Lakeroadster's X-Wing Alpha Build Thread

Had some time today to build the motor adapter. This will allow a C6-5 motor for the first few flights.

Open Rocket simulations shows a 588 foot apogee... should make recovery easier.

Saw this on another thread: Nifty tri-fold shock cord mount, but uses Kevlar. Posting it here so I don't forget to use it too.

Even if I use an elastic cord I can attach a swivel to the Kevlar.. and then when the elastic cord becomes dry rotted it will be easily replaced.

lakeroadster said:

Saw this on another thread: Nifty tri-fold shock cord mount, but uses Kevlar. Posting it here so I don't forget to use it too.

Even if I use an elastic cord I can attach a swivel to the Kevlar.. and then when the elastic cord becomes dry rotted it will be easily replaced.

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I don’t like trifolds. I don’t like anything that causes any irregularity of the internal surface that might keep recovery device from sliding out.

BABAR said:

I don’t like trifolds. I don’t like anything that causes any irregularity of the internal surface that might keep recovery device from sliding out.

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Then what about flange nuts for rail buttons? Or glue boogers for that matter? Or couplers?

kuririn said:

Then what about flange nuts for rail buttons? Or glue boogers for that matter? Or couplers?

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For my part, that's why rail buttons go below the laundry shelf

kuririn said:

Then what about flange nuts for rail buttons? Or glue boogers for that matter? Or couplers?

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Actually I have really come to like rail buttons for low power.

I get them here

https://rail-buttons.com/minimicro.html

With a little creativity, on a model like this might even "blend" them into the decor.

BABAR said:

I don’t like trifolds. I don’t like anything that causes any irregularity of the internal surface that might keep recovery device from sliding out.

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Makes sense. That being said, wouldn't installing the trifold deeper than the space occupied by the recovery device solve this issue?

I don't recall ever having a recovery device deployment issue on past rockets, related to the tri-fold mount just under the nose cone though.

an alternative to the tri-fold near the nose cone shoulder, if you have enough room, and in case you did not already anchor a cord to the engine mount, is to install a baffle, far down enough so you still have room for all the recovery stuff, and mount the shock cord to that.

GlenP said:

an alternative to the tri-fold near the nose cone shoulder, if you have enough room, and in case you did not already anchor a cord to the engine mount, is to install a baffle, far down enough so you still have room for all the recovery stuff, and mount the shock cord to that.

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The anchor cord in the thrust ring was my original intent but with a BT50 and a D Engine I bailed on that plan, fearful of burning through the kevlar in short order.

Seems like if the tri-fold was in the dog barf zone of the body tube that there would be nothing that could get hung up on it?

I'll make a CAD model of what I am planning and post it up here shortly. :wink:

I know it is horribly uncool and the high power guys might hate it, but a nice long 3/16 launch lug would be easier to incorporate on a fin root. Some folks still do use launch rods. Dare I say a 1/4 inch lug, that might be going a bit too far. A thin, flat paper trifold with a thin piece of kevlar mounted just below is nose cone shoulder is very strong with a nice glue job and decent surface area. You could extend the shock cord with a nice length of braided underwear elastic, whatever will fit. Soooo uncool to be seen in the fabric store, but it is a risk the old school builders take. If you get caught you can just give the old fella "my socks are falling down" or "my underwear are too loose" excuse. Coat your chute and tube in baby powder to make it slide real nice. If you get caught doing that you can use the "I need some baby powder for. . ." excuse. This is family forum so I will let you fill in the . . . on that one. Another uncool thing to use would be a dog barf sandwich to protect your delicate recovery gear for many flights. OK I have given way too much uncool advice here.

Time to be cool like FONZY: Rail buttons! Thick, super long kevlar on motor mount - heat protected and crocheted! Nomex heat shield or baffle! Anti zippering devices! Fiberglass bullet proofing! Never seen in a Hobby Lobby or Fabric Store again! MANCARD in tact!

GlenP said:

an alternative to the tri-fold near the nose cone shoulder, if you have enough room, and in case you did not already anchor a cord to the engine mount, is to install a baffle, far down enough so you still have room for all the recovery stuff, and mount the shock cord to that.

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Yep, many Semroc kits have that. The forward part of the baffle, where the shock cord is attached, would have sufficiently cooled the ejection gases to minimize any damage to the shock cord and recovery gear. ( But I still use a little wadding anyway, just in case). Might be a carryover from some of the old Centuri kits.

Daddyisabar said:

Time to be cool like FONZY

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Cool is the rule but, some times, bad is bad...

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Here's the tri-fold mount. Basically it installs into a short section of body tube that has been cut longitudinally to act as an internal sleeve.

Insert sleeve (no glue) into rocket body tube, just using body tube as a rounding fixture to hold sleeve,
Glue the tri-fold mount / kevlar shock cord,
Form fit the mount into the sleeve and let dry,
Add glue inside the body tube near the engine thrust ring,
Glue the sleeve / tri-fold mount into the body tube.

A swivel attaches to the kevlar for attachment to your recovery device of choice.

Also revised the location of the launch lug, and added another on the opposite side (Item #8 on drawings below). You call them launch lugs, I call them 20 mm cannons.

It's obvious you have some impressive engineering design skills. Just my opinion, but don't know if it's worth moving the shock cord mount from its' traditional location down to near the engine mount. You trade off the benefit of eliminating any recovery gear hangups for the increased exposure to hot ejection gases. If the shock cord mount is carefully assembled to lie as flat as possible in a BT-50 tube, I see a very small possibility of the parachute hanging up on it at ejection. Coat it with a uniform film of glue, especially the bottom, and it goes down even more. BTW I'm guessing your regular day job is engineering related?
You may want to consider having the shock cord swivel terminate just BELOW the edge of the main tube, to eliminate the possibility of zippering. Yeah, more of a pain in the butt to use but worth the extra effort.

I hardly even care about the actual rocket anymore. I just want to spend all day looking at those drawings. :jaw:

I think lakeroadster should change his name to "The CADMeister"! Tada! ( impressive flourish).

kuririn said:

BTW I'm guessing your regular day job is engineering related?

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It was, I am a retired Mech. Engineer / CAD monkey.

kuririn said:

I think lakeroadster should change his name to "The CADMeister"! .....

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The CADMeister is confused... :surprised:

Conversation went as thus...

GlenP said:

an alternative to the tri-fold near the nose cone shoulder, if you have enough room, and in case you did not already anchor a cord to the engine mount, is to install a baffle, far down enough so you still have room for all the recovery stuff, and mount the shock cord to that.

Click to expand...

kuririn said:

Yep, many Semroc kits have that. The forward part of the baffle, where the shock cord is attached, would have sufficiently cooled the ejection gases to minimize any damage to the shock cord and recovery gear. ( But I still use a little wadding anyway, just in case). Might be a carryover from some of the old Centuri kits.

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So attaching the kevlar down by the forward part of the baffle seems to be universally accepted as a good idea. But being a minimum diameter rocket ye ole X-Wing Alpha doesn't have a baffle, which was discussed....

lakeroadster said:

The anchor cord in the thrust ring was my original intent but with a BT50 and a D Engine I bailed on that plan, fearful of burning through the kevlar in short order.

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Since the tri-fold mount increases the chance of recovery deployment issues (opinions vary on the degree of such) pushing the mount down into the body seems logical (but not so far that it isn't protected by dog barf)..... but now I am reading...

kuririn said:

Just my opinion, but don't know if it's worth moving the shock cord mount from its' traditional location down to near the engine mount. You trade off the benefit of eliminating any recovery gear hangups for the increased exposure to hot ejection gases.

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Buzz kill.. I thought I was having my cake, and eating it too!

If the consensus is it's a waste of time, weight and materials... I'll forget the idea.

Don't know why you think a minimum diameter rocket cannot have a baffle. I'll post a pic of a BT-50 half moon baffle below. I modified it by adding a length of Kevlar with swivels at both ends, so it's actually a baffle/piston. I have a BT-20 one somewhere, but can't find it at the moment. Might be in one of my rockets.

Don't remember if this was previously mentioned here, but best solution would be using Chris Michealsson's replaceable Kevlar attachment method. It allows you to periodically remove and check the Kevlar for singe/wear, then return or replace it. Unfortunately it cannot be retrofitted to an already assembled rocket, since it needs to be built into the motor mount during assembly. Might be worth it if you plan on getting 25 or more flights from your rocket. It's described here:

https://www.apogeerockets.com/education/downloads/Newsletter338.pdf

Same method for minimum diameter rockets is described here:

https://www.apogeerockets.com/education/downloads/Newsletter343.pdf

Since you will be flying 24mm engines in a BT-50 dia. rocket, the second method above would apply.

My rockets usually don't make it to 25 launches. They wind up in a tree, on somebody's roof, or damaged beyond reasonable repair through repeated ejection charges or landing damage. Laters.

kuririn said:

Don't know why you think a minimum diameter rocket cannot have a baffle. ...

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Well, to clarify, what you linked to for the minimal rocket isn't a baffle, it's an engine block.

I had originally planned that (see drawing detail below) but as I previously stated, with the Kevlar right in the ejection blast, it seems like a failure waiting to happen.

If the rocket was large enough for a baffle style kevlar mount the dog barf would shield the Kevlar. But since in this instance the rocket is a minimal the tri-fold, mounted near the bulkhead, protected from the ejection blast by dog barf, seems to be a better design. Well, at least IMO.

Now I'm really confused. If you use the traditional method of gluing in the baffle then there wouldn't be any Kevlar directly exposed to the ejection blast (i.e. no cord glued to the thrust ring). The Kevlar would be attached at the front of the baffle and exposed to gases that have been "cooled" (somewhat) by the baffle passages. The passages should also block any flaming embers which can burn holes in the recovery gear, particularly mylar. But you would have to glue in a baffle for each rocket.
I came up with a sliding baffle/piston because I'm cheap, and didn't want to glue in a baffle for each rocket, instead swapping the baffles out for launch. That way, I only needed to make a baffle for each tube size, from BT-20 to BT-80. So 6 baffles in total, not counting ST size tubes. The baffle would still have to be attached on the lower end to a leader. That is a weak point of possible failure. But thicker Kevlar should last more launches. If I can get 25 launches before failure I'll be happy.
Putting dog barf on the tri-fold mount near the engine tube would not really protect the paper, in my opinion. The pressurized gases would blow the dog barf up towards the front, and expose the tri-fold mount to the hot ejection gases near the point of ignition. Not good.
Like I mentioned, the replaceable Kevlar method seems to be the best solution. But every method has its' pros and cons. I may be overthinking this, I feel a slight headache coming on. Going to lie down. Laters.

As always thanks for the input fellas.

kuririn said:

... Putting dog barf on the tri-fold mount near the engine tube would not really protect the paper, in my opinion. The pressurized gases would blow the dog barf up towards the front, and expose the tri-fold mount to the hot ejection gases near the point of ignition. Not good.

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Lots of paper body tubes hold up good... I'm figuring a paper tri-fold will have the same success. In any event the beast is born... the X-Wing will be the test mule.

• I used a retired business card for the tri-fold mount,
• Tied a knot in the kevlar then glued and folded the mount,
• Installed the tri-fold into the sleeve (short section of body tube cut along the tube spiral),
• Installed glue inside the rocket body tube using a dowel rod,
• Inserted the entire mount into the body.
• Created glue fillets around the internal mount by sucking wood glue into a clear straw, inserting straw into body tube, and blowing into straw.

Ever try to take a photo inside a 1" body tube? My success wasn't to great... but you can see the tri-fold doesn't extend into the body as far as the i.d. of the engine block.

I forgot to mention: Using the sleeve made from the body tube works really slick. I first sanded the glassine surface before cutting the tube. Once I cut the spiral the tube wants to open up. Therefore once installed inside the body tube it fits nice and snug.

P.S. Remember to take precautions against zippering.

kuririn said:

P.S. Remember to take precautions against zippering.

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Thanks. Per Open Rocket the rocket velocities are pretty minimal at ejection. But, nonetheless, maybe this ??

Micromeister said:

For LPR & MPR models I've found a simple doubled section of plain old masking tape over the foreward end of the Kevlar prevents zippering.
This is pretty much the only thing I do to models Micro thur BT-101 size Upscales. It's a little tricky getting the tape loop in the right spot but easy enough with a pair of tweezers.

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lakeroadster said:

Thanks. Per Open Rocket the rocket velocities are pretty minimal at ejection.

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I don't have much comment on the various other aspects of your shock cord mount, but I had to follow up on this: there are a hundred reasons why the velocity at ejection might not be the same (or even close) to what OR predicts. Do your best to get the delay just right, but also build under the assumption that it won't be.

In the one rocket where I had Kevlar extending out past the body tube (due to stupid error on my part) I did indeed put a fold of masking tape around it.


Knock on wood, that rocket will have its maiden flight on Saturday, and will not zipper.

This weekend they ate flying at Hartsel! If you can make it I would drive up to see this test flown.

Daddyisabar said:

This weekend they ate flying at Hartsel! If you can make it I would drive up to see this test flown.

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Thanks for the heads up.

Very confident the X-wing won't be there.. but I might. Do I need any kind of blood initiation or can I just show up?

Any ideas when the event hours are?

Daddyisabar said:

This weekend they ate flying at Hartsel! If you can make it I would drive up to see this test flown.

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Was this directed at me? I'm a couple of time zones away from you....

neil_w said:

Was this directed at me? I'm a couple of time zones away from you....

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Neil..... Daddyisabar and I are both in Colorado

lakeroadster said:

Neil..... Daddyisabar and I are both in Colorado

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Never mind then.

kuririn said:

Darth Barf

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That's what I'll be using for ejection charge wadding... :dark: