MadCow 3" Sport X L1 Cert Build

markkoelsch said:

Might I recommend that you do quite a few L1 flights before going to L2. There is A LOT you can and should learn before going L2 motors. I think you should look into electronics and dual deployment before your L2 and many rockets can REALLY have some kick ass flights on L2 motors. You should also get into and pretty much master some form of tracking whether RDF or GPS.

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Oh you bet I will get lots of L1 flights in before I try to attempt an L2 flight NEXT season....I'm planning on using a Jolly Logic Altimeter 3 (if they ever come back in stock) for tracking and basic flight data, and on my L1 flight I'll also be using a JL Chute Release, which I've already tested in "suborbital" flights with an Estes Star Orbiter that I built earlier in the season...I've got my Burrito style packing of the chute and release in a Nomex cloth down pretty well, thanks to the postings/pictures here on this forum...

Not really sure that I will ever feel comfortable with Black Powder-activated Dual Deployment, as I live in a "Nanny"state when it comes to almost all things gun related...I'm not going to go through all the red tape of a firearms purchasing card in this state just to buy Black Powder to load a deployment system....Sucks but we are limited to how much "freedom" we are allowed to have here in NJ....Frankly, I'm surprised that we still get to pay ridiculous HAZMAT fees to get larger motors delivered here in this state...If the officials really new what the FedEx trucks were bringing us, I'm sure it would come to an end....
Anyway, Thanks for the suggestions!

Cheers,
Franz in NJ

markkoelsch said:

That is nylon harness, right? You will absolutely want to wrap that in a nomex sleeve, or better yet replace it with tubular Kevlar. Nylon does not deal with the heat of ejection well.

Also, is that eye bolt a standard eyebolt, or is the eye welded shut? This is a potential point of failure that I would deal with. A cast eye, a welded eye, a small u bolt, or epoxying the harness to the motor mount can all work.

I realize I just popped a couple posts in here in rapid succession- just trying to impart a lot of collective experience in a hurry.

What will this rocket weigh with motor?

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To follow up, yup, welded eye, standard issue nylon strap from MadCow kit (really long length too), Nomex sleeve tube is on the way from Apogee this week...

On the next bird (4" MDRM clone), I will use Kevlar heavy Duty cord from the MMT to outside the BT, then Nylon from there to the Nosecone/Upper payload bay to give some "stretch/give"...Truth be told, I'm building the MDRM clone to most likely be the one for any L2 attempts NEXT season, or by that time, I'll probably be onto something larger/more L2-worthy!
Having fun all the way along the process though, and learning a lot from you fine folks here at the Forum!

Thanks for the info/suggestions, and keep 'em coming!

Franz in NJ

First ever epoxy fin fillets are all dry and ready for smoothing....

Here we are today, naked, loaded, and still no rail buttons.... Somebody please remind me not to forget them before I shoot this guy with some primer.... Or do we fly him naked and let him earn his paint job?
And here is the 29mm CTI case and 29/38mm adapter hardware

Starting to look and feel like something air worthy!

markkoelsch said:

That is nylon harness, right? You will absolutely want to wrap that in a nomex sleeve, or better yet replace it with tubular Kevlar. Nylon does not deal with the heat of ejection well.

Also, is that eye bolt a standard eyebolt, or is the eye welded shut? This is a potential point of failure that I would deal with. A cast eye, a welded eye, a small u bolt, or epoxying the harness to the motor mount can all work.

I realize I just popped a couple posts in here in rapid succession- just trying to impart a lot of collective experience in a hurry.

What will this rocket weigh with motor?

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Just mocked up everything with all laundry and chute release packed, H87 3G in place.....Found out I need a bigger capacity scale!
These are weights naked with no paint....

Sport X all in with no motor weighs 28.35 oz. (803.4gm)
H87 motor in the mounts weighs. 9.39oz (266.3gm)
Total Sport X with motor und alles. 37.74 oz (1069.7gm)

My Open rocket software estimates with H87 7 sec. delay, 1604 Ft.
with G57 7 sec. delay, 983 Ft.

I plan to set JL Chute Release for 300 Ft. with Madcow 30" chute...

Not quite "low and slow" but I'm sure that it will do....

What do you folks think?

thanks for any suggestions or ideas...

Franz in NJ

Lol, Low and Slow is my cert philosophy as well, I just tend to do it with fat draggy airframes (38 in a 4", 54 in a 5.5"). That's what's cool about this hobby, there's tons of room for folks to do things differently while enjoying themselves!

Your choice sounds quite reasonable given your prior experience and comfort level (although you could go harder ). My journey involved several G motors prior to certification, so I built for a solid H when I went L1. As long as you're learning and meet the requirements, all is good!

You say OR is predicting ~1/4 mile? That's easily withing visible range (highly recommend not painting it sky blue however). Have you tried adjusting the finish settings? paint, smooth paint, rough, etc,... can have a world of difference on altitude predictions.
-Word of info though, the Altimeter 3 is not a tracker. Its bluetooth range isn't great enough to serve if it truly goes out of site (or lands up in a tree). A couple good options are Eggfinder products that are inexpensive but require soldering up yourself, and the Missileworks T3 system ($150 complete tracker/receiver setup, just need a couple 1S li-po batteries for power).

Ah, nomex cord protectors. I keep intending to try them out, but I can't escape the fact that a strip of ductape folded over the cord works just as well and is way cheaper to install on 6 rockets.

If you do get talked into Kevlar on the next one, consider ending it before it exits the tube. Kevlar is narrower and can lead to sliced tubes (zippers) upon ejection. 4" Der Red Max eh? If you can fit a midsize J in there, you may get over a mile with it.

Fillets look fine. Is that 30 minute epoxy? They look better than the ones I did on my L1 with 5min. Did you scuff up the fin base and tube with sandpaper prior to laying the fillets? That helps it grab

300ft on the chute release should be fine. Some prefer to open it a tad higher to give plenty of room for the chute to unfurl properly, but you should be fine.

Thanks for the heads up with the trackers, there are two L2 Rocketeers in our local club that I can bounce some ideas from for tracking as well... What system would you recommend? Soldering doesn’t scare me, I’ve built some guitar effects pedals with circuit boards before can’t be that difficult !

Thanks for your recommendations!
Franz in NJ

Thanks for looking at the photos... That’s 5 min JB epoxy laid down with a monoject syringe... I scuffed the MMT, the fin bases, and the BT before the epoxy went down...
I’ll take your advice on the Kevlar too, don’t want any zipping tubes!

Thanks again for your input I appreciate it!
Franz in NJ

2 coats of filler primer went on yesterday...

Unless you are cramped for touchdown space, I would set the chute release a little higher until you know how long it takes the chute to open up. I’d try at least 500’.

Quick update, not my finest finishing work, but “good enough” for a possible Sub L1 flight (maybe) later today...

Any updates on this project?

I’ll have to post some pictures of the finished model, now it’s just a waiting game until I can actually launch my L1 attempt.... Our local club that has a HPR waiver here in NJ is within 50 miles of The President’s Bedminster Golf facility so we have been a “no fly” zone for most of the nice weekends....[emoji853]
Hopefully we’ll get a nice fall and I’ll be able to launch soon!

Here he is, all saddled up and ready to go.... Fingers crossed for next Saturday!

Best wishes for your cert!

Bat-mite said:

Best wishes for your cert!

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Thanks! I’ll report back either way, hope we get to launch!

Looks great! Level one I is within your grasp! Good luck!

JonathanOtt said:

Looks great! Level one I is within your grasp! Good luck!

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Thanks for the well wishes!
I will be sure to post results either way!

Cheers!
Franz in NJ

This guy flew a back up crew Level 1 Certification flight today, after the AMW MDRM Clone was successful earlier in the day... This guy went up on a CTI 3 Grain H90 with a 7 second delay and the JLCR set at 300’ as well...It landed about 100 yards from our launch site! Lots of fun can’t wait to send him up on some bigger stuff!

Sweet!

JonathanOtt said:

Sweet!

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Thanks! It was a really great, straight, clean, and high flight!
Even in a bit of wind, the model tracked really well, I can highly recommend this kit for a very predictable, medium low and slow L1 flight...
Can't wait now to put him up on some bigger stuff and get some great on-board video!

Franz in NJ

Franz, What is the length of the MMT on the Sport-X?

It's short (I have on laying in pieces on my workbench right now), it's only 8" long. But that is actually long enough.

Thanks Slothead. I'm putting the Sport-X on my Christmas wish list and was just curious. I'm planning to get a Loki 38/480 setup and the case is 11.5" long...that'll leave 3.5" sticking out of the forward end of the MMT tube...I realize that shouldn't be a be a problem.

Yeah Jonathan, the only thing I would make sure of in that case is to keep the forward centering ring as far forward as is practical to keep the moment reduced in front of it. Also keep in mind that you may have a more difficult time attaching a quick-link to an eye-bolt on that centering ring with the casing in place (you would probably attach it in advance of inserting the motor anyway). Have fun with it - it will probably be that long before I finish mine.

slothead said:

Yeah Jonathan, the only thing I would make sure of in that case is to keep the forward centering ring as far forward as is practical to keep the moment reduced in front of it. Also keep in mind that you may have a more difficult time attaching a quick-link to an eye-bolt on that centering ring with the casing in place (you would probably attach it in advance of inserting the motor anyway). Have fun with it - it will probably be that long before I finish mine.

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Yup, I attached the nylon shock cord to the eye ring before I epoxied in the MMT...To do it over again, I would use thicker round Kevlar from the eye ring to just below the body tube, then attach the nylon to that...Then I wouldn’t have to cover the nylon with nomex down to the eye ring....
I can’t recommend this kit enough though, really great flier so far!

I was thinking about getting a longer MMT tube and moving the top centering ring up to extend it to support a longer casing...maybe an extra centering ring too... It wouldn't cost much as far as weight added behind the CG and would give the peace of mind for support of the longer MMT.

JonathanOtt said:

I was thinking about getting a longer MMT tube and moving the top centering ring up to extend it to support a longer casing...maybe an extra centering ring too... It wouldn't cost much as far as weight added behind the CG and would give the peace of mind for support of the longer MMT.

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I bet it would work out fine.... Sim it first and see what it predicts....

JonathanOtt said:

I was thinking about getting a longer MMT tube and moving the top centering ring up to extend it to support a longer casing...maybe an extra centering ring too... It wouldn't cost much as far as weight added behind the CG and would give the peace of mind for support of the longer MMT.

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The motor really doesn't need any lateral support past the fins. It's retained and held back at the aft of your rocket.

That being said, extending the motor tube forward does cut down the tube volume that needs to be pressurized by the ejection charge. Your call