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Thread: V2 LOC 4"

  1. #1
    Join Date
    29th September 2015
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    37

    V2 LOC 4"

    Hi, some years ago i built an Estes V2 which i lost last year in the field (simply forgot to pack going home..).
    I bought myself a V2 from LOC, in the Netherlands from reseller Modelraketten.nl. Although the V2 has of course a very dark history i simply like the design. I decided to use the paint scheme of the test version, and was fun to do with masking tape, spray cans etc.
    I was surprised by the weight of the components, and it took some effort to make a smooth transition from boat tail to body tube ans special attention was given to the fillets of the fins. This model was my first one completely built with epoxy. I will fly on CTI Pro 38 G motors.


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  2. #2
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    The construction process in images...


  3. #3
    Join Date
    30th January 2016
    Location
    US > OK > NE
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    Very nice! Did your model require extra weight in the nose?

  4. #4
    Join Date
    14th October 2010
    Location
    Middle TN
    Posts
    673
    I have not run across a flying V-2 that did not need nose weight. Even the captured V-2s flown at White Sands need 2000 lbs. in the nose to fly correctly. On those V-2s, lead was added if the instruments did not weigh enough.
    'Til next time,

    Mike Toelle

    NAR 31692 L1

    SAM 0373

  5. #5
    Join Date
    29th September 2015
    Posts
    37
    Hi,

    i did not do any calculations or testing on the balance, i simply built it according to LOC instructions: the bag of lead grain supplied with the model is epoxied into the nose cone. I will fly with 38 mm G motors (not heavier) so not the heaviest stuff available, it might be possible to fly it with less nose weight.

  6. #6
    Join Date
    26th January 2010
    Location
    Northern California
    Posts
    12,525
    Great paint job. Very clever use of the laser.
    NAR 91107, Level 2

    I really, really hate bugs.

  7. #7
    Join Date
    18th January 2009
    Location
    Virginia - Central
    Posts
    3,782
    Very Nice build.
    I have one of these kits...I think I'd like to build it with your paint scheme on it.
    Last edited by MaxQ; 13th May 2017 at 04:34 PM.
    We got two categories of pilots around here. We got your prime pilots that get all the hot planes, and we got your pud-knockers who DREAM about getting the hot planes.
    Now what are you two pud-knockers gonna have?... Huh?
    Pancho Barnes-
    The Right Stuff
    http://www.mwavs.com/0053148414/M4RS...udknockers.m4r

    Tripoli #2747

  8. #8
    Join Date
    9th April 2011
    Location
    Plano, TX
    Posts
    2,481
    Fantastic! You did a remarkable job, makes me want one.
    Jarrett Dorough

    Most people are average

  9. #9
    Join Date
    26th February 2017
    Posts
    15
    That looks very nice!

    I have finally started building my own loc v2. I spent a while researching the proper epoxy and preparation for the
    polypropylene plastic. As I plan on using an I motor, it is likely more important than for MPR.

    I have a couple questions:
    What are you doing for motor retention?
    What is your final weight, with nose weight?
    I am a little concerned about keeping the loaded weight under 1500 grams for MPR launched.



  10. #10
    Join Date
    18th January 2009
    Location
    Virginia - Central
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    3,782
    Quote Originally Posted by BradMilkomeda View Post
    That looks very nice!

    I have finally started building my own loc v2. I spent a while researching the proper epoxy and preparation for the
    polypropylene plastic. As I plan on using an I motor, it is likely more important than for MPR.

    I have a couple questions:
    What are you doing for motor retention?
    What is your final weight, with nose weight?
    I am a little concerned about keeping the loaded weight under 1500 grams for MPR launched.


    Interesting...what did you find out about epoxy and preparation for the polypropylene plastic.................................
    We got two categories of pilots around here. We got your prime pilots that get all the hot planes, and we got your pud-knockers who DREAM about getting the hot planes.
    Now what are you two pud-knockers gonna have?... Huh?
    Pancho Barnes-
    The Right Stuff
    http://www.mwavs.com/0053148414/M4RS...udknockers.m4r

    Tripoli #2747

  11. #11
    Join Date
    26th February 2017
    Posts
    15
    Quote Originally Posted by MaxQ View Post
    Interesting...what did you find out about epoxy and preparation for the polypropylene plastic.................................
    Keeping it short , the instructions for this kit are odd in that they specifically recommend SCOTCHWELD 1838, which is expensive at about 50$ for a 2 oz. This lead me into the deep hole of the data sheets and technical specification of 3M structural adhesives to determine if there was any reason for this epoxy to be chosen. I was not able to see why this epoxy would be recommended. Specifically, important here is that the material of polypropylene is classified as a "low surface energy" LSE plastic . These types of plastics readily beed waters so it dances around, which is what the molecules of the adhesive do.

    This results in properties such as DP190 having specified overlap shear strength of 650 psi for Wood, but only 90 psi for Polypropylene. And many of these epoxies have 1/10 the strength when above 150F!

    West System's G-Flex has adhesion data on a couple different treatments for polyethylene plastic, another LSEP, which I believe is comparable. They specify adhesion data for "80-git sand", "80-git sand, flame treatment" and "alcohol wipe, flame treatment" for polyethylene. It shows that there is significant benefit for using a flame treatment. This is nothing really new, but I was surprised to see 6X strength from this treatment.

    I ended up going with the G-Flex epoxy and 407 micro balloons for the fillets.

  12. #12
    Join Date
    29th September 2015
    Posts
    37
    Hi, the final weight of this one is 1150 gram, that is including nose weight and parachute. The parachute is a heavy one (120 gr), if neccesary to be replaced by a thin fabric one.

    Motor retention is done with two small S-shapes aluminium strips attatched to the bottum plate with wood screws. Click image for larger version. 

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  13. #13
    Join Date
    18th January 2009
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    Virginia - Central
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    Quote Originally Posted by BradMilkomeda View Post
    Keeping it short , the instructions for this kit are odd in that they specifically recommend SCOTCHWELD 1838, which is expensive at about 50$ for a 2 oz. This lead me into the deep hole of the data sheets and technical specification of 3M structural adhesives to determine if there was any reason for this epoxy to be chosen. I was not able to see why this epoxy would be recommended. Specifically, important here is that the material of polypropylene is classified as a "low surface energy" LSE plastic . These types of plastics readily beed waters so it dances around, which is what the molecules of the adhesive do.

    This results in properties such as DP190 having specified overlap shear strength of 650 psi for Wood, but only 90 psi for Polypropylene. And many of these epoxies have 1/10 the strength when above 150F!

    West System's G-Flex has adhesion data on a couple different treatments for polyethylene plastic, another LSEP, which I believe is comparable. They specify adhesion data for "80-git sand", "80-git sand, flame treatment" and "alcohol wipe, flame treatment" for polyethylene. It shows that there is significant benefit for using a flame treatment. This is nothing really new, but I was surprised to see 6X strength from this treatment.

    I ended up going with the G-Flex epoxy and 407 micro balloons for the fillets.
    Thanks!
    I remember reading about flame treatment for painting Loc nose cones on a website....haven't done that...yet.
    http://stason.org/TULARC/recreation/...otech-Nos.html
    http://faqs.cs.uu.nl/na-dir/model-ro...struction.html
    I have a Loc NC that I've made into a boat tail and applying tip to tip CF and attaching fins is the next step, so I'm looking for info on these Loc NC.

    This recommended epoxy IS expensive.

    http://www.skygeek.com/3m-021200-201...FdKLswodOvAEhw
    Last edited by MaxQ; 14th May 2017 at 03:56 PM.
    We got two categories of pilots around here. We got your prime pilots that get all the hot planes, and we got your pud-knockers who DREAM about getting the hot planes.
    Now what are you two pud-knockers gonna have?... Huh?
    Pancho Barnes-
    The Right Stuff
    http://www.mwavs.com/0053148414/M4RS...udknockers.m4r

    Tripoli #2747

  14. #14
    Join Date
    29th September 2015
    Posts
    37
    Final touch two Giant Leap rail guides: paint of body tube was sanded away locally (i love my Dremel tool), back of the 4" rail guide sanded too for better connection. Guides were glued in place using epoxy.
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    Parachute supplied with the model is too small: i wll use this 90cm one only for the main body, the nose cone will be recovered by a separate chute of 70 cm.
    First flight hopefully saturday at FTTS-2 of our local rocketry club DRRA.

    On small detail: the opening in the nose cone for adding epoxy/led has been sealed to decrease the neccesary ejection gas volume.
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  15. #15
    Join Date
    29th September 2015
    Posts
    37
    First flight on a CTI Pro-38-1G Smoky Sam (G) motor. Wonderful straight flight. No spin, perfect recovery.
    Click image for larger version. 

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  16. #16
    Join Date
    29th September 2015
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    37
    https://youtu.be/XH4ApVZWLOs

    Slo-mo of the start...

  17. #17
    Join Date
    26th February 2017
    Posts
    15
    Congratulations on the seccessful maiden flight. Thanks for sharing the nice video.

  18. #18
    Join Date
    14th January 2015
    Location
    North Carolina
    Posts
    69
    Great Job. Love those Smoky Sams. You might think about not using the nose cone loop as they will break. Drill a small hole 180 degrees apart and run a shock cord through them, much stronger.

  19. #19
    Join Date
    29th September 2015
    Posts
    37
    Hi,

    after the first flight of this V2 i discovered a crack in one of the fillets. I think this occured at landing (ca 5 m/s) and obviously the strength of the fillet is not as good as i expected. Maybe a fibre as filler would be better. What do you think ?

  20. #20
    Join Date
    26th February 2017
    Posts
    15
    Quote Originally Posted by BenAlbers View Post
    Hi,

    after the first flight of this V2 i discovered a crack in one of the fillets. I think this occured at landing (ca 5 m/s) and obviously the strength of the fillet is not as good as i expected. Maybe a fibre as filler would be better. What do you think ?
    That is a bummer dude. Do you have any picks? Is the crack in the middle of the fillet? Or at the adhesion point between the epoxy and the tail cone or fin?
    NAR #102778
    L1 - 4/7/17 - Loc IV H123W, LDRS36

  21. #21
    Join Date
    26th August 2014
    Location
    Hanna City, Il
    Posts
    51
    Quote Originally Posted by BenAlbers View Post
    Hi,

    after the first flight of this V2 i discovered a crack in one of the fillets. I think this occured at landing (ca 5 m/s) and obviously the strength of the fillet is not as good as i expected. Maybe a fibre as filler would be better. What do you think ?
    Late to the party.... but it appears you used too much micro balloons in your West Systems mix. They appear to be grainy and pure white. That weakened the epoxy. I have used G-Flex and micro balloons a number of times with no cracking. Since G-Flex is a relatively slow cure, add only enough micro balloons to get a creamy consistency. Let the epoxy mix set up until it gets to a peanut butter consistence then apply your fillets. Lots of info on fillets if you search TRF
    Joe Rice
    TRA 16467
    URRG
    L1 Mega Der Red Max - CTI H123 URRG 8/27/2016
    L2 MAC Performance Rayzor - CTI J285 URRG 8/28/2016

  22. #22
    Join Date
    26th August 2014
    Location
    Hanna City, Il
    Posts
    51
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    G-Flex and micro balloon fillets on my MDRM. Also be sure the surfaces are rouged up we'll before applying fillets.
    Joe Rice
    TRA 16467
    URRG
    L1 Mega Der Red Max - CTI H123 URRG 8/27/2016
    L2 MAC Performance Rayzor - CTI J285 URRG 8/28/2016

  23. #23
    Join Date
    29th September 2015
    Posts
    37
    Hi guys,

    the crack is in the middle of the fillet. I agree that the amount of micoballoons was maybe (too?) high: the epoxy matrix that should have given the fillet its tensile strength apparently is too much broken by the microballoons. The microballoons themselves are obviously too brittle and not able to withstand the short tension peak at landing. But: the fillet that Josef shows looks like pure epoxy with a little bit of microballoons in it. The advantage of having a paste that can be handled for a long time and which stays in place after applying is no longer there (?)
    For a next project I will apply a fibre filler in the epoxy. The fibre itself has its own tensile strength, and instead of weakening the epoxy it will even strengthen it...

  24. #24
    Join Date
    23rd July 2011
    Location
    Butte, MT
    Posts
    1,470
    You're exactly right about using fiber fillers. However, you could now apply a layer of fiberglass over your fillets to restore a great deal of strength.
    I would not add microballoons to epoxy in any application where I wanted structural support. Microballoons enable easy sanding and mass reduction but intentionally weaken any epoxy. What makes them easy to sand is their relative softness. Being filled with gas adds no tensile strength. I would use microballoons where I wanted bulk with little mass and where I intended to add a strength layer.
    West Systems puts out an excellent manual explaining their epoxies and different fillers. Here's the link:
    http://www.westsystem.com/wp-content...anual-2015.pdf



    Steve Shannon
    Steve Shannon
    L3CC, TAP, Director, Tripoli Rocketry Association

  25. #25
    Join Date
    29th September 2015
    Posts
    37
    Thanks Steve. For now I repaired the crack with some thin CA glue. I will see how it develops over the next flights, and if things become worse I may have to do some rework like you suggest. Have to do a lot of paintwork again then.....

  26. #26
    Join Date
    29th September 2015
    Posts
    37
    Yesterday this one flew for the second time. Again a very straight line, no spinerfect! And very imprssive this black smoke column in the blue sky! At landing again some minor crack in the fin fillets but i decided to do no specific repair now. The fins are glued with pure epoxy, there is no risk of losing the fins, and maybe the crack in the fillets do not develop further.

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