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Big Daddy Lawn Darts... Show of Hands Please.

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Spitfire222

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Not to derail the thread, but that is indeed a very cool paint job. A very good idea, with an excellent execution. Glad it survived to keep on flying!
 

JRAJ

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I'm starting to wonder how many of these lawn darts could just be attributed to using a D12-5 which may be too long of a delay?
I also wonder how many ejection charges happen upon impact with the D12-5's - when I watched my video back, the impact took place approx. 6 to 6 1/2 seconds after motor burnout.
My ejection happened just in the nick of time to save the body tube.
I've read through a few posts in the thread where others claim to have used a D12-5.
A D12-3 might more suitable for low altitude flights. Both are listed as options on the packaging. Perhaps they should just quit suggesting D12-5's?
Doesn't have enough thrust to reach the altitude needed for a 5 second delay?
 

Nytrunner

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Other considerations:
They are tested in hmm colorado where air is thin
People overbuild
 

JRAJ

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They are tested in hmm colorado where air is thin
People overbuild
Good point.
Here in N. Texas at about 550' elevation. My modified nose rocket came in 1oz over normal weight.
 

shreadvector

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I'm starting to wonder how many of these lawn darts could just be attributed to using a D12-5 which may be too long of a delay?
I also wonder how many ejection charges happen upon impact with the D12-5's - when I watched my video back, the impact took place approx. 6 to 6 1/2 seconds after motor burnout.
My ejection happened just in the nick of time to save the body tube.
I've read through a few posts in the thread where others claim to have used a D12-5.
A D12-3 might more suitable for low altitude flights. Both are listed as options on the packaging. Perhaps they should just quit suggesting D12-5's?
Doesn't have enough thrust to reach the altitude needed for a 5 second delay?
That is my theory.

People use too long of a delay all the time. Sometimes it is because the manufacturer recommends that motor with too long a delay. Sometimes it’s because the rod is angled and you need to choose a shorter delay when angled. Sometimes the Rocket was built way too heavy.

Sometimes it’s all of the above.
 

rharshberger

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Adding any noseweight to a Big Daddies nosecone is going to change the length of required delay. So it could easily be too long on a 5 sec delay.
 

Super_Dave_47

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Had one lawn dart yesterday. This rocket had flown about 5-6 times before and was a trooper. Has landed on concrete no damage. I think this incident was my fault though. I first flew it on a D12-3 and it was perfect. Came down 100 feet from the pad, perfect. I had loaded that rocket at home, i.e. did the wadding and folded the chute. Second launch I loaded on the field. Wind was picking up so I went with D12-5, which I wasn't very confident of since I knew it would be coming down at ejection. But I did it anyway, as I was having good luck so far so I figured the gods were with me. Also think I put TOO MUCH wadding the second time, and I can never fold a chute as well on the field as at home. Nose cone never came off and it buried itself two inches in the grass. Nose cone is fine, fins and motor mount fine. Tube a little crimped but to be honest I think with just a couple rounds of masking take at the top of the tube it would be perfectly flyable. Ugly as sin, but flyable. Plastic chute was a total loss. I may try to launch as-is, and if it doesn't go will do some major surgery -- I am thinking of making slightly longer so I can add a baffle, and ditch the Estes shock cord for kevlar.

IMG_3360.jpg
IMG_3359.jpg
 

Spitfire222

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Not to derail this thread, but I didn't want to start a new thread for a quick question. Neither of the two flights I have on my Big Daddy I would consider a success.
Flight 1: Estes E12-4, rocket launched and promptly curved over and flew horizontally until ejection. There was a bit of wind; not calm, but not super windy either.
Flight 2: Aerotech E20-4. Rocket immediately skywrites/cartwheels once clear of the 5' 3/16" rod. Windy day, but the flight was so erratic I doubt that even had an effect.

Disclaimer, this rocket is modified with plywood centering rings, reinforced fins, etc. so it weighs more than it should. I've learned my lesson, but I would like to fix this rocket so it flies better. Based on the above flight descriptions, am I correct in thinking that it needs nose-weight?

I know that short-coupled rockets like the Big Daddy get a lot of their stability from base drag and that the usual 1 cal stability margin is not necessarily applicable here, so I just wanted a bit of guidance to tame this one. Thanks!
 

o1d_dude

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Not to derail this thread, but I didn't want to start a new thread for a quick question. Neither of the two flights I have on my Big Daddy I would consider a success.
Flight 1: Estes E12-4, rocket launched and promptly curved over and flew horizontally until ejection. There was a bit of wind; not calm, but not super windy either.
Flight 2: Aerotech E20-4. Rocket immediately skywrites/cartwheels once clear of the 5' 3/16" rod. Windy day, but the flight was so erratic I doubt that even had an effect.

Disclaimer, this rocket is modified with plywood centering rings, reinforced fins, etc. so it weighs more than it should. I've learned my lesson, but I would like to fix this rocket so it flies better. Based on the above flight descriptions, am I correct in thinking that it needs nose-weight?

I know that short-coupled rockets like the Big Daddy get a lot of their stability from base drag and that the usual 1 cal stability margin is not necessarily applicable here, so I just wanted a bit of guidance to tame this one. Thanks!
If you buy an upgrade kit for the Big Daddy, it usually comes with a small bag of lead shot.

The best kit I know of for the Big Daddy is the one sold by Rocketry Works in Tucson. I was very pleased with their kit: fins, c-rings, 29mm motor tube, lead shot.

Disclaimer: I have not yet built the upgraded kit so no flight report yet.
 

Super_Dave_47

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I flew my rocketry works 29mm upgrade last week at a club launch. On an F42-8. I was concerned about how heavy it felt in my hand with the lead shot in the nose, even though it weighed out correctly. Everything went fine, but I think the nose drag separated before the ejection charge went off. Next time I might use two tiny slivers of tape on the nose to prevent that from happening.
 

Long_Gone

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Yea mine went in this year and " it was my fault"! I did not want it to go real high in the back field of mine and checked Open Rocket how a C5-3 would do and it looked doable, so I gave it a shot. Well it flew nice and straight up and down! After it stuck 3" in the mud the ejection charge went off as expected and deployed the chute. I went back to my OR file and missed the fact the delay should have been 1.96 sec for that flight. Damn!!!!! So I fixed it and it is going up tomorrow on a RMS D15-4T. BTW the only damage was one fin had hit a branch of a tree coming in. I am looking at the data for C5-3 and it is not far off C11-3, last flight tomorrow if I get it back will be another try at C5-3. All the numbers should work out time to apogee is 3.81sec. and the 3 sec delay should be about right. I remember last time I tilted the rod fairly aggressive in to the wind, probably did not help. Tomorrow 90* no tilt!!
 

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Back_at_it

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Because I am getting tired of seeing theory of Big Daddy Nose Cone design issues I am going to post the statement from Steve Kristal on the NAR FB page:

Steve Kristal,
I just asked Matt Steele who designed the kit. He flew that same nosecone on North Coast kits for years prior to the Big Daddy, and then for the last 22 years on the Big Daddy. He also flies a 2.6" cone just like it on his current kits. Ejection failure has never been a bigger issue on that nosecone than any other. Estes is crazy about safety. If that particular nosecone was an issue it would have been dealt with many many years ago. The urban legend on TRF is just completely unsubstantiated. You can find threads on TRF where people talk about modifying the cone but you're not seeing reports of numerous lawn darts. You are also not seeing them on Ye Olde. You don't see them on 20 years of flight logs (currently406 of them) on RocketReviews. And you don't see reports here. The Big Daddy nosecone is no more prone to failure to eject than any other cone.
I have complete respect for those that design these things for a living and understanding that these are very knowledgeable people. I thank everyone of them for giving us products that we can go out and enjoy, so thank you.

Now for personal experience. I've owned and flown 3 Big Daddies with 3 more hanging on the wall. Clearly, I like the kit. The first was the early version with the 24mm D length mount. The second was also an early version but I extended the mount to fit E motors. The last one is built for 29mm with Basswood fins and a plywood upper centering ring.

I tend to over build so my stock BD is a couple ounces over the advertised weight. The first flight on the first BD was a D12-3 straight up on a calm day. The flight was perfect, and we heard the loud pop of the ejection at apogee. The nosecone pushed out but didn't pull the chute with it. The rocket fell sideways and landed in tall grass so no damage. Afterward the rocket was inspected, and nothing was wrong. The nose cone wasn't tight but also wasn't wobbling around loose either. My rule of thumb is that you should be able to pick the rocket up by the nosecone and the weight of the rocket should slowly separate the body from the nosecone. I chalked this up to a weak charge. I noted the date code on the motor and moved on.

A few weeks later we were out again, and I used another D12-3 that was purchased a couple days before we launched so different batch, different date code etc. Again, nice basically calm day. Rod straight up, perfect flight, loud pop of the ejection and the nose cone pushed out but no chute. This time it landed sideways in a grass field and broke a fin. I went to pick the body up and parachute fell out along with the shock cord so it wasn't tight.......

At this point I was scratching my head. I put the rocket away and let it sit for weeks while I got over it. Finally I was ready to work the problem and fix the rocket. Looking at it I didn't care for the shape of the nosecone. I also didn't like that it left very little room for the laundry but figured they did this to fill the volume in the body tube. I was wondering if the gas was escaping past that shoulder so I decided to do the old blow test. (minds out of the gutter guys). Insert the nosecone and blow into the motor tube to see if the cone would pop... Nope... It came out about 3/4 of the way and stopped. Mind you I was a healthy guy in my early thirties at this point, so I had pretty good lungs. I could feel the air escape past the shoulder. So obviously that was the issue.

Break out the power tools and epoxy and pretty soon we have a cut down nose cone with only about 1 inch of shoulder left. A bulkhead was inserted inside just above the shoulder lip and epoxied in place. I attached the laundry to a screw eye and called it done. A couple of weeks later we were back on the field for BD's third flight. Again, D12-3, Straight up, pop at apogee. This time we got a good ejection. I could see the nose cone stretch all 6ft the shock cord and pop back. The chute opened and it was a perfect fight. This rocket has been up literally dozens of times since then as well as its two siblings both with the same nose cone mod. with zero failure or even close calls.

You can preach all you want that the nose cone isn't an issue. I've experienced it firsthand twice, fixed the issue and never had an issue after that.
 
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Long_Gone

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Hmnnnn Todays flight may have issues. But I am positive it WILL work today. Going to launch right now.

LG~
 

Long_Gone

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Ok bad day of flying getting windy in PA and my Medium Power igniters will NOT ignite the engine all Aerotech RMS???? So I need to do something different. The Estes engines first time go's the modified Alpha III with an altimeter payload bay reached 116ft and 316ft A and B engines. No issues. So I darted the Daddy in the field out back on the C6-3 (so don't do that) but the chute came out at 10ft so it was all my fault. So I am getting some Estes D's and have at it.

LG~
 

Back_at_it

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Ok bad day of flying getting windy in PA and my Medium Power igniters will NOT ignite the engine all Aerotech RMS???? So I need to do something different. The Estes engines first time go's the modified Alpha III with an altimeter payload bay reached 116ft and 316ft A and B engines. No issues. So I darted the Daddy in the field out back on the C6-3 (so don't do that) but the chute came out at 10ft so it was all my fault. So I am getting some Estes D's and have at it.
LG~
Yeah, the C6 doesn't have the kick to really get it off the pad. Some say the C5-3 is better but I don't know if I'd trust it. I can tell you that I have seen a stock BD fly on a C11-3. This thing was dead stock and wasn't built heavy. It flew well but I wouldn't try it if you are like me an over build things.
 

Long_Gone

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I'm good live in the country but there are trees and they love airplanes, helicopters and Rockets. I fly them all here. I have been having soo much trouble with BD and the Aerotech igniters/RMS that I have ordered the Cherokee E and some D/E engines from Hobby lobby. The damn wind is terrible today had to stop all operations.

LG~
 

modeltrains

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Hmm, my Big Daddy has sat almost but not quite finished for several years and is therefore unflown.
Perhaps it may remain unflown.
🤔
 

Zbench

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I think you are on to the right track here, but maybe not for the reason you think.

I fool around with swaging bullets which involves a hydraulic press pushing lead and copper together in a hardened steel die. Even though the die is big, and the steel is strong, you can crack them if you don't know what you are doing.

The ejection charge in a rocket is not dissimilar from a hydraulic press system, main difference is the hydraulics in a rocket is powered by an explosion and the compression of air instead of an electric pump and hydraulic oil.

There is a formula that is used to describe this relationship. It is P=F/A, where P is the pressure inside the die, F is the force behind the tight fitting punch and A is the area of the punch. In our rocket case, the P, which is in pounds per square inch is the ejection charge pressure in the tube before the nose cone comes off, F is the force against the base of the nose cone and A is the area of the base of the nose cone. Since the ejection charge is set, say at 15 psi (or whatever reasonable number you want to use), we rearrange the formula to be F= P*A

Solving for the Big Daddy, the force on the nose cone would be 15(Pi*1.5^2) = 106 pounds

Solving for a rocket that is half that size, a 1.6" body tube would be 15(Pi*.8^2)= 30 pounds

As you can see, it takes much less force to exert the same pressure on the base of a nose cone that is half the size. Said simply, it's not the volume that matters, it's the cross sectional area the gases inside the rocket are pushing on. Since the ejection charge is fixed (at least in the case of Estes BP motors), any hiccup in the nose cone fit is going to be a bigger issue the larger the base of that nose cone becomes.

I personally believe the idea that a sticky nose cone getting pushed out to the ramp in the shoulder and then losing all the force of the escaping gas makes the most sense. Someone also mentioned that they seal the hole in the end of the nose cone. I don't know what effect this has, but my intial reaction in the area of the base of the nose cone would expand to the entire area inside the nose cone making the problem infintely worse. Sealing that up with a piece of epoxied balsa is not a bad approach.

Never had a lawn dart with my Leviathan. Then again I don't fly that with an E motor. Maybe the AT G-size motor has enough deploy charge to overcome the difficulties on the NC shape?
 

Joekeyo

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Here's what I have done to mitigate this potential problem. I have sanded down the ridges on the NC. The BT-NC fit is comparable to most rockets. Sealed the hole in the NC. I have replaced the motor tube with one that reaches to the base of the NC. I loosely stuffed a few sheets of wedding in that tube. I will pack the 'chute around the tube. The plan is that the ejection charge will work as designed because of the reduced volume. The wadding will protect the NC. It hasn't flown. I will report the flight.
 

modeltrains

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But is that really why you built it?
Good question ... given that my primary modeling is model trains and secondary modeling is miniatures for miniatures games, and I used to build stick and tissue airplanes before my health decline, it does appear that I build models which are meant to be used ...
 

CoAz2k

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I bought a BMS 3" school rocket (24mm) for my daughter.

I found the nose cone loose on hers. So I swapped it with the Big Daddy nose cone and both rockets are better for it.

The BMS nose cone is a bit longer, but fits the BD much better.

Available here.
 

Back_at_it

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I bought a BMS 3" school rocket (24mm) for my daughter.

I found the nose cone loose on hers. So I swapped it with the Big Daddy nose cone and both rockets are better for it.

The BMS nose cone is a bit longer, but fits the BD much better.

Available here.
BMS 3inch school rocket is a great product for not a lot of money. I don’t know if they advertise it but they also sell a 29mm version with stronger parts.
 

Senior Space Cadet

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Ok, you know who you are... Owners of once pristine Lawn Darts... Oops... Big Daddy Rockets that have lawn darted.

Who all has had one whistle in?

[EDIT] The following was posted from post #20:
I've probably only done a few dozen launches. I had one lawn dart. I, apparently, didn't glue the engine block well enough and the engine ended up inside the rocket. It still managed to get about a hundred feet up, but ejection didn't go so well.
 

crossfire

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Had one lawn dart yesterday. This rocket had flown about 5-6 times before and was a trooper. Has landed on concrete no damage. I think this incident was my fault though. I first flew it on a D12-3 and it was perfect. Came down 100 feet from the pad, perfect. I had loaded that rocket at home, i.e. did the wadding and folded the chute. Second launch I loaded on the field. Wind was picking up so I went with D12-5, which I wasn't very confident of since I knew it would be coming down at ejection. But I did it anyway, as I was having good luck so far so I figured the gods were with me. Also think I put TOO MUCH wadding the second time, and I can never fold a chute as well on the field as at home. Nose cone never came off and it buried itself two inches in the grass. Nose cone is fine, fins and motor mount fine. Tube a little crimped but to be honest I think with just a couple rounds of masking take at the top of the tube it would be perfectly flyable. Ugly as sin, but flyable. Plastic chute was a total loss. I may try to launch as-is, and if it doesn't go will do some major surgery -- I am thinking of making slightly longer so I can add a baffle, and ditch the Estes shock cord for kevlar.

View attachment 431026View attachment 431027
Go around tube with yellow colored duct tape. It will be stronger than new
 

Back_at_it

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I've probably only done a few dozen launches. I had one lawn dart. I, apparently, didn't glue the engine block well enough and the engine ended up inside the rocket. It still managed to get about a hundred feet up, but ejection didn't go so well.

I had a alien space probe lawn dart some yrs ago and it ripped the entire motor mount off. The paper centering rings failed
 
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