SAAB J-21R Question

[Arc3371]

How complicated would it be to replace the engine with a BMW 003/ATAR engine?

[jcf]

Goblin (second series J-21RB used Goblin III with 1,500 kg thrust)
Length: 2.55m (100.40 in)
Diameter: 1.27 m (50.00 in)
Thrust: 1,365 kg (3,009 lbs)

BMW 109-003A-1(production engine, ATAR 101 V1 similar with doubled thrust)
Length: 3.565m (140.35 in)
Diameter: .69 m (27.17 in)
Thrust: 800 kg (1,763.70 lbs)

ATAR 101 C (first production series)
Length: 3.68m (144.88 in)
Diameter: .89 m (35.04 in)
Thrust: 2,800 kg (6,173.00 lbs)

Aside from the obvious differences in length and diameter, the engine accessories and drive are located in completely different areas between the Goblin and BMW, the ATAR used an extension drive to a remote accessories drive.

As you can see from the under construction photos, space was at a premium in the J-21R.

Jon

[Arc3371]

Thanks for the answer and pics

[jcf]

You're welcome.

Oddly enough if one was to re-engine the J 21R the better solution would be an engine with less power than the Goblin.
The top speed of the J 21R was almost the same as the airframe Critical Mach number, a slight nose down at high engine speed
caused the aircraft to quickly over-speed producing the expected compressibility effects and providing an exciting ride for the pilot.
This sensitivity limited the vertical plane combat maneuverability of the aircraft in the air-to-air fighter role and, along with the limited endurance (40 min) caused by low fuel capacity, is one of the main reasons the aircraft was moved to the attack role.

Prior to the jet conversion other developments of the J 21 were worked on, the J 21B design featured a bubble canopy and cut-down dorsal engine cover... Packard Merlin/DB605 piston powered and and Svenska Flygmotor or STAL turbojet powered versions were worked on.

Justo Miranda posted a SAAB concept pic on Secret Projects that I think may be one of the turbojet J 21B concepts, I've included his pic.

Back to J 21R re-engining, I'm thinking maybe a pusher turbo-prop?

Jon

[Arc3371]

How about a A.S Python turboprop?

[jcf]

How about a A.S Python turboprop?

Too big, its even larger than the Ghost, and the flow setup wouldn't work.
Actually, none of the big period turbo-props would work in a direct pusher setup in a small airframe.

Metrovick built and tested the aft-fan "thrust augmentator" F.3 turbo-fan, so take that basic notion but have it drive contra-props instead of a fan?
Maybe?

Jon

[tinlail]

A ducted fan like the OPTICA OA7 ?