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Old Jun 15, 2014, 10:24 AM
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Canada, ON, Delhi
Joined Aug 2012
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Build Log
TF 65 inch GS P40 balsa kit build

June 20/14 - changed to a build log.

Gathering the parts and pieces together for a TF GS 65 inch P40 Warhawk kit build.

Have flown both TF pre-GS and GS P40s in the past and they flew well. Sold both to get money for other projects. Want another one so here we go.

Will be a P40F of 325 FG "Checkertails" with the colour scheme of Group CO Lt. Col. Baseler, black with red trim and yellow checkered tailfeathers.

Have ordered a 4 inch 3 blade alum spinner from HK. Five meter roll of Black SolarTex on the way from Quebec. Have the 4 inch wheels and 13x8x3 prop.

Powered by an OS .91 FS. Had this engine in a TF P47 12 years ago and it provided plenty of power. Have been flying the engine recently on a .61 Escapade to get it set up again.

Split flaps don't seem to have the same effect in a model as a full size plane so will not include flaps. Eliminates some extra weight.

Lot of complaints about the Robart 615 rotating retracts in this forum and the other one. Have to spend the money on CJM or Sierra rotaters that will stand up to grass fields. Will set up the wing for fixed gear at first but include and cover over retract pockets if I decide to go that route (if I want to spend almost twice the money for retracts as I did for the kit).

Pix below of the 325 FG P40F from Squadron #26 ''P40 In Action''.
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Old Jun 15, 2014, 11:31 AM
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Kansas City
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Just for clarification, GS or Giant Scale normally refers to a wingspan of 80 or more inches.
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Old Jun 15, 2014, 12:49 PM
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Never seen that paint scheme before, that will look good. If you spend the cash for gear, definitely go with Sierra.
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Old Jun 15, 2014, 02:11 PM
Scale Builder
United States, AZ, Litchfield Park
Joined Jul 2002
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Quote:
Originally Posted by Lifer View Post
Just for clarification, GS or Giant Scale normally refers to a wingspan of 80 or more inches.
Just for clarification I believe "GS" stands for "Gold Series" (Gold Edition, same thing) in this particular instance.
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Old Jun 15, 2014, 02:25 PM
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United States, AZ, Litchfield Park
Joined Jul 2002
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Quote:
Originally Posted by erie_flyer View Post
Split flaps don't seem to have the same effect in a model as a full size plane so will not include flaps. Eliminates some extra weight.
I found the flaps on my TF P-40 to be quite effective and I would definitely recommend them. I guess much depends upon the final weight of your airplane and what type of fields you generally fly out of.

Quote:
Originally Posted by erie_flyer View Post
Lot of complaints about the Robart 615 rotating retracts in this forum and the other one. Have to spend the money on CJM or Sierra rotaters that will stand up to grass fields. Will set up the wing for fixed gear at first but include and cover over retract pockets if I decide to go that route (if I want to spend almost twice the money for retracts as I did for the kit).
I've had a TF P-40 as well as a couple of Hellcats with Robart 615 retracts and never had a single failure with them. They do have some slop when down and locked though. I only fly from paved or hard packed dirt surfaces which may make a difference. I must add though that one of my Hellcats is almost 12 pounds and the Robart gear have never given me issues despite the extra weight. (They are only rated for 10 pounds) I've also had a TF P-40 with CJM gear and while they functioned reliably they had massive amounts of slop both in the up and down locked positions and they were very easy to bend. I'm currently working on another Hellcat for which I have purchased the Sierra gear and they are light years better than either the Robart or CJM units. Just FYI, Robart has just released an electric .60 size 100 degree rotating unit as well, the 810.
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Old Jun 15, 2014, 03:20 PM
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Chad: Thanks for the tip on the Robart 810 series. I need to get out the ruler and start measuring the mounting area in the TF 60 size Corsair. The 615's I had in my first Corsair worked for the most part. They were also sloppy when down and picky about how much pressure was needed to make them work. Plus I never really liked how they slammed home in both directions. I guess I just like electric retracts better. At least in this size. Problem was that untill now LADO was the only real choice for this plane and finding them is like finding a 4 leaf clover. At least for me.
These look nice and sturdy so extra weight on a 60 size plane shouldn't give them any trouble at all.


EDIT: Well they are way to big for the 60 size Corsair ARF. Probably to big for the 60 size P-40 as well, although the P-40 won't have a wing joiner/spar in the same location to deal with I think wing thickness at the mount and at the rear of the retract motor will cause the same problems. They look great for something in the 74-74" w/s range though.
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Old Jun 15, 2014, 04:54 PM
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Yes, the GS stands for Gold Series or Gold Edition. I have seen it said both ways in the Forums.

I have used a variety of mechanical rotating retracts over the past 30 years. The weak point is the linkage that causes the rotation. Can`t take the stress. None of them stood up to regular use on grass fields. I have never flown off pavement.

EFlite does not make a .60 size electric rotater. Could drill out the .40 size to take 3/16 rod I suppose but will it lift a 4 inch wheel?

Chad...thanks for the tip on the Robart 810. Anyway I will start with fixed gear so the maiden has one less thing to concentrate on. Will build structure for retracts into the wing and cover it over. That is one of the advantages of building a balsa kit. The airframe can be easily modified and/or strengthened.

Thanks for the interest guys. Will be heading into Toronto the first non-flyable day this week to buy the kit.

Edit: I see the Robart 810s have an intro price of $210 U.S. which includes the control unit. Will inquire about them at the LHS when I pick up the P40 kit.

Bill
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Old Jun 16, 2014, 04:03 AM
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I was going for the more common reference. Apologies for any confusion it may have caused.
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Old Jun 16, 2014, 07:49 AM
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Further thoughts on split flaps. I have built these into R/C planes over the years .............a TF GE P40 and a TF GE "Hollywood Zero". Besides not seeing the same beneficial effect as slotted flaps in a P51 or P47 which I have also built there is a more tangible problem. Making the split flaps lie flat and stay flat. I flew an EFlite Texan ARF that came with split flaps. They were flat out of the box but gradually warped with use.

The common problem with a balsa kit is the thin 1/16 ply usually provided for the flaps being warped before even being punched out of its sheet in the kit. Its a roll of the dice what comes out of the box. Solution is going to the LHS and buying a flat ply sheet (hopefully). Then once installed the flaps have to stay flat over the years. Wood can absorb moisture and if you live in the type of area I do going from hot humid conditions in the Summer to cold dry air in the Winter the split flaps can warp. Or worse, only one will warp causing a trim problem.

Some build and use split flaps with success and more power to them. Myself, based on personal experience, unless the plane will be entered in a scale contest, I don`t think they are worth the hassle.

Edit: Looking again at the Robart 810 rotating retract promo, it appears the $210 price does not include struts. Robostruts would also have to be purchased. Am I interpreting this correctly? http://robart.com/collections/retrac...ectric-retract

Bill
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Old Jun 18, 2014, 07:34 PM
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Wowsir.........south Ontario was on the top end of the storm system that went through Nebraska. Got three F2s up here. Hit a village hard. Trevor, are you still in one piece up in the boonies?

Went into the Big Smoke today and picked up the TF P40 balsa kit. Started by going through all the die-cut sheets, labeling each punch-out and sorting them by sheet number.

TF calls this a P40E model but as identified in post #1 this will be a P40F variant. The F series had a Rolls Royce Merlin XX engine made by Packard. The Merlin up-draft carb had the carb air intake at the bottom of the cowl opening which eliminated the long carb intake on top of the cowl.

The previous P40 variants had various nicknames like Tomahawk and Kittyhawk. The USAAF called the F series Warhawk and this name was subsequently applied to all P40 variants.

Above info from Squadron #26, "P40 In Action", p. 22.

Below is a pix of the Merlin carb intake. Note the difference on top of the cowl between the E and F variants.
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Old Jun 20, 2014, 07:28 AM
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Did the reverse roll of the plan sheets and let sit overnight so they would lie flat when placed on the building board. Sorted the hardware bag into small plastic containers as to type, material and size.

Looked through the 25 sheets of 1/16x3x30 balsa used for wing and tailfeather skins. It can be a total pain making up the skins if the sheets are all different grades from different logs. TF did a nice job here. All good quality balsa - 23 sheets medium soft and cut from the same log, the other 2 sheets a little harder and cut from the same log. Sheets straight with no warps. The skins should go together nicely.

For now following the order of steps as per the manual. Started the build with the stab. Layed the plans over the 2 inch sheet of styrofoam I use for a building board and protected the plans from glue with a sheet of waxed paper.

The medium grade stab ribs punched cleanly out of their sheets. TF is using sharp stamping dies and there is no crushing of the balsa, just clean cuts. The ribs have jig tabs that align them properly over the plans. LE is cut from shaped stock and the TE is laser-cut in a balsa sheet. Thin and medium CA glues the various components together and the build goes quickly. Care is taken to have square pockets for the elevator balance tabs. Sturdy fore and aft joiners connect the two stab halves. Go over all the joints again with medium CA and let sit overnight over the plans with light weight on top to ensure flat.

Pix below of the stab so far before final trimming and sanding.
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Old Jun 21, 2014, 07:55 AM
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Trimmed the ends of the stab`s TE and LE. Sanded TE and LE tops to contour of ribs.

Glued the skin sections together for the stab. Prefer to use aliphatic woodworking glue. Slower than CA but no fumes. Hinge the balsa sections together with masking tape, open the seams, run a bead of aliphatic in the gaps, close, wipe with paper towel, sit on flat surface tape side down, light weight on top, let dry overnight. Next morning remove tape and sand seams.

Sheet stab top first. Dry fit the two top skin halves for good center join. Medium CA on LE, bond skin to LE, run bead of aliphatic on top of ribs, medium CA on TE, pull skin down and bond to TE. Place stab flat on jig tabs and weigh down with bags of lead shot that mould to contour of skin surface. Let sit overnight. Next morning trim skin all around. Don`t remove skin from elevator balance tab pockets until tip blocks glued in place.

Pix below of the top skin stages.
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Old Jun 22, 2014, 10:44 AM
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To skin the stab`s bottom have to cut off the rib jig tabs then sand all to the same airfoil as the top. Have to glue the two bottom skin halves one at a time so no warp induced. While the glue on the stab`s bottom skins was curing, framed up the fin. Built the same way as the stab on the rib jig tabs. Went fast and applied the left fin skin with CA and aliphatic. Weighed down with a shot bag while glue cured.

Moved on to the rudder. Extensive lightening holes are punched in the rudder base (and elevators) in the P40 kit. I built the 63 inch TF Spitfire kit last Winter which had oversized tailfeathers (for deadstick) which produced a tail heavy Spit. I knew I would be using a heavy gasser engine in the Spit so that didn`t bother me. Total weight of the Spit`s fin/rudder/stab/elevs was 5 oz. Will be interesting to see the total weight for the P40 tail structures.

Framed up the rudder then switched back to the fin. Removed jig tabs, sanded smooth and applied right fin skin. Let sit overnight. Next morning placed the rudder against the fin to guide the gluing of the top fin block which forms the rudder balance tab pocket.

Now that I have glued on several small balsa blocks in various areas I can see the same "problem" that I have worked with in balsa kits for 40 years. Matching blocks do not match in density and hardness. For instance in the two rudder bottom blocks one is medium soft while the other is medium hard. So far all of these blocks are small and won`t pose a problem with weight, shaping and sanding but if this happens in large blocks such as wing tips it can affect the final weight. I have checked the P40 wing tip blocks and they are both medium soft. In the Spit I built the large wing tip blocks were hard and heavy so I substituted with dense blue foam.

Pix below of the fin and rudder. Lot of shaping and sanding to do on the rudder.
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Old Jun 22, 2014, 12:26 PM
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upland CA
Joined Dec 2004
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I will be watching close! I just picked up a part built kit here on RCG. Thinking of going electric on mine but not sure yet as I have a few engines that would work well in this.
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Old Jun 22, 2014, 02:15 PM
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Canada, ON, Delhi
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Turbo..........I have built two of these TF P40s in the past, pre-GE and GE. The GE was a better flyer which would be expected. Just make sure the main axles are forward of the wing LE for ground handling.

The main concern with the TF builds is tail heavy. The tail surfaces are intentionally oversize to help with deadstick landings. This upsets some scale purists but it is either oversize or have a flying brick on your hands if an engine flames out at altitude.

If you are going electric I would recommend replacing balsa blocks with dense blue or pink foam to reduce weight. Keeping the weight down might also help with rotating retracts if you decide to go that route. On a grass surface the linkage that causes the rotation takes the full stress of a landing. I have yet to use a set of rotaters that will stand up to regular use. Eliminating split flaps will save some weight as well. I don`t think split flaps are effective in models. There are those that will disagree but I can only go by my personal experience.

Bill
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