USR Sentra SRB 2.7"

[EMRR]

Received my 2.7 kit and the box is packed full of parts. First impressions are good.

I had thought that the 2.7 would not have fall-away boosters, but it does!

The kit has a hugh list of parts but in general:

Rigid Body Tubes
Solid Good Quality Balsa Nose Cones (3)
1/4" Balsa Fin Stock
Solid (thick) couplers
Ejection Baffles (3 <--- see question below)
Hardware
Elastic Shock Cords w/ 3-fold mounts
Motor Adaptors(1x 38 to 29mm, 2x 29 to 24mm)
Small decal sheet (no reference to SRB, says Easy Rider)
Various instruction pages and AIR reports
No Parachute(s)

Questions:

Jerry - I can not see (and I may be missing it) why I have 3x Baffle plates. One is clearly discussed in the assembly of the main rocket. Where do the other two go?

Also - No Parachutes, should there be? USR Webpage link is broken to check. Instructions reference "parachute recovery" which does not necessarily imply "parachute included".

Nick

 

[lalligood]

Nick,

I'll take a stab... Since all 3 parts (main boost & 2 side pods recoevery separately, wouldn't the pods need (& probably even more greatly benefit from) the baffle plates to help with protecting the recovery system)? (Answering a question with a question probably wasn't very nice or helpful of me though, was it?)

Instaship page says chute(s) not included. Seems like the side pods would be too small and/or light for chutes anyway. Streamer recovery for those...

That is quite a collection of parts! Wow. I can't wait to see the smaller version of the Micro Sentra SRB that I recently ordered when it arrives in the coming weeks

Please keep us abreast with your progress on this one!

 

[EMRR]

Originally posted by lalligood
I'll take a stab... Since all 3 parts (main boost & 2 side pods recoevery separately, wouldn't the pods need (& probably even more greatly benefit from) the baffle plates to help with protecting the recovery system)? (Answering a question with a question probably wasn't very nice or helpful of me though, was it?)

Well, I'm sure they are for the SRB's, however, I seem to missing that step in the instructions and just want to make sure.

Originally posted by lalligood
Instaship page says chute(s) not included. Seems like the side pods would be too small and/or light for chutes anyway. Streamer recovery for those...

Also, as far as the SRB's being small... let's put things in perspective. The SRB's are made up of 12" long, 2.7" rigid (heavy) tubing with a large solid Balsa nosecone, a 29mm motor mount with plywood centering rings and a single 1/4" balsa fin. Just these parts weigh 6.5 ounces.

I am impressed with this kit and am glad for a 2.7" version, verses the 4" version that I have wanted for more than 5 years.

The instructions point to a 36" parachute for the main Sentra and 2x 16" parachutes for the SRB's. I must have missed any fine print as to whether the kit would come with or without these parachutes.

Next photo. After some assembly the parts are coming together.

From left to right and top to bottom:

Bag of SRB mounts and launch lugs and 3 motor Adapters
3 motor mounts (2x 29mm for SRB, 1x 38mm for Sentra)
Upper coupler/bulkhead
2 SRB mount rings, 2 baffle plates (SRB?)
2 SRB nose cones
2 SRB 3-fold paper mounts for shock cords

Above the parts is the Upper template is the SRB tail cone template. The tube is cut and is formed into a tail cone. Interesting technique.

Nick

 

[rstaff3]

Yes, this sounds like a great kit and an interesting build!

 

[Jerry Irvine]

Originally posted by EMRR
Received my 2.7 kit and the box is packed full of parts. First impressions are good.

I had thought that the 2.7 would not have fall-away boosters, but it does!

The kit has a hugh list of parts but in general:

Rigid Body Tubes
Solid Good Quality Balsa Nose Cones (3)
1/4" Balsa Fin Stock
Solid (thick) couplers
Ejection Baffles (3 <--- see question below)
Hardware
Elastic Shock Cords w/ 3-fold mounts
Motor Adaptors(1x 38 to 29mm, 2x 29 to 24mm)
Small decal sheet (no reference to SRB, says Easy Rider)
Various instruction pages and AIR reports
No Parachute(s)

Questions:

Jerry - I can not see (and I may be missing it) why I have 3x Baffle plates. One is clearly discussed in the assembly of the main rocket. Where do the other two go?


Also - No Parachutes, should there be? USR Webpage link is broken to check. Instructions reference "parachute recovery" which does not necessarily imply "parachute included".

Nick

Baffles
There's the first error in the instructions

Parachutes
That is what did NOT arrive in time, and had I waited for them you would not have gotten your kit till mid-January. They will be sent along as soon as they arrive.

Decals
There are no Sentra SRB 2.7 specific decals yet, so on the suggestion of another customer, SOME decals were included so you could at least stick a USR logo on your rocket should your choose.

Going back to parachutes I had this grand plan that by ordering chutes way back in September and October (nylon and mylar) I would get them in time for a late December shipment.

Oops.

Jerry

 

[Jerry Irvine]

The SRB pods work on the principal of ejecting under full central rocket thrust. As such a baffle seems to ba a good precaution to allow beefy charges but less possible chute damage. One issue with any baffle is limiting motor length, and anybody who knows me knows I HATE to do that!

https://www.v-serv.com/usr/motors/h100.html

So until I get user feedback on whether to even suggest installing the baffle and if so at what motor length limiting position, then I reserve comment.

I am very happy to see these initial pictures and look forward to more just as much as everyone else does.

This kit is intended to include parachutes, at least for the first 10. I hope you concur delaying till after Christmas because of parachutes alone was not a good idea.

As for the Micro-Sentra SRB, before I left for vacation I received a notice the last remaining part is on the way. So those should go out as soon as I get back and feel like working a half day.

Based on the Weightlofter photos posted in another thread it seems my custoers are indeed of age to take a drink or two. I just may havre to take that lead as I enjoy a Merry Christmas and an especially happy new year.

Instahip has been a true blessing to all. This is the first year EVERYONE got a Christmas present as agreed. No almost shipped kits, no delayed shipments, no problems. God bless Instaship!

Merry Christmas

Merry Jerry

 

[lalligood]

Originally posted by Jerry Irvine
I am very happy to see these initial pictures and look forward to more just as much as everyone else does.

Ditto! It almost has me contemplating seeing if I can change my order for this one instead of the Micro Sentra SRB...

Originally posted by Jerry Irvine
As for the Micro-Sentra SRB, before I left for vacation I received a notice the last remaining part is on the way. So those should go out as soon as I get back and feel like working a half day.

No rush. It IS the holidays & EVERYONE should indeed enjoy them

Originally posted by Jerry Irvine
Based on the Weightlofter photos posted in another thread it seems my custoers are indeed of age to take a drink or two. I just may havre to take that lead as I enjoy a Merry Christmas and an especially happy new year.

Instahip has been a true blessing to all. This is the first year EVERYONE got a Christmas present as agreed. No almost shipped kits, no delayed shipments, no problems. God bless Instaship!

Merry Christmas

Merry Jerry

Instaship rocks. Belated merry Chrstmas & happy new year to you Jerry. Thanks

 

[lalligood]

Originally posted by EMRR
Above the parts is the Upper template is the SRB tail cone template. The tube is cut and is formed into a tail cone. Interesting technique.

That's the same as the USR El Lubbo. My advice: take your time. The cutting part is easy. It's the gluing part that will take some time to make a smooth fit, but it's worth the effort I assure you! It's a creative technique of creating transitions & shrouds that I'd like to incorporate into future scratchbuild projects.

 

[EMRR]

Originally posted by lalligood
That's the same as the USR El Lubbo. My advice: take your time. The cutting part is easy. It's the gluing part that will take some time to make a smooth fit, but it's worth the effort I assure you! It's a creative technique of creating transitions & shrouds that I'd like to incorporate into future scratchbuild projects.

Now you tell me! I will show you some pics later, but although I'm extremely optimistic about the final look (with filler and sanding). I am not happy with the initial because that rigid tube is tough to bend at the centering ring.

NOTE: I'm not knocking the technique, in fact, I like the new technique challenge!

More to come.

Nick

 

[Jerry Irvine]

Originally posted by EMRR
that rigid tube is tough to bent at the centering ring.

NOTE: I'm not knocking the technique, in fact, I like the new technique challenge!

Did you try the relief cuts discussed and illustrated in AIR-4 and lightly referred to in the instructons (IIRC)?

Feedback on optimum size relief cuts and minor tweeks to the shroud panel angles are very much invited. Once a shroud pattern is made, HUNDREDS of people will make THOUSANDS of shrouds with it.

Jerry

 

[EMRR]

Originally posted by Jerry Irvine
Did you try the relief cuts discussed and illustrated in AIR-4 and lightly referred to in the instructons (IIRC)?

Feedback on optimum size relief cuts and minor tweeks to the shroud panel angles are very much invited. Once a shroud pattern is made, HUNDREDS of people will make THOUSANDS of shrouds with it.

Jerry

Okay - no, but I can see (and I experimented on an already "dented" joint, how the relief cuts would have worked). I think the shroud panel should have (5) cuts instead of (4). I make this assessment by looking at where the crimps were.

Here is a photo of my results when NOT using the relief cuts.

For all those that have the SRB 2.7, read AIR-4 Page 6 Figure 11.

Again, I consider this a learning experience and am happy to have had this new technique introduced to me.

Regards,
Nick

 

[EMRR]

I used a hobby knife and trimmed away all the high spots.

I then soaked the exposed cardboard with CA.

Then I used Bondo Glazing to fill.

These are my SRB Tailcones after two applications of Bondo Glazing. They are going to finish up nicely.

 

[EMRR]

I installed my SRB Baffles 5" from the top. This leaves 4" of space for a parachute and leaves room for an 8" motor (if sticking out 1"). I don't anticipate ever using an 8" motor in my SRB's, but...

I installed mine by running a ring of glue on the inside, then sliding the Baffle Ring in place and pushing evenly on the center until it was 5" from the top. Left it standing upside down to dry.

I then dripped glue into the joint from the top opening and rotated the tube until I had an upper fillet/seal.

Next steps... fins.

Nick

 

[Jerry Irvine]

I am finding all these comments very helpful. It woud be somewhat trivial to include a 6 panel shroud pattern in the kit. The theory of using four is it is easier and sufficient, especially for a one finned pod.

I found the baffle placement comments logical and inclines me to leave the two extra baffles in the kit (this kit needs MORE parts ) and modify the instructions accordingly (it needs yet more pages )

I think the relief cuts should be in the instrructions since it is a steep angle shroud where they are critical. I would still look for feedback on relief cut width experiences.

Given the recent experiences with the new decals, I think I should get more kit specific decals of this style for more kits.

Several thousamd each of some 30 kits initially was a bit of a cost

But generally I am quite favoring the style of feedback I am seeing on TRF.

Jerry

 

[lalligood]

Originally posted by Jerry Irvine
I think the relief cuts should be in the instrructions since it is a steep angle shroud where they are critical. I would still look for feedback on relief cut width experiences.

I am presently working on a USR Stiletto & have pretty much finished the USR El Lubbo, which both use this same shroud technique. Even with the considerably longer shroud design and lesser angle of transition on the Stiletto, I have found that the relief cuts--not just single cuts, but the second stress relief cut is the best looking & easiest way to get smooth transitions. The best way is to make small cuts at first & then gradually increase them until the proper fit is achieved. It *IS* worth the effort (BTW, look for a new thread to be started in the next couple of days to chronicle my Stiletto build. I need to post some info about the El Lubbo too!)

Originally posted by Jerry Irvine
But generally I am quite favoring the style of feedback I am seeing on TRF.

Jerry

TRF: The only place on the internet to get constructive feedback about rockets without having to use a killfile

 

[Jerry Irvine]

https://www.v-serv.com/usr/kits/sentrasrb2.7.htm

 

[EMRR]

Hey, I recognize that coffee table!

Well, my finger may be permanently crooked after cutting and cutting and cutting through the 1/4" balsa and then the tube slots, but they are done.

Be sure to change your hobby knife blade 1st for the balsa, then again for the tube to get the best cuts.

I have to airfoil and then I'm going to put an epoxy/paper coating on them.

Then glue them in place, fillets, and then add the SRB hooks.

Nick

 

[lalligood]

Excellent pics, Nick I am looking forward to pics of the fins mounted in the central booster & then ones of the side pods!

Your posts here inspired me to change my recent order with USR to get the Sentra SRB 2.7 instead of the Micro Sentra. Bigger is better (And like I needed an excuse to buy a timer )

 

[Stymye]

cool .....looking forward to more of the build

also Thanks Nick,It's good to see the kit review forum used for what it was meant for ...reviewing a kit.

(mods is it possible to purge the not- reviews? theres a bunch of them.)

 

[Jerry Irvine]

Originally posted by lalligood

Your posts here inspired me to change my recent order with USR to get the Sentra SRB 2.7 instead of the Micro Sentra. Bigger is better

Already on the way, sir.

Bigger?

https://www.v-serv.com/usr/kits/OgeeQuadSRB6.htm

 

[lalligood]

Originally posted by Jerry Irvine
Already on the way, sir.

GOT IT! It was waiting for me when I got home...

HOLY COW, THERE IS A *TON* OF PARTS! I can't believe that Nick was able to take a picture with all of them at one time.

I should be busy for quite a while

 

[Jerry Irvine]

Originally posted by lalligood
GOT IT! It was waiting for me when I got home...

HOLY COW, THERE IS A *TON* OF PARTS! I can't believe that Nick was able to take a picture with all of them at one time.

I should be busy for quite a while

He had to pile them up. You spread them out for a photo

 

[lalligood]

Originally posted by Jerry Irvine
He had to pile them up. You spread them out for a photo

You asked for it

Look at all of that stuff!!!

 

[lalligood]

I should also mention (as well I will post these comments in the Vendors forum) about the super quick service from Jerry at U.S. Rockets. Long story short, I had a few incorrect parts & a couple others that were missing with my Sentra SRB 2.7, which I imagine could be easy to do seeing how there are over *60* parts in the kit--that's right, sixty plus parts! I dropped Jerry an email on Saturday explaining the situation & he obviously handled my issue quickly because I had a box sitting by the front door when I came home from work today (Wednesday). 3 business days to get stuff from one coast to the other--that's service!

A very happy USR customer

 

[lalligood]

I shouls also mention that I didn't leave those parts laying around very long at all after I took the picture...

All centering rings have been glued to the MMT tubes, motor adapters have been glued together, & bulkheads attached to the couplers. I'm hopping around a bit in the instructions but I'm checking off the completed items in the instructions as I go. (That's also not to say that I haven't read the instructions... In fact, I've read through them several times over the past couple of days while waiting for my correct parts!) I have started cutting all of the fins from the balsa stock. That's probably where I'll leave it for tonight though. More to come

 

[Jerry Irvine]

Originally posted by lalligood
You asked for it

Look at all of that stuff!!!

I finally got what *I* wished for.

Thank you.

Jerry

Now can I have general consumer HPR up to J in every hobby store in the country with mere adult access?

 

[lalligood]

Progress so far has been swift. Tonight I marked the main and both side pod airframe tubes for the fins, rail button placement (no lugs--main only), and hook placements. The central MMT was glued & filleted into place. All fins were match sanded for uniformity. Pod fins were airfoiled. One of the side pods has been cut for the boat tail shroud.

I've been jumping all over the place as far as following the instructions--I've been following them, just not in the order specified I'll wait until I have a little more done before I take/post any pics...

I'm hoping to be far enough along that I can take it with me to a launch on Saturday--not to fly! Just to show it off I s'pose

How's everyone else's Sentra coming along?

 

[Jerry Irvine]

Originally posted by lalligood


I'm hoping to be far enough along that I can take it with me to a launch on Saturday--not to fly! Just to show it off I s'pose

A "display" Sentra

Jerry

 

[lalligood]

Actually I'm planning to fly several USR kits (Banshee, Stiletto, El Lubbo, & Weightlofter) at tomorrow's launch...assuming that tomorrow's launch doesn't get rained out! Weather is *horrible* here today. (Actually we need the rain but I'm not keen on it raining right before a launch.)

With cooperative weather (& I'm thinking it will be), I'll make sure to get a picture of all my USR rockets, whether static or flying models, at the field to show off "the family".

 

[Jerry Irvine]

Originally posted by lalligood
Actually I'm planning to fly several USR kits (Banshee, Stiletto, El Lubbo, & Weightlofter) at tomorrow's launch...assuming that tomorrow's launch doesn't get rained out! Weather is *horrible* here today. (Actually we need the rain but I'm not keen on it raining right before a launch.)

With cooperative weather (& I'm thinking it will be), I'll make sure to get a picture of all my USR rockets, whether static or flying models, at the field to show off "the family".

Get a picture of the rain hitting those glistening paint jobs, and photos of the tears as folks realize they can actually GET USR kits quite easily.

Jerry