Kevlar Ultimate Fuel Buffer UFBK series.

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  • Regular price $109.00

 This is a military spec light weight device that functions as an air trap and fuel buffer system for Unmanned Aerial Vehicles and RC planes.

It is designed and assembled in the USA by Ultimate Jets from certified  MIL spec components and derived from a unit that complies with MIL-STD-810G parts 513.6, 514.6, 516.6 and 520.3.

The UFBK series are constructed from pressure molded monocoque kevlar tanks and Al 6061 screw type stopper assembly as well as SLA 3D printed vibration and shock absorbing mount. The manufacturing process of the machined and 3D printed parts is certified to a high precision of 50 micrometer or 0.0020". 

The kevlar tank is pressure molded in an aluminum mold and cured in a high temperature autoclave.




The units are sized to be useable with jet engines from 100 N of thrust to 1000 N of thrust class. The ref number of the UFB relates to its max rated thrust.

We recommend setting it up according to the Industry best practices.


The advantages of this air trap compared to other products on the market:

1. Very high strenght-to-weight ratio.

2. High buffer capacity offering large air retention capability and very low suction drag.

3. Fully serviceable with large fittings that can be ordered/ swapped to the customer requirements. Filter is replaceable and available here.

4. Superior resistance to cavitation

5. Extremely high manufacturing quality and resistance. Superior resistance to vibration thanks to its unique 3D printed mounting system.

6. Vaccutest system on 250 and 160 sizes

7. Very strong mounting solution and overall design.

8. Designed for UAV and extreme RC applications.


As a reminder, the main reason for fitting an air trap in the fuel system is to cater for the non perfect clunk pickup. No matter how good the clunk system is setup, you will always end up sucking some air while emptying your tank. Especially towards the end of the flight when the tank empties and while performing aerobatic maneuvers.


In-flight fuel tank video from Oli Ni on Vimeo.


 In the video above, which demonstrate what happens to the fuel in the tank during aerobatics, the clunk is out of the fuel for 50% of the time, picking up air that will be sent to the air trap during this period.


1. Primarily, The air trap is here to buffer that amount of air and prevent it from entering the pump ( which would cause a flameout condition ). On this respect I strongly recommend fitting an air trap that volume equals to 30 seconds of consumption at full thrust.

2. The second function of a modern air trap is to protect the system against cavitation. For this, the fuel membrane must have two qualities: 

    a. Offer low restriction

    b. Being able to suck fuel even when largely uncovered and in the air

Our UFBK air traps excel in these two exercises. They uses the best plated paper filter membrane available on the market and super large fittings ( 3/16" , 1/4"  and 5/16" ID sizes or push-to-connect 6 mm, 8 mm, 10 mm or 12 mm fittings ). The membrane area is 4 times larger than most other air traps.

Additionally, the VaccuTest system featured on the 160 and 250 size allow you to monitor the "health" of your fuel system.


When the engine is set at full thrust, the pump will generate the maximum level of vacuum. This will pull the fuel level down.
As long as the level stay at or above the pocket bottom, the vacuum levels are low.
If the pocket empties completely, then the vacuum levels might be too high and a clogging condition might have occurred ( kink/ debris/ slime ) upstream the pump...
The pocket volumes are not random, but sized according to our experience for 160 N 250 N engines respectively. These only work when the air trap is set flat.

The 4 sizes will allow you to comply to the 30 seconds rule up to 1000 N engine class. The unmatched and proven quality of their membranes will get you the best resistance to cavitation on the market.

Technically speaking air trap consists of an aluminum screw type stopper CNC machined , a MIL spec kevlar tank and a bespoke super fine fuel filter membrane. 


Ultra large 12/ 10/ 8 and 6 mm MIL spec Pisco fittings can be specified on the 250, 500 and 1000  size and the air trap offers the option to have two supply lines for saddle tanks.


UFBK 250 with 6 mm push-to-connect fittings.

UFBK 250 with 8 mm push-to-connect fittings


Available sizes: 

160 for max 160 N thrust engines


250 for max 250 N thrust engines


500 for max 500 N thrust engines


1000 for max 1000 N thrust engines