An "R"-powered rocket build

[Rail Dawg]

Chuck,

It looks like things are coming along nicely !

What is the status of the Nose Cone ?

We need to focus on Recovery System packing & deployment . . . Any more word on possibly using a skydiving school for Main Chute deployment testing ?

Dave F.

View attachment 384457

Good questions.

May end up with a filament-wound nose cone.

If not we'll beef up the inside of the current nose cone and strengthen the tip.

Going with a 50' Rocketman Pro-Ex parachute. Fortunately Buddy Michaelson at Rocketman will be at both LDRS and BALLS this year. He has offered to assist in the deployment bag packing of the parachute and recovery system.

So things are moving right along. Getting everything into place in just 5 months from receiving the rocket parts has been quite an effort. Thankfully there are guys like Pat G, the Engineering Dept, Levi Seaton and all the contributors to this thread to thank for this smooth process.

Chuck C.

 

[Ez2cDave]

Good questions.

May end up with a filament-wound nose cone.

If not we'll beef up the inside of the current nose cone and strengthen the tip.

Going with a 50' Rocketman Pro-Ex parachute. Fortunately Buddy Michaelson at Rocketman will be at both LDRS and BALLS this year. He has offered to assist in the deployment bag packing of the parachute and recovery system.

So things are moving right along. Getting everything into place in just 5 months from receiving the rocket parts has been quite an effort. Thankfully there are guys like Pat G, the Engineering Dept, Levi Seaton and all the contributors to this thread to thank for this smooth process.

Chuck C.

Chuck,

Either approach on the nose cone should be fine . . . I do think that incorporating a metal nose tip, with a rounded tip is critical, due to aerodynamic heating issues.

Are you going to do any "low pressure" testing of the Ejection Charge(s) for the Drogue ?

The air pressure at 40,000 - 45,000 ft AGL is only about 2-3 psi . ( Being a commercial airline pilot, you probably already knew that - LOL ! )

The upper air temperature could exceed -100 Deg F ( Below Zero ) at 40,000 - 45,000 ft AGL . . . ( C to F conversion 9/5 C + 32 = F . . . CHART & PDF BELOW )

https://www.researchgate.net/figure/Altitude-and-Average-Air-Pressure-Chart_tbl2_263235789 ( CHART BELOW )

I'm proud and honored to be one of the "Steely-Eyed Missile Men" on the Support Team !

Dave F.

STANDARD ISA CHART ( International Standard Atmosphere ) - FULL PDF file below

 

[boatgeek]

[QUOTE="Ez2cDave, post: 1889604, member: 207”]
Are you going to do any "low pressure" testing of the Ejection Charge(s) for the Drogue ?

The air pressure at 40,000 - 45,000 ft AGL is only about 2-3 psi . ( Being a commercial airline pilot, you probably already knew that - LOL ! )

The upper air temperature could exceed -100 Deg F ( Below Zero ) at 40,000 - 45,000 ft AGL . . . ( C to F conversion 9/5 C + 32 = F . . . CHART & PDF BELOW )

https://www.researchgate.net/figure/Altitude-and-Average-Air-Pressure-Chart_tbl2_263235789 ( CHART BELOW )

I'm proud and honored to be one of the "Steely-Eyed Missile Men" on the Support Team !

Dave F.
[/QUOTE]

-56.5 C is closer to -70 F. Still awfully cold but not as bad. Also, the rocket itself won’t be at that temperature, since parts will just have been subject to aero heating and the coast time limits the amount of heat transfer. I wouldn’t think that the ejection charge would have cooled much at all, though I’ll defer to those with experience. Lack of air for heat transfer between BP grains is a definite issue if the charges aren’t airtight and in a long barrel.

 

[Wallace]

wow...

 

[Ez2cDave]

[QUOTE="Ez2cDave, post: 1889604, member: 207”]

-56.5 C is closer to -70 F. Still awfully cold but not as bad. Also, the rocket itself won’t be at that temperature, since parts will just have been subject to aero heating and the coast time limits the amount of heat transfer. I wouldn’t think that the ejection charge would have cooled much at all, though I’ll defer to those with experience. Lack of air for heat transfer between BP grains is a definite issue if the charges aren’t airtight and in a long barrel.

Hmm . . . "Airtight Charges" . . . I wonder if the Drogue charges could be sealed ( maybe using "Food Saver" bags ) and bring along their own "air supply" for deployment ?

Also, with the air pressure being only 2-3 psi at 40,00 ft AGL, the Drogue charges will have to be considerably heavier than they would be at lower altitude, in order to adequately pressurize the airframe for deployment !

HEAT & COLD . . .

That got me thinking about another potential problem . . . "Slip-Fit" problems due to thermal change in flight .

Depending on how components expand and contract, due to temperature changes in flight, a situation might arise that could cause "binding" or other issues, possibly preventing deployment !

Dave F.

 

[levi seaton]

A little more progress on the tower

 

[Rail Dawg]

A little more progress on the tower

Hydraulics! Gotta love it.

Chuck C.

 

[Theory]

Chuck,

how would you say the airframe build is going? more or less to plan or have you been surprised by this, that or the other?

no doubt you put a great deal of engineering and planning into this, just curious as to your impressions thus far.

would you say that the coupler / CR / stringer assembly is working out the way you had anticipated?


I only ask as I know from personal experience that once a project begins and pieces actually start going together one might see a better or more efficient way to accomplish the task at hand. even if its something as simple as a change to the "order of operations." I know you had one slight design change that no doubt served the project well.


really looking forward to some motor data to give "us" (read you) more accurate sims!

 

[Rail Dawg]

Chuck,

how would you say the airframe build is going? more or less to plan or have you been surprised by this, that or the other?

no doubt you put a great deal of engineering and planning into this, just curious as to your impressions thus far.

would you say that the coupler / CR / stringer assembly is working out the way you had anticipated?


I only ask as I know from personal experience that once a project begins and pieces actually start going together one might see a better or more efficient way to accomplish the task at hand. even if its something as simple as a change to the "order of operations." I know you had one slight design change that no doubt served the project well.


really looking forward to some motor data to give "us" (read you) more accurate sims!

Good questions Theory!

It’s going well. It helps a lot to have the Engineering Dept (and you guys) catch mistakes and offer better solutions.

I really like the coupler-assembly approach to building a rocket. It’s certainly the way it’s going to be done with future rockets.

We should be testing a Q motor fairly soon once we decide on the venue.

Chuck C.

 

[Theory]

cool deal!

it always feels good to see a project turn out well and the way you planned.

when everything lines up and slides into place you have that "hell yea" feeling knowing that you did what you set out to do.

 

[Ez2cDave]

It helps a lot to have the Engineering Dept (and you guys) catch mistakes and offer better solutions.

I really like the coupler-assembly approach to building a rocket. It’s certainly the way it’s going to be done with future rockets.

Chuck C.

Chuck,

Modular construction, using stacked coupler segments, allows for many issues to be addressed at one time . . . Easy "Slip-Fit" bonding to the airframe . . . Reliable filleting of couplers . . . Proper bonding and reinforcement of Stringers . . . Length "adjust-ability", on the fly, if necessary . . . Very strong . . . Etc, etc, etc.

I really like the "team approach" and the "compartmentalization" of the Work Load . . . Each Member, of each "team", brings their own set of skills and knowledge, their own methods of analysis and design, all with their central focus being the success of the project, regardless of their level of actual involvement !

In many ways, we are a "scaled-down" version of what NASA was like, in the 1960's . . .

As I have often said, I am proud and honored to be one of the "Steely-Eyed Missile Men" of the Support Team . . .

"Adapt & Overcome - Failure Is Not An Option" . . .

Many thanks, Chuck !

Dave F.

 

[Rail Dawg]

Well said Dave.

Thanks!

Chuck C.

 

[davdue]

HEAT & COLD . . .

That got me thinking about another potential problem . . . "Slip-Fit" problems due to thermal change in flight .

Depending on how components expand and contract, due to temperature changes in flight, a situation might arise that could cause "binding" or other issues, possibly preventing deployment !

Dave F.

View attachment 384510

Dave,

I can vouch for issues with that. My first L3 attempt was a shorter version of my avatar photo. The 76/6000 Loki case went up the middle of my Av-bay. Fully ground tested everything and the drogue deployed very well. But during flight either aero forces or heating of the motor didn't allow the rocket to separate at apogee so down it came ballistic until 900 AGL when the main fired and the 120" parachute deployed and tried to flip the rocket and slow it down. It tried admirably but alas matey it wasn't up to the task and ripped some shroud lines and the shock cord after flipping the rocket around. However the fin can did survive with minimal repairable damage just all the airframe parts had to be rebuilt. Of course this time it was a longer rocket allowing for room for the motor case and drogue. It was a fiberglassed phenolic airframe that was patterned off of Performance Rocketry's fiberglass Gizmo XL with the same configuration. Apparently the fiberglass is more forgiving to slip under heat and pressure. My second attempt was flawless.

 

[dwightr]

Hmm . . . "Airtight Charges" . . . I wonder if the Drogue charges could be sealed ( maybe using "Food Saver" bags ) and bring along their own "air supply" for deployment ?

Also, with the air pressure being only 2-3 psi at 40,00 ft AGL, the Drogue charges will have to be considerably heavier than they would be at lower altitude, in order to adequately pressurize the airframe for deployment

Will drogue charges need to be heavier because of low outside pressure? I was thinking that differential pressure was really the goal and outside pressure is really indifferent.

 

[Rail Dawg]

My line of thinking is sealed charge cannons.

BP in a black film canister with 2 electric matches. Extra space in canister filled with wadding.

(2) 38 mm G-12 cannons each with a film canister inside. Wadding filling the extra space there too. Top of cannon will be lightly sealed with epoxy. Upon ignition the BP should have enough volume to cause separation. Will of course ground test this to ensure G-12 can handle it. Will even triple the load to fully test the G-12 before putting into rocket for normal test.

Blow it up or blow it out. The rocket itself can handle significant internal pressure.

Feel free of course to discuss and point out potential problems. I’m not going to vacuum test the charges. Jim Jarvis has done excellent research and testing with BP cannons. I’m currently comfortable with the above approach.

Thanks!

Chuck C.

 

[dwightr]

I realize that BP may be less energetic at high altitude because of low heat transfer affecting burn rate but my question was whether altitude has any effect on the pressure required to separate the airframe. As an example if the desired separation pressure is 12 psig then the internal pressure during a sea level test is 26.7 psia while a 50000' deployment would only require about 13.2 psia to get a 12 psig differential between internal and ambient pressure. It looks to be like the difference in powder charge is entirely due to burn efficiency not pressure differential.

 

[Paulb06]

My line of thinking is sealed charge cannons.

BP in a black film canister with 2 electric matches. Extra space in canister filled with wadding.

(2) 38 mm G-12 cannons each with a film canister inside. Wadding filling the extra space there too. Top of cannon will be lightly sealed with epoxy. Upon ignition the BP should have enough volume to cause separation. Will of course ground test this to ensure G-12 can handle it. Will even triple the load to fully test the G-12 before putting into rocket for normal test.

Blow it up or blow it out. The rocket itself can handle significant internal pressure.

Feel free of course to discuss and point out potential problems. I’m not going to vacuum test the charges. Jim Jarvis has done excellent research and testing with BP cannons. I’m currently comfortable with the above approach.

Thanks!

Chuck C.

Chuck, I think for Jim's testing to be relevant, you would have to maintain the same diameter to length ratio as he used.....and the tube sized according to the charge

 

[Rail Dawg]

Chuck, I think for Jim's testing to be relevant, you would have to maintain the same diameter to length ratio as he used.....and the tube sized according to the charge

Agreed Paul.

Dealing with G-12 makes the task easier because of it’s strength. I do plan to devote quite a bit of time testing the cannons and the actual separation of the rocket.

I’ll post some cool videos when that happens to gather some forum analysis.

Thanks.

Chuck C.

 

[boatgeek]

Agreed Paul.

Dealing with G-12 makes the task easier because of it’s strength. I do plan to devote quite a bit of time testing the cannons and the actual separation of the rocket.

I’ll post some cool videos when that happens to gather some forum analysis.

Thanks.

Chuck C.

If you have the opportunity when testing, it might be interesting to cool the outside of the apogee break coupler dramatically (dry ice?) to see what happens with some differential cooling. It's likely that the inside will be warmer than the outside at apogee because of [mumble mumble heat transfer mumble like I actually remember thermo from 20 years ago].

 

[Rail Dawg]

Hmmm you guys got me thinking lol.

I guess we could program one of the Marsa altimeter outputs to fire at a certain time or altitude AFTER apogee. Have a third backup charge cannon.

Have that charge be massive. Not enough to damage the rocket but enough to most definitely separate it lol. Like an emergency charge.

Chuck C.

 

[Ez2cDave]

If you have the opportunity when testing, it might be interesting to cool the outside of the apogee break coupler dramatically (dry ice?) to see what happens with some differential cooling. It's likely that the inside will be warmer than the outside at apogee because of [mumble mumble heat transfer mumble like I actually remember thermo from 20 years ago].

Hmm . . . I was thinking CO2 fire extinguishers to chill the airframe.

Dave F.

 

[Ez2cDave]

Hmmm you guys got me thinking lol.

I guess we could program one of the Marsa altimeter outputs to fire at a certain time or altitude AFTER apogee. Have a third backup charge cannon.

Have that charge be massive. Not enough to damage the rocket but enough to most definitely separate it lol. Like an emergency charge.

Chuck C.

Chuck,

Sound thinking . . . I like the idea of a "Doomsday Charge", if things "go South" !

Dave F.

 

[Theory]

Hmm . . . I was thinking CO2 fire extinguishers to chill the airframe.

Dave F.

View attachment 384612

that would be my approach. no matter what is chosen, having the test approximate the real world conditions as closely as possible is key

 

[ksaves2]

My line of thinking is sealed charge cannons.

BP in a black film canister with 2 electric matches. Extra space in canister filled with wadding.

(2) 38 mm G-12 cannons each with a film canister inside. Wadding filling the extra space there too. Top of cannon will be lightly sealed with epoxy. Upon ignition the BP should have enough volume to cause separation. Will of course ground test this to ensure G-12 can handle it. Will even triple the load to fully test the G-12 before putting into rocket for normal test.

Blow it up or blow it out. The rocket itself can handle significant internal pressure.

Feel free of course to discuss and point out potential problems. I’m not going to vacuum test the charges. Jim Jarvis has done excellent research and testing with BP cannons. I’m currently comfortable with the above approach.

Thanks!

Chuck C.

As I recall from my reading the trick was to keep the powder confined to facilitate complete burning. I think Jim outlined some well thought and tested methods to achieve that. Kurt

 

[Wallace]

Seriously doubt altitude (as far as charges) is gonna be your main concern. Getting a 50' chute to actually come out and deploy correctly is where I'd focus.

 

[boatgeek]

Sound thinking . . . I like the idea of a "Doomsday Charge", if things "go South" !

Another advantage of a doomsday charge is that it may give an auditory signal as to where the rocket is at 10K feet or wherever you set it. Not so much at 30K though.

Seriously doubt altitude (as far as charges) is gonna be your main concern. Getting a 50' chute to actually come out and deploy correctly is where I'd focus.

True dat.

 

[Rail Dawg]

As I recall from my reading the trick was to keep the powder confined to facilitate complete burning. I think Jim outlined some well thought and tested methods to achieve that. Kurt

Good point.

It’s why the charge will be packed in a film canister with wadding. The film canister will then be packed into the charge cannon again with wadding.

This comes directly from Jim’s research and suggestion.

Thanks!

Chuck C.

 

[Ez2cDave]

Another advantage of a doomsday charge is that it may give an auditory signal as to where the rocket is at 10K feet or wherever you set it.

Hmm . . . I hadn't considered that aspect . . . Perhaps, add a brightly colored smoke device, also ?

Dave F.

 

[Buddy Michaelson]

Good questions.

May end up with a filament-wound nose cone.

If not we'll beef up the inside of the current nose cone and strengthen the tip.

Going with a 50' Rocketman Pro-Ex parachute. Fortunately Buddy Michaelson at Rocketman will be at both LDRS and BALLS this year. He has offered to assist in the deployment bag packing of the parachute and recovery system.

So things are moving right along. Getting everything into place in just 5 months from receiving the rocket parts has been quite an effort. Thankfully there are guys like Pat G, the Engineering Dept, Levi Seaton and all the contributors to this thread to thank for this smooth process.

Chuck C.

Thank you so much Chuck, it’s a pleasure to work with you!! I’ll have to ask Tom Cohen how much black powder he uses, I would definitely go over kill, as the chute will weigh around 25lbs. How many charges do you plan to use? I’m thinking those 8 gram charge wells will be way too small personally but hard saying. Having a 5ft Chute on top of the bag will help tremendously to pull the main parachute out, but also to keep the bag hanging straight so the chute will pull out immediately. Tom can get my 60ft Chute out in a matter of a second which is exactly what you need to do. I look forward to meeting you and helping this year at Balls and LDRS to ensure a fantastic flight.

 

[jderimig]

I’ll have to ask Tom Cohen how much black powder he uses,

I heard ~140grams on his last flight. He doesn't mess around.