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Mar 16, 2009, 09:03 AM
Fear is the mind killer
BustedBlades's Avatar
Quote:
Originally Posted by ashtasky
Hello yarsmythejr,
After reading thru these posts i strarted making one. I increased the Fuse length by about 2 inches, in order to balance the F&L at 2.5 inches from the leading edge.
After assembly, balanced the plane correctly and did the maiden today.
It flew straight. But within seconds, when i was turning the plane it banked on to the left (it is not actually banking, it turns as if thru rudder) and crashed.
Repaired the plane in the field itself and tried again, this time changed the prop to an APC 90X43,( Initially it was 80X4.3 prop. I am using waypoint 2212-22) This time it flew better but always had a tendency to bank? (yaw) and crash in the turns. It is not due to the aelerons high rates. Definitely betwenn 80X43 and a 90X4.7 props there is a difference and with 90X4.7 i am able to fly but still not comfortably.
Can you people help me to identify the problem: some of my thinking is.
1. Is there a problem since the fuse length is increased by almost 2 inches?
2. I have mounted the motor staright w/o any right or down thrust. is this a problem.
3. When u increase the fuse length by 2 inches will the CG change. ( I have balanced it at 2.5".
my auw is 15.8 oz

Here are some build photos.

Ashta
My center is directly under the wooden wing spar and mine flies perfectly balanced. If it is in level flight and I cut the throttle to nothing, it will nose down 5 degrees and float till it lands. Try shifting the battery and other electrics to get the center under the wing spar, and of course, make sure you are balanced left to right.
Also, I notice the left aileron is not flush with the tail edge of the wing and the right one is. Makes me think they are not the same size.
One more thing, make sure you setup your ailerons to throw the correct direction with stick input.
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Mar 16, 2009, 09:07 AM
Lee / RC Enthusiast
YarSmythe's Avatar
Thread OP
Quote:
Originally Posted by ashtasky
Can you people help me to identify the problem: some of my thinking is. 1. Is there a problem since the fuse length is increased by almost 2 inches? 2. I have mounted the motor staright w/o any right or down thrust. is this a problem. 3. When u increase the fuse length by 2 inches will the CG change.
Ashta,

The first two things that popped into my head was your motor position and the CG. From the photo, your motor appears to be located much further forward than the standard plans. This may cause some problems with the elevator. Second, the CG position is critical to the wing. It shouldn't be past the midway point of your wing. The typical rule of your CG position is 1/3rd to 1/2th the distance from your leading edge. Most of the time is very close to the spar. If your plane 'snap rolled', then it typically suggests your CG is too far back (tail heavy).

That said, my "Orange Bang" actually flies a little better tail heavy (CG back). So sometimes rules can be fudged.

Another thing to consider is your horizontal balance. My mini-F&L is right wing heavy. I had to add weight to the left wing. Have you looked at yours?

As for the motor angle...all of mine are straight. No down/right thrust.

Don't give up. We'll figure this one out for you.

-Lee
Mar 16, 2009, 09:27 AM
A real WingNut
j4ck4's Avatar
Quote:
Originally Posted by ashtasky
Hello yarsmythejr,
After reading thru these posts i strarted making one. I increased the Fuse length by about 2 inches, in order to balance the F&L at 2.5 inches from the leading edge.
After assembly, balanced the plane correctly and did the maiden today.
It flew straight. But within seconds, when i was turning the plane it banked on to the left (it is not actually banking, it turns as if thru rudder) and crashed.
Repaired the plane in the field itself and tried again, this time changed the prop to an APC 90X43,( Initially it was 80X4.3 prop. I am using waypoint 2212-22) This time it flew better but always had a tendency to bank? (yaw) and crash in the turns. It is not due to the aelerons high rates. Definitely betwenn 80X43 and a 90X4.7 props there is a difference and with 90X4.7 i am able to fly but still not comfortably.
Can you people help me to identify the problem: some of my thinking is.
1. Is there a problem since the fuse length is increased by almost 2 inches?
2. I have mounted the motor staright w/o any right or down thrust. is this a problem.
3. When u increase the fuse length by 2 inches will the CG change. ( I have balanced it at 2.5".
my auw is 15.8 oz

Here are some build photos.

Ashta
It is possible that your balance is off left to right. Have you checked to make sure you are balanced this direction.
Mar 16, 2009, 04:45 PM
Hole digger
DampRabbit's Avatar
Quote:
Originally Posted by DanT
IMO your plane has a swept leading edge, that will change the balance point or CG , will not fly the same. Next the spares on top ? When you have a good spot for them on the bottom of the main wing next to the KF? Have Fun.
I put the spars on top since that's closer to how the real plane does it. On the real one they sweep up but that seemed too difficult so I just put them on top. This is just a sketch to play with the idea.

My biggest problem with this plane is I already have too many, I have to crash something to make room.
Mar 17, 2009, 01:28 AM
Registered User

Thanks


THANKS FOR UR TIME.
My xmter is Futaba 7C. My rcvr is GWS R6. My servos are 9gms. My motor is WAYPOINT 2212. My esc is Thunder bird 18A.
By making the nose longer, i wanted to be able to put the battery more in to the centre of the fuse rather than close to the nose. (save battery on crash)Keeping the CG at 2.5 inches from the leading edge as given in the plan.
Aelerons are in the right direction.
I weighed both Aluminium and wooden spar before deciding on aluminium tube.
lateral balance: I WILL CHECK IT MORE CAREFULLY.





Quote:
Originally Posted by DanT
I am not the designer , but I have been in RC for over 20 years. Also, it hard to help when you don't tell us what you are using for Radio setup?
1. making the nose longer , ( on this design ) will not change the cg IMO.(( or balance point )) I fly mine at about 2 3/4" for leading edge.
2. My motor has no down and almost no right in it.
Looking at your plane , changing your props will not make anything bank, my guess is bad servo? Wrong cg? Did you setup ailerons to move in the right way? Bad receiver ? ( GWS receivers are JUNK IMO )
CG or balance point, I see a lot of people who don't use a bubble level , and just eyeball it. And standing off to one side watching them do it, I can see they are way off. Make sure you REAL ARE level at the cg! Ailerons , (yaw ), to much down travel then up can cause ( yaw).
PS: aluminum arrows are very heavy . And bend very easily .
Mar 17, 2009, 01:38 AM
Registered User

Thanks


Quote:
Originally Posted by BustedBlades
My center is directly under the wooden wing spar and mine flies perfectly balanced. If it is in level flight and I cut the throttle to nothing, it will nose down 5 degrees and float till it lands. Try shifting the battery and other electrics to get the center under the wing spar, and of course, make sure you are balanced left to right.
Also, I notice the left aileron is not flush with the tail edge of the wing and the right one is. Makes me think they are not the same size.
One more thing, make sure you setup your ailerons to throw the correct direction with stick input.

thanks for ur time and comments. i will try shifting the CG. Also i will cjheck for lateral balance more accurately
The photo is w/o power on and arming the servos. Hence the mis alignment of aelerons. and is perfect after arming the servos.
Mar 17, 2009, 01:43 AM
Registered User
Quote:
Originally Posted by yarsmythejr
Ashta,

The first two things that popped into my head was your motor position and the CG. From the photo, your motor appears to be located much further forward than the standard plans. This may cause some problems with the elevator. Second, the CG position is critical to the wing. It shouldn't be past the midway point of your wing. The typical rule of your CG position is 1/3rd to 1/2th the distance from your leading edge. Most of the time is very close to the spar. If your plane 'snap rolled', then it typically suggests your CG is too far back (tail heavy).

That said, my "Orange Bang" actually flies a little better tail heavy (CG back). So sometimes rules can be fudged.

Another thing to consider is your horizontal balance. My mini-F&L is right wing heavy. I had to add weight to the left wing. Have you looked at yours?

As for the motor angle...all of mine are straight. No down/right thrust.

Don't give up. We'll figure this one out for you.

-Lee
the CG as per plan was 2.5 inch from the leading edge. so i balanced it exatly.
I will play aroung with the CG and try.
also i will check for laterla balance more carefully. thanks for encouragement
ashta
Mar 17, 2009, 09:26 AM
Unrepentant Carnivore
jamesdr's Avatar

Defunderland Vampire


I've been REALLY thinking of this one. Did some research on the deHaviland Vampire and just may be cuttin' foam soon. Maybe do it as a pusher? Man - I love FFF!

Jim
Mar 17, 2009, 12:07 PM
3DHS 'native'
going4speed's Avatar
I added two inches to the front of mine and it flew awesome till I got blown into a tree....I swear it was the wind!!

Anyway, I have the same problem with a street fighter foamy also on this forum.

It flew great for the first flights and then I moved the motor back a 1/2 inch and then it wanted to roll to the right all the time. I have therefore decided to rebuild the nose in hopes I had some weird motor thrust angle issue. Hopefully get to test my theory tonight if the winds stay down like they did yesterday.

Quote:
Originally Posted by ashtasky
Hello yarsmythejr,
After reading thru these posts i strarted making one. I increased the Fuse length by about 2 inches, in order to balance the F&L at 2.5 inches from the leading edge.
After assembly, balanced the plane correctly and did the maiden today.
It flew straight. But within seconds, when i was turning the plane it banked on to the left (it is not actually banking, it turns as if thru rudder) and crashed.
Repaired the plane in the field itself and tried again, this time changed the prop to an APC 90X43,( Initially it was 80X4.3 prop. I am using waypoint 2212-22) This time it flew better but always had a tendency to bank? (yaw) and crash in the turns. It is not due to the aelerons high rates. Definitely betwenn 80X43 and a 90X4.7 props there is a difference and with 90X4.7 i am able to fly but still not comfortably.
Can you people help me to identify the problem: some of my thinking is.
1. Is there a problem since the fuse length is increased by almost 2 inches?
2. I have mounted the motor staright w/o any right or down thrust. is this a problem.
3. When u increase the fuse length by 2 inches will the CG change. ( I have balanced it at 2.5".
my auw is 15.8 oz

Here are some build photos.

Ashta
Mar 17, 2009, 11:34 PM
Hole digger
DampRabbit's Avatar
Quote:
Originally Posted by jamesdr
I've been REALLY thinking of this one. Did some research on the deHaviland Vampire and just may be cuttin' foam soon. Maybe do it as a pusher? Man - I love FFF!

Jim
Let me know if you want some drawings or a mock up in a certain size, I love tinkering on the computer

Notice the real Vampires have two kinds of tails. One close to what I modeled, kinda egg shaped with a bump, and a more concave curved one with the horizontal stab coming a bit past the verticals
Mar 18, 2009, 04:46 PM
Fear is the mind killer
BustedBlades's Avatar
Is anyone else's F&L too quiet? My F&L seems to be very quiet for how powerful it is. I can't really hear how much power I am putting into it, although I can see it accelerate like greased lightning. Even at full throttle it just hums a little. In a high speed dive at 1/2 throttle the wind noise is louder than the motor. I used an E-Flight stick mount on a 3/8"x3/8" stock hot glued into my fuselage. I am using a 10x6 APC speed prop. Maybe they are really efficient. I guess I need to try a wooden prop or something.

Hebert
Mar 18, 2009, 05:33 PM
Hole digger
DampRabbit's Avatar
Quote:
Originally Posted by BustedBlades
Is anyone else's F&L too quiet?
No such thing

Mine acts like a soundboard and all the squeaks and creeks come off the wing like it's an acoustic guitar. But the motor is pretty quiet. A smaller prop turning faster might give you more audio feedback.
Mar 18, 2009, 05:50 PM
Hole digger
DampRabbit's Avatar
Quote:
Originally Posted by jamesdr
Did some research on the deHaviland Vampire and just may be cuttin' foam soon. Maybe do it as a pusher? Man - I love FFF!
A pusher would be cool though the Vampire has it's spars much closer together than the P38. On my 26" wingspan mockup I show 6.19 inches between the spars.

And you'd also have to reroute the elevator pushrod... Or get a hollow motor shaft and run it through that
Mar 18, 2009, 06:36 PM
Registered User
DanT's Avatar
Quote:
Originally Posted by BustedBlades
Is anyone else's F&L too quiet? My F&L seems to be very quiet for how powerful it is. I can't really hear how much power I am putting into it, although I can see it accelerate like greased lightning. Even at full throttle it just hums a little. In a high speed dive at 1/2 throttle the wind noise is louder than the motor. I used an E-Flight stick mount on a 3/8"x3/8" stock hot glued into my fuselage. I am using a 10x6 APC speed prop. Maybe they are really efficient. I guess I need to try a wooden prop or something.

Hebert
I have that motor, but I don't run it on a Funder and Lightning. That motor is ok , but I like the Turingy 2213 /20 kv 1050 a lot better for this size of airplane!
The 2213 can make just about the same thrust!!!
My test prove it. Apc 10x 3.8 will make about 7,600 plus rpm's making about 38 oz of thrust!!
The C 35-30 kv 1100 will make 39.2 oz running a Apc 10x3.8 at 7,600 . So why carry the extra weight?
This setup should be running a speed prop. So you might try a Apc 10x 5 it makes more speed then the 10x7 because it turn a lot more rpm's ..About 8,400. or so!!
PS: that's about 40 mph on level flight.
I'm running about 60 mph on level fight!!
Mar 19, 2009, 01:21 PM
A real WingNut
j4ck4's Avatar
Hello Lee

Started another one of these last night.Got an outrunner to put on it this time, and have enough servos to run one for elev. and one for each aileron. I think this one will fly, the last just didn't have enough power with the brushed setup I tried to put on it. Hope to maiden this thing shortly.


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