How about a More Curvilinear Warlock?

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ThirstyBarbarian

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I recently decided to get an LOC Warlock. I wanted something I could fly on H and I motors that would not go too high. The weight of the Warlock is right for many H and I motors, and the draggy 7.5" airframe should keep it pretty low. And then I got an idea that I think could be interesting.

This is what an Estes Curvilinear looks like:


Estes-Curvilinear-Model-Rocket.jpg



I think the Curvilinear is a cool-looking rocket. It's s small rocket for 13mm A10-3 engines. The proportions are very similar to the Warlock's, so I thought you could probably add a similar ring fin (if that is the right term) to a Warlock for a cool Sci-Fi look. Here's the basic idea.


Warlock-tube-fin.jpg


It's not exactly to scale with the Curvilinear, because the ring on the Warlock would have to be big enough for a rail to fit between the airframe and the ring fin. This example above shows a ring that is 11" in diameter to give about 1.5" clearance, and scale would be closer to 9", which would not have enough clearance. The Curvilinear is also a 4-fin rocket, while the Warlock is 3. So this would not be a true Curvilinear upscale, more of a Curvilinear-inspired Warlock.

This is just an idea I've been mulling over, not something I'm committed to doing. I want to keep it flyable on L1 motors, so this might add enough weight and drag that it would move more into the L2 range, in which case I would not do it. I had a similar issue with the pod rocket modifications I made to a Mega Der Red Max --- it is kind of heavy and draggy for G motors now, and the weight is what forced me to certify for L1. I don't want something similar to happen where I'd have to get an L2 just to fly the modified rocket!

Any feedback on the design is welcome!

What do you think of the proportions of the ring? Right now, the ring has an 11" diameter, and I'm not even sure sonotube or other kinds of large tubing comes in exactly 11" diameter. My feeling from playing with different diameters was that smaller was aesthetically better than larger, as long as the rail can pass through. So if the rail could pass through a 10" ring, that would look better that going to a 12" ring.

Also, the ring length shown in the example, is 5", which is half the length of the fin root. 6" looks pretty good too. As you go up in length, after a point, it gets too long and doesn't look right. Let me know if you'd like me to post screenshots of any particular ring tube lengths or diameters.

Some things that would be helpful to me would be some good info on the inside and outside diameters of different kinds of tube that I could use for the ring. I'd also like to get information about the weight of the different tubing options, so that I can plug it into the design and make sure I'm not getting out of the H and I motor range with the added weight. For that matter, I need to have an accurate Warlock OpenRocket file to start with --- I think this one is showing a little bit lower weight than I would expect.

If you've ever worked with the large tubing, or if you've ever built a rocket with a similar ring fin, I could use any advice you can offer.

Thanks!
 
Looks good, Thirsty.

Go for it.

Looks like you may need to slot the fins and the ring, the interlocking joints of which should then be filleted for additional strength. The fins usually bear the brunt of the landing impacts.
 
Just a couple thoughts-

1) Don't try to fly that on an H unless you're really certain it'll be enough motor. I think the LOC estimates of final build weight are often overly optimistic (or maybe I just overbuild).

2) This is a stubby rocket to begin with, and you're tweaking the design such that there will be even more mass at the aft end....you may very well find that you have to add nose weight in order to maintain even marginal stability (make sure you have at least 0.5 caliber) in which case see #1.

But yes absolutely, build it! :)

Edit: just read you post more carefully-- re: not wanting to get pushed into L2 motors, my gut says that's where this rocket would be happier. Maybe you could get away with a big I if you build light....but I think you should resign yourself now and commit to the next cert level ;)
 
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Also, 1010 rail is only 1" square so you should have no trouble with a 10" ringfin as long as it's just a rail launch and no other support. Have a look at Quikrete Quik-Tube in 10" diameter....*relatively* lightweight.
 
This looks awesome, and would be a very cool build. However, a full H in the stock warlock sims at only around 900, so this would probably be I motor only considering how LOC kits tend to weight a lot more than the package says (they say the magg is only 40 oz!). What are sims showing on I's with the extra weight and drag? If it can still fly to 1500-1800 on I's, it seems like this would work really well. Definitely will be a cool build!
 
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Looks good, Thirsty.

Go for it.

Looks like you may need to slot the fins and the ring, the interlocking joints of which should then be filleted for additional strength. The fins usually bear the brunt of the landing impacts.

Thanks, Kit. I agree that slotting the fins and ring for an interlocking joint would be the way to go.
 
Just a couple thoughts-

1) Don't try to fly that on an H unless you're really certain it'll be enough motor. I think the LOC estimates of final build weight are often overly optimistic (or maybe I just overbuild).

2) This is a stubby rocket to begin with, and you're tweaking the design such that there will be even more mass at the aft end....you may very well find that you have to add nose weight in order to maintain even marginal stability (make sure you have at least 0.5 caliber) in which case see #1.

But yes absolutely, build it! :)

Edit: just read you post more carefully-- re: not wanting to get pushed into L2 motors, my gut says that's where this rocket would be happier. Maybe you could get away with a big I if you build light....but I think you should resign yourself now and commit to the next cert level ;)

My rockets have typically ended up heavier than stock, and the other rocket I modified ended up MUCH heavier than expected. I got into a situation like what you described with so much weight aft that I had to weight the nose and then upgrade all the recovery gear --- a slippery slope.

As long as it would be flyable on a selection of L1 motors without going to L2, I would be happy. I could get still L2 down the road. The other rocket was still flyable on G motors --- it just was heavy enough that it required L1 to fly it at all, regardless of motor.
 
Also, 1010 rail is only 1" square so you should have no trouble with a 10" ringfin as long as it's just a rail launch and no other support. Have a look at Quikrete Quik-Tube in 10" diameter....*relatively* lightweight.

I would have to be really careful and get some good accurate measurements. The LOC tube is described as having an OD of 7.675. I think the rail guide itself would need at least .125" (x2 = .25). And then the 1" rail plus at least .125" extra clearance (1.125 x2 = 2.25). So 7.675 + .25 + 2.25 = 10.175. The inner diameter of the ring needs to be just a hair over 10". I've heard the various concrete forms are not precision sizes, so maybe there is something with the right inside diameter. Or maybe there is some other kind of tube I could use. I'd like to get the close to 10" I think, but it sure would suck to build it and not have it fit on the rail!
 
This looks awesome, and would be a very cool build. However, a full H in the stock warlock sims at only around 900, so this would probably be I motor only considering how LOC kits tend to weight a lot more than the package says (they say the magg is only 40 oz!). What are sims showing on I's with the extra weight and drag? If it can still fly to 1500-1800 on I's, it seems like this would work really well. Definitely will be a cool build!

Thanks, SC. I haven't done any real sims yet. Did you say you have a .rkt file for the Warlock that came with RockSim? I have downloaded two different files from internet searches, but I think there are inaccuracies in both of them. The first .rkt file had an issue with the fin shape being screwy. The second shows a weight of only 91oz for the Warlock before adding the ring fin --- I think that is too low.

As a starting point I need an accurate Warlock .rkt or .ork file for the stock kit, and a realistic estimate for the final build weight of a stock rocket. Then I'm going to need a decent estimate of the weight of the ring. Then I think I can work from there with calculating nose weight and getting the stability and final weight figured out for the sims. Of course, even then, the sims are not going to be 100% accurate in OR, because OR doesn't calculate drag for ring fins! I think I see why so many kit-bashers rely on the "mind sim" and "hope sim" methods!
 
I would have to be really careful and get some good accurate measurements. The LOC tube is described as having an OD of 7.675. I think the rail guide itself would need at least .125" (x2 = .25). And then the 1" rail plus at least .125" extra clearance (1.125 x2 = 2.25). So 7.675 + .25 + 2.25 = 10.175. The inner diameter of the ring needs to be just a hair over 10". I've heard the various concrete forms are not precision sizes, so maybe there is something with the right inside diameter. Or maybe there is some other kind of tube I could use. I'd like to get the close to 10" I think, but it sure would suck to build it and not have it fit on the rail!

Mmmm you're right, the ringfin ID will have to be larger than 10". Don't forget that the radial distance for the 1010 rail will be more than 1"....since it is 1" square and the corners need to fit within the arc. A 1" square can be inscribed within a circle of diameter 1.414". But since one face of the rail will abut the airframe you'll be adding a total radial distance of 1.207" to clear the outside corners. This is without any extra clearance added, so your numbers should sum up like:

7.675 (airframe OD) + 0.25 (rail button) + 2.4 (rail 1.2 x2) + 0.25 (slop) = 10.575 minimum ringfin ID
 
Thanks, SC. I haven't done any real sims yet. Did you say you have a .rkt file for the Warlock that came with RockSim? I have downloaded two different files from internet searches, but I think there are inaccuracies in both of them. The first .rkt file had an issue with the fin shape being screwy. The second shows a weight of only 91oz for the Warlock before adding the ring fin --- I think that is too low.

As a starting point I need an accurate Warlock .rkt or .ork file for the stock kit, and a realistic estimate for the final build weight of a stock rocket. Then I'm going to need a decent estimate of the weight of the ring. Then I think I can work from there with calculating nose weight and getting the stability and final weight figured out for the sims. Of course, even then, the sims are not going to be 100% accurate in OR, because OR doesn't calculate drag for ring fins! I think I see why so many kit-bashers rely on the "mind sim" and "hope sim" methods!

Mindsim is very reliable :fly:

Here's the rocksim file I have for the Warlock. It's modified a bit, no nose weight and with a tail cone for base drag, the sim says 106 oz.

View attachment PK-80 Warlock.RKT
 
Mmmm you're right, the ringfin ID will have to be larger than 10". Don't forget that the radial distance for the 1010 rail will be more than 1"....since it is 1" square and the corners need to fit within the arc. A 1" square can be inscribed within a circle of diameter 1.414". But since one face of the rail will abut the airframe you'll be adding a total radial distance of 1.207" to clear the outside corners. This is without any extra clearance added, so your numbers should sum up like:

7.675 (airframe OD) + 0.25 (rail button) + 2.4 (rail 1.2 x2) + 0.25 (slop) = 10.575 minimum ringfin ID

Thanks for pointing that out, and the math sounds about right. I might even go for just a bit extra slop and call it a 10.75" ID, which would probably be close to an 11" OD. I don't even have the rocket yet, so I've got some time to do some research and see if I can get a tube or other kind of material that will come close.
 
Mindsim is very reliable :fly:

Here's the rocksim file I have for the Warlock. It's modified a bit, no nose weight and with a tail cone for base drag, the sim says 106 oz.

Thanks! I'll see how this compares to what I have, but the weight sounds a bit more realistic.
 
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