06May2014

Make A Windscreen For Observing

 
Windscreen by car at Spruce Knob

Here is a picture of the screen in action with the author Eric at Spruce Knob, West Virginia.

Reality check: I’ve found that schedule 40 PVC pipe fittings do vary slightly in size depending on the manufacturer and even the individual pieces. I’ve had a couple of fittings weaken.

That was due to very high winds and I used a different brand to replace them. Some pieces fit, some don’t. I recommend you buy a few extra fittings or save a scrap piece of your pipe and bring it with you to the store to make sure replacement pieces will fit with the right amount of friction.

Some of the best observing locations are also the windiest. Don’t get shut down again when it’s crystal clear but too windy to see anything but a blur in the eyepiece. This windscreen made of PVC pipe and fabric was my answer. It blocks the wind with very little blow-by, keeping my telescope steady and me warmer. It breaks down into pieces and fits into a custom carrying bag that my wife crafted. (She also did the fabric screen.) The measurements provided here will produce a windscreen of the following dimensions: height – 57″, width – 83-1/4″, depth – 57″. You can adjust the dimensions to suit your needs, and you can also simplify the fabric screen.

Winscreen with telescope

Eric from Astronomerica with his 10-inch telescope well shielded. The windscreen will cut off the horizon in one direction, but for him, that’s usually west, and not where he observes a lot down low, as these are “departing” objects.”

Windscreen front view

Front view.

Windscreen side view

Side view.

Windscreen rear view

Rear view. Note the 5 lb. barbell weights that help to hold down the corners. I’ve actually stopped using these for the most part, and instead just put a couple of tent stakes behind the front lower crossbar. But the weights can be used if you’re on a surface like a parking lot where you can’t use stakes or if it’s especially windy. Even though the connectors are 90 degree angles, the sides can be spread a bit to provide a little more room for the scope and gear.

 

Nylon cord clips to screweye

The two nylon cords that form an “X” provide rigidity to the structure. They clip on to screweyes in the corners.

Flaps at top with Velcro

There are flaps of extra material that wrap over the PVC and are held by Velcro pieces.

Velcro tabs at bottom

Velcro tabs are sewn onto the bottom to wrap around the PVC and fasten to stick-on Velco pieces on the PVC. Note the tent stake on the left, the preferred method of keeping the thing from becoming airborne. I marked which piece of pipe is which with a Sharpie permanent marker. This helps during set up.

lower corner

Here is the optional barbell weight arrangement. The weights are slipped on while putting the pipe together. The lower end of the nylon cord is also clipped here.

back end of windscreen

The left side back end, showing the flaps, optional weight, and the pipe joint.

Windscreen parts

The unassembled parts, minus the weights. I keep the nylon cords in the pocket in the bag. Set up and breakdown take about 10 minutes. The PVC pieces fit together with friction only.

All pieces are 3/4″ PVC pipe. The longest single pieces are 54″ to fit across the back seat of most cars. Measurements are as follows (pipes numbered from left to right in the picture above):

1. Left diagonal, front half – 35″ with straight coupling on one end, 135 degree elbow and 2.5″ piece on other end
2. Right diagonal, front half – 35″ with straight coupling on one end, 135 degree elbow and 2.5″ piece on other end
3. Left front upper crossbar – 39″ with straight coupling on one end, 3/4″ to 1/2″ reducer on other end that screws into a 90 degree elbow with 1/2″ inside-threaded side-outlet (drilled for screweye insert)
4. Right front upper crossbar – 39″, bare on one end, 3/4″ to 1/2″ threaded reducer on other end that screws into a 90 degree elbow with 1/2″ inside-threaded side-outlet (drilled for screweye insert)
5. Left diagonal, rear half – 35″, bare on one end, 135 degree elbow, 2.5″ piece, and 90 degree elbow on the other end.
6. Right diagonal, rear half – 35″, bare on one end, 135 degree elbow, 2.5″ piece, and 90 degree elbow on the other end.
7. Left front ground crossbar – 39″ with straight coupling on one end, 3/4″ to 1/2″ threaded reducer on other end that screws into a 90 degree elbow with 1/2″ inside-threaded side-outlet (drilled for screweye insert), stick-on velcro to match velcro tabs on fabric screen
8. Right front ground crossbar – 39″ with bare end, 3/4″ to 1/2″ threaded reducer on other end that screws into a 90 degree elbow with 1/2″ inside-threaded side-outlet (drilled for screweye insert), stick-on velcro to match velcro tabs on fabric screen
9. Left side ground bar – 54″ piece with stick-on velcro to match velcro tabs on fabric screen
10. Right side ground bar – 54″ piece with stick-on velcro to match velcro tabs on fabric screen
11 & 12. Front uprights – Two 54″ pieces. My fabric screen is sewn with a pocket running the length of each corner into which these pieces slide. I leave them in and roll up the fabric around them.

A note on fabric – check the opacity and tightness of weave of the fabric you choose, so that it will block wind and light well. The material I used has some kind of waterproofing to it, but you could use spray waterproofing (Scotchguard, for example). It will get very wet if you encounter a lot of dew. I also like to keep it a color that blends in with the surroundings, though it has been mistaken for a duck blind (in a no-hunting zone!).

Windscreen bag

All packed up and ready to go home. Article adaptation: Eric c/o Astronomerica

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