An "R"-powered rocket build

[Rail Dawg]

Cut the inside diameter first.

Ah there you go.

When I was thinking how to do the cuts I figured if I cut the inside diameter first well then I don't have a place to put the centering hole for the circle jig cause there's no wood there.

Well now that you say it just make that inner cut and leave the circle in place. It's not going anywhere while I make the outer cut.

I knew one of you guys would come up with the simple answer.

Thanks!

Chuck C.

 

[Rail Dawg]

Entire airbags were used on our V2 as a contingency plan to get the chutes out, if they were not dragged out by the airframe sections separating (apex was attached with Velcro to the opposite section). They were at the bottom of a shallow plastic tub, with the chute on top.

No damage at all to the rocket?

The video seemed like it was too much force but if it's not as a contingency plan I like it.

Chuck C.

 

[Paulb06]

I've always been able to buy centering rings and bulk plates from the various rocketry web sites.

Well tonight I practiced cutting rings with my Bosch plunge-router using a circle-cutter jig. 3/4" birch plywood.

Can't remember who steered me in this direction but it works well and is actually kinda fun to do.

Let me ask a question:

I cut out the outside diameter of the ring (easy) then put that circle on top of 2 pieces of 2 x 4. Clamp it down to make the inner diameter cut but it's a pain as I have to move the clamp about 8 times because the router keeps bumping up against the clamp or the 2 x 4's get in the way.

Am I missing something obvious here? Is there a better way to hold down the circle real tight so I can cut the inner diameter?

Probably an easy answer but I can't think of it.

Chuck C.

I usually drill small holes and shoot a couple of drywall screws through the piece I'm cutting...layout where the all thread holes will go and put them there....or put them inside the center circle and install a clamp just before you finnish cutting all the way around....

 

[Reinhard]

I've always been able to buy centering rings and bulk plates from the various rocketry web sites.

Well tonight I practiced cutting rings with my Bosch plunge-router using a circle-cutter jig. 3/4" birch plywood.

Can't remember who steered me in this direction but it works well and is actually kinda fun to do.

Let me ask a question:

I cut out the outside diameter of the ring (easy) then put that circle on top of 2 pieces of 2 x 4. Clamp it down to make the inner diameter cut but it's a pain as I have to move the clamp about 8 times because the router keeps bumping up against the clamp or the 2 x 4's get in the way.

Am I missing something obvious here? Is there a better way to hold down the circle real tight so I can cut the inner diameter?

Probably an easy answer but I can't think of it.

Chuck C.

You can also use tabs:
1) Set router depth, so that you don't cut entirely through. Leave maybe 1/16" to 1/8" of material left or whatever feels right for you.
2) Cut first circle with limited depth setting
3) Set router to full depth
4) Cut most of first circle, but leave some tabs evenly spaced left, that hold the parts still in place
5) Cut second circle fully
6) Break out tabs and clean remains

Google "cnc milling tabs" to get an idea.

Another method is double sided adhesive tape, instead of clamps. This requires a flat sacrificial surface below.

Reinhard

 

[Paulb06]

You can also use tabs:
1) Set router depth, so that you don't cut entirely through. Leave maybe 1/16" to 1/8" of material left or whatever feels right for you.
2) Cut first circle with limited depth setting
3) Set router to full depth
4) Cut most of first circle, but leave some tabs evenly spaced left, that hold the parts still in place
5) Cut second circle fully
6) Break out tabs and clean remains

Google "cnc milling tabs" to get an idea.

Another method is double sided adhesive tape, instead of clamps. This requires a flat sacrificial surface below.

Reinhard

That's a great idea, plus your router bit will stay sharp longer if you make multiple passes instead of cutting full depth on the first pass...

 

[Ez2cDave]

Wow... looks a little TOO energetic doesn't it?

Chuck C.

Chuck,

I have been digging . . .

There might be another similar, less energetic, option available . . . Airbag units for motorcycles !

https://www.youtube.com/results?sp=CAM%3D&search_query=motorcycle+airbag

Dave F.

 

[Ez2cDave]

I've always been able to buy centering rings and bulk plates from the various rocketry web sites.

Well tonight I practiced cutting rings with my Bosch plunge-router using a circle-cutter jig. 3/4" birch plywood.

Chuck C.

Chuck,

Here's an idea I'd like to throw out there for consideration . . .

Instead of using a single sheet 3/4" plywood, what about using 6 stacked 1/8" Plywood Centering Rings for each "Ring Assembly", with Carbon Fiber "laminated" between them ?

Dave F.

 

[Rail Dawg]

Some very good ideas here on routing CR's.

You guys have definitely given me a plan.

The first 12" airframe and coupler parts will be here next week.

Gonna bang out some rings!

Thanks.

Chuck C.

 

[Ez2cDave]

You can also use tabs:
1) Set router depth, so that you don't cut entirely through. Leave maybe 1/16" to 1/8" of material left or whatever feels right for you.
2) Cut first circle with limited depth setting
3) Set router to full depth
4) Cut most of first circle, but leave some tabs evenly spaced left, that hold the parts still in place
5) Cut second circle fully
6) Break out tabs and clean remains

Google "cnc milling tabs" to get an idea.

Another method is double sided adhesive tape, instead of clamps. This requires a flat sacrificial surface below.

Reinhard

Reinhard,

You, sir, are a "Steely-Eyed Missile Man" . . . Great Idea !

Dave F.

 

[Nytrunner]

No damage at all to the rocket?

The video seemed like it was too much force but if it's not as a contingency plan I like it.

Chuck C.

The 1:1 scale V2 is the exact project I remember the airbags from, good thing OtT chimed in to remind me.

As far as recovery scheme for a large mass/volume project like this, those guys would be a great group to tap for ideas.

 

[Rail Dawg]

Chuck,

Here's an idea I'd like to throw out there for consideration . . .

Instead of using a single sheet 3/4" plywood, what about using 6 stacked 1/8" Plywood Centering Rings for each "Ring Assembly", with Carbon Fiber "laminated" between them ?

Dave F.

Not a bad idea.

Going to go with the 3/4" and glass them to the ID of the airframe.

Along with 8' long stringers it should be a robust design.

Chuck C.

 

[PedroTheRocketNerd]

Good question Dave.

I’d like to hear more discussion on getting a 60-foot Rocketman Pro-Experimental parachute to unreef correctly.

I’ve packed many a Rocketman chute up to “O” motor rockets and have never had a failure. They are that reliable.

The biggest concern of course is getting the drogue out and not damaging the drogue or the rocket. We’re talking about the probability of some pretty high speeds.

Haven’t decided on what method to use for drogue deployment. Jim Jarvis (smart guy!) has some really good ways to eject nosecones.

Here’s a link to a couple of his ideas:

https://www.rocketryforum.com/attac...itude-deployment-charges_may-2013-pdf.304204/

Am studying that now.

Chuck C.

For getting the parachute to deploy, Apogee Rockets ran a Peak of Flight newsletter about getting BP ejection charges to burn at altitudes of 40,000 feet or greater - much like what you are predicting for your rocket. The people needed to seal the charge canister so it held in ~1 atmosphere of pressure. I have attached the newsletter.

 

[OverTheTop]

The 1:1 scale V2 is the exact project I remember the airbags from, good thing OtT chimed in to remind me.

As far as recovery scheme for a large mass/volume project like this, those guys would be a great group to tap for ideas.

Airframe separation was by using high pressure (20 and 30 bar) compressed air on about 5" diameter pistons/couplers. Clever piston and gas release mechanism courtesy of RocketTroy.

The airbags were just to throw the chutes out if the chute apex had become detached from the other section. Freefall might have resulted in the laundry just sitting in the bucket.

Airbags did not participate in the separation process.

Any questions, just ask. PM me if you don't want to derail the thread too much.

 

[3stoogesrocketry]

I've always been able to buy centering rings and bulk plates from the various rocketry web sites.

Well tonight I practiced cutting rings with my Bosch plunge-router using a circle-cutter jig. 3/4" birch plywood.

Can't remember who steered me in this direction but it works well and is actually kinda fun to do.

Let me ask a question:

I cut out the outside diameter of the ring (easy) then put that circle on top of 2 pieces of 2 x 4. Clamp it down to make the inner diameter cut but it's a pain as I have to move the clamp about 8 times because the router keeps bumping up against the clamp or the 2 x 4's get in the way.

Am I missing something obvious here? Is there a better way to hold down the circle real tight so I can cut the inner diameter?

Probably an easy answer but I can't think of it.

Chuck C.

Chuck , put a wood screw thru the ring into the 2×4 where you are gonna place your rod.

 

[Rail Dawg]

Airframe separation was by using high pressure (20 and 30 bar) compressed air on about 5" diameter pistons/couplers. Clever piston and gas release mechanism courtesy of RocketTroy.

The airbags were just to throw the chutes out if the chute apex had become detached from the other section. Freefall might have resulted in the laundry just sitting in the bucket.

Airbags did not participate in the separation process.

Any questions, just ask. PM me if you don't want to derail the thread too much.

Heck no please post the good info here like you've done! This is a great way to let others know what works and what doesn't.

I appreciate your taking the time to detail what made that rocket successful.

Chuck C.

 

[OverTheTop]

I suspect you will have a little more altitude with an R in small diameter, compared to the 624' we got on our flight. You have no idea the relief we felt when we counted three inflated chutes [seriouslyrelievedicon].

If I have something to contribute I'll keep posting here.

 

[Ez2cDave]

I suspect you will have a little more altitude with an R in small diameter, compared to the 624' we got on our flight. You have no idea the relief we felt when we counted three inflated chutes [seriouslyrelievedicon].

If I have something to contribute I'll keep posting here.

624 feet ? That sounds "scary" . . . Is there a video ?

Dave F.

 

[Rail Dawg]

I suspect you will have a little more altitude with an R in small diameter, compared to the 624' we got on our flight. You have no idea the relief we felt when we counted three inflated chutes [seriouslyrelievedicon].

If I have something to contribute I'll keep posting here.

Most of us here can relate to that feeling when your rocket is under the mains!

There's so much that can go wrong. Seeing those three chutes brought up a cheer I'm sure.

Glad you're going to contribute here. I've actually incorporated many very good ideas into this current build.

Chuck C.

 

[boatgeek]

624 feet ? That sounds "scary" . . . Is there a video ?

Dave F.

 

[Ez2cDave]

Impressive, but still "scary" - LOL !

How was deployment before Apogee accomplished ( It was still moving upward at Deployment ) . . . Timer ? RC ?

Dave F.

 

[Ez2cDave]

Dave F.

 

[OverTheTop]

How was deployment before Apogee accomplished ( It was still moving upward at Deployment ) . . . Timer ? RC ?
Dave F.

We had a UHF radio system using DTMF codes to trigger events, primarily the separation. There were also three RRC3 altimeters (Thanks Missileworks!) which were also set up to trigger the separation, followed by the airbags, at apogee.

 

[Ez2cDave]

We had a UHF radio system using DTMF codes to trigger events, primarily the separation. There were also three RRC3 altimeters (Thanks Missileworks!) which were also set up to trigger the separation, followed by the airbags, at apogee.

Of course, being a full-scale V-2, that rocket was 65 inches in diameter. Chuck's rocket is 12 inches in diameter and the airbags might behave differently in the smaller tube, in terms of flame exposure, pressure, etc.

Also, the video I posted showed the internals of the actuator glowing bright orange, after activation. That residual heat might be a concern for Chuck to consider.

I'm going to err on the side of caution and recommend that Chuck do extensive testing, before committing to the use of airbag actuators.

Dave F.

 

[Nytrunner]

The chutes were contained in "buckets" that I can't imagine were much larger than a 12" airframe. OtT can confirm or deny

Nomex standard chute protectors would protect the rigging from heat problems similarly to how they're used for traditional dual deployment.

Regardless, we can be in complete agreement that ground testing is an absolute must.

 

[Ez2cDave]

The chutes were contained in "buckets" that I can't imagine were much larger than a 12" airframe. OtT can confirm or deny

Nomex standard chute protectors would protect the rigging from heat problems similarly to how they're used for traditional dual deployment.

Regardless, we can be in complete agreement that ground testing is an absolute must.

Agreed on the testing . . . 100% !

My main concern is an actuator either burning or blasting a hole in the airframe. Chuck is using a Carbon Fiber-wrapped Phenolic airframe.

Dave F.

 

[OverTheTop]

The chutes were contained in "buckets" that I can't imagine were much larger than a 12" airframe. OtT can confirm or deny

Nomex standard chute protectors would protect the rigging from heat problems similarly to how they're used for traditional dual deployment.

Regardless, we can be in complete agreement that ground testing is an absolute must.

You can see the plastic tub (Australia Post tub that normally transports mail items) in the pic here:



Fairly large tub, and IIRC the chute was only loosely packed in there. You can see the airbag clearly in the bottom of the tub.

 

[Ez2cDave]

You can see the plastic tub (Australia Post tub that normally transports mail items) in the pic here:

View attachment 371212

Fairly large tub, and IIRC the chute was only loosely packed in there. You can see the airbag clearly in the bottom of the tub.

Are there any "after" photo's, showing the condition of that plastic tub and the adjacent airframe, following the discharge of the airbag actuator ?

Dave F.

 

[Ez2cDave]

Chuck,

I found an interesting document on High-Altitude Wind data for Black Rock . . . PDF attached below.

Dave F.

 

[Ez2cDave]

This is what we DO NOT want Chuck's fins to do !

Dave F.

 

[boatgeek]

This is what we DO NOT want Chuck's fins to do !

Dave F.

I don't see why not--they stayed on right?!