Windscreen
Posted: Mon Dec 15, 2014 11:21 pm
by eppre
Hi guys,
I am working on my windscreen and want to know how you guys did yours. Did you install the bow and then match the windscreen to the bow? Did you set the bow to the 17 + inches on the plans and then match the windscreen to it?
I have a pre-cut screen and it is high and needs to be cut down. I need to cut about a half inch of each side in the front and don’t know if I should carry that cut the full length of the side or if I should angle it.
Thanks for any help.
Peter
Re: Windscreen
Posted: Tue Dec 16, 2014 12:09 am
by tonyr
Hi Peter,
Trim the windscreen at the front carefully to fit the front flange.
Do not trim off the rear sides the same amount, so angle your cuts along the side.
You want maximum material across the rear bow.
You set the bow to the windscreen arch.
This avoids a dished look for the windscreen to canopy transition.
Following the above here is how mine came out…
Re: Windscreen
Posted: Tue Dec 16, 2014 9:23 am
by avee8r
I thought I’d mount the windshield one day and decided to get the best looking lines I would need to do other things first. I mounted the engine so I could fit the cowling. Then I used a straight edge or string along the top of the cowl to set the windshield bow to the height of that extended straight line of the top of the cowl. Then you can work the canopy to fit the remaining opening. That should give you that sleek Sonex shape.
Happy Landings
John
N50NX
Re: Windscreen
Posted: Wed Dec 17, 2014 10:46 am
by DCASonex
When installing mine, pushed the bow up to make full use of the supplied Lexan sheet. Bow was about out with about 3/4" higher than plan for extra head room and forward visibility, and nice clean line with both the original Sonex canopy and the current Todd’s canopy. Also glued a double later of black felt on the bow strap before installing wind shield which makes a bit of a seal to canopy.
David A.
Re: Windscreen
Posted: Wed Dec 17, 2014 12:49 pm
by fastj22
As others have mentioned, use the full amount of windshield material at the bow and only trim the firewall section. You want maximum bow to avoid the porpoise nose look.
Re: Windscreen
Posted: Thu Dec 18, 2014 4:04 am
by sonex892
I followed the radius’s on the plans. Viewed from the side there is a smooth transition from the windscreen to the canopy and no dolphin nose. Viewed from the front though, there is some dolphin nose lower down the sides. I doubt it is possible to eliminate the dolphin nose totally with a flat wrap windscreen.
Caution with the plans. The canopy radius is drawn outside radius, the windscreen bow, drawn inside diameter. Not noticing and making an error here places the windscreen bow real low and is possibly the main reason for dolphin nose. Sonex may or may not have altered the drawing since?
Steve
Sonex 892
Re: Windscreen
Posted: Thu Dec 18, 2014 10:56 am
by eppre
Thank you gentlemen for you responses they have been very helpful.
Peter
Re: Windscreen
Posted: Fri Dec 19, 2014 4:53 pm
by grevaly
Hey Guys, I have already done my rear windscreen bow to the plans and drilled it.
Have I made a mistake? Should I lay the canopy down to see if the lines will be good?
I notice some builders prefer to place the rear bow up some utilizing all of the material in
the blank windscreen sheet at the rear. I have just finished my motor to the point of doing the rear mount
and ignition stuff. I wanted to go ahead and get this done so I can get going on the cowling. I would have installed the windscreen
assuming it would look fine to the canopy. Should I look further down the road to have this all blend in?
Thanks, Mark
Re: Windscreen
Posted: Fri Dec 19, 2014 9:27 pm
by fastj22
Have you cut the windshield? If you find the bow is too short, you can aways just put a new bow in. If you’ve cut the windshield, then you really are committed to the shape. It might be fine. And the porpoise nose look isn’t bad, it just doesn’t have a clean flow from cowl to turtle deck.
Re: Windscreen
Posted: Sat Dec 20, 2014 10:50 am
by grevaly
No, I have not trimmed the windscreen yet. But I do not want somebody saying Hey look at the porpoise nose on that…
That nose should come with a bowl of soup…Oh, it looks good on your plane though.
I was not aware of adjusting this area for optimun appearance. I know I spent a couple hrs fine tuning the bow to get a nice curve.
I got it from sonex cause I thought it might be better shaped than I might have done, but it kinda looked like it was just
formed around a tree. As I recall it also has a particular little bend at the bottoms where it transitions to the fuselage.
I am glad I caught this thread, now I know to look at the shape before I trim the windscreen.
Re: Windscreen
Posted: Sat Dec 20, 2014 11:18 am
by DCASonex
Aside from eliminating porpoise nose, raising the bow usually increases forward visibility. If you decide to make a new bow, one trick I used when forming it was to tap the ends of the tube 7/16-14, plug one end with bolt, fill with sand, bounce it on end till sand well settled, fill to near top and install second plug to compress the sand. This helps keep tube from collapsing. it is much less expensive to buy and ship a straight piece of tube than a formed one from Sonex. Be sure tube is long enough to leave about 8-12" of straight tangent on each end as that makes forming easier, and the tapped ends will be cut off. I made a big tube forming jig by simply saw cutting a half moon shape from a 1-1/2" thick board and running 1/2" ball end router around the edge. Radius does have to be significantly smaller than finished radius due to spring back. Same rig is great for tweaking the canopy bows to match front and rear. E-mail me if want photo of that bending rig.
David A.
Re: Windscreen
Posted: Wed Jan 28, 2015 8:43 am
by ScottM-Sonex1629
Could someone who is near their set of plans (or have a great memory) let me know what the radius is specified for the windscreen bow on the plans?
I recall something like 17-13/16" +/- and the last 3 deg. is straight.
Want to draw this in cad and plot a full scale template today (I’m already at work and forgot to get the dimension before I left home)…
Many thanks,
Re: Windscreen
Posted: Wed Jan 28, 2015 9:26 am
by Rynoth
ScottM-Sonex1629 wrote:I recall something like 17-13/16" +/- and the last 3 deg. is straight.
Scott, I just looked and you nailed it. 17 13/16" to the inside radius of the bow, with the last 3 deg straight.
I’ve done most of my windshield in the last week, and will note that I ended up needing to put an additional small bend an inch or so down the straight part (just above the top of the longeron) in order to smoothly insert the bow through the longeron holes. Otherwise it wanted to put a twisting force on the longerons. This probably depends a bit on the longeron holes themselves, but I tried enlarging them slightly and still needed to add the bend. Fits well now.
Re: Windscreen
Posted: Wed Jan 28, 2015 10:17 am
by Gripdana
Check your PM. I can go look at my plans right now.
Re: Windscreen
Posted: Wed Jan 28, 2015 11:16 am
by ScottM-Sonex1629
Thanks Ryan, and Dana. I guess my memory is better than I remembered…LOL