A Peculiar Puffin

[Old Wombat]

Can't give a definitive answer but, generally, quite a bit - about 15-20 mph, from memory - but the big difference would be in the aircraft's combat handling. Spats, when flying at speed, cause downward drag which can severely reduce combat climb & turn rates & the weight of retracting gear is not necessarily that much heavier than spatted gear.



Guy

I think it was the Finn's who built a Fokker D XX1 with retractable undercarriage. Because of the extra weight involved with the retractable undercarriage It made no appreciable difference to the aircraft's performance so they converted it back. I'm only talking speed/climb etc. I've not read anything about the aircrafts manouverabilty.

It was quite a while ago (25/30 years?) but I remember reading about some early monoplane fighters which were initially built & tested with spatted gear, then fitted with the retractable gear they were designed for, which resulted in the above-mentioned improvements (but don't ask me when, where or which aircraft, because that info has been lost to time & re-purposed neurons). It is entirely possible that they may have been weighted to account for the later gear in the spatted stage, but I can't recall that info.



Guy

[Captain Canada]

Ooh I like it ! Looks just right. Like one of those aeroplanes I want to fly around the room....great job Chris !

[perttime]

Wikipedia figures (which might not be quite comparable) suggest that Miles M 20 might not have been too far behind Hawker Hurrine in speed.

More Wikipedia:
Avia B.35 (spats) gave 495 km/h (308 mph) while the B.135 (retracts) could do 535 km/h (332 mph).

Finnish Wikipedia has two paragraphs on the Fokker D.XXI with retracts.
Highlights (my translation):

FR-117 was converted 1940 - January 1941. Leading edge of the wing had to be modified, in addition to work on landing gear mounting and hydraulics. This conversion was not a success. The landing gear retracted too slowly and was not reliable. The hoped for 30-40 km/h speed increase did not materialize.

"Series IV" Fokker FR-167 was built with retracts from the beginning. It was completed by VL in March 1942. The retractable landing gear was a success on this aircraft. It reached 408 km/h on the deck and 423 km/h at 2800 meters, while a fixed landing gear "Wasp-Fokker" had only been clocked at 361,5 km/h at 2000 meters. FR-167 climbed better (13 m/s up to 3000 meters) and accelerated better in a dive than a fixed landing gear D.XXI.

One pair of the Wasp-Fokker's machine guns had to be moved from wings to fuselage - which the test pilots considered a great improvement. They thought that installing 12.7 mm machine guns on the fuselage and removing the wing machine guns would have made it better than Morane-Saulnier M.S. 406 which had been purchased for reconnaissance squadrons.

If there had been time for conversions, the rest of the "Series IV" aircraft would quite likely have been rebuilt with retracts.
http://fi.wikipedia.org/wiki/Fokker_D.XXI

[Mossie]

Found a snippet on the M.20 in the book on the Miles M.53 by Capt Eric Brown when evaluated it for the FAA.  He thought it wasn't as manouverable as the Wildcat, Hurricane or Spitfire and didn't offer enough of a speed increase over the Wildcat or Hurricane to give much advantage.  He wasn't sure it's use of wood construction would be up to carrier ops.  He was impressed by it's 12x.303 armament and reasonably impressed with the M.20 overall but especially taken by the timescale in which Miles could produce such an aircraft.

[Old Wombat]

Thanks, perttime!

Not where I read it (far too long ago for Wikipedia) but at least I now know I wasn't completely off with the nac mac Feegle (pictsies)!



Guy

[perttime]

Not where I read it (far too long ago for Wikipedia)

The W*** article refers to publication that are in Finnish only, as far as I know - but some books on Finnish WW2 gear are bilingual: Finnish, and Sorta English 

[Old Wombat]

I think the book was a generalised layman's book on aircraft design dating from the early-60's-ish era & didn't mention specific aircraft. Probably one of the $2000+ worth of books (calculated on purchase price) destroyed by water damage in 2001 (even then I don't think I'd read it for over a decade).



Guy