Spitfire Wing Attach Question (replica)

PSRU

Try this guy: Algie Composite Aircraft. He’s doing an LS1 powered carbon aircraft that he’s going to kit and to race. Got some good stuff on his website.

http://members.iquest.net/~aca/

Good luck on your project.

Hi AVI;

Yes this is an interesting thread. Very similar to what I’d like to do. So thanks for the heads up on this thread.

I am stuck at the PSRU and propeller stage. I firmly believe that everything else is doable, but I have to solve these two major tasks, or it’s not worth starting the project. No point in building a plane if I can’t power it.

However, I have approached this like I’ve approached everything else. Gather/read/ask/probe, and finally decide. I’m not at the decide stage yet.

It may be possible to build both a PSRU and a propeller. At 400 hp, the stakes are pretty high, though, so this is not something I’ll rush into. In the homebuilt forum I have been asking a ton of questions about PSRU’s and what drives them, (literally). There really are so few firms making them, if you discount the ones that have disappeared in the last few years (Geschwender, Cam).

I’ll try to keep an eye on Planeguy and see how he does.

Thanks again, Tom.

Elliptical Wing

Tom, ran across this and thought it might be of interest to you:

http://www.homebuiltairplanes.com/forums/showthread.php?t=3559

Tom:

Ever get a wood splinter in your finger?

There are many successful composite homebuilts and production aircraft flying.
The granddaddy of them, the Long EZ has been around for close to thirty years!
For homebuilts you don’t need autoclaves. There are also methods that are moldless although admittedly, plugs and molds are the way to go.
Homebuilt aircraft are not stuffed into huge, expensive autoclaves! Check out homebuilt glass/carbon. It might surprise you.

And, funnily enough, I know of someone who was building a Spitfire Mk1 (70% scale) using a similar method of construction to the Rand KR 1 and 2 and the WAR series of replicas.

Weight & Balance

Tom:

Ever get a wood splinter in your finger?

There are many successful composite homebuilts and production aircraft flying.
The granddaddy of them, the Long EZ has been around for close to thirty years!
For homebuilts you don’t need autoclaves. There are also methods that are moldless although admittedly, plugs and molds are the way to go.
Homebuilt aircraft are not stuffed into huge, expensive autoclaves! Check out homebuilt glass/carbon. It might surprise you.

Did you say that there’s a hundred-and-thirty pounds of ballast in the T-Spitfire nose? If that is correct, that should tell you something. The fighter pilots of fifty/sixty years ago were not the 300 lb, overweight, macho guys brought up on a diet of McD’s that fly the friendly skies of today. (Sorry guys.) Back then, they probably weighed all of 130 pounds soaking wet!

And not just airplane guys – many of today’s youngsters find it impossible to stuff themselves into the driver’s seat of an original Colin Chapman Lotus 7 !!
Everything is supersized today, including aircraft cockpits.

Ask some of the Spitfire guys on the forum. I’m sure they can give you the lowdown on the ballast.

What’s installed behind the pilot on a Spitfire? Radio equipment, a huge compass, but what else? The reason I’m asking is that maybe the GIB is so far back in the fuselage because there wasn’t room for him and all the equipment tucked up behind the guy in front. How much did all that crap that was located immediately behind the pilot weigh? And how much space did it take up?

Check out the two-seat Sea Fury, Yak 3, and P-51 conversions. Not wartime P-51 hacks but modern day conversions. The GIB is tucked up behind the pilot on P-51s because the original monster-size radios and fuselage fuel tank are sh*tcanned. On present day P-51s (with exception of those restored to original wartime specs) modern nav/radio equipment is stacked in/under the instrument panel and there is no fuselage tank. (which, BTW, created much instability when full) What was the size of the P-51 fuselage tank? How many gallons? I would venture to say the weight of the fuel would have exceeded the weight of a GIB.
You might be able to tuck the backseater right behind the pilot under a slightly extended canopy. But I think you’re still going to have to deal with the problem of the extended nose that was originally stuffed with howevermanypoundstherewere of Griffon.

Hi AVI;

I haven’t considered the Mk XVIII. I think I’m OK with the XIV, as it has a pretty massive V-Stab already.

Weight will indeed be greater with the detachable wings, but no choice here. My garage won’t house a full wing. Plus, I just want them detachable. All kinds of potential reasons why this flexibility might be needed.

The balance issue is a concern, of course. I still don’t fully understand how the 2 place Spit trainers do it, I mean with the solo flight from the front. I know there’s 130 pounds of steel in the nose, but it must just simply be a case where the CG travel is within limits whether it’s solo or dual, low fuel or full tanks. I can see how the effect of adding in a pax would be less significant on a bigger, heavier plane, but still I scratch my little head.

I work at the National Research Council’s Institute for Aerospace Research. Don’t worry folks, I don’t design critical structures! I design and machine tools, jigs, test fixtures, stuff like that, but my main bag is to be part of the composite team. Carbon fibre, fiber glass, etc. You’d think I’d be all over composite materials.

First, a lot of what I lay up, bag and bake is done in an autoclave. Pretty tough to do that on full sized spars. Even though there are out-of-autoclave materials and methods, I don’t want to go with carbon fibre or fiberglass. As you have previously pointed out with all-metal construction, you’d be building the aircraft twice, at least. You have to apply the plies of CF to a mold of some kind, vacuum bag it and bake it under resonable control. A whole new ball game, and the molds would all have to be made.

I enjoy working in the composite department, but I’m not fully sold on it’s use in aircraft, even before the very public outcry of the Boeing employee who was canned for his views on the 787. I admit that my Spitfire replica wouldn’t see the temperature extremes that a jet liner would, but I still have reservations about CF. Ever get a sliver of carbon fibre in your finger? They’re “special” and not in a good way. Can you imagine getting a sheaf of those up the kazoo in an other wise survivable belly landing?

The likely approach will be purchasing a set of plans from Terry Wilshire for an 80% Spit, doing some mods to make it a Mk XIV not a MK I, add a method for wing removal, and proceed. These are all doable things. Just do I have the time, budget and drive? Time will tell.

Cheers, Tom.

Detachable Wings and the GIB

Good choice, Tom, with the Mk XIV loback. Pretty airplane. Have you considered the Mk XVIII with its larger vertical tail?

My $0.02 worth: The primary reason a one-piece wing is used more often than not is for the simple reason that it will end up much lighter than a two-piece wing with heavier spar and spar attach hardware. Weight is one big enemy. It’s also easier to align.

As for the GIB, it is theoretically possible to place him/her behind the pilot, but what others have found is that one of the big challenges with w/b and warbird replicas is the long nose and much lighter weight of a V8, especially an aluminum LS2. You’ve got one long moment arm there and the LS2, unlike the length of the airframe, most likely won’t scale to 70% Merlin weight.

Yes, as previously mentioned, there’s the placement of fuel to consider and couplings, etc., but there’s also the landing gear attach points.

Personally, I’d say build a one-piece wing, even if you have to rent a hangar.

And secondly, why not build with composites? Build time with composites will be faster and given the cost of quality aircraft grade wood these days, probably less expensive in the long run.

If you’re going to build with wood, why not save yourself a bunch of time and build from one of the plans sets available? The designers have already done the math – all you have to do is to build. Purchasing a couple of sets of plans will be money well spent!

Check out the Falco from Sequoia in Richmond, VA – it’s a wonderful wood homebuilt, with a one-piece wing.

Hi Dazdaman;

When I mentioned easier, I should have added from the construction point of view. In fact, short of building another shelter, the garage is my only room large enough to build the main pieces of this replica. I would have to make the wings as separate units and bolt them on. No if ands or buttocks.

Aside from building, I still want the option. I can envision situations where I want the wings to come off for storage, trailering, whatever. So that’s how I’m proceeding. Even though I wouldn’t want to take them off often.

Here is a sketch of my current detachable wing concept. It borrows ideas from many people, so it’s not something I can take full credit for by any stretch. The colourful metal plates would also be on each end of the stub spar, a little wider so that the wing metal plates could slide inside the stub spar plates. The drawing isn’t quite to scale, but it’s the concept I’m showing.

QLD Spitty, I hadn’t even thought of this from the maintenance perspective. Good point. I wonder if it would make sense to add in shut off valves for coolant so it doesn’t have to be drained. But that adds weight doesn’t it. Some services or connections should be designed for a quick disconnect.

As always, I welcome constructive critiques, and I appreciate the thoughts so far. you guys should send me a bill or something.
Cheers, Tom.

It,s bent…

Wing removal is something you look at also for maintenance.If you have fuel tanks in the wings and spring a leak,can you repair it by using access panels or would you need a wing removal.Remember a good engineer makes life bl00dy difficult for the maintenance guys. :p

Hi Dazdaman, Mk I and Mackerel;

First, thanks for the replies. I can see that you guys have indeed thought about the whole wing detach issue.

So in order;

Dazdaman, you;ve asked a fundamental question, “Why do I need to detach the wings at all?”

I have this nagging feeling that hangering the aircraft may, at times, be more challenging than I’d like it to be. I haven’t checked into this, although I should. If I run into problems, I’d like to have the option of storing this beast at home in the garage. Not to mention the fact that that’s where I’d build most of it. My garage is probably long enough to do the fuselage, but it won’t hold the wings done in one long piece. My plan is to create a jig and do the wings side by side, parallel progress style.

I am sure that I would be saving complication, but the reasons are strong enough for me to at least seek out the possibility of removing the wings.

Why should it be more challenging? A 3/4 Spitfire wingspan is 27.6ft – not much smaller than most Cessnas I would imagine, and not a huge amount larger than most homebuilts anyway (Bowers Fly Baby wingspan – 28ft).

Aside from storing the aircraft (for repair etc), I can’t envisage any other need for removing the wings at all. And, unless you put together some sort of simple solution to fitting the wings back on, it’s going to be a pain in the **** to keep removing and refitting the wings each time, and DEFINITELY not a one-man job.

The Spitflyer project I mentioned before has a “swing-wing” capability which enables the wings to be stowed alongside the fuselage, but still attached to the centre section (like a Fairey Firefly, for instance).

Hi Dazdaman, Mk I and Mackerel;

First, thanks for the replies. I can see that you guys have indeed thought about the whole wing detach issue.

So in order;

Dazdaman, you;ve asked a fundamental question, “Why do I need to detach the wings at all?”

I have this nagging feeling that hangering the aircraft may, at times, be more challenging than I’d like it to be. I haven’t checked into this, although I should. If I run into problems, I’d like to have the option of storing this beast at home in the garage. Not to mention the fact that that’s where I’d build most of it. My garage is probably long enough to do the fuselage, but it won’t hold the wings done in one long piece. My plan is to create a jig and do the wings side by side, parallel progress style.

I am sure that I would be saving complication, but the reasons are strong enough for me to at least seek out the possibility of removing the wings.

Mk I:

I hate that when I type up something perfect and it disappears! Happens often enough.
I agree with you that taking off the wings would not be a snappy little task. It would take time, for sure. This is not meant to be typical, just doable in an “emergency” situation.

I really do have to check into hanger availability, but it’s so long before that’s even an issue (if ever).

Mackerel:

Building a real Spit would be killer expensive. Merlin engine, actual metal parts
built to exact scale. Not possible for me.
The balance issue is certainly a concern, and other than ballast in the nose, I don’t fully see why the two-place Spit can be soloed from the front. Unless, of course, the extra person just doesn’t make the CG travel that much rearward.

Well, thanks boys. If I lived on a hobby farm with 1000+ feet of flat land, I’d not worry about the wings being one long piece.

Cheers, Tom.

Spitfire wing attachment (replica)

Hi Tom Kay,
If you are going to all this bother why not build a real one ?!!!!! If you intend to have two people in there have you thought about centre of gravity ? the other person in a two seater wasnt positioned between FR13 and FR14 for nothing.

Spitfire Wing Attach Question (replica)

Hello Tom:
All I can add is ditto Daz’s remarks. I had a long winded reply to your questions on this thread typed up over a week ago and then lost it somehow just prior to posting. To summarize, my Spit is built the same as the Jurca’s and Terry Wilshire’s, in that the wing is one piece and bolted to the fuselage. The box-beam spar fits up to the backside of the firewall and the lower engine mount pick-up bolts tie the whole works together essentially as one unit, with a minimum of shear planes. This configuration is very strong, simple to build and the most weight conscious I know of.

My only other comment (from the soap box of course!) was that after going through all the trials of scratch building a flying replica Spit, I suspect the last thing you will want to do is take the wings off it every time you are finished flying (if that indeed is what you are planning to do). Garage storage wears thin on wives (even if its only one bay), particularly after you have had the entire garage tied up for 5-10 years building the airplane. In my 40 some odd years of flying in the Canadian general aviation/homebuilt community, the only exception to the “don’t take the wings off creedo” is the sailplane types (for obvious reasons). I can assure you that if you build a sweetheart of a replica Spit (especially a 2-holer), you will have plenty of offers for reasonably priced hangar space. I’ll step down off the box now.

Good luck in landing on the design that gets you to the first sawing of wood. And by the way (….back on the box again for a split-second), good on you for reverting to wood. It will get you flying a whole lot sooner than all-metal ever could and you will end up with a far better looking (closer to scale) aircraft (ref. Ferguson, Wilshire/Cutting or Deford Spits as the best examples). I’m hoping my old Longstaff Spit will come close to their league when I’m finally done all the mods and refinishing.

Regards, Mk.1
——————

I was having a think about this, and I’m wondering why you REALLY need to make the wings detach at the root? OK, from a scale point of view, yes, I can see that. But the Jurca Spits (both 75% and 100% scale) have wings which are built in one piece, that join onto the fuselage by using bolts (I think). The Isaacs Spit is the same. The fuselage is lowered onto the wing spar and then bolted in place.

I’m not expert, but you might be saving yourself some unnecessary complication by doing it this way, rather than building it as per the full-size?

Dazdaman;

Funny you should mention that. I have increased the fuse in width and depth, mostly with the goal of squeezing in a second body.

It really is a back and forth process, because when you go too far, it looks like a cartoon airplane with a silly bubble for a canopy, but when you don’t go far enough, only underfed pygmies could fit in. So it’s all about balance I suppose, and of course, compromise.

I went through my old posts. I tended to gloss over the wood related thoughts, but now that it’s looking more like the building material of choice, I read through them more carefully. Then I had a look at the Jurca Spitfire, and others. The Tally Ho’s construction methods certainly have me intrigued. I like the way they’ve done the fuselage longerons and engine mounts, amoung many other things.

Well, thanks for chiming in. Tom.

Scale the fuselage up a bit more (say 80% scale) to get your bodies in, but keep the wing at 75% – allows (so I’m told) for better penetration through the air etc…

Hi Stuart;

Good question, and I do have reasons why I want the wings detachable at the root. Mostly smallest possible storage “footprint.” It also, has to do with building it, and garage space available.

Richard, I haven’t made firm choices about wood types yet, but here’s what I’m thinking, subject to change:

fuse frames 1/2 or 3/4 plywood, (Finnish Birch?)
Spar caps and fuse longerons, laminated Sitka spruce
spar shear web plywood, thickness, number of plies, not yet known
skins for wing and fuse 2 and 3 mm plywood type??

I will draw on experience of others, if I choose to proceed with the project. I like a lot of the features that I see in Terry Wilshire and Bob Cutting’s Tally Ho project, for example. I might look into Jurca’s 75% wood spit to see what it’s like.

Thanks, Tom.

Hi Tom, what wood will you be using?

Better attended yes, but not by joiners! is there a reason why you want the wings to detatch at the root, rather than a usefull distance out, i.e 8ft width, for roading, or under 12ft for gateways etc; obviously the further out the join, the less load taken by it.