EPM-010 Kitbash?

Discussion in 'Low Power Rocketry (LPR)' started by garndawg, Dec 17, 2013.

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  1. Dec 17, 2013 #1

    garndawg

    garndawg

    garndawg

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    Picked up an EPM-010 on the clearance rack at Hobby Lobby, mainly because of all the spare parts in it (8 PNC-5V nose cones!).

    I had thought of breaking the kit up into 2/3 larger 18mm rockets and kitbashing the BT-5's and nosecones into some 13mm Goonies. (Anybody got plans for a 13mm Goonie?) Might still do that, however...

    I was looking at it last night and started thinking about a three-stage gap-staged rocket out of it. Booster fin can (C6-0) up to coupler, 2nd stage up to the transition or just below (B6-0), then maybe 13mm sustainer w/ a long delay. I _think_ moving the little strake fins up to the sustainer would be enough longitudinal stability with the airspeed already established, so I'd just need to add some surfaces to the 2nd stage (what size?). I also thought of moving two of the pods from the main fins to the body tube at the stage joins. I'll put a streamer in these for recovery of the 1st/2nd stages. The others would still get kitbashed into Goonies.

    Thoughts?

    PS: Oddly enough, a search entered in the forums for "EPM-010" returns no results. The same search term in Google returns multiple threads on the forum like this one:
    http://www.rocketryforum.com/showthread.php?41370-Estes-EPM-010
    and this one:
    http://www.rocketryforum.com/showthread.php?42435-Possible-EPM-010-Clone-Cluster-2-stage

    Neither of which shows up on the forum search tool. Strange.
     
  2. Dec 17, 2013 #2

    samb

    samb

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    Confirmed your results using the forum search. Yes, strange.

    As far as the stager goes I like it. But the longest delay on a 13mm motor that I know of is the A3-4. I'd bet that the sustainer would still be going at a pretty rapid clip after only 4 seconds.
     
  3. Dec 17, 2013 #3

    Cl(VII)

    Cl(VII)

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    The forum search feature can't handle less than 4 characters and the dash doesn't count apparently. I had the same problem with a search for "X-15". There was a thread somewhere where Troj mentioned the 4 character lower limit, apparently it takes a lot more horsepower to search 3 characters. I, like you, use google for these searches.

    Also, I picked up an EPM-010 in the Hobby Lobby clearance section, and I've been looking at it trying to decide how to mess with it myself. I look forward to seeing what you come up with.
     
    Last edited: Dec 19, 2013
  4. Dec 17, 2013 #4

    eedetail

    eedetail

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    Interesting looking rocket even when built stock... reminiscent of the Mars Snoopers from long ago...
    But, dont get suckered into believing it is actually capable of Interplanetary Travel!
    I look forward to the build thread.
    TimE
     
  5. Dec 17, 2013 #5

    samb

    samb

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    Another mystery solved ! Thanks Cl.
     
  6. Dec 17, 2013 #6

    adrian

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    Add the combined masses of C6-0, B6-0 and A3-4T to Estes' estimated mass of the rocket, and you're pushing the maximum recommended liftoff weight for a C6-0. Normally I don't mind doing that, but a three-stager is another matter - if it doesn't have enough power to get going at a good speed during first stage boost, it's likely to start tipping over by the time the next two stages fire, meaning stage 3 is quite likely to end up going horizontal. This is why Estes' own three-stager, the Comanche-3, had a D12-0 for the first stage, and I suggest you do likewise. Especially since your model is going to end up heavier than a stock EPM-010.

    The small fins moved up to the top body tube, and the extra fins you'll need to add to what will become the second stage, will move the CP forward during first stage boost. You'll probably need some nose weight to put the CG ahead of it. Enlarging the main (now to become first stage) fins, and turning them upside down into more traditional swept back fins, should also help.

    Ignition of the third stage could also be difficult. The stock rocket is 35" long. I don't know where the coupler is, but if it's below where the small fins should go then your second stage is going to be more than 12" long - good luck getting gap staging to work, especially into the little nozzle of an A3-4T.

    The first stage will probably recover safely by tumbling but the second stage will come down ballistic unless you fit some sort of recovery device. Here's what I did on my Rheinbote, which needed long second and third stages:
    stage3.jpg

    That little streamer, made from Nomex, wrapped around the coupler and was held in place by the ring at the top of the coupler; then the coupler and streamer slipped into the gap between the next stage's body tube and motor mount. But Rheinbote's upper stage was BT-50, the same diameter as the EPM-010's main body, so there was a bit more room for that streamer even though the sustainer also had an 18mm mount. Doing the same to a booster which has to fit between a BT-20 body and BT-5 motor mount won't leave as much of a gap for the streamer and coupler. (The Nomex streamer was fireproof so would survive the blast from the sustainer's motor, and although not as long as a proper streamer it did destabilise the booster to prevent it from screaming down at high speed.)

    I'd be inclined to settle for two stages. Split the model just behind the small fins and replace them with fins large enough to make the sustainer stable. Then you don't have the long middle booster with all the problems mentioned above.
     
  7. Dec 17, 2013 #7

    T-Rex

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    I got one from the rack as well. I bought it specifically to cannibalize as I really don't care for the rocket.

    Maybe use a 1/2A3-4t in the sustainer. It is 2gm lighter and will give the sustainer less velocity to lose before ejection...
     
    Last edited: Dec 17, 2013
  8. Dec 17, 2013 #8

    Rich Holmes

    Rich Holmes

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  9. Dec 17, 2013 #9

    TopRamen

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    Always "Bash" a Kit if you are feeling up to it. It will force you into making Mistakes and thus learning from them. Plus, you'll ask more questions about what you are planning to do, also increasing your Knowledge.
    It feels good to finish a Kit, then realize that the only original Parts are the Body Tube and Nose Cone. Heck, re-design the Fins while you're at it!
    Go Wild! I do, and it feels Great!!!
     
  10. Dec 19, 2013 #10

    MALBAR 70

    MALBAR 70

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    I like the EPM 010 it has a unique style to it,not to mention it is an awesome flier.

    I'll be interested to see what you make of it. I like the idea of a multi- staged version.
     

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