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Old Dec 26, 2013, 11:36 AM
glattCAD Flugmodelle
chris-67's Avatar
Germany, BY, Langweid am Lech
Joined Dec 2004
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Heinkel He 162 Salamander 4th scale (90" x 70")

Hello,

quite a long time that I posted here last time, so I´d like to shortly (re)introduce myself. I´m Christoph Glatt, live in Southern Germany. Occupationally I assess specifications and safety cases for railway systems. But what I really love to do is design 3D model aircraft. Usually I start with 3-view plans, vectorize and import them into Rhino 5, the software I mainly use. I do the fluid dynamics calculation and after a few hours this results in what you can see on the pics below.

I just finished the CAD work for my latest project,

Heinkel He 162, quarter scale, length 2.28m (90"), span 1.78m (70").

As the original my model will also be a classical wood construction. Click here for a phantastic 360° pan of the He 162´s cockpit. The prototype is intended to be powered by a Vasafan 120 mm, 14 blades using 12s lipo.
In the moment my cnc mill is out of order because a new high freq spindle is to be installed, hopefully tomorrow. So the new year will start by milling 3.8 m2 (4.5 yd2) of poplar plywood, 1.25 m2 (1.5 yd2) of balsa and 0.35 m2 (0.4 yd2) of fibre glass boards.

On my latest model - D.H. 88 Comet (5th scale) - I posted the whole construction progress on the German RC-Network.de forum. This time here on RCGroups!

Please ask if you´re interested and feel free to suggest improvements, but excuse my doubtful English, I try my best! I´m looking forward to your response. Have a look on my website glattCAD.com, too.

Regards,
Christoph.
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Last edited by chris-67; Dec 26, 2013 at 11:38 AM. Reason: typo
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Old Dec 26, 2013, 11:51 AM
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United States, IL, Northbrook
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Amazing work! I like your DO-335 model on your website too.
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Old Dec 26, 2013, 02:43 PM
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Antwerp, Belgium
Joined Sep 2004
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Amazing Chris.
Looking forward to seeing the build!

Frank
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Old Dec 26, 2013, 04:20 PM
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eatond's Avatar
United States, MO, St Charles
Joined Nov 2002
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Hi Chris,
Nice work, I'm looking forward to watching this build. I also checked out your D.H. 88 Comet and will have to spend some time there reading the complete thread.

This may be just an effect of the angle the pictures were grabed at but compared to the rest of the wing structure the wing spar looks pretty massive and there's two of them. Could you please elaborate on the design choice if it wasn't a picture effect?

Dan Eaton
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Last edited by eatond; Dec 27, 2013 at 11:43 AM.
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Old Dec 27, 2013, 03:54 AM
glattCAD Flugmodelle
chris-67's Avatar
Germany, BY, Langweid am Lech
Joined Dec 2004
107 Posts
Hi all,

thanks for the kind words!

Dan, you´re right, the spars look quite massive, but they aren´t really too massive. Most of it is air inside. The pine bars (3 mm x 10 mm) lie horizontally so that - together with the hard-balsa elements - the He 162 will get two boxed wing spars. At speeds of more than 160 mph the size of the boxes seem to be correct and safe to me. Designing them with their maximum of cross-section area results in maximum box stiffness.
Two seemed to be reasonable, because of the thin airfoil a single plug-in mount with sufficient diameter (is that the correct English expression for these tubes?) would not have been possible. It simply would have been too weak. So two tubes needed to be implemented thus distributing the wing forces to the fuselage best. Another reason for using two spar boxes are torsion aspects, so the wing torsion along the span will be minimized.

Christoph.

By the way, a summary of the "D.H 88 Comet story" is on my website glattCAD.com, the RC Network thread may be too long in deed, and in German ...
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Last edited by chris-67; Dec 27, 2013 at 04:00 AM. Reason: additional sentence
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Old Dec 27, 2013, 04:45 AM
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Colchester UK
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Christophe

Very nice computer work, and great use of CNC milling. I am amazed that so many in Germany seem to have the abilities to do the design work and also build their models largely from balsa and ply. I love it and really appreciate all the hard work. I too love scratch building.

John
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Old Dec 29, 2013, 03:56 AM
glattCAD Flugmodelle
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Germany, BY, Langweid am Lech
Joined Dec 2004
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Hi Dan,

maybe my post to your suggestion was a bit too "straightforward". Sorry! By experience, at least mine, when designing on the computer it is rather difficult to unerringly find the smallest reasonable gauge or cross-section for a spar or bulkhead before having built anything. After the prototype´s build and its first flight season one always knows better.
I already concerned myself with FEM analysis to find more precise predictions and assumptions. The problem is to get verified and credible input data and basic conditions for the analysis, so I cancelled the approach quite early. Dan, I would very much appreciate your contribution to this thread.
I´m still busy trying to fix the last problems with my mill ...


Greetings and a happy new year!

Christoph.
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Old Dec 29, 2013, 03:15 PM
Build'em and Crash'em
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Narragansett, RI
Joined Oct 2000
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Chris

I had a 55" Midwest HE-162 on a 90mm midi fan
http://www.rcgroups.com/forums/showthread.php?t=926890

A couple of lessons learned from that design
Battery needed to go all the way forward along with the Rx to get the CG right. And my fan was not as far back as your design. I did not have a nose gear. You may want to do some quick weight and balance calcs to guide you.

The Midwest 162 would glide forever. I had a power out on one flight and almost overshot the runway as it would not slow down. Really consider flaps to help it slow down.

The cockpit takes up alot of room in the nose if you want a pilot in there. This takes away space for any packs, or moves them backwards, which makes getting the CG right harder. The round fuse makes finding room for square packs harder than you would think. Dont forget about pack access too. I see in the drawing what looks like 2 packs, but its hard to tell if thats really scaled for what is probably a 12S 5000+ pack size.

When you fly it be aware that it looks a bit weird in the air due to the way the wingtips hang down. It takes some getting used to as you bank it for those turns. Sounds strange but when you fly it you will understand.

Unfortunately I lost mine on the only bad bungee launch I have ever had

looks like a great project, good luck
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Old Dec 29, 2013, 06:11 PM
glattCAD Flugmodelle
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Germany, BY, Langweid am Lech
Joined Dec 2004
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Hi Ken,

thank you for your very helpful advice!
Keeping the CG to the position I was calculating (I mean the aerodynamic calc´s) was challenging in deed. Have a close look at the screenshots attached. The first shows the position of a fat 12s 8000mAh battery pack in its most forward position. The second one shows the battery "tray" fixed in its last possible position, 84mm behind. The third shows how to put the pack in and out. No problem so far - hopefully ! It should actually be possible to stick a 14s inside!
Although having calculated the CG considering nearly all the model´s masses in the CAD I still feel uncomfortable: I did not take the planking and finish (color) into account. Practice will show us soon!

This "Volksjaeger" will get flaps of course! There is no reason to do without them.
Do you intend to build up another one after the loss?

Chris.
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Old Dec 30, 2013, 11:36 AM
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Joined Nov 2002
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Quote:
maybe my post to your suggestion was a bit too "straightforward".
Hi Chris,
No worries. I appreciated you taking the time to explain your design choices. I'm looking forward to seeing more of this plane in the new year.

Happy Hollidays,

Dan Eaton
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Old Dec 31, 2013, 08:45 AM
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Brisbane, Australia
Joined Oct 2004
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Hi Chris,

Great project!!! I love the volksjager!

Another question, the wings look like they have some forward sweep? The two main spars in the wing do look a little overkill to me as well.

What drawings did you use to draw it up?

Thanks

Dave
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Old Dec 31, 2013, 10:46 AM
glattCAD Flugmodelle
chris-67's Avatar
Germany, BY, Langweid am Lech
Joined Dec 2004
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Hi Dave,

No, no, there`s no forward sweep in the wings, for heaven's sake! It must be the screenshot.
I used some of the 3-views you find anywhere in the net. It is vital to put at least two plans from hopefully different sources over each other to find inconsistencies. I will explain later, new years party starting now!
I think about the spars once again. I'll use 3x5 for the back one, instead of 3x10.

Christoph.
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Last edited by chris-67; Dec 31, 2013 at 11:24 AM. Reason: bigfix
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Old Dec 31, 2013, 08:43 PM
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Ah, good!!

I have been collecting information on the He-162 for a while now because I planned to design and make one for my 80N turbine, once I finished my 1/4 ME-163 (turbine as well)

I asked about the drawings because If I was to be picky, there seems to be some slight shape issues in the nose area.. It seems to be too long forward of the canopy.

The BEST!! drawings I have found for the salamander by far are the R.V.Resin 3-view book. It has drawings in 1:72, 1:48, and 1:32 scales, but also dimensions and angles and cross sections for many other parts of the salamander.

I have added a small nose section drawing for you to compare. It might be ok, It's sometimes hard to know because it can depend so much on the angles of the screen shots etc...

Thanks

Dave

P.s. HAPPY NEW YEAR!!!!
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Old Jan 02, 2014, 05:50 AM
glattCAD Flugmodelle
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Germany, BY, Langweid am Lech
Joined Dec 2004
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You´re absolutely right, Dave,

the nose shape turned out to be most disputable to me, too. I just looked up, I studied 37 jpgs, gifs, bmp drawings and even more pictures from the internet.
In the end I decided for the nose of the "Yellow 6" of the Imperial War Museum, see image attached. The kit will contain two gauges for shaping the balsa block.

Christoph.
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Old Jan 03, 2014, 07:23 AM
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Antwerp, Belgium
Joined Sep 2004
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just to wet the appetite :)

Heinkel He 162 - JetPower 2012 (4 min 9 sec)



success with the build!!
Frank
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