Hi Zoot Fox enough for a Humongous?

Hi All,

Would a Randy Smith Fox 35 with all the goodies (ABC, HZ, hemi, stuffer, etc) be powerful enough to haul a 36 oz Humongous? The weight is obviously no problem, but the wing is well described by the plane's name: ~ 650 sq in, and thick.

Looking through back issues of SN at what others have used, I see everything from 40's up to Fox 59, and even one ST 60! I have a Fox 59, which would need a strap-on muffler (no lugs) and a K&B 40 ABC, which would produce enough power, but is on the heavy side (12 oz w/muffler). I like the combination of modern metals and traditional porting in the Fox and K&B.

Any advice would be appreciated.

Thanks,

Kim Mortimore

LAST EDITED ON Jul-14-04 AT 07:14 PM (CDT)
 
NO WAY! Mine started out with a K&B .40S (#4055, the Brodak Stunt version). The airplane weighed 47 oz with it, RTF less fuel. Static thrust was about equal to weight with an 11-5 Bull_Y&O, and it was dangerously underpowered. The OS .46LA was just about right. As I have an extra ST G.51 (Dirt rework), I'd be tempted to build one around that. It typically needs the noseweight of a .46LA or G.51. The Viking, Zilch X, or Barnstormer is a better match to a Fox .35. These things have to cruise along at 65-70 mph, the wing is thick, so it does take some engine to do it. Steve

Thanks, Steve. Where should it balance for best results?

LAST EDITED ON Jul-14-04 AT 07:41 PM (CDT)
 
I have no useful info on that, but with the K&B, it needed tail weight with a Brodak tongue muffler. With the OS .46LA and Mac's Muffler, it needed noseweight. It's my view that you need to adjust it to suit you, not me. Also, unless you have a CG Machine (string cradle, plumb-bob, etc), anything you do to check the CG is not accurate enough to be very meaningful. IMO. Steve

LAST EDITED ON Jul-14-04 AT 07:49 PM (CDT)
 
an LA 40 will easily fly a 750 sq. in. 18% wing plane weighing 49 oz. I'd give the Fox a try. 36 oz. is just about right for that size wing. I wouldn't be surprised at all if a 45 ouncer was having trouble. Try the balance at around 17% back from the leading edge for starters.

You might use the clamp type mounts so you could easily change motors if the Fox turns out to be too wimpy.

>You might use the clamp type mounts so you could easily
>change motors if the Fox turns out to be too wimpy.

Funny you should mention that, Phil! The Humo does in fact have Windy clamp mounts, redrilled for smaller than 60 engines. When I first heard about clamp mounts, I thought they sounded suspect from a strength/reliability standpoint, but if Experts are using them for piped 65's, I guess they're plenty good enough for me.

Steve's plane is/was 30% heavier than mine, which is quite a bit.

Kim, It just so happens, I have one of those Brodak K&B .40 ABC motors as mentioned above. Give me a call Friday night, remind me to bring it out. It should work find on that plane.

>Kim, It just so happens, I have one of those Brodak K&B .40
>ABC motors as mentioned above. Give me a call Friday night,
>remind me to bring it out. It should work find on that
>plane.
>
>Larry, NorCal Circle Jerks.

Thanks, Larry. That will save me having to break in my NIB K&B to see if it works. Jim and I test fit the K&B and all it needs is a little grinding on the inboard top clamp, which I will do between now and Saturday so we can just clamp 'n fly. Got hardware for OT and PA both now. From rags to riches in a hurry!

Kim

Hi there I have two Humongi ??? One is 33 oz rtf and one is 36 oz rtf NOt kit built. In my opinion the plane simply is over designed. For example my plans call for fuse bottom of 1/4 balsa.and 1/16 works well The lighter (uglier ) one flies well with a FP 40 and the heavier one flies great great with a LA 46. 11.5 x4 or 11x4 APC on .018 cables 62 feet to centre of fuse. lap times around 5 sec feel best to me even if windy. the balance point seems to need to be 10" ahead of the trailing edge to give easy level flight when inverted. Dont forget this is a completely in line design ,engine wing and stab,Prone to wander unless balanced well foreward. I hate to have to carry any useless weight and I think the use of a four stroke engine would be great soundwise and balance wise. However my plans show a fox 35 in the original. I wonder how heavy the original one was. remember they used very little dope then.compared to the current trend.Any way good luck, I love mine and I am always glad to let other people fly mine cause im proud of how pleasantly they fly.Chris Cox flew mine and said that if I dont win with that plane I should have my ##### kicked,It flies so nice. They do nice tight corners also so it can score well in PA or Classic. Keith Varley

I agree with Steve. My Humongous came in at 43 oz. One thing that happens to a big plane that is built light is when the wind picks up it get bounced all over the place. Plus the ribs on this plane are 2" thick, the drag they produce really hold it back. The only way to fix this is to add more power. Emil Kovak has a Double Star 60 lite in his and claims it is one of the best OT planes he has ever flown. I had a Dixon FP 40 in mine and it flew great until the wind got over 5 mph. The LA 46 should be OK but the only prop I have found to work on a stock engine is the APC 11.5x4. No room to experiment. The next engine I am going to try next is an Enya 45, 6001. I also had to add about 2 oz of lead to make it balance with the FP. This is a fun plane and there is room for all kinds of experimenting while building and choice of engines. Don't use balsa that is too light for the leading edge or you will get dips in between the ribs. This plane is also a good candidate for polyspan, with silkspan on the wing tips. A 50 oz plane should fly real well if the power is matched up right. I would bet an old ST 46 would be a great combo. Go for it. The modifications to the LA 46 and 40 are real easy, done by notching the piston where the bypass ports open. About 1mm deep and about 1/4 to 1/3 to the center of the piston with a jewelers file. The width can be a touch wider than the liner openings. This will calm the engine down a bit and make it more friendly for other props. Jim J

Mine was silk with tissue on the tail. I blush to say it came out at 52 oz. I had to add considerable nose weight with a K&B 4011. However it was (now retired due to cracking of unplasticized Aerogloss)one of my favorite airplanes and I never thought it underpowered. Mine was scratch buit from Ted Snow's 1/4 scale drawing. It is pictured in the RSM ad. I sheeted the leading edge with very light balsa and it did develop dips between the ribs. I D-tubed the wing and put 1/16 sheet top and bottom on the fuselage with stringers over.

RSM says it's 630 sq. in., and it's a thick wing, like I said, and a draggy fuselage, which I didn't. Nobody would like it with any Fox .35 Stunt.

The lightest Humongus I've seen was Emil Kovac's, at the NW CL Regionals. He covered it with clear film of some sort (as light as it gets), and it had no cockpit or headrest. It weighed 36 oz, with a Tom Muggleston (sp?) "Happy Camper" .40FP, and flew very well. Emil built a series of light Ringmasters (as little as 16 oz. with .15FP's), and built my Humongus...from scratch. I think he rejected it, because it was too heavy. Flew ok for an OTS, with enough power. Steve

>
>Hi All,
>
>Would a Randy Smith Fox 35 with all the goodies (ABC, HZ,
>hemi, stuffer, etc) be powerful enough to haul a 36 oz
>Humongous? The weight is obviously no problem, but the wing
>is well described by the plane's name: ~ 650 sq in, and
>thick.
>
>Looking through back issues of SN at what others have used,
>I see everything from 40's up to Fox 59, and even one ST 60!
> I have a Fox 59, which would need a strap-on muffler (no
>lugs) and a K&B 40 ABC, which would produce enough power,
>but is on the heavy side (12 oz w/muffler). I like the
>combination of modern metals and traditional porting in the
>Fox and K&B.
>
>Any advice would be appreciated.
>
>Thanks,
>
>Kim Mortimore
>
>A Jerk on Saturday and
>A Nut on Sunday

Ron B.
F4Fguy

Mine flies just fine on a Triumph 49 at 42oz. The Randy Smith Fox probably has as much power,but will have to be propped differently to put it in the right torque range.I'm running a 12-5 on the Triumph.

I've been very pleased with the Humongous,it goes where you point it and can be flown at almost any speed.My only big adjustment problem was finding a prop and RPM that would slow it down enough.As was said elswhere, they seem to prefer a relatively forward balance point.This could be a problem with the Fox.As to the "dragginess",I haven't noticed it,at least compared to other OTs.When the engine quits, the glide is very good,allowing long smooth approaches and good three point stall landings.