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Model Forum / Radio Controlled / Helicopters / June 2004RC Helicopter Hover Question
I have a GMP Cobra from 1985 that I had purchased back then. I had moved an had the helicopter crated for 8 years. I have recently uncrated it and was going over the manufacture's settings again. The manufacturer states that the helicopter will hover at 1500 rpm which should be at 1/2 stick and accelerate to 1650 rpm at full stick. I had used a tach and found that the idle rpm is about 1600 rpm and the maximum tends to exceed 2800 rpm. I have an OS Max 50 H engine that according to the manufacturer literature is good for 2000 - 16000 rpm. The question is why is the engine rpm much different than the hover rpm, and can the engine operate safetly at a higher rpm. If I increase pitch to slow the helicopter down then it should lift off sooner. Presently my maximum pitch is at 8 degrees positive. Any suggestions. Please reply to the newsgroup as the email address sending this message is an anti-spam address Dave Have you tried it with the blades on? 2800rpm +8 pitch wow!! > I have a GMP Cobra from 1985 that I had purchased back then. I had > moved an had the helicopter crated for 8 years. I have recently [quoted text clipped - 12 lines] > > Dave I had hoped that this was a serious newsgroup for helping those seeking information. I did not expect that escaped circus clowns were responding. Who would have thought that a helicopter needed main rotor blades to fly. I will go elsewhere for help. Dave >Have you tried it with the blades on? 2800rpm +8 pitch > [quoted text clipped - 21 lines] > > Gee Lighten up a bit 2800 rpm with a pitch of +8 as you suggested and any helicopter should be in orbit that's all he was suggesting and its is a serious newsgroup but we have a sense of humour Kevin I had hoped that this was a serious newsgroup for helping those seeking information. I did not expect that escaped circus clowns were responding. Who would have thought that a helicopter needed main rotor blades to fly. I will go elsewhere for help. Dave Stickman wrote: Have you tried it with the blades on? 2800rpm +8 pitch wow!! <12345@xray.net> wrote in message news:10drpi92b33va89@corp.supernews.com... I have a GMP Cobra from 1985 that I had purchased back then. I had moved an had the helicopter crated for 8 years. I have recently uncrated it and was going over the manufacture's settings again. The manufacturer states that the helicopter will hover at 1500 rpm which should be at 1/2 stick and accelerate to 1650 rpm at full stick. I had used a tach and found that the idle rpm is about 1600 rpm and the maximum tends to exceed 2800 rpm. I have an OS Max 50 H engine that according to the manufacturer literature is good for 2000 - 16000 rpm. The question is why is the engine rpm much different than the hover rpm, and can the engine operate safetly at a higher rpm. If I increase pitch to slow the helicopter down then it should lift off sooner. Presently my maximum pitch is at 8 degrees positive. Any suggestions. Please reply to the newsgroup as the email address sending this message is an anti-spam address Dave Woooo..............somebody's tired!  SignatureAlan alandotrait@btopenworlddot.com Remove the dots to reply http://heliweb.users.btopenworld.com/ Gee Lighten up a bit 2800 rpm with a pitch of +8 as you suggested and any helicopter should be in orbit that's all he was suggesting and its is a serious newsgroup but we have a sense of humour Kevin <12345@xray.net> wrote in message news:10dto99o90o6sff@corp.supernews.com... I had hoped that this was a serious newsgroup for helping those seeking information. I did not expect that escaped circus clowns were responding. Who would have thought that a helicopter needed main rotor blades to fly. I will go elsewhere for help. Dave Stickman wrote: Have you tried it with the blades on? 2800rpm +8 pitch wow!! <12345@xray.net> wrote in message news:10drpi92b33va89@corp.supernews.com... I have a GMP Cobra from 1985 that I had purchased back then. I had moved an had the helicopter crated for 8 years. I have recently uncrated it and was going over the manufacture's settings again. The manufacturer states that the helicopter will hover at 1500 rpm which should be at 1/2 stick and accelerate to 1650 rpm at full stick. I had used a tach and found that the idle rpm is about 1600 rpm and the maximum tends to exceed 2800 rpm. I have an OS Max 50 H engine that according to the manufacturer literature is good for 2000 - 16000 rpm. The question is why is the engine rpm much different than the hover rpm, and can the engine operate safetly at a higher rpm. If I increase pitch to slow the helicopter down then it should lift off sooner. Presently my maximum pitch is at 8 degrees positive. Any suggestions. Please reply to the newsgroup as the email address sending this message is an anti-spam address Dave Yep - How did you measure the RPM? The Gear ratio used at the time was 8.6:1 (yes - I had one) 2800 on the head would mean that the engine was doing 24080, not bad for an engine rated at 2000 - 16000 rpm, 16000 at 8.6:1 gives a head speed of 1860 The instructions said a hover around 1500 which would mean an engine speed of about 12900 which would be about half throttle. Now following that serious answer I am off to stick my funny red nose on and paint my face, gee has any one tried walking in these two foot long shoes. Gee Lighten up a bit 2800 rpm with a pitch of +8 as you suggested and any helicopter should be in orbit that's all he was suggesting and its is a serious newsgroup but we have a sense of humour Kevin <12345@xray.net> wrote in message news:10dto99o90o6sff@corp.supernews.com... I had hoped that this was a serious newsgroup for helping those seeking information. I did not expect that escaped circus clowns were responding. Who would have thought that a helicopter needed main rotor blades to fly. I will go elsewhere for help. Dave Stickman wrote: Have you tried it with the blades on? 2800rpm +8 pitch wow!! <12345@xray.net> wrote in message news:10drpi92b33va89@corp.supernews.com... I have a GMP Cobra from 1985 that I had purchased back then. I had moved an had the helicopter crated for 8 years. I have recently uncrated it and was going over the manufacture's settings again. The manufacturer states that the helicopter will hover at 1500 rpm which should be at 1/2 stick and accelerate to 1650 rpm at full stick. I had used a tach and found that the idle rpm is about 1600 rpm and the maximum tends to exceed 2800 rpm. I have an OS Max 50 H engine that according to the manufacturer literature is good for 2000 - 16000 rpm. The question is why is the engine rpm much different than the hover rpm, and can the engine operate safetly at a higher rpm. If I increase pitch to slow the helicopter down then it should lift off sooner. Presently my maximum pitch is at 8 degrees positive. Any suggestions. Please reply to the newsgroup as the email address sending this message is an anti-spam address Dave > I have a GMP Cobra from 1985 that I had purchased back then. I had > moved an had the helicopter crated for 8 years. I have recently [quoted text clipped - 10 lines] > Please reply to the newsgroup as the email address sending this message > is an anti-spam address Dave, set your blade pitch to give a progression from -1 at the closed thorttle positon, to +5 or 6 at the half throttle stick position and +9 at the full throttle position. Set your throttle BARREL movement so that it's closed with the throttle stick AND trim lever all the way "off", roughly 50-60% open at half stick position and obvipusly 100% open at the full throttle stick position. This should give you a fairly constant rotor speed while you're flying, no matter what the throttle stick position is. That'll at least get you up in th' air. SignatureBeav Please note my E-mail address is "beavis dot original at ntlworld dot com" (with the obvious changes) Beavisland now lives at www.beavisoriginal.co.uk Thanks Beav for the information. I will try your suggestions and let you know what happens Dave > > [quoted text clipped - 27 lines] > > > Thanks Beav for the information. I will try your suggestions and let > you know what happens Bear in mind Dave that the Cobra hasn't been in production for some time and parts are a "bit" rare (rare as rocking horse sh.t to be honest:-) so if you're a new newbie, fit some training sticks to the undercarriage to help stop the heli tipping. You don't say what type of radio you're using, but if you did, even more (probably uselss, but wtf:-) information would be forthcoming. SignatureBeav Please note my E-mail address is "beavis dot original at ntlworld dot com" (with the obvious changes) Beavisland now lives at www.beavisoriginal.co.uk |
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