AT L-1000 DMS – flying case with a nose cone and 4 fins

[Theory]

This project is the definition of “next level!”

Unfortunately nothing that us East Coast guys can replicate locally

 

[rfjustin]

And to think if crew scheduling hadent moved my trip tonight.. I could’ve been supervising this little magic show tonight. Sigh.

There could have been beer... there could have been snacks! Next time brother, please.

 

[rfjustin]

Oh yeah, this cured up nicely.

 

[rfjustin]

Fillet are all done on the carbon one. Glass fin-to-fin will begin tomorrow.

 

[rfjustin]

Put a slight chamfer on the airframe tube and installed on the glass one.

 

[neil_w]

This is a great build, so very very far removed from the kind of stuff I do. I admire how much work is going into a single-use rocket. The tail cone was worth the price of admission alone.

 

[dhbarr]

This project is the definition of “next level!”

Unfortunately nothing that us East Coast guys can replicate locally

I205W?

 

[Rob702Martinez]

Can you tell us more about the coupler to the topnof the motor connection? Where did the potted epoxy go?

 

[rfjustin]

Can you tell us more about the coupler to the topnof the motor connection? Where did the potted epoxy go?

Gluing the coupler in place, mounting the bottom avionics plate with the thread rods attached, and passing the hex bolt into the top of the motor all happened in one step. Epoxy was sent down the side of the coupler from the top. These holes were not present by chance.

 

[rfjustin]

Can you tell us more about the coupler to the topnof the motor connection? Where did the potted epoxy go?

The plan was to send enough epoxy onto the plate to adhere it, but also purposfully allow epoxy to flow and partially fill the gap directly on top of the motor. IMO this strength is really needed to hold that coupler in place. The epoxy flowed through the holes and resides on top of the motor case now. I assure you the coupler cannot be removed at this point.

The rectangular yellow areas below represent where the epoxy "block" is now.

 

[Rob702Martinez]

Oh ok. So the coupler is part of the motor now but the bolt can be unscrewed and the bottom plate can come out?

 

[rfjustin]

Oh ok. So the coupler is part of the motor now but the bolt can be unscrewed and the bottom plate can come out?

No sir. What you see in the photos above is all permanent. That's the downside of single use. Still having a lot of fun with it though.

 

[crossfire]

No sir. What you see in the photos above is all permanent. That's the downside of single use. Still having a lot of fun with it though.

So the epoxy is on top side of bulk plate also?

 

[rfjustin]

So the epoxy is on top side of bulk plate also?

Yes, I would guess about 10% of the epoxy coated and remained on the top of the bulkhead plate. The other 90% or so flowed through the holes and "landed" on top of the motor, as designed.

 

[rfjustin]

Good seam...

 

[rfjustin]

 

[jd2cylman]

Awesome stuff as usual!

 

[BF Rockets]

Theory said:
This project is the definition of “next level!”

Unfortunately nothing that us East Coast guys can replicate locally

I205W?

I glued fins on a D12-7 back-in-the-day.

 

[neil_w]

View attachment 443264

Pardon my cluelessness: what am I looking at in the above picture? I can't figure it out.

 

[rfjustin]

Pardon my cluelessness: what am I looking at in the above picture? I can't figure it out.

Fiberglass cloth fin to fin reinforcement.

 

[neil_w]

Fiberglass cloth fin to fin reinforcement.

Thanks.

 

[CPUTommy]

View attachment 443264

Just awesome....love reading this thread!! The knowledge and skills are something everyone should strive to achieve. This project is awesome.

 

[rfjustin]

1 of 4, glass trimmed and light sand.

 

[mbeels]

Impressive rocketeering, pushing the limits of extreme performance. I'm curious though, how much advantage does going sub-MD have over MD? There is less wetted surface area, but with the addition of one transition (or two) in the diameter of the rocket. Is it over all a net gain in aerodynamics? Or just weight?

 

[rfjustin]

Since this is one is not true sub-minimum diameter, mainly weight.

 

[dhbarr]

Impressive rocketeering, pushing the limits of extreme performance. I'm curious though, how much advantage does going sub-MD have over MD? There is less wetted surface area, but with the addition of one transition (or two) in the diameter of the rocket. Is it over all a net gain in aerodynamics? Or just weight?

I seem to remember running some numbers on one of my tiny subsonic birds, so
but IIRC as long as your NC is fairly well optimized and your only widening is toward the tail, reduced cross section up front is always an improvement.

 

[rfjustin]

2 of 4 glass fin-to-fin done on the carbon one. More work to be done next week, after the Holidays...

 

[G_T]

Or flex enough to pop your o-ring seal by the nozzle...

Perhaps laminate a fillet of layers of glass to spread the bending load to a wider base. That will decrease case flex. Sort of a partial T-T.

By the way, if you introduce a thickness taper to your fins, thicker at the root and thinner at the tip, it will be much stiffer dynamically and have a higher flutter velocity. (PS - Just saw your last post. So this advice won't be worth much to you)

Go for it. I've been thinking of taking an 88mm EX O to Balls. M4 or a wee bit more. Machingbird. I've run lots of numbers on these sorts of rockets. One mach number per second of acceleration. The thing about fast little rockets is if they survive the boost, the climb gets easier as it goes! It just has to keep from softening from the heat until the dynamic pressure is low enough that it doesn't blow up, implode the nosecone, or shred. Whichever comes first! Single-use doesn't have to be reusable, just good enough to make the up part of the trip! If it is at 70Kft and smoking upwards, it no longer matters if the aluminum has been cooked, the high temp epoxy softened, or whatever. The rocket is getting much weaker, but the loads are also decreasing very rapidly. All just my opinion of course.

You can make a test flight by making a cylinder of aluminum to space a second hockey puck bulkhead, and test on a baby K propellant load perhaps. You (or somebody if you trust them) could make an EX motor to duplicate the thrust profile of your target motor but only for the first part of the burn then shuts off. IF it looks well behaved going through mach you might be good for the higher power attempt. But if it doesn't, it will very likely shred under higher power.

Gerald

 

[3stoogesrocketry]

You can make a test flight by making a cylinder of aluminum to space a second hockey puck bulkhead, and test on a baby K propellant load perhaps. You (or somebody if you trust them) could make an EX motor to duplicate the thrust profile of your target motor but only for the first part of the burn then shuts off. IF it looks well behaved going through mach you might be good for the higher power attempt. But if it doesn't, it will very likely shred under higher power.

Gerald
[/QUOTE]



SU 54mm motor . Its a full send flight.

 

[rfjustin]

You can make a test flight by making a cylinder of aluminum to space a second hockey puck bulkhead, and test on a baby K propellant load perhaps. You (or somebody if you trust them) could make an EX motor to duplicate the thrust profile of your target motor but only for the first part of the burn then shuts off. IF it looks well behaved going through mach you might be good for the higher power attempt. But if it doesn't, it will very likely shred under higher power.

Gerald

SU 54mm motor . Its a full send flight.
[/QUOTE]
I just like the idea naming a project "full send".....