Build Log F-35B Lightning II VTOL - Scale composite build!!!

[bigwood212]

i want one

[capt]

Here is some real techie stuff on the F35, interesting because they talk about the CG location and calculate where it should be.

http://www.aoe.vt.edu/~mason/Mason_f/F35AndrewsS03.pdf

[matthew73]

Please give us more. I can appreciate the time and cost spent on this project. Keep up the good work. Is there any chance of some basic updates, thoughts, ideas etc to keep this thread alive

[newbieflyer]

awesome scale build, 9/10.

but its very hard to get that thing in the air due to its weight.

static thrust is different from thrust itself.

[derk]

Originally Posted by vertigo-rc

I somewhat just answered my own question just as I posted the previous message!! It seems I was assuming that the F-35B was a flying wing! I neglected to take the tail surface area into account, which has it's own aerodynamic center which will shift the neutral point of the whole aircraft (and thus the allowable CG position) rearwards!!! I wonder where those roll posts lie with respect to the CG now????

i think that having the roll fans more rear would help make an offset for vectoring losses of the rear fan. the amount of thrust they make could be tuned to match the losses and the distance from the cg could be calculated into this as well.

this is a great build so far by the way, cant wait to see it all together

[QieFeng2.4G]

i do not agree your idea of roll contral system. as we all know,when the fan truns, the momentum is very large. the rpm will not be contraled immediately. increase the gyro`s sensability still uesless. i think the best way is use sevros to contral the acreage of fan`s hole. that will make the roll proformence better.

[cray2602]

Hope this isnt the end of this thread. No posts from builders for about 6 weeks. I was looking forward to watching this one do it right.

[v22chap]

He probably has some company after it and can't post any more cool stuff ,,, hope he keeps at it .

[G-force237]

Hey, Sorry to not post an update in a while. my internet dropped out for two weeks, and now I am back at school. I dont have time now, but I will update this thread to where the project currently lies. so more pics to come.

But on a quick note. Having the 'puffers' rear of the cg did not have us too concerned about inducing a pitch/roll coupling from roll controll inputs. The thought was that for a roll input, one edf40 would spool up and the other would spool down keeping the net thrust roughly equal. This means there would be no moment created about the pitch axis while there would be one created along the roll axis. The only concern I could see would be if the fan spooling down decreases its thrust at a different rate than the one spooling up increases in thrust.. in any case if this were so, I would think they are still close enough to the cg and the change in thrust output would be so small that it would seem any pitch moment created would be negligable.

I am glad to see there is still interest in this. We are going to try to pick this back up over winter break.

[jimbob00]

g-force, your project is *awesome* and i think while theres not much thread activity everyone would really like to see it finished.
And when I say awesome I don't mean, like "oh look a new parkzone plane its awesome". No, this project is really awesome, one of the bests, really.

Keep going!

[cray2602]

Glad to see its still a work in progress and not shelved due to problems.

I have had pitch coupled with roll problems with one experiment i did that had two lift fans about where your roll fans are, no way to fix it. But since your roll fans arent produceing nearly the amount of thrust as your two lift fans i doubt you will have much trouble with the pitch changeing with roll input. It absolutely will affect it if the fans arent exactly centered on the CG, its only a matter of how much and is it enough to be a problem.

[nadine]

Hi !!!! Ia Ma Interested To Build My Self Something Like That ,but 3 Fans 64.....you Could Post ,please ,what Settup And How You Connect All 4 Edf?a Schemme Wiring!!bye

[Angry_Monk]

Im pretty sure this is so cool that its actually illegal....

seriously, this is amazing. awesome work.

[NuttyPro67]

NICE! You guys have the BEST F-35 VTOL attempt I have seen to date. I see only two issues you may have and want to be mindful of:

First off, that framework and wiring in the ducting is probably going to destroy ATLEAST 20 percent of your thrust...Which is a shame because that leads to the second issue. Once you get the plane out of VTOL mode and into CTOL mode, you might not have enough power to keep aloft.

Just think, you've got a 3 pound plane with motors pushing 5+ pounds of thrust max, but that back motor may only represent 2 pounds of that thrust. Get some forward airspeed and cut off your other 3 pounds of thrust, now you have a terrible power to thrust ratio. Just something to keep an eye out for, but I'm sure you've already thought through all this.

Good luck!

[TermIInatoR]

g-force, this is a very ambitious project and I love it! It's sooo coool!