Strykaas

olnico,
that is an awesome a4 (rarely seen on rcu), I love it [8D]

GJr.

My Feedback: (3)

The old yellow A/C A4 (especially the scale wing) had a tendency to snap out of turns without warning. It was the first fan jet I owned and flew. The first time it happened I could not figure out what was going on. After the second time, I decided to talk to Bob Fiorenze, the head Yellow guru of the time. Bob told me that I was pulling to much elevator in the turn causing, a high speed stall. The solution was to not bank too deep in the turn or if so roll back to neutral asap. The other recommendation was not to pull too much elevator when the sircraft was banked excessively.
One thing that compounded the situation for me, was that I was racing Q500 at the time and flew the A4 too much like a Q500 plane. As soon as I eased off the bank angle and/or elevator, things were great. It was one of the best landing jets I had. I should have realized what was going on sooner, as I had a scale Spitfire that did the same thing about 15 years earlier. It would blank out the elevator at high speeds in highly banked tight turn.
It seems that it just may be a characteristic of the A4, no matter what kit, that you have to learn and deal with, just like other designs.

olnico

Hi Eddie,
The first two flights were 4 minutes each only due to the massive xwind on that day ( a bit stressful for a maiden ).
I had a AR9000 and Sensor switch II with 2 1300 Lipo batteries. That was a little undersized to my appreciation.
This is why I switched to the AR9100.
The little flights I did were the same as the last one. Very stable, nice handling. Not too sensitive, not too slugish.
Tam did a good job on the setup data.

olnico

Thanks to everyone for your support and comments. It is a real relief to read nice posts about this hard job I did for 4 months.
Just to let you know, this is not all lost: I have made silicon molds of all the scale parts, antennas aso. I am making a converion kit to the A-4M...

Yann

Hi Oliver,
It took me few years to complete my A4 with the parts you did for me (light bulbs, antennas...).
Everything is a tight fit in this plane but it is very well designed. Congratulations to Tam.
It is the first time I change so little from the original design.
I still have to paint the wing tanks and bombs, add the lighting system unit and balance the plane on the CG point.
I took a different route to scale it up a little, but I still followed your steps. It was a good thing I saved all your pictures on my computer back then...
Eventhough far from prefect, I'm pretty happy with the end result.
Haven't had time yet to weight the bird. Turbine will be my good old hand start Wren supersport.
Regards,
Yann

Yann

Some more pics...

Yann

Finally took the time to balance the bird. Had to add over 300grams of lead in the nose to balance per the book. Total dry weight is 9100 grams (20lbs).
Bombs and wing tanks are also painted. Need to find time to fly it now...

olnico

Very nice build Yann. Congratulations.
Make sure you use a long runway for the maiden. With a similar weight and a P-60 I had some long takeoff roll.
A little bit of flaps does help for sure.

xgnsxgnhu

Yann

Thanks for the hint Olivier. I have a 200m long runaway. It should be enough with a wren supersport pushing around 90N...
Do you advise to use control throws as per the book? same for CoG?
I'll see if I can manage to have a video footage of the maiden...

bri6672

My Feedback: (6)

I have an turbine version powered by edf (19lbs of thrust on the stand) mine has an AUW of 21lbs and it flys great at that weight.

control throws per manual are good but be sure you have max mech advantage on the elevator and rudder! Be sure you are at the factory cg or back and not in front, the center of the spar is conservative and mine didn't want to pull out thru the turns as well when it was nose heavy!

olnico

200 m is not that long, actually. Make sure that the angle of attack of the wing is positive all the way to the tip when the plane is sitting on the ground with full tanks. If not, consider using a stiffer nose wheel spring or offsetting the strut a bit down ( which would require grinding a bit the rear of the gear bay lip ). You'll definitely need flaps.

bri6672

My Feedback: (6)

With the air pressurized the AOA should be fine. I fly mine off of 600' no problem. I use takeoff flaps and full flaps on landing. With tams recommendations in the manual there was 0 trim changes with flaps.

Here is my maiden:
http://youtu.be/bocpQqtEX14

Yann

I'll make sure I always have positive AoA on the ground. I'll use half flap deflection for take off.
Nice landing bri6672. your A4 seems to come in a little hot.
Thanks for the hints guys. I'll let you know how it goes.

bri6672

My Feedback: (6)

That at was just the maiden, 6 flights later and she lands much slower. I always land hot on the maiden.

Yann

Makes sense. Nice landing anyway.

Yann

I managed to fit the drop tanks and check AoA.
When plane turned off, AoA is just above 1°. When plane turned on (nose Wheel jacked up) AoA is 2°.
It should be enough for easy take off.
I will not fly the A4 with drop tanks as ground clearance seems pretty small...
I also test ran the engine OK (Wren supersport).

erbroens

Looking great Yann, congrats! wonder as it would be difficult to modify the landing gear, reducing slightly the wing pylons would allow you to fly it with the tanks.

Yann

Well, there is no easy way to have longer main legs. You'd have to either put larger wheels or put stiffer oléo springs.
A longer nose leg would have to retract in the nose cone. One thing I noticed though is the fact that those wing tanks are way out of scale.

erbroens

yes they are a bit fatter than they should precisely near the ground...anyway, don´t mind that, your A4 looks great, with ot without tanks.

Yann

Thanks erbroens.

RAPPTOR

My Feedback: (41)

Hi. What is too heavy?? Lol ---wet