shallowskiff Posted October 5, 2011 Report Posted October 5, 2011 Can you guys give me an idea of what type of groundspeed to expect at different altitudes? Just an average like what you would use for flight planning. 10-12000 ft 14-16000 ft 18-20000 ft etc. Quote
Parker_Woodruff Posted October 5, 2011 Report Posted October 5, 2011 What groundspeed? Your true airspeed minus whatever headwind you are unfortunate enough to get that day. Quote
shallowskiff Posted October 5, 2011 Author Report Posted October 5, 2011 Quote: Parker_Woodruff What groundspeed? Your true airspeed minus whatever headwind you are unfortunate enough to get that day. Quote
rbridges Posted October 5, 2011 Report Posted October 5, 2011 Quote: shallowskiff True! What are your speeds? Help a man out! Quote
thinwing Posted October 5, 2011 Report Posted October 5, 2011 I have a graph of max. TAS vs altitude worked out by an MSC in colorado that showed realistic speeds for tLS/Bravos...its stops at 217kts @22k...I can dig it out of the a/c later today and post it..kpc Quote
thinwing Posted October 5, 2011 Report Posted October 5, 2011 and from memory about 190kts true @ 13 to 15k,200kts true 15 to 17k,210ts true 17 to 19,215 kts @ 20k or so...kpc Quote
WardHolbrook Posted October 5, 2011 Report Posted October 5, 2011 When it comes to flight planning, why not use a program like Flitesoft or any of the others like it out there? They're not that expensive and are bang on accurate. It's what I use whether I'm flying a piston single or one of the company's Falcon 900s. Once you get it "dialed in" for your airplane and the way you fly it (very easy to do) it's as accurace as the winds aloft forecasts allow it to be - in other words - bang on. In the Falcon, it's normally within a minute or two on the time and within 100 pounds (15 gallons) on a non-stop, coast-to-coast trip. On piston aircraft it's within a gallon or so on just about any given trip. Optimized route and altitude selection are a piece of cake. (The altitude you use really does make a difference and rules of thumb are often wrong.) You can do "what if's" all day long. Additionally, it does a progressive weight and balance calculation so you can safely load right up to the max. Quote
jetdriven Posted October 5, 2011 Report Posted October 5, 2011 Wow, thats amazing. I assume the same NM/gal as a J up there? Hard to believe it is the same wing. Quote: thinwing I have a graph of max. TAS vs altitude worked out by an MSC in colorado that showed realistic speeds for tLS/Bravos...its stops at 217kts @22k...I can dig it out of the a/c later today and post it..kpc Quote
thinwing Posted October 5, 2011 Report Posted October 5, 2011 Bravos love high altitudes,that wing is loafing down low...i wish it had l/d polars like they plot for modern sailplanes...i think Al hit it totally by accident...as far as same nm/gal as a J..forget it...fuel burn is 20gal per hour at that speed ..so a bravo will scoot but at lousy fuel specifics...kpc Quote
thinwing Posted October 5, 2011 Report Posted October 5, 2011 For flight planning,flt. plan.com...is very accurate...Its Tas/fuel burns per alt. are very accurate without me having to input specifics and of course i love recieving clearances texted to my cell phone..kpc Quote
Parker_Woodruff Posted October 5, 2011 Report Posted October 5, 2011 Bravos ain't pretty on the NMPG number, even up high, unfortunately. Quote
jetdriven Posted October 5, 2011 Report Posted October 5, 2011 So which is better, Rocket 305 or a Bravo? Obviously the Bravo is likely newer. Speed? Useful load? etc Quote
KSMooniac Posted October 5, 2011 Report Posted October 5, 2011 A Rocket will likely happily run LOP and blow the Bravo out of the water for efficiency. I don't know enough about either for useful load comparisons... Quote
jetdriven Posted October 5, 2011 Report Posted October 5, 2011 I suppose either will kick the hell out of a B36TC Bonanza speed or fuel wise? Quote
thinwing Posted October 5, 2011 Report Posted October 5, 2011 The Bravo will kick the hell out of 600 hp Baron both speed and fuel wise...kpc Quote
KSMooniac Posted October 5, 2011 Report Posted October 5, 2011 Quote: jetdriven I suppose either will kick the hell out of a B36TC Bonanza speed or fuel wise? Quote
shallowskiff Posted October 6, 2011 Author Report Posted October 6, 2011 Quote: thinwing and from memory about 190kts true @ 13 to 15k,200kts true 15 to 17k,210ts true 17 to 19,215 kts @ 20k or so...kpc Quote
gjkirsch Posted October 7, 2011 Report Posted October 7, 2011 Economy Cruise of 26/2350 leaned to 17 GPH = 175 True at 10K Power Cruise Figure 155 Indicated at 32/2400 peak plus 50 add 3 knots per 1000 feet of altitiude I have TKS so I am slower! Quote
orangemtl Posted October 7, 2011 Report Posted October 7, 2011 I've used Fltplan.com, which automatically enters projected speeds at given altitudes, based upon the model aircraft entered. I've found it to be quite reliable, so long as I'm entering accurate data. It also enters winds aloft by altitude based on either predicted winds (if it's a day or two in the future), or hiistorical figures for a given date. I've no doubt that either IPad-based apps, or a variety of other sites will do much the same. I've found Fltplan.com to be pretty helpful, though. Give it a whirl. Quote
shallowskiff Posted October 7, 2011 Author Report Posted October 7, 2011 fltplan.com tip looks good. Thank you for the tip. Quote
KSMooniac Posted October 7, 2011 Report Posted October 7, 2011 fltplan.com is a real gem! I've been using it for 4.5 years now and found it to be extremely accurate using the stock profile for the M20J. It works from any web browser, and there are mobile app versions as well. One of the best features it has is offering recently planned routes and recently ATC-cleared routes, so if you are in unfamiliar and congested airspace, you can get an idea of what you will actually be cleared for when filing IFR. Quote
shallowskiff Posted October 7, 2011 Author Report Posted October 7, 2011 Quote: KSMooniac so if you are in unfamiliar and congested airspace, you can get an idea of what you will actually be cleared for when filing IFR. Quote
Awful_Charlie Posted October 8, 2011 Report Posted October 8, 2011 I find the figures in the POH near spot on, but normally plan for the 30"/2200 setting Quote
johnggreen Posted October 9, 2011 Report Posted October 9, 2011 Shallowskiff, I have flown my Bravo for almost seven years now. I'm based in MS and my profile is that I rarely fly less than 500 NM each time I crank the engine. My children are all in NC, VA, DC area. One went to Northwestern, so Chicago used to be a regular trip as well. Factor in a couple of business trips to the likes of CO and/or FL each year and well, you know why I have the Bravo. 90% of the time it is my wife and me with weekend bags. With TKS full, we are at gross. Sometimes I have to download a little fuel so I have pretty much perfected the max range speed/range/power combo for my airplane and make a note of almost every flight in my airplane flight log which stays in the airplane. By the way; even with TKS, my Bravo cruises about 4-7 knots over book speeds at gross! Yea, I'm a lucky man. ANYWAY: You asked a legitimate question and I do have the answers to a limit. The limit being is that I do not use high power settings. The TIO-540 AF1B is one of the lower horsepower TIO-540 varients so most of the cruise power settings given by the POH are well above 75%. All those figures are in your Lycoming owners manual and make for very interesting reading. To give you a feeling for power percentages, depending on altiude and temperature, according to the LOM (Lyc owner's manual) 75% can come at as little as 2200 rpm and 30" of manifold pressure. 2400/30" puts out about 220 h.p. wich would be about 80%. These figures will also vary according to whether you use best power (1650) or peak TIT. I use best power 90% of the time. As to where I fly. I try to fly from 13m to 17m. Never higher for safety reasons. I always file IFR and find that if I'm at 12m or higher center doesn't hand me off to the approach controls that I pass over which greatly reduces my workload. So, here goes. At 15,000 after climbing out at gross weight: 2,200/28", 13 gph, 175 knots true. 2,200/30" 15 gph, 180 true maybe a little more. 2400/30" 17 gmp 190 true maybe a little less. Leaning to peak TIT at 2400/30 will reduce gph to 15. You will lose about 2-3 knots. If I have to stay "down low" 10,000' for headwinds, I will use 2400/30" and get 180 true. I am doing this from memory and if I checked my flight log might make some minor corrections, but that is close. To get the higher speeds, you will have to run your engine at 85% plus settings. The time savings are minimal. By the way, my CHT's rarely reach 360. Anything else? JG Quote
shallowskiff Posted October 10, 2011 Author Report Posted October 10, 2011 Quote: johnggreen Shallowskiff, I have flown my Bravo for almost seven years now. I'm based in MS and my profile is that I rarely fly less than 500 NM each time I crank the engine. My children are all in NC, VA, DC area. One went to Northwestern, so Chicago used to be a regular trip as well. Factor in a couple of business trips to the likes of CO and/or FL each year and well, you know why I have the Bravo. 90% of the time it is my wife and me with weekend bags. With TKS full, we are at gross. Sometimes I have to download a little fuel so I have pretty much perfected the max range speed/range/power combo for my airplane and make a note of almost every flight in my airplane flight log which stays in the airplane. By the way; even with TKS, my Bravo cruises about 4-7 knots over book speeds at gross! Yea, I'm a lucky man. ANYWAY: You asked a legitimate question and I do have the answers to a limit. The limit being is that I do not use high power settings. The TIO-540 AF1B is one of the lower horsepower TIO-540 varients so most of the cruise power settings given by the POH are well above 75%. All those figures are in your Lycoming owners manual and make for very interesting reading. To give you a feeling for power percentages, depending on altiude and temperature, according to the LOM (Lyc owner's manual) 75% can come at as little as 2200 rpm and 30" of manifold pressure. 2400/30" puts out about 220 h.p. wich would be about 80%. These figures will also vary according to whether you use best power (1650) or peak TIT. I use best power 90% of the time. As to where I fly. I try to fly from 13m to 17m. Never higher for safety reasons. I always file IFR and find that if I'm at 12m or higher center doesn't hand me off to the approach controls that I pass over which greatly reduces my workload. So, here goes. At 15,000 after climbing out at gross weight: 2,200/28", 13 gph, 175 knots true. 2,200/30" 15 gph, 180 true maybe a little more. 2400/30" 17 gmp 190 true maybe a little less. Leaning to peak TIT at 2400/30 will reduce gph to 15. You will lose about 2-3 knots. If I have to stay "down low" 10,000' for headwinds, I will use 2400/30" and get 180 true. I am doing this from memory and if I checked my flight log might make some minor corrections, but that is close. To get the higher speeds, you will have to run your engine at 85% plus settings. The time savings are minimal. By the way, my CHT's rarely reach 360. Anything else? JG Quote
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.