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Bob Cat Copy Falcon 120 Jet

Old 06-28-2010, 06:30 AM
  #3526
fireblade5437
 
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Default RE: Bob Cat Copy Falcon 120 Jet

Gregg

The Falcon is way more fun to fly than the intro... I just brought a P120SX perhaps just a bit too big for the Falcon

Alan
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Old 06-28-2010, 06:30 AM
  #3527
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Default RE: Bob Cat Copy Falcon 120 Jet

That was a good slot you watched. My dad was flying the falcon, and all 4 pilots know each other so decided to try formation with all 4. I've never seen it done with 4 jets before. I did the calling for the display and kept it pretty simple so as not to make it dangerous.

Too often at shows sport jets are just ragged round the sky separately. I think it worked and the pilots certainly enjoyed the challenge and extra pressure of not getting it out of shape!!

The falcon really does land at crawling pass as you obviously saw
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Old 06-28-2010, 06:36 AM
  #3528
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Default RE: Bob Cat Copy Falcon 120 Jet


Quote:
ORIGINAL: fireblade5437

Gregg

The Falcon is way more fun to fly than the intro... I just brought a P120SX perhaps just a bit too big for the Falcon

Alan

Err yes, just a tad.

we are still quite nervous of the falcon seeing as we had one of the original (short spa) ones. It just means we don't pull it to hard and fast in the turns although it does smooth out the flying when you think like that.

It's a lovely machine to fly and the performance with the wren is perfect
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Old 06-28-2010, 08:49 AM
  #3529
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Default RE: Bob Cat Copy Falcon 120 Jet

Yes it was very good, we have also just started doing some formation stuff with 2 intros and a harpoon just for fun, everyone loves to see them taking off and land landing at the same time, it is normally a panic at the last minute who is landing where, one will shout I'm on the left etc. good fun, just simple half cubans, rolls and loops look great when you do them together, and can really appreciate how good Steve and Matt are with their hawks.
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Old 06-28-2010, 08:56 AM
  #3530
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Default RE: Bob Cat Copy Falcon 120 Jet

Yes Matt and Steve are very good. Did you happen to see the flight where as they do the their opposition flat circuit and cross-over at the back, they didn't leave their normal height difference and went absolutely nose to nose! Thankfully they were at different distances but there is no way they could tell and their body language told a thousand words!!!

Formation flying is tough. I fly with the TJD warbird team so know how difficult it is.

Anyway, slightly off topic there.

Glad you enjoyed the show. We certainly did as a team and getting to fly dad's Falcon at the end was a nice bonus!
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Old 06-28-2010, 10:35 AM
  #3531
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Default RE: Bob Cat Copy Falcon 120 Jet

Thanks BaldEagle for the response.  I think that I will try the 0 degrees of thrust angle for my engine, but I don’t quite get why you do not need mixing with down elevator  in this configuration.  I sense that most people agree on the 330 mm for the balance point, so I am not sure how you do not need mixing, when others put in 5 degrees of up thrust to avoid mixing.  I also notice a on the page 140 that you discuss using reflex.  I have heard of this being done on gliders, but I have not tried it myself.  How much up do you recommend on the ailerons, and do you need elevator mixing with this.  I suspect you only use this configuration with full flaps.
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Old 06-28-2010, 10:43 AM
  #3532
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Default RE: Bob Cat Copy Falcon 120 Jet

The up thrust that is needed is because of the fast airflow under the tail which causes a negative pressure, but with a full tank the C of G is a long way forward even if you have the tank as far back as you can get it, the concequence of this is the need to re-trim during the flight as happens with all turbines without the tank directly over the C of G so I just re-trim during the flight as normal and it compensates for the lack of up thrust.

Reflex on the ailerons is only with 90deg flap, half flap no reflex, I use about 0.75" with a small amount of down elevator, only about 0.25", but it does put washout on the tips and helps prevent tip stalling when you come in sooooo slow as you can with this airframe.

Hope that helps.
Mike
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Old 06-28-2010, 10:47 AM
  #3533
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Default RE: Bob Cat Copy Falcon 120 Jet

Forgott, I used to have a mix on the throttle to elevator to compensate, but took it off as I found it was not as accurate as re-trimming, which you have to do to compensate for the fuel load.

Mike
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Old 07-02-2010, 06:12 PM
  #3534
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Default RE: Bob Cat Copy Falcon 120 Jet

Had 6 great flights today, on 6th flight, flying inverted downwind, elevator didnt feel right, maybe a drop out, but no response, or could have been the wind,which was a bit weird inbetween the rain showers and a full 90 degrees to runway, anyway rightway up, control seemed normal again, came round for immediate landing ( i was the only one at the flying site), rushed it and slowed up a bit too much and a bit short of the landing strip, accelerated, but too late and she pancaked in form around 15 feet. Entirely my fault, in fact its amazing she didnt tip stall. Ripped the gears out, booms have pulled through the wings, but engine is fine, fuse a bit buckled, looks like i need another. There was a link recently to a supplier in UK, selling them cheap, I think with a sort of white, red USA style paint scheme, if anyone has the link i would appreciate it. Oh well, she did me proud for around 120 flights, just my mistake. Cheers Tim
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Old 07-02-2010, 06:20 PM
  #3535
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Default RE: Bob Cat Copy Falcon 120 Jet

Hi Tim

Sorry about the 'landing'

The link I posted was CCRC Models but I do not know if he has them in stock at present, have a look on his web site.


[link]http://www.ccrcmodels.com/ic-planes.php[/link]

I just had a look it says available from mid july

Also if you click on the falcon it says £155.00 'in stock' I would give him a ring and ask!

Alan
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Old 07-03-2010, 03:34 AM
  #3536
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Default RE: Bob Cat Copy Falcon 120 Jet

Many thanks Alan, will give them a call. Looks like Colchester models are out of stock as well, obviously word has got around, cheers tim
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Old 07-03-2010, 04:31 AM
  #3537
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Default RE: Bob Cat Copy Falcon 120 Jet

Tim

There has been lots of disscusion on the Elan thread about the feeling of a woolly elevator, I don't know it this is unique to the boom and tail type of airframe, but I pankacked in my Elan the other day as well, and I have now come to the conclusion it was the woolly elevator that caused if and not the curvature of the earth and brian fade that I initially put it down too.

Mike
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Old 07-03-2010, 05:33 AM
  #3538
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Default RE: Bob Cat Copy Falcon 120 Jet

Hi Mike thanks for the info, elevator was wooly, then rolled over the right way up, and still seemed a little wooly. I put in a large up input then she suddenly nosed up, after that all was ok. After landing!, i checked all controls before touching anything. All controls were fine and elevtor was smooth and responsive. When i de-rigged, i loaded the elevator upwards with my hand and something jumped. Not sure if a spline on the arm or a gear. Will strip later to check. With elevator loaded downward, all was ok. I had flown in a sprited but smooth manner, over the past 6 flights, and the previous landing were some of the smoothest i had done. Tailplane was undamed and the inertia of the landing was unlikly to have caused damage to the servo gears
Was thinking previously of converting my old falcon into an F18 shape. Moving the wing up higher on the fuse and moulding into fuse with fairings. Using the existing wing spar mounts as pickups for two ply sides, which would mount the main spars and extend rearwards to carry the tailplnes and 2 fins. The engine would be mounted exactly the same, a simple ply plate, quick released to fit over the engine area between the tail fins, once engine started would improve rigidity of the back end. The bottom area of engine left the same, ie open. The mains would be fitted to the fuse and the wings might then produce a tad more lift with no u/c cutouts.
Thought of all moving tailplanes, the servo mounted in the tailplane, ahead of the pivot to produce a mass balance effect, and its output arm picking up on a ball link on fuse. Only thing is, static balance is not enough, dynamic imbalnce can produce massive loads on servos in flight.
Best i think to go for standard tailplains, same section as original and elevators. If i use same section and size, then model should fly similar, but wing might interfere with airflow over tail.
Any thoughts or suggestions welcome, im off for 3 weeks working away so cant do anything for a while, cheers tim
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Old 07-03-2010, 08:47 AM
  #3539
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Default RE: Bob Cat Copy Falcon 120 Jet

Found the problem, the elevator output arm on the servo has a hair line crack runing down the splined attachment hub. If i load the elevator it springs as the seratations open up and rise on top of eachother. It had not moved enough to jump a tooth, as i checked the controls on the ground and she looked like it is at neutral. That would explain the wooly control input. When i try to load the elevator the other way, the splines dig in tightly, with no spongyness at all. So when i rolled the right way up, the servo could then give me up elevator. Problem solved, at least i know what it was. Arms are the supplied nylon arms that came with the servos. The center screw was not overtightened and I NEVER use any form of thread lock on any servo screws, it eats the nylon gears. Mind you the servo has been in there for many years and acumulated in excess of around 250 flights, in boiling hot summer and freezing sub zero conditions, so cant complain tailplane is in perfect condition, 100 % undamaged. Now just have to improve my piloting skills again he he he. cheers tim
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Old 07-03-2010, 12:15 PM
  #3540
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Default RE: Bob Cat Copy Falcon 120 Jet

Good you found the problem Tim, lesson for all there I think about fast airframes and servo arms, just going to check all mine now, but I do tend to use the HD ones, but still worth checking.

Mike
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Old 07-03-2010, 10:09 PM
  #3541
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Default RE: Bob Cat Copy Falcon 120 Jet

where i can found the retract system for the Falcon 120 ?
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Old 07-04-2010, 02:55 AM
  #3542
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Default RE: Bob Cat Copy Falcon 120 Jet

Wing13Z, Digitech Turbines has a nice set. If you would like to order from them, let me know, as the shipping is steep, but it is not bad if we split the cost. Just sent me a PM or email. John.
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Old 07-04-2010, 10:59 AM
  #3543
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Default RE: Bob Cat Copy Falcon 120 Jet


Quote:
ORIGINAL: wing13z

where i can found the retract system for the Falcon 120 ?
Your local hobby shop either has, or can get Robart 560's with Robostruts (what I am using).
...or...if you want trailing links, Todd (at Dreamworks) has a set for it.

Good luck.
Greg
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Old 07-04-2010, 05:44 PM
  #3544
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Default RE: Bob Cat Copy Falcon 120 Jet

Tam Jets also has a set of trailing link. A guy in our club just bought a complete set of retracts, struts, wheels, brakes and air kit from Tam for the Falcon he is building. I saw it at the field. The retracts and struts were nice and beefy The wheels are an interesting light weight setup. The wheels have a hard inner rib with a foam tire laminated to either side to give it bulk and traction. Will see how they hold up...they are certainly light.
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Old 07-04-2010, 08:16 PM
  #3545
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Default RE: Bob Cat Copy Falcon 120 Jet

Guys, I have an almost complete set of the digitechs listed in the jet section.
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Old 07-05-2010, 06:06 AM
  #3546
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Default RE: Bob Cat Copy Falcon 120 Jet

I must admit that the Falcon has become my fav airplane lately. Just a lot of fun zooming around the patch.

My MW54 has been through a bad FOD incident (screw loose milled the LE of my impeller) but still works great!






[youtube]http://www.youtube.com/watch?v=HHCkX_LCqjs[/youtube]
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Old 07-05-2010, 07:32 AM
  #3547
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Default RE: Bob Cat Copy Falcon 120 Jet

Hi Erazz, some great flying there, getting in the groove, looked just like mine a few days ago. Your engine mount system looks agricultural in approach and obviously works well. Ref the compressor, they are really resilient to abuse, but obviously the balance might be an issue now. Usaually if out of balance, the engine noise changes and becomes loader, usually with a shrill. If out of balance it will impart a larger than normal load on the shaft and bearings and is not recomended.
Obviously you have much turbine experience, but would rather replace the compressor, not sure of price for yours, but the KKK2380 is around 85 pounds and easy to change, although again balancing is recommnended as the compressor wheel manufacturers balancing, which is done when the wheels are made, is not as accurate as the model jet engine manufactures tolerances. Anyway, some great flying what an awesom machine the falcon is. I am thiinking hard about modding my damaged falcon as stated previously, just to change its look into a more scalish fighter look, but retain the excellent flying and short field capabilities. I see some guys have gone tailless with their EDF conversions, now is a credit to those guys, experimenting with expensive kit, when anything could happen, full marks, cheers tim
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Old 07-05-2010, 07:59 AM
  #3548
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Default RE: Bob Cat Copy Falcon 120 Jet

I got a compressor for my wren 54 (12 blade) from Helptoday.co.uk a turbo charger spares place in the UK
it was only £42.88 incl postage, it is the Garratt 445347-0018 equivalent made by Turbo International in the USA part no. 3-A-3441.
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Old 07-05-2010, 08:43 AM
  #3549
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Default RE: Bob Cat Copy Falcon 120 Jet

Thanks Guys,

The replacement impeller is already on it's way but shipping is a pain!
I've rebalanced the impeller and it works a treat (no vibrations) and the power is the same.

I'm going with a bigger impeller to get more thrust. Possibly change the diffuser as well.
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Old 07-07-2010, 01:48 PM
  #3550
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Default RE: Bob Cat Copy Falcon 120 Jet

I don't see them now.
I guess they are sold.

How did you like the Digitech retracts in the Falcon. Are they really a drop-in fit? strut lengths correct etc?
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