Like a Lotus 7 with a LS Swap

"CaptDale - is secretly British" (captdale) 02/21/2019 at 18:15 • Filed to: Planelopnik, Learjet

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I have mentioned here before I want a Learjet. Not just any Learjet, but specifically a !!!error: Indecipherable SUB-paragraph formatting!!! . For a cool $300,000 you can fly in the most luxurious and amazing planes the 60/70's had to offer.

Sadly with the move from Turbojets to more quiet and efficient Turbofans, the old CJ610 was just too noisy for the US government to allow to fly here without the dumb Hush kits.

Let me tell you if you haven’t heard an un-hushed turbojet taking off, you are missing out on one of the best noises on earth. But they are loud and they are definitely no very fuel efficient. With takeoff the LJ24 uses about half its fuel in the first hour because thirsty boy.

So I always thought if I had “fuck you” money I would pay all the fee and fill out all the forms to upgrade the jets to more modern turbofans. BUt which ones would I go with? Well today ladies and germs I have figured that out.

I thought it best to keep things loosely in the family and pull the jets off a Bomedier (owns Learjet) 605. That means the General Electric CF-34B.

Let us do some comparisons:

OE equipped GE CJ610

Length: 45.4–51.1 in (1.15–1.30 m) (depending on accessory equipment installed)

Dry weight: 396–421 lb (180–191 kg) (depending on accessory equipment installed)

Performance

Maximum thrust: 2,850–3,100 lbf (12.7–13.8 kN) at sea level

Specific fuel consumption: 0.96 - 0.97 lb/(lbf·hr)

Now the GE CF34

Length: 103 in (2.6 m)

Diameter: 49 in (1.2 m)

Dry weight: 1,670 lb (760 kg)

Performance

Maximum thrust: 9,220 lbf (41.0 kN) at sea level

Specific fuel consumption: 0.69 lb/(lbf·hr)

So roughly add 2000 lbs of weight for almost 5 times the thrust

update: made a mistake calculating with the power from only one engine

With the CJ610 power to weight is .22  .443

With the CF34 it is . 69  1.366

Though unless I could also raise the max take off weight from 13500 to 15500 then I lose 2k lbs of cargo capacity.

But I might be ok with that for 3 time the power to weight. Talk about unrestricted climb.

*yes I know I am crazy*

ttyymmnn > CaptDale - is secretly British 02/21/2019 at 18:22

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The hush kit never really went away completely. It’s just a lot prettier now.

way2blu does a rev update > CaptDale - is secretly British 02/21/2019 at 18:22

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That’s a lot of weight carried really far back, aren’t you worried it’ll snap-oversteer if you let off the throttle while cornering?

farscythe - makin da cawfee! > CaptDale - is secretly British 02/21/2019 at 18:22

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would the frame survive all that extra thrust?

coz.... to much power for the frame is a problem in a car... i reckons it might be a little more than a problem in a plane

HammerheadFistpunch > CaptDale - is secretly British 02/21/2019 at 18:23

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I had a feeling you were going to say cf34.  

CaptDale - is secretly British > way2blu does a rev update 02/21/2019 at 18:29

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V8 swap the MR2 and let me know

CaptDale - is secretly British > farscythe - makin da cawfee! 02/21/2019 at 18:29

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Well that would be studied if I had the money

CaptDale - is secretly British > ttyymmnn 02/21/2019 at 18:29

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Yeah I know, but huuuusssshhhh

CaptDale - is secretly British > HammerheadFistpunch 02/21/2019 at 18:30

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*finger guns*

way2blu does a rev update > CaptDale - is secretly British 02/21/2019 at 18:32

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I’ll need a Subaru WRX STI transmission so I can mount the whole thing backwards, but I think it’s doable. CARB-compliant too with the E-Rod LS3...

farscythe - makin da cawfee! > CaptDale - is secretly British 02/21/2019 at 18:32

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righto

carry on then

CaptDale - is secretly British > farscythe - makin da cawfee! 02/21/2019 at 18:39

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*penny for the poor*

But yeah the FAA has a lot of guidelines on recertification of a plane for whatever modifications you are doing. Especially power plant

Turbineguy: Nom de Zoom > CaptDale - is secretly British 02/21/2019 at 18:45

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Didn’t we discuss this already? If you wanna repower a Jurassic Jet like a Lear 24, the Williams FJ44 is the only way to go. Similar thrust & weight but much more efficient and MUCH quieter.

CaptDale - is secretly British > Turbineguy: Nom de Zoom 02/21/2019 at 18:48

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No I don’t recall that and I don’t care about quieter. If that was the case I would keep the hush kits. I want MOAR POWER

CaptDale - is secretly British > way2blu does a rev update 02/21/2019 at 18:48

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Of register not in CA and get more power? You could also use a Cadillac FWD trans

Turbineguy: Nom de Zoom > CaptDale - is secretly British 02/21/2019 at 18:52

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Seeing as the CF34 is a turbofan it’ll be much quieter than the straight-pipe CJ610. And MOAR POWER doesn’t work too well in aircraft not designed for it. But if you want to hang a pair of CF34s (at 4x the weight) on a small Lear, ya better put a tailwheel on it because it’ll be dragging its butt down the runway in a shower of sparks. Actually, that would be pretty impressive..

CaptDale - is secretly British > Turbineguy: Nom de Zoom 02/21/2019 at 18:55

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Yeah I am sure something in between the CJ610/FJ44 and the CF34 would honestly be a better bet, but come on. Who doesn’t like the idea of a LS in a Lotus 7?

Tail wheel would interesting on there for sure.

Turbineguy: Nom de Zoom > CaptDale - is secretly British 02/21/2019 at 18:57

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Tail wheel would interesting on there for sure

You’d have the only one.

CaptDale - is secretly British > Turbineguy: Nom de Zoom 02/21/2019 at 19:00

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I like having the only one XD. But I think I would end up needing Warren Buffett money. So sadly might just need to stick with a standard LJ24. Not like those things aren’t hot rods to begin with. 

WilliamsSW > CaptDale - is secretly British 02/21/2019 at 19:42

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Feels to me like this swap would give you an airplane that’s a nightmare at the stall.

Also, more power with no other changes will make takeoff more fun but probsbly * won’t* get you that much more speed.

Speeds are more closely linked to wing design than power.

CaptDale - is secretly British > WilliamsSW 02/21/2019 at 19:50

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Shhh out of here with you semantics . 

WilliamsSW > CaptDale - is secretly British 02/21/2019 at 22:03

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I’d go with something roomier - the Queen of the Skies.

Or Ed Force One

CaptDale - is secretly British > WilliamsSW 02/21/2019 at 22:12

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Naw that’s nothing I’d want to fly for my own personal plane. I want a hot rod of the skies!

Jayhawk Jake > CaptDale - is secretly British 02/22/2019 at 09:45

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It’d be a cool way to commit suicide I guess?

Nothing about that swap would actually work. 

CaptDale - is secretly British > Jayhawk Jake 02/22/2019 at 10:37

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I know, but big dreams etc lol

CaptDale - is secretly British > Turbineguy: Nom de Zoom 02/23/2019 at 16:04

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I wonder if the P&W PW535E would be a more suitable swap

Roughly the same size and the CJ610 but with twice the thrust and weight only 800 lbs    

Turbineguy: Nom de Zoom > CaptDale - is secretly British 02/23/2019 at 18:19

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Nooop. That extra 800lb on the back of a light jet like the Lear 24 would make it impossible to trim out. The test flight would be its first & only time off the ground. The Williams FJ44 is the best fit; next would be Pratt Canada’s JT15D series.