Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

High Performance Servos - 150mph+

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Old 09-20-2003, 10:03 PM
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RPZ
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Default High Performance Servos - 150mph+

Hey Guys - Lookin' for some free advice here...

I have a Patriot on the board right now - building for all-out speed. It'll have a Jett FIRE .60 on the nose, robart air retracts, no scoops, fully faired hinges, flaps, dual aileron servos, ... anything that will make it go fast.

I am wondering just how much torque I will need in the servos for the elevators, rudder and ailerons. I have cut the ailerons down from full length to approx 60% of plan. The remaining inboard control surface makes up the flaps (using the stock aileron servo location). Each aileron has a dedicated servo that will only need approx. 4" of pushrod.

Elevator and rudder are stock.

Do I really need to go to 90oz.+ in the ailerons? or will 50oz. each be sufficient? how about the elevator? I don't think I'll be using the rudder too much at the top end. Also, with the faired hinges, flutter should be all but impossible(??). Any comments are welcome.

Cheers!
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Old 09-20-2003, 11:54 PM
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Razor-RCU
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Default RE: High Performance Servos - 150mph+

Cool! I just posted on another thread about the Patriot...(love this plane-)

I have mine set-up with a Jett-50, Split flaps, Spring Air retracts and an APC 9x9 and I run STANDARD SERVOS (OnE for BOTH ailerons {bellcranks} one for flaps)

I run 6V and that pushes my STD servos toward 60 oz. torque- Granted you have a bigger jetT in there... Since you have one for each and the rods are close to the surface, you could probably get away with STD's on 6V- But.... why risk it?

I have some low profile aileron servos (Different plane-) that are 77 oz.@ 4.8 which were not very expensive...

Also, I use the rudder quite a bit because the Patriot does a great knife-edge and it also helps with hesitation rolls-
Anyhow good luck and keep us posted-

Jett-60.... Geesh, should be AWESOME!
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Old 09-21-2003, 08:11 AM
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daven
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Default RE: High Performance Servos - 150mph+

Correct me if I'm wrong, but I believe the Jett .60 utilizes the same engine case as the Jett .90. In my opinion, if your going to use the .60, you might as well get the .90. As to servos, I wouldn't skimp to much. I would definately look at something over 70 oz.
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Old 09-21-2003, 11:37 AM
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Default RE: High Performance Servos - 150mph+

Interesting thought... I just looked up the Jett specs for the Jett FIRE - seems the 90 is quite a bit larger all around. Also quite a bit heavier. The interesting thing about the 60L is that it has exactly the same mounting dimensions and cowl requirements as the OS .46FX, which is what the Patriot calls for. This is really interesting for my purposes. One of the other things I am looking into is the ratio - keeping the linkages close to the servo centre, rather than out on the edge, short links where possible, and upsizing the battery system to provide 6V (Good idea Razor). What I am thinking about right now is a compliment od JR 537 ball bearing servos for each aileron, the rudder and elevator, anlong with a 507 standard servo for the flaps. There would also be a mini servo running the valve for the retracts and another mini on the throttle.

Cheers,

Randy
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Old 09-21-2003, 12:23 PM
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Razor-RCU
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Default RE: High Performance Servos - 150mph+

Sounds good! You gonna move up the thr. servo?

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Old 09-21-2003, 12:43 PM
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Default RE: High Performance Servos - 150mph+

What I am thinking about right now is a compliment od JR 537 ball bearing servos for each aileron, the rudder and elevator, anlong with a 507 standard servo for
Since your going for speed, you have to couple the servos to take advantage of whatever torque. You would want holding power so digitals should be considered.

Just my opinion.
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Old 09-21-2003, 01:35 PM
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Default RE: High Performance Servos - 150mph+

don't forget about centering precsion. That last thing I want at 150mph is servos that don't center very well.
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Old 09-21-2003, 08:04 PM
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Default RE: High Performance Servos - 150mph+

ORIGINAL: Razor-RCU

Sounds good! You gonna move up the thr. servo?

Razor - I am thinking about moving it, but depending on the air canister and dual gyros that will be in it I will have to play that one by ear. The linkage will be a cable anyway, so routing will be easier. I also plan on using the false cockpit to mount the indicators, such as battery gague, air pressure fitting, air pressure gague, etc.
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Old 09-21-2003, 09:44 PM
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Default RE: High Performance Servos - 150mph+

Dual gyros? Do you think it will need them?

Sounds like it is gonna get heavy-
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Old 09-21-2003, 09:47 PM
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ChuckAuger
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Default RE: High Performance Servos - 150mph+

I cannot imagine needing any Gyros in a Patriot....much less 2..
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Old 09-21-2003, 10:05 PM
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RPZ
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Default RE: High Performance Servos - 150mph+

The second gyro was to be intended for the ailerons - at the top end, it's not required. Take-offs and landings are another. The first is on the nose wheel for takeoffs. If the plane is solid enough, I may eliminate one or both of them. My experience with the GP LearJet showed me just how impressive a gyro can be. Weight-wise, they are pretty good. I am pretty concerned with weight overall - thus the choice of the Jett FIRE 60 - but I am willing to compromise on the gyros if it makes the difference that it does on the LearJet. Hopefully, the Patriot is not as squirelly as the Lear - that would be a good thing, but there are a lot of structural similarities on the two models.
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Old 09-29-2003, 01:11 AM
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Default RE: High Performance Servos - 150mph+

Th nose-wheel is WAY in front of the mains-

I just haphazzardly (SP?) gun my Pat with the Jett-50 and it tracks better than a trainer-(just use EXPO. on the rudder/ nosewheel to make it less sensitive around center stick-)

I have spun the tire off the actual rim on take-off though... pretty interesting!

I am still amazed you folks are putting bigger JETT's in a Patriot(s)- Someone needs to upscale a Patriot to .60 size so we can stuff an OS-91VRDF in one-

Keep us posted!
james
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