FOD screen
 

I really need a proper FOD screen on my J600. I have a home made screen but it isn't sealed to the engine case at the back of the screen and I have noticed that two compressor blades have tiny impact chips on their leading edge. Is PST not going to make a proper FOD screen, and if not is their a screen from another brand that fits properly?

Harry

RE: FOD screen
 

Harry,

Todd at Dreamworks RC http://www.dreamworksrc.com

has one advertised for a JetCat P70 that fits my PSTJ600R perfectly.

You could also try putting a little Silicone RTV between the homemade screen and the turbine housing. I did this on the PST in my Boomerang Intro and it works fine.

RE: FOD screen
 

Over-sized FOD screen should give adequate protection if it enclosed the engine front. We don't recommend a silicone sealant as this can come loose overtime and will be sucked into the engine. On my engine, I don't seal the back of the FOD screen against the engine cover. I use FOD screen that is about 1-2 cm larger than the engine diameter and just let it sits centered over the starter. When the turbine is running, the suction will pull the screen tight against the engine cover.

Keep it simple and make sure that the mesh is not too fine. Remember that if you reduce the intake air volume, you will raise the EGT and decrease the thrust output. :eek:

RE: FOD screen
 

Made a FOD from a tea strainer, $1.00 at "Dollar General", fitted another make turbine perfectly, 3.75" O.D. . I also worried about the reduction in air due to the mesh, so decided to measure.
The mesh wire is .006, the mesh centers are .032, calculating shows a 67% air to mesh ratio.
The total available surface area of the mesh is 16 Sq in, take away the area of the starter and you are left with approx 15 sq in.
The available air entry is 15 x .67 =10 sq in . The area of the the compressor is approx 3.14 sq in.
So is the 3:1 ratio sufficient?
Thanks
Bob

RE: FOD screen
 

You forgot the turbulence that round makes in airflow.
Darryl

RE: FOD screen
 

Darryl, OK, so whats the answer?
Regards
Bob

RE: FOD screen
 

Do not know, but real ones ice up with the right conditions.
Darryl

RE: FOD screen
 

Bob,

Your calculation is correct for area ratio. However, the intake and compressor designs assume zero restriction or infinite area ratio to the surrounding. If we take this as 100% air volume available at the intake to the compressor, then any restriction you placed in front of the intake will reduce the air volume accordingly. From your information, you are restricting or reducing the intake air volume by 33%. What this means is that you are reducing the intake area by 33% and this will have direct effect to increased EGT and reduced thrust output. From experiment, an average FOD screen with 25% restriction will reduce thrust by about 10-15%. With higher restriction, engine ramping is also affected and you may experience hesitation or flaming during acceleration if ramping value is not changed.

Regards,
Kraivuth S.
PST Jets

RE: FOD screen
 

Kraivuth S. , many thanks, great info.
So whats the optimum FOD, we have got to have something, right?
Regards
Bob

RE: FOD screen
 

I would use FOD screen with 25% restriction or less. Sink drain filter works best. Tea strainer is too fine. I find these sink filter at kitchen or plumbing accessories section.

Have fun,
Kraivuth S.

RE: FOD screen
 

I would like someone to answer HarryC's question. Is PST going to provide/manufacture a FOD screen for the 600R?

I looked at the screens provided by Dreamworks and there were none for the P70. They advertise screens for the P80 and up.

I've looked for a sink screen and can't seem to find one that meets the expert's criteria. I think there is a market for a screen for the 600R, I'll buy one if somebody decides to make them.

Speedbrake

RE: FOD screen
 

PST Jets will produce the FOD screen for J600R and J1300R. Production takes time so I did a quick search on the internet and this is a sample of filters that can be used. They usually come in 60,70,90, and 110 mm sizes. 90mm is perfect for J600R while 110mm will fit the J1300R.

http://www.wholesalecentral.com/eagl...6catid%3D69077

Regards,
Kraivuth S.

RE: FOD screen
 

Hi speedbrake!

Go for Tamjets FOD guard for a P-60. We use one on the J-600R in the reaction R54 and it a) works great, b) does look professional and c) ain't that expansive compared to a new compressor and/or turbien wheel. It comes with a big O-Ring to hold it on the starter. Both ends are "framed" and they provide short pieces of 3/4mm tube and two Festo-connectors.

Best regards,

David

RE: FOD screen
 

We now have FOD screen available for both J600R and J1300R. We are at the Top Gun 2007 in Florida and I will post the price and pictures here asap.

Cheers,
Kraivuth S.