Guillow 501 P40 Warhawk build

[cranialrectosis]

Having just finished a VERY simple Fly-Boy build, I have stepped up to the next Guillow level of build competence, the 500 series warbirds.

The P40 is one of the ultimate US Warbirds. This is the plane that invented modern air to air combat over the Burma road when guys like Chennault and Boyington took the fight to the Japanese on behalf of the Chinese in the late 30s.

Underpowered and overweight the P40 had a very minimal role by the end of the war. But its iconic lines and the sharkstooth paintjob the Flying Tigers (AVG) used have enshrined the P40s high regard by flight and model enthusiasts for 80 years.

Don't let all that fool you. I suspect mine will last less than a week, particularly if I attempt to put a motor and servos in this thing.

I am thinking of putting a Suppo 1510 2300kv motor in it and running a 5030 prop on a small 2S or 3S lipo if I can figure out how to fit electronics into a 16" wingspan model.

At any rate, here is the mostly completed main fuselage frame.

 

[dpalmer146]

P-40

Made a Guillow P-40 when I was a teen. Never did get it to fly on rubber band power. would love to give it a try with all of the micro electronics now available. Be sure and build it light, pretty sure it will be pretty fast.

 

[cranialrectosis]

I have been waiting for something called a CA hinge. Tonight I am learning how to use it to modify the tail section.

I still don't really know what lipo I want to use. It's gonna have to be small to keep this thing light and (I agree it will likely be) fast.

The 2.5g servos are here and I have some tubing coming in to help guide the pushrods down the inside of the fuselage.


This is what I love about our hobby. There is always more to learn.

 

[willsonman]

I had a Guillow's corsair kit that I passed along to another forum member. I had done a lot of research to make the conversion but then got into bigger models. I would stick with a 2S configuration. 3S would be overkill and more than likely make your wing loading too high for it to fly well. Build the tail as light as you possibly can! If you are able to, get some contest grade balsa for the tail pieces and re-cut them. This will save a lot of weight over the supplied balsa in the kit. For covering, I would highly recommend solite covering film. It will weigh much less than usual covering films like monokote or the like. If you have a local print shop, hit them up for a material modelers call doculam. It is a film used to laminate documents that has a heat-activated adhesive. It weighs very little like solite. The disadvantage is that you will have to treat it with primer (recommend glidden gripper) and then add paint. It does not shrink as much as other covering films so its less forgiving on corners and such.

Do a google search for a conversion thread. There are many out there. For hinges I would recommend old floppy disks. They are lighter and more flexible and less likely to strain your tiny servos than a CA hinge. Find a motor well-suited for a 7x4 prop on 2S.

Best of luck! I'll be watching this one.

 

[cranialrectosis]

Thanks for the suggestions willsonman. I am pretty new at this aspect and learning heaps every day.

I am really concerned that my 15g motor will be too heavy already. I have a stack of 1804s and 1510s at 2300kv that should spin a 6" or 7" prop on 2S just fine but 15 grams....

Plus the lipo, ESC and 3 or 4 servos, I am really taking my time trying to give myself options on where to put hardware so I can balance this thing and I suspect I will be pushing weight limits as it is.

I was originally considering tissue to cover this but after the FlyBoy hit the sprinkler on the maiden, I have been considering something a little more waterproof. I will look into solite.

Do you really still have floppy disks? I abandoned printers and disks and MSExcel in the 90s.

There is a conversion thread I found on RCGroups that I liked. I can't find it anymore but you are right, there are a ton of them out there. I find that a LOT of them end up tail heavy due to servo placement. Maybe that 15g motor will pay off after all.

 

[willsonman]

Yeah, I scrounge floppies from yard sales and anywhere I can find them. Never use them for computing. Remove the plastic outer shell and recycle that bit. Just save the insides.

 

[roversgonemad]

RC Groups is a dog eat dog world for people new in the hobby, but they have some great conversion threads over there. I am sure there are some threads solely dedicated to the P-40. A lot of guys use the guts from an Horizon UMX plane. the guts from something like the UMX Carbon Cub would haul your P-40 through the sky quite nicely. That is an expensive option though.... I have Guillows Hellcat that I was planning on converting, and a Dumas Wildcat. The Dumas kit has a much better grade of wood, so it is better suited to RC conversion, but the Guillows kits are still good little kits, you just have to build lite. While things like Solex are great, don't forget about tissue. It's not quite as durable as a film type covering, but it can be pretty light if you are conservative with the dope. Doped tissue also accepts paint fairly well. Just some thoughts.

 

[cranialrectosis]

Thanks for the tip roversgonemad. The Carbon Cub idea led me to its description and may answer the question I had about which lipo to use. Looks like a 180mAh 2S 20 C will do it. I was thinking the 350mAh 30C was probably too big and looking for options.

I may just stay with tissue for this. In all honesty I am a poor pilot and I don't expect this will last long once it gets airborne.

 

[cranialrectosis]

I have the tail section cut and spot glued.

I am using two 1/16" balsa sticks glued together (in the clamps and as the base of the tail in the photo) on either side of the CA hinges (not pictured). Confused?

 

[cranialrectosis]

The tail is split to allow for elevators. I will be adding a balsa filler to support the control horn on the elevator.




I got a few more minutes to tinker.

 

[cranialrectosis]

I found the build I had in mind when I started this.
http://www.rcuniverse.com/forum/kit-building-121/11601009-guillows-501-kit-p-40-warhawk-build-up-micro-rc.html

 

[cranialrectosis]

A little gluing and sanding later.

This shows how I think the CA hinges are going to be placed.




Do you add covering such as tissue or monokote before or after you add the control horns? Thoughts?

Also any thoughts on center cutting 1/16" balsa to seat the CA hinge in the wood.

Edit: Helps when I attach the picture.

 

[willsonman]

I would cover prior to the control horn and hinging. Looks good. For the hinges I would just use the thinnest razor I can find... and be very careful.

 

[cranialrectosis]

Thank you, wilsonman.

I concur. I am rebuilding the tail with 1/8" x 1/4" beams where the hinges will be. I will slice that with the razor, then sand it down to 1/16" or so, cover it and then cut the cover to insert the hinges.

I can seat the parts in my desk vice and keep my fingers away from the blade too.

 

[cranialrectosis]

Got an hour to cut the slits in the beams and test fit the CA Hinges. I also used one to glue together two pieces of scrap by placing the hinge on the scrap instead of cutting slits in the scrap and inserting the hinge. The hinge holds remarkably well, but I question it's durability as it tended to curl when the CA was applied exposing one corner.

I'm glad I took the time to cut.

To make the cuts, I marked the ribs in the tail, stabilizer and rudder on the edges where the hinges will be, put the part into the vice and cut with my #11 X-Acto.




Test fit time. I will need to trim a hinge for the lower horizontal rib in the rudder. Aside from that, the hinges slide easily in and out of the slits.



The last part will be after I cover the wings, to cut the covering and push a pin down the center of each slit to allow the CA a channel. But that is for another day.

Now it's time to start the wings.

 

[roversgonemad]

If you are using an iron covering, with a plane this light, you can also do a covering hinge. Either way, be sure to bevel your hinge line, so it can fold correctly and have no gap. On a plane this small, a gap can be a problem.

 

[cranialrectosis]

Been working on the wing. I just have the three sections built and pinned together but not glued together. Next I need to add the dihedral and connect the wing sections.

roversgonemad, not sure what you mean by 'gap'.

I am thinking of using solite or tissue. Newfangled or oldschool. At the moment it's a tossup.

 

[cranialrectosis]

Just getting it tacked together at this point. I will check it for warps after this first bit of CA dries. But at this point, I have the makings of a wing!

 

[roversgonemad]

You don't want a gap between the fixed portion of the surface, and the control surface. If you have a gap, air can flow through, creating drag due to the turbulence. You want all your hinge gaps as small as possible.

You want it like the top photo, with the fixed and moving surfaces as close together as possible. This is the vertical from an old timer I am building. I am going to use the covering as the hinge hinge on this one. The bottom picture shows the bevel all on one side for the covering hinge, or a tape hinge. It's a little fuzzy, but I think you can make it out.



This is an example of what you don't want, note the gap. This should be as tight as possible without hindering movement.




You are inspiring me to get started on my Dumas Wildcat. I have been wanting to a free flight rubber to electric conversion for a while now!

 

[cranialrectosis]

I'll get the parts as close as I can, but I think that is one pin width apart with CA hinges.

Any thoughts on what happens to a servo installed upside down?