41% Downscale Binder Design Velociraptor (NOW With Spock's Ears!!!)

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K'Tesh

OpenRocket Chuck Norris
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Ever since I laid eyes on it, the Velociraptor has had a claw in my heart for a "I gotta build this..." project.



I gotta love Open Rocket. Using the .rkt file I found over on rocketreviews.com, I've been able to downscale it from a 86" long, 4" diameter, 29mm powered, monster of a rocket into something a little more manageable.

My plans are to build this as a 35.25" long, 1.64" Diameter (BT-60), 24mm powered mini-monster... However, instead of a single stage, I'm planning on a 2 stage design.



My scale work in OR has the nosecone as a 6.56" long ogive. I found Semroc's BNC-60G4 Balsa Nose Cone BT-60 6.6" Ogive an acceptable match for my needs.

I'm planning on building this with a payload section, but that isn't set in stone. To reduce the need for cutting up one of my BT-60's, I opted to make the payload section 5.78" long.



The main body tube is 18" long. I'm planning on a 24mm motor mount, capable of handling 3.75" long motors. The fins will be TTW, papered, 1/8" balsa, except for the talon fins. Those I plan to build up with a 1/32" thick plywood core and 1/16" balsa skins (to prevent me from messing up the shape in sanding). I'll sand them back down to 1/8" thick, then reinforce the leading edge with CA, and sand my taper out of the softer balsa.



The boat tail in the original is, according to Mike, the same nosecone as the nosecone used, but cut down. However, due to scaling issues, I opted to go with a cut down PNC-60RL that I had (damaged tip). My rocket will be scale in length, but the 24mm motor isn't something that I can alter. I'm happy with my solution (I should put a shout out to kjohnson for his suggestion of the PNC-60AH/RL). The shoulder of the booster's tail cone isn't shown in the image above, but will be present in the actual rocket.

I've still got some issues to work out (do I need a streamer for the booster? If so, how do I implement it? Any other options?)

I'm ordering downscaled decals are from Binder Design (Thanks Mike!).

Well, it's after 1 in the morning... I should get some sleep, I've got class in the morning. I'll add photos later.

Pointy Side Up!
Jim

[EDIT] In the early images of this build thread, I was using the fin shapes provided by rocketreviews.com's .rkt file.
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dixontj93060

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The Velociraptor is such a beautiful rocket!

Two-stage; interesting.
 

K'Tesh

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Downscale?

this one needs an upscale! I have the 4" and fantasize about a 6" variant.
I'd love to build this as a 4", and even a 6", but finances, time, and my education need to get some priority. Why not run your ideas through OR, and figure out what it'll take to build it. It might be closer than you think.

Build related news...

etoyoc informed me that a used E9 is .81oz (or 22.9gr). Now I'll be able to update my weights on OR... Looks like the booster comes in at about 2oz. With the empty engine still inside the booster, it looks to be a stable, tail down, ballistic object on recovery. I have yet to figure out the altitude of this upon sustainer's ignition.



Anybody know what the safety guidelines are for freefall objects? I don't want to hurt anyone, anything, nor my rocket, with my decision to go 2 stage.

One idea I have is to make a portion of the shoulder of the booster into an airbrake and use that to hopefully induce a slowing wobble. but implementing that would take some engineering, and how it would handle the flame, hot gasses, and other aerodynamic forces is a little daunting.

Thanks! TBC
Jim
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K'Tesh

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I think I cracked the issue of the booster's recovery...

Make a tunnel that is inside the sustainer. Carefully fold up a streamer and slide it inside the tunnel. Have one end of the streamer attached to the booster (possibly with a short coil of kevlar), and the other taped to a sacrificial tab of scrap body tube (which is in turn held in place by a rubberband against the motor).

When the sustainer ignites, the booster falls away, pulling out the streamer from the tunnel. The scrap cardboard protects the crepe paper from the direct blast of the motor as it pulls clear, then it is pulled away when the streamer is fully extended. If needed a 2nd or 3rd tunnel could be used with additional streamers.

Anybody know if this has been done before?

TBC...
Jim
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dixontj93060

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I have not been able to get booster recovery to survive without deploying it a good second (or more) before 2nd stage ignition (via a small separation charge) even when it was protected with Nomex.
 

K'Tesh

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I have not been able to get booster recovery to survive without deploying it a good second (or more) before 2nd stage ignition (via a small separation charge) even when it was protected with Nomex.
This is using Estes BP motors... I've never had problems with recovering the booster... None of my boosters were stable after separation, except for one, which happened to eject its friction fit motor, then glided down on its own (into a small tree (I walked up and picked it out of the thing w/o any problem)).

Getting the sustainer to ignite is a different story. I've lost two rockets to failed 2nd stage ignition, and one to booster explosion on the pad.
 
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dixontj93060

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This is using Estes BP motors... I've never had problems with recovering the booster... None of my boosters were stable after separation, except for one, which happened to eject its friction fit motor, then glided down on its own (into a small tree).

Getting the sustainer to ignite is a different story. I've lost two rockets to failed 2nd stage ignition, and one to booster explosion on the pad.
Oh sorry. Thought this was electronically controlled and w/AP motors.
 

K'Tesh

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Oh sorry. Thought this was electronically controlled and w/AP motors.
Not a problem... I hope you'll still enjoy the build thread. I've got parts on order, and they should arrive sometime in the next 24-96 hours....

OOOOoooohhh Goodies!

TBC
Jim
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K'Tesh

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Well, I'm a little stalled out on this build... My parts have yet to arrive.

That said... It looks like it would be possible to put 6+ feet of crepe streamer up into the tunnel I'm thinking of installing in the sustainer for the booster's recovery. One test has me a little worried though. It felt like the streamer could bind as it was pulled out.

An alternate idea is to attach the a 6' crepe streamer to a small ring that is larger than the BT-50 motor mount, but smaller than a BT-55. I'm kind of liking the ring idea as I feel it has less chance to bind inside and fail to deploy.

The idea for both is similiar... When the sustainer ignites, the booster drops away, tethered to the bundled streamer. I'm hoping that it would fall away before unwinding. When it is clear of the flame, a length of kevlar cord which is attached to a scrap of BT-50 Body tube (split in half) would pull free from where it is mounted to the sustainer's motor tube (by a rubberband). This little bit of tug IMHO wouldn't affect the sustainer's flight, but could help pull the streamer free if it's just a little stuck.

As I was typing this, I thought of another recovery method... inside the tunnel I was thinking of, put in a small "rotor" (made of a split length of body tube) attached to the booster with swivel attached to a Kevlar cord. This would be folded up inside the sustainer, and designed to automatically unfold when pulled free of its storage space. It would then just spin on its swivel, increasing drag as the booster falls. It would be small (maybe 8-10" (unfurled) long), but 2.0 oz isn't much.

I really want this booster to come down so it's reuseable, but I don't want anybody or anything hurt/damaged from an accidental hit.
 

K'Tesh

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Ok, here's where things stand...

I haven't figured out the exact method of slowing the booster's recovery. Parachute is out, streamer may be back in, rotors are questionable, drag fins are being considered.

[video=youtube;pytjJETpvFc]https://www.youtube.com/watch?v=pytjJETpvFc[/video]

The drag fins I'm thinking about are reminiscent of the MK82 Snake Eye bomb. Upon sustainer's ignition, these fins (which are hidden inside the tunnels) would be extracted, then the air flow would deploy them. Kevlar line would prevent them from imitating an umbrella in high wind. The fins may be attached directly to the tail cone's shoulder, or attached to a BT-55's coupler ring, a length of kevlar line, and a swivel.

I've cut out one of each fin (talon, main, booster) shapes, but build work on this has been stalled due to someone smiley-face-whistle-2.gif forgetting to order centering rings when the last order to Semroc.
 

qquake2k

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Okay, the Snake Eye drag fins are beyond cool!
 

K'Tesh

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Okay, the Snake Eye drag fins are beyond cool!
I always enjoyed loading them (usually 6 at a time via a BRU 3A's). They were a simple to load dumb iron bomb. None of that annoying 2 man team requirements like we had with the B61's and B57's (nukes), nor any of the pinging associated with the B38's (nuke drop shape).

If there was ever a way I could do it, I'd like an inert Mk82 Snake Eye as a conversation piece for my yard, however I'm sure that the neighbors would complain. Worse yet... How would I ever move it?

I'm still dreaming of building a 100% or 95% scale model of an AIM-9P. Armed with a (single) bang snap warhead, a 1/4A rocket motor, a toy gyroscope, and the camera I have sitting next to me here. That way I could say legitimately, it has an optical system, gyroscopic stabilization, and a real (small) warhead (armed), as well as a real (small... again) rocket motor (live). So what if I never launch it. It'd be a IMHO funny conversation piece (attached to my bicycle any time The Oregonian (newspaper) declares that there's another Car Wars battle). 9' missile attached to a Trek bicycle and a mud flap that reads:



I've never done that. This week. Yet.
The week is still young, my friend.
 
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K'Tesh

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Here's the inspiration for this build... I thought I'd share it with everybody. You can see it in person if you go to Tammie's Hobbies in Beaverton Oregon.



Ok, now back to updating things... You may have read that my VA benefits somehow got SNAFU'd. Well, they still are, and I'm "on waitlist". I doubt that I'll see anything before Thanksgiving, and probably not until January, unless I can find a way of pressing the state for them.

The parts I ordered arrived, and I was able to seal and sand the nose cone... it looks nice. I cut a chunk of BT-55 to try to create blades for either a rotor or Snake Eye recovery, but that's not promising. I think I'm back to folding a streamer in a sine wave pattern, and stuffing it into the tunnel, then hoping.

One little thing I forgot to add to my last order was 24mm BT-60 Motor mounts. I'm stopped dead until I can get some. My time is kinda tight as classes are winding down for the term so building (as much as I'd like to) is pretty much stalled on all my builds.
 
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K'Tesh

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Well, I managed to get several of the fins cut out... Not all, I have a single main fin and a booster fin to cut out. I'm using the template I printed from OR to give me the shapes. The larger fins are 1/8" balsa, and the talons are going to be made from 1/32" ply with 1/16" balsa laminated to it. I plan on making each talon out of 5 parts, the core, an outer section on both sides and an inner section on both sides. After gluing the outer sections to the core, I'll thin the fin down to 1/8" thick, then shape the leading edge. Once I'm happy with that, I'll harden the balsa with thin CA, then glue in the inner sections, and sand to shape. My idea is that this way I'll be less likely to have one side of the fin not match the other. After I'm happy with the final shape, I'll probably use CA to strengthen the fin and fill the grain.

Another idea came to mind for the recovery of the booster... To make the boat tail split much like the Snake Eye bombs, instead of having the drag fins tucked inside the upper stage's tunnel. Still, I'm leaning towards the streamer.
 

K'Tesh

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Thanks to Mike at Binder Designs, I've got updated information about the Velociraptor. The one that inspired me (found in Tammy's Hobbies in Beaverton, Oregon) is the first Velociraptor built. It flew 6 times, without a scratch, and uses a 38mm motor, rather than the larger motors used today.

Thanks to him, I've got authentic decals on the way, as well as accurate templates for the fins for my build. I haven't been Ok'd to share them, so until then, I'll keep them safe. Of course, this means that all the fins I cut out are a nice practice, but not going to be used. Oh well, I've got the balsa, so, no big loss.

I've updated the .rkt file to show the corrected shapes, and a more accurate color scheme.



I've made progress on the build, but no photos to share... yet.

Thanks to Eric, I've got some BT-60 Centering Rings (I've got the Gamma Upscale's engine mount made... that thread will be updated soon). With the fin troubles, I'm glad that I didn't do more, but the Velociraptor's engine mount is made, and tomorrow I plan on getting the corrected fins printed, cut out, and glued on (well the main fins at least). Paint will have to wait for better weather, but I hope to have a real build thread soon.

Pointy Side Up!
Jim
 
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Binder Design

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4" to 1.64" (BT-60) is 59% downscale according to my math. At least that is how I sized the decals, hopefully it is right. Your thread title suggests 41%, which would put you at 2.36" OD airframe.
 

Rich Holmes

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It's 59% less than 4", or 41% of 4". Does "x% downscale" refer to the % reduction or % of the original?

Is a "100% downscale" the same size, or nonexistent?
 

Binder Design

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It's 59% less than 4", or 41% of 4". Does "x% downscale" refer to the % reduction or % of the original?

Is a "100% downscale" the same size, or nonexistent?
Maybe I'm doing it wrong, but I always thought it was the former. Assuming that, a 100% downscale would be nonexistent. Regardless, the decals are sized to fit a 1.64" airframe.

I think it is the wording that is important here. For instance, to me a 75% "downscale" of a 4' diameter rocket would be 1" diameter. However a 4" diameter rocket that is 75% of "scale" would be 3" diameter. In my mind anyway. :)
 
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K'Tesh

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4" to 1.64" (BT-60) is 59% downscale according to my math. At least that is how I sized the decals, hopefully it is right. Your thread title suggests 41%, which would put you at 2.36" OD airframe.
My Math has it as:
4"/100 = 1.64"/X
1.64*100/4=X
164/4=41
X=41

Likewise
4"*.41=1.64"

Key thing here... The decals are for a BT-60 (1.64" OD body tube).

Really though, Mike, I couldn't do it without you.

Thanks!
Jim
 
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K'Tesh

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Enough of the downscale stuff ;)

I want to do an 8" upscale...
What's stopping you?

I'd love to see that (especially if you were to make it a 2 stage).

All The Best!
Jim
 

H_Rocket

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Time young Jedi...time...


And to a lesser extent the desire not to be yet another victim of DBR (Divorce by Rocketry)...
 

neond7

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Time young Jedi...time... And to a lesser extent the desire not to be yet another victim of DBR (Divorce by Rocketry)...
My fear as well. I figure, as long as we can both park on the garage, we will be ok. Of course when I'm in the middle of a build my SUV may sit in the driveway for a few nights. But so far, it all fits along the side of the garage. And along the back. And the workbenches. And the shed..... Oh man. *facepalm*
 

K'Tesh

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Ok, this isn't a virtual build, so let's get on with the photos...

Based on the info from Rocketreview's .rkt file, I understand that the nose cone of the full scale Velociraptor is 16" long. The boat tail used the same nose cone, but due to the inability to scale down the 24mm motor, I had to change the boat tail on my build.

First I settled on using the Semroc BNC-60G4 (6.6" Ogive) for my nose cone. Downscaled, it's .04" too long, but really...



I coated it with BSI's Super Thin CA to seal and harden it...



Then I 'paint' it with a Sharpie pen to help me see the defects in the hardened CA...



Next, I sand off all the black with 3M 320 grit wet/dry sandpaper...



To protect the shoulder, I slipped a scrap of body tube on it. Oh, while sanding, If I find that I've sanded through the CA (they look like grey smudges), I'll apply another coat over the affected area, and then use a different color sharpie (typically green) before sanding it down again.

I'll add a disk of paper with my name, SAM# (503), and email address on the back of the nose cone. I've started doing this to my balsa couplers as well. In a test of a baffle, I once blew the balsa nose cone off of a payload section, despite having a balsa coupler in place. This disk of CA coated paper seals the porous balsa, and will prevent a similar issue from happening in flight.



Next up... The boat tail/booster...

TBC...
Jim
 
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K'Tesh

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Mike informed me that, on the full scale Velociraptor, the nose cone and the boat tail are the same nose cone, but when I scaled down the rocket, the 6.56" nose cone wouldn't have the correct length/diameter to accommodate the 24mm motor I plan on using. Besides, hollowing the balsa would have been a royal PITA, if I could do it at all.

I've found that Estes seems to be pretty lazy when it comes to Ogive BT-60 plastic nose cones. After looking at them, it seems that they all could have been derived from the same foundation (a PNC-60RL). My choices were to use a Estes PNC-60AH (commonly found on Mean Machines, Super Neon XL, and Der Red Max rockets), a Estes Part #072665 (Solar Warrior, QCC Explorer), or the Estes PNC-60RL (Vagabond, Hi-Flier XL, STM 012, Magnum).



If I hadn't had a damaged PNC-60RL, I'd have gone for the PNC-60AH (it's more common), but since I had a damaged one, I opted to use it, and preserve my other intact nose cones for other projects.



I had a habit of cutting off the ends of my payload sectioned rocket's nose cones to extend them. On one of them, I made the mistake of painting it on the inside. The solvent in the paint softened the tip, deforming it.

Next I created a jig using spare parts (centering rings, scraps of tubing, to guide my cutting off the tip. I'll have to recreate it, to show how I did it, but not tonight.

I also scribed a separation joint to simulate the aluminum retaining ring on the boat tail.



Inside, you can see the paint that remains under some epoxy I used to repair a crack in the boat tail.



I've created a motor mount for the booster using a piece of BT-50, some masking tape, a Semroc RA-5060 centering ring, and a cut down RA-5060 centering ring. Some srips of balsa increase the gluing surface of the mount and aid in keeping it secure. I cut notches out of the forward centering ring to allow the fin tabs of the boat tail's fins to pass through. Later, I'll install a engine block, but not for now.



Here's the motor mount inside the boat tail. You can see a sacrificial section of body tube I've installed inside the boat tail. I've installed it as a way of protecting the inside of the boat tail from the hot gasses on separation. I won't glue it in, so that way I can replace it as needed. It also has the added benefit of smoothing the inside of the boat tail for the recovery device's ejection (there's a lip at the shoulder).



Here's an aft view image of the boat tail with mount installed. The masking tape is centering the motor mount inside the boat tail. If I was building this as a single stage, I wouldn't have had any centering rings inside the boat tail. I'd have a couple of them in the body tube, and tape to keep things centered. BTW... I used a little Super Thin CA to strengthen the motor mount's tube.



Thats enough for tonight...

TBC
Jim
 
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K'Tesh

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Ok... back to work.

I used the fin patterns from Rocketreviews.com to create my own fin patterns, but the Talon fin just looked... off. It was too angular when I compared it to the mental image, and later photograph, I had of Velociraptor #1.



Mike came through for me again, and supplied me with the fin patterns for each of the fins. He was also nice enough to allow me to share these with everyone. Here you can see how his pattern was interpreted by Open Rocket.



Now I haven't cut the new fins yet, but I had cut out fins based on the old RR's pattern.



So, I still need to cut new fins based on the original patterns from Binder Designs.
 

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