A Rocket That Launches Attached To A Horizontal Track That Transitions To Vertical

[lakeroadster]

That said I'd like to see your final product with a 5 degree off vertical final ramp angle so your rocket (and possible sled) can be aimed in the safest direction for your launch site.

That's easily doable. Lifting the "Starting Line" of the track 5 degrees will cant the "Exit Line" of the track 5 degrees.

 

[lakeroadster]

2020-03-27 Updated drawing set: Rocket Sled Dwg, Rev 05, Sheets 1 through 8

 

[lakeroadster]

And here's some screen shots..

 

[prfesser]

I am not so sure about that. If I understand my physics right, if you swing a ball on a rope, and suddenly release the rope, the ball will continue on a straight trajectory on the exact heading it was on when you released it.

Where is @prfesser when you need him?

"Dammit, Jim, I'm a chemist, not a physicist!?

 

[lakeroadster]

Turned the nose cone and the transition for the RS-R (Rocket Sled - Rocket) today. Made from Southern Yellow Pine

Life is good. I just love designing and then making stuff.

 

[lakeroadster]

2020-03-27 Update: Rocket Sled Rocket Drawing Rev 04 Sheets 1 through 10

 

[lakeroadster]

Made some centering rings and another transition using my new Nova G3 Chuck for my wood lathe.

Made these from ash. I'm learning that pine just doesn't work well, it's so soft that it's problematic to cut and for parts like centering rings it doesn't have the strength needed for making delicate thin wall parts.

 

[lakeroadster]

I did some mandrel turning on the wood lathe today .... learned this technique from a guy over on the American Association of Woodturners website.

It allows you to turn pretty precise, delicate parts and keep the bore concentric with the outer profiles. The transition I made has a wall thickness of 0.070... Trying to turn it without the mandrel just didn't work very well..

I was surprised that with just a friction fit that I could still use chisels to turn the part.

 

[Greg Furtman]

I did some mandrel turning on the wood lathe today .... learned this technique from a guy over on the American Association of Woodturners website.

It allows you to turn pretty precise, delicate parts and keep the bore concentric with the outer profiles. The transition I made has a wall thickness of 0.070... Trying to turn it without the mandrel just didn't work very well..

I was surprised that with just a friction fit that I could still use chisels to turn the part.

View attachment 409466 View attachment 409463 View attachment 409467 View attachment 409468 View attachment 409464 View attachment 409465 View attachment 409469

John, after using my Nova G3 yesterday I have come to a conclusion. You are a good influence. I really like the G3!

 

[bibbster]

John, what type of lathe do you have? And would you recommend it? And to a beginner?

 

[Greg Furtman]

John, what type of lathe do you have? And would you recommend it? And to a beginner?

@bibbster I think this would be a good beginning lathe. Made by the same company, Teknatool, that makes the Nova G3 chuck & jaws that John & I bought. In fact it comes with the G3 chuck & jaws. Plus it comes with some turning chisels.

https://www.amazon.com/Teknatool-T3...=1&keywords=wood+lathe&qid=1584630169&sr=8-18

 

[bibbster]

Thank you, John!

 

[Greg Furtman]

Thank you, John!

Who?

 

[bibbster]

Doh! Where did I get John? Must be all the hand sanitizer. Lol

 

[lakeroadster]

John, what type of lathe do you have? And would you recommend it? And to a beginner?

I have a Jet JWL-1236 that I bought exactly a year ago, used, for $200. I would indeed recommend it.

I wouldn't buy new when you can get a good used one, for less money, and better capacity. At least that's my take. Just be sure to inspect it well and ask the owner to demonstrate it, putting it through it's paces, before you buy it.

 

[bibbster]

That's where I got John from! Ahem. Thank you, John.

 

[Culprit]

I just found this thread - possibly while on a 3 hour conference call while working from home during the quarantine.

I am intrigued.

The mass of the booster stage with motor is hanging off the rear end of the rocket - that may be a hefty moment of inertial as the rocket turns the corner on the rail held in place by the body tube friction fit. Imagine holding the rocket with your arm straight out in front of you parallel to the deck and twisting your wrist sharply so the rocket moves from horizontal to vertical. How much force can the booster stage handle without twisting off, or cocking to the side? A larger shoulder interface between the booster and sustainer stages may be beneficial.

PS: Lakeroadster - you turn pine for fun? You're sick and twisted. I'm a fellow Nova G3 user, but on a 1955 Shopsmith that I rewired the motor to be reversible to help with sanding. I use the mandrel method also.

I can't wait to see you fix your little problems and light that candle!

 

[John Beans]

Fun project to make and watch. Safely done, it would definitely add a degree of drama to the launch, which is always cool.

Even though it's less efficient than a normal rocket launch (and that's probably not the point of the whole thing anyway, I know). The only physics reason to do this would be if you could somehow dodge the rocket equation while it's on the ground.

Ways to dodge the rocket equation:

• A magnetic rail gun driver
• A power tension catapult like on an aircraft carrier
• A bungee, like they use for launching gliders
• A traction motor against the track (a geared track would be very efficient)
• Using a pressure piston (like people already to for competitions)

But if you use a rocket motor for the horizontal part then you're not gaining anything, even if there's a downhill section. Whatever energy you use on the track would be better spend going up—including just considering a longer launch rail/rod for stability.
But again—not that physics is the point.

Fun? Yes! That's the soul of model rocketry.

 

[lakeroadster]

I just found this thread - possibly while on a 3 hour conference call while working from home during the quarantine.

I am intrigued.

Glad I could help Welcome to the thread!

Be sure and check my other links in my signature line below.

The mass of the booster stage with motor is hanging off the rear end of the rocket - that may be a hefty moment of inertial as the rocket turns the corner on the rail held in place by the body tube friction fit. Imagine holding the rocket with your arm straight out in front of you parallel to the deck and twisting your wrist sharply so the rocket moves from horizontal to vertical. How much force can the booster stage handle without twisting off, or cocking to the side? A larger shoulder interface between the booster and sustainer stages may be beneficial.

Good point. My original plan was a battery pack on the sled to ignite the rocket motor. It was pointed out that per Association rules that wasn't legit.

But your point is only valid if the speed of the rocket / sled is high... until I do some testing I'm not sure that will be the case.

look at the fin alignment between the booster and sustainer fins. That will add some support. I could also add a saddlle (attached to the sled) to cradle the bottom of the booster.

Testing should be fun....

PS: Lakeroadster - you turn pine for fun? You're sick and twisted. I'm a fellow Nova G3 user, but on a 1955 Shopsmith that I rewired the motor to be reversible to help with sanding. I use the mandrel method also.

Yeah... pine can be challenging to turn on a lathe. Hardwoods are a piece a cake. I've leaned for big parts like nose cones pine works great. But for thin wall parts like transitions and centering rings hardwoods are required.

I can't wait to see you fix your little problems and light that candle!

Thanks.

 

[Alan15578]

Fun project to make and watch. Safely done, it would definitely add a degree of drama to the launch, which is always cool.

Even though it's less efficient than a normal rocket launch (and that's probably not the point of the whole thing anyway, I know). The only physics reason to do this would be if you could somehow dodge the rocket equation while it's on the ground.

Ways to dodge the rocket equation:

• A magnetic rail gun driver
• A power tension catapult like on an aircraft carrier
• A bungee, like they use for launching gliders
• A traction motor against the track (a geared track would be very efficient)
• Using a pressure piston (like people already to for competitions)

But if you use a rocket motor for the horizontal part then you're not gaining anything, even if there's a downhill section. Whatever energy you use on the track would be better spend going up—including just considering a longer launch rail/rod for stability.
But again—not that physics is the point.

Fun? Yes! That's the soul of model rocketry.

However, if you have thrust less than weight, the vertical launch gets you nowhere. You can still accelerate horizontally to say, optimal velocity, and then bend your velocity vector upwards. There can be some merit to horizontal launch, but as a practical matter, near vertical launch wins.

 

[jqavins]

Darn you! Now I want to build a rail gun pre ignition accelerator.

 

[lakeroadster]

Stuff that bothers ya....

When I turned the transition in my wood lathe I left a flat area where the BT-60 tube attached to it. The more I looked at it the less I liked it. So I took the transition and re-machined it to not have a flat.

Night and day difference IMO.

What do you think?

(Embrace the spirals... )

 

[jqavins]

If you're going to paint the transition and booster tube the same then barely matters. I like the reduced slope a little bitter, but I do mean a little.

If you're going to leave it visible, or for that matter if the paint scheme leaves the separates parts visible, then I'm sorry but I like the original better.

Incidentally, it looks like a rifle round.

 

[lakeroadster]

If you're going to paint the transition and booster tube the same then barely matters. I like the reduced slope a little bitter, but I do mean a little.

If you're going to leave it visible, or for that matter if the paint scheme leaves the separates parts visible, then I'm sorry but I like the original better.

Incidentally, it looks like a rifle round.

Thanks for the reply... No need write "sorry"... it's all good.

So maybe the rocket should be named "Bullet" or "120 Cal", after all, it's already got rifling.

 

[lakeroadster]

Snuck down the hill today and bought some basswood.

Cut the body tube for the fins, and cut the 1/8" basswood on my scrollsaw.

I've become a true believer in the through wall fin design... snaps together like some sort of mass produced kit.

 

[lakeroadster]

Assembled / glued the fin can and transition and installed the launch lugs. Now... ye ole time honored process of glue fillets.

 

[jimzcatz]

I can't believe you are supporting this. This us plainly against any and all safety codes. ANYTHING, and I repeat ANYTHING propelled along a horizontal path is against the coded. No ifs and or buts. Plain and simple. No gray area. The fact that you can't get that through your "hold my beer" heads blows my mind. Even on private property its a bad idea should something wrong happen and the public get involved. Unbelievable.

 

[Culprit]

“ANYTHING, and I repeat ANYTHING propelled along a horizontal path is against the coded. No ifs and or buts. Plain and simple. No gray area.” - jimzcatz

Estes:

 

[lakeroadster]

I can't believe you are supporting this. This us plainly against any and all safety codes. ANYTHING, and I repeat ANYTHING propelled along a horizontal path is against the coded. No ifs and or buts. Plain and simple. No gray area. The fact that you can't get that through your "hold my beer" heads blows my mind. Even on private property its a bad idea should something wrong happen and the public get involved. Unbelievable.

Jim, I don't even drink beer.


The rocket powered sled never leaves the track.

The rocket doesn't leave the track until it is vertical.

We had this discussion starting back on post #1

 

[lakeroadster]

More build photo's.

Installed the dual launch lug reinforcing bars and started laying down the Quick and Thick.

The re-bars are needed since the lugs are the primary constraints for the rocket until it is cut loose from the sled.