WWI Replica Safety

joepilot · 26 March 2009, 03:24 PM

Gents,

Outstanding forum - good, bad, and the ugly. I appreciate the vast opinions and the videos to remind me that to be human is to err.

I am currently building a Fokker Dr.1 with Ron Sands plans and the builder's forum is outstanding to say the least, especially for this novice builder. I have to laugh and cry at the same time with the quote of a famous Chinese curse:

"May you live in exciting times" - or something like that.

This is an outstanding forum for questions on flying the WWI birds. I am quite interested in the thrust-to-weight ratio discussions of the radials out there. I am considering the Continental 670 or the Russian M-14. So any information or advice (I know that will be difficult for this group to give advice, but hey its a risk I am willing to put out there

!!!) will be greatly appreciated.

Additionally, I am quite interested in the stall and engine out characteristics for the Triplane. Something other than: "Less than you want" would be helpful!!!

Thank you GWFM guys for the advice on the larger ailerons (I'll touch base with you in the future) and the bungee cords in the landing gear. Can't wait for another long Toronto layover - say hi to Edward for me.

As the creator of the Cockpit Resource Management (CRM) 6-hour course and related material for a large flight school, I can say that statistically 70 to 80% of all aviation accidents are caused by human error - distraction, rush-to-comply, and Situational Awareness lead the pack. In reading this thread, I was impressed with "paying attention" to what we are doing and never let your guard down. I needed to read that - thank you.

I leave you with a famous quote from a great American Philosopher - Dirty Harry:

"A man's got to know his limitation" - 1975

Outstanding Thread - keep the cards and letters coming,

C'ya
Joepilot
check 6

Butch · 26 March 2009, 04:45 PM

Joe,
When I flew the Swanson built SPAD 7 up to NY (thanks to Baldeagle) I was comforted by it's lack of glide ability. Power off was like a 30 degree low drag bomb pass. Oh sorry, you're an Eagle geek. To rephrase, I always felt that any par four fairway was adequate space due to the steep glide angle. More comfortable with that analogy? The lack of power off performance can be an asset; I always knew where my options were and they were more numerous than in my Skybolt. You can shoehorn the WW1 types into small places. That said, I chose my ground track carefully, no extended flight over non-hospitable terrain.
Thanks for the call and the thought today,
Pete

Joe Perkel · 26 March 2009, 05:56 PM

Quote:

Originally Posted by joepilot

Outstanding Thread - keep the cards and letters coming,

C'ya
Joepilot
check 6

Welcome to the thread Joe,

The thread has surprised me in it's relevance to the subject at hand, and in the valuable participation and professionalism displayed by the membership. The recent discussions regarding tail wheels, and ground tracking of these replicas is a fine example of this.

It's also been a reminder to us all to be very wary of complacency with regard to basic airman-ship, and decision making processes.

I'm very pleased to see how it has progressed, and hope all have found it equally productive.

j ferguson · 26 March 2009, 06:45 PM

Quote:

Originally Posted by RFC Pilot

Not sure if someone mentioned this already (too many pages to look through), but that is actually something we do at the Museum when we redo the bungies. We rock it by the wings a few times, to settle them, then check a couple of things.

1) Are the cords laying right.

2) Are the wings level.

3) Is the gear on each side compressed the same with it is sitting on the ground.

and

4) by pushing down on the wing tip, does the suspension give the same amount one each side.

It could be that the article Jeff was recommending is the same one that's in posts 16,17, & 18 right here in Von Writter's Thread about his 90% DVII. The story is written by Corky Meyer and has a short section on removing the squirrels by tightening the bungees and how they determined whether they were tight enough during WW1

joepilot · 27 March 2009, 04:37 AM

Thank you for allowing me to join the discussions. I read earlier about the Continental W670 developing 525 lbs torque at T/O RPM. Questions:

1. What size prop would you swing with this engine?

2. M-14D - tough to find info on it. Lots of M-14P. Any idea where to find info?

3. What is the torque at T/O RPM for the M-14D?

4. GWFM guys - what engine do you have on your Tripes? What kind of torque do you get? And how much do your Tripes weigh? Of course I know these are very personal questions, especially on the first date!!!

Pete, good words. And yes I know the difference between slicks and high-drags. One looks good in a suit and the other in a dress

Any information about radial engines, prop size, rpm, torque, etc. is greatly appreciated from anyone flying round motors. I have no experience with a round motor so whatever you got I'm a listening!

C'ya
Joepilot
√6

Flysafe · 27 March 2009, 05:12 AM

Joepilot, the GWFM operates a variety of powerplants on the aircraft. On the triplanes we have one with a 165 HP warner and one with a 230 HP Jacobs. We operate two versions of the W670, aircraft and tank engine on an N28 (aircraft) and a 1 1/2 Strutter (tank). We also have a M14 for the Camel, but I am not sure which specific variant it is.

In my opinion the 165 HP Warner is a little low on HP/Torque. The Jacobs is excellent, other than it's "shaky Jake" vibrations and the joys of the wobble pump for start.

The W670 is a great engine there are some issues with setting up the tank engine, and if you go that route we can guide you along so you learn from our experience. We have no experience with the M14, but there is a Culp Special on the field with one and the discussions I ahve had with the owner are that it is a great engine.

The big issue with radials is parts; making sure you can get them and you have a reasonable number of spares on hand. Areas where we have experienced a need for attention are; mags, carbs, starters and wiring. Quite often you get an engine with low hours but lots of years on it and many of these components have not been replaced. Access to mags, carbs and starters is a challenge and if you need new ignition wires it can be quite an exercise to replace them. I would personally invest in having the aforementioned parts overhauled or replaced if there is any doubt as to their vintage or condition.

We find the key to operating radials is treating them properly. Always pull the prop thorugh before start. Proper warm up before takeoff. Gradual power changes and cruise power that is high enough to keep operating temps reasonable, but not to high. Power on descents to prevent shock cooling and make sure you follow the manufacturers shutdown RPM values to clear oil from the engine.

As to a W670 or an M14, personal choice. One thing to consider is the M14 is a slightly smaller diameter than the W670.

With respect to stalls and engine out on the triplane, they are both relatively benign if you respect them. The DRI has a big fat airfoil thhat has excellent low speed characteristics with good aileron response even at low speed. I have evaluated the stall using normal test practices, level flight, speed reduction of 1 kt/sec power on and power off or on as required. Lots of warning before the stall with buffeting. The stall will occur in the 38-42 knot range, however, the exact value will be very aircraft specific and dependent on your pitot-static setup. The stall is a straight forward moderate drop of the nose, with no noticeable tendency to roll off, except if you do power on stalls. Recovery uses the normal technique and the altitude loss can be minimal, but the overall sink rate can be high.

Engine out glide ratio is very poor. The aircraft has lots of wing area, but no aspect ratio and lots of drag. It is conservatively 1:1. The airplane can land and stop in a short distance so field choices can offer a lot of options, but you need to make sure you can get there. To put it in perspective at our home field the circuit is 800 ft AGL. With no wind if I fly a tight circuit and go abeam the threshold and pull the throttle to idle I will just safely make the active runway with a continous 180 degree turn.

The DRI is a fun aircraft to fly. Good stall characterisitics and if you respect its poor glide ratio, limited aileron authority in a crosswind and poor ground visibility you will have lots of fun and safe flying.

Joe Perkel · 27 March 2009, 11:49 AM

With regard to radial engines, I am still in conflict (bewildered) with myself. The problem is this conflict between the original numbers, and modern availabilty,..nothing new here. Still, here is the response I received last year in an inquiry to a major overhaul shop here in the U.S. regarding the needs of the Sopwith Baby.

Quote:

Dear Joe,
I appreciate you contacting us as a possible source for an engine for your project. Unfortunately, there are not many reliable antique engine options in the horsepower range that you will be needing. The Warners, Kinners, Leblonds, and so forth are not only early technology and not overly reliable, the parts situation has gotten to the place that the engines are very difficult to support. If I were looking for an engine for an experimental project in your weight and horsepower range I would explore the Rotec R2800 or R3600 engines. They are new technology, parts are plentiful, and the only disadvantage that I know of is that the factory is in Australia. They have a great website with plenty of information. Good luck!

Talk about the "State of Confusion",... no wonder eh? This makes the R3600 attractive although it falls short in torque, but makes up for it a bit in weight.

I have since come to the conclusion that the R3600 is absolutely perfect for an authentic Pup replica, the numbers are really good. It would also be equally effective with my plane on wheels only. The floats however, will cut wheeled climb performance by approximately half. Still, there are a number of C-172's on floats flying around out there with 150 hp, (albeit effectively a two place machine).

Look at the weights and specs for the 172 on floats.

Horsepower: 150 Gross Weight: 2220 lbs
Top Speed: 94 kts Empty Weight: 1450 lbs
Cruise Speed: 92 kts Fuel Capacity: 42.00 gal
Stall Speed (dirty): 45 kts Range: 435 nm

Takeoff
Ground Roll: 1620 ft
Over 50 ft obstacle: 2390 ft

Rate Of Climb: 580 fpm
Ceiling: 12000 ft

Flysafe, do you see where I am going here with this thought process?
Is this an apples and oranges comparison?

I am concerned about the overall age, parts scenario, and weight of a W670 on this original airframe. M14 is too much, I cant seem to find the smaller version RobW had mentioned previously.

RobW · 28 March 2009, 07:15 AM

Quote:

Originally Posted by Joe Perkel

I am concerned about the overall age, parts scenario, and weight of a W670 on this original airframe. M14 is too much, I cant seem to find the smaller version RobW had mentioned previously.

Joe,
Take a look at this page: Steen Aero Lab - Aircraft Products - Vendenyev M14P / M14PF Radial Engine Information

These folks concentrate on the higher HP versions of the M-14, but they can probably talk the M-14D. The difference between the Higher HP versions and the D version is that they remove the gear reduction and de-rate the engine to 220 HP. They describe it as a replacement for the W670.

Rob

Machinbird · 28 March 2009, 03:14 PM

In this post, Flysafe made two key observations relevant to replica safety.

Quote:

Originally Posted by Flysafe

..............................
There are some ways to make this better on the DRI; use the larger more effective ailerons and make sure that when you are sitting in the cockpit that full aileron movement is achived before the stick hits your inner thigh. It is common to see full stick movement be impeded by pilot appendages. .................................................. ...................

I have flown all kinds of taildraggers for over 30 years. everything from Cubs to DC-3's and WWI replicas are the most challenging aircraft I have flown in crosswinds. As I was told years ago, you don't stop flying them until they are tied down.

The first observation is something we as builders can influence significantly by minor alterations to the plans. Just like runway behind you and sky above you, control throw that you cannot use does you no good.
One of the first thing a builder does is sit in their newly built fuselage to get an idea of the view. Often a broomstick is used to simulate the stick. Well, that is the time to determine whether you will have control throw problems. The sooner you detect the potential for a control throw problem, the less investment you have in time and money in what is potentially a serious liability. After all if you are flying an aircraft that has restricted controls, you are being a "test pilot" and you might discover something you don't want to find. Small alterations in the stick hinge point heights and control arm distances can give you back the aileron (or pitch) deflection you need. But don't forget to look at the effect on control forces of your adjustments. It is no fun flying a plane where the stick feels like it is buried in sand.

The observation about flying the plane all the way until tied down is extremely valid, particularly with tail draggers. I have a story on this subject I can relate later if no one comes up with a better one.

Sid

Joe Perkel · 28 March 2009, 03:57 PM

Quote:

Originally Posted by RobW

Joe,
Take a look at this page: Steen Aero Lab - Aircraft Products - Vendenyev M14P / M14PF Radial Engine Information

These folks concentrate on the higher HP versions of the M-14, but they can probably talk the M-14D. The difference between the Higher HP versions and the D version is that they remove the gear reduction and de-rate the engine to 220 HP. They describe it as a replacement for the W670.

Rob

Rob,

Thanks for the info, now I understand why I had trouble finding it.

I had seen the Steen site, and even the manufacturers site, with no mention of the de-rated version (perhaps I missed it). Several other models are in the pipeline though, mostly for aerobatic craft.

I am hesitant to exceed the original Clerget weight of 381 lbs, or torque output of 546 ft pounds. The image above, is an unsettling reminder of what can happen when the limits of the longerons are exceeded. However, this incident is apparently attributable to wood rot in the humid environment of Mediterranean operations. The engine fell through forward upon landing after a mission. Even so, this image has haunted me a bit since I discovered it.

Still, I am conflicted here. There is an upper limit to what can be mounted on these longerons before it's time to abandon authenticity in favor of a steel airframe. My "gut" says, that the Clerget, was pretty much there. Bottom line is that I'm still very unsure about how to proceed, so still evaluating this. This is why the recent interest in a land-plane configuration just in case.

Thanks Rob!