Fokker D7 Wing for 2 Seater

franzkait · 19 August 2006, 11:11 AM

2 seater Wing with 100 liter tank

franzkait · 23 August 2006, 03:42 AM

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franzkait · 23 August 2006, 04:10 AM

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Maxim08 · 24 August 2006, 03:35 PM

franzkait,
Are there four tanks that I see?
Did you consider the axle box tank(s) fo this application?
Regards,
Maxim08

franzkait · 24 August 2006, 03:47 PM

jes, there are 4 tanks. to have the tank in the wing is better compare this dangeres axle tank. There is no original war time D7 today with the original axle wing , I think you know the reason

Machinbird · 26 August 2006, 10:20 AM

Franzkait. I'm glad to see someone tempering the exact replication of previous aircraft designs/systems with a little safety common sense. It looks like you even left enough room in the center section for a BRS chute.

scott5952 · 26 August 2006, 08:05 PM

Maybe you can help me by answering a couple of dumb questions Franzkait.

I am designing a replica Dr1 and was considering actually using a "stub wing" fuel tank like the latter D7s (running out of room in the fueslage). When you say it was dangerous, what type of problems did they have with it.. (very curious here,,, as I am alergic to fire!)

Where did you get those tanks, they look great!

franzkait · 27 August 2006, 03:37 AM

look how many inches you have between the ground and the axle wing, to have the fuel tank in the top wing is much saver. We made the tanks, this tanks are from gfk

Machinbird · 27 August 2006, 07:51 AM

To add to what Franzkait has said, answer the question," How will the fuel be transferred out of the axle wing?" If you use a common method of the period (air pressure) just imagine what might happen if you take a sudden swerve and take out a runway light. Suppose the light tears a hole in the bottom of your pressurized axle fuel tank. Where does the fuel go? Are there any ignition sources?
Run the same scenario with an electric fuel pump. suppose the pump is energized at the time of the runway excursion and the wiring is damaged....
OK, I recognize that proper systems operation will mitigate some of these hazards, but why place fuel tanks in harms way?

For Franzkait, GFK is not a common term on the US side of the pond. The references I have found refer to a glass (or carbon) fiber reinforced plastic that is injection moldable. Is that what you are referring to?

scott5952 · 27 August 2006, 08:53 AM

OK, I can definetly see an issue if the tank was pressurized! (I had often wondered about that when reading about the EIs with pressurized fuel tanks - one bullet and and instant cloud of bang!)

I don't think it is an issue now, after seeing those nice wing tanks and having a big empty wing - I think I know where I am leaning towards putting them now.

I had orginally thought of putting them in the middle wing, but rejected it because when they were full they tended add a weird vibe mode around 8hz that was wing torsionally bending to a higher angle of attack coinciding with tail bending upward. Not unlike fire, static divergence also scares me! Also, all that mass outboard in the wings does not help with spin recovery.

Maybe I will just copy Franzkaits upper wing installation and stop sweating the details!!