DR-1 (Sands): Builders Group

[vongrube]

Greatwarpilot,
Yes, I agree with you on the varied pilot reports concerning the Dr1. And yes, I suspect it has something to do with the experience of the pilot in question.
I have read from some reports that said the Dr1 was totally unstable and almost impossible to control. I find statements like that highly suspect. I can't imagine anything for "impossible" to control than a helicopter..and I have mastered those. So I generally discount those types of statements as coming from some of the more inexperienced pilots out there.
Statements such as "unstable" are so relative. I guess if you are used to flying "hands-off" in Cessnas and Pipers then I suppose the Dr1 qualifies. .Try doing that with a helicopter and the'll be notifying your next of kin!.
Also...I went with the Sands modification on the rudder, a .049 thick kingpost, AND a .035 tubing insert that spans the distance of both hinges and then some.
Don't want that sucker departing the airframe!

[vongrube]

Jim,
I feel that there could be several alternate designs for the internal structure of the subwing. By the time you build the steel shock boxes, tie them together with a rigid aluminum axel box, then add ribs,and stringers...THEN cover everything with plywood....well....that thing ain't going anywhere!
Personally..after building my subwing..I think its waaaaaay overbuilt!
To answer your question..yes. I feel you could probably get away with another way to spread the shockboxes AND mount the ribs. That ply is gonna cover and tie it all together anyway.

[van der Laan]

On quality of ride issues:

Don't forget that most of the DR1 horror stories are most probably attributed to horribly built airplanes rather than bad pilots and or designs. Sure, the odd novice gets in and scares himself to death on occasion, but most to the folks flying them, even for a short time are high time pilots. From what I've seen, most of the reproductions if they were RANS or WAG Aero Cubs would be considered ‘no pass’ Junkers!

There is no accounting for poorly rigged and built aircraft, no amount of pilot can make it fly right!

[vongrube]

Van Der Laan,
I disagree with you on your comments. I have seen quite a number of replica triplanes over the years. I have yet to see a Dr1 that was horribly built. While I have seen some with slight modifications that I personally didn't agree with, I wouldn't have considered any of them "junkers".
One particular triplane I saw had a reputation for having very stiff ailerons. When I investigated as to why this might be the case, I found that the aileron cable routing was non-standard for the aircraft. But it was still acceptable, and airworthy.
I still stand by my conviction that most fixed-wing pilots have little to no experience with unstable, and twitchy aircraft. They then climb into the triplane and experience quite a shock, especially if they are a low-time pilot, or have limited tail-wheel experience.

[vongrube]

Van Der Laan,
However...if you were refering to the construction practices of the Fokker factory in 1917, then I totally agree with you. Simply atrocious!
In modern replicas though, rigging does have a lot to do with whether an aircraft flies well, or traverses the sky like a sidling land crab!
Even problems like adverse yaw in the triplane can be taken out, or greatly reduced with proper rigging and slight internal modifications to the control systems,
If one were so inclined.

[Dogtail2]

Originally Posted by Fritz Kempf

Pete
The bending was ok once we understood that we needed to increase the radius of the bending die with another piece of bent metal to keep it from cracking.
The rivets were the worst, not having ever done this before and not having the tools was a .........etc

Ed,

Excellent post! Thanks for sharing this with us. I too recently found out what a Cleco is

Franzkait, instead of just showing us a pretty picture, how about telling us how it was done?

[franzkait]

Dogtail,I am looking for a foto how it is made, give me 1 day

[van der Laan]

Originally Posted by vongrube

Van Der Laan,
I disagree with you on your comments. I have seen quite a number of replica triplanes over the years. I have yet to see a Dr1 that was horribly built. While I have seen some with slight modifications that I personally didn't agree with, I wouldn't have considered any of them "junkers".
One particular triplane I saw had a reputation for having very stiff ailerons. When I investigated as to why this might be the case, I found that the aileron cable routing was non-standard for the aircraft. But it was still acceptable, and airworthy.
I still stand by my conviction that most fixed-wing pilots have little to no experience with unstable, and twitchy aircraft. They then climb into the triplane and experience quite a shock, especially if they are a low-time pilot, or have limited tail-wheel experience.

Well, there is no accounting for taste I guess (or notions of “fine” vs. “rough” examples). I’ll bet I’ve seen more DR1 examples than you can find out there in California and from my close-up survey of ships from Texas, the South East, the North East and the Mid West you generally find them built by folks that have never built anything before. As such, their notions of engine mounting, balance, rigging , mixture of rigging, tension of rigging, welding for aircraft, acceptable wood working and design change limitation are exercised without having ever done it before (no previous aircraft) and because of the rarity of the DR1 they do not have any other aircraft to either look at as an example or fly to determine something is wrong with theirs.

If you are building a FALCO, a RANS, a PITTS, a SKYBOLT even an exotic composite, there are tons of web sites that show the trial and tribulation of the process, but if it’s a DR1, you are on your own for the most part. This results in a first time builder ending up with a machine for which there is no “baseline”: smart people understand that’s the problem.

If you take an experienced builder and put him on the DR1 you get a great “baseline” machine, if you put a first time builder on it, more often than not you get bad welding, bizarre design changes, twisted spars and a airplane the builder takes up one time and then writes an article about, claiming IT’S THE MOST DANGEROUS MACHINE EVER DESIGNED, when in reality its just a really poorly built aircraft and the fact that it’s a taildragger and a ww1 design is just piling on to the problem list.



MT 2 CENTS

[vongrube]

Van Der Laan,
Well...if you HAVE seen quite a number of triplanes, and they are really as bad as you say..then thats pretty scary.
I would then have to agree with you on your point. A badly constructed airplane would indeed complicate the experience. When combined with an inexperienced pilot.....well, thats a combination for disaster.
I would LIKE to think that the aircraft I have had the opportunity to examine were indicitive of the lot. But..maybe thats not the case. That would surely be a shame then.
I do like your point on first time builders. I would even go so far as to NOT recommend this kind of aircraft for those types of builders. There is simply not enough guidence and direction given with just a set of blue prints here.
Although there are some very talented people out there, this project is so much more complicated than building some chopper, or hot rod.
I feel that forums like this do a wonderful service to those who are gutsy enough to attempt this. Be safe!

[AchimEngels]

Hi,

regarding those loops.

Just take a rod, drill a hole into it to match the diameter of the tube you want to bend, fix the rod in the lathe, put the tube in the drilled hole and start wrapping it around the rod like a spring. You can then cut the wrapped "spring to half rings and quarter rings. No heat neccessary. At least this works perfectly with 8mm diameter tubings of 2mm wall thickness with a strenght of 52kg/ sq.mm. This is what I use and a bit stronger than what is specified in the Fokker factory drawing for the E.V.

Hope this helps.

Cheers!
Achim