Wednesday, August 24, 2016

Foam ekrano-glider progress

Progress on the foam Chesapeake Sea Monster was delayed by a long weekend getaway (which also caused me to miss both August launches). I still hadn't figured out the entire motor mount/flipping canard design. So, I just started cutting wood anyway.

Here is a photo of the mount dry fit in the deployed position.  It will be pulled up by elastic bands attached to either the side wings or the rear wing. Both should keep the elastic away from the exhaust plumes.  The part I have not figured out is how to keep it in place during boost. One way is to have the motors hang out the front with a bracket to hold them down. But, will a motor eject itself if it is merely touching a flat plate? Maybe I need to have the motors' rear overhang mate with a bracket?

I also can't decide on the motor configuration. I'm torn between eight 18mm and two 24mm. Since I'm running low on Q2G2's, I think I want to reduce the number.

Finally, I wanted to limit the weight of the motor mount parts so I went with a slab of squishy balsa. I'm not worried about the boost but an unsure what will happen if the canard deploys at high speed.

One the original Chesapeake Sea Monster, I was worried about stability. Now I'm worried about everything else.


Tuesday, August 23, 2016

Building tips from Chris Michielsson

Apogee's latest newsletter has some great tips on: adapting a 3/16" lug for a 1/8" rod; improved use of wadding; hiding sticker/decal junctions/overlap; thinning down your tri-fold shock cord mounts; masking tape removal; tying a better shock cord knot; and, cleaning paint over-spray.

I'll steal his thunder and give a hint on the last one - use a Mr. Clean magic Eraser. I very lightly scrape the overspray with a hobby knife blade but will have to try this one out!

If you don't already do so, check out Chris' great blog.

Smoke by the water, a fire in the sky.

In Case You Missed It...

Tuesday, August 16, 2016

"Is that X-15 Model Really the Right Color?"

Dean Black has written a paper discussing the true color of the X-15s, why it is that color and how to make your model's color true to scale. It's a .pdf and not hosted anywhere so I'll provide a teaser. He had given permission to distribute it so if you leave an email in the comment section, I will send it to ya'.
Is that X-15 Model Really the Right Color?  
Is the X-15 really black? The short answer is “No”. For a variety of reasons X-15 appears black in most photographs, but outdoors in direct sunlight X-15 is an iridescent dark blue. That’s right, blue, or more specifically “gunmetal blue”.   ....

Sunday, August 14, 2016

It glides! It glides!

Well, I consider the first flight test a success. It seems to glide when hand tossed across the yard. A little better against the wind than with it. And the foam survived the initial set of hard nose dives without losing any parts.

I merely wedged on a canard that is sized like the CSM's forward motor  mount. The cant angle was chosen completely unscientifically...just like the rest of the build.  For a few milliseconds, I had thought of looking at a model airplane calculators to determine the proper CG. Instead, I taped on four weights that moved the CG to a couple of inches ahead of the main wing's leading edge. This seemed reasonable from what I remembered from my work with the big F-104 PMC. With four weights it nose dived hard and fast. With three, a little less so. Two looked promising on half the flights. With one, the CG is a couple of inches behind the leading edge and the glide isn't too bad. Close enough for a proof of concept for a project whose future is ambiguous.

It's still a long way of being flight ready. I am no closer on figuring out the motor mount and canard release mechanism. You will note that, in its current configuration, it has a large canard-like winglet. All my initial thoughts have led to two smaller ones. I probably should rig up something like that. Anyway, I am currently satisfied that my question is answered - an ekranoplan can glide.

I might end up gluing on the weight and the canard and giving it to the grandkids.

Ekranoplan: gliding Chesapeake Sea Monster

Friday, August 12, 2016

More ekrano-craziness

A while back, in a futile effort to hijack yet another TRF thread, I asked whether the group thought that an ekranoplan like the Chesapeake Sea Monster could be made to glide if the forward motor mount was pivoted like a canard. Displaying good sense, no one responded. During my beach withdrawal, this question resurfaced. And, now I'm going to try to find out for myself.

My general thought is to make a skeleton-style model out of craft foam board and to power it only with the forward mounted motors. The body design is simple but there will be a lot to work out on the pivoting motor mount(s).

Today I roughed out the part dimensions and found that I had a sheet of black foamboard. I now have most of the parts cut out and the first two are being glued together. Although I will continue pondering the motor mount, I plan to just attach a pre-pivoted foamboard plate to see if I can get it to glide. No reason to go further if that doesn't work out.

I have little hope that I will succeed as my last two glider KITS never flew properly. In my first foray into rocketry, I built two that flew wonderfully, one directly from a plan and one scratch built but motivated from a design that I had seen somewhere.  Maybe the latter bodes well for the ekranoplan since it is a canard design with two wings and winglets?

This is generally what the old one looked like, but the dimensions are off.

Canard boost glider 1960s

NASA Ames' wind tunnel goes psychedellic

NASA engineer Rockergirl Nettie Roozeboom checks out a generic launch vehicle model covered with pressure-sensitive paint that shines when exposed to blue light. The test article is seen mounted in a wind tunnel at NASA's Ames Research Center in California. Credit: Jim Banke
NASA Aeronautics Research Mission Directorate

This new paint luminesces when exposed to blue light. Its intensity varies with pressure so NASA engineers can visually see the how structures perform in their wind tunnels. Far out, man!

Sunday, August 07, 2016

A sticky formula

primer + clearcoat + sharpie ink + Rustoleum gloss black = sticky after 3 days

The Interwebs say Rustoleum black often takes 4+ days to completely dry. I don't know exactly how long it took on the Sat V, but it was totally dry after 11 days.

This stuff will be kept only as a last resort.