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KMP F-7F Tigercat

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Old 01-06-2013, 08:59 AM
  #2051
rc4j
 
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Default RE: KMP F-7F Tigercat

I've got an all composite ARF that I've yet to start, and I'm also undecided about which power plants to use. I've got a pair of laser 150's which I know will do fine, however I'm not too sure I want to go glow. I have one 3W-24 but the fit isn't the greatest, as it would need a custom prop drive extension made, to put the cylinder head cutout at a reasonable location behind the curve of the cowl. I've also considered a pair of Zenoah 20's, as a lot of folks have used with good results, and also pondered the 26's for a little more oomph.

Here is a video on youtube, that you may have seen, where 3 TC's are flying together. Engines are O.S. 1.20 , Laser 1.50 , and Zenoah G20.


[link]http://youtu.be/0fEgjyFcRjs[/link]

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Old 01-06-2013, 09:54 AM
  #2052
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Default RE: KMP F-7F Tigercat

Quote:
Either engine choice will be fine, My first one had G-20's and pulled good. I'm finishing my second one with G-26's. If I had it to do all over, I would have used big 4 stroke glow due to being a lighter setup. Keep the model as light as you can.
Thanks RCnut101. Now I will go back through the thread and see which 4 stroke glow has worked well. I was thinking about fuel costs, but considering the $ I will have in this plane, that seems kind of insignificant. My biggest concern is reliability. I've flown glow twins before, but never gas, and my impression from reading threads here, and at my flying field, seem to suggest gas might be better in this regard? Whatever I go with, I plan to fly it on another plane as a single until I really get to know it.
Don
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Old 01-06-2013, 10:04 AM
  #2053
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Default RE: KMP F-7F Tigercat

Hey, I already have two MOKI 2.10 two strokes. I wonder if anyone has tried those? Talk about burning up glow fuel! They run and sound great but are very thirsty.
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Old 01-06-2013, 05:01 PM
  #2054
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Default RE: KMP F-7F Tigercat

Hi Don - I think you may have fuel problems mainly not having enough room to put in large enough fuel tanks for glo fuel. I'm running Gasoline engines (Fuji 23s - 1.5cu. in.) I sure like the safety of plenty of air time for Go-Arounds when things don't work out. I have been at Air Shows and panic situations arise with other pilots and I just Fly Around. I can fly easily for 20 minutes on 24 oz tanks. I also like the safety of Go-Arounds when I don't make a good approach. Pic. F-86D (1955) Col. Chuck Winter
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Old 01-07-2013, 04:54 AM
  #2055
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Default RE: KMP F-7F Tigercat

Thanks Col. Winters, Gas it will be! I hadn't considered the fuel tank issue yet, and you are correct I would have to haul around bigger tanks for less flying time. I have enjoyed reading your many posts, all the photos and videos. This is invaluable for newbies like me.
Nice photo of you and the F-86.

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Old 01-07-2013, 09:30 AM
  #2056
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Default RE: KMP F-7F Tigercat

ysolomon,Just received my F7F,will be going electric also.Probably wont start till late summer.Had a problem with the fuselage.It had a split at the bottom rear area.Looks like they didnt lay up the fiberglass properly.They sent me a new one ,so it goob to go.Post your build when you can.Thanks
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Old 01-09-2013, 06:52 AM
  #2057
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Default RE: KMP F-7F Tigercat

I recently started my F7F and decided to put CRRC gas engines from Maxford USA. It looks like the side carb version will be a good fit.
Carl
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Old 01-09-2013, 07:35 AM
  #2058
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Default RE: KMP F-7F Tigercat

Guys, I think the "parallel" build thread referred to is the RC Groups one (http://www.rcgroups.com/forums/showthread.php?t=1421377), although I might be wrong. That thread also had a renewed interest and life into it, which inspires me to complete my own build. My path is electric. Two Tacon 160 motors (245Kv) running two FreeWing 120HV ESCs (right now I'm debating where to put the ESCs, in the nacelles or the nose), 12S 5000mAh batteries (possibly 6800mAh or 8000mAh), AR9110 receiver with TWO receiver batteries connected to it (the last thing I need is a 30lb "bird" out of control in the air...). All the servos are already in place. I have the original air retract set, but yesterday ordered a V3 electric set as well. $319 for a tricycle electric set that can support (hopefully...) a 30lb plane including the struts and wheel is not a bad deal... I will clear my build area and bring this plane back there...
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Old 01-09-2013, 07:38 AM
  #2059
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Default RE: KMP F-7F Tigercat

Oh, and one more thing: I am going to use 18x12x2 props, but counter rotating. One prop will turn clockwise, and the other counter-clockwise. I bought Zinger props for this. The logic behind this is that none of the motors will be a "critical" motor, in case I lose one. Both props will turn TOWARD the fuse (when you look at where the TOP tips are going). I will put spring washers, and probably some holes and pins through the props and the shaft backplates. I'll post pictures when I do that.
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Old 01-09-2013, 10:06 PM
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Default RE: KMP F-7F Tigercat

YSO - Sounds good, but there is nothing like 2 Gasoline Engines ROARING through the air. Low passes at Full Bore and a lot of NOISE - I WET my PANTS. Keep us posted with your BUILD. Col. Chuck Winter
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Old 01-09-2013, 10:57 PM
  #2061
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Default RE: KMP F-7F Tigercat

Speed controllers should be as close to the motors as you can get them and the batteries in the nose 2x10s 5000mah is what I have and castle hv 85 and e flite power 160's 32 lbs. all up!
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Old 01-09-2013, 11:15 PM
  #2062
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Default RE: KMP F-7F Tigercat

Hello guys,

I work in my Tigercat for finish them. last work's electric retract by ESM and open/ close door:

It's is the résult:

[youtube]http://www.youtube.com/watch?v=-XZsPZmtrq0[/youtube]

Bye!
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Old 01-10-2013, 02:29 PM
  #2063
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Default RE: KMP F-7F Tigercat


Quote:
ORIGINAL: ysolomon

Oh, and one more thing: I am going to use 18x12x2 props, but counter rotating. One prop will turn clockwise, and the other counter-clockwise. I bought Zinger props for this. The logic behind this is that none of the motors will be a ''critical'' motor, in case I lose one. ...
Do the counter rotating props for the fun of it. After all, we're in this hobby for the love of aircraft and associated gadgets. However, in my one old opinion, banking on counter rotating props will buy you very little or nothing in an engine-out situation. The little opposite torque from the slow running live engine won't offset the huge amount of drag created by the dead engine side of the aircraft. As it has been said many times, you'd best be quick on the rudder and at reducing power to a manageable level and hope that you have enough altitude to make descending turns to the runway.
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Old 01-10-2013, 03:57 PM
  #2064
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Default RE: KMP F-7F Tigercat

I'm not sure that it will do NOTHING at all... But as you say, probably very little. Will look very cool on starting though... Let's hope I don't have a motor-out situation...
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Old 01-10-2013, 05:42 PM
  #2065
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Default RE: KMP F-7F Tigercat


Quote:
ORIGINAL: Ron McGrath

Speed controllers should be as close to the motors as you can get them and the batteries in the nose 2x10s 5000mah is what I have and castle hv 85 and e flite power 160's 32 lbs. all up!
This is not the way to set up a twin electric plane. I cant recall the terminolgy but when you have battery's far away from the motors you want the speed controls near the batteries and extend the motor wires. If you have the speed controls near the motor and the batteries far away then you will get feed back into the speed control and burn them up. Its post on the Castle website and many of the electric forums. you can get away with it but isnt good on the speed controls. I will look this up for you if you like. [X(]
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Old 01-10-2013, 06:00 PM
  #2066
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Default RE: KMP F-7F Tigercat

Wrong, wrong, wrong.

Castle was having issues with defective caps or poorly specified caps on their ESCs and/or people were using 60amp ESCs where they should have been using 80 amp ESCs. Needless to say there is a looong drawn out thread on RCG with no factual data. No scope traces, no ESC data logs. Just a whole lot of armchair inferencial data and people flogging caps and castle cap packs...

I fly many twins batteries 18 to 36 inches away from the ESCs (also my single engine models are like this) with NO issue whatsoever. I dont cheap out, I use the proper sized ESCs plus my EE training to laugh at the idiots who fall for the marketing gimmik.

I do have a pilot on RCCanada who had used an CC Ice 80 to log data for the standard ESC battery leads and a 12 in extension and guess what? Those mythical spikes were just that a myth!

ESCs at the motors is the way! But do whatever makes you quiver less. Really makes no diff except you add 3 wires full of electrical noise and have to worry about cooling the ESCs....

Quote:
ORIGINAL: airraptor


Quote:
ORIGINAL: Ron McGrath

Speed controllers should be as close to the motors as you can get them and the batteries in the nose 2x10s 5000mah is what I have and castle hv 85 and e flite power 160's 32 lbs. all up!
This is not the way to set up a twin electric plane. I cant recall the terminolgy but when you have battery's far away from the motors you want the speed controls near the batteries and extend the motor wires. If you have the speed controls near the motor and the batteries far away then you will get feed back into the speed control and burn them up. Its post on the Castle website and many of the electric forums. you can get away with it but isnt good on the speed controls. I will look this up for you if you like. [X(]
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Old 01-10-2013, 08:38 PM
  #2067
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Default RE: KMP F-7F Tigercat

Just for info... I fly a Taylorcraft 1/4 scale with CC ICE 100, SPS (emcotec), MUI (jeti)... cables are 80cm (*2)... I added a 2200µF cap on the SPS (designed for), there is no problem.
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Old 01-10-2013, 10:21 PM
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Default RE: KMP F-7F Tigercat

lol Well When i read those threads the majority seemd to favor the three wire extension over the two. I would never build this plane as electric anyway. Mine will be DLE 35's or Rotomoto 35 Four strokes. I have the V-2 E retracts from ESM and they said they will upgrade them but still not confident in them to start the building of this plane
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Old 01-11-2013, 06:30 AM
  #2069
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Default RE: KMP F-7F Tigercat

Yes, there are two schools of thoughts as far as extending the ESC wires. One thing for sureunless I put the batteries in the nacelles (which I will not...)I need to extend wires. Now MY EE background comes into play... The problem with extending the motor wires is that those signals are switching at some 12-32KHz, switching very high current. Further more, whenever two of them are "on" (one on + and one on -), the third one is providing signal back to the ESC for timing purposes. Furthermorethere is some delay on those wires, although not enough to cause a problem. The other problem with extending those wires is that the ESCs need to find some good spot in the fuselage that will be cooled enough. Having said thatI'm going to run HobbyWing 120A HV ESCs, capable of handling 6,000W (give or take) each, and "ask" them to deliver 2,000-2,500W each, which should keep them relatively cool. So, not a big problem.

On the other hand, extending the battery wires can cause spikes during switching of the motor, as those wires act as inductors, that will not allow current changes in zero time, and thus cause very high voltage spikes to develop, which might burn the power FETs in the ESC. However, using thick wires (I'm going to be using 10AWG), and given that the current, again, will be relatively low at about 40-45A, may eliminate this problem. Add to that capacitors along the way between the batteries and the ESCand this would not be a problem at all. I think this is what I will end up doing, but I'm not there yet...
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Old 01-11-2013, 06:38 AM
  #2070
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Default RE: KMP F-7F Tigercat


Quote:
ORIGINAL: airraptor

lol Well When i read those threads the majority seemd to favor the three wire extension over the two. I would never build this plane as electric anyway. Mine will be DLE 35's or Rotomoto 35 Four strokes. I have the V-2 E retracts from ESM and they said they will upgrade them but still not confident in them to start the building of this plane
I would be vary carefule of engine choice. DLE 35's will be way over powered. If you have a engine out, It will become a frisbee in a second. 20cc to 26cc is more than adequate. DLE 20's will fly it scale and then some.
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Old 01-11-2013, 06:41 AM
  #2071
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Default RE: KMP F-7F Tigercat

For info... my mosquito has two Scorpion 5525/225 with CC ICE2 HV 80 and two 12s2p a123 in the nacelle.
Better to have two packs instead of one...
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Old 01-11-2013, 08:36 AM
  #2072
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Default RE: KMP F-7F Tigercat

Ordered my retracts and brakes from Darrell at Sierra today! I am also thinking about how to use my Spektrum DX8 with a twin. This radio is new for me, it replaces my JR XP8103. Email conversation with Andy Kunz suggesting JR MatchBox could help in getting the engines in sync throughout throttle range. From this thread I understand I want to get the engines synchronized as closely as possible mechanically first, but the matchbox sounds like a simple way to make fine tuning adjustments. Any thoughts?

Don
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Old 01-11-2013, 09:10 AM
  #2073
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Default RE: KMP F-7F Tigercat

Depending on the ESC you use...
On CC don't let them define their range auto...
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Old 01-11-2013, 09:11 AM
  #2074
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Default RE: KMP F-7F Tigercat

Yes but that is what the left stick is for..... Doesnt matter to me if a low power or extreme power if and engine quits i will manage the plane to make a safe landing. High power at low speeds yes that might happen but I will not horse this thing off the ground at low speed

Rotomoto 35's are my first choice then the DLE 35 as I will use the Beila 3 blade scale 18x10 prop at around 5,500-6,000 rpm.
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Old 01-11-2013, 09:13 AM
  #2075
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Default RE: KMP F-7F Tigercat


Quote:
ORIGINAL: donddsms

Ordered my retracts and brakes from Darrell at Sierra today! I am also thinking about how to use my Spektrum DX8 with a twin. This radio is new for me, it replaces my JR XP8103. Email conversation with Andy Kunz suggesting JR MatchBox could help in getting the engines in sync throughout throttle range. From this thread I understand I want to get the engines synchronized as closely as possible mechanically first, but the matchbox sounds like a simple way to make fine tuning adjustments. Any thoughts?

Don
Congrats on getting the best retracts for this model. You will be glad you got them later. As far as using a matchbox for throttle's, That will work but it may be easier to mix a channel such as throttle and channel 7 or 8 because you can make small adjustments while it running. A matchbox you would have to stop it every time. Just my 2 pennies
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