# THE PIETENPOL AREA

Discussion in 'Classics' started by HIGHRIDEZ, Feb 9, 2017.

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1. Feb 10, 2017

### rbrochey

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I priced the Scout fuselage materials (I would do the cutting, shaping etc. in my shop) for between 3 and 4 hundred dollars using beautiful, tight, vertical grained Douglas Fir... that's the route I would go... and when I asked Andrew Pietenpol about using fir he said that's all his grandfather used. But going the kit route is a good idea too.

2. Feb 10, 2017

### lr27

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If you want large diameter wheels, I suspect that spoked wheels can be significantly lighter. The Sky Pup gets by with plastic BMX wheels at a gross weight of 400 lbs. (In real life, more, I should think.) Stall is 28 or 30 mph. The Piet grosses 2 1/2 times as much and stalls at 35 instead of 28. Actually, I think that's a bit optimistic, since it implies a Cl of 2.3. I think a more realistic Cl would be 1.7. In that case, the stall would be around 41 mph. If we assume necessary strength goes with the square of the speed and proportionally to the weight, then you need wheels that are 5 times as strong as a plastic BMX wheel. That shouldn't be very hard to achieve. A rear wheel for a tandem "mountain" bike would probably do, though you'd have to modify or replace the hub. I guess that's a bit large, but there are aluminum BMX rims that appear quite hefty and have a quasi-infinite number of spoke holes:

I think these would be far stronger than those plastic wheels and therefore suitable, except for the spoke pattern. Especially with extra wide hubs. Or just take ordinary rims and add more holes.

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3. Feb 10, 2017

### Turd Ferguson

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At one time all cars had spoked wheels, as they evolved from wagon wheels! A car wheel is not comparable to aircraft applications because of the width but if you look at the load ratings, standard Cleveland wheels have a higher static and much higher load limit than car spoke wheels. Absorbing the landing loads is the challenge, the side load only complicates things. A motorcycle rim flexes quite a bit and when that happens, spokes get loose and wheel loses strength. Any side loading at that point and there could be a problem. Then there is the weight issue and will a spoke wheel be a penalty.

Despite the limitations, I decided if I ever built an antique airplane, I'd probably put spoke wheels on it. I'd build my own hubs so they would fit a standard aircraft axle, etc.

4. Feb 10, 2017

### lr27

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Wait a minute. Where do you get the static info for car and other wheels?

BTW, here's an image of one way to do a hub. Each hub would have two halves, with some standard metal tubing to connect. Mentally add all appropriate fillets, chamfers, etc. and rescale to suit.

5. Feb 10, 2017

### Autodidact

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That just seems like a too broad and sweeping statement. There are many different spoked wheels for cars with many different load ratings.

Anyway, to illustrate a point, this Isaacs Fury has flown for many years with wheels and brakes from a Vespa or some other old Italian motor scooter:

6. Feb 10, 2017

### Little Scrapper

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On wheels.....

Don't reinvent the wheel, pun intended. Lol.

Here's a great light wheel option. I just took some photos for you, these are extra Harley Davidson wheels from the 70's.

Back in the 70's Harley offered an upgrade with wheels, like a $20 option I think. The upgrade was for Aluminum Borrani hubs and wheels. Borrani Company has been around since the 1920's and they were the OEM wheel supplier for Alfa Romeo, Maserati, Ferrari etc. They also made motorcycle wheels......awesome wheels. These are light weight but have a special reinforced shoulder for racing. All that means to you is they take heavy abuse. They are dirt cheap and available everywhere. If you go with a 19" front HD wheel, tires are plentiful and dirt cheap. If the rim bends you can straighten it with a leather mallet. Or send it to Buchanan's and they will straighten it. They use leather mallets too. Here's my 19" front Borrani for a 76 Ironhead. Spokes. Instead of custom spokes just order standard HD shouldered stainless spokes from Buchanan's. Cheap and available. The hub. Obviously the hub comes with a disk break flange. Have a buddy with a lathe spin the lugs off, or I will do it for you, either way, it makes it lighter. And as long as it's chucked up bore the center for a bronze friction bearing. And as long as it's turning, polish it up. Flange. Opposite side. Side view. So that's what I would do. A$60 shinko tire and you have yourself a bichin set of Italian wheels that you know will handle the abuse. I hand lace my own wheels, lots of people do. There's probably a few million youtube videos to teach you.

Any how, that's how Scrapper does things.

Last edited: Feb 10, 2017
7. Feb 10, 2017

### Little Scrapper

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Shinko 270 tire. These are like the old Sears and Firestone tires from the old days. I have bought numerous sets of these and they take heavy abuse and are pretty light weight.

Or get the expensive remakes from Coker Tire for that real authentic look.

8. Feb 10, 2017

### Turd Ferguson

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The dirtbike version in the '60's and '70's were from the spanish company Akront. All the snazzy European MX and dirt bikes had high shoulder Akront rims. When they closed another company bought the tooling so I think they are still available today.

9. Feb 11, 2017

### Autodidact

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Sorry, I didn't mean to hijack the thread.

As far as looks and even utility in most places, the spokes can't be beat and I love the way they look, but some areas have very squishy soil and some kind of balloon tire would be almost a necessity, unfortunately though because they aren't very nice looking.

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10. Feb 11, 2017

### Vision_2012

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Scrapper, you guys have my head spinning...
" Obviously the hub comes with a disk break flange. Have a buddy with a lathe spin the lugs off"
So the intention is NOT to have brakes?

What is a good source for axles, hubs (with bearings), brakes, spokes, wheels, inner tubes and tyres? Can this be done at one source? Or do you go to craig's list and try to buy two used motorcycles that may happen to have the same front wheel, tyre, etc. and scrap the rest?
I'm asking because I am not from the motorcycle world, wouldn't be caught dead on a motorcycle, know nothing about motorcycles, etc. I have been all over Piet sites, and they look very enticing with motorcycle spoked wheels, but nobody tells of how they get the whole thing done like it's a secret. I even have a set of GN-1 Aircamper plans, read website logs and read the forums.

Perhaps there is a business opportunity here for some motorcycle guru that is now into HBA...

11. Feb 11, 2017

### Little Scrapper

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I grew up in the motorcycle world and have multiple motorcycles but honestly, that doesn't mean anything really. Spokes and lacing is a math equation, not a problem.

But the easiest way to wheels are of course to get complete units. This takes the thinking out of it. By the way, in the old days motorcycle wheels were used so it is period correct.

Anyhow, Buchanan's makes spoked with a machine so they can get you anything you want.

Personally, aluminum Harley Borrani from 1974 - 1980 Sportster (ironhead) pre evolution are ideal as far as motorcycle wheels go. Pick a size where wheels look good but are readily available with cheap parts. So 19 or 21". 19" probably looks good. EBay has them all day. I have multiple sets on shelves, they are literally everywhere and cheap.

Brakes. If you think you want them I'd personally do mechanical brakes and screw a good cart hub to the aluminum spool. Any small engine place has a "Stens" catalog with brake parts. I wouldn't do brakes but that's me. If you are on pavement most of the time then yeah, brakes are good.

Don't fear this issue. Seriously, you're over thinking it. I have most service manuals for sportsters and ironheads and they give spoke lacing patterns. It's very easy, even for a first timer.

Now, you can also go modern and use motocross wheels. Just remember the wheel you pick has a size and that size determines what rubber is available so choose wisely.

Would I be afraid to make my own hub? No, but I think it's rather dumb considering there's a 100 years of motorcycle wheels available for cheap.

70's mopeds had light weight spoked wheels but the shoulders on the rims just can't handle loads well, that's why Borrani wheels are ideal. Super light weight and extremely strong. The hubs can be machined down to save weight even though they are aluminum and light already. I'd totally ditch the heavy bearings use a friction type bearing with a grease fitting. This will allow you to eliminate the 5/8 or 3/4 harley axle and go to a full 1-1/4" tube axle similar to the Cub. Strong, light etc.

Just don't over think it, it's a Pietenpol. Ask yourself, what would Bernie do?

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12. Feb 11, 2017

### Tiger Tim

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On 626 (blue and silver one shown earlier) I'm told the wheels are off a Jenny and they very well could be. In any case, the hubs are just steel flanges welded to a steel tube, laced to a fairly featureless rim and of course no brakes. I forget if there are bushings at all in there, I had the wheels off to re-grease them once but apparently didn't pay enough attention. The axle is a straight tube with a couple fittings welded on to retain the wheels and to keep the axle properly captured side-to-side.

Normally I'm okay in an airplane without brakes. Balloon tires as on most that I fly take an awful lot of power to get moving on grass anyways. Not so with tall spoked wheels and even at idle the Piet sometimes likes to start on its own towards the runway. Chocks on a long rope would be a good idea for the aspiring 'as original' Piet pilot, but cheating and adding some brakes onto the thing might be better. Mechanical would be good enough and I'm not sure I'd bother with differential, just something with a single handle on the left side of the cockpit (for your throttle hand) to hold it back for run ups. Just remember that with the Jenny-style original gear it would be important to add a link in the suspension to keep the axle from rolling when brakes are applied, I believe details of such are on West Coast Piet.

13. Feb 11, 2017

### Little Scrapper

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If you make your own hubs it's best to recruit a machine shop that has an index head so the spoke holes run concentric, true, equally spaced etc.

I would weld a oversized spool first then true it up in a lathe and take it down in size. If you're not a good welder then machine it up from a solid piece. See the problems here? This is why motorcycle wheels are just smart.

I guess I could probably weld you up a set of spools but I don't like the liability part. I have a lathe but no index table for holes. I do have machine shop customers so I'm sure I could help you with that as well.

You're still out the rim. So, if you make a hub what rum will you use? Hub width matters, quantity of spokes matter, size of spokes matter.....see what I mean?

The guys who build pietenpol wheels do it either for the fun challenge or the "old school" look, which doesn't make sense to me because motorcycle wheels ARE old school.

14. Feb 11, 2017

### Turd Ferguson

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The advantage of making your own hubs is they can be designed to fit a standard aircraft axle.

A milling machine with a DRO will drill the flange holes with no dividing head

15. Feb 12, 2017

### lr27

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Just how accurate do those holes have to be? Spokes have quite a bit of adjustment built in.

I've built a few bicycle wheels, which were fun and satisfying. Besides, how else are you going to get radial spokes on the outside and 3 cross on the brake side? (In my case, radial spokes on the front. But I've heard of radial spokes on the left and crossed spokes on the right to take the drive load.)
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Do motorcycle wheels use the same general type of bearing as the simpler bicycles? If so, I guess you could pull the bearing cup and press in a plain bearing machined to fit.

16. Feb 12, 2017

### Little Scrapper

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Tupical bearings are heavy and not required in a airplane like a a Pietenpol. They only roll for a short period of time, the rest is in the air or sitting. A light weight option is to bore the hub and sleeve it to fit a 1-1/4" axle.

Spoke holes don't need extreme accuracy but if you use a motorcycle hub the accuracy already exists.

Lacing patterns are kind of irrelevant unless you're using a very borderline or marginal product like a bicycle wheel. There's no way I'd use a bicycle wheel on a Pietenpol.

Spokes on a wheel are two sides of a triangle, the third side of that triangle is the hub and it's width. The Lacing pattern is less critical than the you think. Motorcycle companies have already done the math and engineering. That's what's nice about using existing product. This why the Pietenpol guys who have built wheels have made the hubs so darn wide, it's my belief these home made wheels are marginal in strength. Of course, it doesn't seem to be causing accidents so I guess they are strong enough.

Designing a new hub is fine if a person wants to spend the time and feels there's value in experimenting but these things take time and at some point you'd want to actually fly the airplane instead of constantly experimenting..

If I were to design one, which I wouldn't, I would machine in on a lathe out of solid bar stock. It would be quite easy on a lathe.

The rim I would use would probably be a aluminum motorcycle rim used in racing.

17. Feb 12, 2017

### TFF

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Although they dont grow on trees anymore, you can get a couple of CB550 front wheels with the disks and calipers, make some heel brakes and be done with it. The Piet guy at my airport did one in wire MC rims and the other in aluminum mag but put covers over to give it the WW1/post WW1 look.

18. Feb 12, 2017

### Little Scrapper

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They made a lot more other bikes besides the 550. The 550 was only made for 4 years, cb750 parts are much easier to find.

You can search other motorcycles too, suzuki, yamaha etc. Just pay attention to weight in both the hub and rim. Also, tire availability when it comes to width. The older the bike the narrower the rubber......generally speaking.

As a bike collector and owner of several CB series of bikes, please don't burn up our limited supply of CB550 parts. That's just mean.

19. Feb 12, 2017

### Pops

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Off topic, but LS, when I get the JMR finished this summer, I've been wanting to build a VW powered Trike. That would be the best front forks and wheel to buy for the project. I welded up a frame for one about 30 years ago for a friend but forget what I used at that time.
I sold my 1968 VW Bug with an Buick aluminum block V-8 engine and don't have anything fun to drive now, so thinking a VW powered trike will be the fix.

20. Feb 12, 2017

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