Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

SWR wing loading question..

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Old 11-24-2015, 11:10 AM
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MJD
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Default SWR wing loading question..

All you millions of people who build SWR's.. well actually I bet CP has built almost exactly this already.

I have a 24" span SWR delta wing sitting around that either has to become an airplane soon or it will fossilize, then be too heavy for anything. Eons ago it was to be a 1cc delta sort of fast trainer for small models. It gathered dust instead.

If I build it into a SWR delta, with upright engine (.15), fuselage pod below for small tank and generally minimalist - I think I can get final weight to about 24 ounces. The wing area is 1.58 sq ft. That gives about 15.2 oz/sq ft wing loading.

I'm not sure what to think about that wing loading, on a 24" span delta with flat airfoil. Might be fine, might be a bey-atch. Any thoughts?
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Old 11-24-2015, 12:57 PM
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Could also do 1.5cc .09 size .10 size see how it lands and go from there.
If you have nice green thick fluffy grass field the .15 should be bearable
during landings as long as the balsa has been holding up. Got a pic?
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Old 11-24-2015, 01:53 PM
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A year or so ago, I built 2 or 3 small deltas for E-power. They were flat wings made from Depron with LE and TE sheeting and capstrips of balsa, then covered with Ultracote. Wing loading was in the ballpark you describe. Launch was OK most of the time if I threw it hard enough. Power off, the glide was about the same as my car keys. The last one refused to launch, torquing into the ground no matter what I did. That was where I gave up on the concept. Too heavy.
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Old 11-24-2015, 06:25 PM
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I was thinking of an MDS .15 F2A speed motor. Static thrust will be sucky.

PS it is just the wing so far, I was all hot to make a little sport .15 delta in about 2009 or so as I recall, but went on to other things. This would be a 1/16" ply fuse, wing on top.

It would take me all of an hour and eleven minutes to make a new wing. Or just take the .25 Demon proto down to 23-24" and do it proper like with an airfoil. Maybe I should just build a better wing and do something else with this - not worth making big plans around $4 of 1/4" balsa!
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Old 11-24-2015, 06:45 PM
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My little flat deltas made me REALLY appreciate airfoils!
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Old 11-24-2015, 09:52 PM
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Yeah, I have always vacillated on whether it was fundamentally a dumb idea or not. I know sheet balsa deltas fly great when they are made light enough not to worry about wing loading.

Off to the Bat CAD.. take one proven 26" rc delta design, scale it down a hair and juggle as required.
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Old 11-24-2015, 10:06 PM
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Oh well, it was fun to imagine..

I'll work the speed top, or some of it, into the eventual design.

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Old 11-24-2015, 11:30 PM
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I have something comparable here to look at.
I don't remember the history but it looks like it was originally built for a Fora .049.
At some point it had a .15 engine mount grafted onto it.
I DO recall using a OS.15, 6.5 x 5, bladder, big venturi and open exhaust.
As it sits here ARF with a 270 NICAD, a pair of servos and just needing an engine and a RX it weighs 15 ozs.
If you add a stripped down .15..what's that, another 6 ozs or so...?
So, 22 inches of span, 18 inches long, possibly 22 ozs RTF and it ended up being a decent flyer after a few failed launches. It was twitchy in roll to the point of just needing 1/16" of aileron either side of zero. Pitch control and glide were OK, but yes it did resemble car keys . I even had the onboard pitot tube speed sensor in this thing and seem to remember 130 mph from the CVA, but I won't swear to that..
Is going this small and heavy worth trying...? It is if you are a little bit adventurous and don't care too much about the outcome.
26 inches of span would make setting it up less critical and it would still be plenty fast.
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Old 11-25-2015, 06:51 AM
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Which is exactly the span of the .25 Demon.. yeah I think this might be a PITA waiting to happen!
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Old 11-25-2015, 08:28 AM
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Yeechhh....looks like severe mold, dust, legionairre's disease.
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Old 11-25-2015, 09:22 AM
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I think it's volcanic ash. It's only a 4 hour drive to Mt St Helens.
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Old 11-25-2015, 02:14 PM
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Here is another Sterling Example of the breed.
This one is pretty close in shape and size to the plane you posted MJD.
It flew like it was top heavy with the high thrust line and all of the side area well above the wing.
Not a SWR, but basically a flat, 3/8" thick, open frame work that tapers to the TE flaps.
I posted this one to U-toob back when ProBroJoe first got me doing the Helmet Cam.
Not a terribly, awfully bad flyer [it never crashed]...but for some reason I only flew it a couple times before decommissioning it.
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Old 11-25-2015, 03:59 PM
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CP I think that is the delta you talked to me about when I first drew up the low wing version of the model that was to use that stupid 1/4" wing. When was that.. 2009, 2008.. LOL.

I recall you said it felt tippy, so I ditched the low wing idea, and I think shortly after that forgot about it and moved along to some other distraction. I think it would be wise for me to bolt the engine to something with better manners to start with.
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Old 11-25-2015, 04:33 PM
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Yep, it would be smart to build a "High Winger" if you want an easy to launch delta with plenty of room for your equipment and a nice grip for powerful launches.
Back to Flat Plate airfoils, I think there is an invisible line with respect to wing loading that makes them act like Bucking Broncos when the weight limit is exceeded. I've built a couple flat deltas with 3/8" x 3/8" balsa sticks, plenty of wing area and kept them light with .049 power. They fly smooth as silk.
OTOH, I've built light wing loaded, rectangular shaped, flat airfoiled PBFs that act like Bucking Broncos at anything above jogging speed.
Mysterious.
This one would accommodate a .15 pretty easily if you gave it a nose job.
It's roughly an 18 x 24 delta.
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Old 11-26-2015, 09:45 AM
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Considering how long it does not take to build one, and I get them cheap, I think I'll just scale the 26-3/8" Demon .25 down to 24", that gives a reduction of about 80% in area to about 275 sq in, and will hold a 3-4 ounce tank without much trouble. It should make an okay test bed for this engine in an RC application.
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Old 11-26-2015, 04:46 PM
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I really think that having a low CG helps give these 24 inch span planes an extra margin of stability...especially if you want to GO BIG & HEAVY with a .15.
Having the built in hand grip for launches is nice, too.
You could sink the firewall a little bit and form a belly to lower the fuel tank, giving your pipe more room.
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Old 11-27-2015, 08:07 PM
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Our DSL internet stinks - noise noise noise bla bla - there are 2km of lines with twists, moisture, naked mole rats and Lord knows what else according the the phone company between our village and the hub. At our office up the road, the download speed today was 0.9mbs, I can type 1's and 0's faster than that after a cup of dark roast. LInes

Moral is, I have tried several times to respond to this since you posted, and everytime the browser drops out, and poof... grrrrr.....[arggg IT JUST DID TOO! I had copied most to the clipboard]

I don't even know if it is that, or, the same problem as the forums full of people wailing about the same issue. Lots of knowledgeable replies, no solutions that apply to anyone other than the poster.

Only does it on pages with text entry fields as far as I can tell, and hitting a bunch of backspaces to clear a fumble often triggers the lockup. I put a DOS utility on the taskbar to clear the keyboard buffer.. that theory popped up a few times on the forums so I tried it out. Nope.

Three crashes total on this post. cuckoo cucko

Four.. LOL
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Old 11-27-2015, 09:47 PM
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Posting here is ok on my end just did a speed test.

Last Result:
Download Speed: 57133 kbps (7141.6 KB/sec transfer rate)
Upload Speed: 5956 kbps (744.5 KB/sec transfer rate)
Latency: 23 ms
Jitter: 5 ms
Friday, November 27, 2015 11:46:39 PM
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Old 11-28-2015, 08:00 AM
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[expletive deleted] on you..

Our DSL plan promises 6mbs.. and there are no other options in the area. [I can live on 6mbs, but much less sucks]
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Old 11-28-2015, 03:31 PM
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Lol Mike

I wonder what sort of speeds you get with a smart phone perhaps tether to a 11in tablet when your desk top is in slow down mode.
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Old 11-28-2015, 04:01 PM
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I have to wake up each new page by refreshing it.
The pages go right into System Idle Mode.
I also have to wait for some sort of an Add Service to load it's crap before the page is free to be used.
Quite often I punch out of here without getting anywhere.
I've got a much better connection than ever before [I must have 12,000 posts on dial up] but this site is running as bad if not worse than ever.

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Old 11-28-2015, 07:51 PM
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I have my browser set to delete session cookies and history on exit. I also have second party cookies blocked.
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Old 11-29-2015, 12:20 PM
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Stop your whining you guys should have dealt with 150 baud modems...
Pond Skipper has the idea as far as how to clean up your browser a bit but what you use for a browser can cause issues.
Even with a fast connection and a good browse ie not the dreaded IE, RCU forums still have some "issues".
But even at their best computers still "inhale sharply" more often than not.

What CP said about a lower cg on the short wings is very true, it is worth the effort of having a depressed center section.
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Old 12-01-2015, 04:19 PM
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OK, this is technically a .15 delta and I think it is an all around better design [than the Home Plate style deltas] for low thrust hand launches and ease of control while doing a gentle Speed Pattern.
I can't say which layout is ultimately faster.
It's got the low CG and built in hand grip for launching.
30" x 11" at the root, 4" at the tips for about 225 sq inches and it weighs about 23-24 ozs RTF.
When you lift it by a wing tip, you'll say "That's a heavy little pig..!"
I've never played rough with it to see how fast it can roll, snap roll, etc. It's just to see how fast the Zalp .15 can make it go.
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Old 12-01-2015, 04:26 PM
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Have we seen video of that? Probably but I can't remember..
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