Torpedos with Wings - race plane

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Starman, Mar 14, 2014.

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1. Mar 14, 2014

Starman

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Inspired by the twin fuselage race plane thread ...

So it looks like what we need is a two seater torpedo with wings

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2. Mar 14, 2014

Starman

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The main reason I like the long shaft is because I will use it to great advantage using advanced torsion bar technology. The fact that it transmits much less torque and can be lighter is a part of it too, of course. If we want a prop rpm of around 2500 and the engine is running around 7500 rpm then that's a three to one reduction (for racers, cruisers would want more like 2 to one (5000rpm))

Torque tubes were mentioned in the twin fuselage thread as being already in use but those are not acceptable for what we need. Those torque tubes are the smallest lightest weakest they could possibly be, barely adequate, which is what the engineers are required to create, so it's all good, but barely adequate is also borderline inadequate.

Anyway, here in the real world, described best by Taoism, difficult problems are only really solved with softness. So the torsion bar works like this:

The bar should 'wind up' at least 90 degrees at full torque, and it needs to have the ring gear of a planetary gear set attached to act as a flywheel at the end away from the engine. This will ensure that the resonant frequencies of the drive system are very low and that the gearbox will see absolutely no power pulses. In order for the bar to twist 90 - 180 degrees at the diameter required for the high torque output of a supercharged Hemi it needs to be at least four feet long, and five or six is better.

What I had intended on that drawing was a cruciform tail.

Here's a question for autoreply, does a two seat side by side sailplane have substantially more drag than a single seat.

Last edited: Mar 14, 2014
3. Mar 14, 2014

Starman

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I wonder if a supercharger is better than a turbo? With a supercharger you can point the exhaust stacks straight back and get a lot of thrust, and this is the kind of thrust that increases in effectiveness with higher speeds, isn't it?

4. Mar 14, 2014

N804RV

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As soon as I saw your line drawing, I thought of this:

This is the VmaxProbe

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5. Mar 14, 2014

Starman

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or like the LH-10, a two seater, it goes 230mph on 100hp, so it would go 460mph with 800hp, with fixed gear! With retracts and around 1500hp it should zip along fairly well.

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6. Mar 14, 2014

bl_dg

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Put those counter-rotating props on the front, a little forward sweep to the wing and you've got a Bugatti Model 100 racer. To make it a challenge for the masses, keep it to something a little more affordable, like the Formula V size racers.

Engine limited to 2.0L (could be VW or other auto conversion)
Take-off weight limited. (less than 500 lbs?, 600 lbs?)
Set a max stall speed.
Objective is max speed. ( score by [max speed]^2 / [stall speed] )

Let's go racing!

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7. Mar 14, 2014

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Yes. Offset-seating helps a great deal. See the Binder EB29D how to cram two people in a minimal fuselage.

The LH10 never came even near it's promised performance.

8. Mar 14, 2014

Starman

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I refined the sketches a little bit and added component locations. span is 20 ft, wing area 24 ft, and assuming 3000lb then wing loading is 125 lb/ft. Turbo exhaust providing thrust, and triangular wing root cooling air intakes. Green is fuel and blue is cooling.

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9. Mar 14, 2014

JamesG

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One of Davis' DA designs? They were very torpedoy.

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10. Mar 14, 2014

Starman

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Maybe you didn't read the first post, but this is about an 'unlimited' race plane that isn't limited to the 'unlimited' race plane terribly limiting rules.

Were talking monster 8 liter V8s here, so please take your Volkswagen elsewhere.

11. Mar 14, 2014

Starman

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Yes, but might experience some flutter at over 500 mph =)

Seriously though, the laminar pushers are the ones with the most promise for highest speed.

12. Mar 14, 2014

Starman

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I was thinking about what kind of rules would be helpful for this new supersport class of racer, and have some of the following suggestions.

Capacity for 2 - 6'3", 200lb - (2m, 90 kilo) - people carried comfortably.
1000 cu. in. (16 liter) max. piston power.
Internal fuel capacity for 1000 mile range at 400mph, but only carry enough for a race.
200 mile race on a large closed course that is designed for top speed rather than for who gets to the first pylon first.
Rollover protection

and then these:

A maximum landing roll out distance? (for passenger jet sized long runways)
Props only, no fans?

Last edited: Mar 14, 2014
13. Mar 15, 2014

Brian Clayton

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race from coast to coast? Not really good for spectators, but it would be big fun to gamble on....

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14. Mar 15, 2014

Aircar

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The V max probe was actually quite dumpy in the fuselage and had it's maximum thickness quite far forward also --plus fixed gear and four tail intersections vs only two for an inverted V . The inverted V as landing gear also allows for a single monowheel and very simple retraction as well as a 'gravel catcher' . Maybe you could overlay the HP 18 pod and the V max to the same scale to see the difference , it was a miracle that the SCALED team could shoehorn the 1000hp Nissan engine and all accessories into the same diameter as the HP18 but they did it --that is the basis for massively upgrading the original "super BD5" concept from 1974 (the peak of the BD5 fad )

The very first tail pusher with a straight shaft was called "Aerotorpille" (maybe a bit wrong in the spelling ) literally 'air torpedo' --and none of that type has ever been successful since because of the drawbacks that centre around the CG height and gear length etc --the original Cirrus tail pusher (VK30) was abandoned and they returned to the traditional "Bleriot formula" nose engine and prop and aft tail . But for a one purpose design those drawbacks can be minimized as described and the rest can be lived with. Not having a main gear failure to extend is crucial --obviously , and being able to jettison the prop is also probably desirable ( I say 'probably' because the XB42 had a cordite charge to severe the prop and associated gearboxes but when it was used the aircraft pitched up violently so that bail out would probably have been impossible anyway just from the G (and you better hope you are wings level at the time...)

The real question is -would you be able to (permitted) sell rides in such a thing ? (how do ex warbird joyflights work if there is no certification? ) it is obviously far far less logistically compared to taking a fling to the edge of space and plummeting back with Mr Branson --and very very much cheaper .

I have looked at both side by side and tandem and 'other' configurations .... the side by side (or staggered) can be made as low a drag as in tandem and gives a much easier grouping of masses and the integration of two engines into one or two rear props (but that is not a push over either -the Learfan foundered on the two into one gearbox trick. ) The Douglas Cloudster (small civilian follow up to the XB42 had such a configuration and worked but the collapse of the civil small aircraft market killed it off -and the Lockheed Big Dipper by Thorp ,another tail pusher . The Planet Satellite ,BD7 Grinvals Orion and too many others have come and gone without revolutionizing anything so it is a minefield to enter this area despite how attractive it appears . But a faint heart never won a fair maiden...

15. Mar 15, 2014

Aircar

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I would not go for such a high aspect ratio for the racing mission and the flutter risk -- stiffness is a function of L cubed so there is a lot lost by spreading the area over too much span and you could save a lot more area in your fuselage and tail . Now for a two seater three view.......

Here are two links to the original flying torpedo http://www.freewebs.com/aeroscale/aerotorpille.htm

and http://flyingmachines.ru/Site2/Crafts/Craft28593.htm --there were contemporary German and Russian tail prop pushers also.

16. Mar 15, 2014

Aviator168

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So what is the real world performance of the LH10?

17. Mar 15, 2014

BoKu

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Anybody who wants to try this, I still have two HP-18 fuselage pods left. If you pick them up FOB Murphys CA, I'll let them go for $200 ea. Starman likes this. 18. Mar 15, 2014 Aircar Aircar Banned Joined: Feb 20, 2010 Messages: 3,567 Likes Received: 367 Location: Melbourne Australia Oh the shame of it ! is$200 all that a year of a man's life is worth ?:gig: If only I was 7000 miles closer..... Now that you are on line Bob how about describing your "18 based go fast dreamship design? BTW do you have canopies for those pods ? (not sure if Dick went to mecaplex for production canopies either -do you know ? The HP24 forward fuse is another candidate and 'in production' --I am not sure if I would not want a couple of inches more headroom than the 18 in any case --just hitting turbulence at some ungodly speed could make contact with the canopy a risk . Thinking back on it -we used to have a Siai Marchetti SF 260 based at my old airport (Essendon) and in the next door hangar (I finished up repainting it and retrimming the interior when it was sold but never got to fly it -****.)

It returned once with about one foot of the fin sliced off after hitting a cable slung between the sides of a river valley and on another occasion with a big hole punched in the canopy --the passenger had hit the inside hard enough to knock him out and smash out a big chunk of plexiglas after they hit a wave rotor on fast descent .

Another time at the same field a Hughes 300 did an autorotate and hit hard enough to cut off the tailboom ,detach the fuel tanks and, again, punch two head holes in the canopy --( I had previously encased the tanks in Kevlar as a precautionary AD and they did not split) -- loss of control in flight from contacting the canopy might be a real consideration and need some provision for restraint (or a little pad like Helmut Treiber made when flutter testing the SB9)

The ban on light unlimited racers because of hitting wake turbulence from the biggies is probably well based --even leg restraints are a good idea --kicking off a canopy at 500 MPH or so would not be a good thing (the same issue occurs with recumbent tricycles where you can 'run over your own legs' if you hit a bump and they contact the ground after coming off the pedals -- I built 'stirrups' into my recumbent Bicycle (no crossbar to trap the feet but still dangerous) after a near enactment of this. I had my feet come off the pedals when inverted in a Steen Skybolt and had bruised shins for weeks afterwards from hitting the fuel tank (when a passenger) --- the G regime of a racer is probably way beyond what average pilots are accustomed to . Bob probably recalls Dick Schreder inadvertently pulling the canopy release on a borrowed ASW 17 when flying in the US nationals --that has happened lots of times but highlights the need for extra provisions to lock (and jettison when needed) a canopy --and for bird strike at higher speeds very thick plexi or lexan would be a good idea .

Last edited: Mar 15, 2014
19. Mar 15, 2014

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Get span and area back to reasonable values. Even with a 100 sqft wing, it will only contribute to maybe 20% of your drag at zero G. It allows you to put a lot of systems in the wings (boil-off cooling). Single main gear is essential, since gear packaging becomes a biggie.

I'd have a good look at the Koenigsegg V8. Almost 1500 hp on stock bio-ethanol and a total running weight of around 400 lbs....

I don't see Aircar's issue with flutter. Even many sailplanes (AR<30) have flutter speeds of 400+ kts. I'd aim for the highest AR feasible, but something around 15 should be close to optimum. HM carbon fiber is pure magic...

20. Mar 15, 2014

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