What are our opinions on fly away rail guides?

Sparkyflyer14

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They seem enticing to me, but don't you still have to deal with the added friction, weight, and un aero-dynamics attributed during the stage when they are still on the rocket? Interested to know. Thanks now for responses!
 

dhbarr

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In my experience they generally separate a couple of feet above the rail. If you're going very very fast, think about a tower instead -- the FARGs don't have much time to get out of the way and occasionally will get struck by a fin.
 

tim cubbedge

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I’ve used them many times. Only problem I’ve had is the surface they may land on. We launch on paved roads at 2 clubs I fly. Had an instance where they landed on road and they cracked.
 

G_T

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Unnecessary, yes, but even sounding rockets have done it. Dropping the front guide drops some drag. There isn't a reason to do it if it isn't going to be a high performance flight. And if the rocket is small enough, a tower is probably a better option.

I have zero experience with the commercial ones and haven't flown or designed my own. Not sure how suitable what is available is for high performance rockets. A front launch guide failure before exiting the rail is a very bad thing. That needs to not happen. But then it needs to release right out of the rail or it will smack the fins with considerable velocity and possibly do some damage to them. That is also a very bad thing. So they are a bit tricky.
 

mh9162013

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I've never used them, but from what I've seen and read, they should be used more often.

I've been brainstorming a way to create a modified FARG that can be used with a stock 1/8 or 3/16 launch rod.

Anything that allows me to get rid of a launch lug is worth looking into...
 

Sparkyflyer14

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I've never used them, but from what I've seen and read, they should be used more often.

I've been brainstorming a way to create a modified FARG that can be used with a stock 1/8 or 3/16 launch rod.

Anything that allows me to get rid of a launch lug is worth looking into...
Very interesting prospect. 🤔
Awesome to use, but if I get 5 uses out of one, it's a miracle - they break on landing. Never had on interfere with flight (hit a fin)

View attachment 532847
Cool. Whats that pad?
 

tsmith1315

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I've been brainstorming a way to create a modified FARG that can be used with a stock 1/8 or 3/16 launch rod.

Anything that allows me to get rid of a launch lug is worth looking into...

I used a KFLL fly-away lug from HPR in the past that worked great.

First run was made from poster board (curled by hand) with brass tube for 3/8" rod, attached with packing tape. The entire piece was then covered with packing tape for strength. I added two heavy rubber bands stretched tight to the back side to snap it away. Worked for H & I-power, but it did get closer scrutiny from the RSO the first time around.

It got nicked up by a fin, so I changed from poster board to denim. I don't remember how I attached the brass lugs to the denim. It seems like I wrapped the ends of the "Y" around them and used epoxy.

IMG_20220816_203524.jpg

IMG_20220816_203554.jpg
 

mh9162013

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I used a KFLL fly-away lug from HPR in the past that worked great.

First run was made from poster board (curled by hand) with brass tube for 3/8" rod, attached with packing tape. The entire piece was then covered with packing tape for strength. I added two heavy rubber bands stretched tight to the back side to snap it away. Worked for H & I-power, but it did get closer scrutiny from the RSO the first time around.

It got nicked up by a fin, so I changed from poster board to denim. I don't remember how I attached the brass lugs to the denim. It seems like I wrapped the ends of the "Y" around them and used epoxy.

View attachment 532875

View attachment 532876
That's awesome, thanks for sharing!

What I had in mind is similar to that, but obviously no where near as refined or polished. My biggest conern with this type of design is, as you already experienced, whether it can avoid getting hit by a fin.

Do you think this type of device will work with an LPR rocket, such as an Estes Yankee or Wizard?
 

cerving

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Awesome to use, but if I get 5 uses out of one, it's a miracle - they break on landing. Never had on interfere with flight (hit a fin)
I've used several different flyaway rail guides from various manufacturers in various sizes... and they all broke. Some after one flight, some after 3 or 4 flights. I had a K2050 tear one to shreds at launch... fortunately it lasted just long enough for the rocket to get off the rail. And they don't like being dropped from a few hundred feet, either. It would be nice if somebody made one out of aluminum instead of 3D printing them, but there isn't one out there like that. YMMV, of course...
 

Sparkyflyer14

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I used a KFLL fly-away lug from HPR in the past that worked great.

First run was made from poster board (curled by hand) with brass tube for 3/8" rod, attached with packing tape. The entire piece was then covered with packing tape for strength. I added two heavy rubber bands stretched tight to the back side to snap it away. Worked for H & I-power, but it did get closer scrutiny from the RSO the first time around.

It got nicked up by a fin, so I changed from poster board to denim. I don't remember how I attached the brass lugs to the denim. It seems like I wrapped the ends of the "Y" around them and used epoxy.

View attachment 532875

View attachment 532876
This seems like an exellent idea! I don't understand one thing. If The band around the rocket isn't tight, won't it slide down? and if its too tight, won't it creat execess friction?
 

Sandy H.

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I have never used a fly-away rail guide, either home brew or commercial. I have flown the conventional launch lugs and rail buttons, as well as towers and piston launchers (LPR only on pistons).

For the type of flying I do (boring, but easy) I doubt I'd go with fly away guides of any sort and would likely only fly a tower if looking to improve performance on a large rocket. Pistons were fun to play with, but don't scale well for larger rockets, I imagine.

The rocket I'm building now will use conventional 1515 buttons, even though a fly away guide might make it look better aesthetically.

Not saying it isn't a great option, but I am more interested in convenient flights vs. optimal performance flights. I wonder if dialing in the weights for the rocket vs. the motor chosen might be a more ideal flight that a constant weight with flyaway guides. Not sure, honest question.

Sandy.
 

mh9162013

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This seems like an exellent idea! I don't understand one thing. If The band around the rocket isn't tight, won't it slide down? and if its too tight, won't it creat execess friction?
I just made my own KFLL this evening out of this flexible foam mat/sheet that you can get at craft stores. It's about 2mm thick and it has a bit of little stretch to it.

I fitted it for a BT-20 main body tube and it's a nice snug fit such that the foam grips the rocket really well and there's no sliding around. However, the rocket + KFLL slides up and down the 1/8" launch rod no problem.

The only problem I see with my KFLL is that it has only a little "spring back" action. It's so light that I'm not worried about damage to the rocket if it hits a fin. But like Esterle mentions in his article, I'm betting my KFLL might get pretty high before it clears the rocket, so losing it may be a problem. I do plan on attaching a streamer to it, as suggested, though.
 

tsmith1315

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The only problem I see with my KFLL is that it has only a little "spring back" action. It's so light that I'm not worried about damage to the rocket if it hits a fin

Glad to hear you tried it!

I added two rubber bands to pull it away quickly. Each rubber band was added from the center portion to one of the ends, on the outside. This way the rubber bands were stretched tight as the lug was wrapped around the rocket.

For a LPR, I would try gluing or tying a short piece of elastic from the center lug to each of the outer lugs. the elastic pieces should be short enough to be in tension when wrapped around the rocket. That will give it some snap.


This seems like an exellent idea! I don't understand one thing. If The band around the rocket isn't tight, won't it slide down? and if its too tight, won't it creat execess friction?

You have to size it to fit snugly, and will have to "stretch" the lug a little to fit it on the rod. It will be in tension, you can see that in the first page bottom picture above. In that photo, it's obvious the center portion is pulling one direction on the rod segment, while the outside portions are pulling the opposite direction.

With the Y-shaped design, it's easy to trim the base of the Y a little at a time until it's tight enough to hold well when you fit it on the rod. Yes, it can create more friction, but not for long. You should still be able to slide it along the rod easily by hand. While getting the hang of it, use motors with a good initial spike to help with that concern.

It's just another tool for the toolbox, you can't have too many!
 

mh9162013

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Just an FYI:

Here's the prototype I made last night. The lugs are attached with CA glue and JB Weld. If it works, I'll do some tweaks, like seeing if I can find ways to reduce its weight and improve its "spring back ability." Tsmith1315's suggestions are one possibility, as is gluing a plastic strip to the outside of the orange foam. But I want to avoid adding any weight to the KFLL. This isn't b/c I care about performance as much as it is that I know a fin strike is inevitable and the less mass this has, the less likely there'll be damage to the rocket (or the strike will put the rocket into an unstable trajectory).
 

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TheBru

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I've used several different flyaway rail guides from various manufacturers in various sizes... and they all broke. Some after one flight, some after 3 or 4 flights. I had a K2050 tear one to shreds at launch... fortunately it lasted just long enough for the rocket to get off the rail. And they don't like being dropped from a few hundred feet, either. It would be nice if somebody made one out of aluminum instead of 3D printing them, but there isn't one out there like that. YMMV, of course...
If you have some extra all thread or wooden dowels mix that with a centering ring that has a large enough inner diameter to fit around the rocket your launching and boom, should survive the fall.
 

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Love'em, but 3D printed ones are likely to break (or bend) if they hit something hard. Have mitigated bending by replacing metals rods (in metal rods designs) with carbon fiber. Here is some testing we did a few years ago with some small rockets. The smaller slower rockets allowed us to see a little better what was happening.

 

mh9162013

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Update:

I used the above pictured Fly-Away Launch Lug (FALL?) with my Estes Yankee and it worked flawlessly off of a standard Estes 1/8" launch rod and pad.

The launch took place with an A8-3 engine and the Yankee reached an apogee of about 195 feet (per Jolly Logic AltimeterTwo; the low apogee was due to the Yankee being heavily modified with a payload bay and baffle - its weight with the altimeter, but no engine was about 33 grams). I'd estimate that the FALL fell away from the Yankee rocket at somewhere from 40-60 feet and landed roughly 20-40 feet away (east) from the launch pad.

Launch conditions: moderate breeze from the west with an ambient temperature of 81 degrees F and about 60% relative humidity.

I'm going to further tweak the above pictured design to make it a little smaller and lighter. Oh, and any future rocket build that wouldn't require a stand-off launch lug will have no launch lug at all and use the FALL.

Thanks again @tsmith1315 for posting that article!
 

Handeman

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I have ZERO experience with fly-away guides.

Is the initial drag on the rod/rail and drag until they come loose overcome by the lack of rail button/launch lug and actually provide higher altitudes?
Has anyone done 5 or so flights with the fly-away guides with the same motor to get a good average altitude and then add lugs, guides, or buttons and tried the same 5 motors to determine the differences?

The fly-away guides sound like they should add to achievable altitude, but do they really? How big of motor, burn time, flight speed, etc. do you need to have before the fly-away guides provide a noticeable difference in performance/altitude?
 

mh9162013

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Is the initial drag on the rod/rail and drag until they come loose overcome by the lack of rail button/launch lug and actually provide higher altitudes?
I think the answer to that question is, generally speaking, yes. But I think the answer depends on your rocket's design (high drag v. low drag), type of motor you're using (overall impulse and initial thrust) and type of fly away rail guide you're using.

Using my Estes Yankee and current FALL (fly away launch lug) set up, I'm betting I get little to no improvement over a conventional launch lug when launching off of Estes A8-3 engines. But if I used a C or D (18mm composite), I'm confident that the FALL with my Yankee would produce higher altitudes than my Yankee with a launch lug.

Here's my take from an LPR rocketeer. Assuming the fly away rail guide won't give you a net altitude increase for your particular rocket and motor set up, they're still worth it. This is because they allow you to avoid using a launch lug or rail button. This saves times on the build (which could be a disadvantage for some), saves on building supplies (yes, it's a small amount of glue or epoxy, but it's still a cost savings nonetheless) and avoids the aesthetic problem of a launch lug (which I think look hideous on model rockets).

EDIT: The above opinion is from the perspective of someone who (now) uses a FALL which allows me to still use a stock 1/8" launch rod. In other words, all I needed for a FALL set up was a launch lug, glue (CA and epoxy) and some 2mm EVA craft foam sheets.
 
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Gus

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I fly FARGs frequently and have set a number of altitude records with them. They are cheap enough that having to replace some is a non-issue. The major benefit of FARGs is they allow you to use longer guidance than most towers. Moving fast and heading straight up at the end of a tall rail is very beneficial for altitude flights.

One thing to watch out for is FARGs that fit too loosely on your rocket. I've actually had rockets fly through a loose FARG and strip their fins.

I very much like the guides from Apogee.
 

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Just an FYI:

Here's the prototype I made last night. The lugs are attached with CA glue and JB Weld. If it works, I'll do some tweaks, like seeing if I can find ways to reduce its weight and improve its "spring back ability." Tsmith1315's suggestions are one possibility, as is gluing a plastic strip to the outside of the orange foam. But I want to avoid adding any weight to the KFLL. This isn't b/c I care about performance as much as it is that I know a fin strike is inevitable and the less mass this has, the less likely there'll be damage to the rocket (or the strike will put the rocket into an unstable trajectory).

Update:

I used the above pictured Fly-Away Launch Lug (FALL?) with my Estes Yankee and it worked flawlessly off of a standard Estes 1/8" launch rod and pad.

The launch took place with an A8-3 engine and the Yankee reached an apogee of about 195 feet (per Jolly Logic AltimeterTwo; the low apogee was due to the Yankee being heavily modified with a payload bay and baffle - its weight with the altimeter, but no engine was about 33 grams). I'd estimate that the FALL fell away from the Yankee rocket at somewhere from 40-60 feet and landed roughly 20-40 feet away (east) from the launch pad.

Launch conditions: moderate breeze from the west with an ambient temperature of 81 degrees F and about 60% relative humidity.

I'm going to further tweak the above pictured design to make it a little smaller and lighter. Oh, and any future rocket build that wouldn't require a stand-off launch lug will have no launch lug at all and use the FALL.

Thanks again @tsmith1315 for posting that article!
I picked up a sheet of that orange foam from Hobby Lobby last night. 99 cents. Unbreakable, easy to find, and enough material to make a bunch of units. I'm on board with you - if it works as well as it did for you, I see no reason to use a launch lug on any rocket I plan to build.

One thing I thought of is to store it wrapped the opposite direction of how it wraps around the rocket, to give it a little more spring away from the BT when it clears the rod.
 

mh9162013

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One thing I thought of is to store it wrapped the opposite direction of how it wraps around the rocket, to give it a little more spring away from the BT when it clears the rod.
Great idea! I will try that...

I also created another version which is basically half as tall (and half the weight; 0.5 grams instead of 1.0 gram). I have yet to test it, though.
 

mh9162013

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Another update:

The BT-20 FALLs (the original version that's 65mm tall and the revised version that's 35mm tall) continue to work, although with my 3 recent launches with my Estes Wizard, the FALLs stayed on the rocket until ejection. Otherwise, they worked just fine and the Wizard flew well. I will modify these BT-20 FALLs with a strip of plastic on the outside to see if that will help reduce this issue.

I also made a BT-50 FALL, but it did not work. Because of the larger sheet of EVA foam, there was more give and flex in the FALL. As a result, on the test launch, the orange foam of the FALL tore at one of the corners due to sheer forces placed on it as a result of the flexing. With this flex, there was too much binding on the launch rod for the rocket to even leave the launch pad. I will need to find a more suitable material for this larger FALL.
 
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