RW Go Devil 38 community build thread

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woferry said:
But as I went back to the launch pad to recover my fly-away rail guide, I couldn't find it, even in widening circles working out from the pad. When I went back to check out the video from the 2 ground cameras (up-looking action cam, 720p/240fps, handheld super-zoom 1080p/60fps) to see if I could tell when it came off, the rail guide apparently stayed on the rocket all the way to apogee.
Click to expand...

First of all, I am really sorry that they didn't separate. I would like to try to find out why. And of course if you PM me your address I will be happy to replace the guides with a new set incorporating all the latest improvements.

Anyway, a few questions:

  1. Do you happen to remember when you purchased the flyaway rail guides?
  2. Were they translucent or opaque in color?
  3. Did they have rail buttons or slides?
  4. Did they have one hinge or two?
  5. Did you put the rubber band on the guides, flex them a couple of times, and then put them on the rocket, or did the rubber band go on after the rocket was on the rail? The important question here is whether the guides had a chance to flex open and closed a couple of times before the flight (this ensures that the rubber band is tensioned properly) ?
  6. Are there any other unusual elements in this flight? Anything at all?

Any information you can provide would be helpful, and again please send me your address so I can dispatch a new set post-haste (and let me know if you prefer thin wall or thick-wall guides).

Thanks, I hope I can find a way to make it right.
 
wfcook said:
First of all, I am really sorry that they didn't separate. I would like to try to find out why. And of course if you PM me your address I will be happy to replace the guides with a new set incorporating all the latest improvements.
Click to expand...

Thanks a bunch for the offer, Bill. I was thinking of ordering two this time around just to have a backup, I wasn't expecting any offer of replacement, and I'm tempted to decline as much as I hate to say no to any free offer. :) I'm fine with just ordering two from AMW, but I will answer your questions for any help it might provide.

Anyway, a few questions:

1. Do you happen to remember when you purchased the flyaway rail guides?
Click to expand...

I purchased them from AMW on 4/30.

2. Were they translucent or opaque in color?
3. Did they have rail buttons or slides?
Click to expand...

Opaque (bright orange as it was the thin-wall model, P38T), 3 white rail buttons.

4. Did they have one hinge or two?
Click to expand...

There's a hinge at each end, I guess that means two?

5. Did you put the rubber band on the guides, flex them a couple of times, and then put them on the rocket, or did the rubber band go on after the rocket was on the rail? The important question here is whether the guides had a chance to flex open and closed a couple of times before the flight (this ensures that the rubber band is tensioned properly) ?
Click to expand...

A little from both columns. :p I had totally forgotten about the rubber band the first time I put the rocket on the rail. Thankfully I realized this before it was too late (just before I loaded the ignitor, though my altimeter was armed at that point), so I put the band on while it was on the rocket/rail, then removed the rocket from the rail, ensured that it opened and put it back on. So it didn't get flexed multiple times, only once, and likely not all the way open (I ensured that it started to open, but I was holding the rocket with one hand and the guide with the other at that point, so I'm pretty sure I didn't let it open all the way).

6. Are there any other unusual elements in this flight? Anything at all?
Click to expand...

I don't think so. I do have a ground video I'd be happy to send you if you wish, as I look more closely the guide might have shifted downwards a bit as/after it left the rail, this rocket is MD with pretty small fillets (curvature of a plastic spoon tip) so I don't know what it might have hung-up on. Initially the guide had a bit of a loose fit, before I took it to my first flight (XPRS a month ago) I had added small strips of duct-tape on the inside to narrow the ID of the plastic a bit as it was too loose on the rocket. When I got to the rail at XPRS this made it too tight of a fit on their rail, so I removed about half of the tape (I think the issue was more the large head of the screw at the end of the rail buttons, I definitely prefer the buttons with the countersunk screw, like this). I did not re-check the this launch here as I was a bit rushed at the pad, I can't say for certain that the tape hadn't maybe slid a bit and become sticky towards the rocket tube). I hadn't touched it since two successful flights at XPRS, but that was a month earlier (it went back into the bag in-between).

I will also state that I technically broke this guide the day I got it, but I was able to repair it. I totally didn't see that the two ends separated by sliding them, and assumed they simply snapped onto each other, but when I pulled them apart at what seemed to be the optimal angle for separation one of the two outer hinges broke. But it broke pretty cleanly along the axis it was printed, and with some CA I was able to re-attach the broken piece solidly, this was before my first two flights at XPRS so it obviously survived those and hinged freely. Or maybe the pieces came separate and I broke the hinge by snapping the two pieces together the first time, i forget.

Any information you can provide would be helpful, and again please send me your address so I can dispatch a new set post-haste (and let me know if you prefer thin wall or thick-wall guides).

Thanks, I hope I can find a way to make it right.
Click to expand...

You already have just by showing interest in this thread. I was not trying to speak anything bad about this product, it's a fantastic idea and a great implementation and it could very well be something I did poorly by being rushed (never a good idea of course), more that it might be a good idea for people to put their name/contact on the guide just in case it doesn't land close enough to find and someone else finds it later (bright colors certainly are a good idea). If there's any other comment I have about the product it's that explaining how it is meant to separate/connect would be a good idea (or else I totally missed it), and I'd much prefer to see countersunk rail guide screws vs. large pan-heads. In fact I was thinking about seeing whether I could change this myself on mine since I have some extra rail buttons (but I'm not sure if the screw size is the same as what the guide expects).
 
Thank you for your detailed post. There is a lot there and I will reply in detail when I have time to sit down and do so - these next couple of days are going to be pretty tied up.

Suffice it to say that the offer of a new set still stands. If you will send me your info I'll send you a set. The new guides are made of a different material which is a lot more durable and resistant to summer heat.

I'll give some thought to an instructional video to clarify things a little bit as well.

As for the rail buttons, I get that comment from time to time. I use the rail-buttons.com one-piece delrin buttons because (1) it makes no difference aerodynamically since they are only on the rocket for 4-6 ft, (2) They are significantly cheaper, and (3) I use #8-18 thread-cutting screws for plastic and they are a little harder to come by in a countersunk version (though you can find them at exhorbitant prices with security heads if you look hard enough). If there is an issue of the buttons fitting in the T-slot, that is another matter, so let me know if that is the case and I'll discuss it with Randy. Performance-wise it is a wash, though.

Bill _/)_
 
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wfcook said:
As for the rail buttons, I get that comment from time to time. I use the rail-buttons.com one-piece delrin buttons because (1) it makes no difference aerodynamically since they are only on the rocket for 4-6 ft, (2) They are significantly cheaper, and (3) I use #8-18 thread-cutting screws for plastic and they are a little harder to come by in a countersunk version (though you can find them at exhorbitant prices with security heads if you look hard enough). If there is an issue of the buttons fitting in the T-slot, that is another matter, so let me know if that is the case and I'll discuss it with Randy. Performance-wise it is a wash, though.
Click to expand...

I think for a normal application it might just squeak by (based on the 1010 rails I've used at Black Rock (Aeropac) and TCC, maybe there are others with a deeper channel or thinner walls or something, or maybe these are particularly worn where the guides normally contact the rails), I think the change here is that this guide pulls two of the buttons in one direction and the third in the opposite direction, so they aren't as centered on the rail, so they do seem to want to bind a bit more, I'll have to try to take a picture next time but there really was no clearance between the "V" part of the 1010 rail insides and the screw heads, so the guide was really running up/down the rail on the screw heads, not the delrin button itself. With an extra piece of tape inside the guide it was obvious that the heads were scraping the rail "V", with some of the tape removed the guide wasn't as tight of a fit on the rocket but the heads weren't scraping as much, and I could hold the rocket airframe away from the guide and slide the rocket up/down without the guide changing position on the rocket, so the friction of the guide-to-rocket was (slightly) greater than the guide-to-rail friction. So it does work but just barely. If the head was smaller (or recessed) there shouldn't really be any guide-to-rail friction, as I'd expect the button to "roll" if it was the thing in contact with the rail. Maybe I could try filing down the heads on the screws a bit (make them a bit less round and more conical) and/or applying some lubricant to the screw head (as people generally recommend when using the Acme aluminum conformal rail guides) might make things better also, the guide would still ride on the screw head but it might ride more smoothly. I bring a silicone spray can with me to the launches for my rocket with the Acme rail guides, but I didn't bring it to the pad when I flew this rocket.
 
Didn't have a chance to fly the GoDevil at MWP 13. I did a minimum diameter with LOC tubes and a J350 and an EggTimer TRS in the payload bay. Apogee blew out the chute and Archtype cutter released the main. Had a drogue attached to the apex of the 30" Dino chute that had a loop sewn in. Landed 1/4 mile away from
the cemetery to the east and 1.66 miles from my car.. I wanted to have backup for tracking but took awhile to figure out how to input lat/long into my 60CsX. Turns out I didn't need it as GPS Rocket Locator worked. Only issue is my Nexus 7 is wifi only and couldn't cache the maps. Nonetheless, it gave me two points and a datum line. Received the last packet at 175' in the air. I didn't see a thing. Went to 8500'. Nice knowing the drogue and main channels activated via the LCD receiver and could surmise the chutes were out by the rate of descent. Switched to a little 900Mhz Yagi for the hike to the last known position.
The GoDevil will have a TeleGPS and I have the BT receiver. The Android software allows one to cache the maps so I'll try it next. Maybe next weekend.
Kurt Savegnago
 
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Just reviewed this thread (in conjunction with finishing up my Rapton 38) and just wanted to say, it is an excellent resource with tons of good info.
 
dixontj93060 said:
Just reviewed this thread (in conjunction with finishing up my Rapton 38) and just wanted to say, it is an excellent resource with tons of good info.
Click to expand...

Still haven't been able to fly my GD38 though. Darn. Follow Jim's suggestion for the ebay and actually if one can get RW to make the upper main chute
tube one to two inches longer, that would help with the chute situation. Kurt
 
ksaves2 said:
Still haven't been able to fly my GD38 though. Darn. Follow Jim's suggestion for the ebay and actually if one can get RW to make the upper main chute
tube one to two inches longer, that would help with the chute situation. Kurt
Click to expand...

Yeah, I went with an Additive Aerospace sled as I hate the hassle for 29 and 38 bays.

And OK on the chute. I use Spherachutes for the small stuff along with a custom fit Kevlar pouch which I build myself.
 
ksaves2 said:
Did main chute deployment test but couldn't video it as I did it after dark. Used an EggTimer rocketry remote switch on a temporary sled. Had to mess around to get the 8 digit code to get it to "stick". Anyhow, space is very tight in the standard main bay and I had to ditch the quick link connection at the nosecone to get everything to fit. I did the test originally with .9 gram 4f and blew the daylights out of the thing. Fried the Dino cord protector. Soooooo.... I switched to a smaller chute, 24" instead of 30", tied the shockcord to the nosecone as opposed to using a quick link, just not enough room otherwise. Dropped the charge down to .63 gram and with two 2-56 nylon screw shearpins got a more civilized deployment when the button was pushed.

I used those plastic microcentrifuge vial holders and I put two sheets of Blue Quest wadding paper wadded over the end of the charge and wrapped the base of the shockcord protector with two sheets serially. That protrected the "protector" and nothing got fried this time. If I ditch both of the quick links on the shockcord might be able to get the 30" chute back in there. Now I need to drill the aft end of the ebay for two 2-56 shearpins and test that to determine the apogee charge from the sustainer.

I have a 38mm MD rocket out of LOC tubes that is going to be using an EggTimer TRS and a cable cutter to get the main unfurled. I've been able to test it with the remote deployment test feature on the TRS and I'll tell you that makes testing a heck of
a lot easier. Kurt
Click to expand...

Kurt
Who is Alexis? I want to talk to him. I have a Go Devil 38 that just shipped today. I am very interested in going Mach 2.5.
 
TomSmith58 said:
Kurt
Who is Alexis? I want to talk to him. I have a Go Devil 38 that just shipped today. I am very interested in going Mach 2.5.
Click to expand...

It was in another thread I don't remember the link. 18,000 feet. He laminated the fincan which was a smart idea.
Was going to fly mine tomorrow but launch was cancelled due to high expected winds. Kurt
 
So when you say laminated the fin can do you mean he applied tip to tip laminates?
 
I've done two more flights with my Go Devil 38 since my October Skies update. At the December LUNAR Snow Ranch launch the morning had low clouds, so I loaded up an H123W for a lower-altitude flight. My sim predicted 2835', actual altitude was around 2550'. No issues with the replacement fly-away rail guide (using rubber bands for the diameter adjust rather than tape shims), and a perfect DD flight, drifted about 630' from the pad but in the direction of my truck, landed maybe 100' from where I was parked (right in the roadway between two lines of parked cars).

I had intended to fly an I366R that same launch for my next attempt at a mile-shot (sim'ed to 7100'), and I was on the pad ready to fly with about 10 minutes left on the waiver, but the ignitor that came with the I366R just wouldn't show continuity at the pad. Turns out it was around 20Ω, no good (and checking ignitor resistance is now added to my pre-flight checklist). So I scrubbed that flight, and went back to Snow Ranch in February with the same motor still loaded, charges, etc., only re-charging the batteries in between (and a new ignitor of course).

The I366R took the rocket on a ~21 second trip to 8500' (well above the 7100' sim), top speed of ~713mph. The sim speed was close (1010 ft/s vs. 1045 ft/s per the SLCF), though the coast time was over 2s longer. Unfortunately the main came out at apogee, so it spent another 5 minutes in the air and landed over a mile away in a different field. But the Eggfinder didn't lose signal until it was basically on the ground, so I had a good idea where it landed, and once I figured out how to access other field took me right to it.

So far I've only been doing friction-fit on the nosecone, which worked about half the time. I've also been applying baby powder to the main chute protector since it's a tight fit in the bay with the 24" main, GLR small hexagonal chute protector and ~25' of 1/4" kevlar, so it's tough to do this without getting some on the part of the tube the NC rides on, which obviously doesn't help the friction fit. So I'll be drilling holes to accommodate shear pins moving forward, as I continue to push altitude with this rocket I can't afford to have the main come out that early again. I'll try to knock the heads off once the pins are in to keep the exterior smooth. But as my first FG rocket I'm really pleased with this kit, and I'll probably be looking for a >2 mile, >mach 1 flight on this rocket within the next few launches.

I also got a 3D printer mid-January, and have designed/printed sleds to hold an AltimeterThree in the motor area (clips onto the all-thread rod that connects to the MD retainer) and my Eggfinder & 2s LiPo (with magnetic switch option) in the nose. I'm still dialing-in my av-bay sled (SLCF, 2s LiPo and magnetic switch), the part placement is done but getting the wire routing right has taken a lot of tweaking, I'm not quite there yet.
 
Found out Thursday as I was prepping for Saturdays cancelled launch that the J350 I have loaded is a J500 as I marked the engine case with magic marker. I erase the motor indication with acetone once burned so I guess I'm going to use the
more powerful motor. I have 2-56 shearpins on the sustainer and the nosecone. Kurt
 
Hi Follks,
I have a Go Devil 38 and I bought a Slimline Qwik-Lok retainer. I am trying to figure out the best way to anchor my shock cord.

Can I use the MC38 Cesaroni Pro38 Delay/Eject-Closure Adapter on the end of my motor and screw an eye bolt into it? The loads from the shock cord would then go through the motor case to the Slimline. Or should I save the Slimline for later and buy the M38BE Minimum Diameter Motor Retainer. If I do that then I am stuck buying those retainer extensions.

Thanks
Tom
 
Personally I wouldn't be comfortable using the MC38 as a shock cord attach. The CTI charge wells aren't threaded themselves, you turn the MC38 against the well until it creates its own thread, but I wouldn't feel to comfortable subjecting that to any possible shock from an ejection event. For holding the motor in from the top I think it does fine, and others may disagree, it's just my personal level of comfort.

I believe when I got my Go Devil 38 it came with an extra fiberglass "centering ring" that was notched. Since it's a MD rocket it obviously wasn't for holding a motor mount, I believe it was for pinning the shock cord against the inside of the airframe, so you'd epoxy the ring and the shock cord inside (though working in this 38mm tube is never easy). So if you were retaining the motor some way other than with an MD38 I think that would be an option. Unfortunately this thread doesn't have any 'unboxing' photos from myself or others, so maybe that ring came with some other kit I got but I'm fairly certain it was this one.
 
Yeah Will I got one of those rings in my kit also. I still have it but didn't use it. Im just going to go with an open threaded closure or the plugged threaded closure.
 
TomSmith58 said:
Hi Follks,
I have a Go Devil 38 and I bought a Slimline Qwik-Lok retainer. I am trying to figure out the best way to anchor my shock cord.

Can I use the MC38 Cesaroni Pro38 Delay/Eject-Closure Adapter on the end of my motor and screw an eye bolt into it? The loads from the shock cord would then go through the motor case to the Slimline. Or should I save the Slimline for later and buy the M38BE Minimum Diameter Motor Retainer. If I do that then I am stuck buying those retainer extensions.

Thanks
Tom
Click to expand...

You probably saw my other response, but again the MC38 instructions say not to do this. I found a picture of the epoxy eyebolt, though, and the fellow did say he threaded a washer and nut on the back end -
20150226_180747_zpsbqkwussj.jpg


Also you do not have to buy those retainer extensions. I make my own from threaded rod and couplers. The measuring and cutting is a pain, but it sure is cheap!
 
How crazy is it to fly a Go Devil 38 on a CTI 6XL with just an RRC3 dual deploy altimeter? I don't have a tracker.
 
TomSmith58 said:
How crazy is it to fly a Go Devil 38 on a CTI 6XL with just an RRC3 dual deploy altimeter? I don't have a tracker.
Click to expand...

Very. There's plenty of room in the NC for just about any tracker. Go Devil with a 6XL will probably go about 12K at least, no way you're gonna get that back with eyeball tracking.
 
DizWolf said:
should be able to stuff this guy in a 38mm nosecone. https://bigredbee.com/brb900.htm :)
Click to expand...

I believe the EggFinder with a short antenna would be a tight fit. Look at these pictures: https://www.rocketryforum.com/showt...-community-build-thread&p=1459856#post1459856

The Tele-GPS pictured there is of course on the 70cm ham band and it just fit in the space alotted. I had to screw the N/C to the coupler and simply threaded the holes. I have PEM nuts I'm not going to bother with unless I strip out the screw holes. 850Mah single cell lipo fits on the other side of the sled. in a press fit fashion between the thrust blocks.

With the EF, I like to use a 1/2 wave antenna and that wouldn't fit in the GoDevil: https://www.linxtechnologies.com/resources/data-guides/ant-916-cw-hwr.pdf
If one uses a 1/4 wave antenna, they'll lose some of the effective output of the tracker: https://www.linxtechnologies.com/resources/data-guides/ant-916-cw-rh.pdf https://www.linxtechnologies.com/resources/data-guides/ant-916-cw-hd.pdf

A 1/4 wave wire would leave room but again, if going for the extremes, it would be better to have one's tracker as efficient as possible.

Hoping to be able to fly mine soon. Last launch scrubbed due to weather. Kurt
 
The Eggfinder definitely fits, even with what most would probably consider a large LiPo (Turnigy 950mA 2S and a Tenergy 900mA 2S, the Tenergy is slightly thinner). I bought one of APE-RC's 38mm head-end altimeter bay, back when it didn't have the integrated charge well. Initially I just had his FG sled with two holes drilled to capture the EF and a bunch of tape to hold the battery in place. I had a picture of it farther back in this thread, the EF had just gotten crunched from a very hard landing (tangled drogue-only). I picked up a 3D printer in January and designed a custom carrier for my battery and the EF. Looks much better now, holds things more securely and it's not as tight of a fit. :) I flew this to 8500' with a ~1.2 mi recovery distance and a great lock on the EF until it was just about on the ground, navigated right to it. This sled has a bracket between the battery and bulkhead that could hold a magnetic switch, but haven't decided whether I'm going to take advantage of that or not, this bay is easy to access before & after flight since there's a single set screw to lock the nose onto the bulkhead.

Original:
02-DSC03839.jpg

Printed:
GoDevil_Eggfinder_Sled.jpg
 
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Nice bulkhead Will. I test fit my EF with a 1/2 wave antenna and switched to the Tele-GPS 'cause I was looking out to eeeek out a little more range. The 1/2 wave put the EF past the coupler. I got mine setup for J motors.
Suffice it to say I'm looking forward to setting up a RW Formula 54 with an N/C mounted EggFinder using motor ejection with a Jolly Logic Chute Release for the main. Should be a sweet setup. More room in the 54mm diameter NC.
Kurt
 
Guys,
At one point I saw a presentation on rocket aerodynamics that included tidbits like a rule of thumb to size your fillets. Does anyone recall that and can I have a link?

I am thinking 0.25 will look proportionally correct for this rocket. What do you think?

Tom
 
That comes out to .32-.64 for an 8 inch edge. I have 0.25 in my CATIA model and it looks good. I'll try .3125 and see how it looks.

I am bummed. I flat patterned my plies for my fins and had it all done. Then I went to thicken the model where the plies were so I could model my plies in 3D. No real use just fun eye candy. CATIA crashed when I went to create my first 3D ply and I lost all my work.

Start over. I should finish after dinner and I'll post pictures.
 

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