Merc..Crash and burn III

Onebadhawk
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That sure is a beautiful rocket with a failure to fly. Reminds me of early NASA footage. Is this a two or three engine cluster?
 
I have a two stage scratch built rocket that is currently in its fourth iteration.

The first two builds of this design crashed and burned. The second had a separation of the sustainer stage and its nose cone. The body fell straight down into tall corn, never to be seen again, while the nosecone and parachute went Dorothy Gale.

The forth build has flown successfully twice now and I’m not sure I want to push my luck any by flying it again.
 
Leo said:
Do you have the video without SME-music content?
Click to expand...

As I recall, the last video did not have music and featured mild "adult language," which actually added to my enjoyment and really made the video feel authentic!
 
ThirstyBarbarian said:
As I recall, the last video did not have music and featured mild "adult language," which actually added to my enjoyment and really made the video feel authentic!
Click to expand...

Do have a link to that version? I'd like to see the mercury flight.
 
Leo said:
Do you have the video without SME-music content?
Click to expand...

Really!!!! No music? Come on...Shot Down in Flames..the perfect song for such a flight, but any way..here ya go, just click on my avatar on Youtube and you can see all the videos of all flights..

[YOUTUBE]8mVG1xmSoE0[/YOUTUBE]

[YOUTUBE]ueAvkKhiZik[/YOUTUBE]
 
Thanks. Now I can see the content. Copyrighted material is blocked in many counties by Youtube.

It hurt watching the videos :(

Don't give up!
 
Leo said:
Thanks. Now I can see the content. Copyrighted material is blocked in many counties by Youtube.

It hurt watching the videos :(

Don't give up!
Click to expand...

AH...OK, now I get it..DUH, you're in Germany. What a coincidence, my wife's parents are here from Germany right now...yea, I married a Fraulein, smartest thing I ever did.

I will post another video W/O music though, just for those here out side the country.
 
OK As per request, the non music version, all natural sounds, the birds, the spitting, the cussing, the slinging of launch equipment, ect, ect.

[YOUTUBE]hl3GvaY4pIo[/YOUTUBE]
 
Man...that stinks!

What motors did you use?

Seems a bit more ns, maybe even an APCP motor with less of a delay...

Just thoughts off top my head, smarter folks here will have better for you I'm sure, just looks like a cool concept and would love to see it work for ya!!
 
You build great looking rockets but there are several issues to be resolved before you have a successful flight. One issue is the launch rod is way too short to obtain a stable vertical flight. The second issue is the average motor thrust is too low for the weight of the rocket. Unless significant change occurs, the rocket will crash every time it's launched. That's the harsh reality of physics. From your previous thread I believe the pad weight of the rocket was 29 oz. or 8 Newtons. A a minimum thrust to weight ratio of 5 is necessary to make the rocket work reliably, so a minimum of 40 N of vertical thrust is required. The the motors are canted, reducing the vertical thrust by the cosine of the angle off vertical. Assuming the angle is 45 degrees, only 70% of the thrust is in the vertical direction so 40 N/ 0.7 = 57 N of trust from the 3 engines or (3) E19 motors or greater is necessary. If the motors were each full E-impulse, the burn time would be 2 seconds. A conventional rocket would lift off the pad at 4 G net acceleration and reach a velocity of 4 g * 32 ft /sec - sec * 2 sec = 256 ft/sec assuming no drag, but the Mercury capsule has lots of drag, so the actual velocity will be less, but barely adequate for stable flight with a long launch rod or no wind. Without drag a conventional rocket would have a burnout altitude of ~256' with a maximum coast time =< 8 seconds, and apogee of ~=< 1280'. In reality, the terminal velocity of the Mercury capsule with an 18" diameter is ~33 ft/sec, and the maximum velocity under power with the minimum thrust engines I recommend provides 4 G net acceleration with a maximum powered velocity of ~66 ft/second. In reality with drag in a purely vertical flight you could expect a burnout altitude of ~115', and apogee of not more than ~175' or so at ~4 seconds with the recommended motors. You need E19-2 motors which do not exist, so you also need electronic deployment, and a 16' launch rod unless you launch in a dead calm. Houston will continue to have problems unless a major redesign occurs.... Sorry.
 
I do not see a fail here. The LES was intended to get the capsule away from a malfunctioning booster. Yours does, just not the way you want it to. If you were to build a booster to get it moving prior to firing the LES motors, it may work better. From a standstill, however, it definitely needs a bigger kick in the pants.
 
AS a follow-up to my earlier post, the actual Mercury capsule pad weight with tower and retro-pack mass was 1935 kg = 18.963 N weight. The tower rocket motor provided 231.5 kN thrust for 1 second for a T/W = 12.2. The initial vertical acceleration was 11.2 G and 11.9 G at burnout. Scaling it to your rocket, each motor would have 44 N thrust. https://www.braeunig.us/space/specs/mercury.htm (3) CTI Pro24 26E31 White Thunder or (3) CTI 24E22 Smokey Sam motors would provide enough thrust to make your rocket stable. (3) CTI Pro29 42F36 Smokey Sam motors would be just about scale with a 1.07 sec burn time. (3) CTI Pro29 57F59 White Thunder motors would allow you a bit more margin with weight but would also have a scale 0.96 second burn. They ignite quickly so cluster ignition would not be a problem. https://www.pro38.com/products.php
 
bobkrech said:
AS a follow-up to my earlier post, the actual Mercury capsule pad weight with tower and retro-pack mass was 1935 kg = 18.963 N weight. The tower rocket motor provided 231.5 kN thrust for 1 second for a T/W = 12.2. The initial vertical acceleration was 11.2 G and 11.9 G at burnout. Scaling it to your rocket, each motor would have 44 N thrust. https://www.braeunig.us/space/specs/mercury.htm (3) CTI Pro24 26E31 White Thunder or (3) CTI 24E22 Smokey Sam motors would provide enough thrust to make your rocket stable. (3) CTI Pro29 42F36 Smokey Sam motors would be just about scale with a 1.07 sec burn time. (3) CTI Pro29 57F59 White Thunder motors would allow you a bit more margin with weight but would also have a scale 0.96 second burn. They ignite quickly so cluster ignition would not be a problem. https://www.pro38.com/products.php
Click to expand...

Thanks for these posts Bob...these have been the most informative and detailed on engine thrusts and scale, this is what I've been needing. I've been mulling over the idea of a thrust structure rebuild of the tower and going to a reloadable 23mm or maybe even 29mm. The total, ready to fly weight is 29oz. There's been a lot of input from many, far more experienced, builders than I, and I take it all to heart. There's been a lot of discussion about size and weight, I've taken the advise and cut the weight considerably, but my thinking is, if the real thing can fly and deploy chutes than this one should be able to do the same. If I scale down then there isn't going to be enough room to accommodate 24mm engines, the set up is tight as it is now. If I scale down and go to 18mm then I'll be in the same boat I'm in now. I appreciate the time and input here.
 
I know on your other thread someone else also recommended composite 24 mm motors. I would think that would be a good route to take. The work in building the model is incredible. I would think that you would want to go to the more suitable motors, even though more expensive, before redesigning and re-building everything. One thing to keep in mind is that clustering of small 24 mm composite motors might be difficult. I would recommend using the Quest Q2G2 ignitors. Blue Thunder or White Lightning propellant should be easier to ignite (White Lightning might be the best). The cost would increase, but I would say do a test fire with a cluster of three 24 mm composite motors to see if you can get all of them to ignite simultaneously.
 
closet astronaut said:
Thanks for these posts Bob...these have been the most informative and detailed on engine thrusts and scale, this is what I've been needing. I've been mulling over the idea of a thrust structure rebuild of the tower and going to a reloadable 23mm or maybe even 29mm. The total, ready to fly weight is 29oz. There's been a lot of input from many, far more experienced, builders than I, and I take it all to heart. There's been a lot of discussion about size and weight, I've taken the advise and cut the weight considerably, but my thinking is, if the real thing can fly and deploy chutes than this one should be able to do the same. If I scale down then there isn't going to be enough room to accommodate 24mm engines, the set up is tight as it is now. If I scale down and go to 18mm then I'll be in the same boat I'm in now. I appreciate the time and input here.
Click to expand...
Black powder motors do not provide the thrust you need to become aerodynamically stable and to gain enough height for a safe recovery. Using Pro29 motors, and you need them versus the Pro24 motors or any smaller motors, will add 7 ounces more than (3) E12 motors, but it puts more mass forward to increase the stability. Three Pro29 1G 59F57-12A shortened by -9 seconds to a 3 second delay probably would be optimal. You might think about a mechanism that allows you to duct the ejection gases down hollow tower supports to pop the tower, and deploy a tower chute and a drogue chute to pull a d-bag with a main out of the capsule.
 

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