RE: ASM B-17G Flying Fortress ARF (120
 

Thanks, I was just wondering if it was just me. I must have missed the part about reinforceing it. I'll do it now.

RE: ASM B-17G Flying Fortress ARF (120
 

Yeah. This was one of many areas that needed work. I renforced it with a doubler of solid hard wood 1/4in. It looked flimsy.

RE: ASM B-17G Flying Fortress ARF (120
 

Can anyone, please tell whats the CoG of that plane;
Is 205 mm back from the leading edge at the point where wing meets fuselage a normal measurement or not;...i think its too back!
i had my maiden flight with that CoG and it was a bit .........scaring!!

RE: ASM B-17G Flying Fortress ARF (120
 

If it's a "bit scaring" you should move the CG further back, not forward. I have this plane with four Magnum 52 four strokes, and had to add 4 pounds of lead, as well as the battery in the nose. It weighs about 30 pounds and flys well. I think the GC in the manual is correct. My CG is near the center of the 205 to 215mm position.

RE: ASM B-17G Flying Fortress ARF (120
 

i will tell you the facts and then tell me what to do.
a. my initial CoG setting was at 195mm back from the leading edge (1 cm further forward than the manual indicates).
b. as soon as i maidened it, it started to climb ALL VERTICAL like a rocket towards the moon!!! (my initial elevator trim setting was at absolute zero-level)
c. plane started to fly level as soon as i trimmed my elevator DOWN at about 1cm!!!! from zero point.
d. my landing was a bit scaring since i had not much up elevator travel to handle it durind approach (by the time i cut throttles my plane went down really hard) so i had to come really hot in order not to loose height so rapidly.
e. after that it seems that my plane is tail heavy

Is that normal that manual indicates such a CoG(205mm) while total wing width(chord) at the point where it meets the fuselage is only 55cm; its not even the 1/3 of the total chord: (1/3)*55=18,3 cm!!so it means that 20,5 cm is further back about 2,2 cm from 18,3 cm...!PLEASE TELL ME WHERE I AM WRONG...

its really strange that you guys doesnt seem to have such a problems with CoG seeting at 205mm!!

RE: ASM B-17G Flying Fortress ARF (120
 

The problem is your motor incidence setup. I had the same thing happen. My plane is balanced perfectly. However, I noticed the engine nacelles may have not been square. The dowel and mounting system of the nacelles leaves much to be desired. They can be off 3-4 degrees depending on the initial building at the factory. So I reinforced the mounting blocks and left what I saw alone until the first flight. I was right!! I knew then that I had to change the wing or motor incidence. Since changing the wing incidence was impossible the easy thing is to change the motor incidences. Make sure the plane is balanced first and add down thrust to the motors. You will have a great flying plane!!!:)

RE: ASM B-17G Flying Fortress ARF (120
 

Thank you for your reply you have been very helpful! i will recheck my motor thrust and i will add some down thrust if necessary, but what i cannot understand is how is it possible for a plane like that (warbird... its still a warbird although its a bomber) to balance so further back than 1/3 of the total wing root chord since i have never had any other warbird with such a "tailheavy" CoG!... I am curious if lancaster plane of the same manufacturer (ASM) balances the same way. I am saying that because all ESM-YT-KONDOR warbirds models balance further forward that 1/3 of the total wing root chord....does it have to do with wing incidence....;

RE: ASM B-17G Flying Fortress ARF (120
 

Mine went straight up also. See my maiden video. Down trim and it was fine. CG was perfect out of the manual.

SR

RE: ASM B-17G Flying Fortress ARF (120
 

Mine is balanced at 200mm. The wing has a lot of UP incidence in it, just like the real one. However, you cannot compare the real one with this model. There was a lot of washout on the real one and I am sure the radials had a different incidence setting than the root of the wings otherwise they would be pointing up!! Anyway, after adjusting the motors with down thrust it was fine. I have not noticed any bad tendencies to make me think the plane is not balanced correctly. You really cannot adjust anything else. You cannot change the wing incidence unless you reseat the wing and you cannot change the stab incidence easily either. The motors are the only thing left. Mine was easy to do because it was electric. I added 2 washers.

RE: ASM B-17G Flying Fortress ARF (120
 

[size=2]A friend and I are assembling one now. I see some people are using 4.5 inch mains. I contacted global a bit ago and the said 5.00 inch mains. Anyone use 5 inchers?

Thanks in adv.

john

RE: ASM B-17G Flying Fortress ARF (120
 

I used the 4 1/2 inch wheels that are supplied with the retracts, but I think that 5 inch would work ok. You may have to trim the front of the<span class="Apple-style-span" style="font-family: Helvetica; ">nacelle a bit for it to fit, but it looks like there is plenty of room for the extra 1/4 inch.
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RE: ASM B-17G Flying Fortress ARF (120
 

I have just measured motors down thrust with Robart incidence meter and i have found 6 deg down thrust!!(the central wing airfoil was put at 0 deg refernce point at that measurement). i havent measured wing incidence yet but i agree with you that it probably has positive incidence, say 2 or 3 degres; because its a bomber whose task was to cary heavy bombs at relatively low speeds so extra lift from positive wing incidence was necessary, so total motor down thrust must be : 6 degres - 3 degres = 3 degres. Probably due to the fact that wing has semisymetric airfoil and plane has also many motors combining their thrust , its possible that extra down thrust might be necessary.

RE: ASM B-17G Flying Fortress ARF (120
 

Hi Randy,

Probably too late but i've just bought what is probably the last asm B17 to be sold in the UK and I'll need retracts. Can you help? Still got yours for sale?

Cheers,

Stew.<br type="_moz" />

RE: ASM B-17G Flying Fortress ARF (120
 

Last weekend i had second and third flight of my B-17 and i can say that manual CoG setting isnt for me. it was the first time i decided to follow manual CoG ( i always balance my planes at 1/4 of the total wing root chord) but during second flight b-17 was tailheavy and while final turning for landing i had a very dangerous tip stall that i managed to recover from just before i hit the ground. i must admit that i made a turn at a rather high angle of attack but i still cant give any reasons for that sudden tip stall ecxept for tailheavy behavior. At third flight a added some balast and plane behaved excellently!! Now my CoG is at 17 cm and not at 20 cm as manual indicates. I didnt add any more down thrust because after putting some balast my plane didnt need any.

RE: ASM B-17G Flying Fortress ARF (120
 

I guess I'm a little confused about you CG: The manual I got here in the US says the CG should be between 205mm and 215mm back from the leading edge. If you move it FORWARD to 170mm it would be more tail heavy, not less.
Mine is about in the center or the<span class="Apple-style-span" style="font-family: Arial; ">recommended</span>range and I have not noticed any CG problems.<br type="_moz" />

RE: ASM B-17G Flying Fortress ARF (120
 

by saying "moving forward to 170 mm" i mean that i added some balast-weight in the nose and after that my new CoG moved to 170mm from leading edge so my plane became more noseheavy than yours.

RE: ASM B-17G Flying Fortress ARF (120
 

dgiatr:
I have 4 Magnum XL52s on mine. I had to add 4 pounds of lead in the nose as well as the flight battery to get the CG to the recommended range. How much weight did you have to add? My all up weight is about 30 to 32 pounds, and it still flys great.
<br type="_moz" />

RE: ASM B-17G Flying Fortress ARF (120
 

You know guys. I've seen and I'm in the P40 brotherhood, so has the idea of starting a B17 brotherhood came up, is anyone interested in something like that?

RE: ASM B-17G Flying Fortress ARF (120
 

i have done mine electric, so i have two batteries , one battery for the two outer motors and one battery for the two inner motors. batteries are 6s 6000 mah and i think its about 900 gr each one, so i have 2x900 = 1,8 kgr in the front part of my fuselage only from those batteries, i have also added 1,3 kg lead weight at the front of my batteries towards the nose of the fuselage, so total weight at the front part of my fuselage must be : 1,8+1,3=3,1 kgr. Plane total weight is 15,5 kgr and at that CoG setting plane flies really fine. My only problem now is that plane is prone to nose over sometimes so next time i will substract only 0,3 kgr from lead weight and i will also put my tail wheel (i dont have retractable wheel) closer to the fuselage so my plane could sit in a greater anlge from the ground.

RE: ASM B-17G Flying Fortress ARF (120
 

My first flight with 4S LiPO setup


[youtube]http://www.youtube.com/watch?v=ad1Deo8DfXQ&list=UU4iv-9RkxjBiy1C5waVtuFg&index=2&feature=plcp[/youtube]

RE: ASM B-17G Flying Fortress ARF (120
 

Totally love it my friend. Great job.

SR

RE: ASM B-17G Flying Fortress ARF (120
 

Hi
Ive just bought a ASM -17:) it stand with Electric motors, and Thats is not okay.. Have seen your youtube video, awesome:) so i am gonna buy 4 saito 62's.. How did you build the straight pipes, and still get pressure for the fuel tanks????
Regards Dan

RE: ASM B-17G Flying Fortress ARF (120
 

Ive bought it from Affa:)

RE: ASM B-17G Flying Fortress ARF (120
 

The pipes are 90 degree fittings with the straight muffler extensions cut off then a fuel adapter screwed into the 90. The lines have to be as short a possible!

SR.

RE: ASM B-17G Flying Fortress ARF (120
 

Thank youhttp://www.rcuniverse.com/forum/js/f...ular_smile.gifSound really good..
But before i Can get the plane, i have a 4 Month Tour in wonderfull Afghanistan!!! Looking forward to getting the plane and rebuild it, with the saito'shttp://www.rcuniverse.com/forum/js/f...wink_smile.gif
Regards Dan

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