AeroTech Open Thread

[Initiator001]

E45 (was certified at one time) and F55 (never certified). Still have these.
View attachment 551795 View attachment 551796

The E45 was NAR certified.
The F55 was certified by TRA.

I flew several E45 and F55 motors over thirty years ago.
I flew one of each at LDRS-8 in an old MPC Yankee 1 RTF model.
The Yankee 1 survived the E45 but the F55 ripped two of the fins off the Yankee molded fin unit.

 

[Initiator001]

I still have a E25-7 in my range box. I've seen the F55 shred a rocket. The RMS 18/20 used to have a similar load. The E27, Miss those motors.

Sales were poor on those motors so they were discontinued.

 

[n3tjm]

Yeah. Now the sales for them are zero.

 

[bad_idea]

Sales were poor on those motors so they were discontinued.

I wonder if they'd be more popular in this current era of small, light trackers. (Maybe not, but a man can dream.)

 

[Nateairman]

I wonder if they'd be more popular in this current era of small, light trackers. (Maybe not, but a man can dream.)

I wonder if Rocketry as a whole shouldn't become more popular with the current situation around radio controlled flight.

Back to the 18mm E

Is it possible for an E grain to be made that works with the current 18mm hardware, even if it meant a longer case?

 

[wsume99]

Is it possible for an E grain to be made that works with the current 18mm hardware, even if it meant a longer case?

Ummmmm, if it required a longer case then wouldn't it not work with current hardware?

 

[Rocketjunkie]

Ummmmm, if it required a longer case then wouldn't it not work with current hardware?

18 mm F motors, single use (Aerotech calls them DMS). Strictly research.

 

[3stoogesrocketry]

I'll see your "research" with 1998 tech.....

But in all seriousness , you do good work Tom .

 

[wsume99]

18 mm F motors, single use (Aerotech calls them DMS). Strictly research.
View attachment 551964

yep, I was actually thinking of your work when the question was asked but I knew you weren't using any certified hardware

 

[DabCat]

Would it be possible to release motor drawings of old discontinued motors (such as the E27) on the RCS website?

 

[AeroTech]

Would it be possible to release motor drawings of old discontinued motors (such as the E27) on the RCS website?

Sure, if I can find them.

 

[smstachwick]

I’m looking at those thrust curves and I’m guessing that the E25/E27 filled the case up all the way, and the current D24T/old D21T has just a little bit of room? Am I correct on that, or was there another trick to squeeze out a few extra N-sec?

 

[AeroTech]

I’m looking at those thrust curves and I’m guessing that the E25/E27 filled the case up all the way, and the current D24T/old D21T has just a little bit of room? Am I correct on that, or was there another trick to squeeze out a few extra N-sec?

That’s pretty much it.

 

[AeroTech]

Would it be possible to release motor drawings of old discontinued motors (such as the E27) on the RCS website?

I searched the archives and I don't have them, sorry.

 

[Jay Dub 4009]

Shout out to Karl at AT. Had a 75mm reload come without orings or delay. He got them right out to me, and AT took it in the shorts for haz shipping for a stinking delay grain.

Bravo as always!

 

[Jay Dub 4009]

Love the L1390G

 

[n3tjm]

The E27-4T was pretty much the D24-4T but where the delay spacer was was propellant (longer propellant grain). This is one of the loads imo that should be made once in a while. I would buy a pack right now if it was available

 

[DabCat]

H238 CATO in my nice Dr Rocket casing . Burned through the casing just above the forward closure. Any ideas as to what caused it? Will warranty replace reload and casing in this case?

 

[rocketace]

H238 CATO in my nice Dr Rocket casing . Burned through the casing just above the forward closure. Any ideas as to what caused it? Will warranty replace reload and casing in this case?

I had something like this happen with a AT 29mm. Looks almost the same. When I took mine a part I realized I put the O-rings in the wrong place...

 

[Rocket86]

I had something like this happen with a AT 29mm. Looks almost the same. When I took mine a part I realized I put the O-rings in the wrong place...

View attachment 552348

+1. Nozzle and forward insulator o-rings reversed is my guess. I did it once with exactly the same result.

 

[n3tjm]

Most likely wrong O-ring was used. I really do LOVE the H238. I even managed to fly one this year, and still have 2 more in my range box.

 

[Theory]

What others said, likely an o-ring issue. And X3 on the H238!!!

Ignition in my Loc Minie Magg

 

[AeroTech]

H238 CATO in my nice Dr Rocket casing . Burned through the casing just above the forward closure. Any ideas as to what caused it? Will warranty replace reload and casing in this case?

Warranty issues are handled by Karl, please contact him at the email address in my sig. Sounds like you reversed the forward and aft O-rings.

 

[n3tjm]

It is always a good idea to make sure you have the correct parts with your reload before assembling. Also if you assembling a load you are not familiar with don't be afraid to ask. Twice I have seen the wrong nozzle included in a reload. One was caught when I helped a guy with a misfire and I just happened to have the same reload and was able to give him the right nozzle. The other was a J420 that catoed on a L2 cert flight. It came with the smaller 38mm nozzle, not the wider nozzles the larger 29mm and 38mm loads use. It was the flyers first J motor. Mistakes do happen, and Aerotech is usually quick in helping you out with getting you the right parts.

 

[waltr]

It is always a good idea to make sure you have the correct parts with your reload before assembling. Also if you assembling a load you are not familiar with don't be afraid to ask. Twice I have seen the wrong nozzle included in a reload. One was caught when I helped a guy with a misfire and I just happened to have the same reload and was able to give him the right nozzle. The other was a J420 that catoed on a L2 cert flight. It came with the smaller 38mm nozzle, not the wider nozzles the larger 29mm and 38mm loads use. It was the flyers first J motor. Mistakes do happen, and Aerotech is usually quick in helping you out with getting you the right parts.

How would I know the correct parts are in the reload kit?
Well some would be obvious, like O-ring size, but not a nozzle or the correct delay element.
Maybe better documentation of the parts included such as diameter of nozzle opening, etc.
Having Delay element Marked with the part number (of course they could get mis-marked).

I do follow the directions and am careful to identfy the O-rings. However, I have had two G64's from the same lot number have delays that were much longer, 5 seconds longer, then they should have been.

 

[n3tjm]

Nozzle size and delay grain size are published on Aerotech's site, but mostly for cases such as getting the right nozzle, most people will trust that the right one is included in the kit. Things like that can be caught with personal experience. Like in both of my examples, both nozzles were to small. I want to also stress that such mistakes will be rare.

 

[DabCat]

Warranty issues are handled by Karl, please contact him at the email address in my sig. Sounds like you reversed the forward and aft O-rings.
View attachment 552634

I pulled off the aft closure and it looks like the aft O-ring was the large one that should have been in the front. Since it was my mistake will warranty still cover it?

 

[rfjustin]

I pulled off the aft closure and it looks like the aft O-ring was the large one that should have been in the front. Since it was my mistake will warranty still cover it?

Sorry to see the issue you had, but why should Aerotech dig into their pocket to cover a confirmed end-user error? That does not seem reasonable to me.

 

[waltr]

The delay grain lengths are easily known however, there seems to be a number of different compounds used.
All the delays burn at 1/32" after propellant burn-out BUT have different burns rates during propellant burn.
Here is a table of delays for the 29/40-120 reloads. The HDK # then the length in inches then # of 1/32nds followed by the delay time and which reload they are to be used with and # of 1/32nds burned during propellant burn.
Last columns are the reload and the burn rate in 1/32nds inch per second time.
Last column is a letter to match burns rates under trust. I see 5 different rates and 7 different lengths.

Delay Time (s)

Delays

length

x/32's

4

5

7

8

10

11​

14

G71

Material

HDK-15

0.375​

12

G76 \8

E23 \7

E23 \4.4

G76 \5.3

A

16

0.406​

13

F52 \8

G71 \6

F52 \5.7

B

17

0.5​

16

F40 \12

G53 \9

E23, F52 \8

E23 \5.3

F40 \5.7

F52 \5.7

G53 \5.3

B

18

0.531​

17

G64 \9

F52 \6

F52 \4.3

G64 \4.7

C

19

0.562​

18

E16 \14

G76 \8

E16 \7.0

G76 \5.3

A

20

0.657​

21

G64 \14

G53 \11

G53 \6.5

G64 \7.4

D

21

0.657​

21

E16, F40 \14

G64 \11

F16 \7

F40 \6.6

G64 \5.7

A

22

0.75​

24

F22, G33 \19

F40 \14

F22 \5.7

F40 \6.6

A

23

0.75​

24

F22, G33 \17

F22 \5.2

E

24

0.75​

24

G53 \19

G53 \11.2

F

25

G76

G

 

[DabCat]

Sorry to see the issue you had, but why should Aerotech dig into their pocket to cover a confirmed end-user error? That does not seem reasonable to i

I wasn't expecting them to warranty it, but Aerotechs response sounded like they might, so I got a little confused. My bad.