At E-30 Question

[Steward]

OK...I built an Estes PHEONIX sturdy but stock.. It turns out real heavy...
It's first flight was on a D 12 5 which picked it up about 40-45 feet and of course the parachute ejected after it dropped back to the ground...just enough to pop a fin off...
I've repaired that and bought AT E30's...one 4 second and one 7 second delay.
Here's the question...What can or should I expect with either motor? I don't want to rip it up with a too short 4 second delay if it's still climbing... on the other hand we don't want a lawn dart because 7 seconds is too long...
By the way...this is my first attempt at mid power...
What does anyone suggest...??? THANKS in advance...!!!

 

[vjp]

Only 40-45 ft. from a D12-5? It must have built REAL heavy (lots of excess nose weight?)

First, if you're going to fly it on an E30, you should have built it strong - especially the fins, shock cord, and chute. I wouldn't trust a plastic chute here, since a high speed deployment is likely unless you peg the delay right on.

Second, can you weigh the rocket? That way an accurate sim could be run.

As it stands, if I had to guess (because it reached only 45 ft. on a D12-5) I would say a -4 delay would be the safer bet. But I can't believe it reached that low of an altitude just because it was a little heavy - could something else have gone wrong (nozzle blowout)?

 

[Steward]

It's quite possible that something went wrong with the motor...I don't know...I built it strong on purpose using heaveir than normal fillets inside and out...at least three coats of primer, sanded in between, and I think two top coats ...all Krylon.
I thought it funny that it didn't do any better than that...I just blew it off as being too heavy...
But...now that you mention it, a previous PHEONIX (years ago) lofted to 300 to 400 feet on a "D"...not sure of the delay...
Im going to buy a scale...been meaning to for a while...so I'll measure it this evening...Having said that...could/would you or someone run a rocsim??? That would be the best way....!!!
The E-30 will fly...I just don't know to where...LOL
THANKS....
as I've always said....
"TFR ROCKS"

 

[Len B]

Originally posted by Steward


measure it this evening...Having said that...could/would you or someone run a rocsim??? That would be the best way....!!!
The E-30 will fly...I just don't know to where...LOL
THANKS....
as I've always said....
"TFR ROCKS"

I just ran a sim of the Phoenix. This file was part of the RockSim software and I didn't write it but it seems good. First, it indicates a built weight of 117 grams empty. That seems a bit light but if you weigh it and post here, I will load the real weight and run it again. On an Estes D-12-3, it sims to 300 or so feet. That sounds more like it. There have been some nozzle issues with D-12's a while back as I recall. The AT E-15-4 would be a good choice for a motor as it is only a bit more average thrust than the D-12 and should take it to 1000 feet at 200 mph! The optimal dealy is 3.87 seconds Cool! The AT E-30-4 is a bit short on the delay with 4.25 seconds being optimal. It takes it to 863 feet at a max. speed of 314 mph.

If you have one, an E-15-4 is cool assuming a weight close to stock.

Let me know the weight and CG and I can do the sims again.

Len Bryan

 

[vjp]

I don't have a completed Phoenix, but I do have one 1/2 built, on my workbench. Weighing the components built, plus those left to go, I get 6.5 ounces. I figure another 1.5 ounces for primer, glue, and paint, putting the finished weight at 8 ounces (w/o motor).

With that weight, I get an optimal delay of 5 seconds on an E30, so a -4 should do just fine. A -7 will probably be acceptable, too, provided you don't get a "bonus" delay.

Here are some of my sim results:

Motor Optimal Delay Max Velocity Max Alt.
Estes D12 3.3 94 mph 340 ft.
AT E15 4.4 176 mph 893 ft.
AT E30 5.0 237 mph 839 ft.
Estes E9* 3.83 118 mph 596 ft.
AT F21* (Econojet) 4.74 241 mph 1097 ft.


(*assuming no extra nose weight needed for stability, as these are heavier motors).

 

[el chubbo]

I weigh almost everything on the postal scale that they have at my local Kinkos.... it will give a perfect weight in oz, lbs or grams...

I am sure that any place that handles postage will do the same for you...

It's always fun walking into a Kinkos with a rocket!

 

[BlueNinja]

Guess next time i go to Lawrence I oughta try the kinkos there...

I would say the -4 would be good with this roc...

 

[Steward]

It's funny that Kinkos was brought up...
Although I really want to buy a set of scales, I haven't been able to get out this weekend... I hope to do so...in the meantime I've e-mailed our club newsletter to Kinkos to be printed, and have to go tomorrow to pick them up...
Two birds with one stone so to speak...I bet it is funny to walk into Kinkos (or anywhere) with a big rocket like that...LOL