#10 Trailer Modifications + Acquired Trainer Easy Riser

My apologies for those following this blog.  I really did not intend to take such a long break from the project but summer got in the way and after my fiasco with the covering process I was having a hard time getting back into it.  A significant part of this project involves finishing the completely enclosed trailer shown in the very first post. I completely removed the shelf system and relocated them to a position about 4" lower that made use of all the wasted headroom over the lower wing set left by the rib camber I had not taken into consideration originally. There was also a considerable amount of epoxy/ fiberglass repair that needed to be done and a reconstruction/re-design of the end panels to accomplish a weather-resistant seal on both ends.  I also removed one of two leafs in the suspension system (the photo is after I removed the small leaf) and added shocks on both sides to smooth out the ride.The shock/springs came off a Harley Sportster mod job....still need to see if they are too stiff.

Currently I'm working on the bed that I will need to attach the box to and then I'll try out the suspension system with a full load.

Mid July I had an opportunity to inspect the covering of an Icarus II that was done by someone I knew to be a “craftsman”. I figured this would give me an idea what was possible in doing a good job of covering this type of airframe. Here are a couple of shots showing the leading edge area and the rib sag.

My conclusion after looking at this was that it is possible to get a very nice, wrinkle-free covering with very little inter-rib sag. Keep in mind that nitrate dope keeps on shrinking years after it is applied so the rib sag you see in this picture must have been near zero when the glider was covered.

In July, I flew Fort Funston and happened to meet a former Easy pilot who ended up giving me his Easy along with the car top box he built to transport it. He flew it one last time in what I guessed to be winds at the Fort over 20. He is taller than I am, maybe 6' and probably has about 25-30 pounds over me and he had all he could do to maintain control on the ground with the glider. I learned a lot by watching him fly it. He used no rudder control on the ground (said it really wasn't effective). He told me that pitch control is really all you have plus body torque to get and keep the wings level while ground handling. Once in the air flow he had a lot of pressure on each hand placed forward on the twist grips to keep the nose down. He could pull down a high wing by pushing down harder on the high side but I never saw him do anything with the rudders. I had to come in twice at his request before he launched to pull down a wing that he could not pull down on his own. Once in the air it looked really sweet.....easy, comfortable flying position and an effortless landing. He did tell me to start flying it before I put too much more time into my project to make sure I am happy with it's performance. He said the sink rate wasn't all that good. I expect I will do significantly better than he did since I am quite a bit smaller that he is. He had it rigged with a compressed air chute deployment system that a friend of his was making at the time and he used it on that last flight. I will need to rig my own system once I start flying it at high altitude sites. Here's a shot of me on the way home from the Fort with Darrel Robbins' Easy in it's car top case and my Comet on top.

Here are a couple video links to Darrel's final flight in it the day I returned to Oregon.

http://www.youtube.com/watch?v=YPUnctxRzMk

http://www.youtube.com/watch?v=Oa3H-MeA738

Keep in mind that the wind at launch was gusting over 20.

The glider itself has some tears in the sail that I will repair before taking it out. Here it is shown in it's new home (the box I built with the reconfigured shelf mod I did in June).

Had over an hour talk with Brian Porter last night on the phone where we discussed various topics including things to pay attention to in building the glider and also tips on what he found worked for him in flying it. Brian was one of the experts at flying rigid wing hang gliders back in the day. He won the Escape Country meet with the Easy Riser in 1976. He mentioned increasing the washout to a 2 5/8 inch block on the fabrication frame vs 2 ½ specified in the plans. This was thought to improve the sink rate. I asked him about covering and his comments indicated that he was able to pull a lot of spanwise tension in the cloth without dog legging the frame. No tips on how he was able to do this. It could be the fact that I tweaked the frame when I crashed is setting mine up to dog leg with even moderated spanwise tension. I am beginning to believe this is the case. If true, then my only solution is to go light on both spanwise tension and chordwise tension living with a few wrinkles or bend the frame back to straight again. He said the glider is prone to pitch sensitivity and will pop up and down in thermals.You get used to it after a while. If properly built, the glider should trim out so that once in the cage, feet on the leading edge, you should not be able to stall the wing even with your back up against the rear of the cage but this should put you at minimum sink right above a stall. You have to let your feet down to get it to stall. You can see him drop just one leg and then bring it up again as he adjusts his approach for the spot landing in the video link I'm including below. He also fabricated handles that he mounted 90 degrees off the twist grips to aid in rudder deployment. He said you'd be surprised at how tiring it is to work the twist grips for an hour. The front negative wires were replaced with 3/32 cable since they will see a large load if the wing goes negative. The plans called for 1/16. He recounted inspecting a wreckage where these cables broke when a fabric detachment occurred and caused an involuntary tuck. Deploying both rudders will pitch the nose up since they are above the center of mass in the loaded air frame. This video link to YouTube shows footage of Brian doing an approach where you can see how he moves his legs and how the glider responds as he flies into ground effect and flares.

https://www.youtube.com/watch?v=eHlsQOOt73Y

The current state of the project is both upper wing panels are ready to cover. I have the pre-shrunk material and am winding down my summertime activities. I hope to begin covering again in September. My first priority is to finish the trailer so I can move the wings when I finish them.  Without the trailer being ready, I have no way to move the wing panels to and from the shop which is about 8 miles from my house (I have no wing frame at this shop).  I am also anxious to repair the fabric on Darrel's glider so I can begin to take it to the beach and learn how to fly it before winter sets in.....decisions, decisions.

#9 Covering & Sealing With The New Material

Got the new material (now thought to be the right stuff which turns out to be a bad assumption) and re-started the covering process. The leading edge glue line I had penciled in on the first attempt was still visible so we used that to glue this bottom piece to. The bottom “blanket” of fabric was then rough cut to span length adding 6 inches of extra cloth off the tip and the root struts. The factory edge was very smooth so we just glued it on beginning at the middle and moving out toward the tip and then out to the root end. We wet glued this leading edge line meaning we applied wet glue and then immediately set the fabric in it. You can also pre-glue full strength and then come back and use 50/50 MEK/glue and set the fabric that way which I believe is what the plans spelled out. It's a real guess as to how much spanwise tension to apply. Even the moderate amount we applied created a spanwise sweep about 3 inches beginning at that internal strut. There just isn't anything in the frame to keep that from happening. After gluing the leading edge of the bottom blanket, we applied glue to the bottom rib cap strips and then came back and mashed the cloth into the half dried glue with 50/50 glue/MEK mix. Massaging this in gave fairly thorough and consistent cloth penetration with no pull up or separation. The tip and root ribs were wet glued since it was much easier to handle the cloth over wet glue at the ends of the panel. There was some detailed trimming to do at the root strut where the cloth has to be terminated. This was done with the soldering gun blade tip and basically followed the outer edge of the root gusset plate where the chafing tape stopped. Here's a shot of the finished panel prior to detailing with the iron. Most of the large area shrinking has already been done and you can see the inter-rib sag that occurred as a result.

The sag measured nearly an inch in the worst bays. I released the leading edge seam on the worst bays and relaxed it back to where there was only about ½ inch overlap left and gained back a lot of the airfoil.

 At this point I am getting the feeling that there is just too much frame distortion to expect the panels to fit together well enough to set up or fold down not to mention the inter-rib sag which looks severe to me but I continue with the sealing step anyway.  You can easily see the dog leg sweep on the leading edge caused by the fabric tension.  It starts right where you'd expect it to....at the internal diagonal rib and out to the tip.  I took the time to do some detail work most would skip such as these patches over the gusset holes. Even though I did a fair job of cutting the gusset slits, these patches really clean up each gusset position.  I drew the pattern out using a drafting compass and cut it out using a pinking shears.

Starting the sealant coat (Poly Brush in this case).

The gusset patch after sealing. It really did look better with the patch than without.

A shot of the bottom of the panel with the first coat of sealant complete.

Top of the same panel at the same state. I could have used clear Poly Brush but felt being able to see where I had been was more important which is why it is rust colored (their standard sealant color). I planned to paint the wing so this would all be under a couple coats of paint when I'm finished.

After all this, I finally verify that the original plans and kit for this glider involved applying pre-shrunk polyester dress lining material using standard aircraft fabric cement (Super Seam) and nitrate dope referred to now days as the Ceconite process (except for the fabric of course). All my effort and hours of detailing the spars using the small iron was just practice. I stripped the airframe and place an order for pre-shrunk polyester for the material used up during the first attempt at covering. I won't get back to working on recovering until September most likely. The next post will cover some of the things I'm working on this summer that are directly related to the project including reconfiguring the trailer, inspecting an old Icarus cover job and inheriting a completely finished and flyable Easy Riser during my annual trip to fly at Fort Funston near San Francisco.