RE: An MK 20 Size Conservation Project
 

Further advances. I hope to have the fuse plan finished in a week or so and then I'll go over it in detail prior to laying out parts.

I should have some further updates on the Aurora in a few days as well.

With the design gods willing, we may actually have wood under the laser by Xmas!

David.

RE: An MK 20 Size Conservation Project
 

I thought I'd update this thread with some really cool stuff!

Moving right along now...

David.

RE: An MK 20 Size Conservation Project
 

Hey ,
that looks kind of familiar ;)

RE: An MK 20 Size Conservation Project
 

Rumours on German forums say Webra got bancrupt :-(

RE: An MK 20 Size Conservation Project
 

Hi Viktor,

good to hear from you. I sent you a line by email a few weeks ago - hope you got it. Let me know if you didn't. I sent it to both your addresses.

That is some sad news about Webra. Are they rumors or is it a known fact now? I'm not sure how Webra is doing in Europe but I have to say that it is rather tricky to buy them this side of the pond. There hasn't been a good distribution channel for some time - something that is keeping both OS and ST in good shape. Not that ST is the same company as it used to be. Honestly with the popularity of gas and electric these days, I'd imagine that all engine manufacturers might be in dire straits.

Happy holidays to you and family!

David.

P.S. I just recently acquired two vintage Webra engines - a 61 RE and an 80 SE. Unfortunately this won't help their cause.

RE: An MK 20 Size Conservation Project
 

Years back, Cliff Swartz in Winnipeg was the North American distributor for Webra Engines. But Cliff passed away a few years ago.

Even though some people have gone electric. I can't justify the expense of a 80-100 amp bec and lipo batteries to fly a 40+ size plane, when a 40 engine can be purchased between $75~$150.00 (depending on the manufacturer). I like being able to land and fuel up right away again.

Jim

RE: An MK 20 Size Conservation Project
 

<font size="4">I like the smell of castor oil in the morning...</font>
<font size="4">and I like Webra engines</font>

RE: An MK 20 Size Conservation Project
 

Well,

it's official:

http://www.webraengines.com/index1.html

Sad news.

Unfortunately, the closing statement not only was very poorly scripted but also very poorly translated into English. This never bodes well, even at the end of the line.

David

RE: An MK 20 Size Conservation Project
 

I can swap out my battery pack quicker than you can pump 16 oz into your tank and flip your prop :) And I can do it on the runway without carrying a Ni-Starter!

Andy

RE: An MK 20 Size Conservation Project
 

:D:D:D That's true Andy , I still like nitro smell from time to time.

RE: An MK 20 Size Conservation Project
 

It's a 40 size plane. 10 oz tank at the most. I can fill it up at half the time of a 16 oz tank. http://www.rcuniverse.com/forum/js/f...n/rolleyes.gif

Jim

RE: An MK 20 Size Conservation Project
 

So do I, Rafa! Especially when I'm not paying for it :)

Andy

RE: An MK 20 Size Conservation Project
 

Now that we've worked out the nitro vs electron debate - let me comment that the good news is that these MK design models will be suitable for both electric and glow applications. The Aurora 30 will be especially well suited to electric power while other classics such as the Curare and Skymaster will be suited for either. Of course, some classics such as the Arrow are especially well suited to glow power with a RE engine.

David.

RE: An MK 20 Size Conservation Project
 

That's the way you enjoy it most !!! :D:D:D

RE: An MK 20 Size Conservation Project
 

I love my 1.20 size webra such a speed demon!

RE: An MK 20 Size Conservation Project
 

<font size="4">webra's site is not available anymore...</font>

RE: An MK 20 Size Conservation Project
 

They recently posted notices that they were bankrupt . There are no plans to return to business.

Too bad. I even liked the Dynamix carb.

The gas and electrics have largely replaced their offerings, though not in the minds of those of us who flew them for many years.

See post #133 above.

RE: An MK 20 Size Conservation Project
 

David,

I still have a perfect Curare 20 with an OS 25 flying like a dream. Unfortunately the plan was cut up and the kit partly built when I bought it over. I would be very happy to find scans of the Cosmos, Curare and Aurora 20. Did you copy them already ?

Here a copy of an golden oldie: the Mosquito from Graupner, to show that it really works well with the plan scanner.

Michel

RE: An MK 20 Size Conservation Project
 

Hmmm ... disregard. It was late in the evening and I did not see the thread had been developed so far. I also sent the wrong files.

Indeed, the Curare airfoil is a NACA 63A with the max thickness taken back to 30 %. I made foam templates and have cut a wing for a friend.

RE: An MK 20 Size Conservation Project
 

Michel,

thanks for your interest in the conservation project. I was about to send you a PM but I see that you've had a chance to read the thread.

We have been on a temporary hiatus in progress on the project due to personal reasons but expect to resume in the near future.

Thanks also for the info regarding the Curare airfoil - something that we were interested in finding out but hadn't looked further into it. Do you know if the max thickness remains constant at 30% across the span of the wing? Or does it transition in its chord position?

Indeed it would be interesting to know what airfoils Prettner used on all 8 of his designs as well as the airfoils chosen by the Japanese (Yoshioka, Kato, Naruke, Akiba, etc.) on their designs.

Please post some pictures of your Curare 20 if you have some.

David.

RE: An MK 20 Size Conservation Project
 

???

Did your plans for the Curare, Cosmos and Aurora get damged? I'm sure someone here can fix any problems that may have occured.


DM

RE: An MK 20 Size Conservation Project
 

David,

I don't think Michel has those models - he has a C20 which would be nice to see pictures of. Michel?

As far as the Cosmos and Aurora, we're working on that so that all can have slick 30 size machines! Hopefully we'll pick up the work on the Aurora again soon which had to be put on hold for a while.

How about that SM20 David?

David.

RE: An MK 20 Size Conservation Project
 

Sorry about that, I just read the post again. I was pretty tired last night and misunderstood that. :eek:
The Skymaster is on hold until after my big move later this year. I'm really excited about having some room to build... and an actual airfield to fly again. :D


DM

RE: An MK 20 Size Conservation Project
 

Hi fellas I was given this kit the other day by a friend who knew I flew RC planes.It is complete except for plan and instructions.I have nutted out most of it but stuck with where some of the parts go.The quality is high and I like how he has designed everything.I have enjoyed this forum and have become very intersted in these pattern planes.[img][/img]

RE: An MK 20 Size Conservation Project
 

Folks,

while it might seem that this project is dormant, there has been some progress lately. I have been told that progress on the Curare 20 and Aurora 30 will resume soon. Given the advanced state of both, it would be very nice to see these two projects come to completion.

For my part I have been making some progress on both the Skymaster and Blue Angel. I was fortunate to purchase a glass/foam reproduction of the BA20 which was molded and cut using the MK BA20 kit as a plug. Dimensions and planform match that model to a T. Unfortunately the vertical which is molded into the glass fuse is warped (perhaps due to long term storage) so I plan to replace it with a built up wood version. I'm also thinking of replacing the design of it from the BA20 design to the scaled down BA60 design which I find is more graceful. The idea with that fuse and wings was to produce a glass/foam kit for those who'd rather build a kit like that than the traditional all wood MK kit.

In the process of designing that fin, the rest of the CAD design of the BA20 came together but rather than reproduce the BA20 MK kit, I decided to continue and produce a scaled down BA60 MK kit. The result is a larger BA30 model with a 52" wing span intended for .28 to .35 size engines with the OS and Webra SE .32's specifically in mind. Design of this model is per the full scale but wood thickness and material has been adjusted to produce a reasonably light 30 size model. The front of the model has also been slightly adjusted to provide adequate space for a 30 size nose gear (again, electric retracts are planned here) as well as a 2" spinner. The scaled down model results in a slightly smaller spinner and the retract bay is somewhat restricted to accommodate a 1-3/4" nose wheel. I think you might be hard pressed to tell this modification as the lines have been preserved quite well. Space for a 6" oz fuel tank is also ample. Hayes slim line tanks might be ideal here.

Th reduced scale approach is the same as that which was adopted for the Aurora 30 which will be better suited for electric power (unless some folks want to produce and use a swan neck header or happen to have a 32 sized RE engine such as the new Enya's. An alternative, albeit somewhat heavy, would be something like an OS 40 VF). I think that both the BA30 and the A30 will result in very attractive 30 size classics.

Below is a taste of the plans and the work thus far. Formers are done, wing and stab ribs remain to be drafted. Fin structure (i.e., ribs) is also a little tricky. The cool fin fairing and stab top block of the full size BA60 will be reproduced in "side block form" by cutting it to fuse side template and using two blocks with a 1/32" ply center keel to preserve the fuse centerline reference shape. This approach is not like a CNC routed MK type block but is close enough and easier to build with than one might otherwise if scratch building (as Mike did with his BA60 and Jeff did with his Aurora 60).

David.