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Sport JTEC RADIOWAVE 26% Pitts Model 12

Wacobipe

100cc
The only thing he has to turn the scoop around to get the hot air out.??????????

My scoop is open, and telemetry tells me I'm fine (Jeti is AWESOME....you must shroud engine on this plane or air flow around the engine...not through it as there is so much free area inside the cowl). I think you should plug the scoop so air does not flow into it...as that air intake is useless for our needs. I'd open the scoop, screen it, and then plug it behind the screen so it looks scale.
 

stangflyer

I like 'em "BIG"!
And yet, another unexpected set back. The winter weather in Idaho has been atrocious today so much like school students, we at work got a "snow" and "extremely hazardous road condition" day. Which although I would have preferred to work, I felt a little elated that I could spend the day working on the last remaining items on the Pitts. I got the final sanding on the fuse done and man am I glad that is out of the way. I decided I would get the cowl ring set in the cowl and the cowl mounted so that I could next get the 3w 70 twin mounted. I started by measuring out the exact center of the cowl face and marked it for reference. Then using my drill, I started the prop shaft hole and finished up with my dremel with a sanding drum. To enlarge the hole, I used the prop washer as a rough size ring. Then opened the hole up a little more. After that, I opened up just what should be needed for air to pass by the cylinders. I was surprised to discover how deep inside the cowl the 70 sits. I will have to really baffle those jugs.

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I figured since I was cutting holes in the cowl, I might just as well get the air scoop opened up. So starting with the larger sanding drum, I opened up just to the edges of the scoop. Changed out to the smaller drum to get into the corners a little better. It will still need just a little sanding to clean up the edges, but hey...looks pretty cool.

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I had to snap another photo of the fuse as I was thinking to myself...dang, this thing is just "screaming" for some kind of covering. Mostly of the Orange persuasion. What do you all think?

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I'm actually seriously contemplating a two toned covering....(to start with). Which will mean very minimal double layers. Which should help in the weight department. My thought is this.... front portion of the fuse being the same Orange as what is on the H9 Sukhoi. At or somewhere near the first to middle of the cabane struts, the orange will "flame" transition to Pearl Purple. From there, it will be purple to the trailing edge of the rudder. Of course I will break it up with some accent colors, (how I do not know yet) of Black and or Silver. Of course my covering of choice is Ultracote. White may be out the door for now. This is just a thought on the covering. How about some input guys? Can you envision my description? What do you think?

Ah yeah so you're all wondering about the previously mentioned set back, right? To me it kind of sucks because this plane is just "soooo" close to being ready to cover. Seems like there has been one issue or another to deal with throughout the entire build. I am talking about the naturally built in "EXTREME" up thrust on the firewall. It would be almost impossible to "accidentally" build in up thrust as the firewall is keyed into the fuse sides and thus, the thrust is automatically set.

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@Wacobipe and @Maxwell1945, can you give me some input please? Did either of your planes have this much "UP" thrust in your firewall? I realize all I will need to do is add spacers to the top of the engine mount, (or an extra length to the custom standoffs I use) but really was not wanting to "cobble" together "anything" on this plane. I have one last little chore to complete before proceeding with my covering. That is the landing gear cover. Although it won't take any time at all to design and build it, I am a little discouraged at the moment and really don't feel up to doing much with it for a bit. We'll see how it goes the rest of the week.

Anyone got a match or a lighter????
 
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stangflyer

I like 'em "BIG"!
My scoop is open, and telemetry tells me I'm fine (Jeti is AWESOME....you must shroud engine on this plane or air flow around the engine...not through it as there is so much free area inside the cowl). I think you should plug the scoop so air does not flow into it...as that air intake is useless for our needs. I'd open the scoop, screen it, and then plug it behind the screen so it looks scale.
And no doubt I think you are correct. I looked at the construction of the fuse again. I would be "damning" off a ton of cutouts to keep the air out of the fuse and have it directed down the tunnel.
 
Hi Rob;
First off my firewall was straight and had no up thrust in it , but I had to make a motor mount because the two lower engine mounting holes were centered in the bottom of the motor box plywood . You may look at the cowl pictures of mine , I had to remove the scoop on the bottom to clear the muffler down pipes, also I put two louvers on the bottom sides of the cowl . The ones from TailDrager Rc are the best ones . Hope this helps !!

Van
 

stangflyer

I like 'em "BIG"!
Hi Rob;
First off my firewall was straight and had no up thrust in it , but I had to make a motor mount because the two lower engine mounting holes were centered in the bottom of the motor box plywood . You may look at the cowl pictures of mine , I had to remove the scoop on the bottom to clear the muffler down pipes, also I put two louvers on the bottom sides of the cowl . The ones from TailDrager Rc are the best ones . Hope this helps !!

Van
So real quick question.... Will setting the thrust to "zero" be correct for this plane? Is there a difference of thrust on bipes vs. monoplanes? When you say your firewall was straight, I am assuming the up thrust is set at "zero"? Sorry, this is three questions. Just trying to get this thing ironed out before I proceed. "IF" I even proceed.

I am just really burnt out on it.
 

jtec/radiowave

70cc twin V2
Rob,

The thrust should be built in. you should have some right and a little up. Your going to want some right thrust. I have never seen a plane that did not require some right thrust. I believe the whole series is designed that way.

Al
 

stangflyer

I like 'em "BIG"!
Rob,

The thrust should be built in. you should have some right and a little up. Your going to want some right thrust. I have never seen a plane that did not require some right thrust. I believe the whole series is designed that way.

Al
I understand and fully agree with the "right" thrust. I am fully aware of that. However rough guess on "up" thrust is around 2 degrees or more. I will put my digital meter on it this evening for a more precise measurement. I was not aware of the need for so much "up" thrust on any plane.
 

jtec/radiowave

70cc twin V2
Yep, you are correct. All the pitts have 2 degrees up thrust in them. I verified both on the fuse we have here and the AutoCAD files to confirm. It is not easy to see until you mount a motor but if you look closely at the tabs for the firewall you will see a couple of mm difference between the three tabs.

We do run a bit of up thrust in the MX and the Extra's as well but with the bipes you do run a bit more to reduce the mixing.

Kevin
 

stangflyer

I like 'em "BIG"!
Yep, you are correct. All the pitts have 2 degrees up thrust in them. I verified both on the fuse we have here and the AutoCAD files to confirm. It is not easy to see until you mount a motor but if you look closely at the tabs for the firewall you will see a couple of mm difference between the three tabs.

We do run a bit of up thrust in the MX and the Extra's as well but with the bipes you do run a bit more to reduce the mixing.

Kevin
Good enough. Thank you Kevin for taking the time and making the effort to confirm this. Guess I just never realized the requirement of the up thrust in the bipes. I will still measure the firewall just to be sure I didn't somehow "botch" this build.
 
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