Any plans for a nice turbine upgrade?
Not many people know that many of Richtofen's victories were in an Albatross. And in 1917 the Germans molded the laminated plywood fuselage skins in a heated pressurized concrete mold. Something that Jack Northrop did 10 years later with his first " Lockheed" design, a beautiful little biplane before the Vega series that also used the mold technique and today we tout the advent of molded composite structures. Nothing new. An Albatross with an upright Ranger in it would be fun. Better yet with a 180 HP BMW 111A. Anyway, it's wonderful that there are those who return to the roots of aviation be it military or otherwise. Switches
Koloman Mayerhofer is building a German version of the Albatros DIII, all original with an original engine. It's amazing what near unlimited resources can do! Just a brilliant construction. Image Unavailable, Please Login
I may be incorrect re the construction of ALL the Albatross airplane fuselages but I DO believe that the D-V and D-VI were made in concrete molds and inflated bags. Incredibly beautiful examples that Mayerhofer is building of the D-III. Thanks for posting. Switches
Folks following this thread may remember the SAE#1 prop hub retainer that was done in the WW1 style of some Camels to avoid the look of the stock Rotec plain retaining washer. Here is a view of it on the 90" prop. I have another being antique brass plated for another option, just for bling if it looks good. Thanks to a friend building a Pup, the prop will also have Admiralty Design or Integral manufacturer decals. I suppose we could do a Lang, which are pretty,but they only put them on one side and that looks unbalanced. Some of you may also remember the use of Aeronca Champ heel brake pedals. The position may initially seem unusual, and it is, but they are placed very specifically for two circumstances while allowing comfortable use of the rudder bar. The first is to hold the plane at start up, or to stop the plane at very low speed. The other is to allow use of the pedal at full throw of the bar on the same side. It looks weird, I know. The bar does swing well clear high over the small pedals. There is a below the floor shot showing the bracketry and adjusters, The pedal floor holes will be dressed with slotted leather patches. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
The brake pedal set up looks proper logical and workable to me but then I have flown some machines with the same set up. It works with a rudder bar or pedals. This is going to be SO much fun. Switches
Russ, With a 90 inch prop, how fast are you going to spin the engine, and what power does the engine make at that speed?
An excellent topic. The Rotec R-3600 engine (3.6 liters) is rated at 150 hp at 3600 rpm, which is translated through a 3:2 reduction to 2400 rpm. Cruise rating, (around 75%) is 1900 - 2100 prop rpm. The propeller is a 90 x 48. At a 75% power (110 hp) cruise of, let's say 2000 prop rpm, the tip speed is about .71 mach, or 786 ft/sec, for a no-slip forward speed of 90 mph. It's important to keep tip speeds less than 75%-80% Mach (tell that to a T-6 guy). I think this is more a climb prop, and I may later pitch it up to 50". The goal is an 85 mph cruise - all above is gravy. If I can take a bigger bite without killing climb carrying my heavy bottom in such a draggy 1200 (max 1319) pound flying machine, the dream would be a 90 mph cruise.
Russ- A Fokker Dr.I prop was 2.62 meters (103 in) in diameter and had a pitch of 2.30 meters (91") and really was a climb prop, but the engine only turned 1200 rpm or so, like a LeRhone Camel. Your prop is turning at nearly twice the speed, so your pitch number looks about right, but could be higher, as you have computed. Two seater aircraft of the same period had much lower propeller pitch numbers, in the 1.7 meter region, and had poorer climb characteristics, as you would expect considering their P/W. A good portion of the lift and control authority from WW-I aircraft, especially the single seaters, came from wind blast from the propeller over the wing and control surfaces, except for the ailerons. Yours will be moving quite a bit of air, so expect the tail to be flyable after an amazingly short period of time with good pitch and yaw control, but with roll kind of sluggish until a bit later and more velocity. One of the reasons cross-wind take-offs or landings could be problematic. Roll control was relatively poor at low speeds, made worse by the swirling pattern of the air from the large propellers, which tended to impart its own roll moment. Taz Terry Phillips
Taz - excellent discussion - I am learning more every day. Many thanks! I've been somewhat steered by experience of previous folks with their propellers and engines. The most referable example, Blake's 110hp Rotec N28 (same rpm ranges), has a 79x47 prop and cruises at about 80 mph. The F.1 has a slightly larger frontal area (43 vs 38" dia) and more wing area than the N28, but a thinner wing and uses streamlined RAF wires as opposed to draggy round (and accurate) cables on the Nieuport. The Sopwith carries a much larger prop disc (44 sq ft vs 34 sq ft), but also more hp. Depending on weather, Blake statics 2900 - 3100 engine rpm (1933 - 2066 prop rpm) and cruises about 85 at 3100 engine rpm. I suppose the Sopwith replica would be faster if the propeller was a bit shorter with more bite, but we'll start off here. Much less than 90" and the propeller begins looking a bit out of place. Important editorial comment: Speed is a nice to have, but not a driving reason for building this aircraft. The original Camel cruised about 100 mph back in the day. If I wanted speed I would have gotten an RV.
A couple of questions: With the tank up front, do you have to worry about CG changes as the fuel level changes? Or is it going to be heavy enough forward even when empty? Second, is the heel brake setup your idea, or the builder's, or a collaboration? I'm just curious if this is standard (if such a word applies!) updates to the WW1 designs for recreations? :bowing: (we're not worthy) etc...
The tank is very close to the desired CG, so the weight change is not as much noticed in the balance as it is the weight. In replicas, anything goes as far as the brakes, everything from hydraulic discs on pedals to the original no brakes at all. In a modern world, you do need some kind of brakes unless you have your own wing walkers and crew, and always fly off of grass. I chose the Aeronca heel brakes as I wanted to keep the original rudder bar instead of pedals, and have a stone simple system on minimal weight and complexity.
Talking about CG, I ran across this sketch that I used in class. Russ mentioned something about CG geometry calculations so I thought that I would post this. I have no idea what it means but I thought that I would offer it in the face of all that propellor techinal stuff. Interesting topic! Switches Image Unavailable, Please Login
Russ, what will the markings look like on you Camel? I have been asked to do some artwork on the Sopwith Camel and need some authentic WW1 markings Switches
Mine will be a 208 Sqn. plane in 1918, serial D1845, plane "C". Top surfaces PC-10, bottom surfaces linen, wooden surfaces a dark cherry and metal left natural aluminum. Similar to Robert Taylor's "baloon buster" (see attach)ed ;Here also are two Microsoft Paint sketchs over the framework and a similar Camel using the color chips. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Russ- I probably have at least a couple hundred images of Camels (WW-I) from multiple sources. I can send you a DVD with them, if you like. Most came from Colin Owers, who likes to share images. I have 5-10K WW-I aircraft images, many originals, never bothered to count. Bob can vouch for the fact I have over 100 images on the Albatros C.XII, way more esoteric than the Camel. Taz Terry Phillips
Yep, Taz. That Albatross book is one of the nicest I have ever seen. Exquisite drawings, great photos, and a mountain of information.
Russ- Got it. My DVDs and mailers are on the way. As soon as they arrive, will zap one out to you. Taz Terry Phillips
Thanks, Taz. On the bad news side, I re-did the wt & balance spreadsheet and this time came up with 28% MAC with me in it, min fuel. And this is with a lot of best guessing, so as originally predicted, the wt and balance will be close. On the blind hope method, the original had much heavier fuel behind the however lighter pilot. We'll find out pretty soon.
In my humble knowledge of such things, the 28% CG shouldn't be too bad if the CG range is 25-30% 0f the MAC. I don't know how tolerant the RAF 16 airfoil is but I would bet that 28% is okay. Just a Scientific Wild Assed Guess.
Thanks Bob abd Taz I spent some time last night studying up on some very basic aerodynamic stability concepts such as neutral point, pos and neg stability, static margin and so on. A big lesson for mw was that when you look at the original Sopwith design and WW1 flight reports, you can see that it was designed with some inherent instability (low stability) to make it a good fighter. I am understanding the original design more, and certainly see how it was no Pup. A basic instability makes a better fighting plane with the characteristics of wanting to change direction more easily. It's clear how this was designed into the Camel from the original dimensions and weight placement. Robert at Airdrome has done a really great job from the beginning of weight management on this plane, and we'll see what the final weights and balances are with my geriatric non-ww1 frame . I know he shoots for 18 - 28% MAC, and I've seen some folks quote 28 - 33% MAC in my reading. It would be interesting to se an original Camel wt and balance with all that fuel back there - it must have had a cg at > 30% MAC. Actually, learning about all of this has made this little project even more fun, and I do enjoy everyone's experience and input!
I was thinking about the same thing since my stability is questionable some times. I can turn on a dime too but sometimes I end up in a spin but I don't lose sight of the dime. Back to serious. I WAS thinking about the successful fighters that were " on the verge " of losing it most of the time to enhance their agility. Kind of like the Giant Slalom skiers, always near the edge of disaster. The little Russian " Mosca" is one example. Mass is short coupled and the airplane is quick in flight but a twitchy little assassin at low speed. One can see this in the Camel and the Siemans-Schukert D-V. On the other end of the stick all you have to do is to look at the B-17 and it says stability. It certainly is a perfect bombing platform when it's in the grove.
