FMS P-51b Main Wing Spar

[JFandL]

Hey Guys,

I emailed FMS 3 times and they did email me back which they have never done before. They think I have a bad Main wing spar and asked that I get with MotionRC. Well there is nothing you guys can do with this one. I was hoping to show them that they are cutting corners on the Main wing spar of this airframe. I've mocked up a new main wing spar which if I can't find a 4ft. x 3/8 x .2779.044 to .045) alum. tube I will use this one.

Picture below:

[Marco Polo]

Re: FMS P-51b Main Wing Spar

Hi John,
I'm not claiming to be an expert in wing spars, but here are my two cents. It looks like the stock spars covers up to the heavy part of the wing which is where the retracts are. They then leave the rest of the wing without s spar. I'm wondering if this is actually ok, because I know that some flex is necessary in a wing structure, and if you had a really long spare it may decrease the the necessary flexibility of the wing. Do you think that is the reason they didn't make the spar longer?

Mark

[JFandL]

Re: FMS P-51b Main Wing Spar

Mark, I think they make two wing spar's for the price of one. This little 3/8 tube is not going to stop total wing flex. Why would they run a wing tube spar in the wing that long? So you know the makers of the aluminum pipe cut in stock lengths around the world. price is extra if not stock lengths. I know I did some checking. I'm good with how it is, all the guys that are flying this airframe say its good and they are happy. I already made the new spar for mine and its installed. I can't wait she sure is a looker.

Thanks Mark,
I still think the main wing spar should be longer IMHO.

John

BTW FMS said they make it short so that you can get the spar in the wing. 20mm? is more like a 1 foot on each side.

here is what they said" Dear John,


Thank you for your prompt reply. And please measure the spars in your color box. The longer silver one should be 620m. The shorter black one should be 410mm. And the spars should be at least 20mm shorter than the wing tube so that you could always insert the spar even if there is some foam crumbs...Kindly check the length of your spars and keep us updated. Thank you.


Best regards,
Melody "

[JFandL]

Re: FMS P-51b Main Wing Spar

Wow Mark,

FMS emailed me again, this is a very good thing. I just sent the pictures to them and let them see what I'm talking about they can do whatever with them.

"Dear John,


OK, But please also measure the length yourself. Because we cannot get the length from pictures. Thank you.


Best regards,
Melody"

[JFandL]

Re: FMS P-51b Main Wing Spar

Well,

I got 6 flights in two days of flying her. The last two flight I did Lomcevak's at around 15 feet. no wing flex and she flew right out of them again. I do think this main spar needs to be longer. Time will tell I guess. Ver#1 FMS P-51D had a short main spar and wings started to crack right after this spar ended.

For sure FMS needs to make better servo's. Very happy with the way the airframe handle my type of flying.

John