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F-8E crusader.

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Old 06-18-2017, 05:27 PM
  #101
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Awesome!
Great work Oli.
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Old 06-19-2017, 09:52 AM
  #102
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Thanks!
I am now working on the instrument panel and side panels...
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Old 09-09-2017, 09:03 AM
  #103
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Here is a short video of the Crusader prototype maiden. It was quite tail heavy and quite pitch unstable. However after getting the trims dialed up, she flew in nicely back to the runway.
I will pull the CG 1/2" forward for the next flight and she should be on rails!

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Old 09-09-2017, 10:46 AM
  #104
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Congratulations Oli !
Do the elevators change center when wing is raised ?
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Old 09-09-2017, 02:08 PM
  #105
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Quote:
Originally Posted by DelGatoGrande View Post
Congratulations Oli !
Do the elevators change center when wing is raised ?
Thanks!

Yes. By about 1/4".
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Old 09-09-2017, 04:45 PM
  #106
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Gorgeous Oli. She looks like she was a handful there for a bit.
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Old 09-09-2017, 10:23 PM
  #107
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Great work on a difficult aircraft to model ......
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Old 09-10-2017, 03:19 PM
  #108
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Quote:
Originally Posted by smaze17 View Post
Gorgeous Oli. She looks like she was a handful there for a bit.
Indeed!!!
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Old 09-10-2017, 04:20 PM
  #109
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Looking forward to follow on flights.
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Old 09-10-2017, 05:12 PM
  #110
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WOW - the "True Gunfighter" comes to life. Chic
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Old 09-11-2017, 03:01 AM
  #111
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Quote:
Originally Posted by skybuster97 View Post
Great work on a difficult aircraft to model ......
Thanks!
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Old 09-11-2017, 03:01 AM
  #112
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Quote:
Originally Posted by yeahbaby View Post
Looking forward to follow on flights.
Me too!!!!
I will resume flight testing after Jet Power.
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Old 09-11-2017, 03:24 AM
  #113
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Here are the data/ maneuvering speeds I recorded on the first test flight:

Takeoff weight with working wing incidence system on 2 servos: 18 kgs/ 40 lbs
Channels used: 16
Servos: 12
Engine: B-140F
Fuel embarked 4 liters/ 135 fl.oz

Configuration: wing up 10, flaps down 10 degrees, slats down 10 degrees.

Weather: OAT 43 c/ 104 F
QNH: 1000
Wind 30 degrees offset/ 10 km/h - 8 kts
Density altitude: 4000 ft

Rotate speed flaps 10: 55 km/h or 35 mph
Liftoff speed flaps 10: 60 km/h or 37 mph
Pattern speed flaps 10: 100 km/h or 62 mph
Approach speed flaps 10: 80 km/h or 50 mph
Touchdown zone speed flaps 10: 65 km/h or 40 mph
Stall speed: 50 km/h or 31 mph

Takeoff run: 100 yards/ meters.
Landing run: 100 yards/ meters.

Elevator authority too high at 20 degree. Reduced to 15 degrees improved stability.
Aircraft very stable on final. Approach path angle is controlled by thrust.
Thrust required with flaps 10 on a 3 degree path: 50% to 40%
Behavior in flare; late thrust reduction required, sinks as soon as the thrust is removed, flare on elevator very limited due to tail clearance.
In other words, the plane lands pretty much flat.

This prototype plane is close to production definition with 50% carbon fiber structure.
All internals are carbon/ airex, except for the gear plates and gear/ wing axle bulkhead.
Wings are glass/ airex laminate with carbon/ airex internals.
Fuselage is a mix of plain glass and carbon/ airex laminate.

I am still working on reducing the weight of the airframe, mostly on the landing gear, at this stage by using extensive 3D printing hybrid construction. Weight reduction is a real challenge on this project.
I also had to extensively work on the internal airflow. The inlet duct configuration generates a lot of venturi effect. It took 7 iterations of the inlet duct/ pipe diameters/ area law modification/ carbon fiber reinforcement to achieve a good operation of the inlet.

The amazing thing about this inlet is that it sounds the same as the real one and generates the same fogging/ condensation effect at the lip. This was confirmed to me by a French Navy Crusader instructor who attended the engine/ ground tests with me. I have been unable to capture this experience on the camera unfortunately but it is immediately evident when standing by the plane.

Last edited by olnico; 09-11-2017 at 03:35 AM.
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Old 09-11-2017, 10:02 AM
  #114
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Quote:
Originally Posted by olnico View Post
Here is a short video of the Crusader prototype maiden. It was quite tail heavy and quite pitch unstable. However after getting the trims dialed up, she flew in nicely back to the runway.
I will pull the CG 1/2" forward for the next flight and she should be on rails!

https://vimeo.com/233120379
Man Oli, "quite tail heavy and pitch unstable"? You sometimes have a gift for understatement! When I saw that takeoff I was wondering if you'd get it back down in one piece, really nice job of flying!

It's 'gonna be a great model.
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Old 09-11-2017, 05:40 PM
  #115
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Quote:
Originally Posted by Zeeb View Post
Man Oli, "quite tail heavy and pitch unstable"? You sometimes have a gift for understatement! When I saw that takeoff I was wondering if you'd get it back down in one piece, really nice job of flying!

It's 'gonna be a great model.
Lol, thanks Gary.
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Old 09-11-2017, 07:46 PM
  #116
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Can't wait to fly one! One of my favorite airplanes ever!
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Old 10-03-2017, 05:39 PM
  #117
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Some update on the Crusader.

I have had many flights with the plane now. I am in love with it. It is absolutely stunning in the air. Super stable, an enormous presence, extremely gentle and well mannered at low speed.
Here is an extract of the operations manual I am writing for it:

Takeoff

. Use the takeoff configuration for optimum results. This ensures great aileron authority at low speed and a reasonably short takeoff roll.


. Apply brakes when aligned to the runway center line.

. Apply 50% power.

. Release brakes and apply 100% thrust.

. Steer the plane on the runway center line. Apply ailerons into the wind if required to keep the wings level.

. Takeoff liftoff speed at 18 kgs/ 40 lbs: 72 km/ h, 45 mph

. Takeoff liftoff speed at 19 kgs/ 42 lbs: 82 km/ h, 51 mph

No up elevator is required for liftoff or a very small amount. This is due to the augmented wing angle of attack

. Typical takeoff distance on asphalt: 100 m/ 100 yd

. Retract the gear after liftoff.

The plane will tend to oscillate on the roll axis initially, just like the full size version. This roll oscillation will be more pronounced if the ventral fins are not fitted ( replica of the early F8U1 A to E )

. Keep full power till passing the speed of 115 km/h, 72 mph.

.Then retract the flaps to clean if required.

Typical landing pattern and technique:

Proceed with a gear extension low pass. Verify all 3 gear down. Select your controls to extend takeoff configuration.

Come on your downwind leg with the recommended speed.

. Recommended downwind speed: 135 km/ h, 84 mph in takeoff configuration





On base leg, start descending the plane to a 3 degree slope and reduce the speed.

. Recommended base leg speed: 119 km/ h, 74 mph

On final reduce further to the recommended speed. The plane attitude should be to about 6 degrees nose up. Thrust should be about 50% of max thrust.





Takeoff configuration landing:

We recommend using takeoff configuration for landing in turbulent air/ crosswind conditions/ wind speed above 15 kts. This is because the plane has more aileron authority in this configuration.

. Recommend final approach speed at 18 kgs gross weight: 80 km/ h, 50 mph

. Recommend final approach speed at 19 kgs gross weight: 90 km/ h, 56 mph

Bring the plane to the threshold and slowly reduce the throttle.

. Recommended over threshold/ flare speed at 17 kgs gross weight: 60 km/h, 37 mph

. Recommended over threshold/ flare speed at 18 kgs gross weight: 72 km/h, 45 mph






Here are a few pictures of the airframe and some details about the design:

The wing bay with the carbon fiber molded actuator plate, designed to fit above the inlet duct, as well as the Jeti CB 400 distribution box.




The rear wing tilt hinges. The plain Finnish birch aircraft certified plywood bulkhead is a solid piece cut as an "O" shape around the inlet duct to ensure tilt stability of the wing. A large carbon fiber tape reinforces the skin at this area. The CNC cut hinges are designed to withstand 400 lbs of load each.



I spent a lot of time to carefully design the inlet duct. It is a 100% clean aero shape all the way to the carbon fiber bypass! This duct also follows the area rule with a continuous 4% increase. The inlet lip is sharp, like the real plane. As a result, the inlet "sounds" like the real one when the engine is running. One can see a condensation ring at full thrust on a wet day like the real one!




The nose strut after weathering look absolutely gorgeous. Its is scale to 1/10th mm. The tire is custom 3D printed from rubber and 100% scale as well. This material has been tested in the hottest conditions and runs really well from -20c to +45c OAT!



The main gear, wheel, tire and brake assembly are also 100% scale!



The carbon fiber bypass and in-house manufactured stainless steel pipe work really well together. The pipe is made from 100% USA produced materials, including the highest grade stainless steel available on the market. I have opened a small pipe production line for our kits and will soon produce a few more custom pipes for 3rd party manufacturers.


Last edited by olnico; 10-03-2017 at 05:43 PM.
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Old 10-03-2017, 07:22 PM
  #118
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Simply awesome! Well done. Video?

David S
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Old 10-03-2017, 09:13 PM
  #119
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Quote:
Originally Posted by David Searles View Post
Simply awesome! Well done. Video?

David S
Thanks bud. Sure, as soon as I find a camera operator!!!!!
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Old 10-04-2017, 03:39 AM
  #120
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Amazing model! Great to see so much design and testing involved compared to many ARF's these days. Just out of interest, is there not a very high load on those servo's adjusting the wing incidence? They are holding together with the aft hinges the full wing load, during a high g-load turn that's a lot of force on those servo cases and output splines. It would be nice to see some CNC guide tracks that lock the wing mechanically in it's extended and retracted position similar to a retracts mechanism to off load those servo's.

Arjan
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Old 10-04-2017, 06:41 AM
  #121
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Absolutely gorgeous. This aircraft will be a must have IMHO.

S
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Old 10-04-2017, 10:15 AM
  #122
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Quote:
Originally Posted by arjan2856 View Post
Amazing model! Great to see so much design and testing involved compared to many ARF's these days. Just out of interest, is there not a very high load on those servo's adjusting the wing incidence? They are holding together with the aft hinges the full wing load, during a high g-load turn that's a lot of force on those servo cases and output splines. It would be nice to see some CNC guide tracks that lock the wing mechanically in it's extended and retracted position similar to a retracts mechanism to off load those servo's.

Arjan
Good point. Here is how it works.
The center of lift is actually quite close to the hinges. Most of the load is concentrated there.
The servos get to hold about 30 kgs of weight each at 10 Gs. This is within the specs of the servos used ( 30 kgs.cm ).
In both the down and up position, the link is passing close to the spline axis. So there is little load on the servo motor ( about 10 kgs.cm ). Most of it is taken by the output bearing and servo casing.
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Old 10-04-2017, 10:44 AM
  #123
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Quote:
Originally Posted by olnico View Post
Good point. Here is how it works.
The center of lift is actually quite close to the hinges. Most of the load is concentrated there.
The servos get to hold about 30 kgs of weight each at 10 Gs. This is within the specs of the servos used ( 30 kgs.cm ).
In both the down and up position, the link is passing close to the spline axis. So there is little load on the servo motor ( about 10 kgs.cm ). Most of it is taken by the output bearing and servo casing.
Hi Olnico,

Thanks for your explanation! If you don't mind me asking further: if the servo is 30kgs/cm, with the servo arm length of what looks like around 25mm, that gives the servo arm only a maximum hold power of around 12kgs. I can understand it would be very unusual to move the wing in a high g-load, but still i find these servo loads of 30kgs very high, both on the spline and the plastic case. I would love to see a more mechanical solution with a linear actuator/screw jack. Not meant to criticise, i love the model and it's on my wish list

Rgds, Arjan
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Old 10-05-2017, 03:43 AM
  #124
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Quote:
Originally Posted by olnico View Post
Good point. Here is how it works.
The center of lift is actually quite close to the hinges. Most of the load is concentrated there.
The servos get to hold about 30 kgs of weight each at 10 Gs. This is within the specs of the servos used ( 30 kgs.cm ).
In both the down and up position, the link is passing close to the spline axis. So there is little load on the servo motor ( about 10 kgs.cm ). Most of it is taken by the output bearing and servo casing.
Also Oli......if servo was to fail the breakout torque of the servo is probably enough to keep the incidence fixed where it is, and it's proven that the F-8 will fly quite well at any wing incidence level....so just fly it and land as soon as practical.
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Old 10-05-2017, 07:03 AM
  #125
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Quote:
Originally Posted by arjan2856 View Post
Hi Olnico,

Thanks for your explanation! If you don't mind me asking further: if the servo is 30kgs/cm, with the servo arm length of what looks like around 25mm, that gives the servo arm only a maximum hold power of around 12kgs. I can understand it would be very unusual to move the wing in a high g-load, but still i find these servo loads of 30kgs very high, both on the spline and the plastic case. I would love to see a more mechanical solution with a linear actuator/screw jack. Not meant to criticise, i love the model and it's on my wish list

Rgds, Arjan
Some more insights into this:

The plane is 18 kgs to 19 kgs wet at T/O.
Under 10 gs, the load bearing is 190 kgs.
The center of lift of the wing is 2/3 towards the hinge.
The hinge bears 127 kgs, the servos 63 kgs.
So 31.5 kgs of load per servo to be precise.
modern high spec servos are rated at 30 kg.cm. JR is certifying the used servos for a load of over 30 kgs at a 1 cm lever arm. This means that the spline and casing take the load laterally without problem.
In effect, I have tested both NX8931 and NXB8921 servos under 60 kgs lateral load without any problem on the bench. No large casing structural deformation, no clacking noise around the bearing area.

Because the pushrod is passing 3 mm away from the servo spline in the down position ( arm nearly vertical ), there is only 10 kg of torque applied to the arm at max load. This is far from a simple design and I spent hours on the structural analysis software to size everything to specs +50%. What is tricky is not the servo torque. It is the fact that the full 30+ kgs apply to the spline/ arm/ attachment and a full 63 kgs to the bracket/ fuselage.

Note that I am also working on a fully redundant servo gearbox design actuated by 2 JR NX3425 servos with two large 12 mm axle, quad bearing support ,1;5 ratio and integrated lock. However this will be an option and it looks like it will cost about 400 USD.
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