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Discussion in 'Scratch Built' started by lakeroadster, Feb 16, 2020.
Heavy Metal up front! Weight on hinny is sinful!
A D12-5 and a D12-7 will be utilized.... that will minimize the chance of both barrels firing simultaneously... and provide a backup.
I'll pull up the CAD model and see what I can do to get a less restrictive ejection gas flow pattern. And I can also bend up some aluminum thin gauge sheet installed inside to protect the top of the head from the blast.
I could also add some obnoxiously large 3-4-5 triangles or some circle templates (aka fins), installed perpendicular to the head, on that strap on ballast. At least for the 1st flight.
Food for thought (Not mindsim!) D12 0s by themselves could provide enough pressure to push out the chute and wadding??? Not like you need lots of delay and it will take awhile for everything to deploy from the box.
Wait, are you saying fins in the opposite plane up top? It seems to me that would be the opposite of helpful. You could use four fins at the bottom, and you could even make them four different shapes: a triangle, a circle template, a French curve, and another template such as flow chart or electrical symbols.
Also, from what I think I remember from my (thankfully) brief and distant drafting days, wouldn't 30-60-90 triangles be more appropriate than 3-4-5?
(Now I'm thinking of building it and making sure it CATOs spectacularly; I hated drafting.)
The fins would be on the strap on ballast at the bottom of the blade.
Actually, that's the BIG "sin" here. In a "normal" rocket any sideways thrust is countered by the fins. But this design has no fin surface perpendicular to the direction of thrust.
You have made your point.....
The Jedi have launched finnless rockets for a thousand years. Clear your mind, focus on where you are at and what you are doing. Use the force and feel the energy between you and the thrust, the gravity and the airflow over the rocket. Upward inertia off the rail is your friend, calm air above is your friend. Use the canted tractor motors to fly the rockets you love. Feel the power and ignore what some may call unnatural. Fly the T Square and your journey to the oddrocs will be complete. Once the oddroc path is chosen forever will it guide your destiny.
Remember that Kahn thought a little two dimensionality but was still able to kick Kirk's hinny!
Has the added benefit of not going very far before deployment, alway a plus when stability fails to be nominal.
Actually having recently rewatched ST-II, the Wrath of Khan, it was Khan’s two dimensional thinking that allowed Jim to take him out in the cloud. Spock didn’t fair so well, he had to go through puberty again before he became a real character.
That is the irony! If the rocket catches an unfortunate gust of wind then only thing to do is scream like Kirk trapped in the asteroid.
If the rocket catches an unfortunate gust of wind the only thing to do is have the RSO call for a duck and cover!
Yep. It is rear eject and with tightly packed chutes that take awhile to unfurl it might work. Would avoid scary ejection charges while still using motor ejection. Lower pressure easier to deal with.
Just like the ChiComm rocket that took out that nearby Village.
If it goes airplane or land snake at least it is a nice flat rocket with a reinforced leading edge. The Bards can sing of ye ole flying T Square of death.
The Jedi have the advantage of the Lucas-Force (aka sci-fi Hollywood special effects.)
“You don’t neeeeed (to obey the laws of aerodynamics)”
“You don’t neeeed (to obey the laws of basic physics)”
The Jedi wannabes cheat, sometimes successfully, substituting lots of thrust and lots of nose weight and base drag for the mystical Lucas-Force.
Keep those eels away from your ears guys......
I spent some time on the CAD model today.. changed the shape of the head a bit so the ejection forces have a nice free flowing channel instead of small slots.
Also did a study of adding some 30-60-90 drafting triangles (fins) on the blade...
I like it better with out the fins.
Interested in the results of your unorthodox ejection system. I had roughed out something similar for the front of an Avro Lancaster or B17 bomber, with the chute coming out of the bomb bay doors. I was going to redirect the gases from a C6 0 through a channel of epoxy clay.
Orthodoxy would keep you on the straight and narrow ejection path. A 180 degree redirect bend definitely puts this in the unorthodox category!
"Ye Ole Bench Test" should reveal any issues. But it may very well shred the head. Or the hot gases might burn it up?
I'm surprised that nobody has any actual numbers showing ejection forces for various motors. Folks "drill down" on the numbers for everything in this hobby.... except that?
I think I will find the Lucas Force if I buy that '96 Jaguar xjs convertible a few blocks over.
You just need to bend the basic laws as far as possible. It is the quick and easy way to power. Then you will gain that true sense of self satisfaction.
Many times I have seen the padawan successfully silly things using the oddroc friends of power, nose weight, canted motors, drag offsets for asymmetry, streamer tails and ridiculous base drag to name a few. But I do like to say Power and Nose weight are just a crutch and should not be used to cover up silly design. With lots of good bobblehead agreement I then pull out my next build for club preinspection.
They are out there but there are variables in mass produced single use back powder motors. You really need to come by and chat with the top high power men and pyros. They will talk for days on the subject of ejection charges.
The Tripoli Colorado dinner is Feb 22 in Northglenn. Check out their website. I will really try to make it, especially if I can hang out with some oddrocketeers!
Does it come with a tow truck?
Nobody kicked anybody's hinny in that movie. That would have been pointless and cruel.
And not only did Khan's 2D thinking allow Kirk to beat him in the nebula, Kirk did it by firing shots right up Khan's hiney. (Well, OK, Chekov fired the shots up Reliant's hiney, but let's no quibble.)
To send this further into the weeds: I recently saw Wrath of Khan at our local performing arts center, followed by a sit-down interview with William Shatner. Three observations:
1) What a great, great movie. It had probably been multiple decades since my last viewing.
2) Shatner is getting old
3) Shatner is a very entertaining guy. He's just like you'd expect him to be.
Curious why they would have the dinner in February in Colorado... and on a Saturday when the highways are gridlock from all the snow bunnies? For the last decade in Colorado, February has been the snowiest month of the year.
I mean... looking at historical snowfall data isn't "Rocket Science"...
Ain't no snow bunnies gonna stop the good ole boys from that delicious all you can eat Italian buffet! They know the back ways to the dinner. It's a once a year chance to get cool stuff at the raffle and talk non stop rockets!
Well, with all due respect, that works for you Front Range Flatlanders.
Golly, now I am all triggered and will need time in one of the Corporate safe rooms up on the 9th floor with a therapy dog. These darn phones put in all kinds of words. Good thing I didn't use the word ass as this is family forum! Such two dimensional thinking and rocket flying is just way too dangerous, must run and hide. Going to watch angry new Spock kick new Kahn's hiney to bring me down while in the safe area with the puppy.
It's bigger and now it's got exhaust headers!
Went back to the drawing board and increased the size of the model to allow use of some copper close radius pipe elbows to redirect the exhaust gasses.
The Open Rocket simulation was unstable until I lengthened the blade to 33-1/2" and added 8 oz of ballast to the bottom. Now she's right near purty again.
If I use Aerotek motors I could have used much smaller header pipes and probably gotten away with the previous T-Square model size, since the ejection nozzles are smaller on the Aerotech motors... but the D12's are more economical and a bigger rocket is mo 'betta. That being said... at a 222 ft apogee on D12's I'm not sure that will be enough altitude for the chutes to fully blossom?
What do you think?
Definitely like the triangles at the bottom!
Not sure I understand adding 8 oz ballast to BOTTOM, I am not an open rocket guy, but seems counterintuitive.
Amazing drawings, although for you that is par for the course, as my Dad says.
I bet it's so draggy that it'll be fine, provided you fly it on a grassy field.
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