The Gorgeous XB-38
- Thread starter MIflyer
- Start date
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SaparotRob
Unter Gemeine Geschwader Murmeltier XIII
Decades ago I got into a fight with my then girlfriend because of this plane. We were having a pleasant drive. I was lost in thought. She asked: "What are you thinking about?"
"What would a B-17 look like with Rolls-Royce Merlin engines?" I replied in my innocence.
When women say they want honesty, they lie.
"What would a B-17 look like with Rolls-Royce Merlin engines?" I replied in my innocence.
When women say they want honesty, they lie.
- Thread starter
- #3
MIflyer
1st Lieutenant
The XB-38 was faster than a B-17E. I think one in the YB-40 "fighter" configuration would be very beautiful.
GreenKnight121
Senior Airman
- 598
- Mar 16, 2014
Not Merlins... Allison V-1710-89 engines.
The XB-38 delivered a higher top speed, but its ceiling was lower. After a few flights it was grounded due to exhaust gas leaks from the engine manifolds. Once this had been fixed, testing resumed until the ninth flight on June 16, 1943 when the inboard starboard engine caught fire and the crew bailed out. The XB-38 was destroyed and the project was canceled, in part because the V-1710 engines were in high demand for P-38, P-39, & P-40 fighters (by mid-1943 the P-51 was only produced with Packard Merlins).
XB-38:
max speed 327 mph (526 km/h, 284 kn) at 25,000 ft (7,600 m)
cruising speed 226 mph (364 km/h, 197 kn)
service ceiling 29,600 ft (9,020 m)
B-17F (type in production in June 1943):
max speed 299 mph* (481 km/h, 261 kn)
cruising speed 200 mph (322 km/h, 176 kn)
service ceiling 37,500 feet
* 325 mph War Emergency Power for short periods
The XB-38 delivered a higher top speed, but its ceiling was lower. After a few flights it was grounded due to exhaust gas leaks from the engine manifolds. Once this had been fixed, testing resumed until the ninth flight on June 16, 1943 when the inboard starboard engine caught fire and the crew bailed out. The XB-38 was destroyed and the project was canceled, in part because the V-1710 engines were in high demand for P-38, P-39, & P-40 fighters (by mid-1943 the P-51 was only produced with Packard Merlins).
XB-38:
max speed 327 mph (526 km/h, 284 kn) at 25,000 ft (7,600 m)
cruising speed 226 mph (364 km/h, 197 kn)
service ceiling 29,600 ft (9,020 m)
B-17F (type in production in June 1943):
max speed 299 mph* (481 km/h, 261 kn)
cruising speed 200 mph (322 km/h, 176 kn)
service ceiling 37,500 feet
* 325 mph War Emergency Power for short periods
SaparotRob
Unter Gemeine Geschwader Murmeltier XIII
I have long ago learned they were Allisons. However, at that time, she asked me what I was thinking about. I made the B-17 / Merlin statement. I just want to be honest.
special ed
1st Sergeant
- 4,858
- May 13, 2018
They also do NOT want to be "just one of the boys". Ask me how I know.
- Thread starter
- #7
MIflyer
1st Lieutenant
A recent interview revealed that that some also do not want their boyfriends to be "one of the boys" either. Don't ask me what that means.
- Thread starter
- #8
MIflyer
1st Lieutenant
When the early models of the P-38 came out they had a problem with the turbos overspeeding at high altitudes and that is where the shield to protect the pilot from the turbos exploding came from. They corrected that by increasing the boost out of the engine driven supercharger by changing the gear ratios and they probably could have upped the boost on the XB-38 the same way. Aside from that, they no doubt used the original air-to-air intercoolers inside the wings. If they had switched to use air-to-liquid intercoolers such as the Merlin Mustang employed they likely could have reduced drag.
And after the XB-38 came the XB-39 with V-3420's.
wuzak
Captain
The intercoolers were in the chin of the nacelle, like a P-38J.
The coolant radiators were in the leading edges of the wings, between the nacelles.
GrumpyOldCrewChief
Airman 1st Class
Anybody aware of any sort of conversion set for this? In 1/72nd?
Yes, I make a 1/72 conversion for the XB-39. It consists of two full outer nacelles, two shorter inner cowlings to attach the inner kit nacelles, and four spinners. I usually have them for sale on ebay but I'm one cowling short right now. I haven't been doing any casting recently - too busy actually building for a change! 
For the inner nacelles you only need to front part (hash marks show what to remove). Then you need to fair the cowlings into the existing inner nacelles, which include the landing gear bays. Note that the B-29 (and XB-39) cowlings are aligned normal to the wing. They are not vertical relative to the ground. Academy got that detail wrong.
For the inner nacelles you only need to front part (hash marks show what to remove). Then you need to fair the cowlings into the existing inner nacelles, which include the landing gear bays. Note that the B-29 (and XB-39) cowlings are aligned normal to the wing. They are not vertical relative to the ground. Academy got that detail wrong.
I have purchased a few updates from you my friend. Good stuff!
Skyediamonds
Staff Sergeant
- 1,082
- May 26, 2018
Tbird:
I just read your post with interest. Can you clarify what is meant by aligning the nacelles vertically?
I just read your post with interest. Can you clarify what is meant by aligning the nacelles vertically?
- Thread starter
- #15
MIflyer
1st Lieutenant
He means that the engine Nacelles are at right angles to the Wing, not aligned so to be parallel with a vertical line coming up 90 degrees to the ground. The dihedral of the wing makes the difference.
Skyediamonds
Staff Sergeant
- 1,082
- May 26, 2018
Ahhh that's really interesting. Very few aircraft go against the general concept. Junkers Ju-52 for example, has its engines mounted to perpendicular to the leading edges of the wing, rather than parallel to the line of flight.
I bet the front view of the XB-39 really makes for an intriguing shot.
Thank you for your reply.
Slightly shifting gears but related to the topic of conversion of models; I hope to model the Guillow's P-38J kit into the original prototype XP-38. Just love the highly polished aluminum finish & unique radiator cooling retractable vents mounted on top of the booms, the top of the canopy hinges on the right side, no elevator bullet shaped balance horns & more.
What I haven't let known is I also have several Guillow's kits of the B-17 & -29; both of which I'd like to model differently from the run-of-the-mill kits. The Guillow's B-17G to be modified into a YB-17 "Swoosh." Just something about its all-highly polished finish with the unique features of a slim rear fuselage, swoosh tail, unique side blisters, double bubble nose & more.
Another possibility is the B-17 used as Model 299 testbed for the huge Wright Turboprop Typhoon in its nose.
I realize you might be thinking of Guillow's as a skeletal frame wrapped in tissue & either rubber or electric powered. I infilled & plank the fuselage & wings followed by covering with aluminum foil.
I've posted several step-by-step builds of my Guillow's Mustang on this site.
Thanks again,
Skye
SaparotRob
Unter Gemeine Geschwader Murmeltier XIII
I loves me my shark tails. I'd love to see the 299.
Skyediamonds
Staff Sergeant
- 1,082
- May 26, 2018
Saparo:
So would I….. I've been modeling for over 65+ years & I've seen all manners & sizes of B-17's & I've yet to see anyone model that testbed.
Maybe there are a few plastic early YB-17s, but none that I'm aware of in the larger scales.
Skye, I think you may have misunderstood the comment about the B-29 engine alignment. When viewed from above, the nacelles are indeed aligned with the direction of flight, like almost all aircraft. Like you said, the Ju52 was an oddball, having the engines pointed outwards, perpendicular to the leading edge sweep angle. Strangely, the Fw200 outer engines were also pointed outwards.
The point I was making about the B-29 and XB-39 is that when viewed from the front, the oval-shaped nacelles are not oriented vertically relative to the ground. They are tilted by the amount of the wing dihedral. The 1/72 Academy B-29 model orients the nacelles vertically, so it is incorrect. Not all that noticeable on a B-29. I had to go look at a real B-29 to convince myself about this as it was kind of hard to tell in photos. It is far more obvious on the XB-39 with those huge nacelles, however. The great thing about this from a modeling perspective (and maybe for the Boeing engineers who designed the B-29) is that it makes the port and starboard sides more similar.
The point I was making about the B-29 and XB-39 is that when viewed from the front, the oval-shaped nacelles are not oriented vertically relative to the ground. They are tilted by the amount of the wing dihedral. The 1/72 Academy B-29 model orients the nacelles vertically, so it is incorrect. Not all that noticeable on a B-29. I had to go look at a real B-29 to convince myself about this as it was kind of hard to tell in photos. It is far more obvious on the XB-39 with those huge nacelles, however. The great thing about this from a modeling perspective (and maybe for the Boeing engineers who designed the B-29) is that it makes the port and starboard sides more similar.
Skyediamonds
Staff Sergeant
- 1,082
- May 26, 2018
Tbird:
I fully understood what you meant. I was only using the Ju-52 as a ( now ) poor analogy to illustrate the mounting of engines on the XB-39 was contrary to the norms of other multi engined aircraft as unusual as it is, was not an isolated aircraft but shared its uniqueness with the Boeing.
At the moment, the Junkers was the only aircraft I could think of off the top of my head. Whereas the XB-39 alignment is vertical, my poor comparison was lateral.
You're correct about the vertical alignment of the nacelles of the XB-39 with respect to the wing dihedral rather than perpendicular to the ground as other aircraft. It gets crazy when we can't actually engage in vis-a-vis conversation but instead, rely on texted words.
Just as yourself, I had the opportunity of seeing a real B-29 up close & personal (Fifi) during a special airshow held in San Diego, Calif. many years ago. Truly a giant aircraft of its day.
