EZI-65 Max Altitude Build

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neond7

neond7

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The goals for this EZI-65 build are simple - win a contest (work sponsored event) of who can launch the highest dual deploy 4" rocket using a CTI I242W motor.

With that goal, I selected the EZI-65 kit and will be making the following mods:

1. Addition of an Aeropack tail cone to reduce base drag.
2. Addition of a LOC Precision avionics bay.
3. Adding a 15" payload section (stock is 10").
4. Shortening main body tube ~4" to avoid adding length due to longer payload section.
5. Replaced blunt nose cone with 4:1 ogive cone from binder design.

Any suggestions are welcome!

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Last edited:
So far, I have stripped the glassine from the motor tube and added the Aeropack retainer.

This is my first time using a tail cone, my concern is getting the centering rings perfect so the cone can thread all the way in flush.

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Your goal should be to reduce weight as much as possible. The motor you're using is by no means a "shred risk" for this rocket, so you can build it lightweight and be successful. I'd do the following:

- Boat tail (you've done this, however there may be lighter ways to do it than an Aeropack...not sure.
- Build the rocket using Titebond wood glue or equivalent, using minimal fillets.
- No steel components anywhere such as allthread, eyebolts, quick links, etc...use knots.
- Affix your altimeter and battery horizontally to the bulkhead, no need for allthread and a traditional sled. A StratologgerCF or RRC2+ should fit on the bulkhead along with a 9V or a smaller LiPo.
- Cut the base off of your nosecone
- Single deployment with a small (24"-30" chute, or 36" x-chute)

All of the above tips and tricks should maximize altitude. Your #1 enemy is weight, so cut it down as much as possible. Hell, you may even want to keep the LOC shock cord attachment method, elastic cord, and use wadding!
 
A few quick sims from Thrustcurve suggests that if you can get the Cd down to 0.3, you should apogee ~ 5,600' for with the factory suggested mass of 35 oz. w/o motor on an AT I65.

The sims also suggest that a lower weight increases the apogee with the I65 down to at least 30 oz. and maybe lower.

YMMV.

Bob
 
Tonight I hopefully figured out the best way to align the rear centering ring and allow the tail cone to fit flush into the body tube. It's my first time using one.

First I pushed the dry fit MMT and rings into the body and used a thin screwdriver to nudge the rear ring flush against the bottom edge of the slot.

ImageUploadedByRocketry Forum1430789262.961750.jpg

I then carefully removed the tailcone and used JB Weld to add a rear fillet to bond the rear CR to the MMT.

ImageUploadedByRocketry Forum1430789286.132577.jpg

Once cured, I'll epoxy on the middle and front CR's, making sure to not get any where the fins go.

I only used JB Weld for this step because it was all I had on hand. I haven't put my new Aeropoxy structural into squeeze bottles yet, so once I do that I'll use Aeropoxy for the rest of the build.
 
I have no experience here but does everyone have to use the same motor (-W)? Wouldn't you also attain higher flights with a lower thrust, longer burn motor (-J) to reduce drag?

Where does one work that sponsors something as fun as this & what's the prize? :)
 
I saw a long time ago under "you know you're a rocket nut if..." which says

Fly a EZI-65 on a J350 and watch it rain confetti.
 
grapetang said:
I have no experience here but does everyone have to use the same motor (-W)? Wouldn't you also attain higher flights with a lower thrust, longer burn motor (-J) to reduce drag?

Where does one work that sponsors something as fun as this & what's the prize? :)
Click to expand...

Yes, we all have to use the same CTI-I242w motor. It's the highest Newton level 1 motor (to the best of my knowledge). Not everyone is involved has a level 2 cert.

I work at Kennedy Space Center, although the contest is sponsored by our corporate office in Lanham, MD. It's basically "KSC vs Lanham".

This is actually the second rocket I'm building for the contest. Earlier in the year I assembled a Binder Design Excel, which suffered damage on its maiden flight two months ago when the motor malfunctioned and the motor casing shot up into the rocket and broke the rear of the avionics bay.

ImageUploadedByRocketry Forum1430820255.316325.jpg
Both motors with that manufacture day failed the exact same way - CTI warrantied them both.
Anyway, the damage is repairable and I should be reflying that one this Saturday and then the EZI-65 next month. We found out the corporate office guys were building several rockets, so that is why I'm building this one and trying very hard to keep it light as possible. Hope the tailcone reduces enough bases drag to make up for t the extra weight.
 
Buckeye said:
Sure about this? HPR rockets + motors usually have an attainable optimum mass for max altitude. Runs some sims to check.
Click to expand...

I understand optimal mass. My statement was based on the fact that he will likely be adding a lot of weight through the usage of epoxy, adding an altimeter bay, and adding another shock cord and chute protector for dual deployment. Also adding paint and decals will increase weight and drag.

Agreed that simulations should be run. In this case, the motor is by no means extreme for this size of airframe and therefore it's likely that lightweight is the way to go.
 
patelldp said:
I understand optimal mass. My statement was based on the fact that he will likely be adding a lot of weight through the usage of epoxy, adding an altimeter bay, and adding another shock cord and chute protector for dual deployment. Also adding paint and decals will increase weight and drag.

Agreed that simulations should be run. In this case, the motor is by no means extreme for this size of airframe and therefore it's likely that lightweight is the way to go.
Click to expand...

I have been running simms in OpenRocket. The avbay alone is a hefty weight addition, so I'm definitely building it light. Still debating if the tailcone was a good idea.
A shred is highly unlikely, I have a LOC Fantom which is very similar (thin fins) that I feed J350's and I435's all the time. I think LOC must have released a version 2 of the EZI-65, which is beefed up more than the original ones I've seen build threads for. It now has three centering rings and a longer motor tube, so the fin roots are nicely sandwiched.

OpenRocket showed a decrease in max altitude when i increased the length of the payload bay (necessary to fit the parachute). Shortening the body tube 4" fixes that issue.

I'm going light on the epoxy - you don't need to apply much when you use Aeropoxy. :)
 
Naram 56 I watched two Australian guys fly the EZI-65 on a K 550 W, I don't remember the altitude but I do know it had no problem with stock build!
 
I'm building an EZI-65 for my L2 flight (one of these days.) The LOC Imprecision centering rings didn't fit the airframe so I got new ones from PML. Other than that it seems like a nice kit in that it's easy to build and easy to customize. (Added an Aeropack retainer and PML 3.9" to 75mm tailcone; I wanted the tailcone shoulder hard against the aft centering ring, which placed the ring about 1/8" to 1/4" off the original position, which meant I had to extend the fin slots, but it all went quite easily.) My avatar is the paint job I'm going with. Yeah, really.
 
I'm following people's suggestions and using TightBond II wood glue in places to save weight. I'll still probably use epoxy for the external fillets, though.
It went on pretty thin.... I'm so used to working with thickened epoxy that this felt totally weird applying.
Tomorrow I'll get the MMT epoxied into the body tube. I'll probably use Aeropoxy structural for that, I'm afraid the TightBond will "grab" before it gets in the right spot.

ImageUploadedByRocketry Forum1431876014.980287.jpgImageUploadedByRocketry Forum1431876028.066534.jpg
 
My last 4" build used TBII for everything except the fillets. I was a little concerned about the grabbing too but it wasn't an issue. I thing it comes into play more with couplers with their much increased surface area. I will say this, my wood glue build is not only my lightest builds it also the strongest. From here on out, wood glue for the build and epoxy for laminating and fillets.
 
Sounds fun! No 5G motors? I540 crushes other I motors but probably burns too fast for max altitude. There is a nice long burn white, or even the 5G skidmark could be a fun twist although you are carrying dead weight for those sparks.

I would probably skip the Aeropack, use tape, and attempt to deploy from the nose.
 
watermelonman said:
Sounds fun! No 5G motors? I540 crushes other I motors but probably burns too fast for max altitude. There is a nice long burn white, or even the 5G skidmark could be a fun twist although you are carrying dead weight for those sparks.

I would probably skip the Aeropack, use tape, and attempt to deploy from the nose.
Click to expand...

The I216 would be perfect, it's 634 ns (same as the I540), but with a 3 second burn time and both are almost 100 ns more than the I242. The I125 you mentioned would also be great although it's only 567 ns. Ironically the 5G skid is actually less impulse than the 4G white.

I'll second what everyone mentioned about titebond.

Neond7, would it be possible to motor deploy and remove the payload section completely? That would probably get you a bit more altitude.

Sounds like a very fun contest!
 
neond7 said:
Yes, we all have to use the same CTI-I242w motor. It's the highest Newton level 1 motor (to the best of my knowledge). Not everyone is involved has a level 2 cert.

I work at Kennedy Space Center, although the contest is sponsored by our corporate office in Lanham, MD. It's basically "KSC vs Lanham".

This is actually the second rocket I'm building for the contest. Earlier in the year I assembled a Binder Design Excel, which suffered damage on its maiden flight two months ago when the motor malfunctioned and the motor casing shot up into the rocket and broke the rear of the avionics bay.

View attachment 262493
Both motors with that manufacture day failed the exact same way - CTI warrantied them both.
Anyway, the damage is repairable and I should be reflying that one this Saturday and then the EZI-65 next month. We found out the corporate office guys were building several rockets, so that is why I'm building this one and trying very hard to keep it light as possible. Hope the tailcone reduces enough bases drag to make up for t the extra weight.
Click to expand...

Why hello there neighbor. I work out at KSC as well. Are you a member of SRA or where do you usually launch?
 
dingle said:
Why hello there neighbor. I work out at KSC as well. Are you a member of SRA or where do you usually launch?
Click to expand...

Hey neighbor! Glad to see another KSC employee in the hobby - I'm surprised (and saddened) at how few there are.

I flew at SRA once for my L1 flight. Call me a prim a dona, but I have no idea how anyone can fly on such an overgrown and heavily wooded field..... I almost gave up on high power after I spent a long time in brush up to my head trying to find my rocket.

Luckily I found two great fields, now I mostly fly up in Bunnell with the NEFAR group, or at Tampa (Plant City) with the TRA group. NEFAR flies at the Clegg Sod farm. Imagine flying on acres of freshly mowed sod!! Its that nice and definitely worth the drive. :)
 
SCrocketfan said:
The I216 would be perfect, it's 634 ns (same as the I540), but with a 3 second burn time and both are almost 100 ns more than the I242. The I125 you mentioned would also be great although it's only 567 ns. Ironically the 5G skid is actually less impulse than the 4G white.

I'll second what everyone mentioned about titebond.

Neond7, would it be possible to motor deploy and remove the payload section completely? That would probably get you a bit more altitude.

Sounds like a very fun contest!
Click to expand...

We are having a "blast" down here with this contest! Our team of three has built three very nice rockets.

We have to use dual deploy as part of the contest, so I can't remove the payload bay. The dual deploy requirement was to help several members get some experience and work towards their L2 certs. We also are restricted to using the I242 motor.

This will probably end up being a yearly contest with different rules every time, so I'll keep suggestions in mind when we write the rules for the next one.
 
SCrocketfan said:
The I216 would be perfect, it's 634 ns (same as the I540), but with a 3 second burn time and both are almost 100 ns more than the I242. The I125 you mentioned would also be great although it's only 567 ns. Ironically the 5G skid is actually less impulse than the 4G white.
Click to expand...

Hah definitely! I literally forgot that motor exists because it is not listed by Wildman, which I use as my authoritative motor list, because the Cesaroni and Aerotech pages stink. The skidmark obviously would not be for a world record but rather to inject some fun, and probably would not be all that much of a penalty.
 
neond7 said:
Hey neighbor! Glad to see another KSC employee in the hobby - I'm surprised (and saddened) at how few there are.

I flew at SRA once for my L1 flight. Call me a prim a dona, but I have no idea how anyone can fly on such an overgrown and heavily wooded field..... I almost gave up on high power after I spent a long time in brush up to my head trying to find my rocket.

Luckily I found two great fields, now I mostly fly up in Bunnell with the NEFAR group, or at Tampa (Plant City) with the TRA group. NEFAR flies at the Clegg Sod farm. Imagine flying on acres of freshly mowed sod!! Its that nice and definitely worth the drive. :)
Click to expand...

One word. GPS. :D

Google says the sod farm is only about 13 more minutes of a drive from my house than the SRA site is. I will see if I can make it out there sometime I'm sure my son would like it much more than SRA as he's only 6 and just a little guy. That tall grass doesn't agree with him at all. lol
 
jqavins said:
Umm, am I the only one who sees the irony?
Click to expand...

Not like I am trying to hide it. The Cesaroni and Aerotech motor list pages stink. Wildman gives nice big buttons, organized sensibly, and easy to use mobile or desktop.

The Loki pages are great. I have no idea why the big companies cannot have a web page as usable and informative as a one man operation. I would love to support him, but, California.
 
dingle said:
One word. GPS. :D

Google says the sod farm is only about 13 more minutes of a drive from my house than the SRA site is. I will see if I can make it out there sometime I'm sure my son would like it much more than SRA as he's only 6 and just a little guy. That tall grass doesn't agree with him at all. lol
Click to expand...

That would be great, hope to see you out there next month! There is a map to the site at www.nefar.net, if you use a Garmin it puts you a little short of the actual launch field and you won't see the line of tents until you go to the stop sign and take a left.
 
Last night I got the MMT/centering ring assembly glued into the body tube. In the interest of saving weight I again used Tight Bond II.

Luckily I got it into position really fast, as the Tight bond "grabbed" quickly. If I had needed to slide it forward a hair more, it would have been really difficult or impossible.

I tried to add a fillet to the front centering ring, but as you can see in the picture, the glue was pretty runny and just sort of leveled out. Either way, it's solidly glued in and not going anywhere.

Next up, I'll be using Aeropoxy structural epoxy to bond in the fins. I'll then add small fillets with West Systems epoxy thickened with colloidal silica and high density filler.

ImageUploadedByRocketry Forum1432214202.177740.jpgImageUploadedByRocketry Forum1432214227.372998.jpg
 
jqavins said:
What's that in the background? I like what I see with the concave trailing edged fins.
Click to expand...

That rocket in the back ground is a 29mm Binder Design Bat kit. It can fly on "G" motors, something I will fly at the local park until I get my new G-Force build to replace the one that crashed.

Eventually when I whittle down my build pile, I'll get the 38mm dual deploy version. My friend has one that I helped her assemble. It's a great flying kit and hopefully she can use it to get her L2 with it.
 

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