Mo-Best finished (pictures)

LAST EDITED ON May-07-06 AT 10:15 AM (CST)
 
If the weather clears up I will go out and test fly it today.
I started it at the end of last year but it has been on hold while I have been conmpeting with a profile Oriental.
Engine: new SuperTigre 51 ($59 bargan from Tower)
weight: 50oz ready to fly
Area 615sq"
Span 58"
The tank is home made 120cc 30mm square at the front and wedged at the back. let into the fuse by 14mm so that the pickup is only 5mm ourboard of the needle valve. I plan to use some spacers to move the tank outboard to explore the effects.
Silencer is a home3 made tongue muffler with nipple for pressure if needed.
EDIT: The cat is my 6months old male kitten "Spud" who is just preflighting the model
Pics:-

Regards

Mike

Very Nice.....Looks like it won't be under powered might even be to much. Maybe a ST 46 would be more compatable at 50 oz.

Nicely done!

What were the results of the "cat-scan"?

Well the model passed the cat scan and the weather cleared to a beautiful evening. I have had 5 flights with it and it is looking good so far. The main need now is to get the engine run right. Actually the engine has proved to be a real joy to handle. Every start was first flick!! such a change from the B****D B40s I used last year.

I am running a Zinger 11x5 I am not sure if this is the best prop and would welcome others experience. I also think that I need ot change the venturie size. Currently the speed is starting a bit slow and then speeding up too much. It tends to speed up in outside loops.

The CG came out right on the mid point between the plan front and rear limits.

I think that I need a little more ground clearance to give me confidence to hold it down on launch.

The lap times started off at 5.8 on the first flight but sped up to 5.1 by the end of that flight. I was using muffler pressure. I have had a couple of flights with that set-up and the difference in lap time remained rather wide at the beginning nd end of the flights. I then went to a non-pressure skinvent setup and the time difference came down to 0.2sec but I still get the speedup in outside manouvers.

Regards

Mike

LAST EDITED ON May-07-06 AT 07:22 PM (CST)
 
Very Nice Mike!!

Do British cats meow with an accent? I see your's is doing a pre-flight for you.

Beware of cats around models. I once had a cat that chewed the wingtip off of one. The cat lived, but not to a ripe old age!
Steve

Great looking color scheme, very nice model!

I always had trouble with cats and trophies. My sister's stupid feline was alway climing on something and would get on the trophie shelf and walk behind them. Broke the first trophy I ever won. I don't have cats myself, only big goofy dogs!

Very nice looking plane Mike. 11-5 Zinger seems like a light load for the ST-51. Maybe try a 12-5 if you have clearance.

I used to run mine with a 12-6 APC.
How are the lap times upright and inverted? Could be a tank height issue with regards to the faster loops.

Larry's Justice MoBest had a ST 51 in it and was the best flying one he had in my opinion. One of the best profiles I've flown. I've built three myself.

Hi Robert

This is my first "modern" stunt model and so I haven't anything to compare it to other than my Oriental. It really feels smooth to fly It does seem to have a reasonable corner and good tension. I am sure that the engine will be OK but I am just getting to know it. It was fresh out of the box and unrun befoer the first flight so it really is early days yet. I will talk to Larry about how he set up his.

Regards

Mike

Hi Mike,
Why don't you try a Rev Up 12/5 on that bad boy. You will need to up the take off RPM but it will be well worth the effort.

Mike Clark

"Chance Favors The More Prepaired Person"

Mike,
Very, very nice! Great workmanship.
I've had similar problems to the one you describe with pressure from a tounge muffler. If the nipple is located on the flat portion of the muffler, the pressure to the tank can be erratic. The gasses passing over the opening for the nipple can cause a bleed effect that can offset (at least part of the time) the positive pressure effect.

I've run many ST51's and have found them to be excellent stunt engines either in stock form or with slight port modifications.
Depending on intake size, prop load can be very important to controlling the "break". I would reccommend a venturi size of not larger than .280 in a relatively lightly loaded contition such as yours. If your ground clearance will allow it the 12 X 5 prop would be a highly reccommended starting place. If you must use 11 inch diameter props then I would strongly reccommend an 11 X 4.75 or 11 X 5 Bolley or Eather three blade. Even a 10.5 diameter three blade would be significantly better.

If it breaks hard only on outsides then there is probably a tank height issue. The tank would need to be lowered (with the plane in upright condition.
However this begs the question; Are inverted and upright lap times similar. If it is a tank height issue one would expect faster lap times inverted.

If inverted and upright lap times are the same or very similar (within .05 seconds) then the problem may be too much compression. A head shim or two may be indicated.
Simply adding another head gasket will probably help, but it may be more than is needed. Shims in about .003 inch increments would be better.

A very pretty airplane!

Thanks Randy I will make a venturie and try some head shims. The lap times are identical both ways up. I plan to make taller UC legs so that I can try larger props.

Regards

Mike

Mike
I own a ST51 and THIS IS WHERE an ST51 should be!! A lot of guys, myself included, where sticking this motor in planes designed for big 60's. We got just what you would expect, marginal performance. Conversely, a lot guys are sticking 46's in planes where they should be using a 51 like this Mo'best. You got it right!! Hey, a 50 is a 50 and a 60 is a 60 and never the 2 shall meet. I have seen alot of profile Cardinals fly and I always wondered how much better this plane would be if I could stick my ST51 in it. The one down side is that there is a big difference in drag between 70 feet of 015 and 70 feet of 018.

Hmmmmm,
I've used ST51's in two different 700 Sq in airplanes. A Magnum (about 12 years ago), and an original called a 92 Nobler.
Both of these airplanes flew very well and had no under powered issues. I've found the ST51 to be a good replacement for the ST60 in airplanes up to 65 oz or so.
Line length is usually limited to 67-68 ft (center of plane to handle), on either .014 solids or .018 stranded.
The ST51 is a somewhat higher RPM engine than the ST60, but as such produces more power. It does need to use a different assortment of props than the 60.

A couple of interesting things:-

I was told some time ago that a good rule of thumb is 1cc/oz and as my Mo-Best is exactly 50oz the Tigre 51 would seem a perfect fit for the weight. Also I was flying on 12th lines but they were proper steel (Staystrate) not the rather weaker stainless. Actually I was going to make up a set of 15th but the rain in the afternoon made that impossible.

Regards

Mike

Mike,
Fortunately for you, F2B rules allow you more latitude in line size selection than AMA rules do here in the USA.
As you know our rules are based on engine size and demand .015 in stranded and .012 in for solid, for up to .40 engines, and .018 in for stranded, and .014 in for solids above that.
For what it's worth the F2B rules make a lot more sense to me...

Mike,
I am really impressed with your Mo’Best. Exceptionally well done. I especially like the way you built the fuel tank. Did you by any chance do some step by step photo’s of the tank construction? That would be fascinating to see. Did you us standard hand tools?

Larry Price
Edgewood, WA
AMA 586056
AMA 305089

Hi Larry

Thanks for the kind words. The tank was made by hand and I will take some pictures next time

Regards

Mike

Mike,

That's quite nice looking. I didn't know Larry could design something that pretty <grin>

Have fun with it. It sure looks good.

None of Larry's Mo'Bests are that pretty!

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"I have great faith in fools - self-confidence my friends call it." - Edgar Allen Poe

Hey Larry,
I remember a White one in Tucson (probably in the middle to late 90's that was very pretty. In fact, at the time I remember thinking...Why would anyone put that much effort into design and finish for a "stinkin' profile". I've changed my mind (a little) about profiles since then, and your Mo Best was largely responsible for that change.
I have in fact recently decided to build one for P40 with a RO Jett BS 40.
A great design in my opinion. One worthy of historical note in CL Stunt.

Nice cat shame about the plane,
only joking Mike.
Regards corsair man.

Yep he is a really nice cat I will post more pictures (of the cat) if you are not careful.

Regards

Mike

That's a really nice job. I like the Mustang style gear doors too, nice touch!