Building the Pocket Peregrine

[irish_lord99]

In the October 2008 issue of Flying Models Magazine there was an article with centerfold plans for a mini thermal catcher called the "Pocket Peregrine." It's a small, simple two-channel glider designed to be launched from what the author calls a mini hi-start (he also details how to make the hi-start). It was designed by one Marc Shimazu-Takahashi, and I've never seen so much plan on so little paper. He managed to fit a 36 inch glider onto one two-page centerfold! The plans are very well drawn and easy to decipher and follow. :)

I took the magazine to a local place and had four copies of the plans made and then I put them in my stack of plans and forgot about them until today. The building bug hit and the only other thing I have going on is a mini vintage type plane that is ready for covering. But I didn't feel like covering, I felt like building!

So away I went. I have to say that I've never gotten this far on a project in one day. Already I've got the pod and tail surfaces ready to cover! Weight so far is 47 grams (with RX and servos but not the battery). The author finished his out at 112 grams, and I'm hoping to get mine done around there.

Specs are:

wing span: 36 inches
Wing area: 157.5 sq. in.
Airfoil: Clark Y
Length: 21.5 inches
Target Weight: 4 ounces
Wing loading at Target Weight: 3.6 oz./sq. ft.

I'm not sure what I'm going to use for a battery yet, though I've gotten ideas about using camera batteries from some guys on the forum and I'm looking into doing that. We'll see. I'll let the pictures detail the build.

~Jake

PS I just realized that I don't have a picture of the finished pod, I'll take one before I cover it.

[Wylie Shaw]

Hi Great Job! Nice little glider. please continue to post your build..


Best Regards,


Wylie Shaw

[brentrob]

Jake,
That table you are building on, is it just a chunk of metal with magnetic piece to place on it? If so, is it home made or did you find that someplace. It looks really slick and I would like to get my hands on something like that.

Thanks,

Brent

[Wylie Shaw]

Jake,
That table you are building on, is it just a chunk of metal with magnetic piece to place on it? If so, is it home made or did you find that someplace. It looks really slick and I would like to get my hands on something like that.

Thanks,

Brent


http://www.airfieldmodels.com/


Wylie Shaw

[blackoutjon]

wow that is tiny if you are able to when you are all finished could u post a vid. of it flying i would really like to see it fly

[irish_lord99]

Brent, the link that Wylie posted is the same website I learned about the magnetic building system from. Frankly, it's awesome! I don't think I'll ever go back to tacks and pins. You can see I also used magnets to frame up the stab. I use them for trusses, control surfaces, anything really. Also, they are great for doing lamination work and the jigs are excellent for aligning wings and tail surfaces.

To build it I used simple 1/4 inch plywood. The cheap stuff that's used for paneling, not the nice birch stuff that he uses on the website. And I bought my latch magnets from here: www.allelectronics.com The block magnets I found locally for really cheap, so I can't tell you where to get those stateside but I'd imagine that there's a website somewhere. :)

So, the stab is currently covered, painted, and epoxied to the boom, I'll post pictures this evening after I attach the fin.

~Jake

[atmosteve]

That is an incredibly cute pocket wood glider, old school and all!
keep the pictures up, looks a real little head turner.
Perhaps a little 1/2 length AAA 4 cell 300mAh NiMH pack would do the job.
Steve.

[irish_lord99]

Well, the control surfaces are close to done. I still have to cover the sub-fin and elevator and attach them, but the hard part is done now. I covered everything with doculam and sprayed on some red acrylic paint with my airbrush. Looks pretty good if I do say so myself. I hinged the rudder with sewn hinges and I'll probably do the same with the elevator.

You can really see how the magnetic jigging comes in handy for exact alignment with the fin and the stab. For the fin I kinda shot myself in the foot though. I used a glue stick to glue a piece of 2mm balsa to the jig so that it could reach over the CF tube to hold the fin square, but I left the balse long enough that it almost touched the CF. Well, as the epoxy oozed out from under the fin I almost wound up with a jig attached to my plane! I was able to hastily correct the mistake without a lot of mess, but next time I'll be sure to leave myself more room!

Well, the next step is to attach the sub fin and elevator, then I'll cover the pod, paint it, and glue the boom into place. If I can stay motivated and undistracted I may be able to finish it up by the end of the weekend.

[irish_lord99]

So I got a bit more done this weekend, but not as much as last. I've got the servos installed, the pod covered and the sub-fin on. I've also finished up painting the pod.

I've decided that I'm going to go with the camera battery option for power, and after putting everything I have on the scale it's come out to 75 grams. That means I've got to keep the wings under 35 grams to hit my target weight. :eek: We'll see how that goes. Part of my problem is that it's impossible to find all the 1/32nd plywood that the plans call for in this country. I'm planning on bringing some back from my next stateside visit, but I wasn't willing to wait that long to start this project.

So we'll see how heavy the wings come out. :) I'm planning on using pull-pull for the rudder, which should save some weight (the plans call for a metal push-pull rod). Unfortunately it's not very feasible to try the same for the elevator.

Cheers,
Jake

[GeeW]

Looking good, I think your colour scheme will help a lot orientating this tiddler :D
35gms for a wing .....no sweat (so long as I dont have to do it!)

Gordon

[irish_lord99]

Thanks Gordon,

Yeah, 35 grams is going to be pushing it. I was hoping to use spruce for the spars, but now I'm not so sure! I recently built a 70cm wing that finished out at 17 grams before covering. Assuming that if I add 25% more span I'll get 25% more weight then in theory I can frame this wing up at under 22 grams. The doculam is pretty light, the real weight comes from painting. I'm planning on finishing the entire plane without painting the wing and then if I'm well enough under my weight threshold I may paint the wing. It would sure be nice for visibilities sake!

Jake

[Mark3]

Any updates?

[irish_lord99]

Well, I've got 3/4 of the ribs cut for the wing and the spars and leading edge cut out. So far I've figured that if I do use the spruce spars then I'm going to be cutting the weight really close... so I'm still debating that in my mind. I may start framing the wing tomorrow or some other time this week and when that starts I'll post some pics.

~Jake

[irish_lord99]

Well, a little more progress made. The wings are 3/4 framed up and I'm pretty sure I'll have the fourth panel done by tomorrow. Now all I've got to do is fine some 1mm balsa to finish sheeting with. I'm out and the last time I checked my balsa supplier was too. :( I'm also hoping to make the wing into a two-piece for easier transportation so I've got to find something to make a dihedral brace out of. Shouldn't be too difficult, I'm hoping to use aluminum. I'd rather use aircraft grade ply, but I've never been able to find it here. Aluminum should work.

So far the wing weighs 24 grams and the final panel should put me at 32, so it looks like I'll make my 35 gram goal after the dihedral brace and paint.

I hope to have this up and flying very soon.

Jake

[cn0rris]

Maybe I missed it, but can you tell me about your boom? From the pictures, it looks like perhaps a carbon arrow shaft?

Chuck

[irish_lord99]

Well, the boom is just a simple piece of 6mm diameter carbon fiber tubing that I picked up at a local hobby shop. There's nothing really unique or special about it I'm afraid. :)

~Jake

[cn0rris]

My local archery range has a bin of used, sometimes slightly damaged carbon arrow shafts. The lighter ones are perfect for small HLG's. I had to choose carefully to get ones that were light enough, but the different arrow models are well documented online, so you can be sure of what you're getting.

They're 4$ each here in San Diego for perfectly good used arrows. Often, damage that makes an arrow unusable to an archer doesn't affect it's use as a boom, so I imagine you could even pick up some boom material for free.

Chuck

[irish_lord99]

Thanks for the pointer chuck. Unfortunately there aren't a lot of archery shops here in Istanbul. I do know of one though, maybe I'll go there and see if he has any junk shafts he'd be willing to part with. The CF tube that I bought from the LHS was only about 6$ USD so not that bad of a price.

Area arrow shafts usually solid or hollow? Oh, and is your name really Chuck Norris? I had a bush pilot friend once named Mike Jackson. Only his mother could call him Michael. :D

~Jake

[scrubs]

Just had to get me to go and look up the issue eh? :-) I printed out some copies too. No wonder I can never FINISH anything.
bill

[irish_lord99]

Just had to get me to go and look up the issue eh? :-) I printed out some copies too. No wonder I can never FINISH anything.
bill

NO KIDDING! As I started working on this project I stopped halfway through another, and in the middle of this one I started planning my next and almost started in on it before giving myself a reality check. Essentially I had to force myself not to start something new and focus on the two projects I've got going plus the THREE unfinished models hanging from my ceiling PLUS the four unfinished plastic scale models scattered throughout the house. :D At least I've got parts for all these projects and I don't need to make any more orders anytime soon. That should appease the budget gods... er, I mean my wife. :D

~Jake (who can't resist starting a good project)

[cn0rris]

Area arrow shafts usually solid or hollow?
Hollow, and if you buy the right models, quite light.

Oh, and is your name really Chuck Norris?
Yes it is, and no, I'm not that one if anyone is wondering... ;)

[Mark3]

~Jake (who can't resist starting a good project)

Focus man, focus.

[irish_lord99]

Focus man, focus.

Thanks man. Actually, this project would be complete if I could just find some stinkin' 1mm balsa sheets. The local hardware store that normally stocks it is out and not expecting more for ten days, and the LHS here doesn't understand scratch building. The last time I went in there and asked for balsa wood the guy pulled a 3mm sheet out of the stack (which they stack vertically *shudder*) and the wood was so warped bowed and cupped that a mouse could have used it for a skate park. He the proceeded to pull out a sanding block and told me I could use that the flatten it out. Uh... no, thanks. :)

So as soon as I can find some balsa I'll be in business. :D

~Jake

[Kristian k]

Hi,

nice project you have there... I am looking forward to see it finished :cool:
btw I read a book which said that balsa should be layed horizontally to keep it in the best shape... but in every hobbyshop I know of they stack it vertically...
can someone explain this to me?

thanks, Kristian.

[irish_lord99]

It's true of all wood, not just balsa. The reason it's not done in most hobby shops is probably because the owner doesn't know or doesn't care. I can't think of a good reason to do it that way, other than saving space for the ARF's. :)

~Jake

[irish_lord99]

Well, the peregrine is essentially done, but the balance is off so I'm going to have to add some weight to the nose. I'm not to happy about this because the plane is already 10 grams over and if I add 10 more to balance it then it's going to weigh 132 grams :mad: Target weight was 112.

That's 4.6 ounces for 157.5 square inches of wing meaning approximately 4.2 ounces per square foot wing loading as opposed to the 3.6 oz/sq. ft that the original builder was able to achieve. I'm sure I'm over because of the hardwood spars on the inner panels, but I'm not sure why my balance is off. I built the tail as light as I could and given my use of pull-pull for the rudder I would think it'd be lighter than the original.

Oh well, I'll finish balancing it and then just see how it flies. :)

~Jake

Oh, and sorry I don't have any more construction pics, I forgot to take any. :o

[GeeW]

Jake
C'mon stop mucking about and fly it! I am sure you'll appreciate the extra ballast on the windy days!

Regards
Gordon

[Mark3]

Jake, have you flown it yet?

[irish_lord99]

Jake, have you flown it yet?

Nope, so far anytime I've had a free minute it's been far too windy.

~Jake

[irish_lord99]

Okay, so SEVEN MONTHS LATER I finally got out and flew this thing. I was gone visiting the states for four months, we've moved to a new house in a new town, and life has been hectic until this past week. So I finally got a chance to take the peregrine out last weekend, and it was a hoot to fly! Just what the doctor ordered after a couple of stressful months. I didn't catch any thermals or have any long flights, mostly because I was handing the controls off to some of the local kids so they could try their hand at it. None of them had ever flown before, and a couple of them were able to pick it up fairly fast. We had a good time and I think I've got some future RC pilots here. :) Just doing my part to spread the addiction.

Even though it took a pretty good pounding from some hard nose-in landings (one on the pavement), the only damage the glider sustained was a cracked leading edge out at the tip. Easily repairable. I'm going to try and get out to fly it again this weekend, and I'll try and get some pictures then.

Cheers,
Jake

[rockyabq]

Jake, I hesitate to use the word "cute" to describe an RC glider.

But darn it, it just fits.

Nice job.

--Rocky