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X-treme/Skymaster A-10 1/7.5 Build

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Old 01-19-2018, 08:49 AM
  #51  
Robzylla
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Hey Ravill how goes your build?
Rob
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Old 01-19-2018, 10:14 AM
  #52  
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Originally Posted by Robzylla View Post
Hey Ravill how goes your build?
Rob

Going pretty well actually. All things considered! I've been hanging out with my new son!

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Old 01-19-2018, 10:26 AM
  #53  
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I have both wings done, with lights, slats, gear doors, pylons and BVM Ultra Bandit gear all installed. All the servo extensions and air lines are plumbed!

As I want to have an idea of how much nose weight I'm going to need, I want to install the engines to get a sense of how I'm going to have to lay things out.

These new Kingtech K-85 G2's are beautiful and look like art!

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These engines are so compact, they fit all the way back in the nacelles and don't need pipes! I know I will pay a weight penalty to move them back, but to have the full thrust and a simpler install are appealing and I think, worth it.

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Then engine is also so compact that the engine rails skymaster included are too wide for the engine! I had to make new engine mounting formers.

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Old 01-19-2018, 10:28 AM
  #54  
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I added a light to the PAVE Penny pod. So cool!!!

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Old 01-20-2018, 08:57 AM
  #55  
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Looks Great! Interesting install on the K85. I will be watching to see how nose weight works out.
Thanks for update! And congrats on the "New" Guy!!!
Rob
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Old 01-20-2018, 11:00 AM
  #56  
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Be careful Rav, the thrust angle is critical on these A-10's
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Old 01-20-2018, 11:20 AM
  #57  
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Originally Posted by ravill View Post
Going pretty well actually. All things considered! I've been hanging out with my new son!

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Congrats Ravill
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Old 01-20-2018, 11:50 AM
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Originally Posted by Digital Pilot View Post
Be careful Rav, the thrust angle is critical on these A-10's
What is the thrust angle on this jet?
Is it close to the Mibo?

https://www.ultimate-jets.net/collec...-warthog-gen-5
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Old 01-23-2018, 12:40 AM
  #59  
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Originally Posted by Robzylla View Post
Looks Great! Interesting install on the K85. I will be watching to see how nose weight works out.
Thanks for update! And congrats on the "New" Guy!!!
Rob
Originally Posted by sergio turbo View Post
Congrats Ravill
Thank you!!

Originally Posted by Digital Pilot View Post
Be careful Rav, the thrust angle is critical on these A-10's
This has been made clear for sure!

I've set up the new engine mount formers to line up the exhaust of the turbines to be matched to the outlet of the nacelles.

Like this:

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I actually made SURE, that if in doubt, I wanted the exhaust to point a bit more up and out (towards wingtips).

There are countless stories of people trying to take off with their A-10's and as they try to abort the take off, the A-10's leap off the ground!

And trying to put the engines out at an 11 and 1 o'clock position (like bidrseed2 recommended).
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Old 01-23-2018, 12:03 PM
  #60  
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What is the purpose of pointing the engines outward?
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Old 01-23-2018, 07:03 PM
  #61  
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Inbuilt thrust vector so that if you lose an engine, the thrust pointing outward is compensating for the yaw induced by the Engine failure.
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Old 01-24-2018, 09:21 AM
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Thanks bidrseed2, that makes perfect sense. One more question regarding the down thrust from the nacelle, I notice you mentioned that you used a gyro which still couldn't fully compensate the pitch change from full power, so for people don't use a gyro, does that mean we need to hold considerate amount of elevator during take off or full power passes?

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Old 01-24-2018, 11:28 AM
  #63  
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Originally Posted by nerv View Post
Thanks bidrseed2, that makes perfect sense. One more question regarding the down thrust from the nacelle, I notice you mentioned that you used a gyro which still couldn't fully compensate the pitch change from full power, so for people don't use a gyro, does that mean we need to hold considerate amount of elevator during take off or full power passes?
Here is a complete answer to your question:

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When pointing the engines inward, you are trying to decrease the torque effects on the airplane, incase, of an engine out situation. Yes, you loose some forward thrust to gain some added safety if you have an engine out situation.

The engine to CG/Center of lift distance cannot be changed, so only the angle (and hence the Sine of that angle) can be changed to help ameliorate an engine out situation.

Now, with respect to the upward-rearward thrust, the REAL A-10 can stall the compressor blades when it pulls up hard after shooting some bad guys in tanks, so the Fairchild engineers had to face the nacelle intakes up, and add forward, inward slats to help smooth the flow of the air coming into the compressors so they don't stall.

In the second pic you can see that the nacelles point down and the horizontal stab is an up elevator position, this is again, to help with the real world A-10 bad a55ery flight maneuvers it has to do. (5's equal S's)

But for us modelers this is where we have these weird thrust angles to deal with and we have to try to figure the out as best we can (we ain't a skunk works! LOL) and well, we have to compromise as best we can.

If you are giving a lot of down elevator with lots of throttle, then you can bring the thrust angles down some, but this might compromise your low throttle flight characteristics as well. Regardless, the A-10 needs some upthrust to fly well.

I wasn't there when the A-10 was designed, this is just what I've gleaned from reading the inter webs, so it has to be true.Name:  smiley_driving.gif
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Old 01-25-2018, 10:12 AM
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Thanks for the detailed explanation Rav, and congrats to your new born I notice you live in Redwood city, which is not too far from me (I live in San Jose). Where do you usually go fly? I have the same jet with twin K60G and the angled thrust tube setup. I haven't maiden her yet because all the thrust angle story I read on internet lol I really like your engine installation, looks very clean and effective.
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Old 01-25-2018, 11:33 AM
  #65  
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I used to fly at Tomcats and Crows landing. Now there is a real club out there, but with LOTS of restrictions, so I joined, but still do bandito (ie just trespass) flying, especially with maidens.

And now, I mostly fly at Bayside (Fremont) And Hollister. I can’t wait for Tomcats to fix that darn road, I hate the driving around!
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Old 01-25-2018, 01:23 PM
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Oh, cool. I fly at the same places you fly lol Maybe we met at either TC or crows landing before, I know crows' schedules are weird and only on weekdays, but it works OK with me because my family takes all my weekends anyway....Well, definitely let me know when you decide to maiden your A10
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Old 01-26-2018, 02:12 PM
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Hey Ravill I am looking into more fuel cap. as well. How is your Jet Tech tanks fitting? May just call into to Gary and have set made.
Thanks!
Rob
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Old 01-26-2018, 04:40 PM
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How many more total ounces do you think you gained?
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Old 01-27-2018, 11:04 AM
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I would say I added 70-75 oz per side, so 140-150 oz total more.

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Old 01-27-2018, 11:04 AM
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Duplicate
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Old 01-27-2018, 11:09 AM
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Sent you a PM
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Old 01-27-2018, 11:23 AM
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I just joined Wavemasters in Hollister since Tomcats is close and probably will be close for another 2 more years before the County budgets the new bridge, really sucks. I already belong to the club at Crows but my work schedule got switched around and I now work Mon to Thurs, so I have no idea when I will fly at that club again. Raf let me know when you go fly and I'll bring my jets as well.

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Old 01-27-2018, 11:27 AM
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Leo! Whats up man!

Fremont isn't too bad either, but there are no taxi ways from the pits to the flight line really, so it's kind of a pain in the butt to walk your airplane over to the tarmac, but it's doable. I'm going to start bringing some jets out there. I'm tired of the driving around.

Hollister also can have a super annoying cross wind, I flew my Bandit a few times in that, and I was not having fun.
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Old 01-27-2018, 11:41 AM
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Hey Ravill I don't think my PM went. I am ordering tanks from Gary but he had a couple questions.
Can you give me a call?
Rob
619-301-3487
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Old 01-31-2018, 04:05 PM
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Originally Posted by ravill View Post
I would say I added 70-75 oz per side, so 140-150 oz total more.

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Hi Ravill,

Nice work on your A-10, I wish I have your build skills.

I have a question about your fuel tanks placement, I see in the manual that the tanks go over the wing tube, where the mid hatch is, in your placement, the tanks are before the wing tubes, isn't that going to generate CG problems?.

Thanks
Sergio

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