Der Red Max handle D16?

[Chris in Idaho]

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!

 

[rharshberger]

Easily...the question is how high is it going to go and will you get it back.

Adding gussets or plywood CR's is optional (I would recommend ordering the CR's from either Balsa Machining Service or eRockets...lower prices).

 

[bad_idea]

Easy enough to test. Take an expended 29mm motor and tape a thrust ring to it fairly far down the motor, such that it holds securely in a vertical position without wobbling yet protrudes far enough you can work with it. Glue a level platform of some kind to the end of the motor. Remove the nose cone and place the rocket nose down on a flat surface. Then add enough weight to the platform to equal 22.3N of force (including the weight of the platform and the dummy motor).

In standard Earth gravity (varies slightly by location), 22.3N is produced by the mass of 2.35 kg.

Edit to add: I have no doubt the standard rings will work. I have flown my crashed, rebuilt, and bashed DBRM on the I200 on stock cardstock rings, albeit with epoxied fins. (I had actually forgotten it had the stock rings when I started this post.)

Never mind. I thought you were asking about Der Big Red Max. My apologies.

 

[ljwilley]

Meh, that's nothing. I'm going to try to make a der red max w/ a 29mm motor mount and see how it goes on an F67!

 

[bad_idea]

The weak point of the DBRM is the fins, not the rings. The fins are weak from being 1) balsa on a heavy rocket, 2) two-piece balsa on a heavy rocket, and 3) large, protruding, rear-swept two-piece balsa on a heavy rocket.

My bash/rebuild has the stock fins cut down to reasonable size and glassed on both sides. (No tip-to-tip though.) I wouldn't fly the stock fins on an I motor. But the rings will hold for an I (with epoxied fins at least), and for a D16 or F67, the fins will too. Before the crash and rebuild, I flew the stock fins on the F67W and the G74W. The only damage was a smushed fin tip due to a hard landing.

Never mind. Thought this was in Mid-Power and was talking about DBRM, not the standard Red Max. Sorry.

 

[ljwilley]

But you are right, it is the fins. I made a scratch build mega der red max after it was OOP and made sure I used plywood fins and centering rings.

 

[Chris in Idaho]

Meh, that's nothing. I'm going to try to make a der red max w/ a 29mm motor mount and see how it goes on an F67!

Now we're talking!

 

[ljwilley]

Of course I will have to carbon fiber the fins. (so that it will be strong and look good!!)

 

[techrat]

I flew a standard Big Bertha on a Quest D20. It flew, the problem was I never saw the rocket again. The Body tube and fins were able to take the acceleration, but the problem was the damn thing was so light I'd swear it's still in orbit right now.

 

[ljwilley]

In about a week I am also going to launch a a minimum dia. 18mm rocket using some spare Estes parts on a d20- I don't plan on getting that one back!

 

[bad_idea]

In about a week I am also going to launch a a minimum dia. 18mm rocket using some spare Estes parts on a d20- I don't plan on getting that one back!

I've found that long (i.e., 10-15m), reflective streamers - either mylar or bird-scare ribbon - are pretty easy to get a bearing on when launched down-sun. Maybe not with an H13, but I've flown 35mm Quest-based rockets to 2k or more on F motors and gotten them back.

 

[Tractionengines]

Just for reference here is a STOCK Goblin on a D22-4.


Here is Flight Data from the FlightSketch Mini. Pulled about 21Gs off the pad and went to 896ft.
https://flightsketch.com/flights/3717/
It did tear 1 of the 2 streamers off at ejection. So it came down kind of fast, but into tall grass so it flew again a few minutes later. Fun disappearing act, in calm weather.

 

[Tractionengines]

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.

My kids are 11, 8, 5 at the moment, and I look at this as learning to "fly-the-field" and the conditions. (Something I still need to learn sometimes.) Letting them pick a delay that's way off, or a motor like this is learning. (As long as I and/or the RSO/LCO feel it's safe. Who's around, how many people are around, which way is the wind going, how dry is the grass, etc.) I can tell them lots, but watching your rocket drift into a tree, disappear never to be seen again, or pop the chute 100ft above the ground, etc.; sticks in the memory.

HAVE FUN.

 

[Chris in Idaho]

Thanks everyone, just the kind of helpful discussion I was hoping for. Just to be clear, I'm talking about the standard Der Red Max with the 41mm body tube and 18mm motors.

The bigger body tube knocks the performance down vs the typical 24mm rockets like an Alpha. Estes says an Alpha III will go 1,150ft on a C6, but they say a DRM will only go 600ft on the same motor. In fact Estes doesn't even recommend flying it on A engines, just B4, B6 or C6.

So the idea of the Quest D16 probably isn't as much of an "out of sight" proposition as it would be on a skinnier rocket.

I like that they chose the DRM in part because of the lower performance and being easier to see in the air will make it very forgiving for the learning curve that's in store. The other reason is for ease of chute packing and general handling with the bigger tube.

However, being that it only goes half as high as everyone else's rocket on the same C6-5, and those D16s will be out there taunting the boys, I think it prudent to build it to handle some abuse.

 

[Chris in Idaho]

I'm no rocket scientist but 18mm to 41mm is a wide span for the centering ring to fill, and having just two of them made from card stock with no FTW fins or anything else to support the MMT doesn't strike me as super robust.
But, based on the comments here, we'll probably keep them stock.

 

[techrat]

Another advantage of DRM is that those wide, long, square fins make hella drag. Very likely that's why you can't fly on an A8-3. I had the same problem with Big Bertha. An A8-3 was not enough to do more than clear the launch rod, and the rocket fell back to earth. B6-4 was the minimum for a decent flight. And like I said, the D20 made it go poof, never to be seen again although it likely survived the flight and is still stuck in a tree someplace. If your field is wider than mine, a D16 is likely recoverable.

 

[86mustang408w]

It could take a 29 mm if you did it right. I have E9's in a Baby Bertha. But the motor kit and build away!!

 

[n3tjm]

If you built it with wood glue, not glue all or school glue, and put some nice fillets on the joints it will be fine.

 

[Tom Flint]

I've flown mine on a D16 and even a D20 with stock centering rings and it worked just fine.

 

[Chris in Idaho]

Sounds great, stock it is!

 

[Bill S]

If you use wood glue, probably okay. I used to fly plenty of low powered rockets with Q-Jets, up to D20s, with no issues with the stock Estes mounts coming loose, etc. But, but you have a significant chance of that D16 either blowing up or your rocket shooting off in an unexpected direction - the clay in the nozzles (at least in less recent motors) was wonky and prone to problems. I had about 1/3 of my Q-Jet flights end up in an incident, whether that be an actual CATO, burnthough the side of the motor, premature ejection of the parachute while still under boost, etc. Which is why I gave up on them.

 

[techrat]

I had about 1/3 of my Q-Jet flights end up in an incident, whether that be an actual CATO, burnthough the side of the motor, premature ejection of the parachute while still under boost, etc. Which is why I gave up on them.

I think the latest iteration of the Qjet motors are switching the clay nozzle for something more robust so I'd say that Aerotech has heard the consumer complaints and is (slowly) doing something about it.

 

[4regt4]

Just for reference:

I got 430ft on a C18-4 in a DRM, and 758 on a D20-4. Other than my usual shock cord mods, it was built with the stock components.

Hans.

 

[allensmith]

That rocket flies great on both C5-3 and C6-5 motors. I think the construction can handle the Quest D motors, but I've had a incident with a D20-4 where the ejection didn't fire and a great ESAM-58 flight turned into a lawn dart. YMMV.

 

[SolarYellow]

The D16 is only about 25% more N-sec than a C6-5:

Total Impulse: 12.4 N-sec

As stated above, the CRs will be fine. Use wood glue and make sure they are reasonably well filleted.

The BT-60 and big fins will keep it easily in sight, and the high thrust will get it off the rod for a nice, vertical flight.

 

[PDawg]

In about a week I am also going to launch a a minimum dia. 18mm rocket using some spare Estes parts on a d20- I don't plan on getting that one back!

Use a reflective streamer and your chances go up significantly. I've launched my Minimum Diameter F-15-8 and E-12-6 rockets and got them back several times each, each one landed less than 50 feet away but eventually they get lost since my field isn't that big.

 

[Tractionengines]

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.



After I pulled it out.


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...)

 

[BABAR]

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!

Little late to the party.

It can be a real discouragement for a kid (or adult/pseudo-kid) to lose a rocket that she or he has personally picked out, spent time not just building but finishing it to the best of her or his abilities (even if to others it may look a bit rough.)

Rather than beef up an existing rocket, might be better to buy another set of rockets that you build with intent to fly high. Things that can help are streamer recovery and forward swept fins (the latter so the rocket is more impact the ground an a single use motor casing than a fin.) the kid can decide how much “finish work” to do on a rocket that may have a rough landing or end up in a tree. Buying a rocket DESIGNED for the motor you want to use/altitude you aspiring for is also a plus.

That said, I am of the opinion that you should never intentionally outfly the field, I.e. every rocket should be launched with realistic intent that it will have a high probability of returning to earth INSIDE a safe zone.

Sometimes meconium happens, but I’ve seen some rocket videos where people are launching near busy public roadways or other areas where a rocket landing (even under a good chute) might cause quite a brouhaha or worse. While we may BUILD models that look like Sidewinders or Phoenix missiles, I don’t believe our rockets should ever be “fire and forget” projectiles in practice.

Maybe I am getting old. I like staging, but i like the flight to stay in visual range. For low power, I don’t see (pun intended) much point in going over 500 feet. I DO prefer the rocket clear the rod before staging, though (no more A8-0s for me !). It was retrospectively amusing for my Dad and I in the late 1970s to look for 10 minutes for the booster (we easily tracked and recovered the SUSTAINER, we were confounded as we never SAW the staging event), only to see the booster sitting nice and perky on the pad.

Stay safe and have fun!

 

[BEC]

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!

No problem. Just build it carefully (with stock parts) and fly it. It will be fine.

I haven’t done much altimeter flying with the DRM, so I can’t really predict the altitude. My almost-stock Big Bertha went to just under 800 feet the last time I flew it on a D16 (https://flightsketch.com/flights/3391/). I’d expect a DRM, being a little smaller and lighter, might get to 900 or a bit more. That will be high enough that the drift on that bigger-than-needed DRM ‘chute with the neat design might drift a good distance. Put a 12 incher in there, or a streamer as suggested above, to cut down on that.

added: I didn’t see @4regt4’s post as I was skimming this thread. Maybe I’m over optimistic about the DRM’s performance potential.

 

[BEC]

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...)

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.