Oberursel 100 HP Engine

Discussion in 'Gallery & Designs' started by Gil, Mar 2, 2004.

  1. Gil

    Gil Active Member

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    Hi All,

    Got to the engine on the Fokker EIII and decided that the engine supplied is not OEM...., It's OK if you're not to picky but I have friends who will be seeing (and critiquing) this model and will nail this item immediately. The last I remember of someone doing a great job on rotary engines was Leif Oh and his treatment of such on, I believe, a model called Tummelisa.

    I have all the drawings for the Oberursel U1 which was a German copy of the French Gnome engine and intend to reduce these into a buildable, realistic looking engine. The end result will be put into the parts bin as a vector file for others who wish to use it.

    One issue is over detailing. The engine as designed will be line drawings only ..., coloring will be helped by posting some photos of a finished, painted and detailed engine. I've been experimenting on ways to make the cylinder cooling fins look real and should have some showable results tomorrow. Detailing methods should continue to be added as they are developed and judged to be an asset to the tutorial..., maybe an album linked to the tutorial or something similar.

    My question is, how many of you are interested in such an effort. I thought as long as I was making the effort I might as well log it and post it. If there's enough interest then I'll put a little more effort into the tutorial part for clarity.

    Best regards, Gil
  2. Ron

    Ron Member

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    Count me in Gil! Engine detailing is as important as rigging in my eyes

    Ron
  3. rkelterer

    rkelterer Member

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    gil,

    do your friends build paper models ? whtaever, give them a printed kit, and let them build it. that will seperate the wheat from the chaff.

    anyhow, i would be pleased to see your detailed engine :D

    cheers
    raimund
  4. Ziga

    Ziga Member

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    I'm interested as well ;-)

    Best regards,
    Kaz
  5. Maurice

    Maurice Member

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    What does "OEM" stand for ?
  6. rkelterer

    rkelterer Member

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    Originally Equipped by the Manufacturer

    raimund
  7. Maurice

    Maurice Member

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  8. Gil

    Gil Active Member

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    Hi All,

    Raimund, yes they build plastic models and they take a beating from me for it. Some are beginning to consider card modeling as a possible new area for exploration. I am taking them one step at a time. One is now looking for an engine to pull his 1:72 Anzio Annie (if anyone has a source please let me know). I like making models that look real and are created from improbable media..., the less exotic the better.

    I took time today to take proportional measurements for the frontal section of the U1. Purchased a digital micrometer from Harbor Freight on sale for $19.95! It's made from stainless steel and works in either metric or english units. It made taking measurements off a photograph a task of ease. Why didn't I take them off the photo using software? Because it is simpler just to do it off a photo and then go straight to the drafting segment which begins just after I finish this.

    I am carrying out experiments in parallel to the formal development process as it allows more spontaneous idea flow. This is one way of saying that an idea of what media is to be used before drawings of the target model can be developed as paper constructs. The experiment pictured below is a cylinder from the original model. It was cutout, rolled and cemented with CA. The top was punched out with a leather punch and cemented to the top with CA. A mandrel was made from bamboo dowel and tapered to fit the inner diameter of the the rolled cylinder. This provides a way of firmly mounting the cyliner on the dowel so that a dremel tool can be used as a turning device. The outside of the cylinder was coated with hard acrylic modeling paste thickened with micro-balloons to lighten and make the hardened material more workable. All was allowed to dry overniight. The cylinder with mandrel was then mounted in the dremel tool and sanded to shape with 120 grit and finished with 400 grit. A method to mark off cuts for the cylinder cooling fins uses a 40 threads per cm metrc thread gauge to cut small grooves the length of the cylinder. The grooves then were deepened using a sharp ended dental pick. The photograph shows the bottom of the grooves to be rough..., this is most likely caused by the dental tool pick. Attention to cutting angle and tool tip edge will most likely solve this problem. Resulting turned cylinder was then smoothed with 600 grit and painted with liqutex bronze metallic paint and let dry. A wash of tamiya flat black and liquitex bright silver was then applied and let dry. The photograph below shows the result resting on a U.S. 5 cent piece which is 21.20 mm in diameter for reference (note that this picture magnifies the actual cylinder by around 5 to 10x depending upon screen size). Further work should improve the overall appearence.

    Best regards, Gil
    [​IMG]
  9. Maurice

    Maurice Member

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    What does "This is one way of saying that an idea of what media is to be used before drawings of the target model can be developed as paper constructs." stand for ?
  10. charliec

    charliec Active Member

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    Forgive ignorance but...

    I would have thought a rotary engine cylinders would be charcoal black from the cremated castrol oil which those engines spewed everywhere. I guess the crankcase would remain more or less aluminium in colour because it
    would be cooled by incoming fuel/air in the crankcase.

    I remember reading somewhere that constipation was never an issue for the
    pilots of rotary powered aircraft.

    Regards,

    Charlie
  11. Maurice

    Maurice Member

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    Charlie

    Do you think that was why PC 10 was such a dark colour.

    Maurice
  12. charliec

    charliec Active Member

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    Hi Maurice,

    I'm sorry - I don't understand the PC-10 reference - head full of normalised data structures might be to blame.

    Regards,

    Charlie
  13. Maurice

    Maurice Member

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    The very dark brownish greenish khakiish colour used on RFC/RAF/RNAS aircraft. Well you did mention the effects of castor oil. :wink:
  14. Gil

    Gil Active Member

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    Maurice,

    It means that you have to have an idea of the types of materials intended for use in modeling the subject before developing the paper outlines intended to be bent, folded and generally mutilated by the hapless modeler.

    Best regards, Gil
  15. Maurice

    Maurice Member

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    Oh - - - you might have said so - - - but if your using paper don't you already already know the type of material being used - - - :?
  16. Gil

    Gil Active Member

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    Hi All,

    Proceeded with two additional cylinder experiments for the Oberursel U1 engine. The photograph below shows the two results. The cylinder on the right is the simplest one to construct. A layer of acrylic modeling paste was spread on 67# stock followed by combing it out with the metric thread gauge (40 tpmm). A ruler was used on one side to steady the sweep of the gauge into a straight line. The modeling paste was allowed to dry. The cylinder as supplied was cutout, rolled, glued and painted. The second is the cutout, rolled and glued cylinder as supplied. A coating of hard acrylic modeling paste with micro-balloons was then applied and allowed to dry. The result was then turned to shape on a dremel tool and painted. It will be used as the template for the other eight.

    Best regards, Gil

    [​IMG]
  17. charliec

    charliec Active Member

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  18. charliec

    charliec Active Member

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  19. Gil

    Gil Active Member

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    Hi All,

    Drawing of the U1 so far. TurboCAD was becoming flakey requiring reinstallation. Lost files on the deinstall and had to start over.

    Best regards, Gil

    [​IMG]
  20. Gregory

    Gregory New Member

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    Gil, you are doing great job ;-)

    I think these pictures might be of a little help. I'd rather said that colour of the cylinders was steel or aluminium, not bronze.

    take care,
    Gregory

    PS. This pictures are inserted as attachment, if you are not logged, they are not visible. Sorry for inconvenience.