DR-1 (Sands): Builders Group

[mustang]

I have followed the debate on internal corrosion in welded steel tube fuselages with interest. Internal flushing with hot linseed oil was a pretty standard practice in these structures at one time. Any safeguard against out of sight corrosion can only be beneficial.

On the technique of pressure testing the structure for corrosion holes, pin-holes or cracks I encountered an interesting method when converting to a Zlin aerobatic aircraft in Czecho-Slovakia some years ago. This particular aircraft type had a welded steel tube centre section, a highly stressed component of the structure. An always visible in the cockpit pressure guage was tapped into the tubes and the entire structure was pressurised with nitrogen.

Any crack in the structure, either before or during flight was instantly detectable to the pilot by the loss of pressure and the aircraft not flown or promptly landed.

I had not encounted this method before and it appeared to me to be a smart
way of increasing safety by the addition of the weight of one small pressure guage.

regards

Mustang

[hank jarrett]

As far as I know differential pressure was originally patented by either Sikorsky or Boeing Vertol on rotor blades. Each blade was put under slight pressure and there was a gauge in the root of the rotor. Loss of pressure and you didn't fly. Vertol (or Igor) didn't like that there was a patent and put a vacuum on their rotors to get around it. It's been years since I looked at a rotor head but when I was in the Navy it seems all of them had the pressure gauges.

[Tim]

I recall working on an S-55 helicopter that had pressure indicators on each rotor blade at the root of the blade.

In the heavy equipment/diesel engine businesses airfilters are equipped with a simple indicator that I plan to use for my frame. As far as I can see anything over ambient is lots of pressure so I don't figure I have to get crazy with plumbing and fittings.

[Rittersbach]

Greetings Gentlemen,

I have to say that this thread is very interesting. Can anyone tell me what the finished flying weight will be for your Dr.1?

Thanks!

Ritt

[Maxim08]

FYI and keeping with the German theme, Porsche pressure checked the chassis of their 917 race cars which were tubular structures.
Regards,
Maxim08

[Jim Bruton]

Rittersbach,

Hard to say exactly, mostly because of the engine choices. A LeRhone, a modern opposed cylinder Lycoming, a Rotec 150hp and an M-14 or Continental 200hp all weigh different amounts, and the addition of counterbalance weights will give a different end result. Hopefully, no matter the weight, the centers of balance will come to the same place.

[Rittersbach]

Jim,

Thanks for the reply about the weight. The reason I was asking was to give some indication as to the performance for take off and for cruising. I have no idea what HP you guys would be running but I would think that the weight would play a huge role in performance.

Thanks!

ps. Jim, has anyone ever told you that you bear a strong resemblance to Fred Couples.

Ritt

[joepilot]

Tripe Builders et. all,

I began working on the 3/4 inch tubing aft of the cockpit. After much time and frustration, I can say I have almost completed tack welding the entire fuselage. All I lack is the most aft bay cross tube and then welding the longerons together which will eventually hold the rudder. Now it is time for a good cigar and whiskey to enjoy the fruits of my frustrations.

C'ya
joepilot

Beginning the Cross Tubing


Almost Done looking from the engine aft


Almost Done looking forward

[greatwarpilot]

Great work Joepilot. I'm glad to see that you're making such good progress.

If the weather co-operates we should have some pictures of our triplane's first post rebuild flight to share! Should be fun to get our tripes up with yours one of these days.

Cheers

Edward

[Dogtail2]

Great work Joepilot

What frustrations did you experience, for those of us following?

Pete