Max. Take Off Weight For Estes E-9 & D-12? (Mean Machine)

[Peter]

I have nearly completed an Estes Mean Machine modified for E-9's or better using epoxy, basswood fins, middle instead of nose cone ejection etc.
Can anyone provide me with recommended max. take off weight for these 2 motors? I'm afraid I may have gotten carried away with my mods. and made it too heavy. Thanks - Peter

 

[Fore Check]

Well, this information is straight from their current catalog's engine chart:

           Max Lift off Weight
Engine       Ounces    Grams
------       ------    -----
D12-3         14.0      396
D12-5         10.0      283
D12-7          8.0      226
E9-4          15.0      425
E9-6          12.0      340
E9-8          10.0      283

Hope this is what you were looking for!

 

[rabidsheeep]

uhh... well, that cant be right... ive gotten heavier things off on d12's

 

[shreadvector]

Those numbers are from a standard chart which is a GENERAL guideline. It is for average models with average characteristics launched from an average launch pad in average wind conditions.

As I've explained in great detail (with photos on the jimz gallery page to back it up), you can launch an Estes Maxi V-2 with an E9-4 IF you follow the following advice:

1) Build it stock, do not add tons of paint or epoxy. Stock lift off weight with E9-4 is between 1 pound and 1.1 pounds. They made the plastic nose and tail cone too thick so they came out heavier than the original release in the 1970's.

2) launch from a 1/4" dia x 6 foot steel launch rod (or use a rail). It needs the longer rod to build up airspeed to continue to fly "up".

3) Launch with zero or very little breeze.

Originally posted by rabidsheeep
uhh... well, that cant be right... ive gotten heavier things off on d12's

 

[atticus]

The Estes figures may be conservative, but as Shreadvector said many factors need to be considered.
We recently overbuilt an 'HGA - Dishonest Johnson' with TTW fins and epoxy and J-B weld, but left the MMT at 18mm. We should have gone for 24 but we use a small field and didn't want to lose it.
After finishing and weighing, it was 13 grams over Estes' MLW with a C6. Bummer.
Then I run into a simple online simulation program that I can't find now and plugged in the figures. 332 feet! What to do?
Well, I had used a 3/16" LL and on a perfectly calm day loaded it with a C6-3 on a 5 foot rod, gave a very loud 'heads up" and had a kid push the button (70 feet away from the pad relay box). Fine flight, ejection at apogee and touch down 50 feet from pad. Every objective observer agreed - "Yeah, that looks like 300 feet".
Two more flights that day with identical results.
However, I must agree that many factors need to be considered before launching any questionable rocket. Safety first!
Beautiful rocket,but I WILL NOT launch it in wind.
Now we just wait for Aerotech to get some 18mm stuff out there.

 

[Stymye]

like shread mentioned

launch speed off the rod is also critical..a nice stable rocket might fly nice and slow to a low altitude..but a different design might not
be pretty, don't necessarily rely on altitude data alone..