RE: PassTime Perigee Build thread
 

Yes, that is interesting. And, I can see how that diagonal grain could twist the wing.

Your cradle idea sounds like it will work fine. But, here's how I would do it:

For the LE I would use a piece of balsa about 2" wide x 3/16" thick, draw a centerline lengthwise on it and line up the centerlines of the ribs with that line. Do the same for the TE. Then, the wing will be suspended above the board on LE and TE which you can pin down. I call this the "lost jig" method because after you remove the wing from the board you saw off the extra pieces of the LE and TE.

Here's an old drawing I did a while back.

David

RE: PassTime Perigee Build thread
 

Hi Nic,
Of course we are interested. One really good way is to make "lost foam" wing cradles. You can even sheet the panels with white glue or poly and weight up the cradles like a foam wing. That ends up making things straight.

Dean

RE: PassTime Perigee Build thread
 

Dave & Dean,

both are really good ideas. Let me think on this.

I like the lost jig.
Foam cradle would be great, but alas, no foam nor way of cutting it.

RE: PassTime Perigee Build thread
 

OK, here's the left wing panel, all the top sheeting and cap strips in place. Still have to sand down the LE and TE to final dimensions, so they are looking rough yet.

RE: PassTime Perigee Build thread
 

And now the bottom view of the center. The two ply pieces are clearly visible, I intend to put a shear piece between them as I mentioned so the LE dowels will have something to glue to at their rear end.

Next, build the jig to sheet the bottom. Maybe by the end of this week?

I have been following BobHH's prototype Perigee kit build with interest.

RE: PassTime Perigee Build thread
 

Really nice work, Nick. What a sexy wing for a plane of its date. The Perigee must have really turned heads when Brett first flew it.

I really like these early/mid '60s pattern planes. I have been thinking of building deBolt's Interceptor for a while, which was from a couple of years later, I guess.

David

RE: PassTime Perigee Build thread
 

Since the wing is progressing, I have to look at the aileron servo arrangement. I want to use mini-servos out on the wings. I would like to put them between the last two ply ribs, but then the pushrod will overlap the landing gear. Although I don't think this is would create a problem, what do you guys think? Closer in means less moment of inertia on the roll axis, but I think it is such a small difference that you will not notice it in real life.

The use of ply ribs on each side of the servo is very obviously a strength issue.

Discuss.

RE: PassTime Perigee Build thread
 

You won't need ply ribs to mount the servos, so long as the spars are not compromised then you could even mount them on a plate glued to the spar web and one rib. I mean, the servo is only moving one aileron, the biggest force on it will be a bit of 'G' on a hard landing.
Evan.

RE: PassTime Perigee Build thread
 

Good point. I'll run across 2 ribs like an extended cap strip, then reinforce from inside for servo mounting.

RE: PassTime Perigee Build thread
 

Call Bob Hunt
(610) 746-0106 lost foam jigs, built wings and everything!

Dean

RE: PassTime Perigee Build thread
 

It's amazing how doing this build thread keeps me motivated. I can't stay away, knowing I should keep posting progress.
Here's the next step. I put the ply block in between the ply bracing, so the wing dowel will have a rear purchase. Also note the holes drilled for servo wiring out to the wings.

RE: PassTime Perigee Build thread
 

Next step is to make the jigs to hold the wing upside down and level. I decided to take the quick & dirty method. I put each wing rib from the other side on the upper edge of a 1/4 x 2 x 36 piece of balsa, leveled the centers at the LE and TE then traced it. Remember, you have to do this upside down, since the top of the wing is sheeted, and we want the bottom to be face-up. I got three ribs out of it, then used the remainder of the piece to make some "feet" to make it easier to keep them level and upright.

RE: PassTime Perigee Build thread
 

OK, now the moment of truth..................

Put the wing, upside down, on the jigs, and what do I see, WOW, a huge amount of wash-in at the tip. Just look at that! I am convinced this is why some people have had problems with Perigees in the past. By weighting the wing against the jigs while I sheet the bottom, it will be true, and I am sure my Perigee will land like a *****cat.


Purrrrrrrrrrrrrr

RE: PassTime Perigee Build thread
 

WOW! That's quite a twist! I think that I would over compensate just a hair though on the jig. Wood has a way of "bouncing" back some. Just my .02. Looking good though Nic!

FB

RE: PassTime Perigee Build thread
 

I thought about that, but I think I will just build it straight. Remember, the wing was straight when I sheeted the top, so any bounce back will also show up on the bottom sheeting, hopefully in an equal and opposite way. If it measures out to not be true, I hope I can impart enough corrective twist when I cover it.

I have decided to use yellow super coverite on the wings, and white regular coverite for the rest. Strong, light, fuelproof, takes primer well.

RE: PassTime Perigee Build thread
 

Another day, another update. (Can't promise that all the time)

Here's the wing, jigs pinned down, wing pinned to the jigs, and applying the bottom sheeting. Actually, this shows the use of a french curve to cut the taper in the sheeting. Altogether, it takes 5 major pieces of 4" wide balsa to do the wing. Plus one more scrap for the last bit at the tip (like a cap strip, but he uses that weird sheet grain)

RE: PassTime Perigee Build thread
 

Quick update. I got up this morning, first thing I did was to pull the T-pins and check, It's STRAIGHT! WooHoo.
Now for capstrips, some touch-up sanding, and time to start the right panel.

RE: PassTime Perigee Build thread
 

Nice going Nic! Save those jigs for my build!

RE: PassTime Perigee Build thread
 

Sure, Rick. Not a problem.

Photos to follow at 11.00

RE: PassTime Perigee Build thread
 

OK, spent a little time today on it. Here's the bottom of the wing, sheeted, cap stripped, and servo bay installed. Close-up shows that the servo will be recessed into the wing. Hats off to Tom Brett, who engineered the heII out of this plane. (no dis-respect intended. He did a great job)

RE: PassTime Perigee Build thread
 

Now for the reason why the servo is recessed. It makes the top of the servo flush with the wing surface, reducing drag. Second shot shows the servo mounting from the top side of the wing. Now I have to remember to put a string through the rib holes to run the wiring after it is finished.

RE: PassTime Perigee Build thread
 

Can't...............Stop......................Buil ding..........................

Getting ready to start wing panel #2.

Also, have decided to not use the maple beam mounts, etc. and go with a more modern glass-filled mount, Du-Bro Nosewheel, etc. Here's the new firewall of 1/4 ply, instead of the kit 1/4 balsa.

RE: PassTime Perigee Build thread
 

Thought about tilting the firewall to get the downthrust / right thrust built in.

However, it is a difficult measurement. And, especially for the downthrust, it will tilt the nosewheel backwards. So I'm doing the firewall straight, and putting washers for right thrust, then on the mounting lugs washers for downthrust. Easier to adjust as needed, too.

RE: PassTime Perigee Build thread
 

Gotta keep building...........

OK, so now the right wing has all the top sheeting in place. Lots of clothes pins to keep the sheeting wrapped down to the LE strips. Actually, it is getting easier to cut the sheeting, since I know how it will configure.

I haven't measured the dihedral, I am relying of the wing spars to be accurate. We'll see when it's finished.

RE: PassTime Perigee Build thread
 

OOPS!

Gotta remember to put a string thru the wing for the servo leads before it is totally buttoned up!