[JoeF]

Earlier related:
=============
Teflon-bottomed surfaced skis or ceramic-bottomed skis versus wheels for HG?

What are the comparative mechanics involved?
Tangent contact vs broad-flat contact?
Bumpiness mitigation?
Gouging quotient of wheels versus skis?
What studies and experiences are available?
What tests might be designed?
Perhaps WWW or SWW (wheel when wanted or ski when wanted) capability?
Is there a bias for wheels that may not be well-founded over skis?
What landing textures are we to apply our considerations?
Drag comparisons?
Optimal designs of wheels and of skis?
What distance below basebar would be great (avoiding the catchiness of the basebar on grasses, shrubs, rocks, etc.
What have we?


[[Edit: SSSASS Safe-splat-shock-absorbing ski set]]
An earlier cousin thread: http://ozreport.com/forum/viewtopic.php?p=89148

=================
Peanuts noted:
Re: Teflon ski versus wheels for HG? Tue, Jun 12 2012, 8:13:46 am
not just distance below, but distance in front of base bar should be checked, to mitigate nose-overs.
=================
I noted:

Makani seems to have respected the content of your suggestion:

[JoeF]

More of the earlier: Tue, Jun 12 2012
Tony,
Did the A-frame-feet extension ski on your experiments have specific shock-absorbing arrangement, or was the ski-touch-impact force vertically without shock-absorbing "give" ? A common run of "wheels" on the feet of A-frame for HG gives a gouging sharp tangent point that far too often hardly mitigates face plants and whacks.

Did you have reason not to continue the use of the skis that are pictured in your early experiments?
ski shown:

TP22 Location:- Brasted
Preparing to launch

TP24 Location: Brasted
Skimming down the slope

Joe,
As you can see the skis were balanced to ride at a high angle and were free to pivot around the control bar which had considerable rake forward. First ground contact was at the rear of the ski which then flatened as the wing lost lift. There was no springing or shock-absorbing other than the give in the supporting brackets. I used them for initial wing trials on very shallow slopes which allowed for extended glides in ground effect. They also served a purpose when complete novices flew the wing before they mastered stand up landings. Once I was flying from higher slopes I dispenced with them as a full flare and no step landing was very easy on the splitwing glider. They also added weight and longer rigging time. The jib wing enabled high angles of attack at slow speed without loss of control.

Tony

Some miscellaneous thoughts upon reading your reply:
1. Thanks for the reply to the questions, ARP !
2. Optimized engineering and choice of materials along with care to produce the "give" wanted… might bring a new visiting of the tactic.
3. Following Peanuts' suggestion, the ski front might be positioned frontally to respect concerns.
4. Facing the bottom of the ski with choice material and reaching for best-fit broadness of the bottom face is open grounds for discovery.
5. Controlled ablative braking might be a combine that could be triggered out of the face of a ski.
6. Comparison of drag cost relative to wheels seems to be a space of research.
==================

[JoeF]

Continuing earlier matter:
Christopher noted
Teflon ski versus wheels for HG? Tue, Jun 12 2012, 8:50:10 pm
Thanks for including the correspondence, Joe. Do you have anything to report on the little skid-pods I've seen (mostly on ridgeds)?

=================

Thanks for including the correspondence, Joe. Do you have anything to report on the little skid-pods I've seen (mostly on ridgeds)?

Good lead, Christopher. Others are welcome to post clips of front-space whack-not mitigation structures
on any aircraft as a preamble for facing your question and for displaying a design solution pool.

I will be editing this post with the same target. Spoons, flat bills, skids, bulbous wheels, rollers, deployables,
frontal skis, etc. are invited. A tiny wheel can act as a sharp gouging penetrating spear when impacting
various ground structures and textures. An initial contact of a wheel is often an infinitesimal point where
friction is needed to get the wheel turning; yet one may still get stuck in sand and mud with a spinning wheel.
Spoon-faced skids, skids with arc fronts, wide rollers, etc. are options. Even a mono-wheeled-circumferenced HG
is being examined. Have a gooney-bird long neck that splats and slides?
For some early warming-up visuals, see the page: http://wright-brothers.org/History_Wing ... s/UFOs.htm
where there are some instances of A-frame, pilot behind A-frame, and anti-whack solutions.

Then for preliminary study:

To start at the moment, just a meditation over a clip from a Lazair:

Dave Stewart has copyright on http://historicaircraftpictures.com/blackburn-01.jpg

Notice that the A-frame down tubes seem to be deliberately non-straight,
perhaps to allow immediate "give" upon contact with the ground.
The pre-curve would allow arcs in the A-frame side legs to give a cushioning effect.

Notice that there are two types of A-frame in this glider. There are two inverted A-frames
that seem to integrate with the anti-whack nose-to-base while firming tie with the fuselage central-keel structure.
Then there is the Pilcher-like or Wenham-like A-frame that supplies kingpost
and double queenpost rigging points at the ends of its base bar.

LOWER PHOTO: Version Demoiselle (replica) BAPC.194 (photo, Nigel Roling/Pentavia):

In this early Otto wing there is barely seen the hoop structure.

Control so one does not whack: 1912 seat offer in catalog:

with pilot hanging behind control frame which is integrated with cockpit frame;
there is little-to-no anti-whack mitigation devices in his hang glider as he approached the design of his Albatross.

The nose-in mitigation seems to be a combination of the hull and wheels and controls.
Grade Doppelsitzer ~ Tweer, Hans Grade
_____________________ Gustav Tweer in rear; Hans Grade in front.

had a complex A-frame featuring two sets of two wheels as well as the foreward nose-in ski skids (two).
I am holding that the inverted catenary-curved basebar would be able to cushion landing loads.
Note also that the craft had a second A-frame to play kingpost-double-queenpost role.
This two-seater of 1914 had the two pilots up into keel fuselage unlike the Grade Doppelsitzer
where Tweer and Grade were suspended beneath the keel behind the A-frame (see above).

Others are invited to find and post for study any mitigation of the landing-nose-in challenge.
As aircraft found control mitigation for pitch in the landing sequence and gained confidence, then one sees
a devolution of the frontal solutions. The flying canards and the holding structures for them double roled
as nose-in mitigation; a canard aerodynamic control combined with mechanical skid solution is found in many craft.
The canard family can be edited into this thread as anyone finds good examples, not the least such in the Wright Brothers
experiments. The pitch-control direction of "High Hats"
has little following yet, and seems yet not to have been much explored; the bird tail for empennage guide
seems to have been dominant by far over the canard or the high-hat directions. Yet we are not done exploring for hang gliding.

Note this 1908 gliding-club hang glider has the very common A-frame that we still use today
cleaned up and modified mostly; the pilot was hung from the keel behind the A-frame down tubes or legs
while he grasped the base bar; the control frame was cable-stayed
and acting as two queenposts as is common to hang gliders most popular today.
The wing is resting on his shoulders while posing. Such basic triangle control frame stayed good for some purpose even while such
was morphed into thousands of versions of undercarriage for kites, gliders, and powered aircraft. The simplicity for pendulum weight-shift control
was not overlooked by the later decades of water-ski kiters and ski-kite-gliders as they could fall and nose in water without wheels; some
later added floating skidding pontoons; when on land: wheels and Prentice skis to the basebar and it extended. Wing runners and those
mitigating nose-ins, whacks, beaking, etc. are looking for mitigation (besides learning to fly well, so that there won't be a need for a mitigation!).
But unwanted pitch-ins occur and one may not want to be without a mitigation of the injuring forces. So, visiting the past and future
just may bring on some design solutions of interest. The No-More-Whack Club and the Wing Runners of WWRA have a keen interest
in Safe-Splat solutions. All are invited to play for advances. Share your ideas however yet unbaked they might be!
http://imechanica.org/node/5255

Gustav Tweer with "Grade" Eindecker (monoplane)
Note how the A-frame is basebar wheel for some mitigation. But notice also how the A-frame legs are let through smoothly to become kingpost players.

[JoeF]

Lostgriz had noted "QUACK" upon seeing the above image of the duck doing a safe-splat in the snow.
======================

QUACK!

Q.U.A.C.K. Bob Lovejoy's Quite Unusual American Canard Kite comes to mind with your emphasis, Lostgriz. Thanks. Bob and I high jumped together. He came into hang gliding while he was working at Mattel Toys; he then worked at hang glider manufacturer Eipper-Formance. His end in an ultralight part challenge was sad deeply. My son flew in Bob's first hand glider wing; my wife flew the first Quicksilver. Bob's Quicksilver and its following ultralight use became a huge success story; he won EAA Hall of Fame eternal position. His QUACK hang glider with its canard fits this topic thread. All are invited to bring up for study the canards and possible double-roles as flight control and nose-in mechanical mitigation.

Q.U.A.C.K. Bob Lovejoy's Quite Unuusal American Canard Kite pictured in Popular Science, May, 1974 was a proper kite and proper paraglider and proper hang glider, as it was a gliding kite. Caption of photograph in 1974 issue of Popular Science: "Quicksilver to Q.U.A.C.K. --Bob Lovejoy rearranged the former's parts to create his "Quite Unusual American Canard Kite."" Horizontal stabilizer is up front, rudder is on top, wing has fixed leading and trailing edges, but no ribs." http://tinyurl.com/QUACKbyLovejoy
In the photo at the PS article, Bob is flying his other kewl wing HighTailer.
In the QUACK photo, Bob is in the right of photo standing with white shirt and white hat (hard to see hat).

Was Bob inspired by the Wright Brothers' kiting and canard?

Lostgriz, your synergy has let the following to be found for my first time in all these years:
Flight was on Bob's mind in many ways.

======================================

Note the combine of frontal bulbous wheel with large curved skids as well as a flying canard control.

=============================

=============================

Notice that the pilot is actually hanging from the upper wing; notice that the triangle has infinite zenith point approximately for the two downtubes; the hanging is via a complex of sticks and wires. The frontal canard is for control; the holders mitigate nose-in.

========================

[JoeF]

Vanilla on Grass


SkyDogSports
Bob Grant

[JoeF]

ShockWheel

[JoeF]

Floyd Fronius
GOAT

FloydFroniusGOAT.JPG (22.41 KiB) Viewed 5606 times

[JoeF]

EMG

EMG.jpg (39.52 KiB) Viewed 5603 times

[JoeF]

Deliberate Land-Launch for Lake Landing
Topic hereon is intended for mild water states, not open ocean, though some of the exploration may apply to ocean "landing".
D4L
The statements hereon are rough conceptualizing notes: (feel free to continue the theme of launching deliberately from land while deliberately concluding hang glider flight on lake surface)

Choices:
== No pontoons. Sealed hang glider that floats. Morph rig after landing to sailboat status.
====== Drop out of HG before "landing"
====== or have a system where skiing and mild sink are safely acceptable.
====== or have system well tolerate flare or parachutal
== Pontoons: Hidden deflated pontoons at launch. Inflate pontoons before "landing" on lake surface.
== Pontoons: Open pontoons fixed at launch.
== Coordinate with lank ranger or manager as to the launching of the sailboat-hang glider. Avoid unneeded "rescue" by having good open communications.
== Perfect the mechanics before going public.
== Stay in wind and water states that match the system for safety.
== Have HG be water tolerant.
== Post lake surfacing: Morph rig to be a sailboat.
== Aim to be without need of assist boats and without need of "rescue" operations. Aim to have activity fully safe and eventually a clear option for sport hang gliding.
== Post lake surfacing: Wade the rig to shore, if the location fits such operation.
== Valved ram-air inflatable pontoons when wanted (air does enter but does not exit; may be deliberately deflated) (also positive inflation could be by several methods). Landing-drogue ram-air inflation would be an option for pontoon inflating.

[Bob Kuczewski]

We've been having a lot of fun at Dockweiler. Maybe it's time to get to work on your safe splat project there. Just let me know how I can help.