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Racing Mongoose

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Racing Mongoose

Post  JPvelo on Fri Oct 24, 2014 4:10 pm

I'm down to finishing touches on my mongoose I built for club racing. It's a blackhawk kit of a Dick Mathis design.




Engine is an ASP .25 Rc engine with a venturi turned by my friend Ed, O.S. needle valve.
The tank setup is far from aerodynamic but I don't need to worry about aerodynamics until I get the pit stop process down.


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Re: Racing Mongoose

Post  rsv1cox on Fri Oct 24, 2014 4:32 pm

So nice!!!! Love your covering, what did you use? Great lead-outs too. How is that single wheel going to work for you? Not much drag there.
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Re: Racing Mongoose

Post  Cribbs74 on Fri Oct 24, 2014 5:41 pm

Cool Jim,

That engine is way out there. Do they build really tail heavy?

Ron
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Re: Racing Mongoose

Post  Ken Cook on Fri Oct 24, 2014 6:29 pm

Jim, is that being used for slow rat ?
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Re: Racing Mongoose

Post  Cribbs74 on Fri Oct 24, 2014 6:37 pm

I think he said Foxberg in another post.

I guess they are more liberal in Arizona! lol!

Jim it looks great BTW, forgot to mention that!

Ron
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Re: Racing Mongoose

Post  RknRusty on Fri Oct 24, 2014 9:23 pm

That is really classy looking. Very neat and well thought out. Jim when you're old and gray, your name is probably going to fall in the same sentence as "The Big Guys." You're moving from dabbling to serious at an impressive pace. That's a good looking vent setup too. I hope it all works as well. I bet that ball bearing 25 really honks ass. I know my Thunder Tiger 25 does. If I ever get a speed limit Combat plane, that'll be my first engine to use.
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Re: Racing Mongoose

Post  RknRusty on Fri Oct 24, 2014 9:26 pm

Do racers use wood props? That seems too easy to break at a bad time.

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Re: Racing Mongoose

Post  Cribbs74 on Fri Oct 24, 2014 11:14 pm

I assume they do Rusty, Ken sent me this Dooling along with a few speed props to go with it. The one mounted is one I have never seen before. It's a TF 7x7 1/2 .55

It's a neat prop, but looks very fragile.



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Re: Racing Mongoose

Post  Mark Boesen on Fri Oct 24, 2014 11:45 pm

RknRusty wrote:Do racers use wood props? That seems too easy to break at a bad time.

I think its a personal thing, wood props are easier to modify and balance, less damage to your hand if struck, look cooler and possibly less engine (crank) damage if crashed, but you can't argue with the popularity of APC props.
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Re: Racing Mongoose

Post  JPvelo on Sat Oct 25, 2014 1:09 am

Rsv,

The red is monocoat the black is ultracote. The single wheel is to reduce drag but I need  to install wingtip skids.

Ken,

It's for Central Arizona Control Line  Clubs' vintage racing. About thirty different plans to choose from. Fox & McCoy .35s or any unmodified .25, no speed or racing special engines. Top Flite 9x6 PowerPoint props supplied by the club and club supplied 10/20 fuel. If foxberg and super slow rat had a love child it would be this. We're talking to the Cholla Choppers down in Tucson about a four race series with races alternating between Phoenix and Tucson. If it takes off I will propose making super slow rat airframes eligible next year. I'd also like to see choice of any widely available prop.

Ron,
I don't know why it was designed with the engine bearers cut short. It's actualy a very short front end. That's a 2 3/4" long 2oz. tank and it's mounted inboard because it won't fit behind the engine. It still came out nose heavy.

Rusty,
Thanks for the compliment, it means a lot coming from you. I'm sure your name will be up there as well. I ran the engine for the first time today, two slobbering rich runs with the muffler so the neighbors don't get p'd off. I won't have a chance to fly it until next Friday.Did  you notice that's a Tee Dee venturi I'm using for a home made fast fill?

Jim
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Re: Racing Mongoose

Post  getback on Sat Oct 25, 2014 7:36 am

Quote : you notice that's a Tee Dee venturi I'm using for a home made fast fill?
I noticed that but , thought it was just for pressure ? Is the red nipple not going to overflow before full or it has a one way valve in it ? Nice Looking Plane Jim . Eric Very Happy
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Re: Racing Mongoose

Post  JPvelo on Sat Oct 25, 2014 8:38 am

getback wrote:Quote :  you notice that's a Tee Dee venturi I'm using for a home made fast fill?
I noticed that but , thought it was just for pressure ? Is the red nipple not going to overflow before full or it has a one way valve in it ? Nice Looking Plane Jim . Eric Very Happy
Here's how it all works. The red nipple is the overflow that's plumbed to the very top front of the tank. The nipple is actually a check valve that only flows OUT of the tank. The Tee Dee venturi is the uniflow vent and is also used for filling. To fill in a race you pinch the line to the engine and fuel with a squeeze bottle with nipple that fits into the venturi. The valve lets it vent without any complicated pinch devices or removing and replacing a cap that can get lost.
This my current squeez bottle but it's not as pliable as I had hoped, I need something soft enough to fill the 2oz. tank with one good firm squeeze.
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Re: Racing Mongoose

Post  getback on Sat Oct 25, 2014 10:46 am

Cool ! Thanks Speedy Jim Very Happy   Eric


Last edited by getback on Sat Oct 25, 2014 11:05 am; edited 1 time in total (Reason for editing : used wrong name)
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Re: Racing Mongoose

Post  JPvelo on Sat Nov 08, 2014 3:43 pm

Finally flew the mongoose the last two days. Yesterday was unsuccessful as centrifugal force caused the inboard mounted tank to flood the engine as soon as it was airborne. Replaced it with a 3oz wedge mounted outboard on a standoff so the feed line clears the motor. Flys great but it takes about ten laps to lean out. I'm launching rich as the motor only has five or six tanks through it so far. I'll start to lean it out next time I fly it. I'm curious to see what it will do as I was getting 70mph and it's rich enough you could practically pick it up by the motor after the flight. I need to switch to a 2oz tank per racing rules. I'm picking up a 2oz tank at the club meeting Tuesday nite. Stay tuned.

Jim
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Re: Racing Mongoose

Post  Cribbs74 on Sat Nov 08, 2014 11:08 pm

I was wondering how that inboard tank would work. I figured it was a speed thing and not in my comfort zone to comment on.

70mph sounds plenty quick for a rich run. Take some vids once you lean that puppy out.

Ron
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Re: Racing Mongoose

Post  Oldenginerod on Sat Nov 08, 2014 11:48 pm

I reckon it'll go a whole lot faster if you run it on nitro rather than that rich mustard lol!
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Re: Racing Mongoose

Post  JPvelo on Sun Nov 09, 2014 6:29 am

Oldenginerod wrote:I reckon it'll go a whole lot faster if you run it on nitro rather than that rich mustard lol!

Once it's broken in I'll switch from  "mild" to  "spicy"!
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Dick Mathis Mongoose by Black Hawk Models

Post  fredvon4 on Sun Nov 09, 2014 8:20 am

One of my favorites of my youth. I bought every kit our 5 and Dime store had one winter and built all 7 of them production style. Quite interesting that Jim used Red and Black as that was my usual color pair for almost all my balsa airplanes.

Great looking model Jim.

I have one of the BH kits but am waiting for my grandson to get a bit older. In a few years I am sure we grandparents will host him for a summer.  I hope he is interested enough to let me coach him in the building of several different kits. My 33 year old son is interested but much too busy earning money, hunting, boating, side by side riding, and chasing skirt to spend the requisite time with dad's hobby.

While I wait to capture young Jackson's imagination with noisy glow fuel aviation, I have copied many of the BH Mongoose kit parts to fit a foam version of the wing.

Jim the short nose is because this is a championship Combat design by Dick Mathis intended to fly fast and turn very tight (by the standards of back then).

If you stick with this plane for the racing series and the rules allow I would suggest the next build have a longer nose for good suction tank location and choice. And making the tail a bit longer using heavier ply for the tail feathers to balance.

That wing will fly fine at a slightly heavier weight and not sink like a rock to land. I flew them with Enya .35s that are much heavier engine than the intended Fox 35. And I tended to build heavy with some fiberglass or critical parts that combat usually broke. What I am saying is that my heavy versions still had 1/2 to 3/4 lap floating power off landings that I could usually coax back to my pit buddy.
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Re: Racing Mongoose

Post  ian1954 on Sun Nov 09, 2014 8:40 am

I like the wings on this - I always find that being able to see through the covering to the ribs and construction adds something. The finish looks superb.

I now have several models approaching "finishing" and hope that I can achieve quality finishes like this (and quite a few models I peruse on this site). I keep procrastinating.

However, I "must" draw attention to the mustard bottle. I tried this while I was in Chicago and found it a little bland for my taste. It just seemed to add colour. I preferred the Luisiana Cajun mustard but I am afraid that neither come up to scratch with Colmans English mustard! Nice and fiery, almost as hot as Chinese mustard.

I would buy it to use the bottle but Colmans mustard tins make excellent tanks!

I like the use of the venturi for fast fill but does it double as an air scoop?
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Re: Racing Mongoose

Post  fredvon4 on Sun Nov 09, 2014 8:55 am

The tank he is using is plumbed for Uniflo so yes there is a ram air effect from the Tee Dee venturi fast fill receptacle.

I love Colmans Mustard for domestic things like hot dogs or Reuben sandwiches. For my German sausages I prefer Händlmaier's Würstlsenf Mittelsharfer Senf!
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Re: Racing Mongoose

Post  ian1954 on Sun Nov 09, 2014 9:24 am

fredvon4 wrote:The tank he is using is plumbed for Uniflo so yes there is a ram air effect from the Tee Dee venturi fast fill receptacle.

I love Colmans Mustard for domestic things like hot dogs or Reuben sandwiches. For my German sausages I prefer Händlmaier's Würstlsenf Mittelsharfer Senf!

I had my first Reuben sandwich at Bebe's deli in Chicago last week. It was excellent!
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Re: Racing Mongoose

Post  JPvelo on Sun Nov 09, 2014 9:26 am

ian1954 wrote:I like the wings on this - I always find that being able to see through the covering to the ribs and construction adds something. The finish looks superb.

I would buy it to use the bottle but Colmans mustard tins make excellent tanks!

I like the use of the venturi for fast fill but does it double as an air scoop?

Thank you Ian. The finish is silk span applied with full strength dope then filled with dope/cornstarch/acetone sanding sealer then dc540 primer. The red is rustoleum painters touch. It went on thick and ran so I imediately wiped it off, waited two days and wet sanded the whole mess back down. Total PITA!
The mustard was dumped as it was only purchased for the bottle, I like a good Dijon. I do use Colman's in my crab cake recipe. I'll have to mix some up and try as a condiment.

How many tanks do you think I can get from the 16 ouncer!


The spicy Jim.
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Re: Racing Mongoose

Post  JPvelo on Sun Nov 09, 2014 9:34 am

I'm going to take some of these home for tanks, they seem slightly thicker than the Colman's tins.


Last edited by JPvelo on Sun Nov 09, 2014 9:35 am; edited 1 time in total (Reason for editing : Spelling)
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Re: Racing Mongoose

Post  ian1954 on Sun Nov 09, 2014 9:58 am

There used to be many sizes of Colman tins. This was the most popular at around 50cc.



The oval shape allowed it to fit inside a combat wing.
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Re: Racing Mongoose

Post  JPvelo on Fri Nov 14, 2014 3:47 pm

As requested here's video. It's doing 74mph on 60ft lines. I have no doubt it could break 80mph with a different prop but club rules require a top flite 9x6.
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Re: Racing Mongoose

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