Official FlightLine RC 1600mm F7F-3 Tigercat Thread

[rekit500]

Thanks all. I measure from the front of the wing at the root, next to fuselage, on the bottom of the wing. I must have a "special" 'cat cuz all my wheels go to the rear when they dissappear! That's why I wasn't surprised at the pitch up.

[themudduck]

Rekit500, its true that the balance point will move back slightly when the gear comes up (as you said, the gear retracts rearwards) but its not a big deal. It can be a good thing. Setting the recommended balance point with the wheels down make the model slightly nose-heavy. That is a desirable thing during landing and takeoff, since the plane is somewhat more stable that way. It also helps when the flaps are down. With the gear up and the balance point shifted back a little, the plane is more maneuverable - which is exactly what you want for a fighter.

The last thing Marine aviators needed when coming in for a landing was to deal with a tail-heavy airplane. We don't need that either!

I'm just guessing, because you didn't mention whether you used flaps, but the flaps do cause the model to pitch up rather strongly. You'll need to trim the elevator down when deploying the flaps. My maiden flight (with takeoff flaps set, and elevator trimmed with too much "up") resulted in a wild takeoff that almost went vertical. When adjusted correctly for the flaps, it takes off normally and I haven't noticed any pitch-up when the gear retracts during any of my subsequent flights. Of course, I should note that when the gear is coming up, I am climbing out.....

[OV10]

I must have a "special" 'cat cuz all my wheels go to the rear when they dissappear!

LOL What was Alpha thinking that these gears retract forward LOL

[Plastic_Aviator]

Hey guys,

Quick question about the new Admiral 3600's. These new ones are square so from what I've read in previous posts, they wont fit. Has anyone figured out a way to fit them in the plane without too much surgery? If so, would you mind posting your workaround and maybe a pic or two?

Thanks

[rekit500]

I've got it set pretty close now, just needed 5% up elevator when gear is down. That way I am running neutral elev with gear up. Does anyone know why or how the gear has the delay and how to get rid of it? I also don't see any need for flaps as it takes off in 30" feet w/o them and floats in. In the interest of longer flight times I'm going to unplug the 4 flap servos and the landing light, just to see. I know it won't be much different...but dang, I just get grooving and the timer starts harassing me. Next is to mix the rudder to ail and speed up the roll rate. I think this will mess up inverted flight a little, I may have to put that on a switch.

[xviper]

I've got it set pretty close now, just needed 5% up elevator when gear is down. That way I am running neutral elev with gear up. Does anyone know why or how the gear has the delay and how to get rid of it? I also don't see any need for flaps as it takes off in 30" feet w/o them and floats in. In the interest of longer flight times I'm going to unplug the 4 flap servos and the landing light, just to see. I know it won't be much different...but dang, I just get grooving and the timer starts harassing me. Next is to mix the rudder to ail and speed up the roll rate. I think this will mess up inverted flight a little, I may have to put that on a switch.

Wow, does the gear being down change the balance that critically? Or is it due to drag pulling the plane down?
I think the speed that most retracts deploy is built into the retract itself. I doubt you can do anything to change it. You can confirm this by hooking one up to a servo tester and deploying it that way. If it's still slow, then it's built in. If it speeds up, then it could be due to the retracts going through a control board. If that's the case, you can wire them up directly to your receiver. Modelers, in general through the years, have strived to make retracts slow down to be more realistic. You want to speed them up?

[Beeg]

I've got it set pretty close now, just needed 5% up elevator when gear is down. That way I am running neutral elev with gear up. Does anyone know why or how the gear has the delay and how to get rid of it? I also don't see any need for flaps as it takes off in 30" feet w/o them and floats in. In the interest of longer flight times I'm going to unplug the 4 flap servos and the landing light, just to see. I know it won't be much different...but dang, I just get grooving and the timer starts harassing me. Next is to mix the rudder to ail and speed up the roll rate. I think this will mess up inverted flight a little, I may have to put that on a switch.

xviper2,
it's not the speed of the gear it's the delay from when you flip the switch to when they actually start to retract.

rekit500,
The gear are tied into the controller board that was programmed to include separate gear door servos, which they elected not to install to save weight and complexity. Hence the gear delay. If you want to eliminate the delay you just bypass the controller board with "Y" connectors directly into your receiver gear port.

Not sure what's up with your specific model but you are still the first person that's indicated a noticeable pitching moment with gear retraction. Oh well, sounds like you got that one solved.

[xviper]

xviper2, it's not the speed of the gear it's the delay from when you flip the switch to when they actually start to retract.

The gear are tied into the controller board that was programmed to include separate gear door servos, which they elected not to install to save weight and complexity. Hence the gear delay. If you want to eliminate the delay you just bypass the controller board with "Y" connectors directly into your receiver gear port.

Not sure what's up with your specific model but you are still the first person that's indicated a noticeable pitching moment with gear retraction. Oh well, sounds like you got that one solved.

I see. That explains it pretty well. Yes, by-pass the control board and hook the gear up directly to the RX.

[rekit500]

B/P board sounds reasonable. Would have to bypass ribbon as well for the gear. Probably just deal with it. As far as pitch up-balance your cat on a decent stand and retract the gear and see if it doesn't pitch up. It would take a new set of physics if it doesn't. I'm still surprised no one else has this (small) issue. I think I have a decent airframe, it flew hands off with just a few cliks of this or that. But it did need I think around 5 cliks to level it when I pulled the gear up before I did the mix. Elevator feels right, not too powerful.

[rekit500]

I would like to add that I bought the Hi Power set up along with the original purchase of the F7F. I never intended to use the stock motors, was kinda pissed I couldn't order it this way. Then I got them and one had a bent something. MRC was great, Sent a new motor quickly (thanks) It was better, not perfect, but useable. Bottom line--no perceptible performance improvement and battery life took a hit.

[themudduck]

As far as pitch up-balance your cat on a decent stand and retract the gear and see if it doesn't pitch up. It would take a new set of physics if it doesn't. I'm still surprised no one else has this (small) issue. I think I have a decent airframe, it flew hands off with just a few cliks of this or that. But it did need I think around 5 cliks to level it when I pulled the gear up before I did the mix. Elevator feels right, not too powerful.

I'm sure that retracting the gear will move the balance back a bit, which will have some effect on the flying characteristics - I just haven't noticed it. Most likely because I've trimmed my plane for level flight with the gear up. In other words, when I put the gear down I guess it pitches down a bit and that's fine, a little extra stability is welcome during landing.

However if you guys are experiencing some pitch-up when you retract the gear, why not program your radio to add a little bit of down-elevator trim to compensate for that. That way you won't have to manually set a different trim setting when the gear is retracted.

[OV10]

I'm sure that retracting the gear will move the balance back a bit, which will have some effect on the flying characteristics - I just haven't noticed it. Most likely because I've trimmed my plane for level flight with the gear was up. In other words, when I put the gear down I guess it pitches down a bit and that's fine, a little extra stability is welcome during landing.

However if you guys are experiencing some pitch-up when you retract the gear, why not program your radio to add a little bit of down-elevator trim to compensate for that. That way you won't have to manually set a different trim setting when the gear is retracted.

The most likely reason that Rekit500 hasn't heard ALOT of concerns from others about pitching up during gear up operations is because of the exact reason TMD explained that I highlighted in blue.
As the engineers do with full scale with aft retracting gear......the CG is set with the gear retracted. This is because the majority of the flight envelope is in this position.
It is a better approach to be slightly nose heavy for landing than to be slightly tail heavy during the majority of the flight
All my aft retracting birds (F6F, P-40, F4U, P-38 and this F7F) have the CG set in the retracted position with a neutral elevator.
This requires only a slight amount of up elevator trim programmed in during gear down.
The other advantage that is totally missed by those that do not CG via this "normal" convention is that with the down elevator trim(as highlighted in red) it does not provide a relatively neutral position for inverted flight.
This in turn requires a lot of down pressure to hold level flight while inverted which can be/is intimidating especially a lower altitudes.
A good indication of whether the CG is in a null position is when the elevator is neutral for both upright and inverted flight. (Ask any pattern contest pilot)
Hope that my explanation has helped those inquiring minds to understand. ;)
Best regards,

[themudduck]

The most likely reason that Rekit500 hasn't heard ALOT of concerns from others about pitching up during gear up operations is because of the exact reason TMD explained that I highlighted in blue.
As the engineers do with full scale with aft retracting gear......the CG is set with the gear retracted. This is because the majority of the flight envelope is in this position.
It is a better approach to be slightly nose heavy for landing than to be slightly tail heavy during the majority of the flight
All my aft retracting birds (F6F, P-40, F4U, P-38 and this F7F) have the CG set in the retracted position with a neutral elevator.
This requires only a slight amount of up elevator trim programmed in during gear down.
The other advantage that is totally missed by those that do not CG via this "normal" convention is that with the down elevator trim(as highlighted in red) it does not provide a relatively neutral position for inverted flight.
This in turn requires a lot of down pressure to hold level flight while inverted which can be/is intimidating especially a lower altitudes.
A good indication of whether the CG is in a null position is when the elevator is neutral for both upright and inverted flight. (Ask any pattern contest pilot)
Hope that my explanation has helped those inquiring minds to understand. ;)
Best regards,

Thanks, them's helpful comments there.
Let me add, regarding my idea (the part you highlighted in red) to use a mix when the gear is raised... well, instead of programming a mix to add some down trim when the gear is retracted, you could use the mix the other way - I mean, mix in a little "up" trim when the gear is placed in the down position. That way it wouldn't affect inverted flight like you pointed out. And since the added trim would be automatically removed when the gear was retracted, it would help with the pitch-up as well.

[OV10]

Thanks, them's helpful comments there.
Let me add, regarding my idea (the part you highlighted in red) to use a mix when the gear is raised... well, instead of programming a mix to add some down trim when the gear is retracted, you could use the mix the other way - I mean, mix in a little "up" trim when the gear is placed in the down position. That way it wouldn't affect inverted flight like you pointed out. And since the added trim would be automatically removed when the gear was retracted, it would help with the pitch-up as well.

I indicated that in the middle of my blurbLOL.......good to point it out again.;)

[ronwc]

This really is a fantastic plane, very well designed and flies great, very good deal for the money. I bought it about 3 weeks ago and have been flying it almost everyday for the last two weeks. Plane is very solid feeling in the air, really no bad tendencies. I was somewhat surprised at how efficient it is with lipos, I was used to the power hungry 90mm jets which get about 3 minutes on a 5000 lipo. I am using two 2700 which get about 5 minutes and two 3700 which get about 8 minutes, lipos barely get warm. I think the airspeed and climb are just right for this type of plane, and I am usually a speed junkie.

One trick I used on it was to mix a little rudder into ailerons to get a faster roll rate. I also have 7% down elevator with flaps. I saw some guys were talking about trim changes with gear up or down, I trim my planes with gear up and don't really feel much of a difference. Landings are very easy with or without flaps, although flaps definitely help when there is no headwind.

One maneuver I was practicing this morning was to come downwind full throttle about 3 feet altitude down the runway, pull up about 45 degrees at the end of runway and do a slow roll while climbing into a split S. When plane gets inverted and starting to come down hill, cut throttle, drop gear/flaps and land or do touch and go.

[themudduck]

This really is a fantastic plane, very well designed and flies great, very good deal for the money. I bought it about 3 weeks ago and have been flying it almost everyday for the last two weeks. Plane is very solid feeling in the air, really no bad tendencies. I was somewhat surprised at how efficient it is with lipos, I was used to the power hungry 90mm jets which get about 3 minutes on a 5000 lipo. I am using two 2700 which get about 5 minutes and two 3700 which get about 8 minutes, lipos barely get warm. I think the airspeed and climb are just right for this type of plane, and I am usually a speed junkie.

One trick I used on it was to mix a little rudder into ailerons to get a faster roll rate. I also have 7% down elevator with flaps. I saw some guys were talking about trim changes with gear up or down, I trim my planes with gear up and don't really feel much of a difference. Landings are very easy with or without flaps, although flaps definitely help when there is no headwind.

One maneuver I was practicing this morning was to come downwind full throttle about 3 feet altitude down the runway, pull up about 45 degrees at the end of runway and do a slow roll while climbing into a split S. When plane gets inverted and starting to come down hill, cut throttle, drop gear/flaps and land or do touch and go.

Good job Ron! I really love this plane as well. I agree with what you wrote about the rudder - I found that it was a bit sluggish doing rolls, and then I mixed in a little rudder and it is much more responsive,
Of course it's on a switch, so I can turn off the mix if I want. but I usually just leave it on all the time. Two nice flights yesterday, it couldn't be better!

[themudduck]

Well, yesterday I was at a nice fun-fly meet at a local club (the Alliance OH Balsa Bees) and I took out my Tigercat and A-10. Multiple flights with both planes, it was terrific. An interested spectator came up and wanted to know more about my Tigercat. Turns out, Mr. Robert Mueller is a Korean War veteran and served with a Tigercat F7F-3N night-fighter squadron. You can see his hat and T-shirt. He was excited to see my model and I was excited to get his picture with it! Lots of fun.

[TiredIronGRB]

That's awesome!

[Grossman56]

that's just too cool themudduck.
Never miss the opportunity to get a vet in the pic, especially one who flew your plane.

Grossman56

[MesRcPilot]

Hi Themudduck,very impressive photo... this will be your valuable memory :p38