Air and space article about the DR1

[buck toenges]

Just got the latest issue of air and space magazine that states that the middle wing of the DR1 actually limit the lift of the airplane. The article states that "climbs like a monkey" wasn't due to the 3 wings. maneuverable yes lift no. Seems that the middle wing gets in the way of lift of the other two wings. How does the Dr1 compare to the DVI in regards to lift and maneuverability? The DVI with its DVII type thick wings vs the smaller DR1 wings?

[Laserlloyd]

Hi buck toenges:

I'm not the expert in this area but here is some information from Leon Bennett's book "Three Wings for the Red Baron" states that the British triplane had a poor L/D ratio of 6.1 with the middle wing L/D of only 2.7. The Fokker triplane had redesigned the airfoil along with the spacing and a different stager of the wings did improve this some but to answer one of your questions, yes the middle wing did have its draw-backs with the lower lift from the middle wing but it did gain better maneuverability in turns and climbs.

I'm sure there are better people here that can give more information, I just thought I start with some information...

Lloyd...

[Taz]

Buck- The article quotes Bennett's Three Wings for the Red Baron, which has quite a few technical errors in it. One is that the propeller on the early Dr.Is had a propeller more optimized for speed and less for climb and that this was changed later to one optimized for climb at the expense of speed. In fact all Fokker Triplanes from F.I 101/17 (the second Triplane) to Dr.I 598/17 used a propeller with the same 2.30 meter pitch. The three wings did not all contribute equally to lift, but they did contribute, as did the axle airfoil. The climb of the Dr.I can be attributed to light weight and large wing area with commensurate low wing loading, excellent airfoil design which generated high lift at all angles of attack, and a propeller which swept ~thirty percent of the wing area, providing extra lift. All those wings did, however create extra drag and the relatively low horsepower Le Rhone Jb and Oberursel Ur.II engines could not generate high aircraft speeds. The fastest Fokker Triplane, aside from the up-engined V.7s and other experimental Triplanes, was probably the original V.4, WN 1661, which had a smaller wing area and much poorer climb. The later Fokker D.VI with identical engine and only two wings with slightly less wing area than the Dr.I, provided roughly equal climb performance while being faster.

Taz
Terry Phillips

[Greybeard]

Originally Posted by Taz

The later Fokker D.VI with identical engine and only two wings with slightly less wing area than the Dr.I, provided roughly equal climb performance while being faster.

That's the demonstration, now the thesis: as a rule of thumb, CLIMB=POWER LOADING and TURN=WING LOADING (this latter should be better expressed as WINGSPAN LOADING).

Indeed, to climb is a matter of power, mainly, wingarea that's enough if being "adequate". A climber doesn't climb faster if his feet are bigger!

High lift of Dr.I, as mentioned, could help only to have better efficiency, if its aspect ratio would have been high enough. Unfortunately, not being so, its turning performance couldn't be much better than an A/C having same wingarea, distributed on only two wings.

GB

[Taz]

Greybeard- Power to weight ratio (power loading) is only part of the climb determinants unless a vertical take-off is used, as you said. The Fokker V.4, WN 1661 had superior power loading to the Fokker V.5, WN 1697, but climb was much worse due to insufficient wing area and the inability to maintain an optimum climb angle with the power (identical) available. You mentioned this in your post as needing adequate wing area.

Also, power is one of the determinants in turn rate, because while turning at increased angle of attack, drag increases dramatically and sufficient power is required or rapid deceleration results without reaching maximum turn rate. This is captured in modern aircraft by the term corner velocity, which is the lowest velocity (energy state) at which placard g can be reached with the power available. Examples are the low wing loading (lbs/sq foot) and high power loading (hp/lb) F-16 at 360 ktas and the now retired poor loading F-111F at 540 ktas. Below corner velocity, the aircraft cannot reach placard g.

Taz
Terry Phillips

[Greybeard]

Taz,

I agree, of course, and I'm sorry if failed to make myself understood.

I meant those two as *coarse* rules; that's to say main factors, not the sole.

In case of Dr.I it had, in my opinion, neither a good aspect ratio nor enough power to be *really* a "monkey".

BTW, what is "placard g"?

S!
GB

[Barrett]

This article seems way peculiar in that it describes the Fokker D.VII as a sesquiplane. IMO it does not remotely fit the usual interpretation (bottom wing much smaller chord than the top). Certainly the D.VII fails the Albatros D.III/Nieuport Scout comparison.

[FlyXwire]

Barrett,

According to the article THE SESQUIPLANES by D.H.R. White, the term sesquiplane strictly interpreted means "a biplane aeroplane having one pair of wings, - usually the lower, - of half the area of the other pair."

In this sense, the Albatros V-Strutters probably couldn't have been considered sesquiplanes, however White subsequently (and more simply) defines "sesquiplanes" as "a biplane having lower wings of distinctive less area than the upper ones."

I have not read the Air & Space article this discussion is referring to, but I certainly plan on buying this issue.

[Barrett]

Dave, save your money. Here 'tis.

What the Red Baron Never Knew

"Irregardless" of the Sesquiplane definition, just ain't no way the D.VII qualifies, nohow.

[FlyXwire]

Thanks loads Barrett!

Here's the URL to the sesquiplanes article (in PDF file format), but the site doesn't allow "hotlinking", so you'll need to copy and paste this address directly into your browser to access it:

http://asww1ah.0catch.com/Sesquiplanes.pdf