what gives with rocket weights?

[jayarrG7]

Estes says the Vagabond is 4.1 ozs.
My finished product weighs in at 6.1 oz. (no motor)
Does Estes weigh the parts only, or do they supply a weight amount that can actually be achieved.
What about other manufacturers? None of my builds come in at the weights I find on their sites.

 

[DAllen]

2 most probable reasons:

Too much...

1. Glue

and/or

2. Paint

:wink:

 

[Zeus-cat]

I suspect that the rockets built by Estes are put together by experts who use optimal amounts of glue and paint. My rockets are always heavier than the posted weights. I never worry about it.

 

[gpoehlein]

You could always jump over to YORF and ask John Boren, chief designer at Estes:

https://www.oldrocketforum.com/

He checks in there ever so often.

 

[Rex R]

I once put an estes kit on the scale (leaving out the packaging and instructions)...it weighed what it said in the catalog. I could have reduced the weight a little, I didn't remove the fins from the sheet or the chute from its' bag .
rex

 

[Wayco]

Estes says the Vagabond is 4.1 ozs.
My finished product weighs in at 6.1 oz. (no motor)
Does Estes weigh the parts only, or do they supply a weight amount that can actually be achieved.
What about other manufacturers? None of my builds come in at the weights I find on their sites.

The first Vagabond I built weighed in at 6 3/8 oz. I added a cold air baffle and paper skinned the fins, so I'm not surprised it's a little heavy. Using a 24/40 Aerotech reload makes that a non issue.
I think you might be onto something though, most of the advertized weights for the rockets I build are closer to the kit weight, not the built weight.

 

[powderburner]

If you are going to do any simulation or analysis at all, you need to weigh your own birds. And I don't mean to weigh them with the family bathroom scale, go spend the whopping $10 and get a 500 gm electronic scale (that's just over a pound capacity) at Harbor Freight or WMart or somewhere. You don't need to spend $50 or $100 or some crazy amount, just a basic scale.

It's well worth it.

If you can't find one locally, PM me and I will be happy to keep a watch on the local Harbor Freight adverts for the next time they have one on sale. (They seem to do this pretty often.) Shipping would add another $6.

 

[Marc_G]

I think I built a Wizard with thin dabs of CA once, no fillets, no paint. Weighed what the kit said it should. Sent it up on a B4-6 as I recall. It should be landing next week.

I don't think that things like fillets or paint are included as they are highly variable elements of the finished product.

Consider the kit weight to be the minimal achievable weight.

That all said, most of us over-build, myself definitely included. I certainly overpaint!

Marc

 

[GDJ]

Estes says the Vagabond is 4.1 ozs.
My finished product weighs in at 6.1 oz. (no motor)
Does Estes weigh the parts only, or do they supply a weight amount that can actually be achieved.
What about other manufacturers? None of my builds come in at the weights I find on their sites.

Hey, you did good! Mine weighed in at 6.9.
Epoxy paint is a tad heavy.

 

[JStarStar]

My guess is some of the older kit weights may actually have been the aggregate weight of the parts -- glue and paint not included.

It is certainly my experience that kits almost invariably turn out to be heavier when assembled than in the listed specs.

It would be interesting to ask John Boren or other designers if they have consistent standards for listing rocket weights: aggregate weight of parts, or optimal (minimal) weight if assembled by skilled modelers?

Of course they always include a disclaimer, "Assembled weights may vary depending on construction techniques."

 

[MarkII]

Estes says the Vagabond is 4.1 ozs.
My finished product weighs in at 6.1 oz. (no motor)

The first Vagabond I built weighed in at 6 3/8 oz. I added a cold air baffle and paper skinned the fins, so I'm not surprised it's a little heavy.

Hey, you did good! Mine weighed in at 6.9.
Epoxy paint is a tad heavy.

Geez! OK, let me start by saying that I don't own this kit, so maybe there are good reasons for these weights. But this thread started me thinking about what rockets I have that are in the same ballpark, weight-wise. The one that I came up with was this:

It is 43" long and 1.64" in diameter (lower section). It is 7.75" longer than the Estes Vagabond and the lower half is the same diameter as the Vagabond. Mine has papered balsa fins, a baffle, a 29mm motor mount, homemade motor retention, a generous length of shock cord, two beefy screw eyes (one on the base of the balsa nose cone and the other in the base of the balsa transition) and has substantial epoxy fillets along the roots of those long fins. I also filled all of the spirals in the 36" of tubing and put nice, smooth and hard finishes on the transition and nose cone.

Final weight? Without motor or parachute, it is just a hair over 6 oz. I paid no attention to the weight when I built it. (I rarely ever do.)

As I said, I don't own the kit, and there could be things that need to be done during construction that account for the final weight, but 6+ oz. seems like kind of a lot for a rocket that is the size of the Vagabond.

 

[Initiator001]

My Vagabond weighs in at 5.4 ozs (Sans motor).

Installed a baffle, longer shock cord, lot's of filler, primer, heavy coats of paint.

 

[jayarrG7]

My Vagabond weighs in at 5.4 ozs (Sans motor).

Installed a baffle, longer shock cord, lot's of filler, primer, heavy coats of paint.

Okay, as original poster, I can account for some of the difference as I upgraded to wood centering rings and kevlar shock cord with Top Flight Recovery 18" X-style thin mill chute, with swivel.

Still, every one of my rockets is heavier than stated in the specs.
That makes me wonder if the "projected altitudes" with different motors are calculated with the weight of just the parts before assembly.

 

[MarkII]

Okay, as original poster, I can account for some of the difference as I upgraded to wood centering rings and kevlar shock cord with Top Flight Recovery 18" X-style thin mill chute, with swivel.

Still, every one of my rockets is heavier than stated in the specs.
That makes me wonder if the "projected altitudes" with different motors are calculated with the weight of just the parts before assembly.

I consider the notion of finished rocket weight to be just the finished, painted rocket itself, without the recovery device or any electronic payload. It is distinct from "lift-off" or "pad" weight; the latter number is important too, but for a different reason.

Predicting altitude is a tricky undertaking. It is greatly affected not only by how the rocket in question was built and finished, but also by things like the launch site, the time of year, the weather conditions, the launch equipment and how it was set up, to name just a few. I don't take "projected altitude" as a guaranteed number, and the manufacturer doesn't intend it to be. It is more like "city/highway gas mileage," a bit of information that is useful for comparison purposes only. Way too many factors can affect the actual performance than can ever be summed up in an ad, a header card or a window sticker.

 

[bjphoenix]

I weighed some of the rockets I had handy:

Estes Firebird 2.1oz Estes says 2.1, 1998 catalog)
Estes Big Daddy 7.3oz (Estes says 5.3)
Estes Ranger 2.8oz (Estes says 3.35, 1966 catalog)
Estes Phoenix 7.7oz (Estes saya 6.6, 1998 catalog)
Estes Executioner (unpainted) 8.0oz (Estes says 8.1)
LOC Lil Nuke (modified with bigger fins) 15.0oz (LOC says 13)
LOC Vulcanite (modified with baffle) 24.2oz (LOC says 23)

 

[MarkII]

I weighed some of the rockets I had handy:

Estes Firebird 2.1oz Estes says 2.1, 1998 catalog)
Estes Big Daddy 7.3oz (Estes says 5.3)
Estes Ranger 2.8oz (Estes says 3.35, 1966 catalog)
Estes Phoenix 7.7oz (Estes saya 6.6, 1998 catalog)
Estes Executioner (unpainted) 8.0oz (Estes says 8.1)
LOC Lil Nuke (modified with bigger fins) 15.0oz (LOC says 13)
LOC Vulcanite (modified with baffle) 24.2oz (LOC says 23)

So with the major exception of the Big Daddy, the weights of the rockets that you didn't modify closely agreed with the weights listed in the catalogs for those models. (There's also a bit of deviation with the Phoenix, but that's a rather large rocket compared to the other unmodified kits on your list.) Interesting.

 

[MarkII]

The only rocket that I ever built completely stock whose weight substantially differed from the stated weight on the header card (and where the difference actually mattered) was my FlisKits Diminutive Deuce, a small MicroMaxx-powered rocket. I know exactly why mine came out being so much heavier, and it didn't have anything to do with the actual kit.

 

[shreadvector]

Using epoxy adds one to 4 ounces of wieght for no good reason.

Nylon chutes can add fatal amounts of weight to models if you attempt to use the originally recommended motors.

You often need to reduce the delay time or use a more powerful composite motor to compensate for the added weight of epoxy and nylon chutes. (And anything else added, like heavy plywood rings, heavy baffles, etc.)

As you can see from Bob's weight, he uses lightweight baffles and the proper glues. Even with a serious paint job, he is not far over the original weight. He knows what he is doing.

 

[Micromeister]

I was told years ago by Estes, Generally the package Published weight is just that "Average Shipping weight" of the raw material including packaging.
The overall mass of a finished model will depend on a number of varing things, types & amounts of glues & adhesives used, finishing methods, number of coats of paint etc.

Don't worry about that "Estes" says the model Shipping Raw weight is. Your only concern should be the Complete & finished mass of your model. With that mass info you can select proper motor(s) for your flights. Building Light is important, not slopping on a ton of glue or epoxy. but adding many color coats can also effect the overall mass as well.
Bottom line is weigh your models so You know what to expect. Here's a pic of that 500g Harbor Freight scale Powderburner mentioned. I recently saw them on sale for about 12 bucks. I've been using them for a couple years now..Great little scales for the price and as accurate as the Palm scale I paid more then triple for.

 

[geof]

If you are going to do any simulation or analysis at all, you need to weigh your own birds. And I don't mean to weigh them with the family bathroom scale, go spend the whopping $10 and get a 500 gm electronic scale (that's just over a pound capacity) at Harbor Freight or WMart or somewhere.

I strongly support this, but maybe a 3-lb limit.

The scale is especially useful in conjunction with OpenRocket or Rocksim. Sometimes, the part I am using does not roughly match the weight of a similar part in the database. More often (especially since I usually build scratch), there's no direct counterpart in shape and/or materials. Then I pick something close, weigh my own part, and do a "mass adjustment" in the software. Doing this componentwise helps you maintain the correct CG in simulations. To be picky, you can also balance each individual custom part to find its individual CG, thereby refining the estimate.

G