L1 Build - Aerotech G-Force

I realize this rocket was designed to fly on G motors but I plan to use it for getting my Level 1 cert so I placed this thread in the HPR section. I also plan to build it light enough so I can fly it on G motors without needing a waiver.

Here are the mods I'm planning for this build:

• Shift MMT rearward so the motor extends out past the bottom of the BT - this should help eliminate damage to the bottom of the BT
• Aeropack motor retainer
• Additional CR at the rear of the rocket
• Replace stock baffle with a set of half moon baffles
• Altimeter bay between the upper bulkhead and NC
• Upgrade shock cord and recovery hardware

I've checked the stability in OR with the MMT shifted to the rear as I plan to do and with a 29mm 6XL case the stability is 1.47. So I should be good without needing any nose weight. I'm hoping to get started on this build within the next week or so.

wsume99 said:

I realize this rocket was designed to fly on G motors but I plan to use it for getting my Level 1 cert so I placed this thread in the HPR section. I also plan to build it light enough so I can fly it on G motors without needing a waiver.

Here are the mods I'm planning for this build:

• Shift MMT rearward so the motor extends out past the bottom of the BT - this should help eliminate damage to the bottom of the BT
• Aeropack motor retainer
• Additional CR at the rear of the rocket
• Replace stock baffle with a set of half moon baffles
• Altimeter bay between the upper bulkhead and NC
• Upgrade shock cord and recovery hardware

I've checked the stability in OR with the MMT shifted to the rear as I plan to do and with a 29mm 6XL case the stability is 1.47. So I should be good without needing any nose weight. I'm hoping to get started on this build within the next week or so.

Click to expand...

I plan to use mine for L1 as well but all I did was beef up the recovery system with a kevlar blanket and shockcord with kevlar, elastic and tubular nylon, remove the cooling mesh, beef up the aft end and install a PMR.
I plan to use a 29mm "H" motor probably an H128 or H250 which folks here and thise in my club say will handle the L1 nicely.

wsume99 said:

I realize this rocket was designed to fly on G motors but I plan to use it for getting my Level 1 cert so I placed this thread in the HPR section. I also plan to build it light enough so I can fly it on G motors without needing a waiver.

Here are the mods I'm planning for this build:

• Shift MMT rearward so the motor extends out past the bottom of the BT - this should help eliminate damage to the bottom of the BT
• Aeropack motor retainer
• Additional CR at the rear of the rocket
• Replace stock baffle with a set of half moon baffles
• Altimeter bay between the upper bulkhead and NC
• Upgrade shock cord and recovery hardware

I've checked the stability in OR with the MMT shifted to the rear as I plan to do and with a 29mm 6XL case the stability is 1.47. So I should be good without needing any nose weight. I'm hoping to get started on this build within the next week or so.

Click to expand...

My brother recently did his L1 on this rocket using an CTI H410 V-Max (3 grain) to mitigate weather cocking; it was straight up, chute popped just over 1000 feet, short landing, short walk, done.

He ended up adding some nose weight as the predicted vs CG was a bit further aft so this gave him a bit margin for stability when using bigger motors. His configurations was the following:

• Aeropack retainer
• Fixit epoxy fillets just to give a better finish to the fins (likely a big source of the extra weight)
• remove-able rivets on the nosecone to the payload section
• Jolly logic altimeter hanging from nosecone hook
• 20 foot 1500 lb kevlar shock cord
• swivel and 1/8th" quick link for quick swap out of the recovery depending on the conditions
• I think he also used one of my Fruitychutes 42" Classic Elliptical chutes instead of the stock 42"
• I can't recall if he removed the cooling mesh and opted for a nomex or not, he may of just to leave the MMT open for a bigger reload

Good luck, it's one of many good choices for a successful L1, those Aerotech kits can handle H motors no problem, of corse that depends on how you put it togther.

mpitfield said:

My brother recently did his L1 on this rocket using an CTI H410 V-Max (3 grain) to mitigate weather cocking; it was straight up, chute popped just over 1000 feet, short landing, short walk, done.

He ended up adding some nose weight as the predicted vs CG was a bit further aft so this gave him a bit margin for stability when using bigger motors.

Click to expand...

I'm going recheck my CG and run some more sims after its done. I don't want to add permanent nose weight because that will make it more difficult to stay under the 1500g waiver limit. If I need to add nose weight for bigger motors then I'll attach some to the bottom of the NC so it can be removeable.

I am curious why you plan to add a centering ring to the rear and hope it isn't concern about thrust. If you epoxy your fins into the fin locks and then very lightly to the body tube they will transfer all of your thrust quite nicely.

Tim at Apogee Rockets mentions using the rocket for L1 without modification. I would certainly lose the motor block, and their cooling mesh (or ensure you can pull it back out to clean). I can also easily see the upgrade to the elastic they provide.


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1tree said:

I am curious why you plan to add a centering ring to the rear and hope it isn't concern about thrust.

Click to expand...

I'm doing it for two reasons -
1) It should provide some rigidity to the aft end of the sustainer and help protect against damage during touchdown.
2) Cosmetics. There will be several inches between the bottom of the BT and the CR at the rear of the fins. I don't want that hollow space showing.

I'm wondering what everyone's thoughts are on nomex vs. half moon baffles? I'm partial to the baffles because I've used them before. It just seems easier not having to fuss with a blanket every time I pack the recovery gear although I've never actually used a nomex blanket so maybe I'm wrong?

wsume99 said:

I'm wondering what everyone's thoughts are on nomex vs. half moon baffles? I'm partial to the baffles because I've used them before. It just seems easier not having to fuss with a blanket every time I pack the recovery gear although I've never actually used a nomex blanket so maybe I'm wrong?

Click to expand...

Maybe add a few pieces of Dog Barf under the chute for "cheap insurance".

JP

When I had my G-FORCE I changed the following

AP Retainer
Added rear center ring which allowed the AP retainer to butt flush against it
Removed the cooling mesh and went with Nomex blanket
Added a nomex shock cord protector
Upgraded the chute to a Topflight 45"
Epoxy fin fillets
Reinforced AFT body tube with Giant Leap coupler and also coated it with epoxy

wsume99 said:

I'm wondering what everyone's thoughts are on nomex vs. half moon baffles? I'm partial to the baffles because I've used them before. It just seems easier not having to fuss with a blanket every time I pack the recovery gear although I've never actually used a nomex blanket so maybe I'm wrong?

Click to expand...

The cooling mesh actually dioes work. How much fuss is a blanket. I don't get it. Take your time and prep your rocket for flight because if you are launching with a club its just gonna sit on the pad.

wsume99 said:

I'm doing it for two reasons -
1) It should provide some rigidity to the aft end of the sustainer and help protect against damage during touchdown.
2) Cosmetics. There will be several inches between the bottom of the BT and the CR at the rear of the fins. I don't want that hollow space showing.

Click to expand...

I did the same thing for the same reasons. Wish I would have remembered to do so on my SUMO

AfterBurners said:

When I had my G-FORCE I changed the following

AP Retainer
Added rear center ring which allowed the AP retainer to butt flush against it
Removed the cooling mesh and went with Nomex blanket
Added a nomex shock cord protector
Upgraded the chute to a Topflight 45"
Epoxy fin fillets
Reinforced AFT body tube with Giant Leap coupler and also coated it with epoxy

Click to expand...

I've been using your build thread for inspiration. That was one nice looking rocket. It looks like you installed the mmt in the stock position?

wsume99 said:

I've been using your build thread for inspiration. That was one nice looking rocket. It looks like you installed the mmt in the stock position?

Click to expand...

Yes I did. That's why I went ahead and installed that extra aft ring. It took away that gap between the stock aft ring and the end of the mmt. When you install the retainer it just gives it a much cleaner look.

What I would do is dry fit the retainer and install the aft ring and make a mark on the mmt. Sometimes it can be difficult to get the last ring on perfect so what would help is to use a small center ring that has a lip that fits over the 29 mmt. So you get a visual, it would be like fitting a BT-55 ring over a 24mmt. The thickness of the ring would act as a support and align the aft ring. Position the ring just under the tick mark and CA or epoxy it in place. You could then apply your epoxy to the airframe and easily slide the aft ring into position and it would butt flush against the lip of the CR. I used to eye screws to HELP hold it in place and manuver it, which you can also use with this method. Once the epoxy sets up just attach the retainer and you are good to go. It should align perfectly and there will be no excess.

I also strongly suggest usually a tube coupler after you get the ring installed for added support and to reinforce the aft section of the airframe. You will be happy with the results.

Added Note: You can make your own center ring out of card stock or another material. You could have a lip of about 1/4" on it

PM me if you have any questions or concerns?

Thanks AB. I hadn't thought of using a bushing on the OD of the mmt to help position the aft CR.

I opened the kit the other day and weighed all the components. The eyebolts that are provided are pretty pathetic. They look to be standard #8 eyebolts with screw threads. I'm not really comfortable using them so I will be replacing them. What is the best option? Forged eyebolt, aluminum U-bolt? Something else?

wsume99 said:

Thanks AB. I hadn't thought of using a bushing on the OD of the mmt to help position the aft CR.

I opened the kit the other day and weighed all the components. The eyebolts that are provided are pretty pathetic. They look to be standard #8 eyebolts with screw threads. I'm not really comfortable using them so I will be replacing them. What is the best option? Forged eyebolt, aluminum U-bolt? Something else?

Click to expand...

I would upgrade them maybe a size or two bigger. Just run down to Home Depot or your local hardware store. I think the eye screw would work fine. Just epoxy it in place.

I used stainless 1/4" u bolts on mine. probably way overkill but I had them lying abound.

Derek said:

I used stainless 1/4" u bolts on mine. probably way overkill but I had them lying abound.

Click to expand...

definitely overkill... for me I just try to stick with the stock build...keep it lite but strong.

AfterBurners said:

definitely overkill... for me I just try to stick with the stock build...keep it lite but strong.

Click to expand...

yeah, but the stock ones are really quite whimpy.

Derek said:

yeah, but the stock ones are really quite whimpy.

Click to expand...

I agree. It should be an actual eye bolt not an eye screw. I just don't trust that tiny eye screw threaded into a fiber bulkhead or CR. Of course it could be just fine but why take the risk?

I used mine for L-1.

Only changes I made:

use TN instead of supplied elastic.

leave off motor hook.

section of coupler to beef up aft end of airframe.

It's still going strong after 11 yrs!

I have replaced the mesh with STAINLESS ChorBoy twice .

I did use the stock baffle & screw eye & chute.

When flying H-motors, only use 1 gram of supplied BP.

Folks tend to overthink & build these things. It will work & last just fine with very simple mods.

Blackjack is right....why spend the extra cash. I still have the stock chute, but I might use a 45 instead because I'm launching on a dry lake bed. All you are doing is adding extra weight with all that hardware. I even use the stock shock with Nomex shock cord protector and blanket. I still have the piston but wanted the extra room to pack the laundry