RE: Skymaster F-4E phantom
 

Hi,Ehab

the intakes with Fuel Tank cell for F-4 twin is ready now,

Please make the list to me for which one do you want?

I will send all parts with drop tanks and missiles for f-4 to you next week,

Best Regards

Anton

RE: Skymaster F-4E phantom
 

Hello David S
I have a F 4 E from SKYMASTER
I was trying to take off last saturday but model would not lift off after 250 meters 300yds model seems to stick to the runway
CG is at 285mm up elevator is at 60mm neutral at 10mm up down 55mm Turbine used is a nexus Simjet 36lb trust what am I doing wrong may be you can help me
regards
Andreas B

RE: Skymaster F-4E phantom
 

Hello Andreas,

my Skymaster F4-C CG is 290 mm, elevator is at 60 mm up and down. and my model lift off in 80 meters. Look at the pic for neutral elevator.my turbine is a Frank Turbine 17,1 kg.


best regards

Michel

RE: Skymaster F-4E phantom
 

Ok after about 50 flights on this phantom, I've discovered two VERY BAD HABITS!!!!!

1. If the flaps are deployed with the nose pointing down, the elevators are completely negated. This causes a very SCARY earthward decent that CANNOT be reversed until the flaps are placed back to neutral.

2. ON BASE AND FINAL, KEEP THE NOSE UP!!! If the nose is allowed to point down with the flaps deployed, there is a critical angle (and I'm sure it is a very small difference in living or dying here) in which the elevator is blanked out by the flaps. (I had 80mm of elevator travel. I had to grind away to give my self this much.)

Once again, if the nose gets to this critical angle, she will NOT respond to your elevator. So keep the nose up, when flaps are deployed.

Raf

Raf

RE: Skymaster F-4E phantom
 

Hello Raf,

thank you for the information, i'll test this configuration for the next fly. For take off the flaps are down at 20 mm and for landing 60 mm, and you?

Michel

RE: Skymaster F-4E phantom
 

Hello Michel

Thank you for the info
what is your all up weight ?
and do you not finde that the model sticks to the runway I found with the amount of down trust of the of the trust pipe that it forces the nose down and changes the angle of atackof the main wing to a negative aditute so you recon if I give the elevator about this much of up as per your photo that should me to sort out the problem. Doyuo use your flaps on take off? and how much what about landing how do you find it?
regards
Andreas

RE: Skymaster F-4E phantom
 

Hello Raf
thank you for the info
regards
Andreas

RE: Skymaster F-4E phantom
 

Ok, Cool!!!!

RE: Skymaster F-4E phantom
 

Your take off configuration sounds right at about 20 mm, I don't remember my landing configuration, but I remember I had to turn it down from what the instructions say.

Raf

RE: Skymaster F-4E phantom
 

Hello Andreas,

15,5 kg dry more 4,8 kg kero. I gave a thicker oil in the nose gear to raise the nose of the plane, with rolling the incidence remains positive, and the flaps is down at 20 mm for take off. Take off, fly and landing, the neutral position of the elevator is the same. Look at the pic for the incidence( the angle of atackof )
Sorry for my bad English

regards
Michel

RE: Skymaster F-4E phantom
 

Hello Michel
thank you this is exactly what I think is the problem that the nose is to low on roll out as the model picks up speed it forces the nose further down, so raising the nose must certainly do the trick. how do you change the oil in the nose leg?

thank you for your help
PS my french writing would not be as good as your english
regards
Andreas

RE: Skymaster F-4E phantom
 

Hi Andreas, just saw your post here, I just sent you an email with some ideas. I think that besides the positive AOA the down thrust also creates an issue. This should be as minimun as posible. But not so little that it will affect the stabs.

I also saw the same behaviour that Raf coments on landings if the nose goes down to a certain degree it will be very dificult to pull it up. This changed a lot by decreasing the pipe angle. After the midification the F-4 flew way better.

For the people that don't know what we did is mount the turbine hanging from the mount instead of over it, we also add some washers to get the correct angle on the turbine and pipe. Remember that the engine and pipe must be aligned. We where able to had less down thrust this way. After the mods the F-4 took off much earlier and landed much easier.

Michel

RE: Skymaster F-4E phantom
 

Hello Michel D. and Andreas,


I agree with you Michel D. the angle of the turbine and of the pipe must also give a diving moment; But the very special profile of the elevator must correct it partly.
For the nose leg, the weel up, unscrew the suspension ( i dont now the word ) in French: Compas

Best regards

Michel J.

RE: Skymaster F-4E phantom
 

I have quite a bit of downthrust in mine ... I couldn't lower the engine as it sits nicely in the intake when mounted to the top of the mounting rails. I get no pitch change with throttle, so feel the downthrust is appropriate. I really don't think this is your problem as mine comes off OK without any flaps.

What is the weight of your plane? Did you mount the nose gear to the bottom or top of the nose gear mounting plate? Can you provide a reference point for the front of the stab at neutral? Are you taking off from a grass or asphalt runway? Temp and altitude? Are you sure the engine was completely spooled up and putting out full power (checking RPMs on GSU?). What does your arcraft weigh? Did you make any modifications to the kit? I definitely agree the CG should be at 290 mm ... that is where I am flying mine and it works well.

RE: Skymaster F-4E phantom
 

Hi Kith
my dry weight is 16.1 kg
I fly of grass runway
and my Nexus was on full rpm 118000
nose leg is mounted on nose
I had to put 2lb of lead in nose to balance it at 290 mm
how do you increase the spring in nose leg it oil filed put there is no blead screw as per the instructions from skymaster
I pulled it apart and added more oil it did make it harder .
regareds
Anderas

RE: Skymaster F-4E phantom
 

Your weight is fine, almost exactly what mine is. I have a little less lead in the nose ... about a pound and a half. Don't know how good your grass strip is, but that might be part of the problem. I am getting a run of at least 100 meters, and that is off smooth asphalt. Sounds like your nose gear is mounted OK. Check your stab. It should be about 15 mm above dead neutral at the inside trailing edge. Make sure you have at least 35mm of travel available in addition to the 15 mm of up trim. I had to trim the fuselage a bit to get enough up elevator.

I did not modify my nose strut at all.

One other thought .... make sure your wheels are spinning absolutely freely. It is easy to get the nuts just a tad tight and the wheels will be stiff. Check to make sure you don't have too much toe in, and that the plane rolls freely on concrete.

You could also try moving the CG back to 300. Remove about 5 ounces to move the CG back 10 mm, assuming your lead is all the way up in the nose.

RE: Skymaster F-4E phantom
 

Had to post this. Looks so damn real in the air.

RE: Skymaster F-4E phantom
 

Nice pic Keith, it looks really great...;)
We recentlly added some lights to the F-4 from Flumodellbau, it looks awesome....[X(] You should try it, after seen the lights work at plain daylight I ordered a full F-4 scale set for my new Black Bunny also. The F-4 has some very interesting lights.

Todd is the dealer in the US...

Michel

RE: Skymaster F-4E phantom
 

What is the current thinking as to why significant up trim is needed for straight and level flight?

Spectacular photo Keith.

RE: Skymaster F-4E phantom
 

Michel

Here is Thunder Bird color scheme ,

Best Regards

Anton

RE: Skymaster F-4E phantom
 

Very nice Anton.....:D My Black Bunny is almoust done, I expect to do the maiden these Saturday...;)

Michel

RE: Skymaster F-4E phantom
 

Hello All,

a new method for the little door of main gear.

Best regards
Michel J.

RE: Skymaster F-4E phantom
 

Great idea harpoonlightning, no rubber bands neither springs just another little piston, exellent, take care...

RE: Skymaster F-4E phantom
 

Exelent Michel J., very nice setup....;) Acrored did a nice mod to mine but haven't been able to test the new design.... I will post pics when tested...;)

Michel D.

RE: Skymaster F-4E phantom
 

Ok I have had over 6 flights with this new setup and it works great. Basically you connect a Z type wire from the door to the trunion and you use the trunion to open and close the small door. Works great...

Michel...