hosam

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HELP… folks, I have a GP Pitts that is in like new condition and a DA50 and want to combine them and have a punch of questions. The guy I got it from used a Brison 3.2 which was no problem for him as the carb is on the side. It appears that I may need to drill a big hole in the motor box to clear the carb, which will put the carb inside the motor box, does this have any effect on the air flow to the carb. Also, it looks like I need to use different standoffs then the ones that come with the DA50, where do I get shorter standoffs and any one with a Pitts and a DA know what length to get? Any one got pictures of a DA50 on the GP Pitts. Any help would be greatly appreciated… Hosam

Tired Old Man

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Placing the carb inside the motor box actually often improves carb performance at various throttle settings. As for the standoffs, just measure the distance from the motor box face to the front of the cowl to obtain the total distance. Now measure the length of the engine from the back to the face of the propeller hub. Subtract the engine length from the cowl/motor box length and add 3/32 TO 1/8" for spinner backplate clearance and you have the needed length of the standoffs. Wood dowels work just fine for those. It may not be flashy or expensive enough for some doing it that way, tho.

Rcpilot

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I'm just taking my GP 1/3 Pitts outta the box. Power is Fox 3.2 Side carb. Probably going to have to hack a big hole in the side of the cowl.

Tired Old Man

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I had a Brison 3.2 in mine. The designs are similar. A side hole in the cowl was not neccessary with the Brison and probably won't be with the Fox

hosam

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Silversurfer, thanks for the input. I was going to use four Hitec 475 (76 in oz) on the wings and two on the elevator with one Hitec 645 on the rudder. whats your recommendation/setup?

Tired Old Man

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That will work just fine. I'm one that believes a higher performing plane deserves higher performing servos. You will absolutely notice the difference and get spoiled by it. I know that affordability often becomes an issue, but if you can go with a quality , metal geared digital at all primary control points. Throttle's not as much of an issue but the difference will be noticble between analog and digital/coreless.

Thunderbolt47

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I agree with silversurfer on the servos. there is a world of difference in the 645 and the 5645. In my mustang with the 645 it would not stay on track. After checking the linkages. I put my degree meter on the control surface and there was a 2 to 3 degs difference in up and down. (Out of 5 servos only two centered right.)The 5645 where dead on every time.

Rc pilot here's a pic of mine with a fpe 3.2. basicly the same as the fox or brison.

EDIT: sorry wrong picture. I'll look for it though. I think the pic I'm looking for is on Film paper so I'll have to scan it.

Tired Old Man

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I forgot to add the the slave strut installation for the ailerons noted on the G/P website works out very well. It saves weight, money, and wiring. The tradeoff is a little extra work in assembly and dissasembly at the flying field. About an extra 8 minutes each end.

Thunderbolt47

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Here it is. Not to much hacking. The scoop thing on the bottom had to be removed.

Rcpilot

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Nice. Thanks for the pic of the FPE. My local flying buddy has the Pitts too, and he's using an FPE 3.2 I saw it last night, and you are correct. The FPE 3.2 and the Fox 3.2 engines look almost identical.

I'm using JR4721 servos on mine. 4 aileron--2 elevator--1 rudder. All 4721 coreless servos. 120oz torque should get the job done.

Tired Old Man

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The 4721's are nice servos. Pretty quick.

Rcpilot

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I have never lost an airplane to a mechanical failure.

I am guilty of putting too much servo in most of my airplanes, but I never strip gears or experience blow-back.

I see plenty of guys trying to get by with the minimum or even less than recommended. Doesn't usually work very well for very long.[sm=lol.gif]

I usually look at the what the manufacturer specs for the max servo size and then increase my torque output by 50% as a minimum rule of thumb.[sm=thumbup.gif].

rpmrpm

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See if those pics help! Just a note, GP made 2 different sized firewalls, so do not use others measurements or stand off sizes. This one i build for somebody used the stock2.5in stand off's. PS; get the tall landing gear!!!!!! from TNT.

Tired Old Man

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Bless your heart. I went through a lot of props before the idea of longer gear legs came to me. Then the call was made to TnT with the measurements and the rest is history. Glad to hear that someone else likes them, too.

hosam

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thanks for the pictures rpm. I think my Pitts has the same motor box but I am going to mount the engine with the standard 2.5" and make some measurements. If I need to go shorter a freind of mine has a machine shop that I can whip out the size I need in no time... by the way, did you renforce the motor box in any way? and what servos do you have on the airplane?

got a web site for TnT gears?

Hosam

rpmrpm

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Servos? hs945mg on elevators and rudder, 4 jr ds811 in wings and 2 hs225mg for throttle and choke. Remember the tall landing gear not only gives you nice prop clearance but makes the GP pitts easier to land and take off.[link]http://www.tntlandinggear.com/store/shop/Product_List_Gear.htm[/link]
I only pinned the firewall and epoxy coated inside and out.
found another pic.

Thunderbolt47

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Hey Guys, I had problems landing my Pitt also. It would just bounce, bounce, bounce. When I moved some weight forward it landed like a trianer. I could wheel land it or 3 point it. The only time I ever broke a prop was during the many bounces and ending with a flip. I though for a while there I was going to have to sell it to the ZOO.

hosam

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rpmrpm & Silversurfer, thanks for all the help. Here is what I have done so far and need some detailed information on other setups. Servos for the wings and tail are done. The engine mounting holes are drilled and I am using the 2.5” stand offs, which came with the motor but I have a friend machine me a 2” set. Pinned and epoxies the motor box. Made a hatch opening in front of the landing gear under the fuel tank. Now for the questions…

1. If I use the 2.5” stand offs, the DA50 carb will be about ¼” from the motor box, how big of a hole do I need to make in the motor box? rpm, your pictures shows big hole, how big is that?
2. If I the 2” stand offs are used I will have to make a whole bigger then the carb, about 2” in diameter. Will that weaken the motor box?
3. Balancing the plane, with the DA50 on the nose should I use the 2” or 2.5” stand offs? I read that this plane is nose heavy with the DA50, figuring I should move the engine back as far as I can.
4. Where do I install (how far back) the throttle & choke servos, Rx battery and Rx?
5. I read somewhere that the CG of this plane is not correct in the manual. The instructions indicate that the CG should be between 5” to 5.75” from the leading edge of the top wing. Where is the best locatin for the CG of this plane? Close to the 5” mark or further back or forward of the 5” mark?

Hosam

rpmrpm

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I do not remember the size of the hole, pic a hole saw about the size of the carb. I used the 5.5CG and we will be moving it back. This one was built with a smoke system w/ all of its component, pump, tank, battery all over the cg. Servos, I built a rail at leading edge of cockpit floor for 2 hitec 225's the Rx battery also mounted in this location. (sorry do not have any pics of interior)

Tired Old Man

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I used a Brison 3.2 in mine, and for ease of mounting I stuchthe throttle servo ( a mini) on the side of the engine box. The hole in the center of the mounting wall is not really important. The area from the engine bolt mounting holes to the outside edge of the mounting wall is where your strength will come from. Use the size standoffs that will let the engine sit in the right location for the prop hub to just clear the front of the cowl. 1/16 to 1/8" clear is good.

Use 6 inches for the starting C/G, and make plans to go a little aft from there after you see how yours suits you. The plane comes out nose heavy with any size gasser from 40cc's up. Plan for an aft battery installation. It was not originally designed for gas engines, but gassers ended up a favorite for power plants.

z24nemesis

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Anyone with a set of busted up set of wings willing to part with?

b-mccor8

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just like posting my pic. I slaved the ailerons, fuji 50 stock gear front and back about 100 flights