Chill31

It depends on the aircraft. For example, the Albatross series and SPAD have one continuous spar through the top wing. Others, like the Camel, have segmented top wings, and the flying wires (as opposed to the landing wires) prevent the wings from folding up. All of the wire braced aircraft derive some/most(?) of their strength from the wires.

My maximum speed, full throttle is about 160 kmh with the 80 Le Rhone on it. (I am going to test it again using my video footage of the GPS though.) Based on my calculations, the Dr.I with 120 Hp Le Rhone, should go 175-180 kmh.

Here are some initial C++ simulation results for a Dr1 at 757 Kg, 79 hp assumed at an altitude of 3000 ft STD at 15 deg C (I don’t know how much the Le Rhone loses with altitude from 85 hp at SL but I’ve assumed 79 hp at 3000 ft STD): Max momentaneous turn at Clmax starting off at 85 mph IAS keeping altitude but letting speed drop: 13.5 s to do a 360 deg turn. Rough estimates based on the max initial turn rate at 85 mph IAS when entering turn for a 360 degree turn keeping speed up by dropping in altitude: circa 7.2 s. Stationary turn time at 55 mph IAS keeping altitude: 18.5 s to do a 360 degree turn. In the video I posted, you can time the turns to see how long they take. I started out very aggressive and backed off until I made level turns and held altitude And did not stall. I think I timed it at 10 seconds. BTW: I found the text below on the Aerodrome forum by someone with the handle baldeagle which includes rolling in and out of the turn in a “Triplane” (I’m assuming a Dr1?) indicating I’m currently a bit pessimistic in my 18.5 estimate which does not include that: “By the way, be careful where you get your numbers from, the last Triplane I flew I timed a 360 degree turn, from level to level again, so including rolling in and rolling out, and it was almost 20 seconds, even with Voss and a rotary engine it isn't going to be much less, certainly not anywhere near 5 seconds. Those figures you get from 1917 are measured by very uncertain means, not to mention the exaggerations made by manufacturers, pilots, and anybody with a point to make. I wouldn't put too much stock in contemporary figures, except in very general terms.” Any thoughts on baldeagle’s comment above? My power off stall is around 45 mph. Power on, it is much lower, maybe 30 mph? I will have to do some detailed tests. 18.5 seconds seems like a long time, so does 20 with roll in and out. Look at my video to see how long it takes to roll in and out. I have not timed that yet. I’m not sure what the 5 second referencing, but it would be about right for 180 degrees of turn. You may have just a little too much drag built in to your model?

Before breaking? I think with more speed, I could definitely tap 7Gs. Considering the load testing I read about previously and how it handles 4 Gs, 7 is likely a reasonable maximum. This is a complete guess however

I am reviving this thread, since it was my intent for it to be all things Dr.I related for the FC forum... Arising from the DM thread, I did some testing of the Fokker Dr.I, now powered by a 1917 80 hp Le Rhone, incorporating a G-meter and a modern GPS unit to give a speed reference (note: GPS speed is not airspeed and serves only as a general reference in this case). I had several questions going into this flight. 1.) How many Gs am I pulling through loops, fast turns, and sustained turns? 2.) Can I make it flip out like the FC Dr.I during any accelerated stall generated by turning? 3) Can I make it flip out by simply being nose high and stalling? Before I found the answer to #1, I thought I was pulling 2-2.5 Gs during a loop. The stick forces per G are VERY light in the Dr.I, the lightest of any aircraft I've flown. Based on the seat of my pants and the stick forces, I thought the G forces were very low and questioned how it would be possible to pull 5 Gs like we do in FC. What I found was that I hit 4-4.5 Gs during the initial pull on a loop, about .3 Gs inverted, and about 3 Gs coming down the back side of the loop. I was shocked to find this out. Sure, the math says it must be this way, BUT it feels so easy and effortless, I almost fell out of the plane from surprise. I also did some defensive turns to the left and right. Again, I was amazed that I was hitting 3+ Gs in the turn while trying to stay level. To answer #2, I did right and left turns while trying to stay level and hit a stall. To the right, the airplane gently rolls to the inside of the turn. I can stop it easily by unloading a little back stick force and then continuing the turn. To the left, it was gentle as well. However, the gyroscopic effects of the engine seemed to keep it from rolling into the turn. Instead, I seemed to fall sideways. I need to do a little more testing on the accelerated stalls to the left, since I cut my flight short as the sun went down. In each case, it was a DEFINITE departure from the FC Dr.I behavior. In FC, the Dr.I spins readily, and does wild gyrations when you try to turn left or stall while turning left. This behavior is not supported by any of the flight testing I have done so far, and I would urge a FM review in this area. For #3, I pulled the nose up into a climbing left hand turn and continue the turn until I stalled. All of these maneuvers were done with power on, 75% or more. Here is the video of the highlights, note at about 1 minute in, the engine quits from maneuvering, something I have never experienced in ROF/FC.

I got to fly the Dr1 today. The short version, the G forces in FC are correct. I had no idea! Easiest 4 Gs I've ever pulled...I'll post video and information in a new thread for discussion so I don't dilute this one any further.

This video shows a 360 turn at about 2:15. It is a max turn with no effort to maintain altitude, but I did try to avoid a stall. Looks like about 8 seconds.

That weight is about right. I am at 575 or less when I fly my Dr1. The 80 Rhone currently running on my Dr1 is probably giving me 85 hp because it has aluminum pistons. I don't know the answer on the G limit question. I think 6.5, maybe 7, is the max the wing can take. My intent was to do G testing out to 4 Gs, but I never pursued it very hard as I never felt more than 2.5 Gs in any of my maneuvers. I flew on the Flugpark tonight and got in a nice scrap with several Camels while flying the Dr1. I shot two Camels quite a lot. One guy flew well, and managed to disengage with his wings all shot up (graphic depicted his struts shot away with big holes in the wing). The other guy fought on with wing damage depicted at a lower level than the first Camel. He did a diving turn and the damaged wings came off first. He must have been at quite high Gs though. So far, I'm not seeing anything that doesn't seem realistic other than my turns at 4.5 Gs, but i am still waiting to test the real plane.

About 6 G maximum is also in line with the testing i reported earlier for the Dr1. The thing that raises my eyebrows is the ease with which I attain those Gs in the Dr1 when I do the exact same maneuvers in the real plane, yet the G force feels like much less. Alas, it is raining here for the 3rd consecutive day, so probably no testing today.

These values are what I expect to see in the DrI. http://naca.central.cranfield.ac.uk/reports/arc/rm/469.pdf

There are many edges! So I suppose it depends on which edge you have in mind. Speed...I've hit 140 mph in a dive. G-loading...I have yet to measure it, but based on feel, maybe 2.5Gs. Aerobatic manuevers...I have done them all as much as I can. I don't do "snap" or "flick" maneuvers though. They really aren't suitable for the Dr.I. The FC Dr.I does them readily, however, the real Dr.I does not stall easily enough to do them. It would wallow around the sky if I tried. I think the Dr.I is good for 4-5 Gs reliably. Probably 165 mph (before the engine begins to overspeed). You can see how much room I have left by comparing the numbers, so maybe 6 or 7?

No doubt! Planning a head mounted go pro with the G meter in view and a rear facing go pro to see the tail surfaces.