Engine change on Estes Redstone

[Doug Foster]

The Estes Redstone model only achieves 200 ft (according to their website) so I was planning to convert from the 18mm motor to 24mm motor to get to a decent altitude. I have ordered the motor conversion kit from Estes but I am concerned with the CG moving aft and possible stability issues. If Estes would indicate where the the center pressure is on all rockets that would help. I know on my S1B they do indicate where the CG needs to be. Anyone every do a motor conversion like this?

 

[Joekeyo]

The Estes Redstone model only achieves 200 ft (according to their website) so I was planning to convert from the 18mm motor to 24mm motor to get to a decent altitude. I have ordered the motor conversion kit from Estes but I am concerned with the CG moving aft and possible stability issues. If Estes would indicate where the the center pressure is on all rockets that would help. I know on my S1B they do indicate where the CG needs to be. Anyone every do a motor conversion like this?

No. But it flies nice on "D" Q-JETs

 

[Doug Foster]

No. But it flies nice on "D" Q-JETs

Awesome--thanks! I was not familiar with these-

 

[BEC]

Q-Jet C12-4 and D16-4 would likely make your Redstone go fairly nicely. The C12-4 takes the RTF 1/200 Saturn V almost twice as high as the Estes C5-3 does, on only about 1.5 more Newton-seconds.

And the the weights are very close (Q-Jets a touch lighter I think). So if you've already built it with an 18mm mount this is the way to go.

Q-Jets are composite motors made by Aerotech and sold under the Quest name.

C12/D16FJ (FJ for "Fast Jack") have a thick black smoky exhaust and are easy to light.
C18/D20W (W for White Lightning) have a bright white flame and less smoke but are a little more fussy about getting going. Also with the higher thrust at the same total impulse (9.8 N-s for the Cs, a bit under 14 N-s for the Ds) they actually will take most models to a lower apogee because of the increased drag from the higher speeds.

 

[cls]

The Estes Redstone model only achieves 200 ft

That's still suborbital, so you score mission points! Maybe don't guild the lily?

 

[lakeroadster]

What the heck, upgrade it to 29mm, not that much bigger, and you can do a moon shot.

 

[Aeva]

While you're at it, scrap the redstone and put an atlas rocket on that thing lol (jk)

(do it though, I'm with @lakeroadster : go 29mm. You can always get motor mount adapters if you want to take an easy on a launch or two)

 

[Doug Foster]

Q-Jet C12-4 and D16-4 would likely make your Redstone go fairly nicely. The C12-4 takes the RTF 1/200 Saturn V almost twice as high as the Estes C5-3 does, on only about 1.5 more Newton-seconds.

And the the weights are very close (Q-Jets a touch lighter I think). So if you've already built it with an 18mm mount this is the way to go.

Q-Jets are composite motors made by Aerotech and sold under the Quest name.

C12/D16FJ (FJ for "Fast Jack") have a thick black smoky exhaust and are easy to light.
C18/D20W (W for White Lightning) have a bright white flame and less smoke but are a little more fussy about getting going. Also with the higher thrust at the same total impulse (9.8 N-s for the Cs, a bit under 14 N-s for the Ds) they actually will take most models to a lower apogee because of the increased drag from the higher speeds.

Interesting-thank you! Yes I see "Black Max" and "White Lightning" propellents listed on the Aerotech Master Motor Matrix. I don't understand why the C12-4 (9.8 total impulse; 17.5 max) would achieve 2x altitude vs the Estes C5-3 (10.0 total impulse; 20.4 max) on the 5oz S5 model???

 

[Back_at_it]

The QJets are a good choice but you are still more than stable with a 24mm in a stock Redstone. No extra nose weight needed. You might want a larger chute as there is a touch more weight down low and the fins are fragile

 

[BEC]

Interesting-thank you! Yes I see "Black Max" and "White Lightning" propellents listed on the Aerotech Master Motor Matrix. I don't understand why the C12-4 (9.8 total impulse; 17.5 max) would achieve 2x altitude vs the Estes C5-3 (10.0 total impulse; 20.4 max) on the 5oz S5 model???

First of all, the Estes C5-3 is 7.79 N-s (see https://www.nar.org/SandT/pdf/Estes/Estes_C5_2019.pdf) and the Estes C6 is 8.82 N-s (https://www.nar.org/SandT/pdf/Estes/C6.pdf) You are correct that 9.8 N-s is the certification total impulse value for the C12FJ.

I've flown altimeters in just about everything. There is some magic in the Q-Jet C12s as they carry most any model, especially a heavier one, quite a bit higher than an Estes C6 or C5. I just went back in my logs as the 1/200 Saturn V is one I didn't fly an altimeter in every time, and I haven't actively flown for five years. So back in May of 2019 I have these data:

Flight 1 - (May 5, 2019) Estes C6-3 altitude 199 feet (via FS Mini)
Flight 2 - (May 12, 2019) Q-Jet C12-4 altitude 348 feet (via FS Mini)
Flight 8 - (July 11, 2019) - Estes C6-3 altitude 212 feet (via FireFly)
Flight 9 - (July 16, 2019) - Q-Jet C12-4 altitude 344 feet (via FireFly)
Flight 10 - (the same day) - Q-Jet D16-4 altitude 433 feet (via FireFly)


I haven't found any entries where I've flown this model on the C5-3 with an altimeter, though I thought I had. I may still keep looking but right now I want to go fly before the rains come back this evening.

So I exaggerated a little when I said "twice as high".

I've seen similar results with the Estes MAV, which is another heavy plastic model, though not as heavy as the little Saturn V.

 

[rcktnut]

The Estes Redstone model only achieves 200 ft (according to their website) so I was planning to convert from the 18mm motor to 24mm motor to get to a decent altitude. I have ordered the motor conversion kit from Estes but I am concerned with the CG moving aft and possible stability issues. If Estes would indicate where the the center pressure is on all rockets that would help. I know on my S1B they do indicate where the CG needs to be. Anyone every do a motor conversion like this?

CP at 23.13 in.

 

[Doug Foster]

First of all, the Estes C5-3 is 7.79 N-s (see https://www.nar.org/SandT/pdf/Estes/Estes_C5_2019.pdf) and the Estes C6 is 8.82 N-s (https://www.nar.org/SandT/pdf/Estes/C6.pdf) You are correct that 9.8 N-s is the certification total impulse value for the C12FJ.

I've flown altimeters in just about everything. There is some magic in the Q-Jet C12s as they carry most any model, especially a heavier one, quite a bit higher than an Estes C6 or C5. I just went back in my logs as the 1/200 Saturn V is one I didn't fly an altimeter in every time, and I haven't actively flown for five years. So back in May of 2019 I have these data:

Flight 1 - (May 5, 2019) Estes C6-3 altitude 199 feet (via FS Mini)
Flight 2 - (May 12, 2019) Q-Jet C12-4 altitude 348 feet (via FS Mini)
Flight 8 - (July 11, 2019) - Estes C6-3 altitude 212 feet (via FireFly)
Flight 9 - (July 16, 2019) - Q-Jet C12-4 altitude 344 feet (via FireFly)
Flight 10 - (the same day) - Q-Jet D16-4 altitude 433 feet (via FireFly)


I haven't found any entries where I've flown this model on the C5-3 with an altimeter, though I thought I had. I may still keep looking but right now I want to go fly before the rains come back this evening.

So I exaggerated a little when I said "twice as high".

I've seen similar results with the Estes MAV, which is another heavy plastic model, though not as heavy as the little Saturn V.

Excellent-thanks man; helps a lot!

 

[Doug Foster]

CP at 23.13 in.

View attachment 643585

Great -thanks for the CP!

 

[Doug Foster]

The QJets are a good choice but you are still more than stable with a 24mm in a stock Redstone. No extra nose weight needed. You might want a larger chute as there is a touch more weight down low and the fins are fragile

Thanks!

 

[Ronz Rocketz]

Mine didn't go very high on a C18. This was back when I was more cavalier with my JLCR. I got tired of the tabs breaking off so later bought the builders kit from Boyce with the 3D printed can BT-80.

 

[BEC]

In my experience C18s take a model lower than C12s, even though the total impulse is essentially identical. I believe that is because of the higher speeds from the higher thrust. Drag increases with the square of velocity. The C12 just seems to be in a sweet spot with respect to this.

 

[Ronz Rocketz]

The main problem I've had with the Q-jet is with chuffing, sometimes igniting off the rod. I can add an inch of cannon fuse to the 24mm motors but not the 18mm motors. Empirically, this helps the motor to decide when it wants to go after the initiator goes off.



I learned this trick from Jake but alas, he didn't add to his G80 and his Mega Max chuffed.