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Bob Cat Copy Falcon 120 Jet

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Old 10-05-2007, 11:17 AM
  #451
noahb
 
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Default RE: Bob Cat Copy Falcon 120 Jet

well you would not cut it without securing the small tube in the wing. Either with epoxy or hysol or something similar. Johnny has been flying his with a larger turbine, more fuel and has had no problems or at least has not reported any. If you look how it's secured in the wing, you will see that its being used as a anti rotation pin. It's not designed like the wing tube is.
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Old 10-05-2007, 11:20 AM
  #452
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Default RE: Bob Cat Copy Falcon 120 Jet

NOah get off the Computer and let go flying !!
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Old 10-05-2007, 11:57 AM
  #453
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Default RE: Bob Cat Copy Falcon 120 Jet

D'oh!
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Old 10-05-2007, 12:37 PM
  #454
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Default RE: Bob Cat Copy Falcon 120 Jet

Jascat,
Thanks for the reply about the sight gage. Great idea.

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Old 10-05-2007, 12:52 PM
  #455
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Default RE: Bob Cat Copy Falcon 120 Jet

If it was to be just a anti rotation pin,it would be like the trailing edge locator dowel pins.You guys did install those,didn't you?Anti rotation pins don't extend into the wing 5" or more.I think this particular pin serves two things and cutting it in half eliminates one purpose.Don't you think a anti rotation pin would just be a 1/4" dowel rod like the rear ones?
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Old 10-05-2007, 02:31 PM
  #456
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Default RE: Bob Cat Copy Falcon 120 Jet

Then leave it in. For those that already know that it will be fine to trim it, then they can trim it. Either way, it works just fine.
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Old 10-05-2007, 02:38 PM
  #457
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Default RE: Bob Cat Copy Falcon 120 Jet

trimming it and using it as an anti rotation pin is a good idea to get more room, i wonder about the hurt in structural integrity though - definitely a topic worth investigating !
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Old 10-05-2007, 03:15 PM
  #458
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Default RE: Bob Cat Copy Falcon 120 Jet

A continuos beam across the fuselage can carry far more bending moment than the two stubs. That is not in dispute. What is in dispute is if the Falcon 120 needs the added capability or not.
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Old 10-05-2007, 03:26 PM
  #459
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Default RE: Bob Cat Copy Falcon 120 Jet

Exactly !
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Old 10-05-2007, 03:29 PM
  #460
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Default RE: Bob Cat Copy Falcon 120 Jet

Well, if you would look inside the wing where it attaches, you will see that it's not in there for any bending movement as noted. Johnny flys one that has a bigger turbine and more fuel then most are using. He has done this and it has worked out great. If you are looking for more fuel room, then trim it. If not, then don't. Either way, I believe it will be ok. This is my opinion only. Enjoy.
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Old 10-05-2007, 03:36 PM
  #461
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Default RE: Bob Cat Copy Falcon 120 Jet

I would not say that AT ALL! I just went out to the garage and took a look in the wing. I assume the wing holes of which you speak are the forward-most ones, right? If so, there is a cardboard tube that does indeed run from the wing root out to the next rib. The couple created by those two ribs can carry substantial moment. True, not as much as the main spar, but that does not mean that you don't need it! Johnny may just be lucky, so far. Maybe not!
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Old 10-05-2007, 03:45 PM
  #462
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Default RE: Bob Cat Copy Falcon 120 Jet

I agre that it is needed. What I believe is not needed is for it to be joined to the other wing. I think if like was stated earlier to trim it so that it will only stick in the fuse say a 1/4" or so, that it would be good. I would not fly without it in there. I just don't think that it has to be joined to the other wing. It would have to be glued in place to prevent it from coming out.
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Old 10-05-2007, 04:01 PM
  #463
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Default RE: Bob Cat Copy Falcon 120 Jet

You may be correct, you may not be. If it is not continuos across the fuselage, then it can only react shear in the Z direction. If it is continuos, then it can react Z shear and an Mx bending moment. It is unknown at this time if you need it to be capable of recting the Mx bending moment. Perhaps the main spar can react all of the Mx you need. If you don't need it, you are fine. If you do need it (like if Johnny has been very lucky), then you might have a very bad day due to eliminating the center spar portion. I would try and find a solution where you can leave it intact for a warm, fuzzy peace-of-mind feeling.
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Old 10-05-2007, 04:03 PM
  #464
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Default RE: Bob Cat Copy Falcon 120 Jet

PS. The fact that they put the tube in there to carry shear out to the second rib suggests that someone thought they would need the moment capability. Perhaps they knew more than us?!? Perhaps they just wanted to waste some Chinese guys building time.
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Old 10-05-2007, 04:15 PM
  #465
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Default RE: Bob Cat Copy Falcon 120 Jet

That could be true. I guess each will do with what they are comfortable with. In my opinion, if they truly were concerned about the strength of the jet, they would have done a much better job of building the wings and fuse formers, and glue. I would worry more about the glue inside the wing, then the front tube. However, it comes down to what you will be doing to the jet (flight wise) and also what you are comfortable with. cheers
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Old 10-05-2007, 05:39 PM
  #466
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Default RE: Bob Cat Copy Falcon 120 Jet


Quote:
ORIGINAL: Jet Lag

If it was to be just a anti rotation pin,it would be like the trailing edge locator dowel pins.You guys did install those,didn't you?

What dowel pins! I didn't get any?

BiGToP
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Old 10-05-2007, 06:29 PM
  #467
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Default RE: Bob Cat Copy Falcon 120 Jet

Big Top,look at the trailing edge area of the wing and fuse and you will see a liittle indentation where you were to drill a hole for the dowels.This keeps the inboard trailing edge of the wing aligned to the fuse.Use a 1/4" dowel rod a cut yourself a couple.
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Old 10-05-2007, 06:50 PM
  #468
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Default RE: Bob Cat Copy Falcon 120 Jet

Ok thanx Jet Lag
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Old 10-05-2007, 09:14 PM
  #469
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Default RE: Bob Cat Copy Falcon 120 Jet

Guys
I have jumped in too. I just got my Falcon 120 and plan on putting an MW54 on it. I have been following this thread and the info I am getting here is going to be very helpful. On the subject of the front aluminium tube, remember one very important thing. This plane was designed to fly with a 120 size prop motor. Speeds of approx 60 to 70 MPH at most. With the turbines we are putting on them we are probably going to be upwards of 130 plus. Take it as you will.
I do have one question concerning the landing gear.

Has anyone taken into account the lenght on the struts? The way I see it this length was designed to clear a 14-16 inch prop. I was thinking about shorting the struts and cutting new wheel wells out. I like to get some thoughts on this idea from the guys flying.
Also what kind of finished weight are these planes coming in at?

Thanks
Joe Lewis


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Keep the sky between your plane and the ground!
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Old 10-06-2007, 05:28 AM
  #470
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Default RE: Bob Cat Copy Falcon 120 Jet

Guys,

here is the 1.9L tank we found, together with the original Falcon 120 fuel tank (0.5L) - and as you can see we could easily insert another Falcon tank (0.5L) inside the fuse, for a total of 3L and a bit with the UAT.

Or use one of them (or 2) for smoke...
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Old 10-06-2007, 02:47 PM
  #471
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Default RE: Bob Cat Copy Falcon 120 Jet

Joe,Mine comes in at 14 Ilbs with the UAT full.I did not use shorter gear,but after bending the mains a few times on landings,I need to rethink the gear issue.If your using air up,spring down on the nose,I would redo nose mount so retract will retract forward and spring down to the rear so it will lock when you lower the gear.With air up and down,this wouldn't matter,Ck with Jim Hiller,he got some stick time on mine last weekend.I have a T-500 for power and a Dubro 50 oz tank pushed back almost to main spar.Its definately nose heavy on take off because of the fuel load,but doesn't seem to effect the flying at all except for a little down elevator when inverted. Gerry
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Old 10-06-2007, 02:49 PM
  #472
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Default RE: Bob Cat Copy Falcon 120 Jet

any of you guys know anyone who has fitted a P70 in one of these?....just picked one up the other day from colchester models here in the UK...P70 is the smallest turbine i have......

cheers
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Old 10-07-2007, 05:54 AM
  #473
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Default RE: Bob Cat Copy Falcon 120 Jet

THESCALEMAN, my friend is building one with a P70 as we speak, will take a few weeks to finish though.
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Old 10-07-2007, 03:01 PM
  #474
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Default RE: Bob Cat Copy Falcon 120 Jet

Hi guys, did a post two days ago, with pics of the tank install (Persil Bottle), but website crashed and it was lost.
Had 6 flights yesterday, had three flame outs, and three normal landings.
The Persil bottle holds 1600 mls not 1700 mls, I qouted before. Cg is better, with the Persil tank full, it requires only 150 gms on tailplane to balance, as opposed to the 2 litre pop bottle with 1700mls of fuel, at 275 mls.
This reduction of fwd shift of the cg , was slightly noticable on take off and was a little noticable in flight, straight after take off and in a turn.
My Jet 1A nose leg (big Boomerang leg not the Intro) performed brilliantly. Had to machine about 10mm off the top of leg, to give me 145mm from top of leg to the axel center. I fitted a RipmaxF-RMX3070 70 mm wheel, which has performed well and at around 6 pounds for two, is excellent value. Wheel is still completely true.. I think this is the part number, as the wheels were packaged wrongly. I fitted a quick make shift spring clip to hold the nose leg centered during retraction, secured with sellotape, it worked perfectly. The nose gear bay plastic moulding, I cut out to allow the 2.75 inch wheel to retract right up into the fuse, so leg goes up 90 degrees. I used the plastic moulded packaging the wheels came in, to form an additional space for the wheel to fit up into, again just sellotaped into position. The nose sticks better to the ground during take off and taxi, and on landing, the model just sits down. The AT main legs performed brilliantly again. I think after my 10 flights and taxiing around, the original gear would have damaged the wing and fuselarge mounts.
I will post up some video of some take offs and landings so you can see how good they are.
After the 3 flame outs, I must say the plane glides beautifully and 2 landings were performed off the landing strip with gear up but no damage at all. Still have to work out the cause of the shut downs, but fuel feed was not the problem, not one air bubble anywhere and UAT was BubbleLess.
With 6.5 mins of flight and taxi back, I still have around 1/2 inch of fuel in tank, will measure how much tomorrow.
Tried a take off with 20mm flap, did not notice any improvement in take off performance.
Airframe is around 14.5 pounds Dry but with full UAT, and fuel and fuel tank weigh 3 lbs 1/2 oz. Engine ( home made) thrust around 12.5 to 13 lbs Tim

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Old 10-07-2007, 03:03 PM
  #475
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Default RE: Bob Cat Copy Falcon 120 Jet

how's he going to fit the engine...mount wise?...has he figured any thing out yet......the jetcat mount is too big......fitted the servos in the wings today.....will use a 2ltr pop bottle for the tank...that will go in tomorrow night.....not fitting retracts...just fixed legs...flying off grass.....haven't had much luck with my other jets off grass and retracts....

post some pictures nearer completion

cheers

dave
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