Bob Cat Copy Falcon 120 Jet
03-13-2010, 01:35 PM
#3301
Junior Member
Join Date: Jan 2005
Location: Sao PauloSP, BRAZIL
Posts: 29
Likes: 0
Received 0 Likes
on
0 Posts
RE: Bob Cat Copy Falcon 120 Jet
Hi Dave,
Thanks for watching and for the tip.
You have a very accurate vision. You must be right, I need do add more down thrust. I have 6 degrees, but will change to 8 degrees. Thanks to remember me that. I was so anxious and with so much adrenalin that I forgot some plane behaviour to be corrected. It was my maiden on jets too.
Its CG is also behind the manual position. It´s 355 mm from leading edge with only UAT filled. I felt its elevator too sensitive.
Now it will go back to the bench and I will do the following changes:
1) More down thrust;
2) Bring CG forward to 330mm;
3) Install wheel brakes;
4) Change fuel tank from 2L to 1.5L coke pet. I flew 5 minutes with 2L pet and landed with a little more than half tank.
Thanks
Ricardo
Thanks for watching and for the tip.
You have a very accurate vision. You must be right, I need do add more down thrust. I have 6 degrees, but will change to 8 degrees. Thanks to remember me that. I was so anxious and with so much adrenalin that I forgot some plane behaviour to be corrected. It was my maiden on jets too.
Its CG is also behind the manual position. It´s 355 mm from leading edge with only UAT filled. I felt its elevator too sensitive.
Now it will go back to the bench and I will do the following changes:
1) More down thrust;
2) Bring CG forward to 330mm;
3) Install wheel brakes;
4) Change fuel tank from 2L to 1.5L coke pet. I flew 5 minutes with 2L pet and landed with a little more than half tank.
Thanks
Ricardo
03-13-2010, 03:25 PM
#3304
My Feedback: (48)
RE: Bob Cat Copy Falcon 120 Jet
Six degrees should be the right amount of down thrust for that engine. First, I suggest that you put the CG at 330 mm. and set your elevator trim for straight and level flight at your normal flying speed. Then adjust the down thrust if needed.
Joe
Joe
03-13-2010, 09:20 PM
#3305
Junior Member
Join Date: Jan 2005
Location: Sao PauloSP, BRAZIL
Posts: 29
Likes: 0
Received 0 Likes
on
0 Posts
RE: Bob Cat Copy Falcon 120 Jet
Thanks Sonnich Johannesen and Joe!
Joe,
I used 6 degrees based on your past posts. I followed many tips from you and have much confidence on your experience.
Dave noted a little up/down instability on my Falcon but he did not know I had a rear CG, so you may be right, it may be CG, may be down thrust or both things.
So I will do one change at a time, first CG and then down thrust if needed.
Your Red Bull FAlcon is a state of the art!
Ricardo
Joe,
I used 6 degrees based on your past posts. I followed many tips from you and have much confidence on your experience.
Dave noted a little up/down instability on my Falcon but he did not know I had a rear CG, so you may be right, it may be CG, may be down thrust or both things.
So I will do one change at a time, first CG and then down thrust if needed.
Your Red Bull FAlcon is a state of the art!
Ricardo
03-13-2010, 10:38 PM
#3307
Junior Member
Join Date: Jan 2005
Location: Sao PauloSP, BRAZIL
Posts: 29
Likes: 0
Received 0 Likes
on
0 Posts
RE: Bob Cat Copy Falcon 120 Jet
Hi, amigo Enrique!
Yes I did shut off the engine at landing. I did command a shut off after touching but, as turbine has a delay on shutting off, the engine only stopped middle past runway. I did that cause turbine´s idle was producing much thrust and the plane couldn´t stay stopped. Also did not have brakes. So, for safe, we decided to shut it on landing.
To try to solve that "problem" we lowered turbine idle rpm from 45000 rpm to 40000rpm, but it still couldn´t stay stopped. I did this with some fear, but the turbine was reliable all the time. I intend not to do that anymore and install brakes.
Abraço
Ricardo
Yes I did shut off the engine at landing. I did command a shut off after touching but, as turbine has a delay on shutting off, the engine only stopped middle past runway. I did that cause turbine´s idle was producing much thrust and the plane couldn´t stay stopped. Also did not have brakes. So, for safe, we decided to shut it on landing.
To try to solve that "problem" we lowered turbine idle rpm from 45000 rpm to 40000rpm, but it still couldn´t stay stopped. I did this with some fear, but the turbine was reliable all the time. I intend not to do that anymore and install brakes.
Abraço
Ricardo
03-13-2010, 11:00 PM
#3308
Join Date: Nov 2003
Location: Curitiba, Parana, BRAZIL
Posts: 4,289
Likes: 0
Received 14 Likes
on
11 Posts
RE: Bob Cat Copy Falcon 120 Jet
Yes, there is always residual thrust in any turbine so brakes are needed in jets, in both main wheels. You can use a simple on/off switch air valve with plenty of silicone grease on the wheel hubs for excelent results or a proportional jettronic type valve for smooth stops as well.
Again, congrats on your flight and specially for the landing without brakes!
Again, congrats on your flight and specially for the landing without brakes!
03-14-2010, 05:15 AM
#3309
RE: Bob Cat Copy Falcon 120 Jet
Lowering the turbine idle can result in a low speed compresser stall and flame out, it you need to do that again I suggest you put a mix on with your retract valve to keep the idle at the manufactures settings whilst in the air and having the lower idle only available on landing. Do remember to re-teach your ECU the new settings.
Mike
Mike
03-14-2010, 08:17 AM
#3310
Junior Member
Join Date: Jan 2005
Location: Sao PauloSP, BRAZIL
Posts: 29
Likes: 0
Received 0 Likes
on
0 Posts
RE: Bob Cat Copy Falcon 120 Jet
Thanks Enrique and Mike,
Your tips are really helpful. I will choose the cheapest brake system (on/off switch with grease on hub) and hope I will not need to low the idle anymore. If it´s still needed I will do as suggested by Mike, that´s a really good idea.
Ricardo
Your tips are really helpful. I will choose the cheapest brake system (on/off switch with grease on hub) and hope I will not need to low the idle anymore. If it´s still needed I will do as suggested by Mike, that´s a really good idea.
Ricardo
03-14-2010, 08:42 AM
#3311
My Feedback: (2)
Join Date: Jul 2003
Location: Brisbane, QLD, AUSTRALIA
Posts: 2,787
Likes: 0
Received 8 Likes
on
4 Posts
RE: Bob Cat Copy Falcon 120 Jet
Hey guy's
I have been working away at my Falcon120 and she is getting closer to being finished. I thoguht i better put someone in the office so here is my slapped together cockpit. I just made up some Vac from molds to keep the weight down. Not all that easy to see with such a tinted canopy but I need the nose weight so why not?
Thanks
dave
I have been working away at my Falcon120 and she is getting closer to being finished. I thoguht i better put someone in the office so here is my slapped together cockpit. I just made up some Vac from molds to keep the weight down. Not all that easy to see with such a tinted canopy but I need the nose weight so why not?
Thanks
dave
03-14-2010, 11:17 AM
#3312
Join Date: Nov 2003
Location: Curitiba, Parana, BRAZIL
Posts: 4,289
Likes: 0
Received 14 Likes
on
11 Posts
RE: Bob Cat Copy Falcon 120 Jet
Guys, I don´t think that is a good idea to use a low idle landing mix on a turbine plane. The residual thrust reduction will be very small and the spool up time and turbine reliability will be worsened at landing, when it is most needed in case of a go around. Worst case scenario would be a flameout, based on how difficult is for the turbine go from idle to full power specially in hot and humid conditions and at some altitude, like the one I presume Ricardo is flying (Sao Paulo).
I know it is a extreme example but interesting anyway: in carrier landings the pilots gives 100% of throttle just before touchdown in case he didn´t makes the wire so he can do a safe go around.
So I think that having a good pneumatic brake system, with grease or a smooth stop valve and a reliable spoolup idle is a better option for our models.
I know it is a extreme example but interesting anyway: in carrier landings the pilots gives 100% of throttle just before touchdown in case he didn´t makes the wire so he can do a safe go around.
So I think that having a good pneumatic brake system, with grease or a smooth stop valve and a reliable spoolup idle is a better option for our models.
03-14-2010, 11:38 AM
#3314
My Feedback: (48)
RE: Bob Cat Copy Falcon 120 Jet
Ricardo,
Looking at your video it doesn't appear that you're using a lot of flap. I use about 45 degrees, and some guys use more. By using the flaps as air brakes you need more throttle on your approach and you have very good control over your speed and decent. The plane is very stable and it is possible to come in and land at almost walking speed. Try more flap instead of lowering your idle speed.
Joe
Looking at your video it doesn't appear that you're using a lot of flap. I use about 45 degrees, and some guys use more. By using the flaps as air brakes you need more throttle on your approach and you have very good control over your speed and decent. The plane is very stable and it is possible to come in and land at almost walking speed. Try more flap instead of lowering your idle speed.
Joe
03-14-2010, 01:00 PM
#3315
RE: Bob Cat Copy Falcon 120 Jet
As I said it can lead to a low speed compressor stall and flame out, so not a good idea, just an idea to get over a problem, in fact I have my turbines set up the exact opposite i.e. higher idle with gear up, gives an amazing responce time with the 120SX I would go as far as saying as fast as any IC I have.
As Joe says use more flap, anything beyond 45 deg will act like an airbrake and will need higher throttle to keep flying, my flaps go to 90 deg and the control on landing is excellent, but then I have reflexed ailerons as well all controled on a side slider to give me something else to play with, first half of the slider gives me flap only up to about 45 deg and the second half gives me up to 90 deg of flap and about 30 deg of up aileron, fun on slow fly byes as the turbine is still in the upper range and once you put the flaps and things away the acceleration is instantainous, well it impreses me.
Mike
As Joe says use more flap, anything beyond 45 deg will act like an airbrake and will need higher throttle to keep flying, my flaps go to 90 deg and the control on landing is excellent, but then I have reflexed ailerons as well all controled on a side slider to give me something else to play with, first half of the slider gives me flap only up to about 45 deg and the second half gives me up to 90 deg of flap and about 30 deg of up aileron, fun on slow fly byes as the turbine is still in the upper range and once you put the flaps and things away the acceleration is instantainous, well it impreses me.
Mike
03-14-2010, 05:50 PM
#3316
My Feedback: (5)
Join Date: Nov 2004
Location: Boise, ID
Posts: 71
Likes: 0
Received 0 Likes
on
0 Posts
RE: Bob Cat Copy Falcon 120 Jet
Hey atomicx I bought one of these a while back. havent gotten to building it yet but i live in provo and would like to see what you did on yours if you dont mind. would you please drop me an email at [email protected]? thank you
03-14-2010, 07:38 PM
#3317
Join Date: Nov 2003
Location: Curitiba, Parana, BRAZIL
Posts: 4,289
Likes: 0
Received 14 Likes
on
11 Posts
RE: Bob Cat Copy Falcon 120 Jet
ORIGINAL: BaldEagel
As I said it can lead to a low speed compressor stall and flame out, so not a good idea, just an idea to get over a problem, in fact I have my turbines set up the exact opposite i.e. higher idle with gear up, gives an amazing responce time with the 120SX I would go as far as saying as fast as any IC I have.
As Joe says use more flap, anything beyond 45 deg will act like an airbrake and will need higher throttle to keep flying, my flaps go to 90 deg and the control on landing is excellent, but then I have reflexed ailerons as well all controled on a side slider to give me something else to play with, first half of the slider gives me flap only up to about 45 deg and the second half gives me up to 90 deg of flap and about 30 deg of up aileron, fun on slow fly byes as the turbine is still in the upper range and once you put the flaps and things away the acceleration is instantainous, well it impreses me.
Mike
As I said it can lead to a low speed compressor stall and flame out, so not a good idea, just an idea to get over a problem, in fact I have my turbines set up the exact opposite i.e. higher idle with gear up, gives an amazing responce time with the 120SX I would go as far as saying as fast as any IC I have.
As Joe says use more flap, anything beyond 45 deg will act like an airbrake and will need higher throttle to keep flying, my flaps go to 90 deg and the control on landing is excellent, but then I have reflexed ailerons as well all controled on a side slider to give me something else to play with, first half of the slider gives me flap only up to about 45 deg and the second half gives me up to 90 deg of flap and about 30 deg of up aileron, fun on slow fly byes as the turbine is still in the upper range and once you put the flaps and things away the acceleration is instantainous, well it impreses me.
Mike
03-14-2010, 10:01 PM
#3318
Junior Member
Join Date: Jan 2005
Location: Sao PauloSP, BRAZIL
Posts: 29
Likes: 0
Received 0 Likes
on
0 Posts
RE: Bob Cat Copy Falcon 120 Jet
I think I have 40 degrees or almost that.
I loved your flap configuration, Mike. I think I will copy it, if you don´t mind... just don´t know if mine can reach 90 degrees, but if I get 60/70 is also good in a crow mix. I will try.
Added to the right CG and a wheel brake system, it will be still better.
Dave, nice job on that cockpit. I had a rear CG issue on mine.
I installed everything less batteries more to the rear cause I thought it would need more weight on the tail. But that was a mistake in my falcon configuration. When it came time to measure CG to install batteries and switches, I could not reach the correct position even with 3 batteries near the nose, over the nose LG. So I had to move the pump and the UAT more to the front and only got CG at +/-350 mm. Now I will install brakes but its little extra weight wont correct CG, so I may unfortunately add some weight in the nose. Anyway it will still fly lighter cause I will change tank and save +/-500g of fuel weight.
Ricardo
I loved your flap configuration, Mike. I think I will copy it, if you don´t mind... just don´t know if mine can reach 90 degrees, but if I get 60/70 is also good in a crow mix. I will try.
Added to the right CG and a wheel brake system, it will be still better.
Dave, nice job on that cockpit. I had a rear CG issue on mine.
I installed everything less batteries more to the rear cause I thought it would need more weight on the tail. But that was a mistake in my falcon configuration. When it came time to measure CG to install batteries and switches, I could not reach the correct position even with 3 batteries near the nose, over the nose LG. So I had to move the pump and the UAT more to the front and only got CG at +/-350 mm. Now I will install brakes but its little extra weight wont correct CG, so I may unfortunately add some weight in the nose. Anyway it will still fly lighter cause I will change tank and save +/-500g of fuel weight.
Ricardo
03-15-2010, 04:16 AM
#3319
RE: Bob Cat Copy Falcon 120 Jet
Ricardo
On the flaps, the taper on the bottom side of the flap does not allow 90 deg flap movement as standard, however if you use the left flap on the right side and visa versa, turn them upside down and the straight edge of the underside of the flap allows 90 deg movement when installed with Robart pin hinges.
Mike
On the flaps, the taper on the bottom side of the flap does not allow 90 deg flap movement as standard, however if you use the left flap on the right side and visa versa, turn them upside down and the straight edge of the underside of the flap allows 90 deg movement when installed with Robart pin hinges.
Mike
03-15-2010, 04:17 AM
#3320
RE: Bob Cat Copy Falcon 120 Jet
Hey,
This thing is CRAZY!!! LOL, I had no idea how literally you guys meant "just pull on the bulkheads and they'll pop out..." How was this thing ever supposed to fly on glow power with the engine shaking everything?? It's amazing...
This thing is CRAZY!!! LOL, I had no idea how literally you guys meant "just pull on the bulkheads and they'll pop out..." How was this thing ever supposed to fly on glow power with the engine shaking everything?? It's amazing...
03-15-2010, 04:21 AM
#3321
RE: Bob Cat Copy Falcon 120 Jet
I don't think anyone on here was under any illusion that these things are made to a very low standard, but personnaly I think it was very good of the manufacturer to make it easy for use to remove the suspect parts. LOL
Just a heads up, when you install the UC in the wing, don't screw them on too tight, the bearers will fall out.
Mike
Just a heads up, when you install the UC in the wing, don't screw them on too tight, the bearers will fall out.
Mike
03-15-2010, 09:48 AM
#3322
Senior Member
My Feedback: (12)
Join Date: Apr 2008
Location: Carlsbad , NM
Posts: 1,319
Likes: 0
Received 0 Likes
on
0 Posts
RE: Bob Cat Copy Falcon 120 Jet
ORIGINAL: YellowAircraft
Hey,
This thing is CRAZY!!! LOL, I had no idea how literally you guys meant ''just pull on the bulkheads and they'll pop out...'' How was this thing ever supposed to fly on glow power with the engine shaking everything?? It's amazing...
Hey,
This thing is CRAZY!!! LOL, I had no idea how literally you guys meant ''just pull on the bulkheads and they'll pop out...'' How was this thing ever supposed to fly on glow power with the engine shaking everything?? It's amazing...
I looking for a carbon fiber wing spar. were do i get one.
