Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Maybe Fast Scat Cat/Jett

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Old 11-24-2007, 02:34 PM
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Barticusmax
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Default Maybe Fast Scat Cat/Jett

OK, so I thought I'd start a thread for my current project rather than "Take Over" another's work.
I have always liked faster planes. Now, lets be clear, I am no racer. I have a strong background in "Sport" and 3D, and know the usual engines and radios fairly well, but some of these racing engines are obviously quite different! Many thanks already due to Bob27 for tons of helpful advice!

Ok, down to the Nitty-Gritty. I am building Scat Cat number 5. the other 4 were all excellent planes, often much better than I was, hence the number of reps!
The smoothest flier had a Max 28 and was quite docile everywhere except straight down, then it really scooted. The rest have all had .40 engines, the best probably being a KB with Perry carb.
With the exception of "Real" racers which I have yet to encounter in any of the 6 clubs I have joined, the cats tend to be among the fastest planes I have seen, hence my choice for my next "Stupid Fast" plane. 3D is great, training others is wonderful, but I am due for some adrenaline these days!
So, I happened upon a Jett QM.40. In 30+ years of flying I have never had a Jett, or a Nelson to call my own. So this opportunity was just the ticket. Well, once it arrived, you can imagine my surprise to discover NO CARBURETOR!! Ok, it's like the control line engines, all or nothing!
Well with some kindly advice (Thanks again, Bob) I ordered a carb, and a prop.
OK, so wayy too much power is now available, so I have reinforced the wing with a carbon fiber spar, and CF strips on top and bottom of the wing. I have also CF'ed the inside of the front end and the wing box.
CG is going to be an issue, so the battery and 3 servos will be in the tail, rather than in the wing box.
Some more CF around the center of the wing, and it will be ready to cover. The aileron servo will be as far aft on the wing as practical, again working toward correct CG with minimal added weight. I figure completion of the wing will help finalize the locating of the equipment in the tail. More to follow!!!
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Old 11-24-2007, 03:57 PM
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Default RE: Maybe Fast Scat Cat/Jett

That's a nice job of inbedding the C/F. With Bob27s' help you are sure to have a weiner. Here's to many hair raising flights!
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Old 11-24-2007, 05:20 PM
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Default RE: Maybe Fast Scat Cat/Jett

My scat cat had an O.S. .46 fx on it, but I don't remember having to put most of the radio behind the wing! I'd put everything where you normally would. If you need a tad of weight put it in the tail - just remove a small section of sheet from the bottom of the fuse as far back as you can - secure it in there and then glue the sheeting back on. This won't affect the aerodynamics at all, and the 'cat's performance won't suffer a bit. Oh yea, if you don't build it with the rudder, that saves a little weight, as well. Whatever you decide, good luck!

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Old 11-24-2007, 05:40 PM
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Default RE: Maybe Fast Scat Cat/Jett

Thanks for the input, Fellas! In my preliminary check, the CG is about 1/2 way back on the tank box, or 3 inches forward of the spec. As the elevator (And Yes, Rudder as I anticipate needing to slip some landings) hardware gets added, it will come back some I am sure, but thats why I mount the majority of the radio later on. I will also be adding hatches and hatch blocks back there too. In it's current state, setting the battery ON the elevator got the CG mostly right.
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Old 11-24-2007, 06:25 PM
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Default RE: Maybe Fast Scat Cat/Jett

Scat Cats were notoriously nose heavy. Most of us trimmed the nose down by 1/2 - 1 full inch. Just curious as to the Upright installation of the motor, if you rotated the head 90 degrees, the muffler should tuck nicely down the bottom of the fuse keeping things much cleaner. I've never seen a Quickie with a Q40 motor, not sure if the plane is clean enough to get everything out of the motor, but you should be looking at least at 150 mph. I'd stick with the lighter props, but your going to want to see at least 22,500 on the ground
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Old 11-24-2007, 07:38 PM
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Default RE: Maybe Fast Scat Cat/Jett

This is motivating me to get back on my scat kat project! Thanks for the pics.
Ken
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Old 11-24-2007, 07:44 PM
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Default RE: Maybe Fast Scat Cat/Jett

ORIGINAL: Barticusmax

OK, so I thought I'd start a thread for my current project rather than "Take Over" another's work.
I have always liked faster planes. Now, lets be clear, I am no racer. I have a strong background in "Sport" and 3D, and know the usual engines and radios fairly well, but some of these racing engines are obviously quite different! Many thanks already due to Bob27 for tons of helpful advice!

Ok, down to the Nitty-Gritty. I am building Scat Cat number 5. the other 4 were all excellent planes, often much better than I was, hence the number of reps!
The smoothest flier had a Max 28 and was quite docile everywhere except straight down, then it really scooted. The rest have all had .40 engines, the best probably being a KB with Perry carb.
With the exception of "Real" racers which I have yet to encounter in any of the 6 clubs I have joined, the cats tend to be among the fastest planes I have seen, hence my choice for my next "Stupid Fast" plane. 3D is great, training others is wonderful, but I am due for some adrenaline these days!
So, I happened upon a Jett QM.40. In 30+ years of flying I have never had a Jett, or a Nelson to call my own. So this opportunity was just the ticket. Well, once it arrived, you can imagine my surprise to discover NO CARBURETOR!! Ok, it's like the control line engines, all or nothing!
Well with some kindly advice (Thanks again, Bob) I ordered a carb, and a prop.
OK, so wayy too much power is now available, so I have reinforced the wing with a carbon fiber spar, and CF strips on top and bottom of the wing. I have also CF'ed the inside of the front end and the wing box.
CG is going to be an issue, so the battery and 3 servos will be in the tail, rather than in the wing box.
Some more CF around the center of the wing, and it will be ready to cover. The aileron servo will be as far aft on the wing as practical, again working toward correct CG with minimal added weight. I figure completion of the wing will help finalize the locating of the equipment in the tail. More to follow!!!
Ok:

You may have the best of both worlds here, looks like a sport jett, but gonna have more rpm. Actually the black pipe is the tipoff, but still available for the sports engines if you need a little more. I have only been around one Q-500 type Jett with a carb added as a cheater attempt. Was more rpm than a L/x motor and seemed to idle and transition pretty good, not quite as good as the sports version, but still good. After a few flights and you get your heart running again, get some altitude and come back a little past 1/2 throttle. If its running clean and well, you are running on the idle circut of the carb for the most part. You should be able to slow it down without risking a flame out. Yes, sort of a dirty trick, but loads of fun for you. Keep it at a reasonable speed, less than 1/2 throttle and encourage the guys to come up and play. Only add throttle as need and you can get away with this for quite a while. Am I that rotten? Well, some of us prefer to call it old and tretcherous, but the same thing.

Would like to see that elevator noodle control rod replaced with a Carbon Fiber unit. ENJOY
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Old 11-24-2007, 08:11 PM
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Default RE: Maybe Fast Scat Cat/Jett

Bob did mention that it may not idle too well, but should be ok above 30%. The rudder and elevator will both be 1/8" CF rods. Having lost one fast bird to elevator flutter, I will avoid it best I can this time. Got all the rpm stuff from Bob too, 7.8" prop as I recall.
Hehe, it only needs to be REEEEEALLLL fast every now and then..LOL but I fly almost alone all week, and will have time to get used to it..
My fear is, no one will catch it even at 30 %! I will be up against 4-stars and some "Hopped Up" trainers, nothing real fast...
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Old 11-25-2007, 09:31 AM
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Default RE: Maybe Fast Scat Cat/Jett

You sly dog(s). Let's hope they don't read this forum!

jt
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Old 11-25-2007, 01:43 PM
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Default RE: Maybe Fast Scat Cat/Jett

Hammer:

It in the genes, a built in personality flaw that screems second is first loozer. Sly, tretcherous etc. is a learned thing that comes about after very few losses. Sort of like keep getting back up when the school bully keeps knocking you down. You can't make up for the 50-75 lbs he has on you, but you can learn to kick crotch well. There are several who do watch our forum, but they are worse than we are by nature and like to look friendly until you turn your back. Yea, you too big D. ENJOY
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Old 11-25-2007, 03:58 PM
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Default RE: Maybe Fast Scat Cat/Jett

Hehe, speaking of treacherous, I am thinking to get another Parkzone cub, make a new wing with symmetric foil, CF spar, and a way too big motor and LiPo, 3d tail feathers and ailerons or warperons (Less obvious) I have decided against the Estes engine for boost, in favor of 3D capability (Maybe even a reverse pitching prop??).
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Old 11-27-2007, 12:15 PM
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Default RE: Maybe Fast Scat Cat/Jett

That looks nice,

but if its not too far along to do it, rotate that engine 90 deg....... you want the cylinder sideways, and muffler under the belly.

upright engines on a Q-500 cause problems with engines going lean in tight turns. Plus the tank ends up about 1" low.

Also, make sure you fiberglass across the firewall on the outside ..... 2" min down each side, and across the firewall.
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Old 11-27-2007, 08:35 PM
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Default RE: Maybe Fast Scat Cat/Jett

Howdy Bob!
Thanks for jumping in!!
I originally wanted to keep the pipe high so it would not hit the ground first if things got ugly, but in addition to lowering the carb, it would reduce the weight imbalance of the off-center pipe. So, I will see how bad a task it will be.
I am not sure if it's obvious from the pics, but the entire front end is layered in 5.7 oz CF. There is a 1/2-3/4" overlap of the 3 sides onto the firewall, and the firewall panel onto the 3 sides too. Do you think the fiberglass is still necessary??
Thanks again for all your help,
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Old 11-27-2007, 08:44 PM
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Default RE: Maybe Fast Scat Cat/Jett

Listen to Bob about the tank height relative to the carb. You will have a hard time tuning your engine and keeping it from going lean. All Q-500 planes have their stuff close to the ground. That is why generally you just hold full up elevator at full throttle and jump them into the air. You just dont spend a lot of time on the ground with them for things to drag much other than on landing.
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Old 11-27-2007, 10:00 PM
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Default RE: Maybe Fast Scat Cat/Jett

What Bob said is very, very important especially on high G pulling planes. You will hear the engine go lean and sag in tight turns if you don't change the engine to horizontal. This is hard on glow plugs and engines. Good catch Bob.
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Old 11-28-2007, 09:57 AM
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Default RE: Maybe Fast Scat Cat/Jett

I can see that you have a great deal of carbon on the inside......
but glass on the outside and across the plywood plate is important for durability on an number of aspects.

Definately consider rotating the engine over. We "racer" guys tend to consider the muffler a nose-skid of sorts Dont worry about getting it dirty.
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Old 11-28-2007, 12:14 PM
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Default RE: Maybe Fast Scat Cat/Jett

Ahem,
Does anyone think I should maybe turn the motor 90'??
Ok OK ALREADY!!!!!
I am easily convinced by even one person in most cases. I have got the point. I will turn the motor!!
Worst case it will probably involve removing the blind nuts that have been assimilated by the CF, but so be it. I will also CF the outside of the firewall to the front box, probably all the way back to the wing box for a consistant surface.
Unless there is any reason NOT to use CF, I have some on hand, but no FG at the moment.
BTW, balsa seems to be an excellent form for CF!
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Old 11-28-2007, 12:22 PM
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Default RE: Maybe Fast Scat Cat/Jett

Vertical Grimmace,
Howdy Homey, Really enjoyed going over your pics! FYI I grew up in Greeley!!
Ever do the "Big Bird Festival"????????
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Old 11-28-2007, 02:21 PM
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Default RE: Maybe Fast Scat Cat/Jett

Yes this last summer. Now we have the Warbirds over the Rockies and that is even better. I have a pylon race everyyear now as well and that did good last year.
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Old 11-28-2007, 03:18 PM
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Default RE: Maybe Fast Scat Cat/Jett

What weight carbon fabric is that? If you have to, just drill out the mounting hole and epoxy in an appropiately sized piece of hardwood dowel.
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Old 11-28-2007, 06:12 PM
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Default RE: Maybe Fast Scat Cat/Jett

5.7 ounce I believe. The issue will be extracting the blind nuts from the CF that is in already. I have in the past used an engraver set all the way high to indent the back of the blind nuts severely, and they will often come loose from the repeated small shocks.
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Old 11-28-2007, 06:34 PM
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Default RE: Maybe Fast Scat Cat/Jett

Why do you have to remove them? Just leave them in there...

If you rotate the engine mount so that the cyl. is in the 8 o'clock position and the muffler is right under the centerline, you won't be able to re-use any of those blind nuts anyway.
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Old 11-29-2007, 05:58 AM
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Default RE: Maybe Fast Scat Cat/Jett

Proptop, Thanks for your input, but the motor mount is such that, turned 90 degrees the holes misalign by 1/8 inch or so. I will need to fill and drill for the new screw locations. The hole pattern might not be too obvious in the pics. Hopefully the rest of the CF and turning the motor will happen this week, maybe not 'til Saturday[]
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Old 11-29-2007, 10:56 AM
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Default RE: Maybe Fast Scat Cat/Jett

Ah...I didn't look closely at your first pic...

I was envisioning a round backed motor mount (like the Q40 type ) that would allow you to rotate the mount more than 90 degrees if necessary.
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Old 11-29-2007, 01:57 PM
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Default RE: Maybe Fast Scat Cat/Jett

...
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