ChuckC

My Feedback: (24)

Yes, I know it's been mentioned before and after searching here it seems that about 1/4 inch ahead of recommended CG in book is the way to go, but...

I've got the old YA A-4 with scale wings. It was supposed to not have saddle tanks, but I squeezed them in, with modifications.

The old instruction book (the kit I've got) says 11 and 5/8 inches from trailing edge and the new one states 12 inches. If I go 12 and 1/4 inches, will I have any issues with the plane? I don't mind sedate and I want to avoid the "snap of death".

Thanks,

Chuck

Shaun Evans

Chuck,

Go ahead and go with the 12.5" line. If the plane is a wee bit nose heavy, it will still fly fine, and with less tendancy to approach a stall. This plane is very tolerant of a forward CG, just not of an aft one. Good luck!

ChuckC

My Feedback: (24)

Thanks Sean-That's what I needed to know.

Now for some more lead...

rc.hackmaster

My Feedback: (4)

can you post a pic of your tanks that you squeezed in? i also have a older a4 and want to use saddle tanks. thanks, hack.

Johng

My Feedback: (4)

Yeah, more info on the saddle tank mod....

SECRET AGENT

My Feedback: (18)

Nuthin for nuthin, and maybe shaun can help me out with this, but, mine was balance right on 12" and wouldn't rotate. (because it wouldn't rotate, it is now noseless) Once I fix the nose I will change the CG to 11.5. It sits with about a 9 degree positive angle of attack so by all accounts it shoulda rotated all by itself. Everyone who felt it said it felt noseheavy (but I stuck to my guns and kept it at 12" darn-it). I had even canted the gear towards the CG for easy rotation. Man was it fast (until it ran outa runway - hee hee). Next time I will try a ramp so it will be airborne at least momentarily ha ha. Hope your first flight is a winner, I wish you best of luck.

Mike

ChuckC

My Feedback: (24)

I'll get some pic's of my installation-it's not real "pretty" and the hatch doesn't fit perfect (close enough, though). Al I had to really do was cut some of the flange off the engine cover cap to get them crammed in there and carefully route the fuel lines.

12" didn't get it to rotate? Was that scale or sport wing? I've got a very long runway, so I may try anyways and will let you know what it takes to get mine off the concrete.

SECRET AGENT

My Feedback: (18)

Mine was the sport wing, coulda had a freeway and it still wouldn't have rotated. I used about 1000 feet before catching the grass ( i was at the end of a full size runway). Good luck!!

Mike

ChuckC

My Feedback: (24)

Thanks, THAT'S encouraging! Guess I'll see...I think I've got about 2-3,000 feet of runway to use. Boy I hope it's not all necessary!

SECRET AGENT

My Feedback: (18)

Chuck,
I really don't want to bum you out because I really love my little A-4. I just need to figure out the CG on my own and not rely on whats in the book. There are lots of ways both mathmatical and mechanical, I plan on using the old hanging it by a string test, it's worked for me in the past. I believe BVM had that way posted on his web-site for a while, or it coulda been JPO (i really can't remember). Anyway, once I get a new nose spliced on her, I'll try again. Hope your first flight is a great success. Just keep 'em moving fast and everything should be ok. Good Luck!

Mike

ChuckC

My Feedback: (24)

To add the standard Sullivan saddle tanks, I carved off some of the mating flange of the engine cover cap and I also modified the cover cap.

The modification was to see where the tanks were hitting the cap, mark it with a sharpie pen and cut the corresponding holes-a little at first, check, then cut some more. After I was satisfied with the holes in the engine cover cap, I shoved a bunch of paper over the engine and put a bunch of Saran wrap over the paper (and anything else that might get epoxy on it). The cover cap was sanded with 80 grit on the inside and out. I took a couple of pieces of 6 oz. cloth, wetted it with epoxy and laid the epoxy/cloth inside the cover cap over the holes I made. I then put the cover cap in position on top of the paper/Saran wrap. Put some more Saran wrap over the cover cap (so nothing sticks)and shove everything (tanks, push rod) in place. Let it kick and voila! Not a perfect fit, but I was in a hurry at the time.

ChuckC

My Feedback: (24)

Note: the wiring and fuel lines were not "molded in" lie the tanks and push-rod. Note also the slight bowing in the fuse. This is what I referred to as the hatch not fitting perfectly, but it can be corrected-I just haven't yet. This install also requires very stubby brass fuel tubes coming out of the tanks-I flared the brass ends with a center punch and then used some very small zip-ties to secure the tubing; worked so good I did this on all my brass tubes.

rc.hackmaster

My Feedback: (4)

very interesting, that was the only place i could find to put them also. havent even started finishing the a4 as of yet, still working on the f16. thanks for the pics. doug