Basic Modern Ultralight, BMU

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BBerson

Light Plane Philosopher
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You can knock the 1/2" ball bearings out and use 1" greased bushings for a typical 100 foot takeoff roll.
I used 1/2" bolts welded on the cross tube. No wing wires on the DH53.
 

WonderousMountain

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It's not only you, there are many examples
of ultralights flying without the 1/16th weight
fraction appropriate to Gear Design. Some bust,
others just limp along forever giving sub par results.
 

pictsidhe

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Yeah, I'm swapping out the bearings in my wheelbarrow wheels, landing loads only.

I'd be ok with 1/2 if just for wheel loads. I'm not sure it's really adequate, but a collapsed gear on a UL is nowhere near as serious as the wing wires going slack in flight.

I'm getting very uncomfortable with these threads. The OP seems to have no idea about the imposed loads, what is needed to resist them or a willingness to learn.

I'm out.
 

Protech Racing

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Splits the load with the V strut ,but Ill run it again tomoroow . Should be sub 400#
It gets load tested , as does everything . I learn pretty well .
 

pictsidhe

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You experience in flight structural failure due to a woefully undersized 'Jesus' part. You plummet to a messy but quick death.

Play again? Y/N
 

bifft

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Hot Wings

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Tricycles also put side loads on the hubs,
<< >>
and so some people do build their own
And that is why I canted the front wheels on my last tadpole. I could fly the inside wheel with no worry during a turn.
<< >>
Interesting link and one of the great things about spokes: No need for accurate hubs - it all works out on the truing stand.

edit:
There was a time when people actually fixed things. I learned my spoke truing skill from my father who at one time owned and operated a bicycle repair shop. That was long enough ago that even the customers still had memories of the Great Depression and would fix things rather than buying new.
Yes, you can pound out a rim flattened on a curb impact and make it run true again.......look good too.
 

pictsidhe

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And that is why I canted the front wheels on my last tadpole. I could fly the inside wheel with no worry during a turn.
<< >>
Interesting link and one of the great things about spokes: No need for accurate hubs - it all works out on the truing stand.

edit:
There was a time when people actually fixed things. I learned my spoke truing skill from my father who at one time owned and operated a bicycle repair shop. That was long enough ago that even the customers still had memories of the Great Depression and would fix things rather than buying new.
Yes, you can pound out a rim flattened on a curb impact and make it run true again.......look good too.
Most of the wheels I laced up I had beaten the rims straightish first. It was a revelation the first time I put a new rim on. Couldn't believe how easy it was to get it perfect!
 

BrianW

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Altus SW Oklahoma
Q:
Anyone know where to get 16-20 in wheels/tires with a 1/2 in axle hole? Demoiselle style?
Thanks,MM

A: Years ago , Kitplane ran an article on DIY aircraft spoked wheels: one of their best ever!
Take a tube, two disks predrilled. Weld Get a rim and correct spokes. If you are not going to brake the wheels, they can be spoked radially. It is not hard.
 

Protech Racing

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Thanks for all of your input.
I will move the front strut/ flying cable connection to the foot box, in front of the wheel . 3/4 065 . The load is under 400# as the front spar splits the load with V strut and the front cable. Strut angle is about 52*
I had a good friend tell me that stressing an UL for 3 Gs or more was a waste of time and weight. He said that I would need 100HP and 100 MPH to see 3g. 2 G not too hard, 3 G not ever?
I did have to fly Gretchen to the ground at WOT when a micro burst blew up on my approach . I pointed it to where I thought the runway was and hard flared at about 70-80 MPH in the grass next to the runway, happy to be upright. If it was a tail dragger , it could have wrecked it bad. That may have been 2G.
I may tri gear the thing so that my Dad wont loop it. It will cost about 15# over the solid axle tail dragger. I could also stuff the 1/2 in axle inside of the 3/4 tube along with some O rings to soften the shocks. I never bent my Tandem wing axle but bent the attachment bolts a few times when the air went hot and soft, puddering down the runway at full mush.

But I have to weigh the wing parts first and make sure that the craft is feasible .
 

Hot Wings

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I had a good friend tell me
Did he do any math or consider gust loading? I agree that the average UL probably isn't going to see more than 3 G's during normal flight but all flight isn't normal.
A part 103 built per the AC and at minimum weight is capable of over 10G at 100 MPH - with enough control authority.
Getting to 100 MPH? Yes, that is a lot of hp for a typical flying lawn chair, even in a dive.

Anyone know where to get 16-20 in wheels/tires with a 1/2 in axle hole? Demoiselle style?
Thanks,MM
Take a look at suppliers for horse racing sulky wheels?
 

kubark42

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A: Years ago , Kitplane ran an article on DIY aircraft spoked wheels: one of their best ever!
Take a tube, two disks predrilled. Weld Get a rim and correct spokes. If you are not going to brake the wheels, they can be spoked radially. It is not hard.
Neat! Do you have a link? The hub seems easy, something I could machine out of a single piece of aluminum. It's getting a rim which seems hard.
 

rv7charlie

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Old articles in Sport Aviation (back when it was about experimental aircraft) talked about starting with an existing wheel (as a source for the rim) and re-lacing the rim to a wider hub, using longer spokes.
 

rv7charlie

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If you have a subscription (and the will/stamina to do the search), all the back issues of Kitplanes and Sport Aviation are available online.
 

Protech Racing

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The spar test for this airplane ;UL spars?? Tube or plank?

The wings will fold to 8.4 ft wide . It should fly on 30HP or more at 254 or less #. The fuse is 4130 welded with a "pilot box". Cuz I race cars . :)

Napkin pictures to follow .
 

Protech Racing

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Drawing the wings. I'm pretty sure that by moving the spar to 28%, that I can cover the wing in front and rear sections, meeting at the spar. This will allow me to "rib stich" the covering with rivits onto the spar .

The wings are foam ribbed with the flat bottom foil sheeted with 3/4in foam, with ribs set up on the sheet . The first 6 ft may be geodedic .
 

fly2kads

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Neat! Do you have a link? The hub seems easy, something I could machine out of a single piece of aluminum. It's getting a rim which seems hard.
Spoked wheels are popular on the Pietenpol, and look good to boot! Here are some examples of how they do it:
Wire Wheels

I have built several sets of bicycle wheels, and I concur that it's not hard. You just need to get a good visual in your head of how your spoke pattern is laid out, then just pay attention. Truing them up just takes patience, and understanding the push/pull from different directions.
 

BrianW

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Neat! Do you have a link? The hub seems easy, something I could machine out of a single piece of aluminum. It's getting a rim which seems hard.
I finally found a reference to kitplanes wheel build. It was in the March 1990 magazine.
Trouble is, I still cannot find a copy. The archive does not go back that far.

Brian
 
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