Author Topic: ARCA (Read 152468 times)

xyv · « **Reply #360 on:** 03/25/2023 11:47 pm »

Eactly. It launches. We get it. How far did it go?

LouScheffer · « **Reply #361 on:** 03/26/2023 02:59 am »

Quote from: xyv on 03/25/2023 11:47 pm

Eactly. It launches. We get it. How far did it go?

I believe the answer is "not very far". If you watch the video from 0:15 to 0:22, you can see the rocket playing out a rather large cable that starts in "S" loops on the ground. The video ends exactly as this whole cable is played out. The cable is far too large to be telemetry, so I suspect it's a physical flight termination system to prevent it from leaving the range. In which case the greatest height achieved will be precisely the length of this cable, which looks at most like a few hundred meters.

Lampyridae · « **Reply #362 on:** 03/27/2023 10:43 am »

Quote from: LouScheffer on 03/26/2023 02:59 am

Quote from: xyv on 03/25/2023 11:47 pm
Eactly. It launches. We get it. How far did it go?
I believe the answer is "not very far". If you watch the video from 0:15 to 0:22, you can see the rocket playing out a rather large cable that starts in "S" loops on the ground. The video ends exactly as this whole cable is played out. The cable is far too large to be telemetry, so I suspect it's a physical flight termination system to prevent it from leaving the range. In which case the greatest height achieved will be precisely the length of this cable, which looks at most like a few hundred meters.

There are bottle rockets which have reached higher altitudes...

CameronD · « **Reply #363 on:** 03/31/2023 01:06 am »

Quote from: Lampyridae on 03/27/2023 10:43 am

There are bottle rockets which have reached higher altitudes...

Sure, but not ones this big.. to date, no-one has been crazy enough to try.

I wonder if they've thought of entering the UK competition? https://www.npl.co.uk/water-rockets It's only a few months to the next one and they might win a big teddy bear or something.

catdlr · « **Reply #364 on:** 03/31/2023 01:46 am »

Quote from: CameronD on 03/31/2023 01:06 am

Quote from: Lampyridae on 03/27/2023 10:43 am
There are bottle rockets which have reached higher altitudes...

Sure, but not ones this big.. to date, no-one has been crazy enough to try.

I wonder if they've thought of entering the UK competition? https://www.npl.co.uk/water-rockets It's only a few months to the next one and they might win a big teddy bear or something.

Wouldn't changing from pressurized H20 to mentos and coke give a higher ISP?

trimeta · « **Reply #365 on:** 03/31/2023 02:05 am »

Quote from: catdlr on 03/31/2023 01:46 am

Quote from: CameronD on 03/31/2023 01:06 am
Quote from: Lampyridae on 03/27/2023 10:43 am
There are bottle rockets which have reached higher altitudes...

Sure, but not ones this big.. to date, no-one has been crazy enough to try.

I wonder if they've thought of entering the UK competition? https://www.npl.co.uk/water-rockets It's only a few months to the next one and they might win a big teddy bear or something.

Wouldn't changing from pressurized H20 to mentos and coke give a higher ISP?

In fairness, they don't use pressurized H2O...they use superheated H2O which then undergoes a phase change into a gas. It's a tea kettle, not a stomp rocket.

I don't know the Isp of mentocoke rockets, though.

matthewkantar · « **Reply #366 on:** 03/31/2023 02:19 am »

I remember hearing Isp of -1.5 for Mentos/Coke propulsion. Not sure if that was vacuum or sea level.

catdlr · « **Reply #367 on:** 03/31/2023 02:26 am »

Quote from: matthewkantar on 03/31/2023 02:19 am

I remember hearing Isp of -1.5 for Mentos/Coke propulsion. Not sure if that was vacuum or sea level.

Thanks, just having some fun.

JCRM · « **Reply #368 on:** 03/31/2023 08:10 am »

Quote from: matthewkantar on 03/31/2023 02:19 am

I remember hearing Isp of -1.5 for Mentos/Coke propulsion. Not sure if that was vacuum or sea level.

I very much doubt it was negative

Nomadd · « **Reply #369 on:** 03/31/2023 08:11 am »

Quote from: JCRM on 03/31/2023 08:10 am

Quote from: matthewkantar on 03/31/2023 02:19 am
I remember hearing Isp of -1.5 for Mentos/Coke propulsion. Not sure if that was vacuum or sea level.
I very much doubt it was negative

Negative ISP is fine. You just turn the rocket upside down.

matthewkantar · « **Reply #370 on:** 03/31/2023 03:33 pm »

I meant to put a ~ in there, not sure how I ended up with a minus sign.

Edit: Negative Isp would really suck.

Steven Pietrobon · « **Reply #371 on:** 04/01/2023 04:14 am »

Quote from: matthewkantar on 03/31/2023 03:33 pm

I meant to put a ~ in there, not sure how I ended up with a minus sign.

Edit: Negative Isp would really suck.

Negative Isp could mean that the thrust is opposite, which is not a problem since you would just launch upside down or propellant flow is negative, which just means you lift off with empty tanks which fill up on the way to orbit! :-)

edzieba · « **Reply #372 on:** 04/03/2023 08:54 am »

Quote from: Steven Pietrobon on 04/01/2023 04:14 am

Quote from: matthewkantar on 03/31/2023 03:33 pm
I meant to put a ~ in there, not sure how I ended up with a minus sign.

Edit: Negative Isp would really suck.

Negative Isp could mean that the thrust is opposite, which is not a problem since you would just launch upside down or propellant flow is negative, which just means you lift off with empty tanks which fill up on the way to orbit! :-)

An evacuated tank with an open top end. Negative ISP, and very little actual impulse. At least we know what Arca can pivot to next!

catdlr · « **Reply #373 on:** 06/27/2023 10:08 pm »

Looks like another Water Deluge test is coming soon....

EcoRocket: Episode 20 - EcoRocket Heavy, First Modules

Quote

Jun 27, 2023
The first modules for the EcoRocket Heavy were lifted into a vertical position at the Cosmobase.
EcoRocket Heavy is designed to transport the AMI spacecraft into orbit for asteroid mining operations starting in 2027.

xyv · « **Reply #374 on:** 06/28/2023 02:22 am »

Oh my

. They have gone full on "mouse that roared". Maybe somebody feels like sizing that rope (yes...rope!) or those square tube "lifting bars". That thing would be light by Hollywod movie prop standards.

catdlr · « **Reply #375 on:** 06/28/2023 03:11 am »

Quote from: xyv on 06/28/2023 02:22 am

Oh my . They have gone full on "mouse that roared". Maybe somebody feels like sizing that rope (yes...rope!) or those square tube "lifting bars". That thing would be light by Hollywod movie prop standards.

Steven they're empty...

daedalus1 · « **Reply #376 on:** 06/28/2023 06:12 am »

Modified oil, gas or water pipeline. Looks nice anyway.

Asteroza · « **Reply #377 on:** 06/28/2023 08:00 am »

Quote from: daedalus1 on 06/28/2023 06:12 am

Modified oil, gas or water pipeline. Looks nice anyway.

I'm half inclined to think it's paper mache...

but probably fiberglass...

catdlr · « **Reply #378 on:** 06/28/2023 08:05 am »

Quote from: Asteroza on 06/28/2023 08:00 am

Quote from: daedalus1 on 06/28/2023 06:12 am
Modified oil, gas or water pipeline. Looks nice anyway.

I'm half inclined to think it's paper mache...

but probably fiberglass...

Yes, it's probably being hoisted into his "Rocket Garden" display of proposed rockets that he wants investors to view. It's all show.

CameronD · « **Reply #379 on:** 06/29/2023 04:22 am »

Quote from: Asteroza on 06/28/2023 08:00 am

Quote from: daedalus1 on 06/28/2023 06:12 am
Modified oil, gas or water pipeline. Looks nice anyway.

I'm half inclined to think it's paper mache...

but probably fiberglass...

Gotta love the mold line.. I guess that's a designed in part of their FTS?