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Who makes a decent 50cc or 100cc IMAC competitive airframe?

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Old 08-13-2013, 05:00 PM
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Default Who makes a decent 50cc or 100cc IMAC competitive airframe?

Bought an Aeroworks 50cc Extra 260. This thing just flies like a dog. Had to add a lot up up thrust to keep the thing from ballooning when you pulled power back from horizontal flight. It's extremely "Pitchy" unless you make it overly nose heavy, to the point that it wants to nose over on the ground.

Since all the incidences are fixed, you're pretty much stuck with a flying toad. Probably ok for 3D but forget any IMAC stuff.

Does anyone make a really good flying large airframe? Really dissappointed....I thought Aeroworks were one of the better mfrs.
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Old 08-13-2013, 05:20 PM
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Getting ready to throw down some cash on a 50cc Aeroworks Extra 300 to learn IMAC, but after reading all the negative comments..I'm not sure what to do. I hear great things from alot of people though..
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Old 08-13-2013, 05:33 PM
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Quote:
Originally Posted by drube View Post
Getting ready to throw down some cash on a 50cc Aeroworks Extra 300 to learn IMAC, but after reading all the negative comments..I'm not sure what to do. I hear great things from alot of people though..
I normally fly pattern and I wasn't expecting pattern plane performance in any of these large airframes, but this Aeroworks 260 flies so badly that it's hard to imagine that anyone ever critiqued it's flying performance before going into production.

Going to probably sell it and do more homework to find a decent airframe.
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Old 08-13-2013, 06:42 PM
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Not that I am a big fan of Aeroworks airplanes but I think you will find that most ARFs are going to need to be measured out and corrected if you want something strait. I have had to do this to Aeroworks, H9, Extreme Flight, Pilot and Comp ARF airplanes. yes there are no adjusters built into these airplanes but on the wings and stabs you can elongate the holes to get the desired adjustment and then lay in some glass cloth on the side of the hole you want to build up then saturate with thin CA. Takes a little time but results in a better flying airplane. I would have to agree that these days there are better choices then Aeroworks.
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Old 08-13-2013, 07:02 PM
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Originally Posted by speedracerntrixie View Post
Not that I am a big fan of Aeroworks airplanes but I think you will find that most ARFs are going to need to be measured out and corrected if you want something strait. I have had to do this to Aeroworks, H9, Extreme Flight, Pilot and Comp ARF airplanes. yes there are no adjusters built into these airplanes but on the wings and stabs you can elongate the holes to get the desired adjustment and then lay in some glass cloth on the side of the hole you want to build up then saturate with thin CA. Takes a little time but results in a better flying airplane. I would have to agree that these days there are better choices then Aeroworks.
I was trying to come up with a way to use the existing Aeroworks wing pins to make an adjustable incidence mechanism similar to the pattern type. Your method sounds more feasable. By adding all the up thrust to remove the ballooning I think I'm just compensating for another issue. Not sure whether to attack the issue with negative wing incidence or positive stab. Never really heard of using negative wing incidence. It also tucks. to the belly pretty bad in knife edge.

I was under the impression that the more expensive airframes were more "Dialed In"? Do Comp ARF, Pilot, and Extreme Flight have adjustable incidence?
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Old 08-13-2013, 07:51 PM
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I have not seen any scale aerobatic airplane that has adjusters. For your airplane I would set the engine and stab to zero and the wing at +.5 degree. I set up every IMAC type airplane I build this way. A couple things you have mentioned is making me think that you are running a fairly aft CG. Every 260 that I have flown had a bit of tuck in knife. Moving the CG forward some will help and you will have to mix out the rest. The first thing is to get everything set correctly and then work on CG. I have owned 4 Aeroworks airplanes dating back to when they made kits. All of them eventually flew really well once sorted out. My only issue with the current offerings is that they are fragile and heavy as compared to other makes.
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Old 08-13-2013, 08:07 PM
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Quote:
Originally Posted by speedracerntrixie View Post
I have not seen any scale aerobatic airplane that has adjusters. For your airplane I would set the engine and stab to zero and the wing at +.5 degree. I set up every IMAC type airplane I build this way. A couple things you have mentioned is making me think that you are running a fairly aft CG. Every 260 that I have flown had a bit of tuck in knife. Moving the CG forward some will help and you will have to mix out the rest. The first thing is to get everything set correctly and then work on CG. I have owned 4 Aeroworks airplanes dating back to when they made kits. All of them eventually flew really well once sorted out. My only issue with the current offerings is that they are fragile and heavy as compared to other makes.
I got rid of the "Pitchy" handling by movving the CG forward. It feels better now but the CG is so far forward that it's nosing over on the ground if you're not really carefull.

By adding the up thrust I got rid of the "ballooning" and now the downlines are good also. I would think that by adding the +.5 deg. incidence it would add to the ballooning effect? Wouldn't you go with negative incidence?
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Old 08-14-2013, 05:40 AM
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Quote:
Originally Posted by FSFLYER View Post
I got rid of the "Pitchy" handling by movving the CG forward. It feels better now but the CG is so far forward that it's nosing over on the ground if you're not really carefull.

By adding the up thrust I got rid of the "ballooning" and now the downlines are good also. I would think that by adding the +.5 deg. incidence it would add to the ballooning effect? Wouldn't you go with negative incidence?
What Speedracer stated is pretty much on the mark. Trimming the model for aerobatic flight is the key and it isn't magic, it's just work we all do as a matter of course. If you understand terms such as MAC, you may want to investigate how the model performs with CG located at various percent of MAC. A typical start point is 25%MAC and working rearward from there. I would not go more than about 35%MAC tho....too many other compromises, even tho the model willl appear to fly okay.

The nose overs are caused by wrong placement of the landing gear. Moving the gear forward 3" (if it's possible) will cure the nose overs.

To the OP, have you guys looked at the Extreme Flight Extras, Yaks and such? EF sells some really nice, well thought out and built models. These tend to be lightweight for their size and pretty strong. The weakest part may be their landing gear blocks but on the larger models these have aluminum angle reinforcements. They will still break but it takes work.
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Old 08-14-2013, 10:03 AM
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Quote:
Originally Posted by MTK View Post
What Speedracer stated is pretty much on the mark. Trimming the model for aerobatic flight is the key and it isn't magic, it's just work we all do as a matter of course. If you understand terms such as MAC, you may want to investigate how the model performs with CG located at various percent of MAC. A typical start point is 25%MAC and working rearward from there. I would not go more than about 35%MAC tho....too many other compromises, even tho the model willl appear to fly okay.

The nose overs are caused by wrong placement of the landing gear. Moving the gear forward 3" (if it's possible) will cure the nose overs.

To the OP, have you guys looked at the Extreme Flight Extras, Yaks and such? EF sells some really nice, well thought out and built models. These tend to be lightweight for their size and pretty strong. The weakest part may be their landing gear blocks but on the larger models these have aluminum angle reinforcements. They will still break but it takes work.
I've run the CG from one extreme to the other. Anything less than the present nose heavy condition results in extreme pitch sensitivity....probably due to the short coupled design. No matter where the CG was placed, it still tucked to the belly in knife edge. I'm aware that changing the gear would cure the nose overs but before I do that I'm going to cut into it to change the wing incidence.

My guess is that due to their specific scale design constraints, these airframes will always have some shortcomings. One design may be a bit better than another and trimming may help improve these but we need to keep in mind that we're not dealing with a dedicated competitve F3A design. As they say, "it is what it is".
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Old 08-14-2013, 02:32 PM
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FSFLYER, in response to your original question, " does anyone make a really good flying large airframe?", check out some of the Composite ARF models. There are hundreds flying IMAC that use them with excellent results. I own several myself & think you will be very pleased....Gene

PS, Look up Andy Kane, hes a Comp ARF rep & lives in the MD area i believe. I'm pretty sure if you hooked up with him you'd get to fly some of his stuff & make up your own mind

Last edited by gene6029; 08-14-2013 at 02:36 PM.
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