Der Red Max handle D16?

[Art Upton]

I've posted this before... but still interesting:

This happened to my attempt to push and Estes Generic E2X as hard as I possibly could...(D20-8). the tube split allowing the nose to collapse back into it. Obviously the ejection charge didn't get it pushed back out. Landed about 300ft away. It didn't get too high with all the extra drag from this on the front end....that's the only reason I was able to track it on a perfectly cloudless day with sun at a good angle. Had a reflective mylar "bird tape" streamer if it actually worked...

Obviously the inertia of accelerating the nosecone and recover harness, was more the radial capacity of the cardboard tube.

View attachment 592731

After I pulled it out.
View attachment 592732

Going to try it again with a wrap of vinyl around the top inch or two of the tube for support. (I had a 12 pack of the Estes Generic E2X...)

Wow, I flew those on the old Aerotech Single use 18mm D motors; always a champ on those ; and many others I would declare on the launch card "Yet Another Disposable Rocket"

 

[Art Upton]

I've posted this before... but still interesting:

This happened to my attempt to push and Estes Generic E2X as hard as I possibly could...(D20-8). the tube split allowing the nose to collapse back into it. Obviously the ejection charge didn't get it pushed back out. Landed about 300ft away. It didn't get too high with all the extra drag from this on the front end....that's the only reason I was able to track it on a perfectly cloudless day with sun at a good angle. Had a reflective mylar "bird tape" streamer if it actually worked...

Obviously the inertia of accelerating the nosecone and recover harness, was more the radial capacity of the cardboard tube.

View attachment 592731

After I pulled it out.
View attachment 592732

Going to try it again with a wrap of vinyl around the top inch or two of the tube for support. (I had a 12 pack of the Estes Generic E2X...)

Try putting a automotive pinstripe from your local auto store on the top of the body tube. It looks like that tube is not the best compared to my E2X rockets I bought at the "Lobby"

 

[BEC]

Wow, I flew those on the old Aerotech Single use 18mm D motors; always a champ on those ; and many others I would declare on the launch card "Yet Another Disposable Rocket"

Yeah, I think I’ve flown my DRM at least once on a D10W motor. I miss those and the D21s.

 

[Tractionengines]

Are you sure we’re not just looking at a wimpy/non-existent ejection charge-caused failure here?

I thought I heard a pop, so it was somewhat energetic. The chute and cord by the motor was charred/burnt, even tho what is in that photo is not. Could have been "slow" or weak.

Try putting a automotive pinstripe from your local auto store on the top of the body tube. It looks like that tube is not the best compared to my E2X rockets I bought at the "Lobby"

It does seem like the fit is a little loose on some of the tubes in the bulk pack. Also the step at the shoulder is not "sharp" but has a slight chamfer in the molding. Add to that, that I added a little nose weight to optimize overall weight...etc. It all probably combined into thel failure.

Both of the above are why I will try this again later this year, IF we get ideal conditions... Reinforce the tube end just a little. File the step on the nosecone to a sharper edge. Check the BP charge. Then "send it"...

 

[Art Upton]

Even on my 7.5" L3 rocket I reinforced the upper edge of the body tube; it was a LOC Kraft body tube not fiber glass.

Now many times I simply add some pin stripe or other monocoat decal like thing on all body tubes to prevent stuff from "happening" up there.

 

[4regt4]

I don’t think I’ve ever put a D20 in a Generic E2X but I‘ve put them in other BT-50 models. Are you sure we’re not just looking at a wimpy/non-existent ejection charge-caused failure here? The Q-Jets have been a little erratic and recent ones have weaker charges in the -6 and -8s than in the -4s, though I’d expect even that charge would be good enough to get that blow-molded nose cone off the top of a Generic E2X.

This will give me something to try at Sod Blaster V over Labor Day weekend - try to kill a Generic E2X like this.

Almost hate to say this, but I've been pulling the plug on all AT single use motors and measuring the BP. Quite a few are deficient. Especially the E20s and E30s. But I've had to supplement Qjets as well.

Hans.

 

[86mustang408w]

Yes.

 

[BEC]

Almost hate to say this, but I've been pulling the plug on all AT single use motors and measuring the BP. Quite a few are deficient. Especially the E20s and E30s. But I've had to supplement Qjets as well.

Hans.

I took to taking half the powder out of the early Q-Jets that had over-enthusiastic ejection charges for BT-20 and BT-50-sized models.

I can see, just given the huge volume difference between, say, a Viking and a Big Bertha (18mm) or Goblin and Mean Machine (24mm), why sizing an ejection charge "properly" is a bit of a challenge for both Estes and Aerotech/Quest.

 

[SolarYellow]

I can see, just given the huge volume difference between, say, a Viking and a Big Bertha (18mm) or Goblin and Mean Machine (24mm), why sizing an ejection charge "properly" is a bit of a challenge for both Estes and Aerotech/Quest.

If you want it done right, you have to do it yourself.

 

[4regt4]

I took to taking half the powder out of the early Q-Jets that had over-enthusiastic ejection charges for BT-20 and BT-50-sized models.

I can see, just given the huge volume difference between, say, a Viking and a Big Bertha (18mm) or Goblin and Mean Machine (24mm), why sizing an ejection charge "properly" is a bit of a challenge for both Estes and Aerotech/Quest.

What I am going off of is a chart that someone here provided showing what is supposedly the nominal BP content of AT motors. In particular, the 24mm ones - both AT Enerjet and Qjet - are supposed to have 0.7g. Most are closer to 0.6g, some down around 0.55g. So I boost them back up to 0.7g, maybe a bit higher if it's going to fly a bigger body tube.

The 18mm Qjets are supposed to have 0.5g. I routinely bump them up some when I'm flying in a bigger rocket using an adapter.

Hans.

 

[Tractionengines]

If you want it done right, you have to do it yourself.

At least with Q-Jets (and other Aerotech motors) ; you can measure and do it yourself. With manufacturers blanket approval, so its allowed by safety code.

There is no way to adjust the BP motors. At least no approved or simple way.

 

[Chris in Idaho]

Thanks everyone for the discussion. The Boys have their boosters built and if it's not windy we'll be painting tonight. I don't know if they're more excited or me!

 

[86mustang408w]

I'm putting a E12-6 in a Crossfire ISX, yours can handle it! Along with a Baby Bertha and the same motor with one already built.

 

[John Taylor]

My two sons age 6 and 9 have both just chosen the Der Red Max for their first rocket. It's entirely possible that these rockets may see higher performance engines such as the Quest D16 sometime during their lives. Can the DRM with its cardstock centering rings handle the 22.3N peak thrust?

Should we build in some sort of upgrade? Perhaps some longitudinal gussets between the MMT and BT? Or would these plywood centering rings from Apogee work?

Thanks very much!

Mine is plywood upgraded and 29mm G64's are what I fly it on
Delay time determined by weight and diameter of the rocket.
Try Thrustcurve.org.

 

[John Taylor]

Yeah, I think I’ve flown my DRM at least once on a D10W motor. I miss those and the D21s.

Dont forget about Aerotech 18mm RMS D13 White Lightning propellent. A full D motor at 20ns. More than a 24mm Estes D engine at 17ns.

 

[John Taylor]

I'm putting a E12-6 in a Crossfire ISX, yours can handle it! Along with a Baby Bertha and the same motor with one already built.

Is an E12 29mm?

 

[86mustang408w]

Is an E12 29mm?

No its 24mm. But Baby Bertha is 29mm.