Hello: back building rockets.

[ecumsecumguy]

Hello:

I would like to introduce myself and ask a little advice. I was into Estes rockets as a kid (early 70's) and built several kits- including the original Alpha, Interceptor (that was COOL), Sandhawk, a few Goonybirds and several Centuri kits as well.

Well, I'm back courtesy of my 8 and 10 year olds - they are rabid rocket fans - we have recently built Big Bertha, CD Gemini, Cosmos Mariner, Canadian Arrow, and have a Super Bertha on the plate. Next as well will be a SwingWing transport. It's fun to be back. :) The kids are onto the demo version of Rocksim as well and are designing and test flying like crazy..my times have changed. :rolleyes: My 10 year old is digesting the Model Rocket Handbook whish we recently purchased in the US.

Here is a two general questions (of many hopefully) that I would like advice on. We are huge fans of V2 rockets and recently we won an older Maxi V2 kit on ebay. After seeing some posts here I'd like some advice on building it as strong as possible. Any advice on strengthening plastic fins, inner support rings, baffling, etc? I am wondering if we perhaps would have looked around for a different kit from one of the other companies - rather than this V2 (although we bought it now!). Any thoughts or feedback appreciated.

Secondly – and I am completely new to the newer engines this – what are the benefits of going to a different engine than the Estes D or E? Would a Aerotech RMS ( say a 24) fit in the V2? If so, what modification would be required? What are the pluses/minuses of RMS engines vs. Estes engines? Any thoughts appreciated!

Thank you – this post is a bit long. My apologies.

Randy

[A Fish Named Wallyum]

I've got some bad news for you, Randy. You're obviously one of us. Your pocket protector is in the mail. :D
Uh, but I don't have any answers for you. I'm kind of useless that way. :rolleyes:

[barone]

The Maxi V-2 has plastic fins? Who would have thought. I guess I should open mine a take a gander.......Yeah, I'm just like Bill..... :rolleyes:

Okay, mine has them plastic things too :( . I've heard of people using balsa to beef-up plastic fins on the Honest John and the latest incantation of the Saturn V. They cut the balsa and glue it between the two plastic halves of the fins. Of course, some shaping of the balsa may be required to achieve a good fit :eek: . Of course, you could always use the plastic ones as a guide to making balsa or plywood fins. But looking at the detail on them in the kit, I think I would go with the balsa between the halves :D .

As for engines....Sometimes the engines specified by Estes doesn't really work for the rocket. By that I mean, the completed rocket is sometimes heavier than the rocket Estes kitted. And then, of course, the recommended engine just doesn't get the rocket either a) going fast enough for a stable flight after leaving the launch rod or b) doesn't get it high enough for the parachute to deploy before the rocket plunges into the ground, breaking it into so many pieces that you can't believe you spent so many hours working on .....Oh, I digress.....been there, done that :( . So the RMS motors, and for that matter, single use Aerotech motors, give you an option of engine selection. But, a word of caution. Check the thrust curves and recommended max lift off weights for the motor. An E motor doesn't nessisarily(sp?) mean better performance than a D, nor F better than E. And you don't want a motor that accelerates so quickly that it rips your fins off. 24mm reloads will fit Estes D/E motor mounts (same size as a D engine). However, they usually have more kick on the ejection charge than the Estes motors so make sure you have an adequate shock cord....maybe twice the length of the stock shock cord. Also, you may want to consider going with a thicker walled stuffer tube. The standard BT-50 tube will burn through on you after a few flights, regardless of motor manufacturer. Some vendors offer a foiled lined tube to last longer.

Pros and cons? Well, the RMS system is high front end cost but the reloads are cheaper than buying single use (over the long run and assuming you don't lose your reload case). The reloads take longer to prep for launch but after you do it for a while, you get the knack. Wouldn't recommend letting little ones build the reloads unless you're there supervising but thats the same with single use motors anyway.

Good luck and keep checking your post. There's a lot of people out there who really know what they're talking about :o .


Don
NAR 53455

[A Fish Named Wallyum]

While this may not be specific to the V-2, I believe the HoJo uses the same kind of fins. You might want to give this site a check while you're at it. :cool:
http://www.ninfinger.org/~sven/rockets/hj.faq.html

[ecumsecumguy]

Thank you for the replies. I'm proud to be a "geek" enjoying a great hobby with my boys. :)
Great way to teach them patience, hobby skills and math as well. My 8 year old is firmly convinced he will work for ESTES as a designer someday. :)

My boys have already bought a few ESTES starter kits to give as birthday gifts for their buds. Good way to start others off.

We''ll take all the information we can get. We like to have fun and learn at the same time. Seems that this hobby has grown a lot since 1971. :rolleyes:

thanks again..I'm particularly interested in upgrading the Estes kits and fitting in the RMS motors. Adds yet another dimension to an already interesting hobby.

Randy

[CPMcGraw]

Thank you for the replies. I'm proud to be a "geek" enjoying a great hobby with my boys. :)
Great way to teach them patience, hobby skills and math as well. My 8 year old is firmly convinced he will work for ESTES as a designer someday. :)

Randy

Randy,

From one geek to another, welcome!

Your 8 year old doesn't have to wait for "someday" to become a designer, maybe just a few years more of school. I would highly recommend drafting and archetecture classes at the HS level when the time comes. Of course, math and science classes are generally useful, too... :D

With parts supply houses like BMS and SEMROC available today, most of us who build models these days aren't "locked in" to just Estes as a source. We're also not locked in to the simple and (generally) uninteresting designs out of Estes, either. If you remember the old Centuri designs, SEMROC is reproducing many of those kits now, with improvements. Sunward has the old Canaroc designs that will just blow you away.

And (tooting my own horn just a bit), there is the BARCLONE collection of non-kitted designs which is hosted here on the Rocket Shoppe server. BARCLONE is a place where you can try out your hand at design and have that design posted for everyone to try out. It's like the "Open Source" version of model rocketry... :rolleyes:

[Tau Zero]

Uh, but I don't have any answers for you. I'm kind of useless that way. :rolleyes:
Yeah, but you're still fun. ;) :D :cool:

Cheers,

--Jay
(Humming "Back in Black" to himself whilst he sits at the computer wearing his suit jacket, slacks, and white shirt) :eek:

[A Fish Named Wallyum]

Yeah, but you're still fun. ;) :D :cool:

Cheers,

--Jay
(Humming "Back in Black" to himself whilst he sits at the computer wearing his suit jacket, slacks, and white shirt) :eek:


I was planning to get out and fly today, but I woke up so sore from working on the house yesterday that I can barely move. I'm trying to get moving, but it's like driving in mud.
Bill
(Humming the CBS Sports theme while sitting at the computer in his underwear and a pink Oxford. :eek: )
:cool:

[EchoVictor]

(Humming the CBS Sports theme while sitting at the computer in his underwear and a pink Oxford. :eek: )
:cool:

Oooh, that's a mental picture I did NOT need! :p

Later,
EV

[A Fish Named Wallyum]

Oooh, that's a mental picture I did NOT need! :p

Later,
EV

Why do you think I wrote it? :D

[ecumsecumguy]

Well...I got my Maxi V2 kit and I'm wondering if it is worth spending the time or money upgrading. I'm debating buying a kit such as the Precision LOC 3.92" V2 kit and building the Estes as stock and running it on the recommended E motors once in a while.

Any thoughts? all feedback appreciated. I'd really like to put together a decent 4" V2 kit that would handle a RMS system.

[ghrocketman]

A few words of advice regarding your Maxi V2 (and all other Estes "Maxi-Brutes")...they barely fly decent on an Estes D12 let alone an E9 as the initial thrust of these motors is barely adequate for safe speed. I highly reccommend using the Aerotech RMS 24 in some of the lower thrust varieties (D-E-F BlackJack loads and some of the WhiteLightning loads) are fine in decently constructed (with proper fillets on the fins and motor centering rings) basically stock Maxi-Brutes. Just stay away from the BlueThunder F39 high-thrust loads unless you beef up the kit (epoxy construction and fillets). My Estes Saturn V flies really well on the RMS24 system, but is a relative dawg on an Estes D12; I would not even try it on an E9-4 as some claim will work. The RMS 24 would provide some really thrilling flights in the Super Big Bertha also. Quite frankly, I find the Estes E9 to be far too low in thrust for ANY sort of 4" diameter high-drag kit unless flown in zero wind with a LONG (around 5') launch rod.
Any wind causes the 4" rockets powered by an E9 to generally veer wildly off the intended flight path. Now on smaller (up to about 2.6") diameter rockets, such as the super big bertha, the E9 is a great motor.

[ecumsecumguy]

Thanks for the response!

Serendipity!

I also just happen to have a "super Big Bertha" in my closet that I just bought a month or so ago to give to my son for his birthday in March. Now I'm wondering if I should upgrade this as well to a 24 mm RMS.

thoughts? Recommended vendors for the upgrade of each?

[ghrocketman]

The "upgrade" you speak of for both would consist of using epoxy (instead of wood-glue) for construction as well as fillets and possibly using harder balsa for fins.
Pick a vendor....it is not that hard to find good epoxy (I use Pacer/Z-poxy or West System) or good hard balsa (any hobby shop).
Mid-power (D-E-F-G composites) is really not much different than regular model rocket construction...SOME (but not all) mid-power kits do use TTW (through the tube wall) fin attachment like used on Hi-Power (H engine on up), but that is about it other than using stronger adhesives.

[barone]

I also just happen to have a "super Big Bertha" in my closet that I just bought a month or so ago to give to my son for his birthday in March. Now I'm wondering if I should upgrade this as well to a 24 mm RMS.

thoughts? Recommended vendors for the upgrade of each?

I modified my Super Big Bertha for 29mm. Just bought a 29mm motor mount kit and tube connector from Aerotech. Seperation in the middle instead of nose cone. No other mods except using the long shock cords that come with the Aerotech kits. Flys great on Gs. Make sure you get the fins on straight and make a strong fillet. I think my fins aren't truely straight because I get a reallly spin stabilized flight...... :rolleyes:

Don
NAR 53455

[ecumsecumguy]

Thanks! I am going ot upgrade both. I have a couple of questions:

Will the maxi-v2 and the Suepr Big bertha both fly reasonably well on 24 mm motors? I'm not looking for super high flights, just something better than a a few hundred feet.

I'm debating adhesives with my engineering buddy..he is a big fan of the polyurethane glues out now and was suggesting that instead of epoxies.

I'd like to get a fin anlignment guide like the old ESTES one but they seem impossible to get. Apparently they are oop. Any ideas on a source for such a thing?

Any thoughts appreciated.

[ghrocketman]

Both of these will fly well with the 24mm RMS Aerotech motors. :p
The Super Big Bertha will also fly well with the Estes D12 and E9 in addition to the RMS 24.
The Super BB may approach 2500-3000 feet with the largest (F) 24mm RMS loads.
For the V2 you will probably max out at about 1500.
Note these altitudes are approximations/guesses; I did not run them through RocSim.
I too am an engineer and I would reccommend against the use of polyurethane type glues for rocketry use for several reasons:

1) They do not penetrate the "substrate" (wood fins, centering rings, body tube) as well as long (30+ min) cure epoxies do.
2) Common Polyurethane/Urethane glues do not have the bonding strength that a good epoxy does.
3) If urethane was better, the majority of the high-power community would already be using them; they DON'T.
4) Heat resistance between the two may be a toss-up.
5) Use an adhesive that has been well proven for rocketry, epoxy, and you will be flying :D ; don't do this and you may be venturing into an R&D area that may prove to have less than optimal results :( ; I would say you want your first large rocketry and RMS motor endeavors to be successful, not an experiment, correct :rolleyes: ?

If you really want to try urethane glues, I suggest you start with small rockets for this glue then work your way up to the bigger stuff (above C engine) that may (most likely) be stressed (shredded fins, motor mount separation from airframe, etc) to failure. :mad:

[ecumsecumguy]

thank You!

I appreciate the response. I'm learning by asking that's for sure. :)

I talked to one of the rocket shops about stiffening my Maxi-V2 fins..he suggested epoxy and micro ballons mixed in to fill the fins..sounds interesting.....luckily my friend uses both in his business. I'm thinking of trying it.

[CPMcGraw]

I'd like to get a fin anlignment guide like the old ESTES one but they seem impossible to get. Apparently they are oop. Any ideas on a source for such a thing?

Any thoughts appreciated.

Try using one or more instances of 0.05" thick matteboard, with a hole in the center matching the outer diameter of the tube, and slots cut for thickness of the fins. Just trim out the corners where the glue joint will be so it doesn't get "stuck" in place. This is much cheaper than locating one of those guides, and you can use the same technique to make any alignment guide you'll ever need.

I now include patterns in all of the newer BARCLONE plans to do this, as I find it works much better than the Estes jig. Did I mention, it's much cheaper, too...:D

[Doug Sams]

Thanks! I am going ot upgrade both. I have a couple of questions:

Will the ... the Super Big bertha both fly reasonably well on 24 mm motors?

The 2.6" and larger kits are good candidates for upgrading to 29mm. You can still fly them on 24's with an adaptor. That said, I'm working on a SBB with a 24mm mount, but added 8 smaller tubes for a nine motor cluster.

http://home.flash.net/~samily/SBB/SBB3.jpg
http://home.flash.net/~samily/SBB/SBB3.jpg

Fully loaded it will likely have four A10's plugged, four C6's popping the chute and a plugged E9 in the middle. On small fields, I should be able to fly it on four A10's, a D11-P and four A8's, B4's or B6's.

Unlike most Berthas, this one will need noseweight. Not much, but with all nine motors loaded, it's down to 0 CP/CG margin.

Doug

[Doug Sams]

I'm debating adhesives with my engineering buddy..he is a big fan of the polyurethane glues out now and was suggesting that instead of epoxies. Besides ghrocketman's good advice, I want to add that polyester glues expand which can make for unpleasant consequences. Yellow (wood) glue, thick and thin CA, and hobby (ie, 15 minute) epoxy pretty much cover most construction needs. Sometimes a little model cement is needed for joining two pieces of styrene. Other than that, I don't see the need for much else, especially glue that's so durned expensive. I 'bout got sticker shock looking at a bottle of Gorilla brand glue at the checkout counter the other day.

Doug

[Ltvscout]

The 2.6" and larger kits are good candidates for upgrading to 29mm. You can still fly them on 24's with an adaptor. That said, I'm working on a SBB with a 24mm mount, but added 8 smaller tubes for a nine motor cluster.

Fully loaded it will likely have four A10's plugged, four C6's popping the chute and a plugged E9 in the middle. On small fields, I should be able to fly it on four A10's, a D11-P and four A8's, B4's or B6's.

Unlike most Berthas, this one will need noseweight. Not much, but with all nine motors loaded, it's down to 0 CP/CG margin.
Whoa! That's cool! That looks like something that needs to be drawn up as a mini-plan set for BARCLONE, Doug!

[CPMcGraw]

Whoa! That's cool! That looks like something that needs to be drawn up as a mini-plan set for BARCLONE, Doug!

I agree, Scott & Doug. Seeing how the model has separate upper and lower body tubes, you could put a bulkhead in that upper section and call it a Super Ranger. That would allow for useful-load ballast instead of dead-weight ballast...

Have you tried this package on RockSim yet?

[Doug Sams]

I agree, Scott & Doug. Seeing how the model has separate upper and lower body tubes, you could put a bulkhead in that upper section and call it a Super Ranger. That would allow for useful-load ballast instead of dead-weight ballast...

Have you tried this package on RockSim yet?Thanks, guys. Rocksim says the CP is around the forward extent of the fins. With the 4 C's, 4 A10-PT's and an E9, the CG is in about the same spot. It will need 20+ grams near the NC to get a caliber of stability IIRC. (I don't have Rocksim installed on this, my new PC yet, and I'm too lazy to go fire up the old one.)

Fortunately, with the long moment arm, a little noseweight goes a long way.

I thought about a payload section, but elected to just glue the nosecone in and fill the seam. There's no bulkhead forward of the coupler, so much of the recovery harness can be stuffed in there in case the aft section doesn't have enough space.

Instead of using the stock gussets (Wouldn't they be stronger with the grain running radially instead of parallel to the BT?) I applied FNF fillets then glassed over them with strips of 4 oz cloth. The fins have a layer of tissue and dope. They're quite rigid near the glass - rock solid in fact - but still kinda flimsy near the trailing ends so I expect to put another coat of tissue and dope on.

BTW, the drawing for the MMT is here:
http://home.flash.net/~samily/stuff/BT-80Clusters.pdf The only variation is that two of the BT-5's ended up tight against the center tube while the other two BT-5's are gapped slightly farther outboard. (Reality meets math :)

Doug

[ecumsecumguy]

Well..after chasing a ESTES fin guide on Ebay up to $44 I have now decided to build a jig..this doesn't appear to be rocket science...I've got a bit of MDF, a few pieces of hardboard and a router......I've got a rough idea....anyone have a plan?

Great learning experience trying to fill a V2 vac molded fin with epoxy/micro ballons....I'm going to straight epoxy so it will flow in a little easier. Oh well live and learn.