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

Modkat (Kingcat like design and build)

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Old 12-22-2006, 03:50 AM
  #201
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Default RE: Kingcat-Like Design and Build

The ones in the email turned out much nicer than the ones posted here ty. RCU must change the photo a little.
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Old 12-23-2006, 11:14 PM
  #202
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Default RE: Kingcat-Like Design and Build

I've can't find the Dave Brown muffler cradle, could you please link to where I can get one?
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Old 12-23-2006, 11:19 PM
  #203
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Default RE: Kingcat-Like Design and Build

here you go

http://www.dbproducts.com/
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Old 12-24-2006, 11:22 AM
  #204
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Quote:
I've can't find the Dave Brown muffler cradle, could you please link to where I can get one?
I forgot to say that this item is only required if you run the muffler through the fuse with a rear exhaust engine.
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Old 12-25-2006, 12:27 AM
  #205
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Default RE: Kingcat-Like Design and Build

Wing Construction 7

Summary

Other wing's done! Now, the hard work begins with finishing the fuse and boom plug. Here's some pics of the parts compared with their CAD renditions.



Figures 1 & 2



Figures 3 & 4


What's Next?

1. Lay up another coat of 5oz fiberglass on the fuse plug

2. Start sanding [:@]


More to come,

Mods
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Old 12-25-2006, 04:32 PM
  #206
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Default RE: Kingcat-Like Design and Build

Congratulations on "MODEL OF THE YEAR" Kelvin, wishing you and your family all the best for the holidays.

Ants
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Old 12-26-2006, 12:55 AM
  #207
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ORIGINAL: Ayrtonsenna

Congratulations on "MODEL OF THE YEAR" Kelvin, wishing you and your family all the best for the holidays.

Ants
Thanks, to you the same. On a side note, my family should be +1 pretty soon.

I'll probably fly a few victory laps around the field with the Skybolt when I get around to it.

__________________________________________________ ____________________________________


Fuse Plug 5


Summary

I know what you're thinking; he's building on Christmas? I'm expecting my first child any-day now so I'm getting all the work in I can while I have the time [sm=wink_smile.gif].

Began work on the boom plug and figured out that belt sander is one of my best friends. Using the sander and templates cut down the rough shaping stage to about two hours. I did finish glassing the fuse plug and should be able to shoot the first coat of primer tomorrow.


Construction

First, I glassed the underside of the fuse plug with another layer of 5 oz fiberglass (figure 1). Then, printed out a few full scale images of the tail boom (figure 2).


Figures 1 & 2


Second, I cut out the boom shape, minus the fin, and glued it to a stick of 1" wide basswood (figure 3). Then, I cut around the outline using the belt sander (figure 4).


Figures 3 & 4


Third, I printed out another template of the fin and glued that to the top of the boom plug and sanded it to shape (figure 5). Here is the boom after two hours (figure 6)


Figures 5 & 6


Fourth, Went back to the fuse plug and cut the excess with a razor blade dipped in alcohol. Then, glassed the top (figure 7). For the fiberglass to cure properly I cranked up the heater/dehumidifier and let simmer for 8-10 hours (figure 8). For comparison, it's 50 degrees outside.


Figures 7 & 8


What's Next?

1. Cut out and attach fin

2. Spray first coat of primer on plug

3. Fill/Sand, Fill/Sand, Fill/Sand, Fill/Sand, Fill/Sand......[sm=cry_smile.gif]


More to come,

Mods
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Old 12-26-2006, 09:20 AM
  #208
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Default RE: Kingcat-Like Design and Build

still, as always.......outstanding work kelvin.

if you've read my pm...i might get to see this one fly this spring.
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Old 01-01-2007, 09:06 AM
  #209
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Happy New Year! We had the baby on Wednesday and as you can imagine things have been hectic since then. Should be able to get back in the shop today and make some more on the Modkat.

Mods
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Old 01-01-2007, 12:48 PM
  #210
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Congrats on the addition to your family!

Chris

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Old 01-01-2007, 01:54 PM
  #211
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Congratulations Mod's
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Old 01-01-2007, 03:14 PM
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Congratulations Mod's!!!!!!!!! Boy or gir?
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Old 01-01-2007, 04:06 PM
  #213
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Quote:
ORIGINAL: Ayrtonsenna

Congratulations Mod's!!!!!!!!! Boy or gir?

Thanks, she is a very beautiful baby girl. Got to buy a shot gun now .
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Old 01-01-2007, 05:32 PM
  #214
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Congrats to you and your family , Best Wishes.
I have 2 girls too.........
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Old 01-01-2007, 07:57 PM
  #215
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Default RE: Kingcat-Like Design and Build

Let me know more about this airplane.

congrats on the newborn child! What a great Christmas gift!
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Old 01-02-2007, 10:44 AM
  #216
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Quote:
ORIGINAL: tmw09

Let me know more about this airplane.

congrats on the newborn child! What a great Christmas gift!
The Modkat is a twin boom 90 sized pusher prop aircraft. It was designed using Solidworks 3D CAD. A detailed record of the design process starts at the beginning of this thread. For further information, please refer to the [link=http://www.MRM-RCModels.com]www.MRM-RCModels.com[/link] website.

Thanks,

Mods

__________________________________________________ __________________________________________________ ________________

Fuse Plug 6

Today I applied a few coats of K & B Epoxy primer to the fuse plug for weave filling (figures 1 & 2) . I mixed 1 part white paint, 1 part white primer catalyst, and 1/2 part reducer to achieve a spray able texture. I used the K & B reducer, but after one smell I noticed that is just high grade lacquer thinner; so I'll probably try using that next time since it's cheaper.


Figures 1 & 2


My spray set up is typical with the 8 gallon compressor and HLPV spray gun (figures 3 & 4). Both were purchased from Harbor Freight, but the gun was half off at the time ($32.50). Both worked great for this activity.


Figures 3 & 4


What's Next?

1. The Sanding Begins
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Old 01-02-2007, 10:58 AM
  #217
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Default RE: Kingcat-Like Design and Build

Great work, Mods. Couple of things:

1) You are doing much better than me, it took me years to get back to building after marriage/kids. Guess I'm just slow...

2) Can anyone explain why to go with this style of airframe? What are it's advantages over a conventional tractor sut up or full fuse pusher design in a jet/speed style plane? I'm not slagging it, just curious about the plusses and minuses of the twin boom pusher style airframe.


Mark
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Old 01-02-2007, 11:20 AM
  #218
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Quote:
ORIGINAL: mmattockx

Great work, Mods. Couple of things:

1) You are doing much better than me, it took me years to get back to building after marriage/kids. Guess I'm just slow...
My secret was to let my wife know I was crazy to begin with, so there was no "shock value" when I began RC Modeling. I just make sure to come in the house every 2 hours or so and play with her and the baby for an hour as needed, but I start holding the baby and one hours turns to two, then three, etc.

Quote:
ORIGINAL: mmattockx

2) Can anyone explain why to go with this style of airframe? What are it's advantages over a conventional tractor sut up or full fuse pusher design in a jet/speed style plane? I'm not slagging it, just curious about the plusses and minuses of the twin boom pusher style airframe.

Mark
I've never thought about the benefits of the twin boom/pusher design (I just thought it looked really cool), but I have a few thoughts about a conventional airframe with tractor or pusher engine positions. The difference between tractor and pushers is purely aesthetic, minus prop selection. Propjets with a tractor set ups look less scale than pushers.

On the other hand, if you watch both variants perform you'll see a slight difference in flight characteristics. An F-16 being "pulled" through the air performs slightly different than if it were being pushed through the air (like it should ). Also, prop selections for pushers are very limited, so much so that many modelers buy an oversized prop and make their own.

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Old 01-05-2007, 10:59 AM
  #219
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Congrats with the new arrival !!!

Spend some time with the baby and the family....... the plane isnt going anywhere
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Old 01-05-2007, 11:06 AM
  #220
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Quote:
ORIGINAL: mmattockx

Great work, Mods. Couple of things:

1) You are doing much better than me, it took me years to get back to building after marriage/kids. Guess I'm just slow...

2) Can anyone explain why to go with this style of airframe? What are it's advantages over a conventional tractor sut up or full fuse pusher design in a jet/speed style plane? I'm not slagging it, just curious about the plusses and minuses of the twin boom pusher style airframe.


Mark
In brief...

The technical advantage of a pusher design is that the prop does not generate turbulent flow over the wing/airframe - and the prop can (technically) work better with nothing behind it. Less drag, more effiecent.

For airframe integration design, the reason for a pusher design is to free up the front end of the aircraft for visibility, nose mounted camera/sensors/radar

The twin booms are simply a way of permitting the push design, allowing the engine to be mounted in a location that avoids rotation prop strikes (without obsurdly long landing gear), and also keeps the engine near the aircraft CG. They also work somewhat as a 'shield" or safety barrier - avoids side access to spinning blades. There is no aerodynamic advantage gained with the boom design. If anything, the twin tails are a lot of drag.

Anyway...... its a good general layout - affords good performance, lots of internal aircraft volume (fuel volume if it were larger), and it looks nice
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Old 01-05-2007, 03:14 PM
  #221
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anyone else suddently having problems viewing photos in this thread?

(ok, update.... may be that the hosting site for the images is one that is blocked by the network firewall here at work. I had no problem at home)
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Old 01-05-2007, 05:30 PM
  #222
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Quote:
the prop can (technically) work better with nothing behind it. Less drag, more effiecent.
I'm afraid that I'll have to disagree with you Bob. The biggest problem with pushers is that the prop is now working in very bad air so prop efficiency suffers greatly. In tractor installations, the prop is working in clean air, and while true that the prop wash causes a turbulant flow down the fuselage, it appears that the free stream of air returns to laminar flow between pulses from the prop blades.
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Old 01-05-2007, 11:31 PM
  #223
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Hi Bob,
Now only an old Formula 1 guy would know that.
Al Watson
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Old 01-06-2007, 12:15 AM
  #224
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Hi Al, just trying to keep it real.

People have been promoting pushers since the Wright brothers, yet all the speed records are held by tractor designs. A pusher prop running through the downwash off the wing in an area that is generally turbulent anyway from the fuselage cross-section reduction.
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Old 01-08-2007, 02:12 AM
  #225
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Quote:
ORIGINAL: HighPlains

Hi Al, just trying to keep it real.

People have been promoting pushers since the Wright brothers, yet all the speed records are held by tractor designs. A pusher prop running through the downwash off the wing in an area that is generally turbulent anyway from the fuselage cross-section reduction.
Thanks for the cranium up guys [sm=thumbs_up.gif]. Now I know.

__________________________________________________ _______________________

Fuse Plug 7

Summary

The plug now has more definition and the hatch seam is almost invisible. I learned the "invisible hatch" technique from Mike James' website [link=http://www.nextcraft.com/perfectmatches.html]www.Nextcraft.com[/link]. He is a master of composite fabrication and his site has a virtual smorgasbord of information on the subject. I highly recommend it.


Construction

The plug as been rough sanded since the first coat of epoxy primer, so I figured it would be best to tackle glairing hatch gap before going any further in the plug making process (figure 1). First, I applied a layer of Monokote iron on film to the bottom of the hatch and applied two coats of Part-all wax to the film (figure 2). This was followed by a thin coat of Vaseline as a ghetto style release agent.


Figures 1 & 2


Next, the hatch area of the fuse plug was masked off leaving approximately 1/16" space from the edge to allow for feathering (figure 3). Then, a large batch of west systems epoxy mixed with colloidal silica was applied to the hatch area of the fuse plug (figure 4). Lastly, the hatch was positioned on the fuse plug and the excess filler was removed. The entire plug was sanded again after the epoxy reached full cure (figures 5-8).


Figures 3 & 4


Figures 5 & 6


Figures 7 & 8


Then, a razor blade was passed along the seam making sure to keep the edge perpendicular to the vertical (figure 9). A coat of primer was applied to view any imperfections created by the above steps (figure 10).


Figures 9 & 10


After both components were separated, I tack glued the hatch to the fuse with four drops of thick CA in each corner. The hatch will not be removed again until the last coat of epoxy primer is applied just before the mold is made. Just to give you an idea of how well the hatch fits, here is a view of the hatch installed and then removed. If you squint, you might see the seam and it will only get fainter as the sanding continues.


Hatch Installed vs. Hatch Removed


What's Next?

1. Add filler & sand, add filler & sand, add filler & sand, then primer. Add filler & sand, add filler & sand, add filler & sand, then primer. See a pattern?[&:]


More to come,

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