Estes Mongoose Booster

[BigRiJoe]

I have built three different Mongoose two-stagers, following the directions to the letter each time. The booster DOES NOT tumble and the front end has been crumpled on the first flight three consecutive flights. I have 3 Mongoose upper stages, wrote Estes, and am awaiting a new Mongoose gratis,which is greatly appreciated. Estes claims that they've had no other complaints about the booster problem; has anyone else experienced this; what's a good way to prevent it from happening again?

 

[DAllen]

I have built three different Mongoose two-stagers, following the directions to the letter each time. The booster DOES NOT tumble and the front end has been crumpled on the first flight three consecutive flights. I have 3 Mongoose upper stages, wrote Estes, and am awaiting a new Mongoose gratis,which is greatly appreciated. Estes claims that they've had no other complaints about the booster problem; has anyone else experienced this; what's a good way to prevent it from happening again?

I donno about Estes' claims...Maybe no one else wrote in about the boosters stability issues after burn-out. Even I have heard of this before with the Mongoose.

I think the best solution is to move the plastic fin-can on the booster half way up the booster to eliminate it's post-burn stability. This should not affect the overall stability of the rocket enough to matter. Then again, I am not sure how this kit goes together so I am not even sure if this is possible with that plastic fin can.

-Dave

 

[dragon_rider10]

I'm having a hard time picturing this. Are you saying the booster lawn darts because it's got a decent amount of tube extending forward from the fin can? I've heard of some folks having luck reinforcing their estes tubes with thin CA. Not sure how this would work on a pre-finished tube like the Mongoose's.

 

[DAllen]

That is exactly what I am saying. The booster is almost stable enough that could fly on it's own. Check out my attached "quick and dirty" RS file. The booster is marginally stable. Poor design really.

You could reinforce the BT with CA glue but that may or may not work. Personally my advice is to buy a different 2-stage rocket or modify the existing booster as I suggested.

-Dave

View attachment oop_estes_mongoose_booster.rkt

 

[n3tjm]

The mongoose is the remake of the estes scorpion two stage rocket. The original kit had a better design for the booster. Going from memory, the motor tube went all the way to the top of the booster and there was a centering ring there. I went to check up the instructions but the site seemed to be down, so I cant comfirm, buts that is how I built the mongoose's I had. Works like a charm,

 

[shreadvector]

Every new Mongoose I've seen for the last few years has had a booster stage that dangerously plummets in a stable manner toward the ground, resulting in a crumpled forward booster tube.

I alwys tell the flyer to contact Estes to report the problem and get a free replacement kit, but these are average Americans: they are afraid to "complain" and simply assume that many Estes models are 'junk'. I attempt to tell them otherwise and point to the excellent new kits with very good designs (including the newest 2 stagers and even the Eagle boost glider which can actaully glide away). Alas, most will not report problems and so the folks at the factory assume everything is fine.

The same is true for reporting problems to ALL manufacturers. But, for some problems there ARE reports that get through and immediate fixes are implemented (and by "immediate" I mean "as soon as the next batch goes into production" - it does not mean a 'recall').

 

[dpower]

Every new Mongoose I've seen for the last few years has had a booster stage that dangerously plummets in a stable manner toward the ground, resulting in a crumpled forward booster tube.

Yep, mine does this every time. On the bright side, the cardboard is amazingly resilient; they straighten right out and can be launched again and again.

 

[shreadvector]

I must not have observed the booster recovery. :blush:

Did you build the booster stages exactly per the Estes instructions? In other words, if you did anything different (i.e. better), then the booster(s) would not be improperly balanced like a 'stock' built-per-the-instructions 2-stage normal version.

Not true, you've seen my tripe staged Mongo-Mongoose launch (twice) at the Aug.30 Lucerne launch

and my boosters are still in perfect condition.​

 

[BigRiJoe]

I must not have observed the booster recovery. :blush:

Did you build the booster stages exactly per the Estes instructions? In other words, if you did anything different (i.e. better), then the booster(s) would not be improperly balanced like a 'stock' built-per-the-instructions 2-stage normal version.

That's my problem, I built all three boosters exactly as directed by the Estes instructions. I sent a link to this page to Estes customer service. Here's the message I received from Estes before posting here:Hello,

We have never had a report the booster stage was damaged, we will send you a replacement Mongoose.
Please allow 10 days for shipping.

Estes Customer Service

 

[Gillard]

i've had three mongooses, and the booster stage does get crimped, but not always, i've had a few flightsc were i have had not problems at all,
the reviews on EMRR suggest that crimping of the booster is fairly common.

 

[shreadvector]

Good point.
Yes and No.
The lower stage: yes, exactly per the instructions
The second stage: no, slightly modified (shortened) and motor placement also has been moved down to allow the motor to "stick out" beyond the fins to allow for the motors to be "taped" for staging.
I can see how changing the CG on the center stage would alter it's descent but the first stage was built stock.

Good data. I'm guessing that the stock booster is right on the hairy-edge of stable-vs.-unstable so you lucked out and yours tumbled perfectly. The middle stage as modified by you was perfect (i.e. unstable to tumble) and that sounds more like the older version of these I remember from many, many years ago when the construction was a bit different.

Does the newest version have you install and aft ring to prevent the booster engine from being ejected out the aft end? The extra ring will shift the motor upward 1/4 inch or so, and that moves the cg of the stage up just enough to allow those fins to guide it to a nice stable plummet toward the ground. The booster is much "happier" if a bit of the motor tube extends out the bottom of the fin can so the cg and cp of the stage with the spent motor casing are either right on top of each other or pretty close.

I wonder if Lucerne Wet Lake will be a Dry Lake by the time our March 28 launch date rolls around?

 

[Huge Blues]

I have a new version in the bag. The booster has an aft ring that places
the motor forward.