Skymaster F5 questions
#28
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I have an SM T-38 that is ready for its maiden so I have read this thread with great interest :-)
Sitting on the gear my wing is about 1 degree positive AoA - though I think I will likely add the spacer anyway.
Anyone know the approx neutral position of the stabs with respect to the fuse? I am guessing with about 2 degrees of up incidence compared to the wing.
A Merlin 140 X for power ... 29 pounds dry.
Dave
Sitting on the gear my wing is about 1 degree positive AoA - though I think I will likely add the spacer anyway.
Anyone know the approx neutral position of the stabs with respect to the fuse? I am guessing with about 2 degrees of up incidence compared to the wing.
A Merlin 140 X for power ... 29 pounds dry.
Dave
#30
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HI ww2birds
The only mods that I have done are to make 2 braces for the main formers made of 1/4 inch ply and carbon and box the rear stab support with 1/8 ply
adds little weight but strengthens the assembly
I also added a 1/4 spacer to the nose gear to raise the nose slightly
Good luck
Ted
The only mods that I have done are to make 2 braces for the main formers made of 1/4 inch ply and carbon and box the rear stab support with 1/8 ply
adds little weight but strengthens the assembly
I also added a 1/4 spacer to the nose gear to raise the nose slightly
Good luck
Ted
#31
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A few years ago (5 years maybe more), Jed Jacobsen flew a fully scaled out F-5 with a scaled functioning canopy at Kentucky Jets. If I remember correctly, his plane even had an adjustable nose strut that could raise the aoa of the nose for take off. I believe the nose strut was controlled by air pressure. Does anyone have any info on who makes the adjustable strut for the F-5? If the strut is available, I think it would improve the rotation of this plane.
#34
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A few years ago (5 years maybe more), Jed Jacobsen flew a fully scaled out F-5 with a scaled functioning canopy at Kentucky Jets. If I remember correctly, his plane even had an adjustable nose strut that could raise the aoa of the nose for take off. I believe the nose strut was controlled by air pressure. Does anyone have any info on who makes the adjustable strut for the F-5? If the strut is available, I think it would improve the rotation of this plane.
#39
Join Date: Jun 2006
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Hi guys,
I have been following this thread and some of you may recall me asking for setup help a few months ago myself. I built my Skymaster F5e some years ago with an original AMT Pegasus in it. Then earlier this year I decided to revive it and fit an AMT Pegasus HP with a new radio setup, hence my questions then.
In the meantime I have again sorted my F5 and it is now right. Here is what I have;
- No stab modifications, except for mass balancing.
- Nose gear mount has 12mm spacers added to give the required AOA on take off and it works 100%.
- CG is at 110mm from wing LE (not the fuselage). About center of the airbrakes. You can go forward, but not back from there.
- Throws are: Ailerons - 15mm up and 18mm down with 15% expo, Elevator (neutral as per manual) - 45mm up and down with 15% expo, Flaps - 20mm take off and 30mm landing with 3mm and 8mm up compensation on elevator, Rudder - 40mm both ways with 15% expo.
I am am not an aggressive pilot and like to use my power in the verticals. The jet is fast and will hold your concentration. It comes in on approach with a nice nose up attitude.
Cheers,
Jan
I have been following this thread and some of you may recall me asking for setup help a few months ago myself. I built my Skymaster F5e some years ago with an original AMT Pegasus in it. Then earlier this year I decided to revive it and fit an AMT Pegasus HP with a new radio setup, hence my questions then.
In the meantime I have again sorted my F5 and it is now right. Here is what I have;
- No stab modifications, except for mass balancing.
- Nose gear mount has 12mm spacers added to give the required AOA on take off and it works 100%.
- CG is at 110mm from wing LE (not the fuselage). About center of the airbrakes. You can go forward, but not back from there.
- Throws are: Ailerons - 15mm up and 18mm down with 15% expo, Elevator (neutral as per manual) - 45mm up and down with 15% expo, Flaps - 20mm take off and 30mm landing with 3mm and 8mm up compensation on elevator, Rudder - 40mm both ways with 15% expo.
I am am not an aggressive pilot and like to use my power in the verticals. The jet is fast and will hold your concentration. It comes in on approach with a nice nose up attitude.
Cheers,
Jan
#40
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Jan, do you know what the AoA of the wing is sitting on the gear? As I posted above, I have a somewhat recent kit (about 2 years old) and it sits slightly positive AoA .. as I said above I am inclined to add the spacer but it would require removing a lot of the former that sits right above the NG air cylinder .. perhaps the later kits are modified for a different nose gear mount point?
Also, is it easy for you to measure or post a pic of what neutral on the stabs looks like?
thanks
Dave
Also, is it easy for you to measure or post a pic of what neutral on the stabs looks like?
thanks
Dave
#42
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I think the FB and SM F-5 are identical. I am now flying a FB F-5 and it does not leap off the ground if you set the C.G and flap correctly. The manual's C.G is too nose heavy, you will need to shift it back. I don't remember the exact C.G location, but I will get that to you in a day or two as I have packed it for BITW. We have 2 F-5 flying locally, and we got it figured out how to T.O smoothly without having a scale extendable nose gear.
Here are how, assuming you are using stock nose gear.
1. use a lot of flaps at take off, sometime I just use landing flap setting
2. move C.G backward ( I will confirm the setting later)
3. 1/2 through take off roll (about 100-150'), give about 1/2 up elevator and hold it there. This prevents the nose from dipping low and lightens the nose weight for rotation
4. Give a slightly up stick, about 1/8" up elevator, it will float up and take off at pretty scale angle.
I flew about 9 times at Whidbey jet like that and pretty happy with it.
By the way, the original stabs made by both companies are very weak, so we beef ours up with new stabs with 1/2 span full of carbon fiber, and PCB ribs, and 3mm anti-rotation pins that goes 1/2 chord length. They are rock solid like that. I am not sure whether both care compatible, but I think they should be.
I have a P160SX and it's a rocket ship when it goes. love it. Got one of my flying buddies sold on this.
Here is the link of the maiden. (George was flying it and got it dialed in for me. ,that take off rotation is the most abrupt one due to we were still dialing in the elevator neutral point. The future take off is as normal jet.
https://www.youtube.com/watch?v=RaBjMVKLeTg
Check out the 10:00 time frame for the setting and flight.
See the photos on the flap setting.
Hope these help.
Mike
Here are how, assuming you are using stock nose gear.
1. use a lot of flaps at take off, sometime I just use landing flap setting
2. move C.G backward ( I will confirm the setting later)
3. 1/2 through take off roll (about 100-150'), give about 1/2 up elevator and hold it there. This prevents the nose from dipping low and lightens the nose weight for rotation
4. Give a slightly up stick, about 1/8" up elevator, it will float up and take off at pretty scale angle.
I flew about 9 times at Whidbey jet like that and pretty happy with it.
By the way, the original stabs made by both companies are very weak, so we beef ours up with new stabs with 1/2 span full of carbon fiber, and PCB ribs, and 3mm anti-rotation pins that goes 1/2 chord length. They are rock solid like that. I am not sure whether both care compatible, but I think they should be.
I have a P160SX and it's a rocket ship when it goes. love it. Got one of my flying buddies sold on this.
Here is the link of the maiden. (George was flying it and got it dialed in for me. ,that take off rotation is the most abrupt one due to we were still dialing in the elevator neutral point. The future take off is as normal jet.
https://www.youtube.com/watch?v=RaBjMVKLeTg
Check out the 10:00 time frame for the setting and flight.
See the photos on the flap setting.
Hope these help.
Mike
#44
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Hi David. It's our custom made one for our F-5. we implemented all these enhanced stabs on our F-18, F-5, and F16 and other jets with full flying stabs that we buy from FB. You can order one sets from Jose at [email protected].
I will send him a notice and ask him to give you a quote and delivery time.
Mike
I will send him a notice and ask him to give you a quote and delivery time.
Mike
#47
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Here is an exposed view of the stabs we did for the MiG21 stabs. This is the same material and design structure that we have been using for all the stabs. We have done a lot of static and dynamic tests on these designs and it has about 5 times the strength, comparing to the old design. So far it's strong for only adding 15% of weight to the stabs.
Let me know what you think.
Mike
Let me know what you think.
Mike
#48
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Hi Guys,
Thanks for the waiting. I had a blast at best in the West, especially flying my desert camp F5 up against the best pilot in the world Ali on a F14! Luckily my Viper call sign lived up to the test.
The C.G is 4.5" from the wing's front section that merged with the wing (the black line on the photo). or approximately 60% from the front edge of the air brake.
Hope this will help. Also to reduce nose weight, I only fuel the top tank about 70% fuel. With the main tanks and 70% fuel on top tank, I am able to fly for about 7 minutes, with 40% fuel left on main with a JETCAT 160SX.
Mike
Thanks for the waiting. I had a blast at best in the West, especially flying my desert camp F5 up against the best pilot in the world Ali on a F14! Luckily my Viper call sign lived up to the test.
The C.G is 4.5" from the wing's front section that merged with the wing (the black line on the photo). or approximately 60% from the front edge of the air brake.
Hope this will help. Also to reduce nose weight, I only fuel the top tank about 70% fuel. With the main tanks and 70% fuel on top tank, I am able to fly for about 7 minutes, with 40% fuel left on main with a JETCAT 160SX.
Mike
#50
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I have a Skymaster F-5 that recently underwent its first test flight. Takeaways:
1) With the stock nose gear from Skymaster, the jet does not want to rotate. Even taking off with full flaps doesn't seem to help. I bought an extendable nose gear from Matrix (referenced earlier in this thread) and am working on the install now. One problem I have is that the Matrix gear is one way only; that is, air pressure extends the gear, but you can't use air to collapse it again. That would be fine except for the fact that when the gear is extended, it won't fit into the wheel well unless you open the wheel well up more. I'm playing with springs right now in hopes of modifying the gear for air-down/spring-up operation.
2) I built and installed a spar brace (see picture) after seeing a similar jet go down at Jets Over Kentucky a few years ago when its wings folded in flight. I know of at least one other F-5 owner who has since gone back and installed a spar brace just to be safe.
Hope this helps. If anyone knows of someone who sells extendable nose gear for this F-5 that operates with air both ways, let me know because I'd be tempted to try it. For the record, John at Matrix has been extremely helpful, even offering to take the gear back if I can't get it to work. It's a beautiful piece of machining, so I'd much prefer to use it if possible.
1) With the stock nose gear from Skymaster, the jet does not want to rotate. Even taking off with full flaps doesn't seem to help. I bought an extendable nose gear from Matrix (referenced earlier in this thread) and am working on the install now. One problem I have is that the Matrix gear is one way only; that is, air pressure extends the gear, but you can't use air to collapse it again. That would be fine except for the fact that when the gear is extended, it won't fit into the wheel well unless you open the wheel well up more. I'm playing with springs right now in hopes of modifying the gear for air-down/spring-up operation.
2) I built and installed a spar brace (see picture) after seeing a similar jet go down at Jets Over Kentucky a few years ago when its wings folded in flight. I know of at least one other F-5 owner who has since gone back and installed a spar brace just to be safe.
Hope this helps. If anyone knows of someone who sells extendable nose gear for this F-5 that operates with air both ways, let me know because I'd be tempted to try it. For the record, John at Matrix has been extremely helpful, even offering to take the gear back if I can't get it to work. It's a beautiful piece of machining, so I'd much prefer to use it if possible.