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CPMcGraw
10-10-2007, 05:54 PM
To start this thread off, I want to make it clear that I am not a big fan of plastic in model rockets, although I recognize there are applications where plastic may be the only way to achieve a desired result. We have been exposed to plastic nose cones for about as long as there have been model rockets; some are still with us today. A well-made plastic nose cone offers certain advantages that a solid balsa cone cannot, such as a way to place ballast as far to the tip of the model as possible when needed, or even as an expansion of available payload-carrying area.

The new D-R-T is an engineered kit with plenty of plastic. The entire lower body section including the fins is made from an engineering plastic (BASF Ultraform, perhaps?). The nose cone is a detailed blow-molded piece with a thin raised parting line showing the break of the mold. The remainder of the kit is made from sections of thick-walled paper tube.

The plastic components have a measure of mass to them, and this mass is in the worst possible location on a model rocket: the tail.

Now, in spite of all this, I am suitably impressed with the overall quality of the kit as-packaged. When the major components are fitted together and the model is standing upright, it is a clean design with lots of detail. What I like about the kit is the thick-walled tubes, both the main body sections and the internal motor tube. I can easily see using 24mm RMS reloads in this design.

But I have to wonder about some of the design compromises. First, the use of the older folded-paper rubber strip shock chord method instead of a modern Kevlar & elastic shock chord. I was stunned when I saw that rubber strip, and realized I would have to make a change to something far more substantial. A second compromise concerns the top end of the motor tube. It is completely unconnected and "floating" over a length of about 12" from the top of the thrust block. There are two plastic rings which, together with the plastic lower body pieces, form the motor mount. This tube is long enough for "E" motors, but is also long enough for motors of extended length if the thrust block is eliminated or glued farther up. What is the reason for the extra length if it is not going to be used either as a long mount or as part of a "stuffer tube" volume reducer? A centering ring at the top of the tube would reduce the expansion volume for the deployment charge. It would also reduce any "vibration" of the tube during the thrust phase. This needs to be my second modification.

One thing I am looking at is to adapt the nose cone section for one of those Aiptek cameras. There is plenty of area inside the payload body to mount one of these and include plenty of padding.

I'll post some build shots as I move along.

snaquin
10-10-2007, 07:02 PM
Craig,

I bought one myself during last weeks 40% off at Hobby Lobby. My first impression too was plenty of plastic, but I really do like the detailing.

I became interested after seeing a How-To-Classroom build thread on Rocketry Planet where Darrell modified his for 29mm motors. I found it to be an interesting article.

http://www.rocketryplanet.com/forums/showthread.php?p=4092

I'm planning to build mine stock like the kit instructions suggest but I may add nose weight after I enter it all in RockSim and see how it fairs simulated with 24mm reloads and single use composite motors. I'm planning E and F motor flights with mine. I did pick up a bottle of the Tenax 7R plastic welder to try on the styrene fins and fin can.

A guy at our last Winnsboro launch had a DRT built stock and flew it on an F24. Overall I think it's a nice kit ..... even nicer at 40% off retail. The heavy duty tubing, large detailed blow-molded nose cone and nylon parachute are all great features you wouldn't normally find in an an Estes kit.

I look forward to your build shots as it will probably be a while before my DRT comes up in the build queue.

;)

.

CPMcGraw
10-10-2007, 07:06 PM
Craig,

I bought one myself during last weeks 40% off at Hobby Lobby.

That's how I got mine. It's worth the ~$20 price with the coupon, but I'm hesitant about picking one up at the full price...

...I became interested after seeing a How-To-Classroom build thread on Rocketry Planet where Darrell modified his for 29mm motors. I found it to be an interesting article.

http://www.rocketryplanet.com/forums/showthread.php?p=4092

Thanks for the link. I need to read it myself...

tbzep
10-10-2007, 08:32 PM
I picked one up with the coupon also. I probably would never have bought it without it being 40% off.

I think the thing is waaaay overbuilt to be flown with an Estes D or E motor. Once again I refer to the much thinner walled kits from FSI where people flew them with F100's and today fly them with G class composite motors. It's way down on my build list so I may not get around to building it for a long time.

CraigF
10-10-2007, 10:07 PM
Can any of you compare this DRT to the previous Estes one? I don't have my E DRT kit yet, in fact my whole AC Supply order seems in limbo ($23.45 there). The old version only had the NC made of plastic and is fine on a D or AT E. I was actually hoping the current incarnation would be more suitable for an F, as the old one was pretty lightweight construction when built stock. I was hoping the fin plastic would be something like ABS, a bit more flexible/less breaky than the styrene or whatever plastic they typically use.

CPMcGraw
10-10-2007, 10:33 PM
Can any of you compare this DRT to the previous Estes one? I don't have my E DRT kit yet, in fact my whole AC Supply order seems in limbo ($23.45 there). The old version only had the NC made of plastic and is fine on a D or AT E. I was actually hoping the current incarnation would be more suitable for an F, as the old one was pretty lightweight construction when built stock. I was hoping the fin plastic would be something like ABS, a bit more flexible/less breaky than the styrene or whatever plastic they typically use.

The problem with being more flexible is that fins tend to be flexible at times and/or locations where we wish they weren't. As far as the DRT fins themselves, they're nicely done, with minimal flash along the parting lines. You will need to dress the root edge with flat files and polishing paper, but that's no worse than when you build a static model airplane. But as TB just said, this is really not a "D" and "E" class model. It would feel much more at home with "F", "G", and maybe even low "H" power. If we're talking about those power levels, then the weight of the fins would not be an issue - they're not that much heavier than good AC plywood.

One thing I would have felt better with would have been some longer tabs to fit through the mount. The tabs on these fins are adaquate for going through the thickness of the plastic mount section, but no farther. An additional ring about mid-way between the two kit rings, with deep tabs slotted to accept that ring, would have been much better.

Comparing this model to the original #1944 version, this one is larger (1.8" diameter versus 1.64") and more rugged. The older design should reach higher altitudes being lighter, and still taking 24mm "D" motors. The original also used balsa fins and had less detail.

CPMcGraw
10-11-2007, 09:24 PM
OK, a correction in my earlier post is in order here. I said that the motor tube was "floating" in the model at the top, and only had rings at the bottom and top of the lower body section. Well, I looked again at the instructions. This time, I actually read some of them... :o

There are two plastic rings. The first one which fits into the bottom of the lower body section and into which the motor tube is glued; and another ring which is attached to the mid-body coupler. When the lower body section is glued into the first main body tube, the coupler is glued into the top and onto the upper end of the motor tube. This actually forms the top bulkhead for a stuffer assembly. The upper end of the plastic lower body section has a formed ring which holds the motor tube centered and secure.
Now I am more suitably impressed by the thought that went into this new model. Having a plastic upper ring provides a solid base for the addition of a Kevlar thread mount.

One thing that might catch RD's eye is the constant recommendation in the instructions for using "plastic model cement" to attach the plastic pieces to the paper tubes. This is one of those few applications where a thin smear of epoxy on the mating pieces would be better. Be sure to rough up the plastic where the epoxy can get a better bite, and wipe away any excess before it cures.

A Fish Named Wallyum
10-11-2007, 11:21 PM
I noticed the D-Region kit at one of my local Hobby Lobbys a couple of weeks back, and clipped the coupon last week with plans of picking one up. I thought they'd be common, but the second store I went to didn't have one. I wound up with one of the new "screw-together" kits that I'm building for the 4 year-old son of a friend. (He wants to put Cars stickers on it. :rolleyes: Pardon me for allowing him to desecrate a classic.)

CPMcGraw
10-11-2007, 11:42 PM
I noticed the D-Region kit at one of my local Hobby Lobbys a couple of weeks back, and clipped the coupon last week with plans of picking one up. I thought they'd be common, but the second store I went to didn't have one. I wound up with one of the new "screw-together" kits that I'm building for the 4 year-old son of a friend. (He wants to put Cars stickers on it. :rolleyes: Pardon me for allowing him to desecrate a classic.)

Iz he a Mater, too? ;)

CPMcGraw
06-14-2008, 01:37 AM
OK, well it's been long enough sitting partially together waiting for me to get busy building this bird, so here is the first installment.

I began by attaching the lower plastic centering ring to the central core tube with 15-minute epoxy. Very thin smears on both mating surfaces, and only in the area of contact. The thrust ring was installed with yellow glue, as per typical construction.

As this was curing, I attached the upper centering ring into the coupler with epoxy; again, thin smears on both surfaces, contact areas only.

To assemble the plastic-to-plastic parts, I used the Tenax-7R cement. Absolutely the best cement I've used for plastic, even better than the Plastruct (if that's possible). I'm sold on it now. The two lower body shells trapped the lower ring in a molded groove, and had a neck at the top to hold the tube. I epoxied the neck joint, and T7R'd the lower ring and body halves. The parts were held together with moderate pressure using some small bar clamps until the T7R had cured.

Next, I epoxied the lower main body tube to the top of the plastic section, again with thin smears. I was seriously trying to control excess weight, and I think I probably used way less than 2 tenths of an ounce in this process.

Finally, I epoxied the upper plastic ring to the core tube, and yellow glued the coupler into the top of the lower main tube.

Basically, this is a step-for-step following of the stock instructions to this point. I have not glued the fins into the lower unit yet, as I want to do some pre-finishing on the tubes first. I am also looking at how to mount a strong Kevlar harness in the upper main tube, and I'm thinking about a baffle.

Two words, however, are nagging at my feeble brain as this thing comes together: HEAVY BRICK.

I'm not convinced a D12 is the right motor, neither do I think the Estes E6 is right for it; thankfully there is a 24mm RMS package I can try. I think a reload would do it justice and still keep it in the field where I fly.

I'll take some pictures as I do the deviations from the plans, like the baffle.

Would someone who has built and flown this bird please post some actual finished model weights? Estes says just under 10 ounces. I think it's higher. Some real-world numbers would be helpful.

Mikus
06-14-2008, 07:36 AM
Would someone who has built and flown this bird please post some actual finished model weights? Estes says just under 10 ounces. I think it's higher. Some real-world numbers would be helpful.

Your in luck, mine is out and prepped for flying today. Out with the motor and onto the wife's kitchen scale it went.

11-1/4 oz or 324g. It does have a little barf in it but that shouldn't add too much weight. Other than a snap swivel and longer shock cord, it is built stock.

snaquin
06-16-2008, 07:08 PM
I'm not convinced a D12 is the right motor, neither do I think the Estes E6 is right for it; thankfully there is a 24mm RMS package I can try. I think a reload would do it justice and still keep it in the field where I fly.

Craig,

Not sure the limitations of your field but since you are considering the 24mm RMS the recommendations for the AeroTech IQSY Tomahawk should suit the Estes D-Region about right .....

I have two of the Rouse Tech 24/40 motors that I bought from What's Up Hobbies and I think you'll be hard pressed to beat his $39.95 price for the Rouse Tech 24/40 motor.

http://stores.whatsuphobby.com/-strse-124/RouseTech-24-fdsh-40-motor-system/Detail.bok

There's a bunch of successful flights for this model logged on EMRR with Estes black powder D and E's but since I have both single use E's and E reloads for the 24/40 I'm not even considering flying mine with Estes D and E's.

http://www.rocketreviews.com/reviews/kits/est_d-region_tomahawk.shtml

Good luck with your build. Looking forward to your progress and pics. {My D-Region is still in the bag but I'm looking forward to picking another up at HL with a 50% off coupon because it is such a nice kit}

.

dwmzmm
06-16-2008, 10:01 PM
Your in luck, mine is out and prepped for flying today. Out with the motor and onto the wife's kitchen scale it went.

11-1/4 oz or 324g. It does have a little barf in it but that shouldn't add too much weight. Other than a snap swivel and longer shock cord, it is built stock.

I think Mikus flew his on an E9 this past Saturday, and it flew pretty good. Pics below tells
the story....

The fourth pic is Mikus' back as he's looking at his descending D Region Tomahawk.

CPMcGraw
06-16-2008, 10:20 PM
...11-1/4 oz...
...I think Mikus flew his on an E9 this past Saturday, and it flew pretty good...

Thanks, guys! I haven't weighed mine yet, it just feels heavy. I've also got the Estes Rubicon (still building), which is heavy (but not quite as heavy) compared to a "typical" "D"-"E" model. What do you estimate the "E" flight reached?

...since you are considering the 24mm RMS...Rouse Tech 24/40 motors...hard pressed to beat his $39.95 price...

This is what I was thinking about, a standard-length 24mm reloadable, with a low-end E. I see an E11 and an E18 that look interesting, and which might stay in the recovery zone. Still need to set up a RockSim test for this one to be sure.

Thanks, Steve, for the heads-up on the RT case...

Mikus
06-17-2008, 09:50 AM
I've also got the Estes Rubicon (still building), which is heavy (but not quite as heavy) compared to a "typical" "D"-"E" model. What do you estimate the "E" flight reached?

I'd say about 750-800 ft. It's a great flyer for all that weight.

You might want a bigger parachute because it likes to pop fins and I'd just go ahead and leave off the fake nozzles unless you want that scale appearance. After about 10+ flights they'll be melting and popping off most likely.

Go ahead and use a bigger chute for the D-Region too, it also loves to pop fins. :rolleyes:

CPMcGraw
06-17-2008, 12:29 PM
I'd say about 750-800 ft. It's a great flyer for all that weight.

You might want a bigger parachute because it likes to pop fins and I'd just go ahead and leave off the fake nozzles unless you want that scale appearance. After about 10+ flights they'll be melting and popping off most likely.

Go ahead and use a bigger chute for the D-Region too, it also loves to pop fins. :rolleyes:

Thanks, Mikus. I sorta figured the fins would be a problem. And if I go with RT on the Rubicon, those nozzles might not make it to 10. :(

You get the feeling that there just was not enough "R" in the "R&D" before either of these went into production? :o