Tony, do you have any pictures of the tank mod? Would a 12 or 14 oz tank get it even lower as it would be smaller? I could live with an 8 or 10 minute flight as right now my flights are 2 minutes and pucker up on the dead stick landing. About 8 flights on this now two different days out and 8 dead sticks. I have been real frustrated with this model, I get it running good on the ground and fly for 2 minutes and dead stick constantly. All my other Evo and Os planes I can tune so I almost never have a dead stick. I am using the remote needle valve on the Evo 60 also, would you recommend bypassing that and moving it up to the carb? I pulled the engine out and ran on a test stand, ran perfect, but wont run in the plane.

Dang tempting Tim! I'm going down the airport after work today to try and finish up the condition inspection and then sign it off. Any other events this summer (?) asI can certainly get down there.

hQQk

And a good point 8178 (I'm not an an aero engineer but do have an aero degree) as the gear are part of the parsasitic drag problem.That problem is that as speed increases the parastic draginfluence does too; that is the parasite drag curve rises as speed increases. Your example is good one too, or you can simply hold your hand out the window to get a feel for it. Now if you hold your hand palmflat and parallel to the windstream you'll notice little force on it, as you increase that angle you'll feel the force pushing your flat palm back (but maintain the position with arm muscle), it gives you an idea of the lifting forces a wing generates.That's oversimplified but a good example for the unitiated. Now start hanging stuff off of that palm (wing) and you can begin to see how it interferes with the wings ability to use the lift generated, that's intereference drag (one type of of parasitic drag). So ultimately retracting the gear likely is beneficial, but just how much is open to measurement because the mechanics of retracting the gear do increase weight, leave open bays etc.

hook

Ed,

Could you detail how you did the above and perhaps add some pics to the thread? One of my LG mounts is loose and needs to be fixed before flying it again. I'm sure that this will happen to others as well. Thanks Ed!

FB

Hey FB,

I hope these help a little. You can see some bracing behind the 1/64 ply cap. The original hole for the Robart LG loop was filled and cut to fit the E-Flight loop. The ply blocks go back into the wing to tie thing together.
I miss my old 35mm camera for close up photos.

Here are some better shots of my LG mounts.
Crankpin gave me some good ideas on how to shoot close-ups. THANKS CRANK

Thanks Ed!

FB

I had the opportunity to watch this design perform, as there were several P-7 ARF's in attendance at the Classic Pattern Get-Together this past weekend. This thing is a winner. Watching Tony F put it through it's paces was like going back in time, and showed that it is everything that it was back "then". Seeing it go through eight-pointers, long slow rolls, reverse point rolls, figure "M"s etc was very inspiring. It is also quite durable as well. There was a couple of off runway dead-stick landings, as well as one that snap rolled onto it's back onto the asphalt on landing. Damage in each case was limited to scrapes and bruises. (Your mileage may vary).

It is my observation, based upon forum traffic, as well as my personal observations and experience that for those of you who are considering one of the Chinese engines (I am not pointing out any particular brand) that you consider first disassemble the engine, remove and discard the bearings, and replace them with quality bearings such as from Boca Bearings. The bearings that come installed inside of these engines are not up to the job. Even with the cost of the replacement bearings factored in, these engines are very powerful, and are a good value for the buck. Be prepared for people coming up and asking "What do you have in the nose of that airplane?".

I have also changed my mind, and ordered a set of Spring-Air retracts for my P-7. I have had perfect performance from them in my Vertigo II. The are super high quality, and made right here in the USA.

Gear up!!

KLX,

Which Spring-Air unts are correct for the P7?

Thanks,
Jim

We usually use Spring Air 202 HD's.

here are some pics of the mods i made to make dubro tank sit level, along with the surgical carbide burr i use to reach the areas modded

Tim,

a little off topic but I was wondering if there is any difference between the E-Flite medium (25-45) and large (45-90) electric retracts other than the strut size. How about dimensions & weight?

A simple CAD drawing of these units would be very helpful in the planning stage of things - any chance you might have one we can use?

TIA, David.

12.4 oz with uncut struts for the 60 size e-flite retracts

I bought the 302's, on the basis that the lower profile may be helpful in the nose area (not protrude into the tank area. )

I would be a little concerned about how much wood you removed from the aft bulkhead that hold the mounting rails for the nose gear. Any shock on the nose wheel might make it break out.

High Tank Problem

OK, back to the P-7. After examining the fuselage, and spending a couple of hours (and a few beers) in contemplation, I have reduced my options to two choices:

1. Go with Tony F's solution. I bought a Du-Bro 16 oz. tank, and it does fit up in the nose much better than the tank that is provided with the aircraft. Examine the attached pics, there is a 1/2" difference in the mid-line of the two tanks. That is significant. The bottom of the tank is the datum. (Because that is where it rests in the fuselage).

Using this tank, it appears to be possible to get the centerline of the tank within approximately 1/2 " of the engine C/L. Not ideal, but in the ballpark.

2. Go for the upright engine installation. This would be a sure bet to establish the correct geometry. Major engineering project, which flies in the face of the "keep is stupid, simple" philosophy. I would like to avoid this scenario if possible. But if that is what it takes, so be it. That is why we call it a "hobby".

Pics: Left= Du-bro tank. Right= H-9 tank.

Hi Robert,
I worked hard to find a tank to line up exactly with the carb on my Tiporare and after using a round section Dubro 12 oz that is within a half inch with the pickup tube in the middle height of the cork, and perfect with it rotated to the bottom, Tony told me that it didn't need to be that close. He says his is almost and inch higher and you saw that it ran like a top. I think you're alright with what you have.
Don't be re-inventing the wheel, that's my motto!
Chris... 

Locally we have two Phoenix 7's flying that are identical in setup. Evo 60, and Jett muffler. We both had the sputtering engine or dieing engine problem in the figure m's when throttling up on the second half with the factory tank. We installed Dubro 16's and the problem has gone away. I do set my engine rich on takeoff and it unloads well in the air.

Chris, Energyman,
I agree with you on this. No science fair project/ Move forward. I have some "Honey- do's" to put in the bag this weekend, then back to the build.

-Robert

Energyman, 1. did you put the Dubro tanks in with the rubber stopper on the bottom of the plane towards the landing gear or on top like a normal installation? 2. Did you drill new holes for the lines out the firewall and 3. did you use the remote needle valve assembly, or eliminate it and move the needle to the carb to simplify?

Hi,

I installed my DuBro tank with the stopper towards the top. It makes no difference which way you do it regards to the engine run. I covered the hole that is in the firewall with some 1/16" ply then drilled new holes for the fuel lines above the motor mount. I did move my needle to the carb as I didn't want to cut that big a hole in the fuselage to clear the rear needle.

Tony Frackowiak

I am breaking from the manual at this point. The first assembly in the manual for the fuselage is to mount the stabilizers. I prefer to do that later with this one. I would rather mount the engine and maybe the nosegear (pending arrival) to minimize hangar rash on the tail surfaces.

The engine mounting pretty much followed that manual. I made a drill jig for drilling and tapping the engine mount. First, I sanded that back of each mount flat, then mounted it on the drill jig. The hole was cut and trimmed for the engine to fit comfortably. The thrust line was checked, and I sanded a hair off of the lower engine mount to take care of some up thrust. I ended up with about a 1/16 spinner gap, with the backplate parallel to the spinner ring on the fuselage.

Thr throttle tube was installed per the manual, and operation manually verified.

Fuel tank:

I cut away the wood at the rear of the nosegear mount, as that wood as well as the front wing mount were holding up the rear of that tank. Bad news. So I removed the offending material with great prejudice, while not weakening the key structures. Now the tank sits level on the top of the nosegear mount. That is as low as she goes, folks. The center of the tank is 3/4" above the centerline of the engine. Not great, but a substantial improvement over the stock set-up.

After the completion of this task, the firewall and all but the immediate nosegear mount was fuelproofed with 30 minute epoxy. Remember fuelproofing?

Per Tony F's Du-Bro tank installation, I covered over the hole in the firewall (1/64 ply) and drilled new holes above the engine mount for the fuel lines.

Nose gear blocks epoxied in place per manual. 30 minute epoxy used here. The manual did not specify the orientation of the blocks. I oriented them such that the nose gear unit would be at the lowest value. I hope that is correct, it aint coming out.

Another picture shows the actual level at which the tanks will sit in the nose. Still way high, but an improvement over the stock tank setup.

Time to glue on the stabilizers. Done per manual. Use lots of epoxy.

Next the rudder and elevator servos and linkages installed per the manual, and dialed in to the specifications given in the manual.

KLX,
Have you trial fit or set the wing in the saddle yet to check wing / stab alignment? Curious because mine was off quite a bit. I had to build the saddle up about 1/16 or so with epoxy/micro to get it aligned with the stab. Also, wing bolt holes were off enough that one aileron nearly touched the side of the fuse, had to open aft two bolt holes to square it all up.Some were thinking they'd try heating then twisting the aft fuse to straighten it. I would think the vertical stab would be off then, at least mine would have been.
hook

And the blue trim on the stab has started to come off *&^%(!