gofastclint Posted March 5, 2009 Share Posted March 5, 2009 There is a chap in South Australia who is building an all metal fuselarge Sonerai with a Jabiru 3300 engine. Looks briliant only half finished. this particular aircraft has a VNE of 173 knots, I have heard of these Aircraft cruising just under VNE with a Jab 2200, so with this engine it will be well over VNE, what strengthening modifications would be need to alow the aircraft to safely atain a VNE of 250knots? Link to comment Share on other sites More sharing options...
Guest brentc Posted March 5, 2009 Share Posted March 5, 2009 I think you'll find that the Sonerai won't come close to 173 or even 150, you may be the victim of some poetic licence by the person that told you that as they say! That being said, a larger engine doesn't always mean that it will go that much faster. A Cirrus SR22 for example at the top end gets an extra 10-15 knots from the turbo charged variant which is 50 hp more. There is a famous Sonerai around that has oxygen and a 912S that cruises up over 20,000 ft with a very high TAS, but from memory it's still not up near 173. All that aside, you would need some massive structural modifications to bring a VNE from 173 to 250 and realistically depending on the design of the aircraft simply may not be possible. As for metal being stronger or better than fabric such as the original Sonerai, don't be confused by that, remember that even a Mustang has fabric tailfeathers! Link to comment Share on other sites More sharing options...
gofastclint Posted March 5, 2009 Author Share Posted March 5, 2009 If I fly at 130 knots with 65hp, what speed at best guess would I travel at with 120hp? Link to comment Share on other sites More sharing options...
Ultralights Posted March 5, 2009 Share Posted March 5, 2009 If I fly at 130 knots with 65hp, what speed at best guess would I travel at with 120hp? you might get 140. or 150, if your lucky. dont forget, drag forces are exponential, doubling the speed, quadruples the drag. and hence the power required is 4 times as well. Link to comment Share on other sites More sharing options...
djpacro Posted March 5, 2009 Share Posted March 5, 2009 If I fly at 130 knots with 65hp, what speed at best guess would I travel at with 120hp? assuming constant speed props, nearly 160 kts, but will it really do 130 kts with 65 hp. Doing the sums with fixed pitch props is a bit more involved and the speed increase probably won't be as high as for a constant speed prop. you might get 140. or 150, if your lucky. dont forget, drag forces are exponential, doubling the speed, quadruples the drag. and hence the power required is 4 times as well. Nope.And don't forget the flutter clearance for a higher VNE. Link to comment Share on other sites More sharing options...
Guest brentc Posted March 5, 2009 Share Posted March 5, 2009 What are you flying at 130 knots with 65 hp? Link to comment Share on other sites More sharing options...
gofastclint Posted March 5, 2009 Author Share Posted March 5, 2009 What are you flying at 130 knots with 65 hp? Hey Brent, sorry, my bad. That was more of an if than for real. The figures I stated were an average from a few formula Vee sites. They claim with single seat Sonerai and race levels of fuel a 65-70hp vw engine. 130knots can be reached. Is that a bit optimistic? Link to comment Share on other sites More sharing options...
Guest brentc Posted March 5, 2009 Share Posted March 5, 2009 Maybe as a top speed but probably not in the cruise at cruise power. I'm not familiar with the single seat Sonerai however if it's smaller than the 2 seater then I guess that's possible. Link to comment Share on other sites More sharing options...
djpacro Posted March 5, 2009 Share Posted March 5, 2009 Racers run their engines way above redline rpm so they're getting way above the rated power of the engines. I'll believe the 130 kts but not the 65 hp. So, as for how fast with the Jab 2000 will depend on how hard you want to work the engine. Link to comment Share on other sites More sharing options...
gofastclint Posted March 5, 2009 Author Share Posted March 5, 2009 130 kts but not the 65 hp[/url]. So, as for how fast with the Jab 2000 will depend on how hard you want to work the engine. I though the formula vee engines were unmodified. Or is that only a capacity restriction? Link to comment Share on other sites More sharing options...
gofastclint Posted March 5, 2009 Author Share Posted March 5, 2009 Its amazing to think that nemesis 1 gets 273 knots on the straight and level on 100hp. Race pace is lower. Link to comment Share on other sites More sharing options...
djpacro Posted March 5, 2009 Share Posted March 5, 2009 The rules are here, hhhmm it says 65 hp at 4000 rpm. Link to comment Share on other sites More sharing options...
gofastclint Posted March 5, 2009 Author Share Posted March 5, 2009 There is a big difference between a VW beetle and a formula vee open wheeler. Yet they both share the same engine. Link to comment Share on other sites More sharing options...
Guest JONC Posted March 5, 2009 Share Posted March 5, 2009 There is a big difference between a VW beetle and a formula vee open wheeler. Yet they both share the same engine. I have a 100 hours in a sonerai with a 914 in it. It does'nt go much faster than the others. Brian Turner in qld has a rotax 912s in it and has built it purely for speed. It only does 140 knots. The aircraft is designed for manouverability over speed which makes it great fun to fly Link to comment Share on other sites More sharing options...
Guest brentc Posted March 5, 2009 Share Posted March 5, 2009 I know of a Sonerai in Vic that had a small overspeed incident where there was some confusion over who was flying. It went over VNE and a fabric panel tore off the side! Link to comment Share on other sites More sharing options...
Guest JONC Posted March 6, 2009 Share Posted March 6, 2009 I am familiar with that incident, seeing that I fly that aircraft. In fact, it was not dacron on the side as normal, but fibreglass which became unattached. The aircraft was also near VNE Link to comment Share on other sites More sharing options...
gofastclint Posted March 6, 2009 Author Share Posted March 6, 2009 I am familiar with that incident, seeing that I fly that aircraft. In fact, it was not dacron on the side as normal, but fibreglass which became unattached. The aircraft was also near VNE A bloke I know replaced the side fabric with metal and it works a treat, stops the side getting damaged by your hands on the in and out. Link to comment Share on other sites More sharing options...
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