DD Estes Mammoth

[rockets]

Yes, I did it. I bought a Estes Mammoth a couple of weekends ago, at a club launch. I was going to build it normally, but I decided it would be fun to make it DD. It's my first DD rocket ever. My dad owns a scroll saw, so we can cut out bulkheads! I went to the hardware store and bought what I need. I even got a 1/2 inch stick of PVC pipe for free!
I plan to fly it on a H115DM a H135W or a I205W, they're all DMS AT motors. First question, could I set it up where the ejection charge at apogee triggers the event, and the Dual Deployment computer takes care of the Main? Would that even work?? And second question, after the benefits of having RockSim9 Trial, it has now expired as of 1 1/2 weeks ago.
So, could somebody do a simulation on the motors above? Yes, I know I'd love to try OpenRocket, it sounds great, but I think you have all heard my story about when I tried to download it a couple of years ago. BTW, do you think it'll break mach one? It's a 29mm motor mount in a 2" diameter rocket:surprised:
Thanks,

 

[dhkaiser]

Saw a similar Estes rocket, an Ascender, launch on a H motor at MPW14. Tore the rocket apart right after ignition.

 

[rockets]

Saw a similar Estes rocket, an Ascender, launch on a H motor at MPW14. Tore the rocket apart right after ignition.

Hmm, I hope that doesn't happen to my rocket... I'm using 30 minute epoxy to re-enforce the fins.
I'm hoping for good results.
Thanks,

 

[TRFfan]

The body tube and fins will probably fail. 30 min epoxy is enouggh to get a strong fillet, not a strong fin. Most likely you will experence fin flutter and/or body tube failiure.

 

[TheAviator]

The body tube and fins will probably fail. 30 min epoxy is enouggh to get a strong fillet, not a strong fin. Most likely you will experence fin flutter and/or body tube failiure.

Body tube will be fine. I've used BT-101 on I motors. Fins may be an issue still, though. I would use a CTI 29mm Mellow load if I wanted to HPR one. I've seen people put G64s through them no problem.

 

[MaxQ]

Yes, I did it. I bought a Estes Mammoth a couple of weekends ago, at a club launch. I was going to build it normally, but I decided it would be fun to make it DD. It's my first DD rocket ever. My dad owns a scroll saw, so we can cut out bulkheads! I went to the hardware store and bought what I need. I even got a 1/2 inch stick of PVC pipe for free!
I plan to fly it on a H117DM a H135W or a I205W, they're all DMS AT motors. First question, could I set it up where the ejection charge at apogee triggers the event, and the Dual Deployment computer takes care of the Main? Would that even work?? And second question, after the benefits of having RockSim9 Trial, it has now expired as of 1 1/2 weeks ago.
So, could somebody do a simulation on the motors above? Yes, I know I'd love to try OpenRocket, it sounds great, but I think you have all heard my story about when I tried to download it a couple of years ago. BTW, do you think it'll break mach one? It's a 29mm motor mount in a 2" diameter rocket:surprised:
Thanks,

Body tube will be fine. I've used BT-101 on I motors. Fins may be an issue still, though. I would use a CTI 29mm Mellow load if I wanted to HPR one. I've seen people put G64s through them no problem.

I take it you will cut your own bulkheads for the Av Bay....ok. Good.

When this conversation started I went to the LHS and opened up one of those Estes Mammoth kits to take a look.
BT looks VERY thin walled to me.
Nice metallic paper finish though. LOL
The fins are plastic...you'll want to think about how you will do the fillets on those plastic fins (epoxy to plastic adhesion).

I didn't get a look at the centering rings for the motor mount...my guess is an H117DM, H135W or a I205W will subject those to a bit of abuse once they light up.
Perhaps you could put some couplers along the inside of the BT to buttress up against the CR and also thicken the internal BT.

Doing anything traditional, like FG on the outside of the BT, would require pulling off all that shiny paper.

Regarding the ejection at apogee...I've used motor ejection at apogee as a back up to the electronics with the main via electronics ejection at the selected lower altitude...(just make sure that IF you still have an electronic fired apogee ejection - it doesn't go off the same time as the motor delay ejection at apogee - that will be fun to figure out).

 

[rockets]

Yeah, the fins are what I'm concerned with. Maybe I should try a non HPR motor with a high thrust rate, like the AT G80T. If it holds together, I'd try a DMS H115DM, and there is not much thrust difference.
Thanks,

 

[chris m]

Some estes kits can do a very small H . Get a mad cow or loc kit and not have a problem . Stay away from plastic. Saw them on special and was going to get a few to put away but plastic fins

 

[jadebox]

My wife built and flew a Mammoth. She added fake fur to the fins making it a Wooley Mammoth! Having helped her build it, I agree with the others. The Mammoth flies nicely on the recommended Estes F15 black powder motors (nice, slow lift-off and long burn). It might be okay on a longer-burning G motor. But, I wouldn't subject it to an H (unless you can find something like a mythical H33).

-- Roger

 

[dhbarr]

I sent a mostly stock Mammoth up on a g64, no fillets, BSI 15min epoxy. No problems observed until a tree ate it along with my JLCR :-(

My only two mods were to run tape over the front fin seam, and to run tape on both sides of each BT joint. Gluing in only the bottom of both couplers let me Z-fold it for transport, a single wrap of masking tape over the joints for flight.

 

[MaxQ]

Yeah, the fins are what I'm concerned with. Maybe I should try a non HPR motor with a high thrust rate, like the AT G80T. If it holds together, I'd try a DMS H115DM, and there is not much thrust difference.
Thanks,

Based on a quick look....the difference between the G-80 and the H115 is 137 NS total impulse with a 22.5 lb peak thrust (G-80) vs. 172 NS total impulse with a 30 lb. peak thrust (H115).
(You can check the numbers here: https://www.offwegorocketry.com/ind...1_242&osCsid=3e4a89b38c79a8994b110f7285061902 )

Maybe not a significant difference in relative terms with the bigger motors out there - but again, when dealing with the Estes components you are basically doubling the motor thrust above the stock kit recommendation (E-16 and F15).
While it can probably be done, the question is what reinforcing would be needed to do it, and do it repeatedly before you find "the speed of cardboard" as they say.

https://www.rocketreviews.com/estes---mammoth-9757.html



I'm sure any number of guys here could do the mods and pull it off - if challenged in that direction ..... Apogee has an Aspire kit they claim can go Mach 1 and /or a Mile high but with the appropriate modifications.
(of course it is small - and not a DD kit)

 

[MaxQ]

Maybe you can get that TRM - mentor to give you some advice on some light mods to get you where you want to go.
Doubt you will be getting a Mongoose 38/Black Hawk 29 min. diam. performance out of an Estes kit.

If getting into DD is really your objective, you may not even need to worry about going to an H or I motor in a narrow rocket, you can probably get the altitude you would need to work the dual deployment with less motor.
Certainly don't need to go to an I205. (Andrew - You sure you aren't still in that minimum diameter Mach busting mode here?)

That said...when building with light weight materials and pushing the motor size...
I've got a scratch built scale model made out of poster board, foam core, and some stock Loc components modified as needed.
It was inexpensive...so much more affordable than exotic (heavier) materials.
I never intended it to go Mach or a mile high, it was built to suit a "scale like" performance. It was lots of fun too.

Came in at 8.5 inch dia. and 3lb. dry wt. - it just did its fifteen flight at LDRS.....all on H motors (with some occasional outboard air starts).
Motor mount in the foam core centering ring (reinforced) has survived all those flights.
But I'm not curious enough to put an I or J in it. to find out if it won't.

 

[Barkley]

I have a mammoth (among other things) on the bench at the moment. I'm going to give the BT a wrap or 2 of FG, replace the centering rings with FG plate, and tip to tip the plastic (although I may just replace the fins). I plan on putting a 6 grain H in it to start, then max out the 29mm motor mount.

 

[MaxQ]

I have a mammoth (among other things) on the bench at the moment. I'm going to give the BT a wrap or 2 of FG, replace the centering rings with FG plate, and tip to tip the plastic (although I may just replace the fins). I plan on putting a 6 grain H in it to start, then max out the 29mm motor mount.

Sounds like a fun challenge.

You planning on dual deployment ?

 

[MaxQ]

I sent a mostly stock Mammoth up on a g64, no fillets, BSI 15min epoxy. No problems observed until a tree ate it along with my JLCR :-(

My only two mods were to run tape over the front fin seam, and to run tape on both sides of each BT joint. Gluing in only the bottom of both couplers let me Z-fold it for transport, a single wrap of masking tape over the joints for flight.

What were the stock kit centering rings like?

 

[dhbarr]

What were the stock kit centering rings like?

Thick chunky plastic, they're plenty study. Body would buckle before anything else, likely right above the fincan.

 

[Barkley]

Sounds like a fun challenge.

You planning on dual deployment ?

Planning on motor eject with a JL chute release. I don't launch anything bigger than an F without it.

 

[tomsteve]

Andrew, you, sir, are one ambitious young man and that is awesome! I think you will find with the mammoth is that it is extremely light and will rip a hole in the sky on a G80.

Yeah, the fins are what I'm concerned with. Maybe I should try a non HPR motor with a high thrust rate, like the AT G80T. If it holds together, I'd try a DMS H115DM, and there is not much thrust difference.
Thanks,

 

[TRFfan]

replace the fins with plywood. Reenforce the body tube right above the fincan with coupler tubes.

 

[TheAviator]

replace the fins with plywood. Reenforce the body tube right above the fincan with coupler tubes.

I guarantee the body can take a high-power motor. I've thrown high-thrust H motors through standard BT-60 with no problems whatsoever.

 

[Initiator001]

I have built and flown all the Estes PSII E2X kits using motors from D12-3 y to an AeroTech G74-9 Economax (Baby 'G' motor).

In the case of the Mammoth I have built and flown three of them.
The fins on the Mammoth are through-the-wall to beefy plastic centering rings. I've never had a fin failure.
The body tubes are thicker-walled then traditional model rocket tubes (BT-50, BT-60, etc.).

There should be no problem flying on an AeroTech G80 motor or a low/mid average thrust 'H' motor.

Just keep the model below Mach and it will be fine.

 

[rockets]

Well, the electronics bay is built, well, except for the ejection charge well. The rocket is probably estimated at about almost a pound. I bought a pack of F20-7W's and I will fly it on that first, to make sure my dual deployment system works. This rocket & my MD rocket (see my thread) will fly in the fall.
Thanks,

 

[MaxQ]

The rocket is probably estimated at about almost a pound. I bought a pack of F20-7W's and I will fly it on that first, to make sure my dual deployment system works.

If you can keep it to a pound then the F20 appears from online specs to be ok.
You have the electronics and battery weighed in with the motor ?


Motor Type: F20-7W
Delay: 7 seconds
Dimensions: 1.18 x 2.87"
Motor Weight: 2.6 oz. (76 grams)
Propellant Weight: 30 grams
Propellant Type: White Lightning
Propellant Effect: Crackling White Flame and Smoke
Total Impulse: 14.6 lbs./sec., 65 N/sec.Average Thrust: 4.5 lbs., 20 Newtons
Burn Time: 3.4 seconds
Peak Thrust: 11 lbs., 48.9 Newtons
Maximum Recommended Lift-Off Weight: 16 oz., 450 grams
Aerotech Product Number: 62007

 

[Nick@JET]

H45 motor would be nice, even though only shows in 38mm - I have a 29mm Aerotech H45 maybe you can find one. Long burn 6 sec easy push, tracker needed. Not sure how I wound up with 29mm - came with some used stuff I bought.