jerrybern

All wood except for the aluminum. wing tubes and the landing gear Covered with glass cloth and West Systems resin

Halcyon66

So about 95% wood then

Regards,

jofunk

I guess we need the definition of "large scale wooden turbine models" that will draw a line in the sand that shouldn't be crossed. Is it 100% wood? But there is no definition of wood............................... BTW beautiful wooden Vampire Jerry. I hope Kerry Sterner didn't cross the line in the sand when he drew the plans.

jerrybern

oops, my mistake, the canopy is vacuum formed plastic and the drop tanks are epoxy and cloth, does that take away about maybe another 1 or 2 % of the actual build.

jofunk

And the Wright bros. first flight could have been done on the wing of the Spruce goose.

Ron S

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I guess the original poster was asking about a large, all wood swing wing model, and somehow this thread got morphed into "can an all wood turbine model be built?"

I agree with some things pointed out by others. Other than a Me-262 kit, I don't see any range of jet models in their offerings - mostly WW2 warbirds. It's a pretty tough jump to go from those model types to a large all-wood swing wing (that has to be kept under 100 lbs, atleast in the US). Passing wing shear and bending loads into what appears a pair of plywood lugs into a ply torquebox will be a trick.

Their pics clearly show atleast one kit has been cut. It would go a long way, if FokkeRC would actually build and test their own design, then offer it to others. I hope they're building one now - it will be neat to see, and a lot of knowledge could be gained, that can be refed into the design.

jofunk

You Are correct Ron. But the comment that morphed the thread did not reference swing wings........ hats off to your Su 17 it is very impressive.

Halcyon66

Really what do you think the "Main Spar Box" is on the B1?

Once again in regards to wood, you agreed that you could never make the Goose of out wood. The Goose started as one thing and then morphed into another by Hughes.

Anyway we can go back and forward yet best for you to find the memoir of George A. Spangenberg, he was an aerospace legend on the Navy side.

I have a copy somewhere yet he writes about the Goose, as he was actually there and talks about parts failing at 50 or 60% of their design load from memory.

I am sure others have read it.

Regards,

jofunk

"large scale wooden turbine models".........Plural. That was the comment you made that morphed the thread. That means all large scale wooden turbine models, not just the swing wing that started the thread. Wood airframes can be built large and safe or small and dangerous. The same goes for composite airframes, turbine or prop.

So did you ever figure out how much birch wood made up the balance of the 300.000 pounds in the goose? Don't forget to subtract rubber floor matts and Leather seat cushions otherwise the answer will look like a crazy amount of birch wood.

franklin_m

In in a level banked turn, speed is irrelevant. G = 1/cos(AOB). Since you measured 8g's, then it was either not level or greater than 60 AOB.

Aerospaceweb.org | Ask Us - Bank Angle and G's

Halcyon66

OMG, there is a limit to them due to the simple fact of mathematics.

I can go into this further yet again most comments I have stated you have finally agreed with, it what is a very roundabout way.

The Goose was a composite aircraft, end of story. I have a considerable aviation library as I love aeronautics and math's, and they go together. You can literary find anything in regards to high end factory blueprints, loft lines and the like on any significant airframe since the beginning.

The Goose, almost nothing. You indicate 300k lbs, so then with the load of 150k lbs that is a total of 450k, hp from the wasps was a supposed 3000hp. So 24k hp in total, prop losses and parasitic drag will give you maybe 75% of that number, engines also had issues with back cylinder cooling which would reduce the hp. The other point is no one actually knew in the end what it's all up weight was.

So (24,000 x .75) / 450,000, or 0.04. The LD on the airframe was impressive yet again most of the supposed numbers came from calc's not real time measurement.

The biggest actual flying aircraft at the time was the B-29 and it was 0.073.

So on top of that you had a huge frontal drag as the front end was the equivalent of a brick and the other nasty part of it all was the hydrodynamics. Even though would could say it was a planning design at that weight is all displacement and the stresses would have been enormous. Add to that the wetted area of the hull and there would be some tricky numbers.

You indicated that it was have turbines at a later stage, that would have required a redesign and new structures and there we are at the law of diminishing returns again.

Again going back to an earlier comment lack of info is because Hughes never let anything leave the building. I have 100's of thesis on aircraft with FEA and CFD which are great reading. Why has no one done one on the Goose, as few would believe it. Could even be classed as heresy.

Hughes was over budget and way behind schedule. He could have had serious consequences from the US Govt, he said it will fly and if it doesn’t he will leave the US. He ended up a recuse in a hotel in LV, not sure if that was a win.

Again why let the truth get in the way of a good story,

Not sure what the point was in regards to the Wright's aircraft being able to fit on the Goose's wing. The B-29 could have as well, difference is that they both flew longer than the Goose.

Now if the Goose was made of ALU, it would have been a completely different story.

Hughes was a legend, that has never been in doubt. Glomar Explorer now that was a whole other story.

Regards,

jofunk

I agree with the math limit statement in regards to large wooden model turbine airframes. It's the dimensions of your model shop door.............. See how fun and informative this is. All the info you provide about the spruce goose. H66 you seem to be good at extrapolation and reasonable assumptions. Just one more fun fact about the goose if you can provide it. It is a fill in the blank question. The Hughes H-4 Hercules had X tons of birch wood in the airframe. You can qualify it as in composite form. I know you can come up with an educated guess.

Halcyon66

Composites of the day used around 80/20

Nowadays it can be 60/40 yet depends on the matrix.

Or another note was emailed a link to the George Spangenberg Oral memoirs

https://airandspace.si.edu/support/w...ge-spangenberg

gasoralhistory.pdf

TAPE 5 of 16, SIDE A

Starting on page 66.

It would be a waste to download it and just read that section, the whole memoir is an amazing read.

Regards,

invertmast

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hence why i said “to keep it within the confines of an average flying field”.

to maintain the same radius of a turn at varying speeds to remain within the same physical “ground space” requires varying bank angles at varying speeds with various G-loadings. The bank angle may not of been exact at 60*, but that wasnt the point of the comment, the point was that G loading is substantially greater *at times* for our models than many would suspect.

other than some fiberglass cowls and gear doors, this models airframe was 100% wood. Its now about 25% composite after a few years worth of modifications and upgrades.

Ron S

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That beastie is pretty cool looking… 🤓 I hope to see it one day. There used to be several parked (storage) at an airport near Tucson, and I think there is a flyable one based in Dallas.

Didn’t Kerry Sterner build one long ago?

Viper1GJ

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Great looking airplane... is this at Harrisonburg, VA?
Gary

Halcyon66

Outstanding builds, the F-14 thread was a great read as well.

Rough fuse, wing layout shows volume limited example of a 1/4 scale F9F.

Total volume = 52348334.38 cubic millimeters

Fuse volume = 17948861.31 cubic millimeters

Wing volume = 34399473.07 cubic millimeters

Therefore in this case the fuse is 34.28% and the wings are 65.71% in volume terms, the fuse is basically a thickened hollow cylinder and the wings are solid foam. I have just used a 10mm thickness of the fuse which should take into account formers and the like. I would think 6mm would be a better number yet lets go big.

The foam nose is not added as are the wood tail feathers, probably cancel each other out volume wise.

Intakes would need to be done and added to the wood volume, yet would see potentially 4% additional volume. Also not used the tip tanks.

Therefore in the case of the F9F it is impossible that the airframe is 95% wood. One could CAD the whole thing up and get an exact result yet I think the above illustrates the point.

The Vampire model is would probably be closer to 90~95% wood volume as it is actually all wood.

Regards,

invertmast

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thanks Ron! She’s a beast. Kerry Sterner did do one a few years back. This one is substanially larger though.

im hoping with the latest upgrades to fix a few performance issues (currently at around 18lbs lighter in one component alone). If that happens, i’ll mold and do a fiberglass fuselage next year and likely a pair of turboprops.

invertmast

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thanks Gary! It was at the vrcfc club. This was taken about 4 years ago, its gone through alot of changes since, including a functional variable sweep composite canard.

sysiek

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