Vans RV-G glider

[Mark James Boyd]

Hmmm....

I was wondering if metal gliders have an L/D disadvantage
due to the metal, or because of the lousy rivets and
poor wing airfoil and draggy struts (of the SGS gliders,
for example).

Is it possible to make a retract gear metal glider with
flush rivets and a carry-through spar which would give
40:1 ratio, or is metal just a substance that won't
allow the shapes or fine tolerances needed to make such
a wing?

Vans seems to do an excellent job selling very high
quality kits with very nice wings (metal). I wonder
if they'd consider selling a Quickbuild glider kit?

[John Giddy]

"Mark James Boyd" > wrote in message
news:3fa6166d@darkstar...
| Hmmm....
|
| I was wondering if metal gliders have an L/D disadvantage
| due to the metal, or because of the lousy rivets and
| poor wing airfoil and draggy struts (of the SGS gliders,
| for example).
|
| Is it possible to make a retract gear metal glider with
| flush rivets and a carry-through spar which would give
| 40:1 ratio, or is metal just a substance that won't
| allow the shapes or fine tolerances needed to make such
| a wing?
|
| Vans seems to do an excellent job selling very high
| quality kits with very nice wings (metal). I wonder
| if they'd consider selling a Quickbuild glider kit?

I believe there is a glider in the mind of their designer,
but there are other projects to be completed first
My memory (likely to be faulty !) tells me it was to be the
RV11.
Cheers, John G.

[Bert Willing]

My Caproni A21S Calif is an all-metal side-by-side twoseater. Finish is in a
way that you don't see any rivets, L/D is 41.5.

You pay an additional 10% of strucrural weight increase for having it in
metal (comparison to a janus C model - about the same wing span, the same
airfoil and pretty exactly the same polar). In a serial production, the cost
of a Calif is *way* higher than the cost of a Janus (that's why Calif's are
no longer in production).

If you want higher performance, it would mean more aspect ratio and less
airfoil thickness - and then metal would get really heavy.

--
Bert Willing

ASW20 "TW"


"Mark James Boyd" > a écrit dans le message de
news:3fa6166d@darkstar...
> Hmmm....
>
> I was wondering if metal gliders have an L/D disadvantage
> due to the metal, or because of the lousy rivets and
> poor wing airfoil and draggy struts (of the SGS gliders,
> for example).
>
> Is it possible to make a retract gear metal glider with
> flush rivets and a carry-through spar which would give
> 40:1 ratio, or is metal just a substance that won't
> allow the shapes or fine tolerances needed to make such
> a wing?
>
> Vans seems to do an excellent job selling very high
> quality kits with very nice wings (metal). I wonder
> if they'd consider selling a Quickbuild glider kit?

[Steve Beaver]

See: http://www.soaridaho.com/Schreder/


"Mark James Boyd" > wrote in message
news:3fa6166d@darkstar...
> Hmmm....
>
> I was wondering if metal gliders have an L/D disadvantage
> due to the metal, or because of the lousy rivets and
> poor wing airfoil and draggy struts (of the SGS gliders,
> for example).
>
> Is it possible to make a retract gear metal glider with
> flush rivets and a carry-through spar which would give
> 40:1 ratio, or is metal just a substance that won't
> allow the shapes or fine tolerances needed to make such
> a wing?
>
> Vans seems to do an excellent job selling very high
> quality kits with very nice wings (metal). I wonder
> if they'd consider selling a Quickbuild glider kit?

[Kirk Stant]

(Mark James Boyd) wrote in message news:<3fa6166d@darkstar>...
> Hmmm....
>
> I was wondering if metal gliders have an L/D disadvantage
> due to the metal, or because of the lousy rivets and
> poor wing airfoil and draggy struts (of the SGS gliders,
> for example).

Mark,

Depends what you mean by an L/D disadvantage. If all you care about
is max L/D, then sure you can make a metal (or wood) glider with a low
min sink and good L/D max. But if you want high performance at higher
speeds, then metal and wood start to show their disadvantages. If you
are willing to spend a LOT of time maintaining the wing surface
(filler, etc) then metal used to be competitive (see all the HPs,
etc). But Schweizer tried to compete with glass with the 1-35 (and
partially so with the 1-34) and failed - there is just no way to
economically get and maintain the laminar flow necessary.

During the 60s there were lots of attempts to make competitive metal
high performance (home-built, mainly) gliders, with mixed success.
Read Moffat's "Winning on the Wind"; he does some great comparisons -
an even thought that a combination glass/metal construction would be
optimum. But time seems to have proven him wrong, at least at
present, and at least at the upper end of the performance spectrum.

Now, for a fun to fly, sports class level glider, metal has it's
advantages, obvioulsly - as all those Blaniks prove!

And there is no way any metal plane is going to feel as nice to the
touch as a glass one, IMHO!

Kirk
LS6 driver and 2-32 fan

[JJ Sinclair]

John wrote>>>>>>>>>>>.>
>I believe there is a glider in the mind of their designer,
>but there are other projects to be completed first
>My memory (likely to be faulty !) tells me it was to be the
>RV11.

Van flies a Ventus 2M, maybe he is conducting research?
JJ Sinclair

[Bob Kuykendall]

Earlier, (Mark James Boyd) wrote:

> Is it possible to make a retract gear metal glider with
> flush rivets and a carry-through spar which would give
> 40:1 ratio...?

Yes. All it takes is good attention to detail during construction. And
after that, it takes microballoon mix, primer, paint, and lots of
sandpaper and elbow grease, reapplied biennially or as necessary. The
old Sierra Press soaring books are rife with takes of re-refilling all
the dings, rivet dimples, and seams in the old HPs, Prues, Schweizers,
and Laister ships. Been there, done that, got the bondo-smeared
T-shirt.

I remain firm in my conviction that the most cost-effective way to
achieve the smoothness and fidelity to contour required to get 40:1
glide ratios is with female-molded composites. Dick V. knows this from
his soaring contest experience. It's not the only way, and it's not
the best way for everybody or every situation. But where (quantity >
~3), it's pretty much the cheapest and least labor-intensive way.

It's why I'm spending a ton of money making full-size wing molds for
the HP-24 and its derivatives. I spent years messing around with
various sheetmetal and moldless composite schemes. And every path led
back towards female-molded composites in full-size molds. So I'm
making wing molds. Some say I've gone over to the dark side. But once
I finish the molds, these wing sets will darn near build themselves.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com/hp-24

[JDFlishall]

Why would anyone even consider building a metal glider when you can buy the all
composite Apis 13 or 15m kit with 400 hrs. build time. There is just no
reasonable way to duplicate the accuracy of a glass airfoil in metal. Were I
inclined to build a glider the Apis would be it.

JD

[BTIZ]

Laister LP-15 Nugget.. all metal wing, bonded like the Grumman's of old AA-5
etc.. no rivets showing.. reflex flaps.. SSA book says 36/1.. but it's old
technology..

BT


"Mark James Boyd" > wrote in message
news:3fa6166d@darkstar...
> Hmmm....
>
> I was wondering if metal gliders have an L/D disadvantage
> due to the metal, or because of the lousy rivets and
> poor wing airfoil and draggy struts (of the SGS gliders,
> for example).
>
> Is it possible to make a retract gear metal glider with
> flush rivets and a carry-through spar which would give
> 40:1 ratio, or is metal just a substance that won't
> allow the shapes or fine tolerances needed to make such
> a wing?
>
> Vans seems to do an excellent job selling very high
> quality kits with very nice wings (metal). I wonder
> if they'd consider selling a Quickbuild glider kit?

[Vince C]

The Peterson Javelin was built mostly out of metal and domed rivets.
The company carried out tests on the rivet shapes and reckoned there
was no difference between flush and domed. Furthemore they obtained
thier own 'cheap' rivets which they had FAI approved which saved them
a fortune.

The report can be found on the SSA website under the articles on
flight tests of various gliders.

Of course this relates to the 'then' technology, 'now' may be
completely different

[Kirk Stant]

(Vince C) wrote in message >...
> The Peterson Javelin was built mostly out of metal and domed rivets.
> The company carried out tests on the rivet shapes and reckoned there
> was no difference between flush and domed. Furthemore they obtained
> thier own 'cheap' rivets which they had FAI approved which saved them
> a fortune.
>
> The report can be found on the SSA website under the articles on
> flight tests of various gliders.
>
> Of course this relates to the 'then' technology, 'now' may be
> completely different


And as a result the Javelin was a medium-performance glider, with no
laminar flow over the wing. The design goal was low cost, not
performance (which explains the identical tail control surfaces and
spoiler roll control.

An interesting glider - I flew a brand new one once at the old
Vacaville gliderport back in the late 70s - OK performance but really
poor glidepath control and somewhat odd roll control. Sadly, the
following day it crashed (during a landing attempt, I think) and the
pilot was killed. I remember not being surprised by the accident,
which I think was a high pattern resulting in a low 360 attempt and
the classic stall/spin on final. Not a slam on the glider - it was
just different.

I cringe when I see gliders tied out for long periods - even poor
little 1-26s. At least hangar the little things! Especially now when
something like a PW-5 or Alpis can be rigged and ready to go in 30
minutes - clean, no bird droppings, no hangar rash, and with a really
detailed preflight inspection (at least that is how I treat my
assembly process..).

To me, a lot of the fun is the whole rig-tape-wash-setup
cockpit-pushover ritual that leads to a soaring flight. As long as it
isn't a Lak-12 or Nimnbus 3 - of course!

Kirk
Ls-6

[Tony Verhulst]

> one of the first jet bombers built in France, called
> Vautour, that was glued instead of riveted, don't know if there
> were other ones.

B-58 "Hustler"

Tony V.

[Graham Prophet]

Riveted or stuck, I guess, because you can't easily weld alloy sheet. It
would appear that now you can; I came across a reference to a biz-jet, the
Eclipse 500, that's built by something called friction stir welding. (google
'friction stir welded airframe' or 'Eclipse 500'). So I suppose in
principle you could now build an accurate alloy profile with a completely
smooth surface. Probably big-bucks for capital equipment and tooling so I
doubt if anyone will try building a glider with it, though. And it would
still take just the one hard push in ground handling - small dent - and
there goes your accurate profile.

Graham

"Tony Verhulst" > wrote in message
...
> > one of the first jet bombers built in France, called
> > Vautour, that was glued instead of riveted, don't know if there
> > were other ones.
>
> B-58 "Hustler"
>
> Tony V.
>

[Mark James Boyd]

>| Is it possible to make a retract gear metal glider with
>| flush rivets and a carry-through spar which would give
>| 40:1 ratio, or is metal just a substance that won't
>| allow the shapes or fine tolerances needed to make such
>| a wing?
>|

From talking to some other pilots, there seem to be other
disadvantages too: metal wings don't flex well so
rivets will pop on long wings with high load, constructing
long thin wings is much more challenging using metal,
construction time and creating the optimal wing shape
or more difficult with metal.

I think I brought this up because I've liked the 1-26 for
it's short wings (for landing out) and lack of struts and
the fact we can leave it out in the weather. Of course
it's glide ratio and high speed glide are poor, compared
to modern ships.

For me, because I weigh 150#, long heavy wings are not so
interesting. A Pegasus or PW-5 is really nice, but the
high speed polar could use some improvement (flaps?) and
even easier assembly would be cool.

The APIS FAI may be just the ticket for this. Very light
(so I imagine the wings are light for assembly), short
wingspan, and ailerflaps (flaplerlons?) are a great start.
I just wonder what the 80knot sink is with that draggy
wheel sticking out the bottom like the PW-5, and at
the lower weight with a 150# pilot...I haven't yet
found an APIS polar anywhere...

[Mark James Boyd]

In article >,
Martin Gregorie > wrote:
>On 6 Nov 2003 11:02:44 -0700, (Mark James Boyd)
>wrote:
>
>Failing that, look for an ASW-19B or an ASW-20. Both allegedly fly
>similarly to the Pegase and the '20 certainly has better performance.
>I'm looking at present. Pegase 90 would be my first choice, but as I
>may need NZ type approval I've got my eye on a nice '19B - that and
>several models of the '20 are already type approved.

I'm actually drooling over the Apis FAI. But between that and
a tiny baby girl on the way...I'll have to save up my gaga noises...

[Martin Gregorie]

On 6 Nov 2003 11:02:44 -0700, (Mark James Boyd)
wrote:

....snippage...

>For me, because I weigh 150#, long heavy wings are not so
>interesting. A Pegasus or PW-5 is really nice, but the
>high speed polar could use some improvement (flaps?) and
>even easier assembly would be cool.
>
If you like the Pegasus, and are thinking of buying, you should look
for a Pegasus 90. It is a more recent model than the 101 and all
self-connecting controls. The wings are fairly heavy, though. As an
additional bonus it reputedly has a bullet-proof gel coat.

Failing that, look for an ASW-19B or an ASW-20. Both allegedly fly
similarly to the Pegase and the '20 certainly has better performance.
I'm looking at present. Pegase 90 would be my first choice, but as I
may need NZ type approval I've got my eye on a nice '19B - that and
several models of the '20 are already type approved.


--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :

[Martin Gregorie]

On 6 Nov 2003 12:22:00 -0700, (Mark James Boyd)
wrote:

>In article >,
>Martin Gregorie > wrote:
>>On 6 Nov 2003 11:02:44 -0700, (Mark James Boyd)
>>wrote:
>>
>>Failing that, look for an ASW-19B or an ASW-20. Both allegedly fly
>>similarly to the Pegase and the '20 certainly has better performance.
>>I'm looking at present. Pegase 90 would be my first choice, but as I
>>may need NZ type approval I've got my eye on a nice '19B - that and
>>several models of the '20 are already type approved.
>
>I'm actually drooling over the Apis FAI. But between that and
>a tiny baby girl on the way...I'll have to save up my gaga noises...

I'd like a close look at one too. The performance and cost numbers are
both interesting. However, they seem to be pretty thin on the ground
outside Slovakia and the US. I like the idea of being able to work
weak energy lines, the more so as I've had a taste of doing just that
in an SZD Junior.

Do you know if they are ever likely to be stressed for and fitted with
a belly hook for winching?

I can't imagine ever owning a glider that could not be winched.

--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :