Minimum mass H rocket?

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mollwollfumble

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Hi, I want to build an H rocket for level 1 certification that is as light in weight as is safe.

Going the Cesaroni route.

What total rocket mass (or mass range) should I be aiming for?
 
That would depend on what your goal is: max speed or max altitude? Speed is as light as possible but altitude requires your find the optimal weight which generally heavier than a speed rocket. A simulation program can provide you with those number by playing around with various weights and running the sim to dial in the right weight. The sims factor the right motors, too. Just requires a lot of sim runs ;)
 
Just saying, you could look at a 29m tube and nose cone with some FG fins, and shove an H410 in it. It will break Mach 1 in under a 6th of a second.
 
One of the estes pro series 2 kits would work well.


Sent from my iPhone using Rocketry Forum
 
You could, I suppose, make a 29mm flying case, essentially a downscale of Carvac's N-5800 attempt--have someone like Landru make a fin can to bond to a 29mm case, then figure out a hardpoint or some other attachment for airframe and nosecone. Your electronics might be limited due to size, but the Raven 3 would work --there's even a 29mm Featherweight av-bay.


If you're looking for a kit on which to L1, there are a great many options out there. You might do well to look at various manufacturer's websites, and make note of designs which appeal to you...



Later!

--Coop
 
Area66 said:
Estes ??, Estes are toy rockets made in China, why not a Wildman Blackhawk made in USA ?
Click to expand...

The Blackhawk series are minimum diameter and made out of carbonate which is not light I have a blackhawk38 and it weighs in at about 4lbs. The Estes pro series 2 rockets are light, cheap and are great for L1 attempts that can also be flown on mid-power motors as well.


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A Blackhawk 29, with an H410 or H399 should give you the kind of results you're looking for, you may never see it again without a tracker, but it'll get up and go!

Nate
 
Is it just me because I thought he was asking for a light weight rocket not a minimum diameter rocket?


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conman13 said:
The Blackhawk series are minimum diameter and made out of carbonate which is not light I have a blackhawk38 and it weighs in at about 4lbs. The Estes pro series 2 rockets are light, cheap and are great for L1 attempts that can also be flown on mid-power motors as well.
Click to expand...

you means Carbonite , a Blackhawk 29 is made of Carbon Fiber and weight 11 ounces.
 
conman13 said:
Is it just me because I thought he was asking for a light weight rocket not a minimum diameter rocket?


Sent from my iPhone using Rocketry Forum
Click to expand...
Good point, he never did say anything about min. diameter, but "minimum mass" would probably end up being minimum diameter, or a "flying motor case" type thing.
For a lightweight MPR/HPR rocket, an Estes PSII rocket would work well, but they aren't built for performance.

Nate
 
The lightest rocket that will not go too high will be a saucer or a related design. For example I have a cone-fin rocket that is 5.5" dia. and weighs 5 oz. Simulations show that it would reach 999 feet on a G80T if I added 1 pound of weight to it, although without ballast it only reaches maybe 700'. The old G25 would take it to about 1350 as-is. The real motor limit is how much air pressure the cone fin can take, since most of the thrust ends up going into that drag.
 
mollwollfumble said:
Hi, I want to build an H rocket for level 1 certification that is as light in weight as is safe.

Going the Cesaroni route.

What total rocket mass (or mass range) should I be aiming for?
Click to expand...

I'm not going for maximum speed or maximum height for this rocket. I'm going for L1 certification, which means aiming for best chance of recovery. Trying for average altitude.

Definitely not a kit rocket. Yes, I'm going minimum diameter, 29mm with a 3-grain H motor.

Are you saying that my home-made L1 certification rocket should have the same mass as a kit rocket?
 
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Best chance of recovery is not a minimum diameter 29mm minimum mass rocket. A rocket like that will obtain obscene altitudes on relatively small motors very very quickly which means out of sight PDQ. I am not telling you what to fly but if you are not flying electronics or with the aid of a tracker, a 29mm may not be a good direction.
 
mollwollfumble said:
I'm not going for maximum speed or maximum height for this rocket. I'm going for L1 certification, which means aiming for best chance of recovery. Trying for average altitude.

Definitely not a kit rocket. Yes, I'm going minimum diameter, 29mm with a 3-grain H motor.

Are you saying that my home-made L1 certification rocket should have the same mass as a kit rocket?
Click to expand...


I did my Lev 1 with a G-force of 50 onces a H90 for an altitude of 1000 feet, that's a great altitude for certification, the G-Force is a 4" rocket, so if you scratch build a 4" and the weight is about the same it give you an idea of the high it will go .
 
A CTI 29mm H will put a 3" diameter Leviathan up high enough (2000'+) that it's on the edge of what most people can see. For a minimum diameter rocket you're going to be way out of sight. Good luck!
 
So here is an near optimal mass 29mm rocket on an H90CL-12.
1. The longest stock delay is short by over a second.
2. The altitude sims to just over 6K ft.
3. The max speed is over 820 mph.
4. The max acceleration is over 42 Gs.

This is NOT the best idea for a L1 attempt.

I would suggest a scratch built 3" or 4" rocket similar to a Mad Cow Cowabunga. Easy to see, etc., etc.

29mm-mm.jpg
 
Flying a 29MD for your L1 will no doubt be more difficult, but don't let that discourage you if that's what you really want to do.

Alex
 
Area66 said:
Estes ??, Estes are toy rockets made in China, why not a Wildman Blackhawk made in USA ?
Click to expand...

They all are toy rockets when you get down to it. No need to snub Estes. They are no better or worse than anything else - it goes up and comes back down.

That said, I will agree that the blackhawk 29 is likely the easiest way to get a very light and durable rocket from a kit.
 
mollwollfumble said:
I'm not going for maximum speed or maximum height for this rocket. I'm going for L1 certification, which means aiming for best chance of recovery. Trying for average altitude.

Definitely not a kit rocket. Yes, I'm going minimum diameter, 29mm with a 3-grain H motor.

QUOTE]
While there is absolutely nothing wrong with the goal of a lightweight rocket, nor a minimum diameter rocket, I am curious:

If you aren't going for maximum speed

and you aren't going for maximum altitude

then why are you concerned that it must be lightweight and minimum diameter?

It does seem that if your number one goal is a successful L1 flight which requires recovery, your desire for lightweight and minimum diameter are slightly at odds with that goal. Perhaps you have something planned for the rocket AFTER the L1 attempt?

I'm thinking your combined goals (successful, recoverable, average altitude, lightweight, minimum diameter) would be do-able with a very draggy rocket, perhaps lots of finnage.
Click to expand...
 
jsargevt said:
They all are toy rockets when you get down to it. No need to snub Estes. They are no better or worse than anything else - it goes up and comes back down.

That said, I will agree that the blackhawk 29 is likely the easiest way to get a very light and durable rocket from a kit.
Click to expand...

I will not pass too much time to argue on this, especially if you can appreciate the quality difference between Estes tubing and other HPR manufacturer's kits, this is the HPR section of the forum.
 
Certifying on an Estes PSII is certainly a proven option, even if not a fullrange L1 flyer, compared to what he proposes.

Perhaps you have something planned for the rocket AFTER the L1 attempt?
Click to expand...

Well it should fly great on E9s, but suggest doing it before, as it there may be no after. I guess he could do it to fly what he wants without concern for actually getting certified, but don't know if an RSO would allow it.
 
mollwollfumble said:
I'm not going for maximum speed or maximum height for this rocket. I'm going for L1 certification, which means aiming for best chance of recovery. Trying for average altitude.

Definitely not a kit rocket. Yes, I'm going minimum diameter, 29mm with a 3-grain H motor.

Are you saying that my home-made L1 certification rocket should have the same mass as a kit rocket?
Click to expand...
If you plan on using a minimum diameter rocket, you are going to have a near maximum altitude flight at near maximum speed. Any small 29 mm minimum diameter rocket is likely to go 6000+' on an H! You can't see a 29 mm rocket at 6,000', and if the winds were at the high power limit of 20 mph, the rocket will drift 2' sideways for every foot of apogee so a rocket going to 6,000' could drift more than 2 miles from the launch pad! Good luck finding it with a tracker.

IMO the primary purpose of a cert flight should be get the certification. The best chance of recovery for any rocket is to minimize the apogee height so you can see the rocket through all phases of the flight. I use a ~4 pound 4" 4FNC rocket with a Pro38 H400 motor. A high thrust, short burn motor jumps of the pad and negates the weather cocking at higher wind velocities. It also generates a lot of drag so the apogee is lower than a lower thrust, longer burning motor. Both factors improve your chance of recovery. My L1 cert flight took 9 seconds to reach a 1300' apogee and about 65 second to come down. The wind was 10 mph gusting to 15 mph but the rocket went straight up due to a high T/W ~ 21. The rocket landed ~1,300' from the pad.

A 2 pound 29 mm minimum diameter on an H will apogee from 2,400' to over 5.500' depending on the motor. Under the same conditions as my cert flight, the drift would range from 2,400' to over 5,500'. It would have been much harder to track and recover a 3x smaller rocket at 2x to 4x the recovery distance of my 4" cert rocket.

Bob
 
I have to answer the original questions with a question of my own. If you cannot answer the questions you asked, are you truely prepared for L1 certification? I am concerned that you don't understand the basics necessary for building and flying L1 rockets. There isn't a magic minimum mass or size. There are parameters of flight that must be fulfilled or your rocket will fly in cartwheels, you will not get certified, and someone may get injured or killed.

As has been said many times in the various threads on the subject; get your certification, then expand in the direction of your choosing. At the same time, build what you will fly. If you like minimum diameter, go for it, but be prepared for long walks to recover the rocket, even with electronics, if you can recover it at all. Keep in mind that no recovery also means no certification.

Maybe I am being a judgemental butthead again. I do not know your history with rockets. I have browsed through your discussion on building a many staged rocket, but I still have concerns.
 
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> If you aren't going for maximum speed, and you aren't going for maximum altitude, then why are you concerned that it must be lightweight and minimum diameter?

Practice. I want to run maximum altitude minimum diameter multistage rockets in future, but the L1 test won't allow me to multistage, eg. won't allow me to run 2*G motors instead of 1*H.

> If you plan on using a minimum diameter rocket, you are going to have a near maximum altitude flight at near maximum speed. Any small 29 mm minimum diameter rocket is likely to go 6000+' on an H! You can't see a 29 mm rocket at 6,000', and if the winds were at the high power limit of 20 mph, the rocket will drift 2' sideways for every foot of apogee so a rocket going to 6,000' could drift more than 2 miles from the launch pad! Good luck finding it with a tracker. A 2 pound 29 mm minimum diameter on an H will apogee from 2,400' to over 5,500' depending on the motor.

I had planned on using a very low thrust H, an H54, to keep the altitude down, as well as the inevitable excruciatingly bad drag coefficient of this first high power attempt. But when I got to the launch site the winds were near the high power limit and I had a very large parachute - so I would have had a lot of trouble finding it (especially as this one had no tracker). Pre-launch altitude calculation 4,000'. I ended up not launching it and instead using it for a static test, parachute didn't deploy. So next step is to make another, hopefully better, for L1 certification.

> If you cannot answer the questions you asked, are you truely prepared for L1 certification?

As ready as anyone. So far I've fired off one each (not counting complete failures) of C, D, E, F and G. Next step is H. I have a PhD in engineering, but it's Civil Engineering not mechanical.

BIG QUESTION: The Cesaroni H54-10 motor took a full 6 seconds to start thrusting at maximum after the igniter finished firing. Any idea what caused the delay and is there anything I can do to to reduce that delay - I'm thinking it could have a deadly influence on timing of mutistaging.
 
mollwollfumble said:
> If you aren't going for maximum speed, and you aren't going for maximum altitude, then why are you concerned that it must be lightweight and minimum diameter?

Practice. I want to run maximum altitude minimum diameter multistage rockets in future, but the L1 test won't allow me to multistage, eg. won't allow me to run 2*G motors instead of 1*H.

> If you plan on using a minimum diameter rocket, you are going to have a near maximum altitude flight at near maximum speed. Any small 29 mm minimum diameter rocket is likely to go 6000+' on an H! You can't see a 29 mm rocket at 6,000', and if the winds were at the high power limit of 20 mph, the rocket will drift 2' sideways for every foot of apogee so a rocket going to 6,000' could drift more than 2 miles from the launch pad! Good luck finding it with a tracker. A 2 pound 29 mm minimum diameter on an H will apogee from 2,400' to over 5,500' depending on the motor.

I had planned on using a very low thrust H, an H54, to keep the altitude down, as well as the inevitable excruciatingly bad drag coefficient of this first high power attempt. But when I got to the launch site the winds were near the high power limit and I had a very large parachute - so I would have had a lot of trouble finding it (especially as this one had no tracker). Pre-launch altitude calculation 4,000'. I ended up not launching it and instead using it for a static test, parachute didn't deploy. So next step is to make another, hopefully better, for L1 certification.

> If you cannot answer the questions you asked, are you truely prepared for L1 certification?

As ready as anyone. So far I've fired off one each (not counting complete failures) of C, D, E, F and G. Next step is H. I have a PhD in engineering, but it's Civil Engineering not mechanical.

BIG QUESTION: The Cesaroni H54-10 motor took a full 6 seconds to start thrusting at maximum after the igniter finished firing. Any idea what caused the delay and is there anything I can do to to reduce that delay - I'm thinking it could have a deadly influence on timing of mutistaging.
Click to expand...

Low thrust does not keep altitude down; it in fact often increases the altitude.

Where did you find out the 6 second delay for the H54?
 
mollwollfumble said:
>
BIG QUESTION: The Cesaroni H54-10 motor took a full 6 seconds to start thrusting at maximum after the igniter finished firing. Any idea what caused the delay and is there anything I can do to to reduce that delay - I'm thinking it could have a deadly influence on timing of mutistaging.
Click to expand...

I'm curious why you think this. Any delay (either ignition or post-burn) has almost no relevance to multistaging with composite motors.
 

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