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Joined: 3/21/2002 From: Ramona,
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Eh... it looks OKAY
The Force is definitely strond with MODS! Do what you love and the rest will fall into place (except Poker ) I am sure your design will be a raving success and I anxiously await for this thread to bump to the top each time---
Posts: 802
Joined: 6/13/2005 From: Antelope Valley,
CA, USA Status: offline
quote:
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 ) I am sure your design will be a raving success and I anxiously await for this thread to bump to the top each time---
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 Skymaster Hatch Latch 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 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.
Posts: 23
Joined: 10/16/2006 From: , TX, USA Status: offline
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.
< Message edited by coolitdown40 -- 10/20/2006 11:39:01 PM >
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Joined: 6/13/2005 From: Antelope Valley,
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quote:
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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Joined: 6/13/2005 From: Antelope Valley,
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quote:
ORIGINAL: Strykaas
Why would you need some kevlar ? Do you already think you're on the heavy side ? If you go for it, be prepared to buy expensive ceramic scissors
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.
Mods
< Message edited by Mods-R-Me -- 10/21/2006 7:40:53 PM >
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Joined: 10/16/2006 From: , TX, USA Status: offline
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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Joined: 6/13/2005 From: Antelope Valley,
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quote:
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
< Message edited by Mods-R-Me -- 10/22/2006 5:37:22 PM >
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Joined: 6/13/2005 From: Antelope Valley,
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quote:
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 Spring Air 101 or Robart 501 System. 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.
Mods
< Message edited by Mods-R-Me -- 10/22/2006 8:23:28 PM >
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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 and the Alpha model should be as well (figures 4 & 5). Now I have to start designing the plugs .
More to come,
Mods
< Message edited by Mods-R-Me -- 10/25/2006 8:47:34 AM >
Printable Version
All Forums >> RC Airplanes >> Extreme Speed Prop Planes >> RE: Kingcat-Like Design and Build 
RE: Kingcat-Like Design and Build - 
) I am sure your design will be a raving success and I anxiously await for this thread to bump to the top each time---
still in route 
and for $3.95 it's dirt cheap! My 
? Do you already think you're on the heavy side ? If you go for it, be prepared to buy expensive ceramic scissors 
. My dad explained it to me like this: "Would you go to a doctor who uses cheap operating equipment? Well then, if you 
) required for each part. 
(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 
and the Alpha model should be as well (figures 4 & 5). Now I have to start designing the plugs