Estes Trajector best motors.

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Bat-mite

Rocketeer in MD
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My son launched his Estes PSII-EX Trajector for the first time on Saturday. I built it for him. I did not sim it or test it beforehand. Usually with Estes products, if you build it to spec and use the recommended motors, it is stable.

His skywrote. Broke off a fin on landing. Obviously the F15-5 was not a good motor choice. The E16 has a higher peak thrust, and that combined with a longer rail, may solve the problem.

But I was wondering if there are other motors people are using successfully. I built it with the forward motor block in place, because I assumed we would just use the F15. So any motor recommendation would need to fit into the 114mm long MMT.

Thanks.
 
A 24mm E30T SU with an adapter will fit. According to my sim, a F15 gets it up to 29ft/s and the E30 51ft/s off a 40" rod. We've also flown it on an E23 and and F40, but those are too long for your use.

I haven't tried an E16, but my sim shows it only marginally better than the F15 at 31.7ft/s.

cheers - mark
 
A 24mm E30T SU with an adapter will fit. According to my sim, a F15 gets it up to 29ft/s and the E30 51ft/s off a 40" rod. We've also flown it on an E23 and and F40, but those are too long for your use.

I haven't tried an E16, but my sim shows it only marginally better than the F15 at 31.7ft/s.

cheers - mark

I've successfully flown it on everything from an E12-4 with adapter up to a G40-10W.
It'll go REALLY high on the latter. :) [video=youtube;cFypokDRL18]https://www.youtube.com/watch?v=cFypokDRL18[/video]
[video=youtube;M0IzNWyCj9A]https://www.youtube.com/watch?v=M0IzNWyCj9A[/video]

I will say that personally the best motor has been the E18... nice flights, good altitude.
 
E20-7W is a great combo. I use the orange Estes 24-29 adapter for it.
 
Did you fly it in any wind?

What was the diameter and length of the rod?

Did you use a standoff to hold the model too high off the deflector and that prevented the model from using all of the rod?

Too slow in wind = not so stable. It will rotate into the wind and it is moving so slow that it will not stabilize once rotating. No wind for low thrust motors if fine. if there is wind, use a higher thrust motor. F26-6FJ is fine.

My son launched his Estes PSII-EX Trajector for the first time on Saturday. I built it for him. I did not sim it or test it beforehand. Usually with Estes products, if you build it to spec and use the recommended motors, it is stable.

His skywrote. Broke off a fin on landing. Obviously the F15-5 was not a good motor choice. The E16 has a higher peak thrust, and that combined with a longer rail, may solve the problem.

But I was wondering if there are other motors people are using successfully. I built it with the forward motor block in place, because I assumed we would just use the F15. So any motor recommendation would need to fit into the 114mm long MMT.

Thanks.
 
I've flown mine on F-20-7, F-23-7, and F-27-8 which were all fine, and had a pretty close ejection to apogee, interestingly two of my trajectors went dead straight, one had a roll, and one took off an a slight angle, all are build correctly and straight according to the slots so not sure why the differences, these were all in low wind conditions.
 
Saw two Majestics at Airfest that had the same trouble: stock everything, Estes BP F, skywriter's.

If I fly the replacement I'll probably put an AT reload in there.
 
Saw two Majestics at Airfest that had the same trouble: stock everything, Estes BP F, skywriter's.

If I fly the replacement I'll probably put an AT reload in there.

Was there wind?

What diameter Ann length rod was used?
 
Was there wind?

What diameter Ann length rod was used?
There was wind but well below problematic levels, no more than a light breeze.

Diameter was standard, length was standard. Weight was right at the face card, etc.

They simply didn't have the necessary speed off the rod.
 
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Did you fly it in any wind?

What was the diameter and length of the rod?

Did you use a standoff to hold the model too high off the deflector and that prevented the model from using all of the rod?

Too slow in wind = not so stable. It will rotate into the wind and it is moving so slow that it will not stabilize once rotating. No wind for low thrust motors if fine. if there is wind, use a higher thrust motor. F26-6FJ is fine.

Yes, there was wind, but it was on a 6-foot rail. I don't use rods.
 
Did you mean F-20-7 29mm as opposed to a 24mm E-20 with 7 second delay will be too long.

Well, actually, at the last second I switched to E15-7; they were cheaper. Will use the 24 -> 29 adapter. ThrustCurve says 6-second delay is optimal for the weight of my son's built rocket.
 
Did you include the motor weight and motor adapter weight?

Ejecting while plunging downward at high speed can be "BAD".

Ejecting while slowly approaching apogee is not bad.

Well, actually, at the last second I switched to E15-7; they were cheaper. Will use the 24 -> 29 adapter. ThrustCurve says 6-second delay is optimal for the weight of my son's built rocket.
 
These are aerotech E-15's? Those aren't E-15's any more they are rebranded E-20's so I'd do a sim with E-20 and see what openrocket tells you. I think 7 will be long still but 4 is probably short.

Well, actually, at the last second I switched to E15-7; they were cheaper. Will use the 24 -> 29 adapter. ThrustCurve says 6-second delay is optimal for the weight of my son's built rocket.
 
I just thought I'd second the fact that the Estes F15 isn't a great choice for this rocket. On a more-or-less windless day last year, my son's Trajector turned horizontal after leaving the pad. We built another and it has had great flights on the Aerotech F26 SU motor and the CTI F31 reload.
 
These are aerotech E-15's? Those aren't E-15's any more they are rebranded E-20's so I'd do a sim with E-20 and see what openrocket tells you. I think 7 will be long still but 4 is probably short.

buyrocketmotors.com has AT E15 three-packs and E20 two-packs. Both are WT propellant. Are you saying they're the same thing?
 
Did you include the motor weight and motor adapter weight?

Ejecting while plunging downward at high speed can be "BAD".

Ejecting while slowly approaching apogee is not bad.

ThrustCurve adds the motor weight to the sim. The paper adapter ring is negligible. Delay burns have about a 10% allowable variance, and we have a big field. We'll be fine.

I'll be glad when my kids are old enough to do DD.
 
I’ve been through this on another thread. It appears they are the same. Which is very very strange, and kind of annoying.

That's great! Because the E15s were about $10 each, whereas the E20s were about $12 each.
 
They are identical.

Many years ago there was the E15 and E30.

Then Aerotech made a molded casing to make the E20 motor to sell in two-packs with pretty labels to hang on hobby shop pegs as a direct replacement for the Estes D12 motors. Igniters worked on Estes controllers, motors fit the same models etc. With the molded casing there was a bit less room inside for the propellant so the total impulse dropped a bit.

It then became 'silly' to try to keep making the original E15 motors and E30 motors in the old style casings with so many separate components that had to be epoxied in. Also the casings may have become unavailable. So, they redesigned the E30 to fit in the E20 casing and took the E20 and simplified the label and put them in 3 packs as E15 motors. They were sold on the Valuerockets website in the 3 packs very cheap as a gateway to composite motor use.

Look at NAR S&T test data: E15 is identical to E20.

i love the current E20 (E15). I suggest the E20-4.

LOOK AT THE ACTUAL TEST DATA!!!!

-4 is actually 4.69 seconds - probably the optimal delay time for most big models.
-7 is actually 6.75 seconds
Data shows the variation in the sampled motors.

You'll have to ask yourself "Do you feel lucky today?"

buyrocketmotors.com has AT E15 three-packs and E20 two-packs. Both are WT propellant. Are you saying they're the same thing?
 
Exactly what I was saying however I had to get John to update the thrustcurve site with the E-20 data in the E-15 entry becuse it still had the old E-15 thrust curve and still does for some of the entries, if you use a simulator and use E-15 it still uses the old thrustcurve and people were seeing lower flights with the reduced E-20 badged E-15 motors becuase they are lower total impulse. That's why I mentioned it and said the -7 is probably too long.
 
Yes,

And many simulation motor databases still have the pre-2007 Aerotech motor data resulting in way higher simulation flights than real-world flights.

This has been a costly problem for TARC teams who never heard my repeated, repeated, repeated warnings about this issue.

Exactly what I was saying however I had to get John to update the thrustcurve site with the E-20 data in the E-15 entry becuse it still had the old E-15 thrust curve and still does for some of the entries, if you use a simulator and use E-15 it still uses the old thrustcurve and people were seeing lower flights with the reduced E-20 badged E-15 motors becuase they are lower total impulse. That's why I mentioned it and said the -7 is probably too long.
 
Yes, I think it was your warning that got me to check thrustcurve and notify John. It's also somewhat hazardous when people buy E-15PW thinking they are gettng that and put them in rocket gliders that now have an 8.5# peak thrust....
 
I was going to fly my Trajector next weekend some BP E15s and now I'm not so sure... I'll have at least one AT E15-4 and one E15-7 available, so maybe I'll just go with one of those and the 24-29 adapter.

Bat-mite, did you ever get a chance to fly the Trajector on the E15-7? How did the 7s delay work out?
 
I was going to fly my Trajector next weekend some BP E15s and now I'm not so sure... I'll have at least one AT E15-4 and one E15-7 available, so maybe I'll just go with one of those and the 24-29 adapter.

Bat-mite, did you ever get a chance to fly the Trajector on the E15-7? How did the 7s delay work out?

it's just mindsim and correlation with other rockets but I wouldn't fly a -7 in anything much bigger than BT-60. Most of my BT-60 rockets sim to 5-6 sec optimal delays on E's... I use E15-4s for my 3/4 lb, 3" Saturn 1B if that helps. It's a little slow off the pad but the delay is spot on.
 
it's just mindsim and correlation with other rockets but I wouldn't fly a -7 in anything much bigger than BT-60. Most of my BT-60 rockets sim to 5-6 sec optimal delays on E's... I use E15-4s for my 3/4 lb, 3" Saturn 1B if that helps. It's a little slow off the pad but the delay is spot on.
Thanks for clearing the fog in my head. Now that I think about it, I originally purchased my E15-7s to fly in my Solar Warrior which is a BT60 and about half (or even less than half) the weight of the Trajector. E15-4 it is!
 
I was going to fly my Trajector next weekend some BP E15s and now I'm not so sure... I'll have at least one AT E15-4 and one E15-7 available, so maybe I'll just go with one of those and the 24-29 adapter.

Bat-mite, did you ever get a chance to fly the Trajector on the E15-7? How did the 7s delay work out?

Not yet. Last club launch day i could attend had pouring rain. Will try for 6/16.
 
Hmm, I’ve flown my Trajector on Es and Fs with no problems though I typically only launch in as low wind conditions as possible - the local park has a lot of trees around the largest open area. I do have a 6 ft, 1/4” diameter launch rod.
 
I flew mine on an AT E15-4 yesterday, inside one of the Estes red plastic adapters. Wind was fairly light, probably less than 5 mph. Excellent flight, almost arrow straight. Unfortunately, as is commonly the case, I had too many things going on in my brain to remember to judge the ejection delay. My subjective impression is that it was a pretty goo; if the main opened early it was not by much. I'll definitely be using this motor again in the future to fly this.

One change I will make, though, is either to get a Chute Release in there (would need to buy on first LOL) or else just reef the chute a bit. The full 24" chute seems like more than this rocket needed, given that it is pretty stout. Mine drifted a fair bit in a bad direction (over a stand of trees onto an adjacent farm) but miraculously I was able to find it without excessive searching, and it's ready to fly again.
 
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