LOC 4" Iris build for L2 Certification Attempt

[T.Weeks]

Thanks for the SIM files!..

This thread will pick up where this one left off, since I got the advice on kit choice I asked for (and then some) and the kit arrived two days ago.
...

I ordered a J381 from Chris Rocket Supplies for pickup on site at LDRS. Yes, I plan to launch this puppy just three wee

No wa! I'm about to fly mine at 2024 LDRS.. and needed to sim it for a K 3 grain research motor..

I did an early test flight, and those big dumbo-ear fins were just too sensitive to impacts.. So I decided to do a tip to tip reinforced carbon fiber:


I just started on the paint job this week.. so it's not completely done yet, but I at least got the big fins painted red (all but one.. to show off the CF).. and the metal--finished upper. This is going to be super sharp once it's done!


Thanks for the corrected SIM!

More pics of my build here...


T.Weeks
nrvr.org

 

[NTP2]

thought I could have finished tonight, ahead of schedule, had I not taken last Saturday off.

Ahhh well, it makes a good climax!

Thanks for the SIM files!..



No wa! I'm about to fly mine at 2024 LDRS.. and needed to sim it for a K 3 grain research motor..

I did an early test flight, and those big dumbo-ear fins were just too sensitive to impacts.. So I decided to do a tip to tip reinforced carbon fiber:
View attachment 649038

I just started on the paint job this week.. so it's not completely done yet, but I at least got the big fins painted red (all but one.. to show off the CF).. and the metal--finished upper. This is going to be super sharp once it's done!
View attachment 649043

Thanks for the corrected SIM!

More pics of my build here...


T.Weeks
nrvr.org

Thomas!! Good to see what you’re bringing! Looks sick! What day you planning on?

 

[T.Weeks]

Ahhh well, it makes a good climax!

Thomas!! Good to see what you’re bringing! Looks sick! What day you planning on?

I drive in Thur night.. so I'll be Flying Fri-Sat.. maybe hang out Sun morning and then head back to Virginia.. You going to be there?

I'm bringing the two L2s above.. one of which is flying on a home made APCP three gain 54mm K. Here's some photos of me and my club at the APCP mixing party.

For LDRS this year, I was going to bring my 6" L3 Black Brant.. but it's still naked (has been since 2017!).. and needs some fin strengthening before I fly it high and fast again..

If you're going.. I'm staying at the Super 8 by Wyndham Canandaigua..
If you're there.. let's connect..

T.Weeks

 

[NTP2]

I drive in Thur night.. so I'll be Flying Fri-Sat.. maybe hang out Sun morning and then head back to Virginia.. You going to be there?

I'm bringing the two L2s above.. one of which is flying on a home made APCP three gain 54mm K. Here's some photos of me and my club at the APCP mixing party.

For LDRS this year, I was going to bring my 6" L3 Black Brant.. but it's still naked (has been since 2017!).. and needs some fin strengthening before I fly it high and fast again..

If you're going.. I'm staying at the Super 8 by Wyndham Canandaigua..
If you're there.. let's connect..

T.Weeks

I’ll be there Saturday, I’ll try and find you!

 

[jqavins]

Well, this is why I shouldn't have taken Saturday off.

I started be marking and masking boundaries for the fin fillers. That went fine, but I didn't take a picture.

Then I started to mix up some epoxy. The scale switched off between the two components, but that doesn't matter since I was about to tare it anyway, right? So I started squeezing out the second component and it shut off part way through. Well, let's see, I need 10 g, I think I was at about 3.5, so I need 6.5 more. When it turned off again, I was watching this rime, and I needed about 2 g more. I got it all poured and mixed, then added some chopped glass fiber. Turns out, it's got more of a flakey consistency than I expected, which made for a sticky, flakey mess in the mixing cup. I should have stopped. But what I did was make the ugliest two fillets of my life, maybe the worst I've ever seen. I just checked on it: the epoxy is well hardened, and I can't pull the tape, so I'll be cutting or grinding some of the epoxy back enough to get that off. I guess I was supposed to pull the tape before the epoxy fully hardened, huh?

I'll switch to wood meal for the other fillets. Before mixing, I'd better put fresh batteries in the scale. It takes AAAs; I was afraid it would need button cells, But I should have AAAs. Nope, just one.

This is why I shouldn't have taken Saturday off.

The weather look really bad tomorrow, and I'd have to get up extra early because of my wife's schedule, so I think I'll stay home and try to fix this mess.

(I did work on three other rockets instead.)

 

[-Slick-Ice]

Part of the reason I have been using totalboat thixo a lot. It is over-priced for epoxy but the curing time has been perfect and I don't need to inhale glass beads.

 

[NTP2]

Well, this is why I shouldn't have taken Saturday off.

I started be marking and masking boundaries for the fin fillers. That went fine, but I didn't take a picture.

Then I started to mix up some epoxy. The scale switched off between the two components, but that doesn't matter since I was about to tare it anyway, right? So I started squeezing out the second component and it shut off part way through. Well, let's see, I need 10 g, I think I was at about 3.5, so I need 6.5 more. When it turned off again, I was watching this rime, and I needed about 2 g more. I got it all poured and mixed, then added some chopped glass fiber. Turns out, it's got more of a flakey consistency than I expected, which made for a sticky, flakey mess in the mixing cup. I should have stopped. But what I did was make the ugliest two fillets of my life, maybe the worst I've ever seen. I just checked on it: the epoxy is well hardened, and I can't pull the tape, so I'll be cutting or grinding some of the epoxy back enough to get that off. I guess I was supposed to pull the tape before the epoxy fully hardened, huh?

I'll switch to wood meal for the other fillets. Before mixing, I'd better put fresh batteries in the scale. It takes AAAs; I was afraid it would need button cells, But I should have AAAs. Nope, just one.

This is why I shouldn't have taken Saturday off.

The weather look really bad tomorrow, and I'd have to get up extra early because of my wife's schedule, so I think I'll stay home and try to fix this mess.

(I did work on three other rockets instead.)

i did that on my cyclotron, I just left the tape entombed in it and you would never know since I panted it.

 

[4regt4]

I concur. I'm putting mine up on a K550 this weekend. Rocksim says 11,000'.

View attachment 646548

Re-awakening this...

I'm thinking about the 4" Iris for L2 cert. I'm using LOC's .rkt file in OpenRocket with the fins adjusted as mentioned above. It shows 4892ft with a K550! I wonder what is wrong. My resulting .ork file shows a weight of 68.4oz w/o motor. The only override comes from the original file, and that's 10oz for the nose cone. I'm wondering if there is something haywire in OR's motor file for the K550W.

Hans.

 

[kjhambrick]

I don't see anything wrong with the AT RMS 54/1706 K550W in OpenRocket but 4900 ft seems like it might be a tad low for a 68 oz, 4-inch IRIS.

My ex-IRIS weighed 7.5 lb / 120 oz dry and according to my AltAcc, I would get 6000 -to- 6800 ft on a K550 every time, depending on the site altitude and temperature and the barometric pressure.

Maybe post your .ork ?

-- kjh

p.s. ex-IRIS because I broke a fin and I've not flown it since 1998

 

[-Slick-Ice]

I would believe 6000 ft. Mine is 111 oz no motor.

 

[4regt4]

I don't see anything wrong with the AT RMS 54/1706 K550W in OpenRocket but 4900 ft seems like it might be a tad low for a 68 oz, 4-inch IRIS.

My ex-IRIS weighed 7.5 lb / 120 oz dry and according to my AltAcc, I would get 6000 -to- 6800 ft on a K550 every time, depending on the site altitude and temperature and the barometric pressure.

Maybe post your .ork ?

-- kjh

p.s. ex-IRIS because I broke a fin and I've not flown it since 1998

As I don't (as yet) have a kit to see if the .ork is accurate, all I'm doing is using the .rtk file given above, and correcting the fins as previously mentioned. Also, I change the paint surface, as the .rkt files seem to default to 2um when imported to OR.

But here's what I'm using.

Hans.

 

[4regt4]

I'll add that the "information" tab on the K550W in OR shows 2 different thrust curves. I can only guess that they are using the black one, as it shows individual data points and the red one does not.

Hans,

 

[kjhambrick]

Hmmm ...

All I see is that the components are unfinished which affects drag.

Also, I usually unclick "Use Std Atmosphere" and enter a reasonable temperature and pressure for the launch site

Maybe 1958 grams / 69 oz is too light ?

What happens to the Altitude if you raise the dry mass by adding a "Mass Component" at the Dry CG ?

HTH.

-- kjh

 

[kjhambrick]

Eek !

Back in Post #12, I said:

Rocket Envy !

My old 4-inch Iris only got about 9,000 ft on a K550.

But it was a BEAUTIFUL flight with that majestic pillar of white smoke and long, loud flame

-- kjh

I went and looked at my old AltAcc data before I wrote Post #38 and the four flights of my 120 oz IRIS on K550s were all in the 6,000 to 6,800 ft range.

Sorry, too late to edit post #12 to fix my bad altitude info !

-- kjh( and now I am really envious of that 11,000 foot flight )

 

[4regt4]

Hmmm ...

All I see is that the components are unfinished which affects drag.

Also, I usually unclick "Use Std Atmosphere" and enter a reasonable temperature and pressure for the launch site

Maybe 1958 grams / 69 oz is too light ?

What happens to the Altitude if you raise the dry mass by adding a "Mass Component" at the Dry CG ?

HTH.

-- kjh

Yeah, I switched the component's surfaces to Unfinished, as on many of my other builds that was needed to get the Cd so that the sims agreed with reality after doing several flights. Just being lazy, as the other way to do it is to go into Overrides and manually enter Cd guesstimates until the sims look good.

I'll tinker with mass, but it will be flying in the dark, as I don't have the actual rocket to see what is a realistic as-built mass.

Hans.

 

[-Slick-Ice]

I normally just override the MASS and CG for all of my rockets. I didn't for this one but it looks close enough.

It also did get heavier because I replaced the LOC parachute with a recon.

Disclaimer - At a minimum please validate the rail length, altitude, wind, CG, mass

 

[kjhambrick]

Thanks @-Slick-Ice !

Your 4-IRIS-DUAL-N.ork file gave very reasonable sim results -- right in the ballpark for my 120 oz IRIS with an AltAcc.

That is a keeper for me

Stolen.

-- kjh( what ??? no L1090W sim ??? )

 

[-Slick-Ice]

The J415W is already risky enough in this field.

 

[jqavins]

4900 ft seems like it might be a tad low for a 68 oz, 4-inch IRIS.

My ex-IRIS weighed 7.5 lb / 120 oz dry and according to my AltAcc, I would get 6000 -to- 6800 ft on a K550...

I guess the iris has dilated since then.

 

[kjhambrick]

I guess the iris has dilated since then.

Well mine had a lot of dark paint on it.

Especially after 3 -or- 4 flights -- the silver was pretty ugly by the end

-- kjh

 

[jqavins]

Incidentally, even though LDRS was a disappointment, and not only because of failing to get this done, it's still sitting prominently on my rocket desk, and I will finish it and get that cert. Maybe not until Spring, but darn it, I will.

 

[NTP2]

Incidentally, even though LDRS was a disappointment, and not only because of failing to get this done, it's still sitting prominently on my rocket desk, and I will finish it and get that cert. Maybe not until Spring, but darn it, I will.

I’m in the same boat. I at least got to test mine.

 

[FlyBy01]

Come to Virginia; our season starts soon.

 

[NTP2]

Come to Virginia; our season starts soon.

I did.

 

[FlyBy01]

I did.

The season starts this October (2024) and should be posted soon. https://battlepark.org/ The launch site is approximately 3 hours from you and if you need more information please reach out to our Prefect through the website or feel free to ask me any questions. Sounds like you are very close!