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Great Planes .40 P51 kit build...

Old 04-07-2005, 07:39 PM
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270win
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Default Great Planes .40 P51 kit build...

I'm just 3 months back in the hobby from a 10 year break....
I started this kit about 2 months ago but got distracted with assembling and flying some planes I'd be more comfortable with.
Ugly stick .40
.60 Cub
.40 Extra 300

Anyway, now I'm back at the building table. I've already built the horizontal and vertical stabs as well as the elevator and rudder. I've also built the right wing and have the top of it sheeted. It's time for the retracts (Dave Brown mechanicals) which I've ordered from my LHS. I'll get some pictures posted and start on the left wing in the next couple of days... I had one of these back before I quit the hobby. It's a relatively easy build and a GREAT flying model.

I'll post the step by step if there's an interest....

270win
Old 04-07-2005, 09:13 PM
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Fubar-One
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Default RE: Great Planes .40 P51 kit build...

"Expresses great interest"
[8D]
Old 04-08-2005, 12:22 PM
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Default RE: Great Planes .40 P51 kit build...

270win,

"Good to go" on the continuation of your P-51 build.

I am also in the middle of this kit but have applied new techniques to this one. I built up the tail section (rudder, elevator and stabs) rather than use the 'slabs' provided in the kit. I am also using Dave Brown retracts with Robart 652 RoboStruts and 2-3/4" wheels for our grass field, retract tailwheel and all hidden control surface actuators (Beckman Concealed Actuators).

I'll power this one with a new Saito FA-80a 4-cycle engine and digital servos. I like the idea of programming the retract servo to scale speed, too!!

Don Smith
'see us on the web'
Flying Electrons
http://flyingelectrons.com/navigate.htm

vtwin@wi.rr.com
Old 04-08-2005, 12:58 PM
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biton
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Default RE: Great Planes .40 P51 kit build...

Hey,

I'm also in the process of assembling this kit.
I chose the GP retracts with 2-1/2" wheels ( I believe the wing is to small to accomodate any larger wheel).
Haven't decided on an engine yet.
Biton
Old 04-08-2005, 03:51 PM
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Default RE: Great Planes .40 P51 kit build...

I am in the process of finishing this model and am also just getting back into the hobby after a 10 year break. The P51 took me all winter since I am gradually breaking the wife in with the amount of time I could really spend down in my Shop. Next winters project will come together quicker.

My P51 will be powered by a OS 46AX and also has the Dave Brown mechanical retracts. I am finishing it in a Tuskegee Airmen scheme. The Duchess Arlene to be exact. Can't wait to get it finished up and in the air.

I'm interested in hearing your build progress.

Brady
Old 04-08-2005, 10:19 PM
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270win
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Default RE: Great Planes .40 P51 kit build...

I can't find my digital camera!!! I finished as much of the right wing as I could today without the retracts on hand I went ahead and filled and sanded it. I started to build the fuse too. I thought about a retract tail wheel but decided that since it's not scale I'd wait till the next project to go all out. I used to be a scale freak when I was into the hobby earlier...... I think I may be returning to those same tendencies.....

The thing I like about this plane is that it flys so good and still has a good profile in the air. I'll post some pix as soon as I find that camera.

Will those Robostruts work with the smaller wheels too? Or are you just upgrading the tire size due to flying off of grass?

270win
Old 04-09-2005, 07:15 AM
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Default RE: Great Planes .40 P51 kit build...

I chose the 2-3/4" wheel as they are closer to the scale size. Althought the RoboStruts do not extend out as much as the real struts do on take off, they will retract 'shorter' up into the wing. I chose to install them in the place the plan calls for which is further outboard and back than true scale, about where the .50 Cal guns woulld be placed in the wing. This will provide for proper front mating of the wing into the fuse. The landing gear is also not designed to go as far forward as the real gear either. Trade offs are abundant in this scale! My plan is to also install inner doors with mechanical open-close mechanism.

Here are a couple images of the gear in place and beginning fitting of the aileron with the Beckman Concealed Actuator. I am actually going to use Robart 3/32" hingepoints here instead of the 1/8" shown as they are too large for this size wood aileron.

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Old 04-09-2005, 11:13 PM
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270win
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Default RE: Great Planes .40 P51 kit build...

I got the lower fuse formed up complete with scoop and sheeted all. I installed the firewall with 30 min. epoxy before leaving the shop. I'll get the left wing built Monday and then I'm prety much stuck until the retracts get here....

Maybe they'll show up on Monday or Tuesday.

Any of you built any of the Top Flight warbirds?

How does this kit compare?

I know there's more to the FT kits but how much more difficult would you say they are?

270win
Old 04-10-2005, 12:07 AM
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Default RE: Great Planes .40 P51 kit build...

I had a set of Dave Brown retracts from a 'former' airplane that met up with the earth at high speed (real pilots NEVER throttle back, you know...LOL) but had a new set I recently purchased but the side plates were not bent correcty. In fact they were far from 90°. I complained directly to Dave and they sent me out two new sets of side plates.
I still had to bend them to sort of match the contour of the wing and glue in the two mount rails seperately to match the bend.

The heck with it, Sunday is FLYING day!!!


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Old 04-10-2005, 01:21 PM
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270win
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Default RE: Great Planes .40 P51 kit build...

I don't get to work on planes on the weekend, just Monday through Friday. I build in my shop every chance I get. This should be a good week to get lots of building done. Maybe even all of the build up. I'm still looking for that digital camera...

270win
Old 04-10-2005, 09:30 PM
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Daryl_y
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Default RE: Great Planes .40 P51 kit build...

I also just bought one of these kits wasn't really looking for it but it was at the LHS and selling for a few buck less than what it was at Tower, I couldn't resist . Been having to work a lot of forced overtime at work so I likely won't get to start on it for a while. It is for sure going to be built with retracts and depending on how much money I want to spend I will power it with a ST 50 or a 70 4-stroke. Great Planes has taken some lumps from some people RCU but I most say the wood ,plans, die cutting and hardware all look really good except for that damned adjustable engine mount .
Old 04-10-2005, 09:45 PM
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270win
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Default RE: Great Planes .40 P51 kit build...

Yea, the adjustable engine mount is not the greatest idea to come from GP. I always replace them with the Dave Brown mounts. This is a really easy kit to build and when it's finished it really flies great.

270
Old 04-11-2005, 06:25 PM
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Default RE: Great Planes .40 P51 kit build...

Well my LHS is closed on Mondays...[:@] I forgot! I finished everything I can do without my retracts and engine. Once I get them and the retracts are installed I've probably got about two solid building days to be ready to fill and sand for covering. I can't wait to get this thing in the air.

270
Old 04-11-2005, 11:33 PM
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Default RE: Great Planes .40 P51 kit build...

Fragmentum.
Your robart struts look good. I am building this same plane and using Dave brown Mechanical retracts.
One thing I noticed in your picture, is that you have not sheeted the wing top .
I had found the retracts to be pretty big, and even when the top level was flush with the wings, the bottom part nearly touches the wing top sheeting..
So since your retracts are a bit below the surface of the ribs, aren’t they protruding from the other side ?
Specially since you do not have the sheeting..

Let me know your observations on this,
Gaurav
Old 04-12-2005, 06:25 AM
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Default RE: Great Planes .40 P51 kit build...

gauravag,

I have not sheeted yet as I am still working on the mechanics in the wing. Working on the hidden aileron controls right now with the Beckman Hidden Actuators. Then I will build the flaps and controls for them. I intend to fully sheet both sides with contest grade, light weight balsa.

Here are a couple shots of the retract setup. I will trim a little off the top edge of the retract to get better sheeting clearance on the top of the wing. I will want to be able to remove the retracts after the plane is done for cleaning and lubrication from time-to-time, so they may be 'open' when completed. I may countersink the mount plats and use counter sunk screws as well.

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Old 04-12-2005, 09:41 AM
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biton
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Default RE: Great Planes .40 P51 kit build...

Hey people,

I need some advice on engine alternatives for this kit.
I really doubt a 46 engine will be enough to power this kit (my building tends to turn up on the heavy side - I like to build strong) so I think a 50 or 60 size will be a better choice.
Right now, my sights are zeroed on the Super Tigre 61 installed sideways with a Pitts muffler.
Would really like to hear comments on the engine size, weight issue and sideways installation (is inverted installation a better idea for a 2 cycle ?).
Thanks,
Biton
Old 04-12-2005, 11:02 AM
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Default RE: Great Planes .40 P51 kit build...

Biton,

In MY humble opinion, I think a 60 size would be good for this model, especially is you build on the heavy side as you say. I prefer 4-cycle engines as a whole and that is why I am installing a Saito 82 in mine. I also would like to use a 3 or 4 blade propellor for scale appearance as well.

As far as engine mounting is concerned, I have not mounted a 2-cycle engine sideways or inverted before but I have read several posts in the past that inverted 2-cycle engines do not operate well that way, but sideways mounting is OK. 4-cycle engines work equally as well in any position. I want to use inverted mounting with exhaust exiting down out of the cowl and not break up the nice lines on the side of the plane.

Weight to power ratios should also be considered.[:@]

The OS 61FX weighs 672 g, or 23.6 oz and produces 1.9 hp at 16,000 rpm

The Saito FA-82a weighs 462 g, or 16.23 oz and lighter than the FA-65, FA-72 and the FA-80! It produces 1.5 hp at approximately 8500-9500 rpm

The 4-cycle will swing a larger diameter prop at a lower rpm and I think this is better for scale. If I could mount a reduction drive and a 4 blade prop in this warbird, I would do that, but this scale is not supported by other manufactures for such devices, and I do not have a machine shop.
I know Byron Originals once had a reduction drive for a 60 size engine for only one of there models, a Spitfire if I am not mistaken. That would be neat to install in this model as well. I have pictures of this Byrodrive and would like to build one for myself someday.
Old 04-12-2005, 01:03 PM
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Default RE: Great Planes .40 P51 kit build...

I owned to of these models. Both had OS .45 engines in them and were plenty of power. The second one had spring air retracts and flew just fine on the .45. Because of the size and area of the firewall, you will be hard pressed to fit a .60 on the nose of this bird.
Old 04-12-2005, 03:34 PM
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Default RE: Great Planes .40 P51 kit build...

One thing to be aware of, this plane can't handle too much extra weight. I made the mistake of using an old Saito FA 80 on mine, and once I added enough tail weight to balance it, the wing loading was so high I could never get it to make a decent landing without bouncing all over the place.
Old 04-12-2005, 05:00 PM
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Default RE: Great Planes .40 P51 kit build...

By comparison, image weight specifications are as follows:

OS 46FX weighs 489g or 17.2oz with muffler

Saito FA-80 weighs 540g or 18.97oz

Saito FA-82 weighs 462g, or 16.23 oz, lighter than the above two examples

I am also going to install and use flaps that should have a great effect on landing speeds.

What do you think?
Old 04-12-2005, 05:48 PM
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Default RE: Great Planes .40 P51 kit build...

Mine is still unopend in the box. The boss man has me working slave hours. Which gives me plenty of money to spend on the hobby but no time at all to build (or fly for that matter). Although I am satrting to get the gear together for it. I was originally going to put a Super Tigre 50 in it but I might spring for either a OS .70 or Saito .72.
Old 04-12-2005, 08:06 PM
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270win
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Default RE: Great Planes .40 P51 kit build...

I build them strong too because I fly them hard. The one I had was built this way and I used an OS46SF with the pitts muffler. It had plenty of power and was a good flying plane too. With a big 4 stroke up front you may run into some prop clearance issues, especially on turf runways. This plane is basically an ultra sport with mustang trim. The more weight, the worse it'll fly. Besides, the much larger engine will just stick out that much more than the smaller engine.... But, that's why we have options...

Anyway, I got the retracts today... I changed my mind and bought the GP mechanicals. They don't look bad either. I got the retract rails installed today and cut some of the ribs to allow the gear to cycle smoothly. What are y'all using for the wheel wells? The manual says a styrofoam cup or balsa.... I'm thinking a plastic lid to a spray paint can. I think that's what I used before.

270
Old 04-13-2005, 11:11 AM
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Default RE: Great Planes .40 P51 kit build...

I will be building as scale of wheel wells as I can as I am also installing inner gear doors. I believe when I am finished it will still be very light weight but much more scale in appearance (OK, blame Dave Platt for this thinking!!! LOL).

I ordered up some 'contest grade' balsa for construction and sheeting, and this should save a lot of weight in the construction from here on out.

I have been working on the hidden Beckman actuator installation for the ailerons and here is an image. I am also using Robart hinge point pockets to facilitate removal of the ailerons for finishing, painting and maintenance.

The color shaded area is where a screw on hatch will be to get access to the workings of the Beckman hidden actuators. Sheeting will be all around this 3/32" hatch with 'contest grade' sheeting to save weight.

Access hatch installed...

Next part of the project is to construct the flaps....
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Old 04-13-2005, 04:28 PM
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Default RE: Great Planes .40 P51 kit build...

Hey Guys,

Do you think a 60 size engine will pose a balancing issue ? The reason I am skeptical a 46 engine will be enough is the large wing area and (at least in my case) their considrable weight. I do agree the 60 size engine will stick out quite significantly.
Does anyone have any experience flying this kit with a 50 Webra sport engine ?

270win - I also use the GP mechanicals. For me it was either these or the Hobbico retracts, so I picked the GP ones and they do look nice. I wander how they will hold on our grassy field.
Biton
Old 04-13-2005, 09:37 PM
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270win
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Default RE: Great Planes .40 P51 kit build...

I think it just depends on how rough the grass is at your field. The one I had was flown off of a paved runway. Once I had them adjusted I flew the plane for 3 years and never had to touch the retracts. Good luck deciding on an engine.

270

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