wing pods

[courierguy]

A buddy who's a well known Idaho composites guru is making these, I'm doing the BETA testing, and so far results are as expected. They are 5' long, with access being through the front, which pops off with two snap catches. Lots of room inside with no protruding fastenings, think of them as streamlined stuff sacks that detach or attach in 5 seconds.

Think of that for a second, you arrive at JC loaded to the gills, and your buddies are just rolling out to hit the Big Five, (what, you think they were going to wait??) pulling 4 pip pins and leaving the loaded pods laying on the ground. You almost instantly lost 60 pounds, while still having your stuff protected from the WX or whatever.


Speaking of stuff sacks, I am leaving mine at home, now the fart sack, the tent etc., all go directly into the pods, saving time, hassle and a bit of weight. They have handles so when you check into a hotel, a hotel that caters to potential terrorists I guess as they look like bombs, you'll be looking sharp!

I said "results are as expected", that not entirely accurate, they seem to be better. As in lower landing speed, no perceptible in flight drag, and maybe better climb. There I said it, blast away! Testing continues, but right now, after over 20 hrs of flight with them, I can for sure say there is no performance hit that I can tell, and unless I just had "lucky air" the last few landings, they may inexplicably be allowing a bit lower landing speed, let's call it some kind of bastard vortex lift or something. A more exhaustive series of test to determine any differences in the extreme low end will soon be forthcoming, and if I find no difference at all I won't be surprised. But damn it right now I think we may have stumbled onto something, or at least at worst found a way to carry more crap without any performance hit that I can discern. I posted more extensively on this on BCP, but thought I'd bring them to everyone's attention here.

 

[eskimo77]

If these make it to market homeland security will be getting tons of calls from the flightless masses.

 

[courierguy]

Agreed, so far, that is the only drawback I've seen!

That tape on the aft lift strut BTW is because we had one pip pin that was too long, long enough to contact the lift strut if it moved, it didn't but I taped the strut just in case.

 

[Traash]

What's the load analysis on the strut?

 

[courierguy]

Good question, I sure don't know, but I did pack my usual camping gear in each pod, and then flew over 20 hours on a couple XC's recently, making 4 off airport landings on the way, and felt comfortable doing so. It was only about 30 lbs inc. pod weight. Like any external load I guess, a little common sense goes a long way. I don't see them being used for carrying bags of fuel for instance, more all the light but bulky stuff.

The pod strut attach bracket itself is carbon fiber, in the S-7's case we have eyebolts so it's bolted on. He's working on a CF cuff with a embedded attach point that would slip around any lift strut (diifferent cuffs for different strut profiles) positioned by the jury strut and be clamped into place.

 

[ndill]

Paint them navy gray/blue or olive drab add tailfins and a sharks mouth that would really get the Sheeple going.
But in all seriousness I would put Cargo or Cargo Pod in large letters on the side or bottom. Would also be good for carrying a small
rifle in the lower 48. I Don't imagine a rifle case on the struts go over well.

 

[Carey Gray]

Were these under your airplane at Hood River?

 

[courierguy]

Yes, and what a museum they have there!

My takeway moment of that event was when I was looking at that all carbon gyroplane, looking like some something out of the Jetson's, and right next to us the Miss Veedol replica fired up and taxied out.

 

[Carey Gray]

I'm not much for fly ins, but Hood River is always fun.
How soon are they going to be available? Looks like a great idea.

 

[DarrenLucke]

wonder how they'd look under my rv-4, lol..... speed rated??

 

[Tim]

Great idea

 

[courierguy]

Carey: Check with Joel, I'll leave all that to him, I'm just one of the test dummies. dirtfly7@yahoo.com

Darren: They'd look even more bomb like, and I don't think your greater speed would effect them much, dream on!

One thing I noticed, when you set them down on a concrete floor, depending on where the stuff inside vertical CG is, they may roll over a bit. If I had a custom matched to the airplane paint job, that'd bug me a bit. A couple streamlined bump outs that would make it stable when set down, something to keep the bottom down, may or may not be worth messing with. Setting them down in grass it's a non issue, or anything other then a concrete floor. In my own hangar I have taken to just throwing down an old bath towel I use for pre soaking the windshield, and setting them down on that, problem solved. I also thought the next time I bed liner my Airstreaks, I could slap a coat or two on the pod bottoms, though it'd be a shame to mess with the slick finish.

 

[skywagon8a]

.. In my own hangar I have taken to just throwing down an old bath towel I use for pre soaking the windshield, and setting them down on that, problem solved.

And then you are going to put that towel back on your windshield after you pick up some little pieces of sand on the floor? :roll:

 

[courierguy]

Yes, but I swept the floor first, (a good smooth finish on the concrete helps here), and also shook it out afterward, and when I do use that old towel to pre soak the bugs, I wet it down first and then just lay it on the windshield without swiping it at all. Later I lift it off, again without swiping. Then I hose it off, then and only then do I take the microfiber and warm soapy water and start the final cleaning. Then I rinse again and throw an old quilt (and this is kept pristine) over it. Then, when dry, I hit it with the Pledge to get the mildly hard water from my well spots off. Re-reading my earlier post, agreed, it sounds careless, not so! If I decide this will be an ongoing event, I'll get a dedicated pod pad. This was the first time I had taken a loaded pod off and the towel was the handiest thing.

Though I have an aftermarket plexi windshield on the S-7S, I have had lots of experience with lexan 'shields, as a result I am probably more anal then most about how I care for it. Over 1700 hrs now and it's looking real good so I'm doing something right.

 

[ndill]

I wouldn't be that worried about someone getting excited about them in flight other wise there would be long-ez guys being arrested all the time. But I would be careful when you took them off to go to lodging. Around an airport I think your fine most people would figure it out.
Also as far as the load on the strut I'm sure someone like Doug Keller could figure it out pretty quick with all the CFD engineering type software programs that just make my brain hurt.

 

[skywagon8a]

...Also as far as the load on the strut I'm sure someone like Doug Keller could figure it out pretty quick with all the CFD engineering type software programs that just make my brain hurt.

The loads are on the jury struts and their fasteners. Not the wing struts.

 

[ndill]

You correct I was thinking more of the general over all aerodynamic affect on the aircraft plus the plus the actual mechanical loads on the jury/wing struts. thinking about all math involved makes my brain tired.

 

[skywagon8a]

Actually all you need to do is to break it down into small pieces. Look for the weakest component and go from there. I don't have any engineering training yet when I applied to the FAA for an STC which required a stress analysis for a fuel tank installation, I did the calculations myself. The FAA engineer said that is not the way that he would like it done yet he would accept it because the answer was there. I got the STC.

 

[JimC]

The static loads and steady-state dynamic loads are simple and straight forward. The flutter analysis is not.

 

[courierguy]

Flutter? I suppose anything is possible, including aero effects on the tail feathers in a slip. That's why they will probably be for experimental only. Anyone comfortable with past experiences with oddball external loads would find these pods pretty obviously airworthy. We experimental types are used to this type of common sense eyeball engineering, for better or for worse.

Dynamic lift is what we seem to be getting at high AOA, just like an airship does when the elevators raise the nose/ drop the tail. In fact, the shape of these is identical to the most aero efficient airships. NOT the old zeppelins, but the "newer" zeppelins, they were much less draggy then the zeps from the teens, that had a constant dia. for most of their length.

 

[JimC]

Remember the early flutter problem on the Cessna 310 wingtip tanks?

 

[JimC]

What volumetric drag coefficient did you achieve?
I note in passing that the R-101 (designed by the British Air Ministry) had a much higher drag coefficient and lower payload than the privately designed R-100 (I don't remember who did the VL curves for it, but Nevil Shute Norway - better known as the author Nevil Shute - was the senior stress engineer for R-100).

 

[Lasater]

Can you put a quick release on them triggered from the cockpit? I am thinking high speed cargo drop or dam busting practice. If you want the cargo to survive, a parachute may be in order. Build enough, and Supercub.org members can challenge Amazon's drone delivery program. How about cold (slightly shaken) beer delivered within 50 yards of your location within 30 minutes or your money back?

 

[courierguy]

What volumetric drag coefficient did you achieve?
I note in passing that the R-101 (designed by the British Air Ministry) had a much higher drag coefficient and lower payload than the privately designed R-100 (I don't remember who did the VL curves for it, but Nevil Shute Norway - better known as the author Nevil Shute - was the senior stress engineer for R-100).

Beats me, a pretty decent one would be my best guess. I had an hour to kill the other day while on a crane job, and started researching some old data on zeppelin design. One thing that stuck in my head was how the first ones were more built from a "get as much hydrogen as possible in there" point of view, max cubic feet was the goal. Only a few generations later did they fully realize the benefits of a design more ellipsoid shaped (my new word for the week), and the drag reduction combined with newer weight saving structures brought the big Zeps into their golden age. Looking at the side profile of the pod, it appears to be pretty similar to those latter airships. I need to ask Joel how exactly he came up with the shape, I do know that it all started when he found a couple spare spinners, and one thing led to another!

As to how he defined the fineness ratio and/or taper, whatever it's called, I'd guess he just eyeballed it, and it sure looks about right to me. On a similar note, back in the heydays of ultralights, there was one popular design that had a great safety record and sold in the thousands, it featured something called a 7.50/16 airfoil. That's right, the designer used a popular truck tire size of the time to bend the 1/2" aluminum ribs around to get the ideal curvature, true story! Someone needs to ask him what volumetric drag coefficient he achieved..... he'd get a kick out of that. What's interesting tome, is when I see something that works well, but was achieved by eyeball and intuition, when in retrospect the numbers are crunched, often they come out pretty good, genius at work I guess, that and luck.

 

[JimC]

Luck always helps me a lot.
I've had good eyeball results using a 1/4" square stick of balsa. Bending it to shape forms a least work curve that usually flows fairly well.

I've always been fascinated by the performance differeces between the superb R-100 and the fatally flawed R-101. They came after the days of the early zeppelins though, being designed about 1927-28.

 

[cubscout]

And has anyone else noticed how nicely the pod nosecones pick up the lines of the cowl green & white "swoosh" paint design? A very nice design by the way, at least to my eye--sort of suggests the late '50's factory Supercub/Dave Kirsten's Green Hornet, without near as much masking layout.

Courierguy, thanks for sharing this, I've seen quite a bit of Joel's work, and he's a very talented guy.

Thanks. cubscout