Build Thread - 4" Patriot (1/4 scale)

eeymontt · May 1, 2014

Yesterday I began prepping the build for my 4 Madcow Patriot. All the parts arrived today and nothing appears to be broken. I was thinking of making one small change to the instructions via the placement of the aft CR on the MMT, sliding it backward 1/8 inch to allow space for my 3829 mm motor adapter, having to account for the stability later. I expect to have to add a lot of ballast to the nosecone. For price reasons I decided to go with a post-build retention system.

Its going to be flown with a CTI H135 or something of the like based on the rockets dimensions and estimated weight. I dry fitted the parts together to get a better idea of the rockets overall size. The nosecone is stubby, and the fins are particularly small. Its spiffy, just like the real thing. I'll post an OR file as soon as I can for those interested.

And for those of you who dont know me, Im friends with TRF user eggplant, so Im from southern Maine. Ive had a passion for model rocketry for several years, co-building projects primarily. Im part of the MSSM rocketry club and this is my first HPR solo build.

Any suggestions on how I can improve this build? Much appreciated.

Rocket-Top · May 1, 2014

I just built the same rocket about two months ago - great kit! I ran some simulations on RockSim and decided right away to make it dual-deploy, because of the altitude it will reach with "J" motors. Plus, the extra weight of the AV bay toward the nosecone would help with the CG, too. As such, the CG was good, so I didn't have to add any weight in the nosecone.

I don't know how many other builders do this, but I smeared a coating of epoxy on the inside of the 4" body tubes for extra stiffness and strength, after the major components of the kit were in place.

You can watch the ground-level launch video on my YouTube channel here: https://youtu.be/29L9TvBsIDo. On the channel, as well, is the video of the on-board camera footage of the same flight. For its maiden flight I flew it on a CTI Pro38 J400SS to 3,325'. Top speed was 736mph.

Enjoy the build!

-Wendell

Rex R · May 1, 2014

are you building this as a 'cert' bird? I would suggest something more like an AT H242.
Rex

Exactimator · May 1, 2014

eeymontt said:
Yesterday I began prepping the build for my 4” Madcow Patriot. All the parts arrived today and nothing appears to be broken. I was thinking of making one small change to the instructions via the placement of the aft CR on the MMT, sliding it backward 1/8 inch to allow space for my 38–29 mm motor adapter, having to account for the stability later. I expect to have to add a lot of ballast to the nosecone. For price reasons I decided to go with a post-build retention system.

It’s going to be flown with a CTI H135 or something of the like based on the rocket’s dimensions and estimated weight. I dry fitted the parts together to get a better idea of the rocket’s overall size. The nosecone is stubby, and the fins are particularly small. It’s spiffy, just like the real thing. I'll post an OR file as soon as I can for those interested.

And for those of you who don’t know me, I’m friends with TRF user eggplant, so I’m from southern Maine. I’ve had a passion for model rocketry for several years, co-building projects primarily. I’m part of the MSSM rocketry club and this is my first HPR solo build.

Any suggestions on how I can improve this build? Much appreciated.

View attachment 170727 View attachment 170728

Nice! I got my L1 on that rocket.

I don't have any suggestions on how to improve the build. I built mine stock with added weight in the nose cone. I launched it many times on a CES H123 Skidmark. Never flew an altimeter, but it got up to about 1,300 feet or so on the H123.

Since the fins are small it's an excellent rocket for windy days. Very little weather cocking. Instead, it would wag its tail (cone) a bit and side slip with the nose pointing straight up.

The only thing I didn't like was the payload bay was a bit too small for dual deploy. I could have cut away the bottom of the nose cone and used the extra space, but decided to fly it single deploy only.

ETA: Rocket-top, how were you able to get all the main laundry in the payload?

eeymontt · May 1, 2014

Rocket-Top said:
I don't know how many other builders do this, but I smeared a coating of epoxy on the inside of the 4" body tubes for extra stiffness and strength, after the major components of the kit were in place.

Thank you for the insight. Considering the the length of the airframe of the rocket, I had been wondering how I could reinforce the sides. I will not be having a DD on the launch... this time.

Yes, I am planning on using the Patriot for my L1-cert. I am sadly limited to Cesaroni motors due to the vendor that will be available at the launch. I'll simulate the flight on the motor nonetheless.

Rex R · May 1, 2014

you could epoxy on the insides of the tubes...keep in mind that will add weight where you want it least. with nose weight mine weighs in at approx. 4.5 pounds, you'll want a fair amount of thrust to get it off the pad in good shape. since you need to know where the center of pressure is, I would recommend Open Rocket design software. also suggest a good size chute...48" would work nice.
Rex

Rocket-Top · May 1, 2014

Exactimator said:
Nice! I got my L1 on that rocket.

ETA: Rocket-top, how were you able to get all the main laundry in the payload?

Yes, the payload bay is rather small for holding the main chute, so I changed things up a bit and used the payload bay for the drogue, an 80" streamer. Then I had plenty of room for the 50" chute in the main body tube. Hey, I figure that I'm (we're) still learning, so I'm willing to try new things - at least new to me. It worked perfectly. On a side note, I have a Madcow removable 4" AV bay that I'm able to use for DD on this rocket, as well as other 4" diameter rockets - most recently, my Madcow Frenzy.

Rocket-Top · May 1, 2014

It you wanted to, instead of using epoxy to permanently fasten the coupler tube in place, you could temporarily fasten it in place with removable fasteners so that you could always remove the bay later to be able to insert the AV bay into the tubes for DD. That way, the rocket will be more versatile and can fly single- or dual-deploy. L1, then on to L2 w/DD. Just a thought.

Also, be cautious with the CTI Pro38 reloads (I learned this the hard way). From my understanding, they were the first reloads that CTI developed, and only have 1.3 grams of black powder in them for the ejection charge. For comparison, the Pro29s have 1.2 and the Pro54s have 2.0 grams, so not much more than the 29mm reloads. It's probably best to talk with another one or two of your club members to get their recommendations for the charge on the 38mm. You certainly don't want to put the time and energy into building a beautiful rocket only to find out the that ejection charge wasn't enough to blow out your chute! I use Cesaroni exclusively, however, except for smaller Estes-type rockets. They ARE great motors, and a great company!

eeymontt · May 1, 2014

Rocket-Top said:
It you wanted to, instead of using epoxy to permanently fasten the coupler tube in place, you could temporarily fasten it in place with removable fasteners so that you could always remove the bay later to be able to insert the AV bay into the tubes for DD. That way, the rocket will be more versatile and can fly single- or dual-deploy. L1, then on to L2 w/DD. Just a thought.

That's an idea. I was thinking of attaching a second eyehook facing into the coupler tube as an attachment point for a thread coming from the nosecone. Instead, I could make the whole setup modular for this flight and later repurpose the vital area within that section of the body tube for perhaps DD use.

T-Rex · May 1, 2014

I'll add my 2cents as well.... I'm bulding mine with later DD in mind. I plan to glue the coupler to the payload bay. Since weight has to be added anyway, I extended the payload bay by removing the base of the nosecone. I cut a 1 inch switch band from the lower tube to keep the payload tube length intact.
When flying SD, it will break in the middle, the nosecone held in place with removable rivets.
When flying DD, pull the rivets and friction fit or shear pin the nose.
It is untested, but works in my mind. Food for thought........

Enjoy!

Kehoes23 · May 1, 2014

eeymontt · May 1, 2014

Scuffed the glassine motor mount tube and marked, then taped, the region for the forward CR. After both sides of the internal fillets were epoxied, I glued in the eyehook. I also added a curved block of wood which hangs from the CR to be used as support. I will later drill one of the rail buttons into this block. I am under the impression that it is best practice to orient the wood grain such that it points outward to the body tube. I was unable to do this with my scrap piece.

After predicting a new weight based on design, I am now looking at a CTI H255. What motors have you guys flow this rocket on? I dont think I should go 5G quite yet.

View attachment patriot.ork

eeymontt · May 2, 2014

Just as I put the epoxy onto the centering ring, the fire alarm goes off and I have to rush into the rain clutching the rocket to my chest to hold the MMT in place. This happened while I was sliding the other centering ring into place for stability. Delayed by the false alarm, I managed to successfully glue the forward CR into the tube. Almost got glue into the fin slits, though. Going to go back later and add internal fillets with a wooden dowel applicator.

Next step is to sand down the fins and prep the aft CR. Still need to drill the pilot holes for the retainer and attach the rail button mount onto it.

Rex R · May 2, 2014

hint: get a shock cord protector if you want to fly it more than twice.
Rex

judo · May 2, 2014

+1 for shock cord protector. I got mine from Giant Leap IIRC. Any parachute vendor should have them.

Kehoes23 · May 2, 2014

eeymontt said:
Scuffed the glassine motor mount tube and marked, then taped, the region for the forward CR. After both sides of the internal fillets were epoxied, I glued in the eyehook. I also added a curved block of wood which hangs from the CR to be used as support. I will later drill one of the rail buttons into this block. I am under the impression that it is best practice to orient the wood grain such that it points outward to the body tube. I was unable to do this with my scrap piece.

View attachment 170874 View attachment 170875 View attachment 170876

After predicting a new weight based on design, I am now looking at a CTI H255. What motors have you guys flow this rocket on? I don’t think I should go 5G quite yet.

View attachment 170877

I flew mine on an Aerotech H238 a few times, I built it stock with a few oz of nose weight. I had a CATO on the last flight and bought another Patriot from the Insane Bovine. I have a J350 waiting for it when I get it done, the mods I did to the Patriot, fiberglass the body tubes, made it duel deploy and added about a pound of nose weight.
The build is looking good so far.

eeymontt · May 3, 2014

Rex R said:
hint: get a shock cord protector if you want to fly it more than twice.

I hadn't really been briefed about shock cord protectors. They sound like a sound investment. Luckily I can easily reach my arm down the BT to access my shock cord mount.

Kehoes23 said:
I flew mine on an Aerotech H238 a few times, I built it stock with a few oz of nose weight. I had a CATO on the last flight and bought another Patriot from the Insane Bovine. I have a J350 waiting for it when I get it done, the mods I did to the Patriot, fiberglass the body tubes, made it duel deploy and added about a pound of nose weight.
The build is looking good so far.

Thank you. It's now evident that a lot of good builds have turned their Patriot into a DD machine. Good luck on your rocket. I expect an impressive flight with a motor like that, and an almost two-second burn time.

Kehoes23 · Jun 28, 2014

ImageUploadedByRocketry Forum1403960368.002727.jpg

Here is the finished Patriot that I dubbed Spacetoaster, still have not launched it yet, been very busy with family and life. I'm thinking the next Red Glare I'll put it up in the air.

dgreger · Jun 29, 2014

Eeymontt, It is a great straight fast flyer, I have alot of pictures in my album of my build. Only thing I would do differently is not use the epoxy clay for fillets, Ive used it on two other birds and it cracks. Use some West Systems or other epoxy with a filler for external fillets.

Kehoes23 said:
View attachment 175916
Here is the finished Patriot that I dubbed Spacetoaster, still have not launched it yet, been very busy with family and life. I'm thinking the next Red Glare I'll put it up in the air.

Kehoes, Definitely bring it to next Red Glare, I'll be there with mine and will fly it on a J357 Blue Streak, so far 5 successful flights:
H225WT L1 Cert Single deploy to around 1400ft
I236 Blue Streak 2152ft DD
I345 White Thunder 2240ft DD
I195 Red Lightning 2126ft DD
I223 Skidmark 2158ft DD

Kehoes23 · Jun 29, 2014

Kehoes, Definitely bring it to next Red Glare, I'll be there with mine and will fly it on a J357 Blue Streak, so far 5 successful flights:
H225WT L1 Cert Single deploy to around 1400ft
I236 Blue Streak 2152ft DD
I345 White Thunder 2240ft DD
I195 Red Lightning 2126ft DD
I223 Skidmark 2158ft DD

View attachment 176018[/QUOTE]

Just curious, for your flight with the J357, how much nose weight did you use, for my J350 flight I put about 3 lbs of nose weight. I haven't launched it yet, just waiting for Red Glare.

dgreger · Jun 30, 2014

Mine has zero nose weight, hasnt needed any and shouldnt. The Av-bay and recovery gear up front have been plenty. Still has plenty of stability with the 5 Grain
J357 in it.

csoechtig · Jun 30, 2014

This is one of my favorite rockets. I built mine with 2 wraps of FG on the tubes + dual deploy. Also, I cut the bottom of the Nosecone for more room in the payload. here's the build thread...
https://www.rocketryforum.com/showthread.php?43643-Madcow-Patriot-Build-Thread

I366R - 2,234 ft
J275W - 3,802 ft
J415W - 5,935 ft
J275W - 3,554 ft
J275W - 3,650 ft

As you can tell, I love the J275W for this rocket. It is a semi-long burn flight that propels it to mid 3k range. But, it was pretty cool putting it up over a mile

...

[video=youtube;cnST90Sa6G4]https://www.youtube.com/watch?v=cnST90Sa6G4[/video]

Good luck with your build.

Build Thread - 4" Patriot (1/4 scale)

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