schinus

My Feedback: (2)

My first step into IMAC and I need input on engines for the 77" EXTRA 330. I don't want to do 3D stuff but I want good IMAC performing plane as I start to learn. Have been advised to go for 3.5:1 power to weight ratio. Is there any advantage to gas over glow in this field?? I'm leaning towards BGX-1 3500 @ 4.1 Hp. I have NO experience in gas engines. The EXTRA is advertised to weigh around 14 lbs. Any input here? Thanks in advance.

Tom

brn2fly

My Feedback: (190)

Stay away from the BGX, I have not seen one run right yet. They are junk! Usa a Moki/Marks or a OS 160. You don't need that high of a thrust to weight ratio for IMAC flying only. I woulg go gas but I don't know what you want to spend on an engine. Goodluck with IMAC its a blast!

UDET

HELLO,

As far gas and glow goes the advantage is a gas engine is much cheaper to operate and in my mind this is a big factor because you want to practice A LOT. A gas engine is very easy to operate and will last forever. Their are a bunch of gas motors that have come out or are coming out that would be a real good choice for that aircraft try bcma engines or a brison 2.4 a BME 44 or theirs others out there. Their are lots of good Glow motors out their but they cost more to operate and you need to carry more field equipment.
You will need a high trust to weight ratio when you get into the higher classes in IMAC. If you are going to start out in sportsman or Intermediate class you will not need a rocket.
If you are just starting the most important thing is a good aircraft and a dependable engine and a lot of practice.
Best of luck in IMAC its a HOOT.
UDET

BobbyRichardson

A 120 up would be a good selection for IMAC. I had a Saito 180 on mine and it was overpowered. By the way this is a great IMAC plane

Bobby

DMichael

My Feedback: (5)

Agree with most of what has been posted. Generally speaking, I wouldn't consider a gas engine on an aerobatic plane until you get into say 84" span. The wing loading just gets too high and it's not as competitive or fun to fly. OS 160 sounds good for what you want. 120 might be a little light. A strong 4 stroke - saito 150/180 or a YS 140+ would work too.

One thing that did catch my eye in your post- "Have been advised to go for 3.5:1 power to weight ratio" . You might want to get another opinion.... I have been to many IMAC contests and I have never seen that kind of power to weight ratio in any class. It's unrealistic to attempt - this plane will probably be at least 12-13lbs. At 3.5:1 you'd need about 42lbs of thrust! Anything nearing a 2:1 ratio is plenty for what you're going to be doing.

Dave

zx32tt

My Feedback: (9)

I would not hesitate to put a 45-50 cc size engine on your plane. I have a Poulan 46cc on 78" Texas Hurricane, and it is more than adequate for 3d or anything else. The main issue is the motor box construction strong enough to handle the extra weight. I would go for a good 50 engine, as you can better use on your next plane. Always plan ahead grasshopper.
Z

UDET

Hello,
Normally I would have agreed with DMichael. But their are quite a few good gas engines that are light and powerful. It used to be just as DMichael said the smaller gas engines at the time were heavy and didn't put out the power but they have improved a lot. A OS 160 FX WEIGHS 32.6 OZ without a muffler. a BCMA 4O WEIGHS 51 OZ with the muffler and ignition. The glow engine will need a bigger fuel tank. Glow fuel 10.99 to 18.99 a gallon. Gas well go to the pumps. It sucks to fill up my Ford F-250 Power stroke. But I love it for my DA-100. You might look at the BCMA engines the cost for the 40 was I think 290.00 with the muffler and ignition. I have nothing against glow. I like to practice and I fly a lot so because of that glow is too expensive. One other factor I like is gas has a lot LESS MESS to clean at the end of the day.
Have fun UDET[>:]

dhammond

My Feedback: (2)

I have a GP Extra 300 Gene Soucy that has a 73" wing thats powered by a ZDZ40 and weighs in at 14lbs , Very Reliable and Powerfull ! this a engine that is worth considering if you want to go gas

schinus

My Feedback: (2)

Thanks for all the input and suggestions, guys. I went with the OS 1.60. Don't know if that will do 3D or not but I'm not interested in that.....yet !! It weighs right at 13 lbs. Would be flying it tomorrow if I had been sold the correct spinner adapter for the Tru-Turn 3 1/2" spinner. The APC prop doesn't want to fit in it either because of the bulkiness right around the hub. You guys don't grind out the spinner for prop clearance , do you?? Suggestions here would be appreciated.
Thanks, Tom

randy10926

My Feedback: (19)

So how does it fly?

schinus

My Feedback: (2)

Funny you should ask. It's maiden flight was a bit hair raising. I didn't use any expo and only used high rates. What a mistake. The elevator was so sensitive that it was constantly ballooning. Just getting it on the ground in one piece was a real challenge. Fortunately our club pres. was there and he introduced me to low rates and expo by showing me how to set up my 9 CAP radio. Happy to report all is well and I am learning how to fly it !!!
Thanks, Tom

NJRCFLYER2

My Feedback: (42)

I had a CG Extra some time back. It started out with an ST .74 (don't laugh - it wasn't too bad!). Eventually upgraded to an OS 1.08. Have seen/flown one with a YS 91. You could do up to a 1.20 AX, but frankly, it's not necessary. I suggest that you go for something well behaved and that you ether know about or have some decent local support for. As Dave M. said, this model is not large enough to hit the sweet spot for gas. Don't go there. Frankly, you are probably better off with a reliable 2C with reasonable grunt. Your goal was to practice a bunch. You don't want to get skunked at the field, so something like an OS 1.08 is a good pick because it will generally go when you flip it and won't act up much in the air. There are other good choices, that's just one that I know more about.

NJRCFLYER2

My Feedback: (42)

Oh yeah, the OS 1.60 is a nice engine, but I think it's a bit overmatched against the CG Extra. Besides that fact that it will not fit in the nose too easily, its a bit on the heavy side too and again, not really necessary from a power standpoint. The CG Extra builds out very light, so stick with that theme.

DMichael

My Feedback: (5)

Hey there Ed-

I think he is referring to the "new" Goldberg Extra. It has a 77" wing as opposed to the older Golderberg Extra that you had that has, I think, a 68" span. Even so, I still think it's on the small size for gas. I am anxious to see this new FAI 40 that ZDZ is coming out - that may work for the 77" span Extra. I remember when I first started flying I was able to fly one of the "older" Goldberg Extras- wow, I was impressed! It was fun to fly. It would be fun to do one and put a YS110 or a Saito 125 in it though the best ones I have seen were really light and had YS91s.

I am, of course, happy when I see flyers say they love the way their 77-80" planes fly with gas engines. I wonder, however, how much more they would enjoy that same plane if the wing loading were lowered. You can't beat a well powered lightly loaded plane for aerobatics.

Dave

NJRCFLYER2

My Feedback: (42)

Ooooh-K. Now we're on the same page. Well, in that case, at least an OS 1.60

I don't know where the weight would come out on that model, or for that matter, the CG. If it's anything like it's cousin the CG Yak, it would actually need a big chunk of metal in the nose anyway. I had one (did a review) and with a 2.4 Brison and everything as far forward as possible, it just hit the CG. With an APC prop (read - a HEAVY prop). I will sit back and see how this one turns out, but I suspect that the ZDZ engine you mention actually could be one of the better choices.

schinus

My Feedback: (2)

Had to add about 5 oz. of lead to get the C.G. in the center of what goldberg recommends. Total weight is around 13 1/4 lbs. It certainly is fun to fly but I struggle with the landing. I am having a tendency to come in a little too hot and when I set it down it wants to bounce and become airborn again. I'll get there, just takes time.
BTW....no problem fitting the 120 in the cowl.
Tom

schinus

My Feedback: (2)

Scratch that 120. It is a 160. I was getting confused with a T 34 I was flying today!!