KMP F-7F Tigercat
01-30-2013, 06:31 AM
#2101
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RE: KMP F-7F Tigercat
Somehow I do not think your numbers add up I have a 10 ah pack and fly a little over half stick on the throttle for all the straight and level flight verticals and the first part of my takeoff roll are full throttle I get a safe 5.5 min flight (20 to 25% left in pack) I do not know what the capacity of your packs are but they are of a heavier design and possibly lower c rating I would doubt that it is possible to double my flight time or even make it to 8 min.
01-30-2013, 07:28 AM
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RE: KMP F-7F Tigercat
Thanks but your details are not pertinent to this discussion. I could fly the taylorcraft on a rubber band & a stong breeze for 5 mins the wing is so big..
Your setup is for something like a cub & we are talking about a heavy wing loadind warbird.
Your setup is for something like a cub & we are talking about a heavy wing loadind warbird.
01-30-2013, 08:22 AM
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RE: KMP F-7F Tigercat
@ron... on my Taylorcraft I installed 7s2p a123, that's 4.6Ah, the Hacker A60-6xs turns a 20*13 prop at 40% thr in horizontal flights. I get figures the following way : timer is active when thr > 15%, I get mAh from my iCharger when reloading at the field and I extrapolate. 8 to 12 min is the interpolation with no reserve. I set flight timer to 6 min. Data are crosschecked with logging on the CC ICE 100.
@dangaras... you are right... my Taylorcraft weights 7kg and has a lot of spare power (but short wings). People say : 250W/kg for a sport plane... I am building a 100" mosquito, planned weight 12kg, planned power min 3000W... a pair of Hacker like the one of the Taylorcraft gives 3800W... it seem OK to me. What's your ratio ?
@dangaras... you are right... my Taylorcraft weights 7kg and has a lot of spare power (but short wings). People say : 250W/kg for a sport plane... I am building a 100" mosquito, planned weight 12kg, planned power min 3000W... a pair of Hacker like the one of the Taylorcraft gives 3800W... it seem OK to me. What's your ratio ?
01-30-2013, 09:11 AM
#2105
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RE: KMP F-7F Tigercat
I also have a Stinson 108 27lbs 10 ah battery the same as in the Tigercat and only one motor. I can fly the Stinson for 25 min. it is just not the same. With the tigercat I am going to guess that you will be at a minimum of 48% less flight time because a 7s a123 setup has 60% of the voltage a 10s Lipo setup has then you are only 92% of the battery over all capacity so even if the packs are the same c rating maximum discharge currents are lower and results in higher voltage drop and less watts.
01-30-2013, 09:38 AM
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RE: KMP F-7F Tigercat
@ron... you are right, but you have got my real life figures...
Another graph shows voltage drop under maximum power... it's relatively high but you have to know that between the battery and the controller, I have also a SPS main switch and a Jeti MUI for telemetry.
a123 cells are design for 70A each (120A peak). Current is not critical.
Another graph shows voltage drop under maximum power... it's relatively high but you have to know that between the battery and the controller, I have also a SPS main switch and a Jeti MUI for telemetry.
a123 cells are design for 70A each (120A peak). Current is not critical.
01-30-2013, 09:53 AM
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RE: KMP F-7F Tigercat
I will be generating almost 4000W for the Tigercat.. Now it is supposed to be 30lbs AUW. My 92" A-26 weighs about 16.5lbs and max power is about 2300W on 5 cells. I went from Turnigy SK42-50-650Kv to Aolean 42-60-600Kv and saw an amazing change in power and performance.
01-30-2013, 09:42 PM
#2108
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RE: KMP F-7F Tigercat
My first choice for my Mossie was a pair of Scorpion 5525/225 turning 18*12*3 props with CC ICE2 80 and two 12s2p a123.
That's 3.5kg for both packs, too high... In Belgium, we have a lot of administrative paper to fill for any plane heavier than 12kg all included.
The alternative was to change for LiPos (I don't like LiPos) or to find a motor with enough power and less a123 cells.
That's the reason for the Hacker. It turns under 7s2p a123 i.e. 1kg per pack, 2kg total instead of 3.5kg...
I am open to any alternative because the Hacker is very expensive...
That's 3.5kg for both packs, too high... In Belgium, we have a lot of administrative paper to fill for any plane heavier than 12kg all included.
The alternative was to change for LiPos (I don't like LiPos) or to find a motor with enough power and less a123 cells.
That's the reason for the Hacker. It turns under 7s2p a123 i.e. 1kg per pack, 2kg total instead of 3.5kg...
I am open to any alternative because the Hacker is very expensive...
02-13-2013, 07:35 AM
#2117
RE: KMP F-7F Tigercat
Wow the DB cockpit at $99 seems a little steep for a single cockpit only, but it does look great and for sure value is in the eye of the beholder. As a turbine jet guy myself I've spent hundreds at a time on cockpits, and I am guilty as charged... but the most gratifying ones for me were cheap custom ones I built myself. I have made many cockpits from plastic styrene sheet and Testors paints, usually the whole thing costs about $10 to build using plastic, model cement, and a color printer using photoshop to print out instruments panels. An alternative is to buy the Top Flite 1/7 Corsair cockpit kit and stretch the kit into two cockpits with spare styrene sheets for less than $30, or just buy two (for $52 for both) and use parts from the second and a few bits if plastic to make the second "pit" more purpose looking if one is trying to save weight and money. I've used the Top Flite kits in high dollar jets that were not completely scale but gave the illusion of scale for a good weight and price. Plus many specific cockpits sold out there are not really scale to begin with, they are sorta scale and the sins of using another cockpit that is very close is no farther away from scale at times. Just a few ideas. (pictures below are not mine, but they are of the cheap TF Corsair cockpit that could be customized for an F-7F)
Oh, edit - to save some money and time, you can buy a pre painted ARF cockpit for the Gold Edition Corsair .61 ARF for less than $18 if customization of the "kit" is not important. You'd need a few bits of balsa to frame it under the plastic parts in but it would be simple and easy.
http://www3.towerhobbies.com/cgi-bin...?&I=LXBAND&P=7
or
http://www3.towerhobbies.com/cgi-bin...?&I=LXHZ04&P=7
not sure what the difference is between the cockpit kits but same price
Oh, edit - to save some money and time, you can buy a pre painted ARF cockpit for the Gold Edition Corsair .61 ARF for less than $18 if customization of the "kit" is not important. You'd need a few bits of balsa to frame it under the plastic parts in but it would be simple and easy.
http://www3.towerhobbies.com/cgi-bin...?&I=LXBAND&P=7
or
http://www3.towerhobbies.com/cgi-bin...?&I=LXHZ04&P=7
not sure what the difference is between the cockpit kits but same price
02-13-2013, 09:53 AM
#2118
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RE: KMP F-7F Tigercat
You get both cockpits, not just one. Front and Rear... I bought one and put it together. The DB also comes with a step by step assembly DVD so you don't hack up your deck in experimentation. There isn't much room on that ESM F7F to experiment.
05-06-2013, 11:51 AM
#2119
RE: KMP F-7F Tigercat
Just keeping this thread alive! I got my hands on an original, barely started composite KMP kit. Power is the new OS 22 GT gassers. It was a bit of work to get them to fit but they are completely concealed within the cowls. I plan on starting with the 3 blade master airscrew 14x9s as they have proven to be highly effective in powering my first, and still flying, Tigercat. Here are a few pix.
05-26-2013, 10:31 PM
#2122
RE: KMP F-7F Tigercat
Hi Tigercat Guys. Had a Great weekend at Castle Airport located at Atwater Cal. It was the IMAA Mini-Fest. Great flying location with thousands of feet of concrete in all directions. My Tigercat was one of the HITS at the show. People are surprised at the speed and smooth running of my Fuji engines. Chuck Winter PS. Having problems sending pictures AGAIN...
05-31-2013, 07:33 AM
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RE: KMP F-7F Tigercat
Hi Chuck, Microsoft Office is a good program on one's computer to downsize the size of the pixels in your photos. Thereby making them downloadable. I do this all the time. I have a digital camera that takes pics that are in megabytes. After I downsize the picture and save it as such, it makes them about 3-400 kilobytes which the program in RC Universe can handle. I know it's frustrating to get some great footage, and can't share it.....
05-31-2013, 07:41 AM
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RE: KMP F-7F Tigercat
My bird is laid up for a while. I have decided to switch from 72 Mghrz to 2.4 with it. What I am afraid of is the 13 fast high torque digital servos going through the receiver. Owning a KMP full composite, I certainly do not want to lose it with a stupid brown out. I am saving the money to install a power distribution board that funnels all that amperage through the board and not the receiver. It seems to be a logical solution. Especially when a friend of mine used high end HD servos in his Yak and it browned out!!! Luckily it was on the bench. Those HD's seem to draw a lot of amperage.