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Mar 21, 2012, 06:04 PM
VTPR & Slope Aerobatics
surfimp's Avatar
Thread OP
Build Log

ExCali - the California Excalibur VTPR Glider Project


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Update April 16th: First prototype has flown and it's great!

(3 min 17 sec)



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Five years ago today, I launched SlopeAerobatics.com with the goal of making it the best source of R/C slope and glider aerobatics content in the English language. Today the site features great slope aerobatics content from all over the world and helps bring us together so we can enjoy all that is going on. And there is quite a lot these days!!

So today, in celebration, I'm pleased to announce the latest collaboration between Swiss Peter and myself. We are undertaking our most ambitious project yet, a California reinterpretation of the world famous Excalibur VTPR glider from the mecca of voltige tres pres du relief: Bretagne, France.

Our glider will be named ExCali, which in Latin means From Cali and of course also pays tribute to the name of the original Excalibur designed by Eric Poulain.

We have been collaborating closely with Rémi Le Besque, the pilot of the red Excalibur 2 from the famous . Rémi is following in the long tradition of really cool French aerobatics pilots in generously sharing his time and enthusiasm with us as we undertake this project. Merci beaucoup, Rémi!

The ultimate objective is a 2.5m glider with molded fuselage and wood sheeted wings, the time honored construction technique of large and durable slope gliders worldwide.

Span: 2.5m
Length: 1.48m
Weight: ~1700g
Airfoils: TP42 - 9% (root), TP29 - 9% (tip)

Printable PDF of the ExCali fuselage shape: http://www.slopeaerobatics.com/excali_pdf.zip (10MB)
Costs about $5 to print out at your local Kinko's or equivalent.

The design will encompass best-of-breed features of the Excalibur 1 & 2, the Madslide, the Voltij, the Wasabi and the Le Fish. We intend it to be the most cutting edge VTPR glider produced up to this point, synthesizing all that has been learned in recent years about VTPR and Madflight.

Initially, so that we can have something ready to test and fly in time for the upcoming VTPR Demo at WeaselFest (April 14th & 15th at Ellwood Mesa here in Santa Barbara), we will be building ~2.0 - 2.5m EPP prototypes of the ExCali. We will use these prototypes to test ideas and then, when we are satisfied, we will proceed with mold production.

Next summer, August 2013, my family and I will travel to Finistère, Bretagne where we will spend a nice holiday on the coast. There I will introduce the ExCali to the locals at Ménez-Hom and fly it alongside the French pilots who have been such an important inspiration to us.
[Editor's note August 2019: I've visited Brittany twice now and met the guys, but still haven't finished the ExCali... ]

For now, I can offer only a teaser photo of the first fuselage cut... but watch this space, there is much, much more to come!!

Steve "Surfimp" Lange
SlopeAerobatics.com
Last edited by surfimp; Aug 29, 2019 at 12:46 AM.
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Mar 21, 2012, 06:07 PM
Wind Powered
george@dream-flight's Avatar
Boom!
Mar 21, 2012, 06:31 PM
Semper Fidelis
Big Gas's Avatar
Subbed.

Hopefully you'll be going with a TP42 or something similar that is symmetrical.

I'm leery of 2.5m in EPP. It's going to be heavy and floppy while requiring a lot of carbon to stiffen it up. I'd use EPS with carbon spars and new stuff. While not indestructible, it will make a great prototype.
Mar 21, 2012, 07:07 PM
VTPR & Slope Aerobatics
surfimp's Avatar
Thread OP
Just rememeber that we have the master of ultralightweight EPP building techniques on the job.. Swiss Peter!!

Really though, it's more that we've got a huge stack of EPP, a hotwire, and a bandsaw. Most important thing is just to build something. It can only get better

Steve
Mar 21, 2012, 07:45 PM
Registered User
prodjx's Avatar
BTW# speaking of Cali have you ever heard the song Calle by Joyce Cooling from the cd Keeping Cool might make a good sloping sound track.
Mar 21, 2012, 09:27 PM
Registered User
Snewk's Avatar
This is going to be one fascinating journey to follow! My hope is that it results in both the mouldie/sheeted wing aircraft you're envisioning and an all foam version that can be Swissed down to an ultralight wing loading. (and for us small slope types a 2.0 meter would be appreciated )

The classic high aspect-ratio lines of the Excalibur are a big factor in why it flies so gracefully. Hopefully a lightweight version would retain some of the energy retention ability of the original. As to John's concerns re. an EPP wing that length.....how about balsa sheeting covered with New Stuff?

Ken
Mar 21, 2012, 11:02 PM
vtpraerobatics.blogspot.c om
oldscooler's Avatar
...
Last edited by oldscooler; May 05, 2012 at 03:44 AM.
Mar 22, 2012, 11:29 AM
VTPR & Slope Aerobatics
surfimp's Avatar
Thread OP
Quote:
Originally Posted by Snewk
This is going to be one fascinating journey to follow! My hope is that it results in both the mouldie/sheeted wing aircraft you're envisioning and an all foam version that can be Swissed down to an ultralight wing loading. (and for us small slope types a 2.0 meter would be appreciated )
We will be following my standard operating procedure: there will be a plan released under the same Creative Commons license as my other designs, including a tiled PDF for printing and a DXF for cutting (I'm finally getting my head around CAD and the Le Fish plan is very close to done). This pays homage to the tradition of the Excalibur and Madslide, both of which were designed to be easy and inexpensive to build for a scratchbuilder, and which had plans published for public consumption.

I actually like the 2.0 meter size quite a lot for EPP (moreso than 2.5m for reasons noted above) and it's possible I'll do mine at that size. What I'm really trying to verify, at least in this first pass, is the influence of the Excalibur fuselage shape and planform when combined with what we've learned from the Madslide (full flying Madstab), Wasabi (airfoils) and Le Fish (straight leading edge wing).

Peter and I are going to be building slightly different versions of the plane, because it doesn't make a whole lot of sense to build two identical aircraft when you're trying to test a range of variables.

Steve
Mar 22, 2012, 12:07 PM
It's time for me to fly
JimZinVT's Avatar
This sounds great! I love watching these design/build threads unfold.

Re: material, once a plan is published, the builder can choose any material he likes. I've had great results with blue XPS covered with lam. film on smaller models, and I'm fairly certain with proper wing spars it would work at this span.

What I'd like is a 2-piece wing system (magnets!) for portability. I can't carry a 2.5m (or even 2m) wing in my cars.
Mar 22, 2012, 01:20 PM
Phil.T-tailer
Phil.Taylor's Avatar
Quote:
Originally Posted by surfimp
Next summer, August 2013, my family and I will travel to Finistère, Bretagne where we will spend a nice holiday on the coast. There I will introduce the ExCali to the locals at Ménez-Hom and fly it alongside the French pilots who have been such an important inspiration to us.
sounds like a plan for a French holiday next year - shame my wife doesnt like planes - she'll just have to stay home

good luck with the ExCali project - presuming its going to have a mad-AMT - then you can invent the "X-Scallywag" move with it

Phil.
Mar 22, 2012, 01:24 PM
VTPR & Slope Aerobatics
surfimp's Avatar
Thread OP
But surely she likes the beach? I know mine does.



Steve
Mar 23, 2012, 01:48 PM
Registered User
Snewk's Avatar
Been thinking too much......(again).......

Wondering about possible benefits of engineering/building the plane around the "innards" rather than first building the aircraft then figuring out how to stuff all the gear into it.

If a builder put together a "chassis", either a single longeron tube, vertical oriented flat sheet or "X"-form of CG tow or weave that ran the full length of the fuse he could then install battery, radio, servos, drive linkage and tail control mechanisms precisely and securely where they need to be. Doing so would allow testing and adjustments to be made until everything was perfect. Design flaws could be spotted and addressed a lot more easily than building the entire plane, test flying then tearing down and rebuilding. The next steps would involve hollowing out a pair of foam slabs to encase everything then shaping it down to the desired fuselage form, setting up the wing mounts etc. etc.

Like I said....."Been thinking too much........"

Ken
Mar 23, 2012, 02:07 PM
VTPR & Slope Aerobatics
surfimp's Avatar
Thread OP
Heh, yes the concept has been discussed before, specifically as regards testing different fuselage shapes to confirm optimal lateral area distribution.

That said, since the goal is an Excalibur-based plane - and since it's a quite well-proven design - we already know where the gear needs to go: as far forward as possible to minimize deadweight for balancing

Steve
Mar 23, 2012, 02:13 PM
VTPR & Slope Aerobatics
surfimp's Avatar
Thread OP
Oh, and I watched this again last night... such a great video. Rémi and Eric's flying is so smooth and graceful. Primarily it's straightforward aerobatics figures performed with grace and precision. They look like they're having a blast and it makes me want to be there, like, right now!!

(22 min 50 sec)


Yes, guys, somebody is out there, and we feel your vibration

Steve
Mar 23, 2012, 03:45 PM
Registered User
Snewk's Avatar
And then there's this one from Eric's blogspot collection.

What is that move at about 4:22???

http://vtpraerobatics.blogspot.com/2...ergne.html?m=0


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