Full scale Iris

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SMS Engineering
Posts: 12
Joined: Wed Nov 18, 2015 11:51 am

Full scale Iris

Postby SMS Engineering » Thu Dec 31, 2015 8:50 pm

So I have been slowing down in the hobby for a few years now , and I haven't built a rocket of any real size. It is time to fix this . This will be a slow build , several months I'm guessing .

I am resurrecting and finishing the CTRA club project from 2005 . We wanted to build a full scale two stage Iris . The booster was going to be boosting on 7 38 mm DPS J2000 motors , staging to a 20k 4.5 inch N1000 AN motor .

My main goal on this rocket is to build it as light as possible , with a full up weight of both stages on the pad , of less then 50 lbs . The sustainer will be the bulk of the weight at about 35/38 pounds . It will house a center 75mm and 4 outboard 38mm mounts . The booster will have 7 38mm mounts . Both stages are being built as main deploy , but the upper will have a AARD mounting setup installed .

The fins have been started , and weigh in at just over 1.3 pounds each. They are 1 inch blue foam hot wired and sanded to scale , with 4 layers of 5 oz sglass . I need to trim the fin tabs to its final length . They where made long on purpose to leave motor mount options open . I'm hoping to get each fin to right around 1.1 pounds each . The main construction of both stages will be 2 part 2lb density foam sprayed over a stuffer tube inner skeleton . The fins will be removable for transport and storage .

The rocket will be cut to shape with a hot wire cutter . The centering rings will act as a form for the wire to run on . Once cut , the foam will receive a layer of glass sock . The upper nose cone will get reinforced with two layers of glass to aid in landing damage .

The rocket is going to be built to break down into 3 five foot sections and one 4.75 foot section . The lower two 5 foot sections will lock together for flight via the stuffer tube and four 1/8th turn lock pins . Once locked down , a pin will be inserted thru the rocket to keep it from trying to turn . The upper 3 feet of airframe tube and the first 2 feet of the nosecone will be one peice . The last 56 inches of the nosecone will be the last section. The upper two sections will lock together in the same manor as the lower airframe .

First flight will be the sustainer only this spring on a K to about 1500 feet . For the big two stage flight I want to cluster 7 CTI I345 WTs to the 75mm 5 grain L395 mellow and 4 CTI J150 mellows .


Eric

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patelldp
Posts: 160
Joined: Thu Nov 05, 2015 5:07 pm
Location: New York

Re: Full scale Iris

Postby patelldp » Thu Dec 31, 2015 10:11 pm

Eric,

Thanks so much for posting this here! I hope you find the picture uploading easy to use.

I seem to recall you're in Elmira? I grew up in Painted Post...small world!
Dan Patell
TRA 10904 L3

SMS Engineering
Posts: 12
Joined: Wed Nov 18, 2015 11:51 am

Re: Full scale Iris

Postby SMS Engineering » Fri Jan 01, 2016 12:15 pm

I seem to recall you're in Elmira? I grew up in Painted Post...small world!

Nope , still living in VT .

Here are a couple of fin pics .

IMG_20160101_121054.jpg
12 inch ruler shown for scale

IMG_20160101_121042.jpg
Top of fin showing shape

SMS Engineering
Posts: 12
Joined: Wed Nov 18, 2015 11:51 am

Re: Full scale Iris

Postby SMS Engineering » Fri Jan 01, 2016 12:16 pm

Forgot to mention the leading and trailing edges are oak .

DBMcCann
Posts: 103
Joined: Thu Nov 05, 2015 9:22 pm

Re: Full scale Iris

Postby DBMcCann » Fri Jan 01, 2016 1:16 pm

This looks like an impressive project! Very interested to see this one...

Alexander
Posts: 46
Joined: Tue Nov 24, 2015 9:45 am

Re: Full scale Iris

Postby Alexander » Fri Jan 01, 2016 3:14 pm

I'll tag along, this is going to be awesome.
Alexander Solis

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patelldp
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Location: New York

Re: Full scale Iris

Postby patelldp » Sat Jan 02, 2016 8:30 pm

Did they purchase all of the motor cases, etc?

I know all the old CTRA crew...this has Stackpole written all over it!
Dan Patell
TRA 10904 L3

SMS Engineering
Posts: 12
Joined: Wed Nov 18, 2015 11:51 am

Re: Full scale Iris

Postby SMS Engineering » Sun Jan 03, 2016 1:05 am

patelldp wrote:Did they purchase all of the motor cases, etc?

No . midway thru I suggested a 7 K1100 cluster instead and we started redesigning the whole rocket .

I know all the old CTRA crew...this has Stackpole written all over it!


Guilty as charged . I will be contacting you in the spring . I will be needing 4 x 38/1200 and a 54/2550 .

After doing a bunch of math and design on this rocket , I'm looking at a .82 lbs per foot for the main 15 feet of airframe . The upper nose section should weigh in around 5 pounds . It will have extra reinforcement to keep the nose from shearing on ground impact . I'm saying another 5 pounds for the fins . 8 pounds for the inner structure , and maybe 5 pounds for recover gear .

The booster motor mount will consist of 6 x 38mm and 1 54 center . The sustainer will have a center 75 , 4 x 38s and 4 29s . The 29s will act as staging sockets to accept the booster thrust plate.

I will be using 8 full length stringer to keep the rocket stiff and to keep it from buckling under load.
Last edited by SMS Engineering on Sun Jan 03, 2016 1:07 am, edited 1 time in total.

SMS Engineering
Posts: 12
Joined: Wed Nov 18, 2015 11:51 am

Re: Full scale Iris

Postby SMS Engineering » Sun Jan 03, 2016 1:06 am

patelldp wrote:Did they purchase all of the motor cases, etc?

I know all the old CTRA crew...this has Stackpole written all over it!


Only the N motor . Wayne had it last I new .
Guilty as charged . I will be contacting you in the spring . I will be needing 4 x 38/1200 and a 54/2550 .

After doing a bunch of math and design on this rocket , I'm looking at a .82 lbs per foot for the main 15 feet of airframe . The upper nose section should weigh in around 5 pounds . It will have extra reinforcement to keep the nose from shearing on ground impact . I'm saying another 5 pounds for the fins . 8 pounds for the inner structure , and maybe 5 pounds for recover gear .

The booster motor mount will consist of 6 x 38mm and 1 54 center . The sustainer will have a center 75 , 4 x 38s and 4 29s . The 29s will act as staging sockets to accept the booster thrust plate.

I will be using 8 full length stringer to keep the rocket stiff and to keep it from buckling under load.


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