[Bob Kuczewski]

I feel compelled to issue my standard warning that adding power does create a number of additional failure/accident modes that may not be obvious.

It sounds like everyone in this discussion has far more experience than I do, so you probably already know what I've said is true.

I'm not offering the comment as any kind of a revelation, but as a gentle reminder to ... be careful.   

[Bill Cummings]

My concern would be with a high thrust line that is practically guaranteed to tumble a glider after a stall.

[Rick Masters]

When the big ultralight craze hit in the 1980s, we lost an awful lot of hang glider pilots.
There was a lot of rationalization coming from the best of us, that we could use ships like the Lazair to gain altitude, then soar.
It sounded great. George Worthington pushed this idea.
Art Scholl told Don Partridge that Bishop would be the best place for an ultralight race in the country.
Then Art went down in the Pacific...
So Don and George came up with the idea of the Ultralight Soaring Trials at Bishop Airport in September 1982.
It didn't turn out so well.
https://web.archive.org/web/20110718085125/http://www.cometclones.com:80/legend.htm
Then Don got killed on a powered Mitchell Wing...

The paraglider yahoos are going through the same thing right now.
Busloads of them are getting killed right now on powered PG.
Same thing. History repeats itself.
Incredible. Even more stupid than ultralights because of deformation, pendulum and drag.

Risk doesn't go up linearly when you add power.
It's geometric. I think of it as a factorial increase of risk.
For me, I don't want it.
For the US Hawks, it ain't recreational hang gliding.
Steer clear of it.
If you think you gotta tow, you have to invite power in.
That's where we part ways.
I've said it before.
Freeflight is running off a mountain into the sky.
No batteries required.

[Bob Kuczewski]

Thank you again Rick. That's at least the second time I've read the account you linked. It was just as sobering as the first.

Thanks for helping us understand things we would never know without you.

[Frank Colver]

When anybody is posting in reference to my post about "e-assist glide", please remember I'm talking about a model airplane sized propulsion system. Motor about the diameter of a quarter or silver dollar and maybe 1 or 2 pounds of thrust. The glider would not be able to climb or sustain altitude for very long with so little power. Flatland wing running with this little push into short glides could be fun. Like students having an instructor running along with gentle pushing on the glider. Extra push at launch to start soaring flight at Dockweiler. Power assist kiting. The list goes on..........

But yes, I agree, this is not a club or a forum for powered ultralights.

Frank

BTW - The two mountain bicycles I ride now both have a little e-helping hand when I want it and i'm doing a lot more riding now. Purists don't believe in that.

[Bob Kuczewski]

Hello Friends,

I just got a very nice message from Ground Slammer asking if he might be posting in the wrong forum.

According to our conventions, the Blog Forum has been open to all flying-related topics. A quick check of the topics will show that we allow discussions of all kinds of flying contraptions.

Also, the Blog Forum is a place where the Blogger (person starting a topic) should be able to control the content and flow of the discussion. I honor the requests of any Blogger to remove any posts in their Blog topic that they want removed.

Technically, the person starting a Blog topic should spell out the kinds of participation they want (or don't want) in the opening post of their topic. The default has "officially" been that others shouldn't post to a blog unless invited in the first post. We haven't really been following those conventions and I know that I've posted to Blog topics without being explicitly invited.

In this case, discussion was invited about a design, and some of the comments (including my own) have strayed a bit from the design discussion.

So let me accept the blame for being a bit too casual about enforcing our rules. So far, it's worked out pretty well, but maybe it's worth revisiting our procedures.

Ground Slammer, it's your Blog, and you're the one to make the final decisions. I officially apologize for my participation in making posts that may have been inconsistent with your intentions in this Blog. Please let me know what you'd like me to do to fix it. I can remove any posts that you want removed. They will get moved to the special "Removed Posts" topic. You're also welcome to start another blog by duplicating your first post and we'll try to do a better job of staying on topic. Or we can continue forward from here with a few "lessons learned" (my reccommendation). It's up to you. Feel free to call me if you want to discuss it.

I'm sorry for any inconvenience.

[Rick Masters]

I think it's a fine topic for discussion.
The last time I flew on an ultralight, it was with a highly experienced hang glider/ultralight pilot using state-of-the-art equipment.
He's dead. Made it five more years, then whammo. Went down in an orchard.
He'd be alive if he'd stuck to hang gliding.
Hang glider pilots like to keep a landing area within glide, just in case.
Ultralight pilots forget about that because now they have a wonderful engine that hardly ever conks out, mostly.
What does that have to do with Quicksilver Project Design?
Well, you might want that 14:1 l/d but you probably won't get it using a flying wing airfoil on an unswept conventional wing.
Flying wings require more reflex and spanwise twist because they don't have a tail.
This screws up their l/d performance and there ain't no fix.
That's why there are no zero nada flying wings in sailplane competitions.
I was gonna wait to bring that one up but thought I'd better throw it in now if I'm about to disappear like I did from Paragliding Forum and OZ Report.

[Bill Cummings]

I understand that in the Blog Forum I may be removed if my posts to an individual blog is considered off topic by the blog creator.
I could still post to my own blog something that I feel is important to get out there to the pilot world.
When I start my own blog I can think of some pilots I've encountered on other websites that may not last too long on my blog.

Ground Slammer, you can be assured that there will be no hard feelings if you remove any of my posts on your blog for any reason or even if none is stated.
I have 900 flights in trikes. But like Rick warned I never put myself out of easy glide of a safe LZ in the event of losing power.
My instructor was, "Ole" (John Olson).
Early on in my lessons I asked Ole if he had ever lost power and was forced to land. His list was long and frightening.
(These accounts can be found in his "Wild Blue Yonder," publications.)

Hello Friends,

I just got a very nice message from Ground Slammer asking if he might be posting in the wrong forum.

According to our conventions, the Blog Forum has been open to all flying-related topics. A quick check of the topics will show that we allow discussions of all kinds of flying contraptions.

Also, the Blog Forum is a place where the Blogger (person starting a topic) should be able to control the content and flow of the discussion. I honor the requests of any Blogger to remove any posts in their Blog topic that they want removed.

Technically, the person starting a Blog topic should spell out the kinds of participation they want (or don't want) in the opening post of their topic. The default has "officially" been that others shouldn't post to a blog unless invited in the first post. We haven't really been following those conventions and I know that I've posted to Blog topics without being explicitly invited.

In this case, discussion was invited about a design, and some of the comments (including my own) have strayed a bit from the design discussion.

So let me accept the blame for being a bit too casual about enforcing our rules. So far, it's worked out pretty well, but maybe it's worth revisiting our procedures.

Ground Slammer, it's your Blog, and you're the one to make the final decisions. I officially apologize for my participation in making posts that may have been inconsistent with your intentions in this Blog. Please let me know what you'd like me to do to fix it. I can remove any posts that you want removed. They will get moved to the special "Removed Posts" topic. You're also welcome to start another blog by duplicating your first post and we'll try to do a better job of staying on topic. Or we can continue forward from here with a few "lessons learned" (my reccommendation). It's up to you. Feel free to call me if you want to discuss it.

I'm sorry for any inconvenience.

[Ground Slammer]

First today I would like to outline what I would like to see in this Blog.
For 50 years hang gliding has been suffering a protracted dark ages. The first dark age started in the 1930's when hang gliding was banned by the German glider clubs followed by the world. This dark age ended with the 1971 Lilienthal meet. A second dark age came about due to crashes with the Cronk Kite. The result was a ban on all rogallos except "Standard Rogallos" considered by many to be the prototype of the unsafe hang glider. Yet this was all we were allowed! For our own safety! The worst was the 3rd, now more than 43 years long, the ban on home crafted gliders. I was notified one day after the decision was made by the HGMA. No more kits, no more home made , if you can't launch with out an assist forget it ( amazingly if it's a rogallo and windy it's quite alright to have three people wire you but no one is to assist a fixed wing!) Today The EAA has an Ultralight Hall of Fame, but still to this day there is no EAA Hang Glider Hall of Fame. Hang Gliding has not allowed home building, and we don't merit any hall of fame, because of those who have succeed in killing the hang glider inventor/craftsman. It should be noted that it was the manufactures who banned the home built hang glider $$$. Hang Gliding does not merit a place in The EAA sub halls of fame because there has been no contributions to aircraft and flight science by the hang gliding home built community for 43 years now.

If you are a supporter of keeping hang gliding in the Dark Ages take it somewhere where it is welcome, because it's not welcome here

Some believe that for hang gliding to accommodate home building it would need to create an EAA like infrastructure-if this is more your interest hop aboard! First thing would be peer review-so my fellow hang gliding enthusiasts( my peers) let me spend some time on the airfoil I'm planning on for your review.

The Quicksilver's original airfoil was so profile drag dominate that the aspect ratio difference of the QS B and QS C did not matter . One can raise the aspect ratio but it still gets the profile drag indicated 7 to 1. We have many better options. First the airfoil must be compatible with the membrane and batten wing. Second it must be high lift at low speed and low profile drag. Last it would be helpful if it was stall resistant. 4 airfoils come to mind-Alpine, Fledge 2 (Benedek B-6407-E mod) the Fledge 3, and the Kasper (NACA8-H-12 mod). If I had to make a single surface wing it would be The NACA8-H-12 that Kasper used. For a double surface I like the low speed characteristics of The Fledge 2 over the Alpine. I also feel that for batten installation, and good high speed without the need for 80% double surface I like the Fledge 2 over the 3.
Fledge 2 suffered from tip stall but it was due to flattening out the airfoil as it approached the tip. This came with high profile drag outboard and more induced drag as well. So my build will rum the airfoil 100% to the tip and then make use of wing tip enhancements.

Airfoil.jpeg (116.54 KiB) Viewed 5571 times

In the top sketch I have given the geometric formula for the airfoil. In the middle sketch is a wing cross section at a compression strut. The lower drawing shows on top, the current state of the art in trailing edge, and below my up grade. Note the sever ramp on top, and on the bottom the mild tapper that leads into the trailing edge spar. To the rear of the spar on the bottom is an aluminum H channel section with a 3/8ths inch tube of aircraft aluminum stringer.

The H channel makes an excellent saddle on the 1 and1/8th inch rear spar as well as the 3/8ths. Note the low refractory angle past the rear spar in the tapper out. The 3/8ths radius is large enough to reduces chaffing of the fabric that a sharper edge would create. I hope to see the trailing edge modification create a TE as clean as the Fledge's. I'll know if the L/D hits 14 to 1.
The ribs or battens are planned on being the old fashion two piece wood type. They are wide, and flat on top not tubular.

The slack in the batten pockets will be on the underside only, thus making a flat plane on the top of the upper surface instead of ridges and sags. The main engineering questions here are: Will the wood battens insert readily, how to secure the batten, can I get away with more than 50% double surface, due to the holes in the pockets will I have ram inflation issues, or rip and tear issues. Note in the middle sketch, as one increase the amount of double surface the opening in the front pocket for the escape of the compression strut becomes longer and longer- what are the limits and will ballooning or strain become an issue? I'll be building a full scale wing section to help answer these questions and more. Well I'm going to stop here-I think I've used up my attachment allowance and this post is long enough. More latter.

[Ground Slammer]

Right now I would like to respond to Mr. Masters. Rick I too have lost a few friends over the years-none of them died paragliding or ultralight piloting they all died in hang gliders. You like to fly The Owens. My first trip to The Owens was just to go on a long motor home drive. As I got pass China lake I saw a dust devil- it made contact with a pump house made of 4x4 corners and 2x4 studs, corrugated galvanized siding and a solid door. The pump house was ripped off it's foundation- spun over 200 feet vertical, ripped apart-then it started raining hunks and chunks of building out of a clear blue sky. I had to make a run for my rig and run for my life. As I talked to locals they told me that that particular dust devil was not a note worthy one for "around here". This is the "safe " place you fly, and the sky that rains whole buildings is were you land.
As for reflexed airfoils in a straight wing tail equipped Quicksilver, I recommend that you do a little research first before you commit to posting. The first reported attempt to put a flying wing reflexed airfoil in a Quicksilver (Ground Skimmer Magazine-The Quickarus ) was a smashing success-look it up. Look up too that the NACA8-H-12 is not a flying wing section, it is a helicopter blade! Yes good thing Kasper didn't listen to you! You can't put just any airfoil in a flying wing- but you can put any successful flying wing section into a tail stabilized aircraft of equal cord and wing loading. Please note that the airfoil that I am attempting is unreflexed- as I stated it is the Fledgling 2 B root section. Rick the Fledge2 root section is unreflexed- you shot this one off without doing your home work. If you had done your home work you would not make such a foolish statement as the ones that indicate that you can't put a swept flying wing reflexed airfoil in a tail dragger-that's just plain unqualified, ad lib, bulls**t and I'd like my readers to know it.
All my friends who died flying stuck to hang gliding till it killed them.
PS-Larry Tudor "ain't" dead. Sorry if this seems hostile, but your making posts and you don't know what your talking about-just ask Larry Tudor

I was a professional stand up comic and sometimes you just have to shoot a heckler down.
Sorry Rick but sometimes I have to stand my ground.

Moderator's Note: In a subsequent post, the author corrected:

       "NACA-H-12 is actually NACA8-H-12".