A few people here observed that a guncutter (per Into the Storm) is quite close to Thunderhawk.

Now, a side by side comparison:

It's indeed the same hull. They didn't even move those twin-linked heavy bolters. Now we can try to figure out what's inside :

Thunderhawk's cruising speed is not given in RoB, but in BFG has speed 20cm, just like Starhawk. Both Fury and Shark are 30cm, and they are still equal in RT. Thus 6VU. Guncutter has 5. However guncutter has greater endurance (for interplanetary flight, rather than shuttle), at least in the variant with cabins.

Thus the differences are:

1. Lack of the turret.
2. Engines are somewhat weaker and not so hot in afterburner and vector thrust department; possibly adapted from other small craft.
3. Nose is redesigned - no front ramp; streamlined for atmospheric flight and using different armor.
4. Back cabin/upper hold are slightly changed - part of it may be different armor, but the long upper plate goes further. Possibly it's extended (taking that "loft" of upper hold) to include extra stations for Enginseer and second gunner.
5. Aft side of the forward hold is different, too (instead of a plain slope, half slope and box).
6. I don't see autocannons instead of lascannons, or anywhere. Maybe it's because the wing is not lowered all the way? Unless its barrel is that bar extending above the door, in which case it's above the non-folding part of the wing, behind the engine.

Unless the cannon is right on the hull, reloading or changing ammunition in flight may be troublesome. A magazine selector can mitigate this problem. Installing a weapon on top of equipment compartment (instead of the turret) may be possible too. A weapon installed right on the hull could be reloaded, though this would probably require a mini-airlock with servo manipulators. Return to Thunderhawk configuration with lascannons on the wing arms and either autocannons/multilasers (for softer ground targets) or long-range missiles (vs. other void/air craft) under wings may be a better idea.

It's reasonable to assume that holds contain extra lifesupport and supplies, while aft compartment instead of various parts plugged into the turret has more fuel and propellant.

I like that cutter more than the regular flying metal bawkes.

Yeah, it's cool. It just occurred to me that it could be better and easier to start with Thunderhawk Transporter, however.

Easier because — just drop clamping arms and armor on the lower "waist", add some hatches on the cabin and rear compartment, then attach a single long box as the whole lower fuselage. No need to change the nose or anything else.

Better, because the commercial version instead of 3 inferior engines would have 4 inferior engines. And because it would be wonderfully modular - armed shuttle, armored flying scanner, close air support, tank hunter, bomber or interceptor would require very few changes beyond, er, "mission gondola" and equipment on external hardpoints. Relevant extra crew (e.g. navigator's station for long travel or gunner seats for as many guns as on Stormbird ) can be built into the gondola too. And even adding power field generators probably won't be too tricky, now that equipment pointing to all sides can be made accessible from the inside.

On ‎21‎/‎03‎/‎2018 at 9:09 PM, TBeholder said:

Unless the cannon is right on the hull, reloading or changing ammunition in flight may be troublesome. A magazine selector can mitigate this problem. Installing a weapon on top of equipment compartment (instead of the turret) may be possible too. A weapon installed right on the hull could be reloaded, though this would probably require a mini-airlock with servo manipulators.

I always assumed there were guns mounted in the nose. That pointy nose doesn't look like an access door, and it's replacing an assault ramp capable of deploying astartes in tactical dreadnought warplate, so a centreline weapon or two isn't unreasonable.

On 4/9/2018 at 1:50 PM, Magnus Grendel said:

I always assumed there were guns mounted in the nose. That pointy nose doesn't look like an access door, and it's replacing an assault ramp capable of deploying astartes in tactical dreadnought warplate, so a centreline weapon or two isn't unreasonable.

It could be stuck there, but long-barreled autocannons are supposed to be much larger than heavy bolter, no? They'd be fixed, and still take most of the lower hold. Also, if stuck together, that would be 1x twin-linked autocannon, rather than 2x single.

If not autocannons, the nose may contain some equipment moved from rear compartment (where it's replaced with larger tanks). Or just a more streamlined nose tip desirable due to weaker engines.