flight.
IMG_20170414_100311674.jpg

IMG_20170414_100313352.jpg

I'll write up an article detailing it soon enough and hopefully will get some flight video later. This has turned out to be a good airplane, and I suspect we'll be seeing more of them soon. Perhaps a gaggle at Flite Fest?
 
Last edited:

rockyboy

Skill Collector
Mentor
#6
Awesome! Thanks for sharing plans and article on this - one of these days I'm going to dip my toe in the DLG water, and DTFB seems like the ideal way to try.
 

AkimboGlueGuns

Biplane Guy
Mentor
#7
Yep. Yep. Yep. Yep

I'm going to build one of these ASAP. My Whippit is starting to hurt more throwing arm. Can't wait to fly a full size DLG again.
 
#9
More specifics on carbon tube?

Hi Joshua -

Do you have any more specific advice on the carbon boom? Recommended outer/inner diameter, or total weight? You say "at least" 32 inches, do you have an optimal length in mind for the design? How does the design/build-process accommodate having a different length spar? I assume there are both balance/CG issues as well as tuning of the rudder/elevator throws given a shorter/longer spar...

E.g. looks like the stock straight wrapped-carbon tube at Goodwinds would be 0.375" (I.D.) at 48", around 1.6oz at that length (and over $28 in single quantity, plus shipping?). Would a smaller diameter of the "Sky Shark" P-series tube there be appropriate as well (most in 32.5" lengths, though you could get 42" and cut down)? Or is there a reasonable option from CST, to cut down the number of distinct orders required? (Maybe their "DPP Ultra Light Carbon Tube" 8.0 mm OD, 7.0 mm ID, 1m length, 18.1 grams @$11.50 each.)

Meanwhile on Amazon most of the carbon-tube items are 500mm and the arrow shafts seem to be 31" or shorter and lesser diameters as well, so those don't look like viable alternatives.

(Cross-post to FT Forums and JHAerospace.com - answer where you feel it will do the most good?)

Thanks!
Adam
 
#10
#11
Thanks Flyboa for the input. Note that the Sky Shark "PT" tubes are tapered (as opposed to the straight/constant-diameter "P" series tubes). By the description on Sky Shark's web site, the tapered tubes will be stiffer but not as durable as a straight tube of similar weight and same length.

Also of interest, the site you reference (kitesandfunthings) has similar description and size chart for the Sky Shark tubes to the Goodwinds site referenced by Joshua, but some of the sizing details are different for the same tubes? Also the prices are very different. Even worse, I found the apparent source manufacturer at SkySharkTubes.com, and their web page values for the P tubes vary from their own PDF. Kitesandfunthings seems to match the PDF values, while Goodwinds has variance from those for the P-300 and 2P sizes, and also gives weights in ounces which don't match the (converted) values in grams from Sky Shark.

So while it probably doesn't matter to me at the scale of this project, it's a bit tough to tell what's going on (and whether one of the sites has made an error, or is playing funny games...). Anyone gone further down this rabbit hole already?
 

FAI-F1D

Free Flight Indoorist
#12
I recommend a 7-8 mm tube, 0.5-.075mm wall thickness. 32" carbon arrows with 7.6mm shafts will work fine for this, and the production model will used these.

Speaking of which, I'll be offering receiver-ready Spinsters for $75 each at Flite Fest.
 

AkimboGlueGuns

Biplane Guy
Mentor
#15
Hey Joshua. I might try making a 3d printed sheath to replace the foam/paper one on the plans. Let me know if you want the files once they're done. I don't think it's going to be too hard to model, but I won't be able to test print for a little while because our printer nuked itself last night. Need's a new board, which will be here in a few weeks by my best estimate.
 

rockyboy

Skill Collector
Mentor
#16
I recommend a 7-8 mm tube, 0.5-.075mm wall thickness. 32" carbon arrows with 7.6mm shafts will work fine for this, and the production model will used these.

Speaking of which, I'll be offering receiver-ready Spinsters for $75 each at Flite Fest.
Take my money! How about a pre-order?
 

FAI-F1D

Free Flight Indoorist
#17
Hey Joshua. I might try making a 3d printed sheath to replace the foam/paper one on the plans. Let me know if you want the files once they're done. I don't think it's going to be too hard to model, but I won't be able to test print for a little while because our printer nuked itself last night. Need's a new board, which will be here in a few weeks by my best estimate.
I could see doing that to replace the foam nose cone, but doing the whole sheath that way is going to add a bunch of nose weight you don't need (or want, given that I went for the minimum vertical stab area necessary to resist the rotational inertia at launch). The tails are pretty light on this design, so you'd need to add lead to the tail (increases the rotational inertia even more).

Not trying to be a wet blanket, just full disclosure that we're operating on the razor's edge here. Part of the high performance of this model is going to a lower than normal wing loading.

If you can get it to work with 3-D printed components, please post your progress. This is a completely unexplored segment of aviation so I honestly have no idea where this project will end up or what will end up working, especially given that I really had very low expectations for this model when I built it. And then last weekend I found myself hunting thermals with it in strong winds.

Take my money! How about a pre-order?
Sure! I take paypal. ;)
 

AkimboGlueGuns

Biplane Guy
Mentor
#18
could see doing that to replace the foam nose cone, but doing the whole sheath that way is going to add a bunch of nose weight you don't need (or want, given that I went for the minimum vertical stab area necessary to resist the rotational inertia at launch). The tails are pretty light on this design, so you'd need to add lead to the tail (increases the rotational inertia even more).

Not trying to be a wet blanket, just full disclosure that we're operating on the razor's edge here. Part of the high performance of this model is going to a lower than normal wing loading.
Valid points. I think I can get the thing printed pretty light if I try doing it with thin (maybe one or two print layers) walls. I built 3DLP's Edge 540 and I was really surprised at how light the airframe was. For that big hunk of plastic my hand scale says about 1 KG for ~4' span. I think around 10-15 grams is realistic for the whole piece considering the small size and simple shape.