diff --git a/doc/hamproptbl.m b/doc/hamproptbl.m
index 9b5c6c0..e8992e5 100644
--- a/doc/hamproptbl.m
+++ b/doc/hamproptbl.m
@@ -1,5 +1,7 @@
 #!/usr/bin/octave
 
+graphics_toolkit ("gnuplot");
+
 aftbln = 5;
 
 afval = [80 100 125 150 175 200];
@@ -45,7 +47,7 @@ for t=1:2;
 endfor;
 printf("\n};\n");
 
-clf;
+f=figure("visible","off");
 plot(afval,afcpc(1,:),"1+;CP 1;",...
      afval,afcpc(2,:),"2+;CP 2;",...
      afval,afctc(1,:),"3+;CT 1;",...
@@ -58,9 +60,9 @@ grid on;
 xlabel("AF -- Activity Factor");
 ylabel("CP/CT Factor");
 title("CP/CT versus AF");
-print("propafcpct.eps","-depsc2","-portrait","-color");
+print(f, "propafcpct.eps","-depsc2","-portrait","-color");
 
-clf;
+f=figure("visible","off");
 plot(afval,afcpc(1,:)-polyval(afcpp(1,:),afval),"1+-;CP J=0 error;",...
      afval,afcpc(2,:)-polyval(afcpp(2,:),afval),"2+-;CP J>=0.5 error;",...
      afval,afctc(1,:)-polyval(afctp(1,:),afval),"3+-;CT J=0 error;",...
@@ -69,7 +71,7 @@ grid on;
 xlabel("AF -- Activity Factor");
 ylabel("CP/CT Factor Approximation Error");
 title("CP/CT versus AF Approximation Error");
-print("propafcpcterr.eps","-depsc2","-portrait","-color");
+print(f, "propafcpcterr.eps","-depsc2","-portrait","-color");
 
 zjstal = 0:0.4:3.2;
 cpstal = [ .05 .12 .22 .35 .49 .65 .82 1.01 1.19 ;
@@ -146,6 +148,7 @@ for t=1:4;
 endfor;
 printf("\n};\n\n");
 
+f=figure("visible","off");
 plot(zjstal,cpstal(1,:),"1+;CPstall 2 Blade;",...
      zjstal,cpstal(2,:),"2+;CPstall 4 Blade;",...
      zjstal,cpstal(3,:),"3+;CPstall 6 Blade;",...
@@ -158,8 +161,9 @@ grid on;
 xlabel("ZJ");
 ylabel("CP Stall");
 title("CP Stall versus ZJ");
-print("propcpstal.eps","-depsc2","-portrait","-color");
+print(f,"propcpstal.eps","-depsc2","-portrait","-color");
 
+f=figure("visible","off");
 plot(zjstal,cpstal(1,:)-polyval(cpstalp(1,:),zjstal),"1+-;CPstall 2 Blade error;",...
      zjstal,cpstal(2,:)-polyval(cpstalp(2,:),zjstal),"2+-;CPstall 4 Blade error;",...
      zjstal,cpstal(3,:)-polyval(cpstalp(3,:),zjstal),"3+-;CPstall 6 Blade error;",...
@@ -168,8 +172,9 @@ grid on;
 xlabel("ZJ");
 ylabel("CP Stall Approximation Error");
 title("CP Stall versus ZJ Approximation Error");
-print("propcpstalerr.eps","-depsc2","-portrait","-color");
+print(f,"propcpstalerr.eps","-depsc2","-portrait","-color");
 
+f=figure("visible","off");
 plot(zjstal,ctstal(1,:),"1+;CTstall 2 Blade;",...
      zjstal,ctstal(2,:),"2+;CTstall 4 Blade;",...
      zjstal,ctstal(3,:),"3+;CTstall 6 Blade;",...
@@ -182,8 +187,9 @@ grid on;
 xlabel("ZJ");
 ylabel("CT Stall");
 title("CT Stall versus ZJ");
-print("propctstal.eps","-depsc2","-portrait","-color");
+print(f,"propctstal.eps","-depsc2","-portrait","-color");
 
+f=figure("visible","off");
 plot(zjstal,ctstal(1,:)-polyval(ctstalp(1,:),zjstal),"1+-;CTstall 2 Blade error;",...
      zjstal,ctstal(2,:)-polyval(ctstalp(2,:),zjstal),"2+-;CTstall 4 Blade error;",...
      zjstal,ctstal(3,:)-polyval(ctstalp(3,:),zjstal),"3+-;CTstall 6 Blade error;",...
@@ -192,7 +198,7 @@ grid on;
 xlabel("ZJ");
 ylabel("CT Stall Approximation Error");
 title("CT Stall versus ZJ Approximation Error");
-print("propctstalerr.eps","-depsc2","-portrait","-color");
+print(f,"propctstalerr.eps","-depsc2","-portrait","-color");
 
 inn = [ 10 6 8 8 7 10 6 ];
 
@@ -367,7 +373,7 @@ endfor;
 printf("\n};\n");
 
 for bldidx=1:4;
-  clf;
+  f=figure("visible","off");
   col=jet(7);
   for t=7:-1:1;
     plot(cpang(t+(bldidx-1)*7,1:inn(t)),bldang(t,1:inn(t)),sprintf("+;J=%3.1f;",zjj(t)),"color",col(t,:));
@@ -387,11 +393,11 @@ for bldidx=1:4;
   ylabel("Blade Angle");
   title(sprintf("%u Blade Propeller",bldidx*2));
   axis([-0.5 1.5 0 70]);
-  print(sprintf("propbldangcp%u.eps",bldidx),"-depsc2","-portrait","-color");
+  print(f,sprintf("propbldangcp%u.eps",bldidx),"-depsc2","-portrait","-color");
   axis([0.0 0.4 0 40]);
-  print(sprintf("propbldangcp%ud.eps",bldidx),"-depsc2","-portrait","-color");
+  print(f,sprintf("propbldangcp%ud.eps",bldidx),"-depsc2","-portrait","-color");
 
-  clf;
+  f=figure("visible","off");
   col=jet(7);
   for t=1:7;
     plot(ctang(t+(bldidx-1)*7,1:inn(t)),bldang(t,1:inn(t)),sprintf("+;J=%3.1f;",zjj(t)),"color",col(t,:));
@@ -411,9 +417,9 @@ for bldidx=1:4;
   ylabel("Blade Angle");
   title(sprintf("%u Blade Propeller",bldidx*2));
   axis([-0.2 0.6 0 70]);
-  print(sprintf("propbldangct%u.eps",bldidx),"-depsc2","-portrait","-color");
+  print(f,sprintf("propbldangct%u.eps",bldidx),"-depsc2","-portrait","-color");
   axis([0.0 0.2 0 40]);
-  print(sprintf("propbldangct%ud.eps",bldidx),"-depsc2","-portrait","-color");
+  print(f,sprintf("propbldangct%ud.eps",bldidx),"-depsc2","-portrait","-color");
 endfor;
 
 # Figure 1 from 1971 Report
@@ -450,7 +456,7 @@ for t=1:7;
 endfor;
 printf("\n};\n");
 
-clf;
+f=figure("visible","off");
 col=jet(7);
 for t=1:4;
   plot(cpec,btdcr(t,:),sprintf("+;%u Blades;",t*2),"color",col(2*t-1,:));
@@ -463,4 +469,4 @@ hold off;
 xlabel("Effective Power Coefficient CPE1");
 ylabel("PBL");
 grid on;
-print("proppbl.eps","-depsc2","-portrait","-color");
+print(f,"proppbl.eps","-depsc2","-portrait","-color");
diff --git a/doc/hartzellf7666a2af.m b/doc/hartzellf7666a2af.m
index f39ccf4..dfc0fee 100644
--- a/doc/hartzellf7666a2af.m
+++ b/doc/hartzellf7666a2af.m
@@ -1,5 +1,7 @@
 #!/usr/bin/octave
 
+graphics_toolkit ("gnuplot");
+
 # diam 192
 
 t = [ 0 5.5 ;
@@ -93,6 +95,7 @@ P = polyfit(74/2-t(:,1)/2.54,t(:,2)/2.54,polyorder);
 
 r=((round(rmin*1e2)*1e-2):1e-2:rmax);
 w=polyval(P,r);
+figure("visible","off");
 plot(r,w,";Approximation;",...
      74/2-t(:,1)/2.54,t(:,2)/2.54,"+;Measurements;");
 line([rcowling rcowling],[0 10],"displayname","Cowling","color","cyan");
diff --git a/doc/p28rperf.m b/doc/p28rperf.m
index 0bff680..f69bf35 100644
--- a/doc/p28rperf.m
+++ b/doc/p28rperf.m
@@ -1,5 +1,7 @@
 #!/usr/bin/octave
 
+graphics_toolkit ("gnuplot");
+
 global const_g   = 9.80665;                     % gravity const.
 global const_m   = 28.9644;                     % Molecular Weight of air
 global const_r   = 8.31432;                     % gas const. for air
@@ -75,6 +77,7 @@ CD0geardownflaps40=CD0geardown+0.06;
 
 alt=0:100:15000;
 [p t rho]=icaoatmo(alt);
+figure("visible","off");
 clf;
 ax=plotyy(alt,p,alt,rho,@plot,@plot);
 title("ICAO Standard Atmosphere");
@@ -188,7 +191,7 @@ set(ax(2),"ylim",[0 1200]);
 set(ax(1),"ycolor",[0 0 0]);
 set(ax(2),"ycolor",[0 0 0]);
 legend(ax, "location","northwest");
-legend(ax, "show");
+#legend(ax, "show");
 print("p28rslgndrun.eps","-depsc2","-portrait","-color");
 
 clf;
@@ -207,7 +210,7 @@ set(ax(2),"ylim",[0 80]);
 set(ax(1),"ycolor",[0 0 0]);
 set(ax(2),"ycolor",[0 0 0]);
 legend(ax, "location","northwest");
-legend(ax, "show");
+#legend(ax, "show");
 print("p28rslgndrunprop.eps","-depsc2","-portrait","-color");
 
 CD0s=[CD0 CD0geardown];