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 10-18-2006, 11:34 PM
  #101
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Default RE: Kingcat-Like Design and Build

Eh... it looks OKAY

The Force is definitely strond with MODS! Do what you love and the rest will fall into place (except Poker [X(]) I am sure your design will be a raving success and I anxiously await for this thread to bump to the top each time---
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Old 10-19-2006, 11:06 PM
  #102
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ORIGINAL: Razor-RCU

Eh... it looks OKAY

The Force is definitely strond with MODS! Do what you love and the rest will fall into place (except Poker [X(]) I am sure your design will be a raving success and I anxiously await for this thread to bump to the top each time---
[sm=red_smile.gif]

__________________________________________________ _____________________________________________

Canopy is done.

I've added 4 retaining poles, 2 in front & 1 one on each side, to hold the canopy into position (figure 1). The poles are brass tubing with a dowel rod epoxied on the inside (figure 2). This incorportes the brass's stength with the wood flexibility. To make the canopy easy to remove I'm using a [link=http://airpacmodels.com/catalog/product_info.php?products_id=60]Skymaster Hatch Latch[/link] in the rear (not shown in figures-still in route). This would allow the user to access the buttons and fill the tank (both air and fuel) with ease. I could use the traditional "secure with a screw" method, but doing that after each flight would become old really quick [sm=cry_smile.gif] and for $3.95 it's dirt cheap! My plan is to include all of the unique components in the kit (all wood and fiberglass parts) and include a list so the user can purchase the comercial items separately. This will help keep the purchase price down.

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Old 10-20-2006, 02:19 PM
  #103
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Default RE: Kingcat-Like Design and Build

Very impressive, I've been looking for a bobcat 50 but there all sold out and not quite what I'm looking for. Your plane is exactly what I'm looking for.

I'd like to be put on your backorder list but money is tight, currently at UTA (Arlington, TX) for aerospace engineering.

I see you stated the price in the ballpark of $100-$200, if it does end up in the price range with retracts and fiberglass wing tubes plz put me on the list!!! Also, could you make the kit for a Jett 90L with muffler in the fuse like yours? I'm in no hurry so Jan 07 lets me start my charity for my ModKat.

All I can say is awsome for them letting you use the name ModKat and building a plane almost identical to the bobcat.
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Old 10-20-2006, 05:36 PM
  #104
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ORIGINAL: coolitdown40

I see you stated the price in the ballpark of $100-$200, if it does end up in the price range with retracts and fiberglass wing tubes plz put me on the list!!! I'm in no hurry so Jan 07 lets me start my charity for my ModKat.
Hey thanks and welcome to RCU! To answer your questions: the Modkat will not come with the retracts required to complete the kit. They must be purchased separately from Spring Air or Robart. Right now, I will include the fiberglass wing tubes with the kit. They are not that expensive and can be purchased in bulk. The price should still be in that ball park, but it all depends on how much fiberglass and kevlar is required for each part. Even if the price is off, it would not be feasible to sell it for an outlandish price. A wise man once said: "Wood is cheap, but fiberglass is a kick in the b@!!$". Your on the list.

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Old 10-20-2006, 05:57 PM
  #105
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Default RE: Kingcat-Like Design and Build

Thank you very much I'll be looking farward to seeing the final result, nice job so far.
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Old 10-21-2006, 04:20 AM
  #106
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Default RE: Kingcat-Like Design and Build

Why would you need some kevlar [sm=confused.gif] ? Do you already think you're on the heavy side ? If you go for it, be prepared to buy expensive ceramic scissors [X(]
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Old 10-21-2006, 11:40 AM
  #107
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ORIGINAL: Strykaas

Why would you need some kevlar [sm=confused.gif] ? Do you already think you're on the heavy side ? If you go for it, be prepared to buy expensive ceramic scissors [X(]
A sleeve of Kevlar will be layed-up in-between the layers of fiberglass to reinforce the high stress areas (i.e. landing gear, where the boom meets the fuse, etc.). I would prefer to use carbon fiber but it's waaaay expensive and Kevlar is the next best thing. While it's not as stiff as carbon fiber it, will add considerable strength to those areas. I never mind buying expensive tools . My dad explained it to me like this: "Would you go to a doctor who uses cheap operating equipment? Well then, if you plan on doing professional grade work, buy professional grade tools." After every project I find this to be more and more true.

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Old 10-22-2006, 10:50 AM
  #108
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You might have addressed this before but did you consider having the ability to retract the landing gear in towards the fuselage instead of forward. Since your already having to reiforce the spars could you of done that instead?
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Old 10-22-2006, 11:36 AM
  #109
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ORIGINAL: coolitdown40

You might have addressed this before but did you consider having the ability to retract the landing gear in towards the fuselage instead of forward. Since your already having to reiforce the spars could you of done that instead?
No trouble at all. True I could have the retract toward the fuse but I would have to cut into structurally necessary components. I'll explain, the main reasons I didn't have the retracts go toward or away from the fuse are:

For all explanations please refer to figure 1

-- Not enough space readily available without having to cut the engine mount spars. These two spars will handle tremendous amount of stress from the Jett 90. That's why they are tied into the wing tubes and all major components of the wing. Because of this, I am a little too chicken to start cutting them. I could also place the booms farther apart but the width required makes the plane look really goofy.

-- I'm using Robostruts for the mains and they can be cut to a minimum length of 4 5/8in and the tires are 2 1/4. Overall length of the assembly in the "down position" is 5.34in. This constraint also reinforces the above statement.

--- Prop Clearance. I need at least 1 in of prop clearance on rotation to avoid a prop strike. Therefore the strut length must be longer.

-- Looks cooler this way
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Old 10-22-2006, 12:14 PM
  #110
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I'm new to retracts so could you please recommend which Robostruts would be best for the Modkat?
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Old 10-22-2006, 12:42 PM
  #111
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ORIGINAL: coolitdown40

I'm new to retracts so could you please recommend which Robostruts would be best for the Modkat?
Sure. For the mains I used the 651L & R (left and right). The nose gear can be L or R. The retract system can either be the [link=http://www.retracts.com/]Spring Air 101[/link] or [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&W=000614822&I=LXJZD3&P=K]Robart 501 System[/link]. I'm using the Spring Air 101 firewall mounted with Robart Robostruts 651s for the prototype but I'm seriously considering the Robart System. Functionally they are the same (spring down, air up) but the Robart is 1/3 cheaper.

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Old 10-25-2006, 02:27 AM
  #112
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Made a little more process on the Modkat with the completion of the canopy and near-completion of the twin booms. I could have probably finished both yesterday, but I've been busy getting the MRM Models website up and running. Should be about two more weeks.

I changed the canopy design to incorporate two hatch latches, one in front one in rear, and beveled the front end at an angle (figure 1). This will make the process of attaching and removing the canopy a lot faster by just having to push both latches toward the center and pull up. Doesn't get much simpler than that. The boom took a little bit of planning (figure 2). All the servos are mounted internally. Where the wing is in contact with the booms there are three plywood formers, the rest are balsa. The paper tube in the center is to run the servo wires from the elevators and rudders to a hole in the wing. The skin will be a laminate of balsa sheet sandwiched between fiberglass. I've used this process before and it yielded some unbelievably strong composite skins with minimal weight gain. This will also help to lower the cost by reducing the amount of Kevlar (EXPENSIVE [&:]) required for each part.

I'm developing a four phase test plan to have the Modkat in production by Jan-Feb 07.

Phase 1- Model the aircraft in Realflight and do the initial flight tests in a safe virtual environment.

Phase 2- Alpha Testing. Build a prototype and verify flight test data gained from the SIM. Ever heard the expression "don't fly the "A" model of anything". This is why, it's the first hack of the production model. There are problems and most are addressed in this phase.

Phase 3- Beta Testing. Issue the kit in a limited release to gain feedback on construction, performance, and overall pros and cons.

Phase 4- Full Production

I usually don't assemble an airplane until all of the subcomponents are complete but I just couldn't help myself (figure 3). Still have to complete the rudders, but everything fits as designed. I still might tweak some of the dimensions to smooth out the appearance. Initially the dimensions were stated as 60in L x 50in W, the CAD rendition is pretty close [sm=shades_smile.gif] and the Alpha model should be as well (figures 4 & 5). Now I have to start designing the plugs [&:].

More to come,

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Old 10-25-2006, 10:57 AM
  #113
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Default RE: Kingcat-Like Design and Build

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Phase 1- Model the aircraft in Realflight and do the initial flight tests in a safe virtual environment.
You think you might release the Realflight model for other to try? I know it won't be like the real one but it would still be nice to play around with.
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Old 10-25-2006, 04:05 PM
  #114
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Default RE: Kingcat-Like Design and Build

Really impressed with the plane and your work congratulations, I want one, my v-diamond will jealous, please add me to your list and please consider the retracts and a mount for a standard .60 motor Like the magnun or evolution,,,,,consider also how will you ship the plane to my country Lima Peru south america and the costs, my email is wcmeier@yahoo.com
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Old 10-25-2006, 04:30 PM
  #115
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Default RE: Kingcat-Like Design and Build

I would prefer a Reflex XTR one. I doubt you will have any time for these
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Old 10-25-2006, 11:24 PM
  #116
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ORIGINAL: arck

Really impressed with the plane and your work congratulations, I want one, my v-diamond will jealous, please add me to your list and please consider the retracts and a mount for a standard .60 motor Like the magnun or evolution,,,,,consider also how will you ship the plane to my country Lima Peru south america and the costs, my email is wcmeier@yahoo.com
Thank you. The Modkat should be able to perform with engines in the 0.75-0.90cc range. There are similar type designs (nitromodels) that fly on a 0.46cc, but it really depends on your flying style. The body type was originally designed for turbines and this is why I choose to design it mainly for the Jett 0.90. With this engine the plane really comes alive and accurately demonstrates the plane's great flight characteristics. Shipping to Peru is between $20-$50 USD. I will know the final price of the kit once ALPHA model testing is complete.

Your on the list,

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All,

Are having fiberglass wing tubes all that important to you when considering the kit? The reason I'm asking is I found a supplier that can sell me Phelonic Tubes at cost. The phelonioc tubes are 90% less expensive than the fiberglass tubes and would further reduce the kit price.

Thanks,

Mods
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Old 10-26-2006, 12:27 AM
  #117
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Default RE: Kingcat-Like Design and Build

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All,

Are having fiberglass wing tubes all that important to you when considering the kit? The reason I'm asking is I found a supplier that can sell me Phelonic Tubes at cost. The phelonioc tubes are 90% less expensive than the fiberglass tubes and would further reduce the kit price.

Thanks,

Mods
To me fiberglass is not that important to me just because its fiberglass but rather that I know the plane will be very strong and be able to withstand much more. Whatever you use I will get the kit but I would much rather prefer fiberglass.

This must cost a lot for you to be concerned, how much of a jump in kit price are we talking because if it still stays below 200 after shipping I'm game (heck even if it was more than 200 I'd probably still get it)? Also, would there be a significant drop in performance or abilities if phelonioc were to be used?

One last thing I'd like to clarify is retracts. Will the kit will have the parts included to add retracts?

edit: by parts I don't mean the retracts themselves but rather the reinforced parts for the wing.
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Old 10-26-2006, 09:12 AM
  #118
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Default RE: Kingcat-Like Design and Build

Thanks Mod, I'm excited for the maiden,,,,,,, for the time I will buy the motor between .75 and .90 and will stay tune in this thread very closely,,
Thanks,,,,,,,
wm
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Old 10-26-2006, 09:44 AM
  #119
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Default RE: Kingcat-Like Design and Build

Quote:
ORIGINAL: coolitdown40

This must cost a lot for you to be concerned, how much of a jump in kit price are we talking because if it still stays below 200 after shipping I'm game (heck even if it was more than 200 I'd probably still get it)? Also, would there be a significant drop in performance or abilities if phenolic were to be used?

One last thing I'd like to clarify is retracts. Will the kit will have the parts included to add retracts?

edit: by parts I don't mean the retracts themselves but rather the reinforced parts for the wing.
The main reason I choose fiberglass is because I wanted to try something different. They are not structurally needed. I'm really trying to keep the price hovering very closely to $200. It costs $20 (this includes shipping) for a set of fiberglass wing tubes for the Modkat. I can get the phenolic tubes (which are plenty strong) for $2. That's 18$ bucks I can knock off the kit!

Mods

EDIT:
Quote:
One last thing I'd like to clarify is retracts. Will the kit will have the parts included to add retracts?

edit: by parts I don't mean the retracts themselves but rather the reinforced parts for the wing.
The gear reinforcements will be included in the kit.
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Old 10-26-2006, 10:03 AM
  #120
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Hey guys RCU has two Jett 90 engines for sale, 325 each look [link=http://www.rcuniverse.com/market/item.cfm?itemId=232546]here[/link]
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Old 10-26-2006, 10:14 AM
  #121
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Default RE: Kingcat-Like Design and Build

That's a deal!

Conventional side exhaust engines can be used on the Modkat, but a rear exhaust engine would produce optimal results (less drag & clean up).
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Old 10-26-2006, 06:15 PM
  #122
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ORIGINAL: Mods-R-Me

The main reason I choose fiberglass is because I wanted to try something different. They are not structurally needed. I'm really trying to keep the price hovering very closely to $200. It costs $20 (this includes shipping) for a set of fiberglass wing tubes for the Modkat. I can get the phenolic tubes (which are plenty strong) for $2. That's 18$ bucks I can knock off the kit!

Mods
Well if fiberglass is not structurally needed then whatever is cool with me.

Again, awsome work you have done and can't wait to see the final project fly.
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Old 10-26-2006, 11:14 PM
  #123
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Default RE: Kingcat-Like Design and Build

Rudders done (figure 1). It has the same "hidden hinge" design as all the other control surfaces (figure 2). The servos will also be mounted inside the boom.

Now it's on to the boom and fuse plugs. They will be designed in CAD as well and then sent to the laser cutter. In the mean time I'll be building a home made foam cutter and getting the shop ready for some real work [sm=shades_smile.gif]. You'll start seeing less CAD renderings and more "reality" shots. RC is a great hobby. Never get board.
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Old 10-26-2006, 11:42 PM
  #124
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Default RE: Kingcat-Like Design and Build


Quote:
ORIGINAL: coolitdown40

Quote:
Phase 1- Model the aircraft in Realflight and do the initial flight tests in a safe virtual environment.
You think you might release the Realflight model for other to try? I know it won't be like the real one but it would still be nice to play around with.
Ditto!

So, how much is this bad boy going to co$t?
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Old 10-27-2006, 12:16 AM
  #125
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ORIGINAL: Kmot


Quote:
ORIGINAL: coolitdown40

Quote:
Phase 1- Model the aircraft in Realflight and do the initial flight tests in a safe virtual environment.
You think you might release the Realflight model for other to try? I know it won't be like the real one but it would still be nice to play around with.
Ditto!

So, how much is this bad boy going to co$t?
I really will not know that until the prototype is built. I'll have a rough idea in a month or so. It depends on how much material is used for the fiberglass parts.

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