IMAC-legal 50cc-sized planes??

[eajohnson]

Hi, I've been looking for a 50cc-sized airframe to convert to electric and fly in sportsman next year. I have been frustrated to find that some of the best flying planes (e.g. 3DH 89" Slick ) couldn't possibly meet the rule 6 scale requirements, as the fuselages exceed the scale length by more than 10%.

Can anyone recommend a 50cc sized airframe that _is_ IMAC-legal? Or do people just fly aircraft that bend the rules? I'm not a rule-bending kind of guy so I'm not really comfortable with that.

NOTE: original post questioned the Extreme Flight 88" Extra as well, however it is a) a 300 not a 300L and thus the scale fuse is the longer of the two and b) measurements of an actual example (see thread) showed 85" fuselage lenght inclusive of spinner which is within the permitted scale range, whereas the published 87" on the extreme flight web site is just a tad long. So it appears that an extreme flight 88 Extra is a very nice candidate.

[bodywerks]

Well, the EF Extra is not an L it is a straight midwing plain ol' 300.
EXTRA 300 http://bjaffee.rchomepage.com/extrapage/

Engine AEIO-540 L1B5 Horsepower 300 @ 2700rpm Propeller 3 bladed constant speed Max ramp weight 2095 lbs Gross weight 2095 lbs Empty weight 1470 lbs Usefull load 625 lbs Payload (full fuel) 371 lbs Fuel Capacity 42.3 US gal Wingspan 26.25 ft Overall length 23.36 ft Height 8.6 ft Wing area 115.2 sq ft Wheel track 11.47 ft Seating capacity 2

at an 88.5" span, the EF 300 is 28.1% to scale. 28.1% of 23.36 feet is 78.76". Forget about ratios, it is measurements that can be 10% deviated. An additional 10% allows for an 86.6" fuse length, therebouts. The EF advertises at 87" and may include the spinner and we don't know if the scale drawing includes the spinner. Basically, 87" is close enough.
The "10% rule" is so vague that it can be interpreted in many ways. So long as the plane you fly looks like a representation of a full scale design, you will be hard-pressed to find anyone that will challenge you and not let you fly, especially at local contests in the sportsman class. They didn't come and measure my plane at the Tucson Shootout and I didn't see them do it to anyone else there, and I am pretty sure nobody at the AMA nats had to prove the scaleness of their plane.
Don't sweat the petty stuff (and don't pet the sweaty stuff either, lol!).

[STLAV8R]

Don't sweat the petty stuff (and don't pet the sweaty stuff either, lol!).[/quote]

[eajohnson]

I figured with the canopy like it was it had to be an L, otherwise the canopy doesn't look right so it wouldn't look like the correct airplane at 10' away (or whatever the distance is supposed to be). I guess the wing position wouldn't be right for an L. Anyway, assuming it's not an L, the length of the 330 is 23.36 inclusive of the spinner and span is 26.25, so the max length would still be (for 88.25), that would give a max length of 86.38 as you say which is _almost_ legal but only if the Extreme Flight measurement includes the spinner. (see page 6 http://www.extraaircraft.com/Tech-Ma...MM300/CH06.pdf)

[eajohnson]

	Quote:
	Don't sweat the petty stuff (and don't pet the sweaty stuff either, lol!).

I just want to be sure I'm in strict conformance to the rules, don't want to drop $3k+ on a plane (which is what it'll cost as an electric) only to find out that it's not within spec. Others might be happy with that but I couldn't live with myself if I knew I was cheating even in a small way.

[propchief]

That specific plane has a few IMAC wins under it's wings (so to speak.) ... and has competed in lots of contests. I think it's pretty safe to say you would be fine with that plane.

[eajohnson]

	Quote: Originally Posted by propchief
	That specific plane has a few IMAC wins under it's wings (so to speak.) ... and has competed in lots of contests. I think it's pretty safe to say you would be fine with that plane.

I guess there would be some argument to be made there to convince a CD. These were presumably not Basic wins right? If the EF 88" Extra's 87" does include the spinner it definitely is close; if it doesn't then it's not really all that close since the spinner would account for ~6% or roughly 5" of the total length of the model (based on measurements of the spinner on the fuselage in the service manual drawings). Guess that's the critical factor here. Anyone got one they can measure?

[STLAV8R]

	Quote: Originally Posted by eajohnson
	I guess there would be some argument to be made there to convince a CD. These were presumably not Basic wins right? If the EF 88" Extra's 87" does include the spinner it definitely is close; if it doesn't then it's not really all that close since the spinner would account for ~6% or roughly 5" of the total length of the model (based on measurements of the spinner on the fuselage in the service manual drawings). Guess that's the critical factor here. Anyone got one they can measure?

Just measured mine for you: 85" from the tip of the spinner to the TE of the rudder at the bottom. Hope this helps.

[sweetpea]

Also TAS is not IMAC. It uses most IMAC rules and uses IMAC as the part of the basis to be accepted.

The AMA NATS though is a good choice of example. As long as the plane looks like an Extra it will be ok.

There are planes out there like the Carden Yak and the Columbo Anderson Extra for example that streeeeeetch the rule to its max.

[eajohnson]

	Quote: Originally Posted by STLAV8R
	Just measured mine for you: 85" from the tip of the spinner to the TE of the rudder at the bottom. Hope this helps.

That is a HUGE help, and really good news for me. :-) !! Will update 1st post.

[sukhoi26mx]

If the Quique "Yextra" (Yak) is allowed, I figure that if it looks sort of like an aerobatic airplane they'd be hard pressed to inforce that rule.

Scott

[jamesrxx951]

i've often wondered about the QQ 101 yak. that nose is just absolutley long compared to other yaks,even the 102 side by side. and it seems to be legal. just wondered if imac really does enforce the 10%rule just because it would mean that they would have to have spec's for all planes that could enter and measure them. just my thoughts.

[3D-Seth]

I have never, ever, had anyone, or seen anyone question my airplanes, or anyone elses airplanes in the 4 years I have been flying IMAC, including at the past 3 AMA IMAC NATS, and Clover Creek events.

I wouldn't sweat it as long as it looks like a full scale. Now, if you go out and fly a pattern plane, obviously they will say something, but as long as its modeled after a full scale, no one is going to say anything to you.

Seth

[Aerobat]

I fly IMAC in Sportsman class, and I CD a local IMAC contest...and I also own a Columbo "Extra 330" which was recently flown to a 3rd place finish in Intermediate by my buddy. I have never known of a CD even considering the 10% rule. As the posters say above, as long as it's modeled after a full scale aerobatic plane, you'll be fine.