Mach 3.5 Loki L Altitude Record Attempt Build

Dipstick

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That was almost like the N10 000 vmax speed liftoffs! Beautiful!
 

grouch

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I mean the flight was cool and all but what I really want to know about is that hat you are wearing. Please tell me more!
 

watheyak

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Any thoughts on an M1378 flight?
Also I second the question about the M1378 flight.
Probably not an M1378 at this time. This this rocket will enjoy an early retirement, hung on the wall of my rocket room. Next on the list is a similarly constructed rocket, but 4" and a longburn motor for Balls.

How’s the GPS altitude data look?
It jives with the altimeter data. The Featherweight Tracker gave good data during the flight and was broadcast over the launch PA system. It took us right to the rocket after landing. Great system, as easy as it gets. I have yet to make a fancy KML file. I'll get to that.

I mean the flight was cool and all but what I really want to know about is that hat you are wearing. Please tell me more!
Wearing outrageous hats gets you places in our club.

It's actually a neato backpacking hat by Kavu, with a bit of Big Trouble in Little China flair.

Screenshot 2021-03-02 134822.png
 

watheyak

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First off, I’ve received official word from the records committee that the record has been approved! Super stoked! I’ve been wanting to make this rocket and set this record since Kosdon L3000s were a thing. The technology and resources just took this long to come together.

It should be posted on the records page soon!

If you were to rebuild a similar rocket, is there anything you would change or make differently?

If I were to do this again it would be much simpler. I stated at the beginning of this thread that there were things done in this build that were over the top, overly complicated, and overly flashy. Some of that was done to test build methods (fin tip to tip), others just for some cool factor (Kevlar nose cone).

So for one, I’d do simple plate fins and a healthy fillet from high-temp Hysol epoxy or similar, with no tip to tip. Also, after thinking about it, I’m never doing a short fincan and motor diameter nosecone again. After seeing what the shockwaves did at every minor imperfection, I don’t think it makes sense aerodynamically. And it drastically increases structural complexity. Fincans are sooooo 2019.

The next project is the 4” version of this. It has a thin wall tube made by REK that will be just short of the length of the motor case, using the forward few inches of the motor case as the nosecone coupler. As short as possible, and constant diameter. There will also be a custom, high temperature nosecone to match the tube diameter.


What accounts for the large difference between accel altitude and baro altitude? Which do you believe to be correct?

Upper level winds. They were high. There was a shear layer up there where you can see the rocket make a left turn as it passes that altitude. In hindsight I maybe could have waited for better upper level winds.

I’ve also been pondering launch tower angles and high altitude rockets.

I trust the baro and GPS altitudes.

That’s it for now. On to the 4” Balls project. Thanks for watching everybody! I definitely appreciated the help, encouragement and compliments.
 
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plugger

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Also, after thinking about it, I’m never doing a short fincan and motor diameter nosecone again. After seeing what the shockwaves did at every minor imperfection, I don’t think it makes sense aerodynamically. And it drastically increases structural complexity. Fincans are sooooo 2019.
Yep, I feel the same way. I've always wondered if there was a net benefit for altitude shots with a flying case/fincan design given the added drag of the larger diameter fincan combined with the drag effects of the quite brutal 'step' the fincan has when compared to a VK NC that is flush to the rest of the airframe.
 

AeroAggie

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I feel I left enough altitude on the table to encourage challengers. Bring it! I’d love to see someone beat it.

Maybe someone this weekend 😉
I think you did too. I have parts on the work bench and a simulation, but work and life have conspired to delay combining those. I hope to start the build very soon with a target of late summer test flights and a record attempt at Argonia later. The field elevation won't help me there, but at least I can calibrate my sim and tweak before going to Black Rock or some other venue for a real attempt.
 

dvdsnyd

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So for one, I’d do simple plate fins and a healthy fillet from high-temp Hysol epoxy or similar, with no tip to tip. Also, after thinking about it, I’m never doing a short fincan and motor diameter nosecone again. After seeing what the shockwaves did at every minor imperfection, I don’t think it makes sense aerodynamically. And it drastically increases structural complexity. Fincans are sooooo 2019.

Congrats on the successful project and record! I'm really interested in your approach for simplifying the fins. Will this be showcased in your 4" version?
Dave
 

GrouchoDuke

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I can't believe that was the only pic I had of me holding the rocket.
I hear ya. I added “get pix of me with the rocket” to my record attempt checklist. On my last one, I just did a selfie while prepping at the pad. Fun stuff!
 

Kip_Daugirdas

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The next project is the 4” version of this. It has a thin wall tube made by REK that will be just short of the length of the motor case, using the forward few inches of the motor case as the nosecone coupler. As short as possible, and constant diameter. There will also be a custom, high temperature nosecone to match the tube diameter.

Congrats on the record! I love the work you did on this project. Super slick, I may borrow some ideas ;)

In terms of using the forward end of the casing as a coupler are you at all worried about it heating up and binding with the composite recovery section?
I’m only bringing it up because this was my plan on a new project. I static tested the motor last weekend and despite my best efforts to insulate things, the casing still heated up to ~150F at the forward closure. On a 3” case that’s about .003” of growth on the diameter.

I love super tight slip fits as I’m sure you do too. I’m still uncertain if I could accommodate the thermal expansion of the case. Some tests are definitely in order...
 

watheyak

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Congrats on the record! I love the work you did on this project. Super slick, I may borrow some ideas ;)

In terms of using the forward end of the casing as a coupler are you at all worried about it heating up and binding with the composite recovery section?
I’m only bringing it up because this was my plan on a new project. I static tested the motor last weekend and despite my best efforts to insulate things, the casing still heated up to ~150F at the forward closure. On a 3” case that’s about .003” of growth on the diameter.

I love super tight slip fits as I’m sure you do too. I’m still uncertain if I could accommodate the thermal expansion of the case. Some tests are definitely in order...

Thanks Kip!

The coupler that went around the forward closure was crazy thick, a little more than 5/16" wall thickness. I wasn't so concerned with thermal expansion from the motor burn, but Arizona heat and dust. It was a tight slip fit, plus I lubricated the joint. But I can't for the life of me remember what I used.

I'm working on a 4" version of this that uses the forward ~4" of the motor case as the coupler. I'm hoping to get around motor expansion related fit issues with Teflon tape around the motor case at the base of the nosecone for a snug fit, and a Delrin disc as the front end of the coupler for low friction, minimal points of contact, but maximum stability. If that makes any sense....

Screenshot 2021-05-20 231046.png

IMG-2430.jpg
 

dhbarr

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How much will the NC expand at that speed? I suppose it will also cool pretty rapidly at coast, so maybe better just to ignore.
 

mrwalsh85

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Hi Scott,

Congratulations on your flight. Phenomenal performance. I dream one day that I will find the time to mess around with composites in this manner.

I am curious - can you share information on your forward closure eye bolt? I'd like to get some.

thanks,
Mike Walsh
 

Kip_Daugirdas

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Thanks Kip!

The coupler that went around the forward closure was crazy thick, a little more than 5/16" wall thickness. I wasn't so concerned with thermal expansion from the motor burn, but Arizona heat and dust. It was a tight slip fit, plus I lubricated the joint. But I can't for the life of me remember what I used.

I'm working on a 4" version of this that uses the forward ~4" of the motor case as the coupler. I'm hoping to get around motor expansion related fit issues with Teflon tape around the motor case at the base of the nosecone for a snug fit, and a Delrin disc as the front end of the coupler for low friction, minimal points of contact, but maximum stability. If that makes any sense....

View attachment 465292

View attachment 465293
Ya that looks good! You benefit from using the tapered portion of the nose cone. And commercial cases are well undersized from airframe/nosecone IDs which lets the bottom of the nosecone shoulder ride on the PTFE tape. Its got plenty of clearance on the rest of its length and should separate easily

Your lucky - I wish could have this setup but unfortunately I can’t stuff everything I want to fly into the nosecone.

@mrwalsh85 it’s a flat-shoulder rod end bolt. Search for that in McMaster. There’s a lot of “not for lifting” rope guides/rod ends that work awesome for recovery hard points on small and light 2/3/4”rockets.
 

mrwalsh85

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@mrwalsh85 it’s a flat-shoulder rod end bolt. Search for that in McMaster. There’s a lot of “not for lifting” rope guides/rod ends that work awesome for recovery hard points on small and light 2/3/4”rockets.

That "not for lifting" is what has been steering me away from those. LOL

Thanks for the note. Will have to look into those. I have several min dia projects in the immediate queue and these will help!
 

watheyak

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That "not for lifting" is what has been steering me away from those. LOL

Thanks for the note. Will have to look into those. I have several min dia projects in the immediate queue and these will help!

I think @rfjustin broke one overtightening it a while back, but I still think they're plenty strong enough. There's black oxide and SS versions.


 

rfjustin

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I think @rfjustin broke one overtightening it a while back, but I still think they're plenty strong enough. There's black oxide and SS versions.


IMO, you will break your recovery cordage before you break a Solid Rod End.

Just my .02 YMMV.... :headspinning:
 

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