How to Choose an AeroTech RMS Motor Case Size
By Quest Q-jet | Published: 2026-10-16
Category: Buying Guides
Pick the right AeroTech RMS case by matching reload kits, rocket weight, and field size. Compare 29mm, 54mm, and 75mm hardware with clear decision rules.
Quick answer
Choose your AeroTech RMS case by the reload kit you can actually buy and fly, not by impulse alone. For most mid-power rockets, start with a 29mm case like the AeroTech RMS-29 100 N-sec (2910C). For larger high-power builds, match the case to the reload kit's required hardware: the RMS-75/5120 reload needs 75mm hardware, while the RMS-75/7680 case (7576C) is for its own reload family. Never mix high-power and mid-power RMS reloads.
Why reload kit availability decides your case size
The case is just the reusable pressure vessel; the reload kit is the consumable that determines impulse, delay, and propellant. Before you buy any case, confirm which reload kits are in stock and legal for your field. A 29mm 100 N-sec case like the 2910C uses AeroTech RMS-29/100 reloads. A 75mm 7680 N-sec case like the 7576C uses RMS-75/7680 reloads. If your local vendor only stocks one reload family, that family should drive your case purchase.
AeroTech explicitly warns that high-power RMS reload kits are not compatible with mid-power RMS products. That means a 29mm high-power case and a 29mm mid-power case are not interchangeable even though the diameter matches. Always check the reload kit's hardware requirement before assuming a case will work.
Match case volume to rocket weight and field size
Case size sets the maximum propellant volume, which sets total impulse and thrust duration. A heavier rocket or a short, slow flight needs more total impulse. A small field or a lightweight rocket needs less. The 29mm 100 N-sec case is a good fit for small fields and mid-power rockets. The 75mm 7680 N-sec case is for large high-power projects that need long burn time or high total impulse, and it requires a correspondingly large field and waiver.
Do not buy a larger case than your current reload budget and field access support. A 75mm case without a local source of 75mm reloads becomes a shelf ornament. If you are unsure, buy the smaller case first and add a larger one only when your rocket and field are ready.
Single-use vs reloadable: a parallel decision
If you are not ready to commit to reusable hardware, a single-use motor like the AeroTech K850DM-16A 54mm DMS kit is an alternative. It is assembled by the user, but all components are disposable and the nozzle and propellant are already installed. You still need the Universal Delay Drilling Tool (UDDT, not included) to set the delay and then pour the ejection charge. Single-use motors cost more per flight but avoid the upfront hardware purchase and the need to clean and rebuild a case.
Reloadable cases like the 2910C or 7576C cost more initially but lower your cost per flight once you own the hardware. The trade-off is assembly time and the need to buy the correct reload kit each time. Choose single-use if you fly rarely or want the simplest path to a specific impulse. Choose reloadable if you fly often and want flexibility across multiple reload kits in the same case size.
Hardware completeness and assembly requirements
A reloadable case is not always a complete motor. The AeroTech M1297W-PS RMS-75/5120 reload kit requires AeroTech RMS-75/5120 motor hardware to build and complete the motor, and that hardware is sold separately as a complete set or as individual parts. That reload also requires installing a forward seal disc (75FSD) during assembly. If you buy a 75mm case, confirm whether it includes the seal disc or whether you must order it separately.
For the 29mm 2910C, the case is designed for RMS-29/100 reload kits, but those reloads are sold separately. You will also need the correct delay tool and ejection charge components for your reload. Budget for these accessories before you commit to a case size, because they add to the total cost of your first flight.
Decision rules for choosing your RMS case size
- Rule 1: Start with the reload, not the case: List the reload kits you can buy locally or online. If only RMS-29/100 reloads are available, buy the 2910C. If only RMS-75/7680 reloads are available, buy the 7576C. If you need RMS-75/5120, buy that specific hardware set and the 75FSD seal disc. Checkpoint: Can you name the exact reload kit part number that fits your case? If not, do not buy the case yet.
- Rule 2: Match impulse to your field and rocket: Use 29mm 100 N-sec for small fields and mid-power rockets. Use 54mm single-use or reloadable for mid-to-large fields and heavier rockets. Use 75mm 7680 N-sec only for large high-power projects with a waiver and a large recovery area. Checkpoint: If your field is smaller than a football field, stay at 29mm or 54mm.
- Rule 3: Never mix high-power and mid-power RMS: AeroTech states that high-power RMS reload kits are not compatible with mid-power RMS products. A 29mm high-power case and a 29mm mid-power case are different systems. Always verify the reload kit's hardware requirement before purchase. Checkpoint: If the reload kit label does not say it fits your case part number, assume it does not.
- Rule 4: Budget for accessories and consumables: Reloads are sold separately. Some reloads require a forward seal disc (75FSD) or a Universal Delay Drilling Tool (UDDT). Single-use motors still need the UDDT to set delay. Add these to your total cost before choosing a case size. Checkpoint: Your first-flight cost is case + reload + tools + ejection charge. If that total is too high, start with a single-use motor.
Product facts to know before you buy
- AeroTech RMS-29 29mm 100 N-Sec Aluminum Motor Case - 2910C: CLEARANCE ITEMCANCELLED WHEN STOCK IS GONE!For use with all AeroTech RMS-29/100 high power motor reload kits. Motor reloads sold separately. Important: High Power RMS reload kits are not compatible with Mid Power RMS products. This 29mm case is a low-cost entry into high-power RMS, but it only works with RMS-29/100 reloads. If you already own mid-power 29mm reloads, they will not fit. Stock is limited, so buy only if you can source RMS-29/100 reloads locally.
- AeroTech RMS-75 75mm 7680 N-Sec Aluminum Motor Case - 7576C: For use with all AeroTech RMS-75/7680 high power motor reload kits. Motor reloads sold separately. Important: High Power RMS reload kits are not compatible with Mid Power RMS products. This 75mm case is for large high-power projects that need the 7680 N-sec reload family. It requires a matching reload kit, a large field, and a waiver. Do not buy it for mid-power rockets or if you cannot regularly buy RMS-75/7680 reloads.
- AeroTech K850DM-16A 54mm x 635mm Single Use DMS 1-Motor Kit - 118516: The AeroTech Disposable Motor System DMS is a single-use motor in kit form that is assembled by the user. All of the Aerotech DMS motors use all-disposable components. The nozzle and propellant are already installed. You will need to set the desired delay time using the Universal Delay Drilling Tool (UDDT), Not Included, and then pour in the ejection charge. The Universal Delay Drilling Tool (UDDT) is required to... This 54mm single-use motor is a good alternative if you want to fly a specific impulse without buying reusable hardware. Remember to add the UDDT to your order, because it is required to set the delay and is not included.
- AeroTech M1297W-PS RMS-75/5120 Reload Kit (1 Pack) - 13129P: The AeroTech Reloadable Motor System RMS is an aluminum cased reusable motor in kit form that is assembled by the user. You will need AeroTech RMS-75/5120 motor hardware to build and complete the motor for many reliable flights. Motor hardware is available separately in a complete set, and also as individual parts. This motor requires installing a forward seal disc (75FSD) during assembly. Important: High Power RMS... This reload kit shows why you must match the reload to the case: it needs RMS-75/5120 hardware and a 75FSD forward seal disc. If you buy a 75mm case, confirm it is the 5120 size and that you have the seal disc before flight day.
Who should choose which case size
Best for
- Flyers who can regularly buy AeroTech RMS-29/100 reloads and want a low-cost high-power entry
- High-power flyers with a large field and waiver who need the RMS-75/7680 reload family
- Flyers who want reusable hardware and lower cost per flight over many launches
Not for
- Flyers who only have access to mid-power RMS reloads, because high-power and mid-power RMS are not compatible
- Anyone without a local source of the matching reload kit, because the case cannot be used without it
- Flyers who fly once or twice a year and prefer the simplicity of a single-use motor like the K850DM-16A
