How much thrust can a standard Estes BT-60 take?

[PunkRocketScience]

I picked up a second Estes Renegade the other day with the thought that I would up the motor size big time.

When goofing around with my first kit, I found that the tube fit my Pro38 casings perfectly...you can see where this is going, can't you? Would a standard Estes tube take the thrust from a 1 grain Pro38? If not, would you have any recommendation on what weight of glass to use? I plan on at the very least doing glass on the fins and/or upgrading them to ply.

Can't wait to see the RSO's face when I walk up to the table with this one !

 

[Silverleaf]

I'd bet that simply glassing it would be a safe method to increase the odds of its survival, but my main concern would be stability.

Perhaps https://www.rocketmaterials.com could give you some definitive answers on this query. 8)

Cheers,

 

[DynaSoar]

Originally posted by RocketmanTM
I picked up a second Estes Renegade the other day with the thought that I would up the motor size big time.

When goofing around with my first kit, I found that the tube fit my Pro38 casings perfectly...you can see where this is going, can't you? Would a standard Estes tube take the thrust from a 1 grain Pro38? If not, would you have any recommendation on what weight of glass to use? I plan on at the very least doing glass on the fins and/or upgrading them to ply.

Can't wait to see the RSO's face when I walk up to the table with this one !

Thrust, yes. The Pro38-1G G79 only peaks at 21.5 lbs. A chunk of BT60 can stand that much weight easy, and force is force regardless of direction.

The problem is flex and Gs. How much will 1.5' of BT 60 (Renegade minus nose, minus the amout of body surrounding motor) flex under the G force at non-zero angles of attack, and how much flex it can handle due to airflow.

The rocket attached is 5' of BT60. The whole thing weighs <12 oz. Half that is the motor/fin/boat tail assembly, half the rest is the payload and recovery gear. The 5' of BT60 is cut into 4 sections and glued by 3 couplers. That keeps any one section from flexing too much.

It flew on an F21 with no problems. The sim says it did 400 MPH at 1.8 seconds with peak acceleration of 35 Gs. I think those couplers act as tube stiffeners and keep any bending (and I'm certain this thing bends) from reaching to tight a radius, where drag can cause the nose to slow and the fins not.

Glassing also stiffens the tube. I think it'd be way more than you'd need for the little amount of tube needing stiffened.

A Renegade would need more stiffening than most because of that assymetrical nose. And the acceleration it'd undergo would probably be way more problem to those fins pods and fins.

 

[Jerry Irvine]

The definitive Estes shredder on the margin motor is the 29mm 160G80.

That partucular motor has been available over the years from AT, USR, Plasmajet and IBCo with similar results.

Jerry

 

[DynaSoar]

Originally posted by Jerry Irvine
The definitive Estes shredder on the margin motor is the 29mm 160G80.

That partucular motor has been available over the years from AT, USR, Plasmajet and IBCo with similar results.

Jerry

Mine's only 24mm. Would a G110 do?

No, it's not "legal". It's out of cert. I wouldn't fly a test like this at a sanctioned launch anyway.

 

[Jerry Irvine]

Originally posted by DynaSoar
Mine's only 24mm. Would a G110 do?

No, it's not "legal". It's out of cert. I wouldn't fly a test like this at a sanctioned launch anyway.

To compare motor X with motor Y you would have to do a velocity vs time chart. Since it is speed that kills, and a 29mm 160G80 is the motor that defines the threshold best, you have to approximate thet speed and thrust combo (or greater) to shred Estes BT-55 and BT-60 "most of the time".

Jerry

These days I assume any useful or fun or historically popular motor is not certified. Very few exceptions to the rule to confuse people.

 

[astronboy]

I built a BT-60 based rocket using only ESTES parts, balsa and yellow glue this summer. It was specifically designed for the Ellis Mtn G37-10. The BT held up , but the TTW fins actually ripped out from their roots. they did not shred, but fluttered down intact.

I plan on building a second version with the only changes being a lengthened BT, using a stage coupler material inside the fin can area to prevent flutter, and epoxy to attach the fins.

Phred

 

[artu]

Originally posted by astronboy
I built a BT-60 based rocket using only ESTES parts, balsa and yellow glue this summer. It was specifically designed for the Ellis Mtn G37-10. The BT held up , but the TTW fins actually ripped out from their roots. they did not shred, but fluttered down intact.

Phred

Hi, I fly many rockets on the Ellis G37 and G35 motors.
They are my crowd pleasers on a budget.

The Semroc Jaguar is my Favorite for either of those motors.
I use just yellow glue on the Jaguars.

The entire line of SLS Semroc are great for F & G motors.

If you use lite plywood fins instead of Balsa, the fins wont fail at the root like the balsa did.

BTW, that's the same place Plywood fins fail at high thrust on HPR motors.

I had a very light 4" rocket with plywood fins fly on a J570 motor.

On Board video showed the first fin snap right off at the root at max thrust.

It had held up before fine to Ellis J228

 

[PunkRocketScience]

Sweet...glad to hear that the tubes can take it. I figure that I will be lining the main body with tube couplers to beef it up. With all of the fin area on a Renegade, I'm not real worried about stability, but I will swing test before launch. I'll post pics when it goes!