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Thunder Tiger 35% Extra 260 Build Blog


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Posted by john stones 1 on 25/03/2017 20:44:04:

Yep it flew very nicely, most impressive thing was the noise or lack of it,cans totally change the tone of the noise as well as quieten, petrol models lose flying sites ? no they don't.

Wants some Decals on now especially on the rudder wink

John

I wasn't going to mention your strimming skills - oops I just did.

Don't know whether you noticed but It has some strategically placed "PowerBox" stickers covering the entry and exit holes on the rudder.

gary.jpg

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  • 2 weeks later...

One little issue I noticed is that the silencers have slid backwards by about 5mm - resulting in them rubbing on the cowl silicone edge strips.

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Everything is still secure inside. It looks like the PTFE tube has slid along the header pipe. This is something I feared might happen and I touched on it earlier in this thread.

One solution would be to realign things then drill through PTFE tube / header pipe and screw a self tapper in.

This is a bit drastic, so I'll try something else first......

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0.9mm control wire and silicone fuel tube - anchored around the edge of the engine box and the engine stand-offs.

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Alignment OK for now. I'll monitor this.

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While I had the cowl off, I did something I should have done initially - cut a hole for accessing the carburettor needles.

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Hole plugged with a closed grommet.

Ready to try out again tomorrow.

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The movement of the PTFE joiners is a common issue and I think your cable and silicone tube is not the best solution, for years now I've drilled through the joiner and manifold through the gap in the spring clip and inserted a short self tapping screw with a suitable washer, and never had a problem since. Red X marks the spot where I would drill

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Posted by Rich2 on 07/04/2017 19:27:13:

That will probably work ok, my thought was to put a "stop" at the rear end of the canisters..

I never thought of putting something at the rear end to stop the silencers moving. Might be tricky because the tunnel exit is angled downwards.

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Posted by Ultymate on 07/04/2017 19:57:12:

The movement of the PTFE joiners is a common issue and I think your cable and silicone tube is not the best solution, for years now I've drilled through the joiner and manifold through the gap in the spring clip and inserted a short self tapping screw with a suitable washer, and never had a problem since. Red X marks the spot where I would drill

 

Thanks for this post Ultymate!

My guts were telling me that self tappers was the way to go. I never considered the natural "V" in the spring though. Sounds like a great idea!

Do you also put one through the silencer end of the joint?

I went for the wires because it is 100% reversible. I'm not convinced it will work but it's worth a try

Edited By Gary Manuel on 07/04/2017 20:34:23

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In my experience it's never been the Canisters that move as usually they have a barbed or etched marking on the mating surface, however if you want to go the belt and braces route you could always do both ends

 

Edited By Ultymate on 07/04/2017 20:45:02

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Thanks UM.

Yes the silencer is barbed.

Also of note, when I put the plumbers grips onto the joint and turned, it was the header end that moved first on both sides. Although the silencer protrudes less into to the joint than the header, it has far more grip - thanks to the barbed surface. If wires fail (or I get the time / inclination), I'll have a go with a self tapper through the "V".

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Gary, when I first ran my krumscheid tuned pipe on my Inverza 62 mark 2 recently, I literally blew the pipe off the manifold! In the end I fitted two metal brackets that gripped the pipe at intervals which stopped the movement. I also fitted smaller spring clips on the joiner and that problem has been solved.

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I flew the Extra several times at the weekend. The wires appear to have held the silencers on, but I'll keep monitoring the situation and fit self tappers if it ever moves.

One little problem I did have is that the tail wheel lost it's tire at some point. The tire must have actually split in 2 as that is the only way it could break free from the wheel / brackets, which would have held an intact tire captive.

I suspect that the cause of this was that the tail wheel was turning too much when rudder was applied while taxiing, causing the tyre to be ripped off the side of the wheel. Rudder stick at half way would apply full lock to the steerable wheel. Any further rudder movement was taken up by the springs.

The excess movement of the tailwheel was because the control arm was relatively short compared to the rudder control arm. I have now made a longer control arm for the tail wheel which is roughly the same length as the rudder control arms.

This photo shows the new arm fitted, compared with the old one.

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This photo shows the rudder (top of picture) at full throw with the tail wheel turned at roughly the same angle.

It also shows that the tail wheel tire would need to split in half to escape.

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Edited By Gary Manuel on 10/04/2017 16:37:46

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  • 6 months later...

Hi Gary, just been reading your thread again as I need to do some research for a build. The micro matches look good, did you add anything else to the system, powerbox, etc?

I need 2 servos per wing, 2 rudder and 2 elevator. I am thinking of using 4 micro matches units.

I was considering this XPS24: **LINK**

The main advantage seems to be the servo matching is made simple. But you still need to do something about all the wiring - you don't want all the servos going back directly to the receiver? I did think of using the Futaba sbus.

This is all new to me crook

 

Cheers

Rich

ps in hindsight I should have used the micro matches in my Yak's, it would have made the twin servo elevator setup much easier

Edited By Rich too on 20/10/2017 08:32:35

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Hi Rich.

I didn't use a powerbox unit but I did use the JR Powersafe RD922, which I already had at the start of my build. This is not a receiver as such, but more a battery redundancy system and high power connection point for all 9 servos. It uses 3 (or 4) plug-in satellite receivers.

As you know, I used 3 Powerbox micro matches to provide me with the additional 3 servo drives I needed as well as a means of balancing the servo outputs. These are great, but obviously the more of them you use, the more the cost adds up. You will eventually reach the point where it's cheaper to buy a full Powerbox system or similar. As you have noted, they do have the advantage of reducing the number of servo wires running back to the receiver. My wings for example only have one servo connection to connect to the fuselage.

I'm not familiar with the Xtreme Power Systems X24 you are thinking of using, but it looks to be similar to Powerbox systems, which I've also never used.

P.S. You shouldn't need a micro match for the two elevator halves if you have enough channels on your transmitter / receiver - just allocate one channel per elevator half and use sub trims / travel adjust to balance them.

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Thanks Gary. I have read conflicting arguments over whether standard receivers can handle the power of multiple high power servos. And I was thinking of using my standard servo and 4 micro matches... presumably these units are unable to match the servos automatically throughout the range of movement?

I currently use ch 2 and 5 (Futaba 7c) for split elevators and find it a pita to set up. the micro match sounds better.

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Careful Rich.

Micro matches don't have their own power supply - they take the current for both servos from the receiver. Think of them as a glorified Y-Lead with the ability to reverse the direction and / or match the centre and endpoints of the servo outputs. The receiver therefore needs to be up to the job of driving ALL the servos - hence why I used the JR922, which has a 35 amp continuous / 50 amp peak current rating. Powerbox / Xtreme XPS24 perform similar functions but are also able to reverse / match the outputs directly (I think).

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  • 4 years later...

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