Yup, I know that. That is why I was thinking that the motor might have moved up into the tube a bit. Especially after seeing the semi-roasted aft end of the motor. It experienced some unusual hot flow on the aft end of the casing and that could have occurred when the motor slid up into the tube a bit and there was Krushnic Effect inside the aft motor retainer.

After ejection, the motor could have then slid backwards.

Only the flyer can tell us if the motor was correctly restrained to prevent forward movement.

That is why I keep a supply of spacers at the check-in table of ouor club launches. Folks come up without their 24mm C/D to E spacers all the time and I expect to see the same for the new 29mm motors. Luckily most of the time they know what they are and they have them back at their prep area. But, some of the time they have no idea what the spacer is, or where they left it.

__________________
-Fred Shecter NAR 20117 (L2)
Southern California Rocket Association, NAR Section 430

The orange ring was used and is still stuck up in the engine tube. Excuse the poor photos please. I can retake them tomorrow if I can ever get home while it is still daylight ...

First photo shows the spent motor retained. There is no crud or soot obvious on the outside of the retainer. It does have a strange pattern at the nozzle opening unlike the other four that have mostly a rounder erosion with much less black color in the actual nozzle area. I would have never noticed this had I not saved all the casings and compared later. I only question this now because it looks different from the other fired nozzles.

Photo two you can see a ring of crud around the inside of the retainer cap. No melting or signs of stress on the cap itself.

Photo three the crud only goes as far inside as the inside exposed plastic part of the screw insert where it seats against the cardboard engine tube, not onto the cardboard engine tube itself.

Photo four are the five F engines I flew. Left to right the F15-6 from the Majestic flight, the F15-6 from the Ascender flight, the center engine is from the upper stage F15-8 from my USR Sonic 160 flight, next the F15-8 from an ARG SR1720 flight, and far right is the F15-0 also fromt he Sonic 160 flight. The only other motor that shows a lot of post flight crud is the upper stage motor and that is understandable.

Photo five you can see on the F15-6 motor from the Majestic flight when the motor was removed by pushing it out with a rod where at the launch the engine was pushed past the part of the retainer causing the marks on the case. Also the other four motors can still be easily inserted into the engine mount and removed by a quick shake to drop in your hand. The Majestic F15-6 motor is swollen on the nozzle end and if reinserted, must again be pushed out from the front side with a rod. It can not be removed otherwise.


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__________________
Steve Naquin
TRA# 677 L2
NAR# 85518 L2
SAM# 0052

🚀 In Construction: Der Blue Maxx/Minie-Magg 5.5” & Vander-Burn MDRM Clone w/Stickershock23 Custom Decals
🚀 In Paint & Detail: USR Banshee
🚀 In Build Queue: Estes Doorknob w/Vander-Burn Rocketry Upgrade Kit [Sport Decor], Semroc Centurion-F, Semroc Egg Crate
🚀 In Repair: SLS Lil’ Hustler, SLS Aero-Dart 1969 Trim
🚀 Stay Tuned For Fall 2021 Launch Dates

Let me know what you think of the pictures I just posted in reply to Fred. I can try to get a better pic tomorrow that's the best I could do in the garage tonight.

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__________________
Steve Naquin
TRA# 677 L2
NAR# 85518 L2
SAM# 0052

🚀 In Construction: Der Blue Maxx/Minie-Magg 5.5” & Vander-Burn MDRM Clone w/Stickershock23 Custom Decals
🚀 In Paint & Detail: USR Banshee
🚀 In Build Queue: Estes Doorknob w/Vander-Burn Rocketry Upgrade Kit [Sport Decor], Semroc Centurion-F, Semroc Egg Crate
🚀 In Repair: SLS Lil’ Hustler, SLS Aero-Dart 1969 Trim
🚀 Stay Tuned For Fall 2021 Launch Dates

Thanks John.

I'll check out the RockSim file and try to compare as well. I am using the latest version of OpenRocket V13.09.1

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__________________
Steve Naquin
TRA# 677 L2
NAR# 85518 L2
SAM# 0052

🚀 In Construction: Der Blue Maxx/Minie-Magg 5.5” & Vander-Burn MDRM Clone w/Stickershock23 Custom Decals
🚀 In Paint & Detail: USR Banshee
🚀 In Build Queue: Estes Doorknob w/Vander-Burn Rocketry Upgrade Kit [Sport Decor], Semroc Centurion-F, Semroc Egg Crate
🚀 In Repair: SLS Lil’ Hustler, SLS Aero-Dart 1969 Trim
🚀 Stay Tuned For Fall 2021 Launch Dates

Ok, the imbalance on the crud I saw probably just came from the rotating rocket during the delay. Oh well. Thanks for the extra pics.

__________________
Roy
nar12605

OK, just to make sure we are using the same terminology:

"Erosion" is the wearing away of material. With soil, you get erosion from water washing away the soil or from wind blowing away dry topsoil. With a clay nozzle, you would get erosion if the motor exhaust removed material while it was firing.

At the resolution posted, I cannot see erosion in the photos. I do see "delay crud", which is the slag-like material produced when the delay burns. It often is deposited onto the nozzle throat and exit cone and outer/aft surface and looks like molten lava when the motor is firing (you would need to do a static test to see this). The "lava" cools and hardens to form the "delay crud" crust. Old FSI motors really had a lot of delay crud and it would form 'crudsicles' sometimes.

"Delay crud" would not occur until after thrusting, so it cannot cause any thrust vectoring. Only erosion during propellant burn (the thrust phase) can cause vectoring.

Have you taken a very detailed close up photo of the motor from that bad flight directly next to a clean unfired motor nozzle and also next to a fired motor from a good flight? Obviously you cannot post such a high resolution photo because of file size. You can also do measurements by seeing what diameter objects will fit or pass through the nozzle throat. Ditto for the exit cone aft end. Drill bits might be good to use for size guages.

__________________
-Fred Shecter NAR 20117 (L2)
Southern California Rocket Association, NAR Section 430

The nozzle on the motor in question is visually larger in diameter post firing than the nozzle on the other F motor that I also flew Saturday from the same package. Although the photos do not reference this well I can assure you it is not just delay crud in question. When viewing the end directly the opening also appears, at least to me to be more angular and eroded.

I will not pass anything through the nozzle throat until I am sure that Estes doesn't want the spent motor back for fear of knocking possible brittle clay material out of the nozzle should they want to inspect it.

The results John and I have between RockSim and OpenRocket files both show a good margin of stability on a variety of composite and black powder motors regardless of the small difference in dry weights that we reference so I don't see where it could be the fault of the rocket as far as stability is concerned or my ability to properly assemble or prepare the Majestic for flight as per the instructions. There isn't enough mass even if the parachute and shock cord was shifted all the way down to the engine mount during flight to cause instability. I can certainly produce more photographs possibly this weekend but I am willing to admit that I am not qualified to know if the motor malfunctioned in this instance or as to what these observances mean.

I really do not know what happened. Bernard had great flights using this same kit and motor configuration whereas I for some unknown reason, did not.

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__________________
Steve Naquin
TRA# 677 L2
NAR# 85518 L2
SAM# 0052

🚀 In Construction: Der Blue Maxx/Minie-Magg 5.5” & Vander-Burn MDRM Clone w/Stickershock23 Custom Decals
🚀 In Paint & Detail: USR Banshee
🚀 In Build Queue: Estes Doorknob w/Vander-Burn Rocketry Upgrade Kit [Sport Decor], Semroc Centurion-F, Semroc Egg Crate
🚀 In Repair: SLS Lil’ Hustler, SLS Aero-Dart 1969 Trim
🚀 Stay Tuned For Fall 2021 Launch Dates

You have provided an excellent report and response to all of our follow-up questions.

Check with the Estes gurus regarding taking measurements of the nozzle or returning it to them.

Maybe Dr No was involved?

__________________
-Fred Shecter NAR 20117 (L2)
Southern California Rocket Association, NAR Section 430

I left a voice message today and sent an email to Mary Roberts via the web form with a link reference to my post. Will see if Estes wants the spent engine back for any reason. Can't really say if it was the engine or if my first flight was just a fluke but will wait for instructions.

I used Bob Smith plastic CA and decided to repair the separated fins on the Majestic today, and reinforced the upper inside of the airframe tube where it had a crease in it so will fly again. I am thinking for it's next flight I will fit it with the PSII booster (when I get my grubby hands on one) and the payload section from my Ascender to house an altimeter.

I pray to the rocket gods for a good flight.

And if I see this guy on the flight line again I'm having him thrown off the launch site .....



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Attached Thumbnails

 

__________________
Steve Naquin
TRA# 677 L2
NAR# 85518 L2
SAM# 0052

🚀 In Construction: Der Blue Maxx/Minie-Magg 5.5” & Vander-Burn MDRM Clone w/Stickershock23 Custom Decals
🚀 In Paint & Detail: USR Banshee
🚀 In Build Queue: Estes Doorknob w/Vander-Burn Rocketry Upgrade Kit [Sport Decor], Semroc Centurion-F, Semroc Egg Crate
🚀 In Repair: SLS Lil’ Hustler, SLS Aero-Dart 1969 Trim
🚀 Stay Tuned For Fall 2021 Launch Dates

Do you mean the EB-70?